Details of a Researcher - INAMI, Takayuki

Papers - INAMI, Takayuki

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Comparison of intra-session reliability of force-velocity-power variables between a horizontal dynamic leg press device and vertical jump tests

Nishioka T., Yamaguchi S., Hajima D., Kunita Y., Inami T.

Plos One 20 ( 9 September ) 2025.09

This study aimed to compare the intra-session reliability of force-velocity-power variables obtained from a horizontal dynamic leg press device (HDLPD) and vertical jump tests. Nineteen male field hockey players performed maximal leg extension movements in HDLPD under a wide range of available load conditions (100, 120, 140, 160, 180, and 200% body weight [BW]), followed by squat jumps (SJ) and countermovement jumps (CMJ) under unloaded (0kg), moderate- (22.0±4.6kg), and high-loaded (43.9±9.2kg) conditions. The peak and mean values of force, velocity, and power derived from the HDLPD, SJ, and CMJ were calculated. The HDLPD showed acceptable intrasession reliability for all experimental outcomes (intraclass correlation coefficient [ICC] = 0.845 to 0.974, coefficient of variation [CV] = 0.43% to 4.52%). The outcome variables during SJ and CMJ had acceptable intra-session reliability, except for the relative reliability of some variables (ICC=0.588–0.973, CV=1.19%–8.38%). The results of this study showed that the HDLPD has high intrasession reliability in measuring force-velocity-power variables for maximal leg extension performance. In addition, for some force-velocity-power variables, HDLPD can provide more reliable measurements than vertical jumps. Therefore, the HDLPD can be useful for practitioners who want to reliably measure leg extension strength, speed, and power outcomes.

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The Effects of Creatine Monohydrate Supplementation on Recovery from Eccentric Exercise-Induced Muscle Damage: A Double-Blind, Randomized, Placebo-Controlled Trial Considering Sex and Age Differences

Yamaguchi S., Inami T., Nishioka T., Morito A., Ishiyama K., Murayama M.

Nutrients 17 ( 11 ) 2025.06

Background/Objectives: In this study, we aimed to examine the effect of creatine monohydrate (CrM) supplementation on recovery from eccentric exercise-induced muscle damage (EIMD) in diverse populations, including different sexes and age groups. EIMD decreases maximal voluntary contraction (MVC), restricts the range of motion (ROM), and increases muscle stiffness and delayed-onset muscle soreness, all of which negatively impact athletic performance. Therefore, developing effective recovery strategies is essential. Methods: A double-blind, randomized, placebo-controlled trial was conducted with 40 healthy male and female participants. After 33 days of supplementation with either CrM or placebo (crystalline cellulose), the participants performed eccentric exercises. Recovery indices, including MVC, muscle stiffness, subjective muscle extensive soreness, fatigue, and upper arm circumference, were measured at baseline, immediately after exercise, 48 h post-exercise, and 96 h post-exercise. Results: The creatine supplementation group (CRE) demonstrated a significantly quicker recovery of MVC than the placebo group (PLA). Furthermore, reductions in shear modulus and muscle fatigue were observed in the CRE group. Notably, females in the CRE group exhibited a significant suppression of post-exercise edema, suggesting a sex-specific response. Conclusions: These findings indicate that CrM supplementation may enhance recovery from EIMD, contributing to the maintenance of muscle function and the reduction of discomfort after exercise. CrM has the potential to serve as a practical nutritional strategy to promote recovery, not only for athletes, but also for a broader population.

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Flight-Time Method Modified: Development of a Novel and More Accurate Method for Measuring Vertical Jump Height Using a Smartphone Application

Nishioka T., Yamaguchi S., Inami T.

International Journal of Sports Physiology and Performance 20 ( 1 ) 56 - 64 2025.01

ISSN 15550265

Purpose: The flight-time method (FT) is used for measuring vertical jump height (JH) in the field because of its convenience; however, FT overestimates JH when the lower limb is flexed at landing. Herein, we proposed a new method (ie, flight-time method modified [FTM]) to address the problem of FT and evaluate its validity and reliability. Methods: A total of 24 men performed 6 countermovement jumps on force plates (sampling rate: 1000 Hz) while being recorded with a smartphone high-speed camera at 240 frames·s–1. JH was calculated by the impulse–momentum method (IM), FT, and FTM. For FTM, the flight time and JH were calculated based on the displacement of the greater-trochanter marker using a smartphone application. Results: JH calculated using FT was significantly higher (P < .001) compared with JH calculated by IM; however, JH calculated by FTM showed no significant difference with JH calculated by IM. Furthermore, JH calculated by FTM, compared with JH calculated by FT (ρ = .882; 95% CI, .838–.914), exhibited a stronger, nearly perfect, and significantly positive correlation (ρ = .987; 95% CI, .982–.991) with JH calculated by IM and showed high reliability. Conclusions: The FTM proposed in this study had higher concurrent validity compared with FT and a high reliability for measuring countermovement JH because it was not affected by lower-extremity flexion at landing. Therefore, practitioners should consider using FTM as a convenient, low-cost, reliable, and more valid method for measuring JH in the field.

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Bioimpedance analysis for identifying new indicators of exercise-induced muscle damage

Yamaguchi S., Inami T., Ishida H., Nagata N., Murayama M., Morito A., Yamada S., Kohtake N.

Scientific Reports 14 ( 1 ) 2024.12

A noninvasive, immediate, and convenient method for assessing muscle tissue status during exercise-induced muscle damage (EIMD) has not been established. This study was designed to assess and determine parameters suitable for measuring EIMD after eccentric exercise, using multi-frequency bioimpedance analysis (BIA). Thirty-five young male participants performed dumbbell exercises with their left arm, and their BIA parameters were measured at various time points up to 168 h post exercise using a multi-frequency BIA device. At all-time points, intra and extracellular water content was greater in the left arm than in the right arm, whereas the impedance, reactance, resistance, and phase angle were lower in the left arm than in the right arm. Established EIMD indices, such as maximal isometric voluntary contraction, were measured and used in correlational analyses. Only reactance was correlated with biomarkers, indicating muscle damage (r = − 0.56 to − 0.49). Furthermore, reactance was found to correlate well with indirect indicators of EIMD, suggesting that it may be a suitable marker for evaluating EIMD. However, the relationship with the limited evaluation indices employed in this study is constrained. Future studies should investigate the correlation between reactance and direct damage indicators, such as structural damage, observed in biopsies.

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Relationship between changes in muscle stiffness after a comfortable massage and the massage pressure

Inami T., Yamaguchi S., Kim H.K., Miyagawa H., Murayama M.

Journal of Bodywork and Movement Therapies (Journal of Bodywork and Movement Therapies) 39 350 - 355 2024.07

ISSN 13608592

Introduction: This study aimed to determine whether massage pressure on the target muscles (biceps brachii muscle [BB] and the medial head of the gastrocnemius muscle [MG]) is related to the massage effect (reducing muscle stiffness). Method: Nine healthy participants participated in this study. A physiotherapist massaged the upper arms and lower legs of participants on a rigid desk in a laboratory. Massage was delivered for 10 min with a 3-min rest. The shear modulus (i.e., the muscle stiffness), assessed by shear wave elastography, was measured at various time points (before [PRE], immediately after [POST], and 5 [POST-5], 10, 15, and 20 min after the massage). The massage pressure data (N) were obtained only during massage by force plate sensors. Results: The BB shear modulus was significantly reduced POST massage. The MG shear modulus significantly reduced POST massage and remained clearly reduced until POST-5. There was a negative correlation between the total massage pressure and the % change in the shear modulus in both muscles. Discussion: Since the spindle (BB) and pennate (MG) muscles have structural differences, our results suggest that these differences may affect the pattern of changes in the shear modulus in response to massage. Conclusion: Massage pressure is related to the massage effect (reducing muscle stiffness), and its relationships to POST are not related to the differences in the morphologies of the spindle (BB) and pennate muscles (MG). However, differences in the morphologies of the spindle and pennate muscles may cause differences in the duration of the massage effects.

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Effects of Different Target Distances on the Kinematics of Hip, Knee, and Ankle Joints in the Fencing Lunge

Chida K., Inami T., Yamaguchi S., Yoshida Y., Kohtake N.

Biomechanics (Switzerland) (Biomechanics (Switzerland)) 4 ( 2 ) 309 - 318 2024.06

This study aimed to evaluate the effects of different target distances on various leg joints in the fencing lunge (lunge). Fifteen fencers performed the lunges from three different target distances (normal, short, and long). Joint angle data in the sagittal plane of the hip, knee, and ankle of the front and rear legs were measured using a 3D motion analysis system (Miqus M3). Joint angle variables were compared between each distance using a one-way repeated-measures analysis of variance and Friedman tests (p < 0.05). The results showed significant differences in various extensions, ranges of motion, and flexion angles in the measured joints for all distances. As the distances increased, there was greater flexion of the rear knee joint early during the lunge, followed by greater extension of the rear hip and knee joints, greater plantar flexion of the rear ankle joint, and higher peak velocity of the body center of mass. Furthermore, target distance extension was suggested to significantly affect front hip and knee joint flexion during the braking phase of the lunge. This study provides insight and information valuable to coaches and fencers operating in actual competition settings.

