The physiological responses to water immersion (WI) are known; however, the responses to stress following WI are not well-characterized. Ten healthy men were exposed to three stressors before and after completing a 6-hr resting WI: 1) 2-min cold pressor test (CP), 2) static handgrip test (HG) to fatigue at 40% of max strength followed by forearm occlusion, and 3) a 15-min 70° head-up tilt test (HUT). Heart rate (HR), blood pressure (SBP, DBP), cardiac output (Q), limb blood flow (BF), stroke volume (SV), systemic, calf, or forearm vascular resistance (SVR, CVR, FVR), baroreflex sensitivity (BRS), and frequency (low, LF; high, HF; normalized, n) domain measures of heart rate variability (HRV) were measured. CP: Post-WI HR, SBP, SV, Q, calf BF, LFnHRV, and LF/HFHRV were lower, and CVR and HFnHRV were higher, than pre-WI values (p<0.05). HG: Max strength and endurance was not affected by WI. HR, SBP, SV, Q, and calf BF were lower, and SVR and CVR were higher, than pre-WI values (p<0.05). During occlusion, HFnHRV increased from baseline after WI only, and post-WI LFnHRV was lower than pre-WI values (p<0.05). HUT: Post-WI SBP, DBP, SV, forearm BF, and BRS were lower, and HR, FVR, LF/HFHRV, and LFnHRV were higher, than pre-WI values (p<0.05). The changes suggest differential activation/depression during CP and HG (↓sympathetic/↑parasympathetic) and HUT (↑sympathetic/↓parasympathetic) following WI.
Cardiovascular and autonomic responses to stressors following 6 hours of water immersion
Faes, Luca;
2013-01-01
Abstract
The physiological responses to water immersion (WI) are known; however, the responses to stress following WI are not well-characterized. Ten healthy men were exposed to three stressors before and after completing a 6-hr resting WI: 1) 2-min cold pressor test (CP), 2) static handgrip test (HG) to fatigue at 40% of max strength followed by forearm occlusion, and 3) a 15-min 70° head-up tilt test (HUT). Heart rate (HR), blood pressure (SBP, DBP), cardiac output (Q), limb blood flow (BF), stroke volume (SV), systemic, calf, or forearm vascular resistance (SVR, CVR, FVR), baroreflex sensitivity (BRS), and frequency (low, LF; high, HF; normalized, n) domain measures of heart rate variability (HRV) were measured. CP: Post-WI HR, SBP, SV, Q, calf BF, LFnHRV, and LF/HFHRV were lower, and CVR and HFnHRV were higher, than pre-WI values (p<0.05). HG: Max strength and endurance was not affected by WI. HR, SBP, SV, Q, and calf BF were lower, and SVR and CVR were higher, than pre-WI values (p<0.05). During occlusion, HFnHRV increased from baseline after WI only, and post-WI LFnHRV was lower than pre-WI values (p<0.05). HUT: Post-WI SBP, DBP, SV, forearm BF, and BRS were lower, and HR, FVR, LF/HFHRV, and LFnHRV were higher, than pre-WI values (p<0.05). The changes suggest differential activation/depression during CP and HG (↓sympathetic/↑parasympathetic) and HUT (↑sympathetic/↓parasympathetic) following WI.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
