Mj. Mckenna et al., EFFECTS OF TRAINING ON POTASSIUM, CALCIUM AND HYDROGEN-ION REGULATIONIN SKELETAL-MUSCLE AND BLOOD DURING EXERCISE, Acta Physiologica Scandinavica, 156(3), 1996, pp. 335-346
Ionic regulation is critical to muscle excitation. contraction and met
abolism, and thus for muscle function during exercise. This review foc
uses on the effects of training upon K+, Ca2+ and Hf ion regulation in
muscle and K+ regulation in blood during exercise. Training enhances
K+ regulation in muscle and blood and reduces muscular fatiguability.
Endurance, sprint and strength training in humans induce an increased
muscle Na+, K+ pump concentration, usually associated with a reduced r
ise in plasma [K+] during exercise. Although impaired muscle Ca2+ regu
lation plays a vital role in fatigue, little is known about possible t
raining effects. In rat fast-twitch muscle. overload-induced hypertrop
hy and endurance training were associated with reduced sarcoplasmic re
ticulum Ca2+ uptake. consistent with fast-to-slow fibre transition. In
human muscle. endurance and strength training had no effect on muscle
Ca(2+)ATPase concentration. Whilst muscle Ca2+ uptake, release and Ca
(2+)ATPase activity were depressed by fatigue. no differences were fou
nd between strength athletes and untrained individuals. Muscle H+ accu
mulation may contribute to fatigue during intense exercise and is also
modified by sprint training. Sprint training may increase muscle Lac(
-) and work output with exhaustive exercise, but the rise in muscle [H
+] is unchanged or attenuated. indicating a reduced rise in muscle [H] relative to work performed. Muscle buffering capacity can be dissoci
ated from this improved H+ regulatory capacity after training. Thus. t
raining enhances muscle and blood K+ and muscle H+ regulation during e
xercise. consistent with improved muscular performance and reduced fat
iguability: however. little is known about training effects on muscle
Ca2+ regulation during contraction.