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The Effect of Prior Creatine Intake for 28 Days on Accelerated Recovery from Exercise-Induced Muscle Damage: A Double-Blind, Randomized, Placebo-Controlled Trial

Yamaguchi S., Inami T., Ishida H., Morito A., Yamada S., Nagata N., Murayama M.

Nutrients (Nutrients) 16 ( 6 ) 2024.03

Despite the known beneficial effects of creatine in treating exercise-induced muscle damage (EIMD), its effectiveness remains unclear. This study investigates the recovery effect of creatine monohydrate (CrM) on EIMD. Twenty healthy men (21–36 years) were subjected to stratified, randomized, double-blind assignments. The creatine (CRE) and placebo (PLA) groups ingested creatine and crystalline cellulose, respectively, for 28 days. They subsequently performed dumbbell exercises while emphasizing eccentric contraction of the elbow flexors. The EIMD was evaluated before and after exercise. The range of motion was significantly higher in the CRE group than in the PLA group 24 h (h) post exercise. A similar difference was detected in maximum voluntary contraction at 0, 48, 96, and 168 h post exercise (p = 0.017–0.047). The upper arm circumference was significantly lower in the CRE group than in the PLA group at 48, 72, 96, and 168 h post exercise (p = 0.002–0.030). Similar variation was observed in the shear modulus of the biceps brachii muscle at 96 and 168 h post exercise (p = 0.003–0.021) and in muscle fatigue at 0 and 168 h post exercise (p = 0.012–0.032). These findings demonstrate CrM-mediated accelerated recovery from EIMD, suggesting that CrM is an effective supplement for EIMD recovery.

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Assessing the validity of two-dimensional video analysis for measuring lower limb joint angles during fencing lunge

Chida K., Inami T., Yamaguchi S., Nishioka T., Yoshida Y., Kohtake N.

Frontiers in Sports and Active Living (Frontiers in Sports and Active Living) 6 2024

Introduction: The fencing lunge (lunge), characterized by minimal body rotation, offers a movement well-suited for 2D video analysis. However, to the best of our knowledge, the validity of 2D video analysis for fencing has not been verified. This study aimed to validate 2D video analysis by comparing lower limb joints (hip, knee, and ankle joints) angles during lunge using both 2D video analysis and 3D motion analysis methods. Methods: Twenty-two male fencers performed lunge trials that were simultaneously recorded using eight motion capture cameras (Qualisys Miqus M1) and two digital video cameras (Sony AX-450 and AX450a). Results: The 2D video analysis results exhibited an extremely large correlation in knee joint angles of the front and rear legs in the sagittal with those from 3D motion analysis (r = 0.93–0.99). However, while a robust correlation was found between the ankle joint angles of the front and rear legs (r = 0.82–0.84), a large bias was also observed (−5.23° to −21.31°). Conversely, for the hip joints of the rear leg, a moderate correlation (r = 0.31) and a large bias (−10.89°) were identified. Conclusions: The results of this study will contribute to the development of coaching using 2D video analysis in competition settings because such analysis can be a useful alternative to 3D motion analysis when measuring the knee joint angle of the front leg and rear leg in the sagittal plane. However, for the ankle joint angle, further research on the optimal shooting position and height of the digital video camera is needed, whereas for the hip joint angle, 3D motion analysis is recommended at this time.

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Effects of lunges inserted in walking (eccentric walking) on lower limb muscle strength, physical and cognitive function of regular walkers

Katsura Y., Takeda N., Inami T., Yamaguchi S., Takahashi S., Nakamura M., Nosaka K.

European Journal of Applied Physiology (European Journal of Applied Physiology) 124 ( 8 ) 2343 - 2352 2024

ISSN 14396319

Introduction: Walking is a popular exercise but does not increase lower limb muscle strength and balance. We hypothesized that muscle strength, physical and cognitive function would be improved by inserting lunges in conventional walking. Methods: Eleven regular walkers (54–88 years) who had more than 5000 steps in exercise walking a day at least 5 days a week participated in this study. They walked as usual for the first 4 weeks and included lunges and descending stairs or slope walking (i.e., eccentric walking) for the next 8 weeks. The steps of eccentric walking were gradually increased from 100 to 1000 steps per week over 8 weeks. Results: The average steps per day were 10,535 ± 3516 in the first 4 weeks, and 10,118 ± 3199 in the eccentric walking period without a significant difference. No significant changes in maximal voluntary isometric contraction torque of the knee extensors (MVC), 30-s chair stand (CS), 2-min step, balance assessed by center of pressure movement area with eyes close, sit and reach, a digit symbol substitution test (DSST) for cognitive function were observed in the first 4 weeks. However, significant (P < 0.05) improvements were evident in MVC (18.6 ± 15.7%), CS (24.2 ± 17.3%), balance (– 45.3 ± 34.5%), and DSST (20.8 ± 16.7%) from weeks 4 to 12. Serum complement component 1q concentration decreased (P < 0.05) from weeks 4 to 12, although no changes in serum glucose, triglyceride, and cholesterol concentrations were observed. Conclusion: These results supported the hypothesis, and suggest that eccentric walking provides effects that are not achieved by conventional walking.

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Relationships between Changes in Muscle Shear Modulus, Urinary Titin N- Terminal Fragment, and Maximum Voluntary Contraction Torque after Eccentric Exercise of the Elbow Flexors

Inami T., Yamaguchi S., Nishioka T., Ishida H., Morito A., Yamada S., Nagata N., Murayama M.

Journal of sports science & medicine (Journal of sports science & medicine) 22 ( 4 ) 797 - 805 2023.12

The study aimed to investigate the relationships between the shear modulus of the biceps brachii (BB) and brachialis muscle (BA) and the total of the two (BB+BA), and urinary titin N-terminal fragment (UTF), maximum voluntary isometric contraction (MVC), and other indirect markers. Fifteen healthy men performed five sets of 10 eccentric contractions using a dumbbell corresponding to 50% of MVC at 90° measured at baseline. The elbow joint of the left arm was extended from 90° to 180° (180° = full extension) in 5 s in the exercise, and was returned with support from the examiner to prevent concentric contraction. Shear modulus of BB and BA were measured by ultrasound shear wave elastography, and UTF, MVC, and range of motion of the elbow joint (ROM) were recorded before; immediately after; and 1, 24, 48, 72, 96, and 168 h after the exercise. After calculating the shear modulus of BB and BA, two values were added (BB+BA). The shear modulus peaked at 48 h, UTF peaked at 96 h, MVC and ROM changed largest at immediately, and muscle soreness peaked at 48 h post-exercise. Significant (p < 0.05) relationships were found between changes in BB shear modulus and BA shear modulus (r = 0.874), BB+BA shear modulus (r = 0.977), UTF (r = 0.681), and MVC (r = -0.538). Significant (p < 0.05) relationships were also observed between changes in BA shear modulus and BB+BA shear modulus (r = 0.957), UTF (r = 0.682), MVC (r = -0.522), and ROM (r = -0.600). Moreover, significant (p < 0.05) relationships were observed between changes in BB+BA shear modulus and UTF (r = 0.703), MVC (r = -0.549), and ROM (r = -0.547). These results indicate that shear modulus of each muscle (i.e., BB and BA) provide more precise information about muscle damage than UTF, MVC and ROM.

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The Effect of Contrast Water Therapy on Dehydration during Endurance Training Camps in Moderate-Altitude Environments

Inami T., Yamaguchi S., Nishioka T., Chida K., Hoshina K., Ito O., Hashimoto T., Murayama M.

Sports (Sports) 11 ( 12 ) 2023.12

The effects of contrast water therapy (CWT) on dehydration at moderate altitudes during training camps remain unknown. We hypothesized that CWT reduces dehydration resulting from training at moderate altitudes and improves performance, akin to conditions at sea level. A 13-day endurance training camp was held at a moderate altitude of 1100 m and included 22 university athletes, who were divided into two groups (CWT group, n = 12; control (CON) group, n = 10). The sample size was calculated based on an α level of 0.05, power (1 β) of 0.8, and effect size of 0.25 based on two-way ANOVA. Longitudinal changes over 13 days were compared using a two-group comparison model. Additionally, 16 athletes participated in an additional performance verification analysis. Subjective fatigue, body mass, and water content (total body water (TBW), extracellular water (ECW), and intracellular water) were measured using bioimpedance analysis every morning, and the titin N-terminal fragment in urine (UTF) was measured as an index of muscle damage. For performance verification, 10 consecutive jump performances (with the reactive strength index (RSI) as an indicator) were evaluated as neuromuscular function indices. The results indicated that the UTF did not significantly differ between the two groups. Moreover, the ECW/TBW values, indicative of dehydration, on days 4 and 5 in the CWT group were significantly lower than those in the CON group. However, there was no significant difference in RSI between the two groups. Therefore, although CWT reduces dehydration in the early stages of the training camp, it may not affect performance.

