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Cardiovascular and autonomic responses to stressors following 6 hours of water immersion
Author(s) -
Florian John P,
Simmons Erin E,
Chon Ki H,
Faes Luca,
Shykoff Barbara E
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.716.2
Subject(s) - cold pressor test , heart rate variability , baroreflex , heart rate , medicine , forearm , cardiology , blood pressure , vascular resistance , surgery
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, LFn HRV , and LF/HF HRV were lower, and CVR and HFn HRV 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, HFn HRV increased from baseline after WI only, and post‐WI LFn HRV 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/HF HRV , and LFn HRV 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. Support: ONR and NAVSEA DSBDP