Neurovascular research laboratory, School of Kinesiology, Western University, London, Ontario, Canada.
Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, USA.
J Physiol. 2023 Jul;601(14):2877-2898. doi: 10.1113/JP284517. Epub 2023 May 5.
The impact of age on exercise pressor responses is equivocal, likely because of sex-specific neuro-cardiovascular changes with age. However, assessments of the interactive effects of age and sex on muscle sympathetic nerve activity (MSNA) responses to exercise are lacking. We tested the hypothesis that older females would exhibit exaggerated increases in blood pressure (BP) and MSNA discharge patterns during handgrip exercise compared with similarly aged males and young adults. Twenty-five young (25 (2) years; mean (SD)) males (YM; n = 12) and females (YF; n = 13) and 23 older (71 (5) years) males (OM; n = 11) and females (OF; n = 12) underwent assessments of BP, total peripheral resistance (TPR; Modelflow) and MSNA action potential (AP) discharge patterns (microneurography) during incremental rhythmic handgrip exercise and post-exercise circulatory occlusion (PECO). OM demonstrated larger ∆BP and ∆TPR from baseline than YM (both P < 0.001) despite smaller increases in ∆APs/burst (OM: 0.4 (3) vs. YM: 5 (3) spikes/burst, P < 0.001) and ∆AP clusters/burst (OM: 0.1 (1) vs. YM: 1.8 (1) clusters/burst, P < 0.001) during exercise. Testosterone was lower in OM than YM (P < 0.001) and was inversely related to ∆BP but positively related to ∆AP clusters/burst in males (both P = 0.03). Conversely, YF and OF demonstrated similar ∆BP and ∆AP discharge during exercise (range: P = 0.75-0.96). Age and sex did not impact haemodynamics or AP discharge during PECO (range: P = 0.08-0.94). Altogether, age-related changes in neuro-cardiovascular reactivity exist in males but not females during fatiguing exercise and seem to be related to testosterone. This sex-specific impact of age underscores the importance of considering biological sex when assessing age-related changes in neuro-cardiovascular control during exercise. KEY POINTS: Older males have the largest increase in blood pressure despite having the smallest increases in sympathetic vasomotor outflow during rhythmic handgrip exercise. Young males demonstrate greater increases in sympathetic action potential (AP) discharge compared with young females during rhythmic handgrip exercise. Older adults (regardless of sex) demonstrate smaller increases in muscle sympathetic nerve activity (MSNA) burst amplitude and total AP clusters compared with young adults during exercise, as well as smaller increases in integrated MSNA burst frequency, incidence and total MSNA activity during post-exercise circulatory occlusion (i.e. independent effect of age). Males, but not females (regardless of age), reflexively modify AP conduction velocity during exercise. Our results indicate that age and sex independently and interactively impact the neural and cardiovascular homeostatic adjustments to fatiguing small muscle mass exercise.
年龄对运动升压反应的影响尚无定论，这可能是由于性别特异性的神经心血管变化随年龄而变化。然而，关于年龄和性别对运动时肌肉交感神经活动（MSNA）反应的交互影响的评估还很缺乏。我们假设与同龄男性和年轻成年人相比，老年女性在握力运动期间会表现出血压（BP）和 MSNA 放电模式的过度增加。25 名年轻男性（25（2）岁；平均值（SD））（YM；n=12）和女性（YF；n=13）和 23 名老年男性（71（5）岁）（OM；n=11）和女性（OF；n=12）接受了血压、总外周阻力（TPR；Modelflow）和 MSNA 动作电位（AP）放电模式（微神经记录）的评估，在递增节奏性握力运动和运动后循环闭塞（PECO）期间。与 YM 相比，OM 从基线时的 BP 和 TPR 增加更大（均 P < 0.001），尽管 ∆APs/爆发（OM：0.4（3）比 YM：5（3）峰/爆发，P < 0.001）和 ∆AP 簇/爆发（OM：0.1（1）比 YM：1.8（1）簇/爆发，P < 0.001）的增加较小。OM 中的睾丸激素低于 YM（P < 0.001），并且与男性的 BP 呈负相关，但与 ∆AP 簇/爆发呈正相关（均 P=0.03）。相反，YF 和 OF 在运动期间表现出相似的 BP 和 AP 放电（范围：P=0.75-0.96）。年龄和性别在 PECO 期间对血液动力学或 AP 放电没有影响（范围：P=0.08-0.94）。总之，在疲劳运动期间，男性存在与年龄相关的神经心血管反应变化，但女性没有，这似乎与睾丸激素有关。这种年龄的性别特异性影响强调了在评估运动期间神经心血管控制的与年龄相关的变化时，考虑生物学性别很重要。关键点：与年轻女性相比，老年男性在进行节奏性握力运动时，血压升高幅度最大，尽管交感血管输出的增加幅度最小。与年轻女性相比，年轻男性在进行节奏性握力运动时表现出更大的交感神经动作电位（AP）放电增加。与年轻成年人相比，老年成年人（无论性别如何）在运动期间表现出 MSNA 爆发幅度和总 AP 簇的增加较小，以及运动后循环闭塞期间（即年龄的独立影响）的综合 MSNA 爆发频率、发生率和总 MSNA 活动的增加较小。男性（无论女性年龄如何）在运动期间会反射性地改变 AP 传导速度。我们的结果表明，年龄和性别独立且相互作用地影响神经和心血管对疲劳性小肌肉质量运动的稳态调节。