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Relationship between Body Center of Mass Velocity and Lower Limb Joint Angles during Advance Lunge in Skilled Male University Fencers

Chida K., Inami T., Yamaguchi S., Yoshida Y., Kohtake N.

Biomechanics (Switzerland) (Biomechanics (Switzerland)) 3 ( 3 ) 377 - 388 2023.09

We investigated the influence of advance lunging in fencing from the perspective of velocity and lower limb joint angles to identify how the joint angles contribute to the peak velocity in a lunge with advance (LWA). Fourteen skilled athletes (age: 19.6 ± 0.9 years, height: 171.2 cm ± 5.2 cm, weight: 63.7 kg ± 5.3 kg, and fencing experience: 9.7 ± 3.1 years) participated by performing two types of attacking movements, and data were collected with a 3D movement analysis system. A correlation between the peak velocity of the body center of mass (CoM) in an advance lunge and several joint angle variables (rear hip peak flexion angle (r = 0.63), rear ankle peak dorsiflexion angle (r = −0.66), rear ankle range of motion (r = −0.59), and front hip peak extension angle (r = 0.54)) was revealed. In addition, the joint angle variables that significantly predicted peak CoM velocity during an LWA were the rear knee peak flexion angle (β = 0.542), rear knee peak extension angle (β = −0.537), and front knee peak extension angle (β = −0.460). Our findings suggest that the rear leg hip joint, rear leg ankle joint, and front leg hip joint may control the acceleration generated by an LWA. Furthermore, more flexion of the rear leg knee joint in the early phase of the lunge and greater extension of the rear and front leg knee joints at the end of the lunge phase may help increase peak velocity.

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Chrono-exercise: Time-of-day-dependent physiological responses to exercise

Kim H.K., Radak Z., Takahashi M., Inami T., Shibata S.

Sports Medicine and Health Science (Sports Medicine and Health Science) 5 ( 1 ) 50 - 58 2023.03

Exercise is an effective strategy to prevent and improve obesity and related metabolic diseases. Exercise increases the metabolic demand in the body. Although many of the metabolic health benefits of exercise depend on skeletal muscle adaptations, exercise exerts many of its metabolic effects through the liver, adipose tissue, and pancreas. Therefore, exercise is the physiological state in which inter-organ signaling is most important. By contrast, circadian rhythms in mammals are associated with the regulation of several physiological and biological functions, including body temperature, sleep-wake cycle, physical activity, hormone secretion, and metabolism, which are controlled by clock genes. Glucose and lipid tolerance reportedly exhibit diurnal variations, being lower in the evening than in the morning. Therefore, the effects of exercise on substrate metabolism at different times of the day may differ. In this review, the importance of exercise timing considerations will be outlined, incorporating a chrono-exercise perspective.

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Damage and recovery of the intrinsic and extrinsic foot muscles from running a full marathon

Fukano M., Nakagawa K., Higashihara A., Inami T., Narita T.

Scandinavian Journal of Medicine and Science in Sports (Scandinavian Journal of Medicine and Science in Sports) 33 ( 8 ) 1486 - 1493 2023

ISSN 09057188

Purpose: To investigate the effects of full marathon running on intrinsic and extrinsic foot muscle damage and to determine the relationship with the height change of the longitudinal foot arch following full marathon completion. Methods: Magnetic resonance imaging-measured transverse relaxation time (T2) of the abductor hallucis (ABH), flexor digitorum brevis (FDB) and quadratus plantae (QP), flexor digitorum longus (FDL), tibialis posterior (TP), and flexor hallucis longus (FHL) from 22 collegiate runners were assessed before and 1, 3, and 8 days after full marathon running. The three-dimensional foot posture of 10 of the 22 runners was further obtained using a foot scanner system before and 1, 3, and 8 days after the marathon. Results: Marathon-induced increases in T2 were observed in the QP, FDL, TP, and FHL 1 day after the marathon (+7.5%, +4.7%, +6.7%, and +5.9%, respectively), with the increased T2 of TP persisting until 3 days after the marathon (+4.6%). T2 changes of FDL and FHL from pre-marathon to DAY 1 showed direct correlations with the corresponding change in the arch height ratio (r = 0.823, p = 0.003, and r = 0.658, p = 0.038). Conclusion: The damage and recovery response from a full marathon differed among muscles; QP, FDL, TP, and FHL increased T2 after the marathon, whereas ABH and FDB did not. In addition, T2 changes in FDL and FHL and the arch height ratio change were correlated. Our results suggest that the extrinsic foot muscles could be more susceptible to damage than the intrinsic during marathon running.

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The Validity and Reliability of a Smartphone Application for BreakPoint Angle Measurement during Nordic Hamstring Exercise

Soga T., Yamaguchi S., Inami T., Saito H., Hakariya N., Nakaichi N., Shinohara S., Akiyama K., Hirose N.

International Journal of Sports Physical Therapy (International Journal of Sports Physical Therapy) 18 ( 4 ) 917 - 922 2023

Background A recently developed smartphone application (Nordic Angle) allows the automatic calculation of the break-point angle (BPA) during Nordic hamstring exercise (NHE) without transferring the collected data to a computer. The BPA is the point at which the hamstrings are unable to withstand force. However, the validity of the BPA values obtained by this method has not been examined. Hypothesis/Purpose This study aimed to evaluate the validity and reliability of the Nordic Angle by comparing the BPA values of the Nordic Angle with those of two-dimensional motion analysis software that can calculate the angles and angular velocities of various joints. Study Design Cohort assessing Validity and Reliability Methods The validity of the Nordic Angle BPA data was verified by Spearman’s correlation test for consistency with the movement analysis data, and the magnitude of the correlation was indicated by rs. The agreement between these measurements was examined using the Bland-Altman analysis. The reliability of the Nordic Angle and motion analysis was examined using the intraclass correlation coefficient (ICC) (1,k) based on data from repeated trials within a day. Results Although the spearman correlation between the Nordic angle and the angle determined using motion analysis did not reach statistical significance (p = 0.052), a very large correlation was present (rs = 0.75). The difference between the mean values of the Nordic Angle and motion analysis was 0.4 ± 2.1°, and the limits of agreement ranged from-3.9° to 4.6°. In two BPA measurements, the Nordic Angle showed perfect reliability (ICC = 1.00, p < 0.001), while motion analysis showed nearly perfect reliability (ICC = 0.97, p < 0.001). Conclusion The Nordic Angle, which has both validity and reliability, may be appropriate for field measurement because it allows immediate feedback of BPA and the measurement of many athletes.

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Hamstring Activity Before and After Break-Point Angle Calculated By Smartphone Application During the Nordic Hamstring Exercise

Soga T., Yamaguchi S., Inami T., Saito H., Hakariya N., Nakaichi N., Shinohara S., Sasabe K., Nakamura H., Laddawong T., Akiyama K., Hirose N.

International Journal of Sports Physical Therapy (International Journal of Sports Physical Therapy) 18 ( 6 ) 1290 - 1298 2023

INTRODUCTION Previous studies have reported a gradual decrease in biceps femoris (BF) electromyography (EMG) activity after the break-point angle (BPA) during the Nordic hamstring exercise (NHE). However, no investigation has been conducted on BF EMG activity before and after BPA as calculated using a smartphone application (Nordic Angle app). HYPOTHESIS/PURPOSE The aim of this study was to investigate the BF EMG activity before and after BPA, as calculated using the Nordic Angle app. The hypotheses were that BF EMG activity would peak near the BPA and gradually diminish afterward. METHODS After a warm-up, participants performed three repetitions of prone leg curls to discern maximum voluntary isometric contraction (MVIC) of the hamstrings. The peak value of the BF EMG activity during the prone leg curl was used to convert BF EMG activity during NHE to %MVIC. BPA during NHE was calculated using the Nordic Angle app by analyzing a movie recorded with an iPhone camera. Additionally, the knee flexion angle during NHE was determined using two-dimensional motion analysis software based on video data. To compare EMG activity before and after BPA calculated by the Nordic Angle app, the knee flexion angle was divided into seven phases: 10-15° before BPA, 5-10° before BPA, BPA ± 5°, 5-10° after BPA, 10-15° after BPA, 15-20° after BPA, and 20-25° after BPA. RESULTS There was no significant difference between the BPA of the Nordic angle and the knee flexion angle at peak BF EMG activity (d = 0.13, p = 0.678). The BF EMG activity at 20-25° after BPA was significantly lower than the BF EMG activity at BPA ± 5° (d = 0.87, p = 0.011). CONCLUSIONS To prevent the recurrence of hamstring injuries, it is important to incorporate knee flexion exercises that enhance BF EMG activity at 15-35° of knee flexion (0° indicates a fully extended knee). Thus, it is recommended to keep the BPA of the Nordic Angle within 35° to effectively prevent recurrent hamstring injuries during NHE.

