caa a22 4500 469054476 CHVBK 20180323132839.0 cr unu---uuuuu 170328e19920701xx s 000 0 eng 10.1007/BF00868135 doi (NATIONALLICENCE)springer-10.1007/BF00868135 Cardiovascular reflexes during sustained handgrip exercise: role of muscle fibre composition, potassium and lactate [Elektronische Daten] [T. Sadamoto, Y. Mutoh, M. Miyashita] Summary: Six healthy men performed sustained static handgrip exercise for 2 min at 40% maximal voluntary contraction followed by a 6-min recovery period. Heart rate (f c), arterial blood pressures, and forearm blood flow were measured during rest, exercise, and recovery. Potassium ([K+]) and lactate concentrations in blood from a deep forearm vein were analysed at rest and during recovery. Mean arterial pressure (MAP) andf c declined immediately after exercise and had returned to control levels about 2 min into recovery. The time course of the changes in MAP observed during recovery closely paralleled the changes in [K+] (r=0.800,P<0.01), whereas the lactate concentration remained elevated throughout the recovery period. The close relationship between MAP and [K+] was also confirmed by experiments in which a 3-min arterial occlusion period was applied during recovery to the exercised arm by an upper arm cuff. The arterial occlusion affected MAP whilef c recovered at almost the same rate as in the control experiment. Muscle biopsies were taken from the brachioradialis muscle and analysed for fibre composition and capillary supply. The MAP at the end of static contraction and the [K+] appearing in the effluent blood immediately after contraction were positively correlated to the relative content of fast twitch (% FT) fibres (r=0.886 for MAP vs %FT fibres,P<0.05 andr=0.878 for [K+] vs %FT fibres,P<0.05). Capillary to fibre ratio showed an inverse correlation to % FT fibres (r=−0.979,P<0.01). These results indicated that activation of FT rather than slow twitch fibres during static contraction induced a more marked arterial pressure reflex. It was concluded that the arterial pressure reflex would seem to be mediated through stimulation of unmyelinized free nerve endings in the contracted muscle. The [K+] would appear to be a more likely candidate than lactate as a mediator for this pressure reflex. Springer-Verlag, 1992 Static contraction nationallicence Pressure reflex nationallicence Potassium concentration nationallicence Lactate concentration nationallicence Muscle fibre composition nationallicence Sadamoto T. Laboratory of Exercise Physiology and Biomechanics, Faculty of Education, University of Tokyo, Hongo 7-3-1, Bunkyoku, Tokyo, Japan aut Mutoh Y. Laboratory of Exercise Physiology and Biomechanics, Faculty of Education, University of Tokyo, Hongo 7-3-1, Bunkyoku, Tokyo, Japan aut Miyashita M. Laboratory of Exercise Physiology and Biomechanics, Faculty of Education, University of Tokyo, Hongo 7-3-1, Bunkyoku, Tokyo, Japan aut European Journal of Applied Physiology and Occupational Physiology Springer-Verlag 65/4(1992-07-01), 324-330 0301-5548 65:4<324 1992 65 421 https://doi.org/10.1007/BF00868135 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00868135 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Sadamoto T. Laboratory of Exercise Physiology and Biomechanics, Faculty of Education, University of Tokyo, Hongo 7-3-1, Bunkyoku, Tokyo, Japan aut NATIONALLICENCE 700 1- Mutoh Y. Laboratory of Exercise Physiology and Biomechanics, Faculty of Education, University of Tokyo, Hongo 7-3-1, Bunkyoku, Tokyo, Japan aut NATIONALLICENCE 700 1- Miyashita M. Laboratory of Exercise Physiology and Biomechanics, Faculty of Education, University of Tokyo, Hongo 7-3-1, Bunkyoku, Tokyo, Japan aut NATIONALLICENCE 773 0- European Journal of Applied Physiology and Occupational Physiology Springer-Verlag 65/4(1992-07-01), 324-330 0301-5548 65:4<324 1992 65 421 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer