Myers Christopher M, Kim Jeong-Su, Musilli Megan, McCully Kevin, Florian John P
Department of Nutrition, Food and Exercise Sciences, Florida State University, Tallahassee, FL, United States.
United States Navy Experimental Diving Unit, Panama City Beach, FL, United States.
Front Physiol. 2018 Jul 27;9:977. doi: 10.3389/fphys.2018.00977. eCollection 2018.
This study examined the effects of repeated long-duration water immersions (WI)s at 1.35 atmospheres absolute (ATA) on neuromuscular endurance performance. We hypothesized that, following 5 days of consecutive, resting, long-duration WIs, neuromuscular endurance performance would decrease. Fifteen well-trained, male subjects completed five consecutive 6-h resting WIs with 18-h surface intervals during the dive week while breathing compressed air at 1.35 ATA. Skeletal muscle endurance performance was assessed before and after each WI, and 24 and 72 h after the final WI. Muscular endurance assessments included 40% maximum handgrip endurance (MHE) and 50-repetition maximal isokinetic knee extensions. Near infrared spectroscopy was used to measure muscle oxidative capacity of the vastus lateralis and localized muscle tissue oxygenation of the vastus lateralis and flexor carpi radialis. Simultaneously, brachioradialis neuromuscular activation was measured by surface electromyography. A 24.9% increase ( = 0.04) in the muscle oxidative capacity rate constant () occurred on WI 4 compared to baseline. No changes occurred in 40% MHE time to exhaustion or rate of fatigue or total work performed for the 50-repetition maximal isokinetic knee extension. The first quartile of deoxygenated hemoglobin concentration showed a 6 and 35% increase on WIs 3 and 5 ( = 0.026) with second quartile increases of 9 and 32% on WIs 3 and 5 ( = 0.049) during the 40% MHE testing when compared to WI 1. Our specific WI protocol resulted in no change to muscular endurance and oxygen kinetics in load bearing and non-load bearing muscles.
本研究考察了在绝对气压1.35个大气压（ATA）下重复进行长时间水浸（WI）对神经肌肉耐力表现的影响。我们假设，在连续5天进行静息状态下的长时间水浸后，神经肌肉耐力表现会下降。15名训练有素的男性受试者在潜水周期间，于1.35 ATA的压缩空气中呼吸，连续进行了5次每次6小时的静息水浸，每次水浸之间有18小时的体表间隔。在每次水浸前后以及最后一次水浸后的24小时和72小时评估骨骼肌耐力表现。肌肉耐力评估包括40%最大握力耐力（MHE）和50次重复的最大等速膝关节伸展。使用近红外光谱法测量股外侧肌的肌肉氧化能力以及股外侧肌和桡侧腕屈肌的局部肌肉组织氧合情况。同时，通过表面肌电图测量肱桡肌的神经肌肉激活情况。与基线相比，在第4次水浸时肌肉氧化能力速率常数（ ）增加了24.9%（ = 0.04）。对于50次重复的最大等速膝关节伸展，40% MHE的疲劳时间、疲劳速率或总功均未发生变化。在进行40% MHE测试时，与第1次水浸相比，脱氧血红蛋白浓度的第一个四分位数在第3次和第5次水浸时分别增加了6%和35%（ = 0.026），第二个四分位数在第3次和第5次水浸时分别增加了9%和32%（ = 0.049）。我们特定的水浸方案对承重和非承重肌肉的肌肉耐力和氧动力学没有产生变化。