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Changes in biceps brachii muscle hardness assessed by a push-in meter and strain elastography after eccentric versus concentric contractions

Murayama M., Inami T., Shima N., Yoneda T., Nosaka K.

Scientific Reports (Scientific Reports) 12 ( 1 ) 2022.12

Changes in biceps brachii muscle hardness assessed by a push-in meter (PM) and strain elastography (SE) were compared between eccentric (ECC) and concentric contractions (CON) of the elbow flexors to test the hypothesis that muscle hardness would increase greater after ECC. Ten men performed 5 sets of 10 ECC with their non-dominant arms and 5 sets of 10 CON with their dominant arms using a dumbbell corresponding to 50% of maximum voluntary isometric contraction (MVIC) force at 90º elbow flexion. Before and 1–4 days after the exercise, MVIC force, elbow joint angles, upper-arm circumference, and muscle soreness as muscle damage makers, and biceps brachii muscle hardness at maximally extended elbow joint by PM and SE were measured. Changes in these measures over time were compared between ECC and CON. All muscle damage markers showed greater changes after ECC than CON (p < 0.001). Muscle hardness assessed by PM and SE increased (p < 0.05) and peaked at 4 days post-ECC with 154.4 ± 90.0% (PM) and 156.2 ± 64.2% (SE) increases from the baseline, but did not change significantly after CON. The changes in muscle hardness post-ECC were correlated between PM and SE (r = 0.752, p < 0.001). A correlation (p < 0.001) between the normalized changes in resting elbow joint angle and changes in muscle hardness assessed by PM (r = − 0.772) or SE (r = − 0.745) was also found. These results supported the hypothesis and suggest that the increases in muscle hardness after ECC were associated with muscle damage (increased muscle stiffness), and PM and SE detected muscle hardness changes similarly.

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Changes in Muscle Shear Modulus and Urinary Titin N-Terminal Fragment after Eccentric Exercise

Inami T., Yamaguchi S., Ishida H., Kohtake N., Morito A., Yamada S., Shimomasuda M., Haramoto M., Nagata N., Murayama M.

Journal of Sports Science and Medicine (Journal of Sports Science and Medicine) 21 ( 4 ) 536 - 544 2022.12

This study aimed to investigate the relationship between the muscle shear modulus of the biceps brachii, urinary titin N-terminal fragment (UTF), and other damage markers after eccentric exer-cise. Seventeen healthy males performed five sets of ten eccentric exercises with dumbbells weighing 50% of the maximum voluntary contraction (MVC) at the elbow joint. Muscle shear modulus with range of interest set to only biceps brachii muscle measured by ultrasound shear wave elastography, UTF, MVC, range of motion (ROM), and soreness (SOR) were recorded before, immedi-ately after, and 1, 24, 48, 72, 96, and 168 h after eccentric exer-cise. Each marker changed in a time course pattern, as found in previous studies. The peak shear modulus showed a moderate negative correlation with peak MVC (r = –0.531, P < 0.05) and a strong positive correlation with peak UTF (r = 0.707, P < 0.01). Our study results revealed a significant relationship between muscle strength, shear modulus measured by ultrasound SWE, and titin measured by UTF, as a non-invasive damage marker after eccentric exercise to track changes in EIMD.

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Ice slurry ingestion improves physical performance during high-intensity intermittent exercise in a hot environment

Morito A., Inami T., Hirata A., Yamada S., Shimomasuda M., Haramoto M., Kato K., Tahara S., Oguma Y., Ishida H., Kohtake N.

PLoS ONE (PLoS ONE) 17 ( 9 September ) 2022.09

Ice slurry ingestion enhances exercise performance by lowering the core body temperature. However, an operational issue related to this ingestion is the requirement for a high intake of 7.5 gkg-1 to produce the desired effects. We investigated the effects of the intake of low amounts of ice slurry at ?2?C on the tympanic temperature and exercise performance during repeated high-intensity intermittent exercises in a hot environment. This study was a randomized, crossover study, with a 6-day washout period. Twelve university rugby union players performed two 30-min sessions of high-intensity intermittent exercises separated by a 15-min half-Time break on a cycle ergometer in a hot environment (28.8?C 0.1?C, 49.5% 0.6% relative humidity). The participants ingested 450 g of ?2?C-ice slurry (ICE), or a 30?Cbeverage (CON) having the same composition as ICE, or 30?C-water (WAT) during the halftime break. The tympanic temperature and skin temperature were measured as the physiological data, and the peak power and mean power as the exercise performance data. The tympanic temperature at the half-Time break and beginning of the 2nd session was significantly lower in the ICE group as compared with the CON and WAT groups. The skin temperature at the half-Time break was significantly lower in the ICE group as compared with the WAT group. While the peak power and mean power during the 2nd session were significantly greater in the ICE group as compared with the CON and WAT groups. Our findings suggest that even the intake of lower amounts, as compared with those used in previous studies, of low-Temperature ice slurry can reduce the body temperature and improve the peak power. These results suggest that intake of low-Temperature ice slurry as a strategy for internal body cooling is useful for improving endurance exercise performance in hot environments.

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Late-afternoon endurance exercise is more effective than morning endurance exercise at improving 24-h glucose and blood lipid levels

Kim H.K., Furuhashi S., Takahashi M., Chijiki H., Nanba T., Inami T., Radak Z., Sakamoto S., Shibata S.

Frontiers in Endocrinology (Frontiers in Endocrinology) 13 2022.07

Background: Glucose and lipid tolerance reportedly exhibit diurnal variations, being lower in the evening than in the morning. Therefore, the effects of exercise on glucose and blood lipid levels at different times of the day may differ. This study aimed to investigate the effects of short-term endurance exercise intervention in the morning versus late afternoon on 24-h blood glucose variability and blood lipid levels. Methods: Twelve healthy young men participated in a randomized crossover trial. The participants were assigned to morning (09:00–11:00) or late afternoon (16:00–18:00) endurance exercise for a week, consisting of supervised exercise sessions on Mondays, Wednesdays, and Fridays. In the morning and evening trials, the participants walked for 60 min on a treadmill at approximately 60% of maximal oxygen uptake (VO2max). Following a 2-week wash-out period, the participants performed the exercise training regimen at another time point. Continuous glucose monitoring was used to evaluate blood glucose fluctuations during each 24-h trial period. Blood samples were collected before and after each intervention to examine blood lipid and hormonal responses. Results: Examination of the area under the curve (AUC) of the glucose level changes for 24 h after the late afternoon versus morning exercise intervention revealed significantly lower values for the former versus the latter (P < 0.01). The AUC of glucose level changes after each meal was also lower after the late afternoon versus morning intervention, and significantly lower values were observed in the late afternoon versus morning trial for breakfast and dinner (P < 0.05, P < 0.01). In addition, a significant decrease in triglycerides (TG) and TG/high-density lipoprotein cholesterol (HDL-C) was noted after versus before the late afternoon intervention (P < 0.05). Conclusions: These results suggest that late afternoon endurance exercise is more effective than morning endurance exercise at improving 24-h glucose and triglyceride levels.

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The acute mechanism of the self-massage-induced effects of using a foam roller

Yoshimura A., Sekine Y., Schleip R., Furusyo A., Yamazaki K., Inami T., Murayama M., Hirose N.

Journal of Bodywork and Movement Therapies (Journal of Bodywork and Movement Therapies) 27 103 - 112 2021.07

ISSN 13608592

Introduction: Maintaining flexibility, often defined as range of motion (ROM), is important. Recently, self-massage using a foam roller (FR) has been used in clinical and/or sports settings to effectively and immediately improve ROM. Many studies have found significant increases in ROM following the FR intervention; however, the mechanism of the effect is unclear. We aimed to clarify this mechanism regarding the ROM effects following the FR intervention by evaluating local tissue and autonomic nervous system responses. Method: The study employed a crossover design that included a comparison between non-intervention (CON trial: left leg) and intervention (FR trial: right leg) groups. Fourteen volunteers participated. Nine outcomes (passive maximum ankle ROM [ROM with a specified and non-specified passive strength], tissue hardness, skin temperature, water contents, circumference, blood flow velocity, pressure pain threshold, autonomic nervous system, and heart rate) were investigated before (PRE) and 0 min (POST0), 20 min (POST20), 40 min (POST40), and 60 min (POST60) post intervention. Results: Skin temperature, impedance, and circumference changed significantly following the intervention, and increased ROM with non-specified strength was observed. Discussion: Although we found that the FR intervention influenced skin temperature, impedance, circumference, and ROM, adaptability to the intervention may differ depending on an individual's characteristics. Females and/or individuals with a high body water content could obtain greater positive ROM effects than males and/or individuals with a low body water content. Conclusion: These findings suggest that the FR intervention may be an effective method to improve ROM, with alterations of skin temperature, impedance, and circumference.

