Exercise‐induced decreases in sarcoplasmic reticulum Ca²⁺–ATPase activity attenuated by high‐resistance training

Abstract

Muscle biopsies were performed on the vastus lateralis muscle prior to and during a high-resistance training (HRT) programme in order to examine the effects of hypertrophy on sarcoplasmic reticulum Ca2+ ATPase activity at rest and during exercise. In six male untrained volunteers (peak aerobic power, Vo2 peak = 3.39 +/- 0.13 L min-1, mean +/- SE), the resting Ca2+ ATPase activity (mumol-min-1 g wet wt-1) at 0 (4.89 +/- 0.20), 4 (5.62 +/- 0.56), 7 (5.15 +/- 0.41) and 12 (4.82 +/- 0.11) weeks was unchanged by HRT. During cycle ergometer exercise, prior to training, Ca(2+)-ATPase was reduced (P < 0.05) by 14% during the initial 30 min at 58% Vo2 peak and (P < 0.05) a further 19% during 30 min at 72% Vo2 peak. Following 7 and 12 weeks of training, the decreases in SR Ca(2+)-ATPase were less pronounced (P < 0.05). These results indicate that muscle hypertrophy, although incapable of altering Ca(2+)-ATPase pump activity at rest, can attenuate the decrease observed in exercise by mechanism(s) as yet unknown.

Effect of exercise on sarcoplasmic reticulum Ca&lt;sup&gt;2+&lt;/sup&gt; transport in muscle of mouse lines long-term selected for different Performance traits

“…Also, the minor differences in Ca 2+ ATPase activities at rest do not lead to the conclusion that the selection had the expected effect on SR Ca 2+ transport. This is in agreement with training experiments, showing an increased Performance but no change in Ca 2+ transport (SEMBROWICH et al, 1978;MADSEN et al, 1994;GREEN et al, 1998), but not with other investigations, indicating a reduced uptake and ATPase activity by long-term training (BELCASTRO, 1987), or an increased uptake and ATPase activity (WILSON et al, 1998), determined at rest. In agreement with the majority of investigations Ca 2+ uptake was affected by the level of exercise.…”

“…However, Sprint conditioning of horses attenuated the decrease in the calcium transfer rate and in the Ca 2+ ATPase activity (WILSON et al, 1998), and high-resistance training attenuated exercise induced decreases in SR Ca ATPase activity (GREEN et al, 1998). It is suggested that exercise training can retard the onset of fatigue by an attenuation ofa disturbance ofthe Ca 2+ transport (GREEN et al, 1998;WILSON et al, 1998). Selection is another way to influence characters of animals.…”

Adaptations in human muscle sarcoplasmic reticulum to prolonged submaximal training

“…Although the effect of voluntary exercise on Ca 2ϩ -ATPase activity remains controversial, particularly in rats (7), studies have reported reductions in muscles composed of a predominance of fast-twitch fibers (4,42), presumably as a result of inactivation of the nucleotide binding site (18). Such a mechanism also appears to exist during prolonged exercise in humans because several studies have reported disturbances in Ca 2ϩ -ATPase activity in the vastus lateralis (2,10,15). Reductions in Ca 2ϩ -ATPase activity also appear to be accompanied by reductions in Ca 2ϩ uptake (2,15).…”

Initiating treadmill training in late middle age offers modest adaptations in Ca2+handling but enhances oxidative damage in senescent rat skeletal muscle

“…With 12 wk of resistance training, Ca 2ϩ -ATPase activity and Ca 2ϩ uptake were increased in elderly women but were still lower than in young women, whereas young adult women showed no change (21). Another study showed that Ca 2ϩ -ATPase activity in resting vastus lateralis muscle was unaltered with high resistance training but showed smaller losses during exercise in young men (18). In young adult Wistar rats, high-intensity treadmill training increased the rate of Ca 2ϩ uptake in the superficial vastus lateralis muscle but had no effect on the Ca 2ϩ -ATPase activity (27).…”