Saturday, January 26, 2008

Recovery again

I recently posted about a study comparing active and passive recovery in football players. I'm still thinking about the paper and may write something more on it soon. In the meantime I wanted to record a couple of other papers that I came across about recovery or conversely under-recovery!

Firstly, one that indicates that three consecutive days of relatively moderate exercise (60% V O2peak) will lead to what I would call over-training - you get weaker, partly due to some systemic fatigue.....

Effects of consecutive days of exercise and recovery on muscle mechanical function.

Purpose: To investigate the effects of three consecutive days of prolonged exercise on muscle mechanical function, 12 volunteers (V[spacing dot above]O2peak = 44.8 +/- 2.0 mL[middle dot]kg-1[middle dot]min-1, mean +/- SE) cycled at approximately 60% V[spacing dot above]O2peak until fatigue.

Methods: Quadriceps muscle function was assessed before and after exercise on day 1 (E1) and day 3 (E3) and during three consecutive days of recovery (R1, R2, R3), using both voluntary and electrically induced contractions at various stimulation frequencies.

Results: Exercise on E1 and E3 resulted in a 40% (120 +/- 12 vs 72 +/- 10 N) and 35% (117 +/- 14 vs 78 +/- 8 N) deficit (P < 0.05) in force at 10 Hz, respectively, which remained depressed (P < 0.05) by 32-34% during R1-R3. At 100 Hz, force, although not altered by exercise at E1 or E3, was decreased (P < 0.05) by 12-16% during recovery. The maximal rate of relaxation (-dF/dtmax) at 10 Hz was reduced (P < 0.05) by 38% on E1, by 32% on E3, and remained depressed by 38% through R3. At 100 Hz, -dF/dtmax was only depressed (P < 0.05) during recovery. Maximal rate of force development (+dF/dtmax) at 10 Hz was reduced (P < 0.05) by exercise, but not in recovery. Maximal voluntary contraction force was depressed (P < 0.05) with exercise at both E1 and E3 and remained depressed (P < 0.05) throughout recovery. The reduction (P < 0.05) in motor unit activation assessed with the interpolated twitch technique, observed during recovery, suggests that part of the incomplete recovery (weakness) is central in origin.

Conclusions: These results demonstrate that three consecutive days of prolonged exercise result in a weakness that persists for at least 3 d, compromising force during both voluntary and induced contractions

Secondly - and this one is more related to the previous study about active vs passive recovery - there was this comparison between different recovery strategies. In this study, active recovery came out on top.....

Comparison of recovery strategies on muscle performance after fatiguing exercise.

OBJECTIVE: The objective of this study was to assess the influence of different relaxation modes: stretching (ST), active recovery (AR), and passive recovery (PR) on muscle relaxation after dynamic exercise of the quadriceps femoris.
DESIGN: Ten healthy male volunteers between 24 and 38 yrs of age participated in this study. After the warm-up, subjects performed three sets of dynamic leg extension and flexion (at an angle of 20-110 degrees) at 50% of previously determined maximal voluntary contraction (MVC), with 30 secs. of rest between sets. Immediately after completing the leg exercise, one of the relaxation methods was applied, in a randomized order (AR, PR, ST). Then, subjects performed isometric knee extension at 50% of MVC to the point of fatigue, and surface electromyogram (EMG) of the vastus lateralis muscle was measured.
RESULTS: After AR, the mean MVC was significantly (P <> 0.05). Total time of the effort during EMG measurement was significantly lower for all three recovery modes than at baseline. During the effort after both PR and ST, there was no significant increase in motor unit activation, but a significant increase was noted after AR (P <> 0.05).
CONCLUSION: The results of this study suggest that the most appropriate and effective recovery mode after dynamic muscle fatigue involves light, active exercises, such as cycling with minimal resistance.

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