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Greater knee varus angle and pelvic internal rotation after landing are predictive factors of a non-contact lateral ankle sprain

Mineta S., Inami T., Hoshiba T., Higashihara A., Kumai T., Torii S., Hirose N.

Physical Therapy in Sport (Physical Therapy in Sport) 50 59 - 64 2021.07

ISSN 1466853X

Objectives: This study aimed to clarify the kinematic, kinetic characteristics associated with lateral ankle sprain. Design: A 16-month prospective cohort study. Setting: Laboratory. Participants: A total of 179 college athletes. Main outcome measures: Joint kinematics, moment during single-leg landing tasks, and ankle laxity were measured. The attendance of each participating team, injury mechanism, existence of body contact, presence of orthosis, with or without medical diagnosis, and periods of absence were recorded. Results: Twenty-nine participants incurred lateral ankle sprain during non-contact motion. The Cox regression analysis revealed that greater knee varus peak angle (hazard ratio: 1.16 [95% confidence interval: 1.10–1.22], p < 0.001) and greater pelvic internal rotation peak angle toward the support leg were associated with lateral ankle sprain (hazard ratio: 1.08 [95% confidence interval: 1.02–1.15], p = 0.009). The cut-off values for each predictive factor were −0.17° (area under the curve = 0.89, p < 0.001) and 6.63° (area under the curve = 0.74, p < 0.001), respectively. Conclusions: A greater knee varus peak angle and pelvic internal rotation peak angle after single-leg landing are predictive factors for lateral ankle sprain.

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Body composition of collegiate kendo players.

Yoshida, Y., Inami, T., Takase, T.

Journal of Sports Medicine and Physical Fitness Accepted for publication 2021

Research paper (scientific journal), Joint Work, Accepted

Increase in foot arch asymmetry after full marathon completion

Fukano M., Nakagawa K., Inami T., Higashihara A., Iizuka S., Narita T., Maemichi T., yoshimura A., Yamaguchi S., Iso S.

Journal of Sports Sciences (Journal of Sports Sciences) 39 ( 21 ) 2468 - 2474 2021

ISSN 02640414

Long-distance running results in lowering of the foot medial longitudinal arch, but it is unknown whether the left and right arches decrease equally. This study aimed to determine whether foot arch asymmetry increases upon completion of a full marathon and to identify factors capable of explaining the degree of asymmetry of navicular height and navicular height displacement. The three-dimensional foot posture data of 74 collegiate runners were obtained using an optical foot scanner system before (PRE) and immediately after (POST) a full marathon. The navicular height and arch height ratio (normalised navicular height by foot length) of both feet significantly decreased from PRE to POST full marathon completion (44.3 ± 6.3 mm versus 40.8 ± 6.5 mm, 17.8 ± 2.5 versus 16.6 ± 2.7, respectively; p < 0.001, both). The asymmetry of the arch height ratio was significantly greater POST than PRE marathon. Multiple linear regression analysis indicated that the POST-race Asymmetry Index (AI) of navicular height was significantly predicted by the PRE-race AI of navicular height; navicular height displacement was predicted by PRE-race navicular height and the marathon time. Full marathon running induced increasing asymmetry and lowering of the medial longitudinal arch in runners.

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Changes in urinary titin N-terminal fragments as a biomarker of exercise-induced muscle damage in the repeated bout effect

Yamaguchi, S., Suzuki, K., Inami, T., Okada, J.

Journal of Science and Medicine in Sport (Elsevier) Accepted for publication ( 6 ) 536 - 540 2020

Research paper (scientific journal), Joint Work, Accepted, ISSN 14402440

© 2019 Sports Medicine Australia Objectives: Muscle damage symptoms induced by unaccustomed eccentric contraction exercise can be reduced by repeating the experience several times. This phenomenon is termed the repeated bout effect. Although traditional biochemical markers require invasive blood sampling, biochemical measurements have recently been developed that can be non-invasively performed using urinary titin N-terminal fragment (UTF). However, it is unclear whether UTF can reflect the repeated bout effect. Therefore, the aim of the present study was to clarify whether UTF decreased with the repeated bout effect. Design: This study compared changes in muscle damage markers between bouts of exercise performed for the first and second time. Methods: Eight young men performed 30 eccentric exercises of the elbow flexor on the first day of the first week (Bout 1). A second bout of eccentric exercises, same as the first, was performed 2 weeks later, (Bout 2). The dependent variables were muscle soreness (SOR), maximal voluntary isometric contraction (MVIC), range of motion (ROM), creatine kinase (CK), and UTF. All dependent variables were analyzed using two-way analysis of variance. Results: No significant difference was observed in workload or peak torque between the first and second exercise bouts. SOR as well as CK and UTF were significantly lower and ROM and MVIC were significantly higher in Bout 2 in comparison to Bout 1. Conclusions: These results suggest that UTF sensitively reflects the repeated bout effect and exercise-induced muscle damage can be non-invasively measured.

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Changes in urinary titan N-terminal fragment concentration after concentric and eccentric exercise

Yamaguchim S., Suzuki, K., Inami, T., Kanda, K., Hanye, Z., Okada, J.

Journal of Sports Science and Medicine 19 121 - 129 2020

Research paper (scientific journal), Joint Work, Accepted

Changes in urinary titin N-terminal fragment concentration after concentric and eccentric exercise

Yamaguchi S., Suzuki K., Inami T., Kanda K., Hanye Z., Okada J.

Journal of Sports Science and Medicine (Journal of Sports Science and Medicine) 19 ( 1 ) 121 - 129 2020

© Journal of Sports Science and Medicine (2020). We aimed to compare the urinary titin N-terminal fragment (UTF) concentration after concentric and eccentric exercise and to clarify the specific response of UTF to exercise-induced muscle damage (EIMD). Nine healthy young men performed 30 concentric elbow flexion exercises with maximum effort, rested for at least eight weeks, and performed eccentric exercises at the same workload using the same arm. Changes in the maximal voluntary isometric contraction (MVIC), muscle soreness (SOR), range of motion (ROM), serum creatine kinase (CK) activity, and UTF concentrations were recorded before and after for six consecutive days after exercise. There was no significant difference in workload during exercise between the two exercise types. However, serum CK activity increased after eccentric exercise (p < 0.05). Additionally, MVIC, SOR, ROM, and UTF concentration were significantly higher after eccentric exercise than after concentric exercise (p < 0.05). Although workload was the same, the UTF concentration greatly increased after eccentric exercise. Based on these results, we suggest that UTF can be a non-invasive and highly specific biomarker of EIMD.

Regional differences in hamstring muscle damage after a marathon

Higashihara A., Nakagawa K., Inami T., Fukano M., Iizuka S., Maemichi T., Hashizume S., Narita T., Hirose N.

PloS one (PloS one) 15 ( 6 ) 2020

Previous studies suggest that marathon running induces lower extremity muscle damage. This study aimed to examine inter- and intramuscular differences in hamstring muscle damage after a marathon using transverse relaxation time (T2)-weighted magnetic resonance images (MRI). 20 healthy collegiate marathon runners (15 males) were recruited for this study. T2-MRI was performed before (PRE) and at 1 (D1), 3 (D3), and 8 days (D8) after marathon, and the T2 values of each hamstring muscle at the distal, middle, and proximal sites were calculated. Results indicated that no significant intermuscular differences in T2 changes were observed and that, regardless of muscle, the T2 values of the distal and middle sites increased significantly at D1 and D3 and recovered at D8, although those values of the proximal site remained constant. T2 significantly increased at distal and middle sites of the biceps femoris long head on D1 (p = 0.030 and p = 0.004, respectively) and D3 (p = 0.007 and p = 0.041, respectively), distal biceps femoris short head on D1 (p = 0.036), distal semitendinosus on D1 (p = 0.047) and D3 (p = 0.010), middle semitendinosus on D1 (p = 0.005), and distal and middle sites of the semimembranosus on D1 (p = 0.008 and p = 0.040, respectively) and D3 (p = 0.002 and p = 0.018, respectively). These results suggest that the distal and middle sites of the hamstring muscles are more susceptible to damage induced by running a full marathon. Conditioning that focuses on the distal and middle sites of the hamstring muscles may be more useful in improving recovery strategies after prolonged running.

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Biceps brachii muscle hardness assessed by a push-in meter in comparison to ultrasound strain elastography

Murayama, M., Nosaka, K., Inami, T., Shima, N., Yoneda, T.

