caa a22 4500 469054328 CHVBK 20180323132839.0 cr unu---uuuuu 170328e19920501xx s 000 0 eng 10.1007/BF00705084 doi (NATIONALLICENCE)springer-10.1007/BF00705084 Effect of heat stress on muscle blood flow during dynamic handgrip exercise [Elektronische Daten] [Juhani Smolander, Veikko Louhevaara] Summary: During exercise in a hot environment, blood flow in the exercising muscles may be reduced in favour of the cutaneous circulation. The aim of our study was to examine whether an acute heat exposure (65-70°C) in sauna conditions reduces the blood flow in forearm muscles during handgrip exercise in comparison to tests at thermoneutrality (25° C). Nine healthy men performed dynamic handgrip exercise of the right hand by rhythmically squeezing a water-filled rubber tube at 13% (light), and at 34% (moderate) of maximal voluntary contraction. The left arm served as a control. The muscle blood flow was estimated as the difference in plethysmographic blood flow between the exercising and the control forearm. Skin blood flow was estimated by laser Doppler flowmetry in both forearms. Oesophageal temperature averaged 36.92 (SEM 0.08) ° C at thermo-neutrality, and 37.74 (SEM 0.07) ° C (P<0.01) at the end of the heat stress. The corresponding values for heart rate were 58 (SEM 2) and 99 (SEM 5) beats -min−1 (P<0.01), respectively. At 25° C, handgrip exercise increased blood flow in the exercising forearm above the control forarm by 6.0 (SEM 0.8) ml · 100 ml−1 · min−1 during light exercise, and by 17.9 (SEM 2.5) ml · 100 ml−1 · min−1 during moderate exercise. In the heat, the increases were significantly higher: 12.5 (SEM 2:2) ml · 100 ml−1 · min−1 at the light exercise level (P<0.01), and 32.2 (SEM 5.9) ml · 100 ml−1·min−1 (P<0.05) at the moderate exercise level. Skin blood flow was not significantly different in any of the test conditions between the two forearms. These results suggested that hyperthermia of the observed magnitude did not reduce blood flow in active muscles during light or moderate levels of dynamic handgrip exercise. Springer-Verlag, 1992 Heat stress nationallicence Muscle blood flow nationallicence Cutaneous circulation nationallicence Plethysmography nationallicence Laser Doppler nationallicence Smolander Juhani Department of Physiology, Institute of Occupational Health, Laajaniityntie 1, SF-01620, Vantaa, Finland aut Louhevaara Veikko Department of Physiology, Institute of Occupational Health, Laajaniityntie 1, SF-01620, Vantaa, Finland aut European Journal of Applied Physiology and Occupational Physiology Springer-Verlag 65/3(1992-05-01), 215-220 0301-5548 65:3<215 1992 65 421 https://doi.org/10.1007/BF00705084 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00705084 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Smolander Juhani Department of Physiology, Institute of Occupational Health, Laajaniityntie 1, SF-01620, Vantaa, Finland aut NATIONALLICENCE 700 1- Louhevaara Veikko Department of Physiology, Institute of Occupational Health, Laajaniityntie 1, SF-01620, Vantaa, Finland aut NATIONALLICENCE 773 0- European Journal of Applied Physiology and Occupational Physiology Springer-Verlag 65/3(1992-05-01), 215-220 0301-5548 65:3<215 1992 65 421 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer