![]() ![]() ![]() In young adults, whole body cold stress elicits a pronounced systemic pressor response ( 3, 4, 9, 23, 62), and this pressor response to mild cold stress (i.e., with no reduction in core body temperature) is exaggerated in aged humans ( 23, 60). Reflex cutaneous vasoconstriction is markedly attenuated in healthy older adults, likely mediated by impairments in both end-organ responsiveness ( 30, 51, 55) and the thermoregulatory control of skin sympathetic nerve activity ( 19). As such, understanding age-related changes in the acute sympathetic and pressor responses to cold stress is clinically relevant.Īcute responses to moderate cold exposure are altered in older adults ( 2, 25, 28). Perturbations that further challenge systemic physiological function during cold exposure, such as static or dynamic exercise, may result in increased sympathetic activation and excessive increases in BP, imparting even greater risk for an acute cardiovascular event in older adults. Therefore, alterations in the acute responses to cold may contribute to the clinical relation between cold temperatures and increased cardiovascular-related mortality in primary aging. The acute systemic physiological responses to cold exposure include peripheral and visceral vasoconstriction, elevated plasma norepinephrine, and increased blood pressure (BP) ( 9, 52, 62). Furthermore, cardiovascular-related morbidity and mortality increase at low ambient temperatures, especially in older adults ( 5, 38, 44, 50, 63). ![]() Furthermore, concomitant cold stress did not alter the sympathetic responses to isometric exercise in either age group, suggesting preserved sympathetic responsiveness during exercise in the cold in healthy aging.Īging is a primary risk factor for cardiovascular disease, the leading cause of death in the United States ( 18). In summary, MSNA increased during cold stress in older, but not young, adults. MSNA was greater in older adults at T sk = 34.0☌ and throughout cooling ( P 0.05) or older adults (Δ12 ± 1 T sk 34☌ vs. Blood pressure (BP Finometer) and MSNA (microneurography) were measured throughout cooling and during isometric handgrip at 30% maximal voluntary contraction performed at a mean skin temperature (T sk) of 34 and 30.5☌. Whole body cooling (water-perfused suit) was conducted in 11 young (23 ± 1 yr) and 12 healthy older adults (60 ± 2 yr). We hypothesized that cold stress would 1) increase muscle sympathetic nerve activity (MSNA) and 2) augment the MSNA response to isometric handgrip in older adults. Human aging is associated with exaggerated pressor responses to whole body cooling however, the sympathetic response to cold stress alone and in combination with isometric exercise is unknown. Cardiovascular mortality increases in cold weather in older adults, and physical activity may impart even greater cardiovascular risk than cold exposure alone. ![]()
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