Scientific Reports (Scientific Reports) Accepted for publication ( 1 ) 2020

Research paper (scientific journal), Joint Work, Accepted

© 2020, The Author(s). This study investigated the relationship between push-in meter (PM) and ultrasound strain elastography (USE) for biceps brachii (BB) muscle hardness. BB hardness of 21 young men was assessed by PM and USE during rest and isometric contractions of six different intensities (15, 30, 45, 60, 75, 90% of maximal voluntary contraction: MVC) at 30°, 60° and 90° elbow flexion. Muscle hardness (E) was calculated from the force–displacement relationship in PM, and strain ratio (SR) between an acoustic coupler (elastic modulus: 22.6 kPa) and different regions of interest (ROIs) in BB was calculated and converted to Young’s modulus (YM) in USE. In resting muscle, E was 26.1 ± 6.4 kPa, and SR and YM for the whole BB was 0.88 ± 0.4 and 30.8 ± 12.8 kPa, respectively. A significant (p < 0.01) correlation was evident between E and logarithmical transformed SR (LTSR) for the ROI of whole BB (r = − 0.626), and E and converted YM (r = 0.615). E increased approximately ninefold from resting to 90% MVC, and E and LTSR (r = − 0.732 to − 0.880), and E and converted YM for the SR above 0.1 were correlated (r = 0.599–0.768, p < 0.01). These results suggest that muscle hardness values obtained by PM and USE are comparable.

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Changes in the linear relationship between muscle contraction intensity and muscle hardness after rectus femoris muscle strain

Inami, T., Shimizu, T., Osuga, T., Narita, T., Hirose, N., Murayama, M.

Case Reports in Orthopedics (Hindawi) 7813217 4 2019.11

Research paper (scientific journal), Joint Work, Accepted

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Stretching combined with repetitive small length changes of the plantar flexors enhances their passive extensibility while not compromising strength

Ikeda, N., Inami, T., Kawakami, Y.

J. Sport Sci. Med. (Journal of Sports Science and Medicine) 18 ( 1 ) 58 - 64 2019

Research paper (scientific journal), Joint Work, Accepted

© Journal of Sports Science and Medicine. Static stretching increases flexibility but can decrease muscle strength; therefore, a method that would avoid the latter has been longed for. In this study, a novel stretching modality was developed that provides repetitive small length changes to the plantar flexor muscles undergoing passive static stretching (minute oscillation stretching). We investigated the effects of minute oscillation stretching on muscle strength and flexibility and its continuance. Isometric plantar flexion strength and maximal ankle joint dorsiflexion angle (dorsiflexion range of motion) were measured in 10 healthy young men (22 ± 2 years) before (pre) and immediately after (post) 3 types of stretching: static stretching, minute oscillation stretching at 15 Hz, and no intervention (control). The dorsiflexion range of motion was also measured at 15, 30, and 60 min post-stretching. Elongation of the medial gastrocnemius and Achilles tendon was determined by ultrasonography. Plantar flexion strength significantly decreased by 4.3 ± 3.5% in static stretching but not in minute oscillation stretching. The dorsiflexion range of motion significantly increased both in static stretching (7.2 ± 8.1%) and minute oscillation stretching (11.2 ± 14.6%), which was accompanied by a significantly larger muscle elongation but not tendon elongation. Elevated dorsiflexion range of motion was maintained until 30 min after minute oscillation stretching, while levels returned to baseline (pre-intervention) 15 min after static stretching. All variables remained unchanged in the control condition. In conclusion, minute oscillation stretching improves extensibility of the muscle belly without decreasing strength. Furthermore, the augmented flexibility to a similar extent to static stretching is retained for 30 min in minute oscillation stretching and within 15 min in static stretching.

Changes in muscle hardness after a full marathon appear different even intramuscularly

Inami, T., Nakagawa, K., Fukano, M., Yonezu, T., Higashihara, A., Iizuka, S., Narita, T., Murayama, M.

J Sports Med Phys Fitness (Minerva Medica) 59 ( 6 ) 1094 - 1096 2019

Research paper (scientific journal), Joint Work, Accepted

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Effects of Self-myofascial Release Using a Foam Roller on Range of Motion and Morphological Changes in Muscle: A Crossover Study

Yoshimura, A., Inami, T., Schleip, R., Mineta, S., Shudo, K., Hirose, N.

J Strength Cond Res (Journal of Strength and Conditioning Research) 35 ( 9 ) 2444 - 2450 2019

Research paper (scientific journal), Joint Work, Accepted, ISSN 10648011

Self-myofascial release using a foam roller (FR) is effective in improving range of motion (ROM) in at least some conditions. However, its mechanism is still unclear. Therefore, this study investigated potential acute muscle morphological changes after the FR intervention and aimed to clarify the mechanism of increases in ROM by the FR intervention. We hypothesized that the FR intervention may increase ROM because of changes in fascicle length (FL) and aponeurosis displacement. This crossover study, involving 22 male university students (21.5 6 1.3 years, 170.6 6 4.0 cm, and 64.1 6 8.9 kg; mean 6 SD), compared the FR intervention targeting the gastrocnemius muscle with the control trial. The outcome measures were maximum passive ankle ROM, morphology of the gastrocnemius muscle (FL and aponeurosis displacement) during passive ankle plantar flexor movement, degree of pain during the FR intervention, and sensation of the triceps surae muscle. Although ROM of both dorsiflexion and plantar flexion increased significantly after the FR intervention (p, 0.01), no significant differences were found in FL and aponeurosis displacement before and after the FR intervention. The mean perception of pain during the FR intervention was rated as “slightly uncomfortable,” corresponding to a 2.3 6 2.4-cm on a 9.5-cm visual analog scale. We found that the FR intervention did not influence the morphology of muscle. It is necessary to investigate other factors related to ROM as the next step of this study.

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Changes in autonomic nervous system activity upon pool water entry in middle-aged and elderly men and women assessed by heart rate variability analysis

Nakagaki, A., Inami, T., Baba, R.

Medicine and Biology Accepted for publication 2019

Research paper (scientific journal), Joint Work, Accepted

Optimum displacement of muscle in relation to thickness for biceps brachii hardness measurement using a push-in meter

Murayama, M., Inami, T., Shima, N., Nosaka, K., Uchiyama, T., Yoneda, T.

Biomed. Physical. Eng. Express (Biomedical Physics and Engineering Express) 5 ( 1 ) 017001 2018

Research paper (scientific journal), Joint Work, Accepted

© 2018 IOP Publishing Ltd. Objective: Muscle hardness measured by a push-in meter is calculated from a force-displacement curve (FDC) based on a two-layer spring model. Since a FDC is not linear, how to set a linear range in the FDC largely affects muscle hardness calculation. The present study investigated the linearity of the FDC to find the best portion relative to muscle thickness (MT) for muscle hardness measurement based on a two-layer spring model. Approach: Forty-seven men (age: 28 ±10 years, height: 176 ±7 cm, body mass: 73 ±11 kg) participated in the present study. Hardness of the biceps brachii muscle was measured at the mid-belly using a push-in meter. The FDC was obtained every 5% up to 50% of the MT, and linear regression equations of ten different portions within the FDC were calculated. The coefficient of determination (R 2 ) of each regression line was compared by ANOVA, and a piecewise linear regression analysis was performed by dividing the identified FDC into three linear segments. Results: One-way ANOVA showed a significant (p < 0.01) main effect in R 2 values of ten regression equations. Post-hoc analyses showed no significant differences in R 2 between 0%-15% MT and 0%-40% MT. While the linearity of the FDC was high between 0%-15% and 0%-40% MT, the highest R 2 value was found at 0%-25% and 0%-30% MT. According to the analysis of three linear segments in the FDC, the mean value of the point between the second and third segments was 28.5 ±4.3% MT. Significance: These results suggested that muscle hardness assessment using a push-in meter should be performed close to 30% MT depth for biceps brachii muscle.

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Unstable rocker shoes promote recovery from marathon-induced muscle damage in novice runners

Nakagawa, K., Inami, T., Yonezu, T., Kenmotsu, Y., Narita, T., Kawakami, Y., Kanosue, K.

Scand. J. Med. Sci. Sports (Scandinavian Journal of Medicine and Science in Sports) 28 ( 2 ) 621 - 629 2018

Research paper (scientific journal), Joint Work, Accepted, ISSN 09057188

© 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd We recently reported that wearing unstable rocker shoes (Masai Barefoot Technology: MBT) may enhance recovery from marathon race-induced fatigue. However, this earlier study only utilized a questionnaire. In this study, we evaluated MBT utilizing objective physiological measures of recovery from marathon-induced muscle damages. Twenty-five university student novice runners were divided into two groups. After running a full marathon, one group wore MBT shoes (MBT group), and the control group (CON) wore ordinary shoes daily for 1 week following the race. We measured maximal isometric joint torque, muscle hardness (real time tissue elastography of the strain ratio) in the lower limb muscles before, immediately after, and 1, 3, and 8 days following the marathon. We calculated the magnitude of recovery by observing the difference in each value between the first measurement and the latter measurements. Results showed that isometric torques in knee flexion recovered at the first day after the race in the MBT group while it did not recover even at the eighth day in the CON group. Muscle hardness in the gastrocnemius and vastus lateralis showed enhanced recovery in the MBT group in comparison with the CON group. Also for muscle hardness in the tibialis anterior and biceps femoris, the timing of recovery was delayed in the CON group. In conclusion, wearing MBT shoes enhanced recovery in lower leg and thigh muscles from muscle damage induced by marathon running.

