Hydration and human cardiovascular function
People undertaking prolonged vigorous exercise in the heat experience substantial bodily fluid losses due to sweating, a process termed dehydration. If these fluid losses are not replaced, endurance exercise performance may be impaired in association with significant alterations in physiological function, including marked cardiovascular strain. One of the major features of the cardiovascular strain induced by dehydration during prolonged running or cycling in the heat is the significant reductions in the amount of blood the heart pumps per beat (i.e., stroke volume) and per minute (i.e., cardiac output) and the concomitant lowering in peripheral tissue blood flow. How those responses are brought about is not as yet well understood. This project will investigate the cardiac and peripheral mechanisms underlying the reductions in stroke volume and cardiac output with dehydration during prolonged exercise in the heat.
The findings of this study will advance our understanding of human cardiovascular control during exercise and will inform how athletes could improve endurance exercise performance on the road to the Tokyo 2020 Olympic and Paralympic Games.
Watanabe K, Stöhr EJ, Akiyama K, Watanabe S, González-Alonso J. Dehydration reduces stroke volume and cardiac output during exercise because of impaired cardiac filling and venous return, not left ventricular function. Physiol Rep. 2020;8:e14433.
González-Alonso J. New ideas about hydration and its impact on the athlete’s brain, heart and muscles. Sports Sci Exch Vol 29, No 196, 1-7.
Trangmar SJ, González-Alonso J (2019). Heat, hydration and the human brain, heart and skeletal muscles. Sports Med 49 (Suppl 1):S69–S85.
Chiesa ST, Trangmar SJ, Watanabe K & González-Alonso J (2019). Integrative human cardiovascular responses to hyperthermia. In: J.D. Périard JD & Racinais S (eds.) Heat Stress in Sport and Exercise. Springer, Cham
Trangmar SJ, Chiesa ST, Llodio I, Garcia B, Kalsi K, Secher NH & González-Alonso J (2015). Dehydration accelerates reductions in cerebral blood flow during prolonged exercise in the heat without compromising brain metabolism. Am J Physiol Heart Circ Physiol 309, H1598-H1607.
Trangmar SJ, Chiesa ST, Stock CG, Kalsi KK, Secher NH & González-Alonso J (2014). Dehydration affects cerebral blood flow but not its metabolic rate for oxygen during maximal exercise in trained humans, J Physiol 592, 3143-3160.
Pearson J, Kalsi KK, Stöhr EJ, Low DA, Barker H, Ali L, González-Alonso J (2013). Haemodynamic responses to dehydration in the resting and exercising human leg. Eur J Appl Physiol 113, 1499-1509.
Stöhr EJ, González-Alonso J, Pearson J, Low DA, Ali L, Barker H & Shave R (2011). Deyhdration reduces left ventricular filling at rest and during exercise independent of twist mechanics. J Appl Physiol 111, 891-897.
Pearson J, Low DA, Stöhr E, Kalsi K, Ali L, Barker H & González-Alonso J (2011). Hemodynamic responses to heat stress in the resting and exercising human leg: insight into the effect of temperature on the skeletal muscle blood flow. Am J Physiol Regul Integr Comp Physiol 300, R663-673.
Stöhr EJ, González-Alonso J, Pearson J, Low DA, Ali L, Barker H & Shave R (2011). Effects of graded heat stress on global left ventricular function and twist mechanics at rest and during exercise in healthy humans. Exp Physiol 96, 114-124.