研究者詳細 - 山口　翔大

山口　翔大（ヤマグチ　ショウタ）

Yamaguchi, Shota

写真a

所属（所属キャンパス）: 研究所・センター等体育研究所（日吉）

職名: 特任助教（有期）

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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年

ISSN 02640414

　概要を見る

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.
- Access to Document (DOI)
Changes in urinary titin N-terminal fragments as a biomarker of exercise-induced muscle damage in the repeated bout effect

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

Journal of Science and Medicine in Sport （Journal of Science and Medicine in Sport） 23 （ 6 ） 536 - 540 2020年06月

ISSN 14402440

　概要を見る

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.
- Access to Document (DOI)
Effects of rest interval array on training volume, perceived exertion, neuromuscular fatigue, and metabolic responses during agonist-antagonist muscle alternative training

Zhao H., Yamaguchi S., Okada J.

Journal of Sports Medicine and Physical Fitness （Journal of Sports Medicine and Physical Fitness） 60 （ 4 ） 536 - 543 2020年04月

ISSN 00224707

　概要を見る

BACKGROUND: Agonist-antagonist muscle superset (SS) and paired-set (PS) strength training protocols enable the completion of training activities within a shorter period of time than traditional set. The purpose of this study was to investigate the effects of PS and SS through total volume (TV), set volume (SV), blood lactate concentration (LAC), rating of perceived exertion (RPE), and neuromuscular fatigue index (FInsm5). METHODS: Eleven males who train recreationally performed PS and SS consisting of bent-over row (BOR) and bench press (BP). In performing the PS, a single bout of BOR was followed by a rest interval of 60 seconds, the BP was then performed and followed by another rest interval of 60 seconds. When the SS was performed, a single bout of BOR and a single bout of BP were performed consecutively and followed by a single rest interval of 120 seconds. The exercise configurations were repeated until five sets were completed. The TV was calculated by multiplying the number of successful repetitions and the load. The LAC and RPE were measured at predetermined times. Electromyographic signals were recorded for use in the FInsm5 calculation. RESULTS: The RPE indicated that PS was significantly lower than SS (P<0.01). No significant differences between PS and SS were discovered in SV, TV, LAC, and FInsm5. CONCLUSIONS: This study demonstrates that PS has lower perceived exertion than SS when agonist-antagonist strength training protocols are selected as the training structure.
- Access to Document (DOI)
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年03月

　概要を見る

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.