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A case of fetal heart rate deceleration during maternity swimming

中垣明美, 稲見崇孝, 佐々木美果, 馬場礼三

日本臨床スポーツ医学会誌 26 ( 1 ) 144 - 148 2018

Research paper (scientific journal), Joint Work, Accepted

Tracking of time-dependent changes in muscle hardness after a full marathon

Inami, T., Nakagawa, K., Yonezu, T., Fukano, M., Higashihara, A., Iizuka, S., Abe, T., Narita, T.

J. Strength Cond. Res. (Journal of strength and conditioning research) Accepted for publication ( 12 ) 3431 - 3437 2018

Research paper (scientific journal), Joint Work, Accepted

Inami, T, Nakagawa, K, Yonezu, T, Fukano, M, Higashihara, A, Iizuka, S, Abe, T, and Narita, T. Tracking of time-dependent changes in muscle hardness after a full marathon. J Strength Cond Res 33(12): 3431-3437, 2019-We sought to identify changes in individual muscle hardness after a full marathon and to track time-dependent changes using ultrasound strain elastography (SE). Twenty-one collegiate marathon runners were recruited. Muscle hardness (i.e., strain ratio, SR) was measured using SE for the rectus femoris (RF), vastus lateralis (VL), biceps femoris (BF) long head, tibialis anterior (TA), gastrocnemius medial (GM) head, and soleus (SOL) muscles at the following time points: pre (PRE), immediately post (POST), day-1 (D1), day-3 (D3), and day-8 (D8), after a full marathon. We found that the SR decreased after the full marathon (i.e., the muscle became harder), and that the lowest SR across all measured muscles was observed on D1. Although there was no difference in the magnitude of change in SR between the muscles of the thigh, that of the MG and SOL were significantly larger than that of the TA. Muscle hardness in the vastus lateralis, biceps femoris, and SOL recovered at D8 (i.e., nonsignificant difference from PRE), whereas recovery of rectus femoris and gastrocnemius medial hardness at D8 was not observed. Thus, the degree of change in muscle hardness does not occur uniformly within the lower extremity muscles. In particular, changes in muscle hardness of the TA after a full marathon are small compared with other muscles and time-dependent changes in each muscle vary during recovery. The features of muscle hardness identified in this study will be useful for coaches when mentoring runners on proper forms and for training advisers and therapists who seek to address deficiencies in running.

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Foot posture alteration and recovery following a full marathon run

Fukano, M., Inami, T., Nakagawa, K., Narita, T., Iso, S.

Eur. J. Sports Sci. (European Journal of Sport Science) 18 ( 10 ) 1338 - 1345 2018

Research paper (scientific journal), Joint Work, Accepted, ISSN 17461391

© 2018, © 2018 European College of Sport Science. Prolonged running results in lowering of the foot arch and a low arch is associated with subsequent chronic injuries. Foot posture alteration and recovery following a marathon run remain unknown. Therefore, the present study aimed to evaluate foot posture alteration following a full marathon run. The three-dimensional foot posture data of 11 collegiate runners were obtained using an optical foot scanner system before, and immediately, 1 day, 3 days, and 8 days after a full marathon. The navicular height and arch height ratio significantly decreased from before to immediately, 1 day, 3 days, and 8 days after the marathon (navicular height: before, 44.2 ± 5.0 mm; immediately after, 39.4 ± 5.5 mm; 1 day, 37.7 ± 6.2 mm; 3 days, 38.7 ± 5.5 mm; 8 days, 37.6 ± 5.7 mm; arch height ratio: before, 18.4 ± 1.9; immediately after, 16.5 ± 2.5; 1 day, 15.7 ± 2.5; 3 days, 16.2 ± 2.6; 8 days, 15.6 ± 2.2, P < 0.001, respectively). By contrast, the dorsal height significantly increased from before and immediately after to 1 day after the marathon, and then significantly decreased until 8 days after the marathon (P < 0.001). These results indicate that the recovery patterns of the dorsal and navicular heights following a marathon did not coincide; the dorsal height rose temporally at 1 day after and subsequently decreased, but the navicular height decreased throughout the 8-day period after the marathon. More than one week may be necessary for sufficient foot alignment recovery from marathon-induced changes. .

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The reliability, and discriminative ability of the identification of functional ankle instability questionnaire, Japanese version.

Mineta, S., Inami, T., Fukano, M., Hoshiba, T., Masuda, Y., Yoshimura, A., Kumai, T., Hirose, N.

Phys. Ther. Sport (Physical Therapy in Sport) Accepted for publication 1 - 6 2018

Research paper (scientific journal), Accepted, ISSN 1466853X

© 2018 Elsevier Ltd Objective: To assess the discriminability as well as the reliability, and internal consistency of the Identification of Functional Ankle Instability questionnaire translated into Japanese (IdFAI-J). Design: Cross-sectional study. Setting: Collegiate athletic training/sports medicine clinic. Participants: Twenty bilingual and sixty-five collegiate athletes including participants with and without functional instability (FI). Main outcome measures: The sensitivity, specificity, test retest reliability, and internal consistency of IdFAI-J. Results: The optimal cutoff score between the FI and non-FI participants was >10, with an area under the curve of 0.92. We calculated high sensitivity (0.94) and specificity (0.77) at the cutoff point. For the test-retest reliability, the intraclass correlation coefficient value of the IdFAI-J was 0.96; the standard error of measurement and minimal detectable change value was 1.69 and 3.60, respectively. Cronbach's α was 0.87; there was no improvement when a particular item was deleted from the scale. Conclusions: The IdFAI-J has excellent discriminability, test-retest reliability, and internal consistency. Hence, the IdFAI-J significantly contribute to clinical practice and future research related to ankle instability in Japan.

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High lateral plantar pressure is related to an increased tibialis anterior/fibulalis longus activity ratio in patients with recurrent lateral ankle sprain

Mineta, S., Inami, T., Mariano, R., Hires, N.

Open Access J. Sports Med. 8 123 - 131 2017

Research paper (scientific journal), Joint Work, Accepted

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Anatomical cross-sectional area of the quadriceps femoris and sit-to-stand test score in middle-aged and elderly population: Development of a predictive equation

Saito, A., Ema, R., Inami, T., Maeo, S., Otsuka, S., Higuchi, M., Shibata, S., Kawakami, Y.

J. Physiol. Anthropol. 36 3 2017

Research paper (scientific journal), Joint Work, Accepted

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The change in muscle hardness after static stretching evaluated by different ultrasound elastography techniques may be equivalent

Inami, T., Shimizu, T.

J. Sports Med. Phys. Fit. 57 161 - 162 2017

Research paper (scientific journal), Joint Work, Accepted

Relationship between isometric contraction intensity and muscle hardness assessed by ultrasound strain elastography

Inami, T., Tsujimura, T., Shimizu, T., Watanabe, T., Lau, W. Y., Nosaka, K.

Eur. J. Appl. Physiol. 117 ( 5 ) 843 - 852 2017

Research paper (scientific journal), Joint Work, Accepted

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Difference in fascicle behaviors between superficial and deep quadriceps muscles during isometric contractions

Ando, R., Nosaka, K., Inami, T., Tomita, A., Watanabe, K., Blazevich, A., Akima, H.

Muscle Nerve 53 797 - 802 2016

Research paper (scientific journal), Joint Work, Accepted

The relationship between changes in flexibility and total peripheral vascular function in older adults

Inami, T., Baba, R., Nakagaki, A., Shimizu, T.

Gazz. Med. Ital. Arch. Sci. Med. 175 ( 11 ) 496 - 497 2016

Research paper (scientific journal), Joint Work, Accepted

Differences in autonomic neural activity during exercise between the second and third trimester of pregnancy

Nakagaki, A., Inami, T., Minoura, T., Baba, R., Iwase, S., Sato, M.

J. Obstet. Gynaecol. Res. 42 951 - 959 2016

Research paper (scientific journal), Joint Work, Accepted

Assessment of individual muscle hardness and stiffness using ultrasound elastography

Inami, T., Kawakami, Y.

