G-Force Training Rewires How Blood Vessels Respond to Pressure
Researchers found that five weeks of high-gravity exposure fundamentally changes how tiny blood vessels in the skin regulate blood flow under pressure. The discovery could inform countermeasures for astronauts, airline pilots, and athletes—while revealing previously unknown limits of circulatory adaptation in the human body.
Originaltitel: In vivo pressure-flow relation of human cutaneous vessels following prolonged iterative exposures to hypergravity
<p>The study examined intra- and interlimb variations in cutaneous vessel responsiveness to acute and repeated transmural pressure elevations. In 11 healthy men, red blood cell flux was assessed via laser-Doppler flowmetry on both glabrous and nonglabrous skin regions of an arm (finger and forearm) and leg (toe and lower leg), across a wide range of stepwise increasingdistending pressures imposed in the vessels of each limb separately. The pressure-flux cutaneous responses were evaluatedbefore and after 5 wk of intermittent (40 min, 3 sessions per week) exposures to hypergravity (2.6–3.3 G; G training). Beforeand after G training, forearm and lower leg blood flux were relatively stable up to 210 and 240 mmHg distending pressures,respectively; and then they increased two- to threefold (P < 0.001). Finger blood flux dropped promptly (P < 0.001), regardlessof the G training (P = 0.64). At 120-mmHg distending pressures, toe blood flux enhanced by 40% (P 0.05); the increasewas augmented after the G training (P = 0.01). At high distending pressures, toe blood flux dropped by 70% in both trials (P <0.001). The present results demonstrate that circulatory autoregulation is more pronounced in glabrous skin than in nonglabrousskin, and in nonglabrous sites of the leg than in those of the arm. Repetitive high-sustained gravitoinertial stress does not modifythe pressure-flow relationship in the dependent skin vessels of the arm nor in the nonglabrous sites of the lower leg. Yet it maypartly inhibit the myogenic responsiveness of the toe’s glabrous skin.</p>