Department of Nutrition and Human Sciences, University of Nebraska-Lincoln, Lincoln, NE, 68510, USA.
Department of Health, Kinesiology and Sport, University of South Alabama, Mobile, AL, 36688, USA.
Eur J Appl Physiol. 2021 Aug;121(8):2243-2252. doi: 10.1007/s00421-021-04694-5. Epub 2021 Apr 24.
The purpose of this study was to examine the composite, intra-individual, and inter-individual patterns of responses for deoxygenated hemoglobin and myoglobin (deoxy[heme]), oxygenated hemoglobin and myoglobin (oxy[heme]), total hemoglobin and myoglobin (total[heme]), and tissue saturation index (StO%) during fatiguing, maximal, isokinetic, unilateral, and bilateral leg extensions.
Nine men (Mean ± SD; age = 21.9 ± 2.4 years; height = 181.8 ± 11.9 cm; body mass = 85.8 ± 6.2 kg) performed 50 unilateral and bilateral maximal, concentric, isokinetic leg extensions at 180° s on two separate visits. The muscle oxygenation parameters assessed with near-infrared spectroscopy from the dominant leg and isokinetic torque were averaged for 2 consecutive repetitions at 5 repetition intervals. Separate 2 (Condition [Unilateral and Bilateral]) × 10 (Repetition [5-50]) repeated measures ANOVAs were performed to examine mean differences for normalized isokinetic torque and each muscle oxygenation parameter. Intra- and inter-individual differences were examined with polynomial regression analyses.
For normalized isokinetic torque, the unilateral condition (56.3 ± 10.5%) exhibited greater performance fatigability than the bilateral condition (45.0 ± 18.7%). Collapsed across Condition, deoxy[heme] exhibited an increase (p < 0.001), while StO% exhibited a decrease (p < 0.001). The bilateral condition exhibited a more sustained decline in oxy[heme] than the unilateral condition (p = 0.005). Deoxy[heme], oxy[heme], and total[heme] exhibited substantial intra- and inter-individual differences for the fatigue-induced patterns of response.
The present findings indicated that the greater performance fatigability for unilateral versus bilateral fatiguing, maximal, isokinetic leg extensions was not attributable to differences in muscle oxygenation. Future studies of muscle oxygenation should report individual and composite fatigue-induced patterns of responses due to the substantial intra- and inter-individual variabilities.
本研究旨在探讨去氧血红蛋白和肌红蛋白（脱氧[血红素]）、氧合血红蛋白和肌红蛋白（氧合[血红素]）、总血红蛋白和肌红蛋白（总[血红素]）以及组织饱和度指数（StO%）在疲劳、最大、等速、单侧和双侧腿伸展过程中的综合、个体内和个体间的反应模式。
9 名男性（平均值 ± 标准差；年龄 = 21.9 ± 2.4 岁；身高 = 181.8 ± 11.9 厘米；体重 = 85.8 ± 6.2 千克）在两次单独的访问中，分别进行了 50 次单侧和双侧最大、向心、等速腿伸展运动，角速度为 180°/s。用近红外光谱仪从优势腿评估的肌肉氧合参数和等速扭矩在 5 次重复间隔的 2 次连续重复中平均。分别进行了 2（条件[单侧和双侧]） × 10（重复[5-50]）重复测量方差分析，以检查归一化等速扭矩和每个肌肉氧合参数的平均差异。用多项式回归分析检查个体内和个体间的差异。
对于归一化等速扭矩，单侧条件（56.3 ± 10.5%）的表现疲劳性比双侧条件（45.0 ± 18.7%）更强。在合并条件下，脱氧[血红素]呈增加趋势（p < 0.001），而 StO%呈下降趋势（p < 0.001）。与单侧条件相比，双侧条件的氧合[血红素]下降更为持续（p = 0.005）。脱氧[血红素]、氧合[血红素]和总[血红素]在疲劳诱导的反应模式方面表现出显著的个体内和个体间差异。
本研究结果表明，与疲劳、最大、等速腿伸展的双侧相比，单侧的表现疲劳性更强，这并不是由于肌肉氧合的差异所致。由于个体内和个体间的变异性很大，未来的肌肉氧合研究应该报告个体和综合疲劳诱导的反应模式。