J. Phys. Fitness Sport Med. 5 313 - 317 2016

Research paper (scientific journal), Joint Work, Accepted

大腿四頭筋に対する伸張性収縮後のMRI T2値と超音波エラストグラフィによる筋硬度の関係について

INAMI Takayuki

日本運動生理学雑誌 23 ( 2 ) 37 - 44 2016

Research paper (scientific journal), Joint Work, Accepted

ひずみエラストグラフィによる筋硬度と筋損傷指標との関係

INAMI Takayuki

トレーニング科学 27 ( 4 ) 101 - 109 2016

Research paper (scientific journal), Joint Work, Accepted

静的ストレッチングとランニングを組み合わせたウォームアップが跳躍能力に及ぼす影響

INAMI Takayuki

トレーニング科学 27 ( 4 ) 123 - 132 2016

Research paper (scientific journal), Joint Work, Accepted

Acute changes in peripheral vascular tonus and systemic circulation during static stretching

Inami, T., Baba, R., Nakagaki, A., Shimizu, T.

Res. Sport Med. 23 ( 2 ) 167 - 178 2015

Research paper (scientific journal), Joint Work, Accepted

The relationship between muscle-tendon unit stiffness and muscle hardness of the gastrocnemius muscle using ultrasound real-time tissue elastography

Inami, T., Shimizu, T.

Gazz. Med. Ital. Arch. Sci. Med. 174 ( 10 ) 459 - 466 2015

Research paper (scientific journal), Joint Work, Accepted

Acute changes in autonomic nerve activity during passive static stretching

Inami, T., Shimizu, T., Baba, R., Nakagaki, A.

Am. J. Sport Sci. Med. 2 ( 4 ) 166 - 170 2014

Research paper (scientific journal), Joint Work, Accepted

妊婦水泳教室への参加回数が妊娠36週以降の妊娠経過や新生児の出生児体重に及ぼす影響初産婦における検討

INAMI Takayuki

日本臨床スポーツ医学会誌 22 ( 2 ) 290 - 296 2014

Research paper (scientific journal), Joint Work, Accepted

ヒト骨格筋における超音波エラストグラフィの基礎理論と臨床応用

INAMI Takayuki

日本整形外科スポーツ医学会会誌 34 ( 1 ) 2 - 10 2014

Research paper (scientific journal), Joint Work, Accepted

Long-term stretching program in older active adults increases muscle strength

Inami, T., Shimizu, T.

J. Exerc. Sports Orthop. 1 ( 2 ) 1 - 8 2014

Research paper (scientific journal), Accepted

Ultrasound Elastographyによる筋出力発揮における筋硬度変化の半定量的評価

INAMI Takayuki

日本整形外科超音波学会雑誌 24 ( 1 ) 32 - 37 2013

Research paper (scientific journal), Joint Work, Accepted

Analyzing elderly women’s autonomic nervous system activity through heart rate variability during aquatic exercise: Four hypertensive cases.

Nakagaki, A., Inami, T., Baba, R., Iwase, S.

Med. Biol. 157 239 - 246 2013

Research paper (scientific journal), Accepted

筋の形態学的および機能的考察を行った陳旧性大腿直筋肉ばなれの一症例

INAMI Takayuki

日本臨床スポーツ医学会誌 20 ( 2 ) 364 - 369 2012

Research paper (scientific journal), Joint Work, Accepted

バスケットボールのジャンプシュート動作における動的関節位の肉眼判定に関する研究

INAMI Takayuki

中京大学体育学論叢 53 ( 1 ) 7 - 18 2012

Research paper (bulletin of university, research institution), Joint Work, Accepted

Reconsideration of grip strength measurement: Focusing on bi-articular and multi-articular muscles

Inami, T., Miyagawa, H., Inoue, M., Shimizu, T., Nakagawa, T., Takayanagi, F., Niwa, S.

Med. Biol. 156 62 - 69 2012

Research paper (scientific journal), Joint Work, Accepted

The relationship between autonomic activities of pregnant women and fetal heart rate during maternity swimming

Nakagaki, A., Baba, R., Inami, T., Sasaki, M., Iwa, T., Watanabe, K., Iwase, S.

J. Physiol. Sci. 62 207 - 208 2012

Research paper (scientific journal), Joint Work, Accepted

妊婦水泳の継続が妊娠経過におよぼす影響　妊娠23週前後開始の長期群と24週後開始の短期群との比較

INAMI Takayuki

医学と生物学 155 ( 12 ) 943 - 948 2011

Research paper (scientific journal), Joint Work, Accepted

運動療育センター妊婦水泳12年間の傾向と今後の課題

INAMI Takayuki

母性看護 41 15 - 17 2011

Research paper (conference, symposium, etc.), Joint Work, Accepted

心拍変動解析によるマタニティスイミング中の自律神経活動の変化

INAMI Takayuki

医学と生物学 155 ( 8 ) 531 - 537 2011

Research paper (scientific journal), Joint Work, Accepted

ストレッチングが自律神経活動，末梢血管抵抗，全身循環応答に及ぼす影響

INAMI Takayuki

医学と生物学 155 ( 9 ) 577 - 587 2011

Research paper (scientific journal), Joint Work, Accepted

前十字靱帯再建例に対する能動型歩行訓練器の効果 ‐自由歩行に及ぼす影響を運動力学的に検討‐

INAMI Takayuki

東海スポーツ傷害研究会会誌 29 28 - 30 2011

Research paper (conference, symposium, etc.), Joint Work, Accepted

非妊娠成人女性の妊婦水泳プログラムにおける自律神経活動 - 更年期前女性の年齢との関連性の検討-

INAMI Takayuki

愛知医科大学看護学部紀要 10 25 - 31 2011

Research paper (bulletin of university, research institution), Joint Work, Accepted

能動型歩行訓練器の自由歩行に及ぼす影響　前十字靱帯再建例への応用

INAMI Takayuki

東海スポーツ傷害研究会会誌 28 25 - 27 2010

Research paper (conference, symposium, etc.), Joint Work, Accepted

Movement of gastrocnemius muscle tendon by ankle joint passive plantar/dorsiflexion exercise. Changes by knee joint flexion angle

Inami, T., Shimizu, T., Woo, C. Y., Mizuno, T., Miyagawa, H., Inoue, M., Nakagawa, T., Takayanagi, F., Niwa, S.

Gazz. Med. Ital. Arch. Sci. Med. 169 ( 4 ) 121 - 130 2010

Research paper (scientific journal), Joint Work, Accepted

Amount of displacement of the gastrocnemius muscle-tendon junction following retention of passive dorsiflexion of the ankle joint: Investigation using different knee joint angles

Inami, T., Shimizu, T., Miyagawa, H., Inoue, M., Nakagawa, T., Takayanagi, F., Niwa, S.

J. Orthop. Sports Med. 30 ( 3 ) 190 - 196 2010

Research paper (scientific journal), Joint Work, Accepted

Follow-up study of the effect of intervention with stretching

Inami, T., Shimizu, T., Nakata, M., Kajiura, H., Miyagawa, H., Hasegawa, T., Inoue, M., Gotou, M., Hasegawa, R., Fukuta, S., Takayanagi, F., Nakagawa, T., Niwa, S.

Med. Biol. 154 ( 4 ) 201 - 211 2010

Research paper (scientific journal), Joint Work, Accepted

マイルド加温（温熱ストレス）が筋力増強訓練の短期効果に及ぼす影響

INAMI Takayuki

日本臨床スポーツ医学会誌 18 ( 3 ) 428 - 434 2010

Research paper (scientific journal), Joint Work, Accepted

下腿三頭筋に対する二種の他動的stretchingが足関節背屈角度に及ぼす影響

INAMI Takayuki

体力科学 59 ( 5 ) 549 - 554 2010

Research paper (scientific journal), Joint Work, Accepted

Influence of various passive triceps surae stretching techniques on muscle strength

Inami, T., Shimizu, T., Miyagawa, H., Inoue, M., Nakagawa, T., Takayanagi, F., Niwa, S.

J. Orhop. Sports Med. 29 ( 3 ) 168 - 172 2009

Research paper (scientific journal), Joint Work, Accepted

高校サッカー選手に対する“stabilization exercise”の短期効果とその限界

INAMI Takayuki

中京大学体育学論叢 50 ( 1 ) 13 - 22 2009

Research paper (bulletin of university, research institution), Joint Work, Accepted

膝教室における大腿四頭筋機能訓練法

INAMI Takayuki

運動・物理療法 19 ( 1 ) 42 - 49 2008

Research paper (scientific journal), Joint Work, Accepted

二関節筋に対するストレッチングが等速性筋出力に及ぼす影響

INAMI Takayuki

日本臨床スポーツ医学会誌 16 ( 3 ) 395 - 401 2008

Research paper (scientific journal), Joint Work, Accepted

中高齢者の下肢筋力増強訓練に関する研究

INAMI Takayuki

愛知医科大学医学会雑誌 35 ( 1 ) 39 - 48 2007

Research paper (bulletin of university, research institution), Joint Work, Accepted

二関節筋に対するストレッチング方法の違いが筋出力に与える影響

INAMI Takayuki

中京大学体育学論叢 48 ( 3 ) 1 - 7 2007

Research paper (bulletin of university, research institution), Joint Work, Accepted

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