Department of Exercise Sciences, Brigham Young University, Provo, Utah, USA.
Program of Gerontology, Brigham Young University, Provo, Utah, USA.
Exp Physiol. 2024 Feb;109(2):240-254. doi: 10.1113/EP091571. Epub 2023 Nov 7.
Ageing results in lower exercise tolerance, manifested as decreased critical power (CP). We examined whether the age-related decrease in CP occurs independently of changes in muscle mass and whether it is related to impaired vascular function. Ten older (63.1 ± 2.5 years) and 10 younger (24.4 ± 4.0 years) physically active volunteers participated. Physical activity was measured with accelerometry. Leg muscle mass was quantified with dual X-ray absorptiometry. The CP and maximum power during a graded exercise test (P ) of single-leg knee-extension exercise were determined over the course of four visits. During a fifth visit, vascular function of the leg was assessed with passive leg movement (PLM) hyperaemia and leg blood flow and vascular conductance during knee-extension exercise at 10 W, 20 W, slightly below CP (90% CP) and P . Despite not differing in leg lean mass (P = 0.901) and physical activity (e.g., steps per day, P = 0.735), older subjects had ∼30% lower mass-specific CP (old = 3.20 ± 0.94 W kg vs. young = 4.60 ± 0.87 W kg ; P < 0.001). The PLM-induced hyperaemia and leg blood flow and/or conductance were blunted in the old at 20 W, 90% CP and P (P < 0.05). When normalized for leg muscle mass, CP was strongly correlated with PLM-induced hyperaemia (R = 0.52; P < 0.001) and vascular conductance during knee-extension exercise at 20 W (R = 0.34; P = 0.014) and 90% CP (R = 0.39; P = 0.004). In conclusion, the age-related decline in CP is not only an issue of muscle quantity, but also of impaired muscle quality that corresponds to impaired vascular function.
衰老是导致运动耐力下降的原因，其表现为临界功率（CP）降低。我们研究了 CP 的年龄相关性下降是否独立于肌肉质量的变化，以及它是否与血管功能受损有关。10 名年龄较大的（63.1±2.5 岁）和 10 名年龄较小的（24.4±4.0 岁）身体活跃的志愿者参加了研究。通过加速度计测量身体活动。使用双能 X 线吸收法定量腿部肌肉质量。在四次就诊过程中确定了单腿膝关节伸展运动分级运动试验（P ）的 CP 和最大功率。在第五次就诊时，通过被动腿部运动（PLM）充血以及膝关节伸展运动时腿部血流量和血管传导率在 10 W、20 W、略低于 CP（90%CP）和 P 评估腿部血管功能。尽管腿部瘦体重（P=0.901）和身体活动（例如，每天步数，P=0.735）没有差异，但老年组的质量特异性 CP 降低了约 30%（旧=3.20±0.94 W·kg vs. 年轻=4.60±0.87 W·kg；P<0.001）。在 20 W、90%CP 和 P 时，PLM 诱导的充血以及腿部血流量和/或传导率在老年组中减弱（P<0.05）。当按腿部肌肉质量归一化时，CP 与 PLM 诱导的充血（R=0.52；P<0.001）和膝关节伸展运动时的血管传导率密切相关20 W（R=0.34；P=0.014）和 90%CP（R=0.39；P=0.004）。总之，CP 的年龄相关性下降不仅是肌肉数量的问题，而且是肌肉质量的下降，这与血管功能受损相对应。
