Arterial blood pressure and forearm vascular conductance responses to sustained and rhythmic isometric exercise and arterial occlusion in trained rock climbers and untrained sedentary subjects.
Cardiovascular responses to sustained and rhythmic (5 s on, 2 s off) forearm isometric exercise to fatigue at 40% maximal voluntary contraction (MVC) and to a period of arterial occlusion were investigated in elite rock climbers (CLIMB) as a trained population compared to non-climbing sedentary subjects (SED). Blood pressure (BP), monitored continuously by Finapres, and forearm blood flow, by venous occlusion plethysmography, were measured and used to calculate vascular conductance. During sustained exercise, times to fatigue were not different between CLIMB and SED. However, peak increases in systolic (S) BP were significantly lower in CLIMB [25 (13) mmHg; (3.3 (1.7) kPa] than in SED [48 (17) mmHg; (6.4 (2.3) kPa] (P < 0.05), with a similar trend for increases in diastolic (D) BP. Immediately after sustained exercise, forearm conductance was higher in CLIMB than SED (P < 0.05) for up to 2 min. During rhythmic exercise, times to fatigue were two fold longer in CLIMB than SED [853 (76) vs 420 (69) s, P < 0.05]. Increases in SBP were not different between groups except during the last quarter of exercise when they fell in CLIMB. Conductance both during and after rhythmic exercise was higher in CLIMB than in SED. Following a 10-min arterial occlusion, peak vascular conductance was significantly greater in CLIMB than SED [0.597 (0.084) vs 0.431 (0.035) ml x min(-1) x 100 ml(-1) x mmHg(-1); P < 0.05]. The attenuated BP response to sustained isometric exercise could be due in part to enhanced forearm vasodilatory capacity, which also supports greater endurance during rhythmic exercise by permitting greater functional hyperaemia in between contraction phases. Such adaptations would all facilitate the ability of rock climbers to perform their task of making repetitive sustained contractions.
Ferguson
R A
RA
School of Sport and Exercise Sciences, University of Birmingham, Edgbaston, UK.
Brown
M D
MD
D000222:Adaptation, Physiological / Q000502:physiology; D000328:Adult; D001794:Blood Pressure / Q000502:physiology*; D005542:Forearm / Q000098:blood supply* / Q000502:physiology; D018737:Hand Strength; D006801:Humans; D006940:Hyperemia / Q000503:physiopathology; D007537:Isometric Contraction / Q000502:physiology*; D008019:Life Style; D008297:Male; D009051:Mountaineering / Q000502:physiology*; D018763:Muscle Fatigue / Q000502:physiology; D018482:Muscle, Skeletal / Q000098:blood supply / Q000502:physiology; D010807:Physical Endurance / Q000502:physiology; D012039:Regional Blood Flow; D013564:Sympathetic Nervous System / Q000502:physiology