森 寿仁

PURPOSE: We hypothesized that respiratory muscle endurance training (RMET) in hypoxia induces greater improvements in respiratory muscle endurance with attenuated respiratory muscle metaboreflex and consequent whole-body performance. We evaluated respiratory muscle endurance and cardiovascular response during hyperpnoea and whole-body running performance before and after RMET in normoxia and hypoxia. METHODS: Twenty-one collegiate endurance runners were assigned to control (n = 7), normoxic (n = 7), and hypoxic (n = 7) groups. Before and after the 6 wk of RMET, incremental respiratory endurance test and constant exercise tests were performed. The constant exercise test was performed on a treadmill at 95% of the individual's peak oxygen uptake (V˙O2peak). The RMET was isocapnic hyperpnoea under normoxic and hypoxic conditions (30 min·d). The initial target of minute ventilation during RMET was set to 50% of the individual maximal voluntary ventilation, and the target increased progressively during the 6 wk. Target arterial oxygen saturation in the hypoxic group was set to 90% in the first 2 wk, and thereafter it was set to 80%. RESULTS: Respiratory muscle endurance was increased after RMET in the normoxic and hypoxic groups. The time to exhaustion at 95% V˙O2peak exercise also increased after RMET in the normoxic (10.2 ± 2.4 to 11.2 ± 2.6 min) and hypoxic (11.5 ± 2.6 to 12.6 ± 3.0 min) groups, but not in the control group (9.6 ± 3.2 to 9.4 ± 4.0 min). The magnitude of these changes did not differ between the normoxic and the hypoxic groups (P = 0.84). CONCLUSION: These results suggest that the improvement of respiratory muscle endurance and blunted respiratory muscle metaboreflex could, in part, contribute to improved endurance performance in endurance-trained athletes. However, it is also suggested that there are no additional effects when the RMET is performed in hypoxia.

&nbsp;&nbsp;The main purpose of this study was to investigate anthropometry and body composition in 26 male ultramountain runners who participated in Trans Japan Alps Race 2014, a multi-stage ultramountain running race over 415 km to be covered within 5-8 days. The second purpose was to investigate the changes in skinfold thickness during the race. Before the race, all participants were examined in terms of body weight, BMI, skinfold thickness at 8 sites and estimated percentage body fat. In addition, the finishers (n=14) were re-examined in the post-race period. The main findings are summarized below.<br> 1.&nbsp;&nbsp;The participants had a mean (&plusmn;SD) body weight of 62.3&plusmn;5.1 kg, a BMI of 21.5&plusmn;1.4 kg/m², a sum of 8 skinfold thickness of 57.7&plusmn;15.5 mm, and an estimated percentage body fat of 12.0&plusmn;2.4%. There were no significant differences in any parameters between the finishers and the non-finishers.<br> 2.&nbsp;&nbsp;The sum of 8 skinfold thickness in the finishers was significantly reduced by 11.3% after the race (Pre : 55.0&plusmn;13.6 mm, Post : 48.8&plusmn;12.1 mm), representing a dramatic response in comparison with a previous study that investigated ultramarathon runners in a 100-km ultramarathon race (0.9%).<br>

3000m台の高度で重度の急性高山病(AMS)を発症しやすい登山者2例(A、T)を対象とした低酸素順化トレーニングの効果について検討した。2ヵ月間で4回の低酸素トレーニングを実施した(1泊2日を3回、2泊3日を1回)。Aにおいて、仮眠時のSpO2は、2回目に一旦低下がみられたが、3回目、4回目と上昇する傾向を認めた。これらの値の変化は、仮眠時のAMSスコアの変化とも連動し、「4回目のトレーニング時に著しく体調が良いように感じた」という、観察所見とも一致した。Tでは、登山をした際のAMSの特徴は、行動中に頭痛、めまい、ふらつきを感じることが多く、トレーニング中のAMSスコアをみると、椅座位安静時や仮眠時と比較して、運動時にはやや高値を示していた。トレーニング4回目には運動時のSpO2にも増加を認め、観察所見でも、「4回目には体調が著しく良くなっている」という結果であった。