Department of Human Studies, University of Alabama at Birmingham, 901 South 13th Street, Birmingham, AL 35294-1250, USA.
Eur J Appl Physiol. 2011 Apr;111(4):715-23. doi: 10.1007/s00421-010-1694-1. Epub 2010 Oct 23.
Aging is associated with loss of endurance; however, aging is also associated with decreased fatigue during maximal isometric contractions. The aims of this study were to examine the relationship between age and walking endurance (WE) and maximal isometric fatigue (MIF) and to determine which metabolic/fitness components explain the expected age effects on WE and MIF. Subjects were 96 pre-menopausal women. Oxygen uptake (walking economy) was assessed during a 3-mph walk; aerobic capacity and WE by progressive treadmill test; knee extension strength by isometric contractions, MIF during a 90-s isometric plantar flexion (muscle metabolism measured by (31)P MRS). Age was related to increased walking economy (low VO(2), r = -0.19, P < 0.03) and muscle metabolic economy (force/ATP, 0.34, P = 0.01), and reduced MIF (-0.26, P < 0.03). However, age was associated with reduced WE (-0.28, P < 0.01). Multiple regression showed that muscle metabolic economy explained the age-related decrease in MIF (partial r for MIF and age -0.13, P = 0.35) whereas walking economy did not explain the age-related decrease in WE (partial r for WE and age -0.25, P < 0.02). Inclusion of VO(2max) and knee endurance strength accounted for the age-related decreased WE (partial r for WE and age = 0.03, P > 0.80). In premenopausal women, age is related to WE and MIF. In addition, these results support the hypothesis that age-related increases in metabolic economy may decrease MIF. However, decreased muscle strength and oxidative capacity are related to WE.
衰老与耐力丧失有关；然而，衰老也与最大等长收缩时疲劳减少有关。本研究的目的是探讨年龄与步行耐力（WE）和最大等长疲劳（MIF）的关系，并确定哪些代谢/体能成分可以解释年龄对 WE 和 MIF 的预期影响。研究对象为 96 名绝经前女性。通过 3 英里/小时的步行评估摄氧量（步行经济性）；通过渐进式跑步机测试评估有氧能力和 WE；通过等长收缩评估膝关节伸展力量；通过（31）P MRS 测量等长跖屈时的 MIF（肌肉代谢）。年龄与步行经济性增加（低 VO2，r = -0.19，P < 0.03）和肌肉代谢经济性（力/ATP，0.34，P = 0.01）相关，与 MIF 减少（-0.26，P < 0.03）相关。然而，年龄与 WE 减少（-0.28，P < 0.01）相关。多元回归显示，肌肉代谢经济性解释了 MIF 的年龄相关下降（MIF 和年龄的部分 r 为-0.13，P = 0.35），而步行经济性不能解释 WE 的年龄相关下降（WE 和年龄的部分 r 为-0.25，P < 0.02）。包括 VO2max 和膝关节耐力强度可以解释 WE 的年龄相关下降（WE 和年龄的部分 r 为 0.03，P > 0.80）。在绝经前女性中，年龄与 WE 和 MIF 相关。此外，这些结果支持这样一种假设，即与年龄相关的代谢经济性增加可能会降低 MIF。然而，肌肉力量和氧化能力的下降与 WE 有关。
