Effect of carbohydrate-protein supplement timing on acute exercise-induced muscle damage

Abstract

Purpose: To determine if timing of a supplement would have an effect on muscle damage, function and soreness.

Methods: Twenty-seven untrained men (21 +/- 3 yrs) were given a supplement before or after exercise. Subjects were randomly assigned to a pre exercise (n = 9), received carbohydrate/protein drink before exercise and placebo after, a post exercise (n = 9), received placebo before exercise and carbohydrate/protein drink after, or a control group (n = 9), received placebo before and after exercise. Subjects performed 50 eccentric quadriceps contractions on an isokinetic dynamometer. Tests for creatine kinase (CK), maximal voluntary contraction (MVC) and muscle soreness were recorded before exercise and at six, 24, 48, 72, and 96 h post exercise. Repeated measures ANOVA were used to analyze data.

Results: There were no group by time interactions however, CK significantly increased for all groups when compared to pre exercise (101 +/- 43 U/L) reaching a peak at 48 h (661 +/- 1178 U/L). MVC was significantly reduced at 24 h by 31.4 +/- 14.0%. Muscle soreness was also significantly increased from pre exercise peaking at 48 h.

Conclusion: Eccentric exercise caused significant muscle damage, loss of strength, and soreness; however timing of ingestion of carbohydrate/protein supplement had no effect.

Figure 1

Peak torque of maximal voluntary contraction (MVC) across the 96 hours. Values are means ± standard errors, * p < 0.05, significantly different from 0 time point, there were no differences among groups. Pre, received supplement before exercise and placebo after; Post, received supplement after exercise and placebo before exercise; Control, received placebo before and after exercise.

Figure 2

Percent decrease of maximal voluntary contraction (MVC) across the 96 hours. Values are means ± standard errors. Values for % decrease in MVC = ((Pre – time point)/Pre) × 100. * p < 0.05, significantly different from 0 time point, there were no differences among groups. Pre, received supplement before exercise and placebo after; Post, received supplement after exercise and placebo before exercise; Control, received placebo before and after exercise.

Figure 3

Serum creatine kinase (CK) Concentration across the 96 hours. Values are means ± standard errors. * p < 0.05, significantly different from 0 time point, there were no differences among groups. Pre, received supplement before exercise and placebo after; Post, received supplement after exercise and placebo before exercise; Control, received placebo before and after exercise.

Figure 4

Visual analogue scale (VAS) across the 96 hours. Values are means ± standard errors. * p < 0.05, significantly different from 0 time point, there were no differences among groups. Pre, received supplement before exercise and placebo after; Post, received supplement after exercise and placebo before exercise; Control, received placebo before and after exercise