Effects of acute aerobic and concurrent exercise on skeletal muscle metabolic enzymes in untrained men

Abstract

Background

Acute exercise can increase skeletal muscle citrate synthase (CS) enzyme activity and resting skeletal muscle mitochondrial enzyme activity has been linked to maximal oxygen consumption ($\dot {V}{{\text{O}}_{2\hbox{max} }}$). We investigated: (1) if acute aerobic exercise (AEx) increases muscle metabolic enzyme activities other than CS; (2) if the addition of acute resistance exercise (REx) enhances the response to AEx (A + REx); and (3) if post-exercise muscle metabolic enzyme activity was related to $\dot {V}{{\text{O}}_{2\hbox{max} }}$.

Methods

Twelve young, sedentary men completed 45 min of two-legged cycle ergometry at 55% of $\dot {V}{{\text{O}}_{2\hbox{max} }}$ and 3 sets of 8–12 repetitions of one-leg knee extensor at 55% of 1 repetition maximum (1-RM). Vastus lateralis biopsies were taken prior to and 1 h post AEx and A + REx for the measurement of phosphofructokinase (PFK), 3-l-hydroxyacyl CoA dehydrogenase (β-HAD), succinate dehydrogenase (SDH) and CS.

Results

As a group, there was no effect of acute AEx or A + REx on muscle PFK, β-HAD, CS, and SDH activities. Post exercise muscle PFK, β-HAD, CS, and SDH activities were related to higher $\dot {V}{{\text{O}}_{2\hbox{max} }}$ (r = 0.62–0.74). With participants grouped by $\dot {V}{{\text{O}}_{2\hbox{max} }}$ (LOW, < 30th %; NORM, > 50th %), acute exercise-induced changes in muscle PFK, β-HAD, CS, and SDH were greater in NORM compared to LOW.

Conclusion

These findings suggest acute exercise muscle metabolic enzyme activities are predictive of $\dot {V}{{\text{O}}_{2\hbox{max} }}$ and possibly supportive of higher $\dot {V}{{\text{O}}_{2\hbox{max} }}$. Also, low $\dot {V}{{\text{O}}_{2\hbox{max} }}$ (below 30th percentile) appears to impair skeletal muscle metabolic enzyme responses to acute exercise.