Biwako Seikei Sport College

The aim of this study was to investigate the effects of body weight resistance training with slow movement and tonic force generation on muscle deoxygenation during arterial occlusion at rest. Eleven untrained healthy young male subjects performed Bulgarian split squat training for 3days per week for 8weeks. Each training session consisted of 4 sets of 10 repetitions (or until volitional failure). Before and after training, with the subject at rest in supine position, a pneumatic cuff was placed at the proximal site of the thigh and inflated to 250mmHg to induce the occlusion of arterial blood flow. During arterial occlusion, in the thigh distal to the cuff, muscle O2 saturation (SmO2) was continuously monitored at the vastus lateralis (VL) and rectus femoris (RF) muscles using spatially resolved near-infrared spectroscopy. During occlusion, the slope of desaturation and area above the curve (AAC) from baseline values were evaluated. At VL, a significantly shallower desaturation slope was found after training, compared to before. As a result, AAC from baseline was significantly lower after training. In contrast, no significant changes in the desaturation slope or AAC were observed at RF. Body weight resistance training for 8weeks may cause a shallow desaturation slope during arterial occlusion at rest, though the effects of resistance training on desaturation response during arterial occlusion may be regional in quadriceps muscles.

Abstract Sprint performance plays a crucial role in various sports. Short sprints vary in court size and competitive characteristics but are common in many sports. Although the relationship between age and muscle strength has been explored in short sprints, there is limited understanding of how various physical factors interact, particularly concerning differences in the acceleration phase. This study examined the relationship between sprint times at 0‒2.5 m, 2.5‒5 m, and 5‒10 m intervals and various factors in junior athletes. Results indicated that sprint times increased with age, and is correlated with muscle strength and flexibility. Partial correlation analysis showed that faster times in the 0‒2.5 m interval were associated with higher hip flexibility; in the 2.5‒5 m interval, faster times were associated with higher core flexibility; and in the 5‒10 m interval, a relationship with standing long jump performance was confirmed. Furthermore, lower fat-free body weight translated to higher performance. In the acceleration phase of 10 m, flexibility immediately after the start and the subsequent horizontal propulsive force is important factors that are strongly related to performance change in each interval. The study results illuminate the mechanism behind short sprints in junior athletes and emphasize the importance of daily training, considering the sprint distance required for each sport.

The aim of this study was to investigate the skeletal muscle O2 dynamics during body-weight resistance exercise with slow movement and tonic force generation. Thirteen untrained, healthy, young males performed Bulgarian split squats and push-ups until volitional failure. Relative changes from rest in oxygenated haemoglobin (oxy-Hb) and deoxygenated haemoglobin (deoxy-Hb) concentrations were continuously monitored at the vastus lateralis (VL) and rectus femoris (RF) muscles during squats, and pectoralis major (PM) and triceps brachii (TB) muscles during push-ups using spatial resolved near-infrared spectroscopy oximetry. During the squat exercise, deoxy-Hb continuously increased at RF until failure (10.8±7.0μmol/L), while at VL, deoxy-Hb was relatively maintained during 25-100% of the number of maximum repetitions (18.0±7.4μmol/L at volitional failure). During the push-up exercise, a significant increase in deoxy-Hb was observed during exercise from rest at PM and TB. We found a significant increase in oxy-Hb during exercise at PM (28.1±15.8μmol/L at volitional failure), while at TB, no significant difference was observed from rest (-2.7±13.7μmol/L at volitional failure). Our findings suggest that the deoxygenation patterns during body-weight squat exercise were heterogeneous within the quadriceps muscles. Moreover, differences in O2 dynamics between the trunk and extremity muscles may be partly explained by convective O2 supply during resistance exercise. However, future studies are needed due to inter-individual differences in skills for body-weight resistance exercise.

琵琶湖北湖の水深50～90 mの深底部に位置する3地点で1992年から2019年までに行った底生動物の定量調査の結果を示した。底生動物群集で優占した動物群は3地点とも貧毛類で，なかでも，個体数ではイトミミズが，現存量ではエラミミズが多くを占めた。同一地点での底生動物の総密度や総個体数には，期間中，増加あるいは減少の明瞭な変化はみられなかった。一方，底生動物や貧毛類の密度や現存量は，第1湖盆中央部（水深90 m地点）で最も低く，次いで第2湖盆中央部（水深70 m地点），その周縁部（水深50 m地点）の順だった。湖底直上水の溶存酸素濃度も，全調査期間および循環期前の期間を通じて第1湖盆中央部で最も低く，次いで第2湖盆中央部，その周縁部の順だった。このことは，湖底直上水の溶存酸素濃度が底生動物の密度や現存量に対して長期的な影響を与えていたことを示唆している。

ABSTRACT The purpose of the present study was to investigate the effects of using a combination of static stretching and aerobic exercise on muscle tendon unit stiffness and muscle strength in the ankle plantar-flexor muscles. Fifteen healthy males (23.3 ± 2.7 years, 170.3 ± 6.5 cm, 64.9 ± 8.7 kg) received three different interventions, in random order. Intervention 1 received 10 min of aerobic exercise after five cycles of one minute of static stretching. Intervention 2 received 10 min of aerobic exercise before the static stretching. Intervention 3 received 5 min of aerobic exercise both before and after the static stretching. The range of motion of ankle dorsiflexion, stretch tolerance, muscle tendon unit stiffness, peak torque of ankle plantarflexion, and the amplitude of electromyography were measured. In all interventions, the range of motion and stretch tolerance significantly increased (p < 0.05), but muscle tendon unit stiffness decreased significantly for all interventions (p < 0.05). Peak torque of ankle plantar flexion and amplitude of electromyography significantly increased for Interventions 1 and 3 (p < 0.05), while these significantly decreased for Intervention 2 (p < 0.05). These data indicated that range of motion and stretch tolerance were increased, but muscle tendon unit stiffness was decreased regardless of the order of static stretching and aerobic exercise. Aerobic exercise after static stretching increased the peak torque and amplitude of electromyography.

The purposes of this study were ①to clarify the psychological transformation process through cheering activities based on the narrative of a reserve college student athlete engaged in team cheering activities, and

BackgroundAltitude training has often been conducted just before main competition games in many sports. An increase in the frequency of upper respiratory tract infections and gastrointestinal infections due to an altitude-induced suppression of the immune system has been reported after altitude training. Salivary secretory immunoglobulin A (SIgA) is the major immunoglobulin of the mucosal immune system. A suppressive effect of heavy training on SIgA has been reported. However, little is known regarding the effects of repetitive altitude training and hypoxic exposure on SIgA. The objective of this study was to evaluate the changes in SIgA in swimmers undergoing repetitive altitude training at 1,900 m.MethodsNine collegiate swimmers who experienced their first altitude training experience (FT group) were compared to nine swimmers who experienced repetitive training (RT group) and non-training subjects (Con group). Saliva was collected before ascent and eight times every 2 days during altitude training. SIgA levels were measured by enzyme-linked immunosorbent assays.ResultsCompared to the Con group, SIgA levels and the secretion velocity were decreased after ascent and were slowly restored in both the FT and RT groups. The chronological trends in SIgA levels were similar, even though the decline in SIgA levels in the FT group was larger than that in the RT group.ConclusionAltitude training and experience with altitude training may be one of the factors influencing SIgA.