Trangmar Steven J, González-Alonso José
Carnegie School of Sport, Leeds Beckett University, Leeds, UK.
Department of Sport, Health and Exercise Sciences, College of Health, Medicine and Life Sciences, Brunel University of London, Uxbridge, UK.
Exp Physiol. 2025 Jun 18. doi: 10.1113/EP092742.
Blood flow in the inactive limb tissues and skin is widely thought to decline during incremental exercise to exhaustion due to augmented sympathoadrenal vasoconstrictor activity, but direct evidence to support this view is lacking. Here, we investigated the inactive-forearm haemodynamic ( ) and oxygenation responses to a range of two-leg exercise intensities and durations in the heat. Blood oxygen and flow were measured in the forearm tissue and skin of endurance-trained males during three incremental cycling exercise tests, with tests 1 and 2 separated by a 2 h bout of moderate constant load cycling exercise, all performed in the heat (35°C, 50% relative humidity, with fan cooling). In incremental exercise tests 1 and 3, was stable from rest to ∼40% W, before increasing by ∼118% at 80% W (P <0.001). Correspondingly, forearm skin arterio-venous oxygen difference (a-vO diff) decreased by ∼62% at 80% W (P = 0.043), remaining reduced through to W. Concomitantly, forearm skin blood flow more than doubled, while forearm deep tissue O saturation decreased. When incremental exercise started shortly after constant load exercise (test 2), was 2- to 3-fold higher than during tests 1 and 3, whereas skin a-vO diff was suppressed to a low level. Similar changes were observed during constant load exercise. In conclusion, skin perfusion increases during incremental exercise in the heat, concomitant to proportional reductions in oxygen extraction from the cutaneous circulation. Hence, contrary to the generally held view, skin perfusion remains elevated during maximal exercise and heat stress despite profound increases in sympathoadrenal activity.
人们普遍认为，在递增运动直至力竭的过程中，由于交感肾上腺血管收缩活动增强，非活动肢体组织和皮肤的血流量会下降，但缺乏支持这一观点的直接证据。在此，我们研究了在热环境中，非活动前臂对一系列双腿运动强度和持续时间的血流动力学及氧合反应。在三项递增式自行车运动测试中，对耐力训练男性的前臂组织和皮肤进行了血氧和血流测量，测试1和测试2之间间隔了2小时的中等强度恒定负荷自行车运动，所有测试均在热环境（35°C，相对湿度50%，有风扇冷却）中进行。在递增运动测试1和3中，[具体指标]从静息状态到约40%最大摄氧量（W）时保持稳定，在80%W时增加约118%（P<0.001）。相应地，前臂皮肤动静脉氧差（a-vO₂ diff）在80%W时下降约62%（P = 0.043），直至最大摄氧量（W）时仍保持降低。与此同时，前臂皮肤血流量增加了一倍多，而前臂深部组织氧饱和度下降。当在恒定负荷运动后不久开始递增运动（测试2）时，[具体指标]比测试1和3时高2至3倍，而皮肤a-vO₂ diff被抑制到较低水平。在恒定负荷运动期间也观察到了类似变化。总之，在热环境中进行递增运动时，皮肤灌注增加，同时皮肤循环中氧摄取量相应减少。因此，与普遍观点相反，尽管交感肾上腺活动显著增加，但在最大运动和热应激期间，皮肤灌注仍保持升高。
