Acute sympathetic vasoconstriction at rest and during dynamic exercise in cyclists and sedentary humans

Abstract

The impact of exercise training on sympathetic activation is not well understood, especially across untrained and trained limbs in athletes. Therefore, in eight sedentary subjects (maximal oxygen consumption = 40 +/- 2 ml x kg(-1) x min(-1)) and eight competitive cyclists (maximal oxygen consumption = 64 +/- 2 ml x kg(-1) x min(-1)), we evaluated heart rate, blood pressure, blood flow, vascular conductance, and vascular resistance in the leg and arm during acute sympathetic stimulation [cold pressor test (CPT)]. The CPT was also performed during dynamic leg (knee extensor) or arm (handgrip) exercise at 50% of maximal work rate (WRmax) with measurements in the exercising limb. At rest, the CPT decreased vascular conductance similarly in the leg and arm of sedentary subjects (-33 +/- 8% leg, -38 +/- 6% arm) and cyclists (-34 +/- 4% leg, -31 +/- 9% arm), and during exercise CPT-induced vasoconstriction was blunted (i.e., sympatholysis) in both the leg and arm of both groups. However, the magnitude of sympatholysis was significantly different between the arm and leg of the sedentary group (-47 +/- 11% arm, -25 +/- 8% leg), and it was less in the arm of cyclists (-28 +/- 11%) than sedentary controls. Taken together, these data provide evidence that sympathetically mediated vasoconstriction is expressed equally and globally at rest in both sedentary and trained individuals, with a differential pattern of vasoconstriction during acute exercise according to limb and exercise training status.

Maximal strength training and increased work efficiency: contribution from the trained muscle bed

“…Although potentially complicated by the small versus large muscle mass approach in these two studies, this is not the first time that arm-and leg-specific differences have been found in terms of metabolic and vascular responses (4,5,24,25,45). Recent work, investigating limb-specific regulation of blood flow during incremental arm or leg exercise, revealed that for a given local V O 2 , leg vascular conductance was five to six times greater than arm vascular conductance (4).…”

Cold Stress Effects on Exposure Tolerance and Exercise Performance

“…Gregson et al (111) observed a 30% to 40% reduction in femoral artery blood flow and conductance after immersion in 8 and 22 • C water. Wray et al (268) found that cold-water immersion of the foot also reduced femoral artery blood flow. Brachial artery blood flow is also reduced during skin-surface cooling at rest (264).…”

Exercise training improves functional sympatholysis in spontaneously hypertensive rats through a nitric oxide-dependent mechanism

“…Exercise training has been reported to increase (45,46), decrease (60), and have no effect (59) on the magnitude of functional sympatholysis in normotensive humans. Studies demonstrating training-induced enhancements in functional sympatholysis were performed in nonathlete young (45) and elderly men (46), while other studies showing either a decrease or no effect on functional sympatholysis used athletes (59) or a different study design (e.g., cross-sectional) (60). It has also been reported that short-term (2 wk) muscle immobilization (i.e., de-training) impairs functional sympatholysis in healthy young men (45).…”