STRENGTH RECOVERY IS INFLUENCED BY THE WARM-UP EFFECT

Green, L., Parro, J., & Gabriel, D. A. (2013). Recovery of strength following local muscular fatigue in the tibialis anterior. Medicine & Science in Sports & Exercise, 45(5), Supplement abstract number 461.

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This study examined the recovery in strength following local muscular fatigue in the tibialis anterior muscle in males (N = 14). On two separate test sessions, Ss performed repeated maximal isometric dorsiflexion contractions until a 10 or 20% force decrement had been achieved. Recovery was assessed with 3-second maximal voluntary contractions at minutes 1, 3, 6, 10, and 15 following the fatigue protocol. Force and surface electromyography (sEMG) were recorded concurrently.

Force decreased from ~237.1 N to ~202.8 N and returned to 100.5% in the 10% condition. There was a decrease from ~227.9 N to ~183.1 N in the 20% condition which returned to 99.5% of the Ssí initial force levels. The full recovery in force after 15 minutes (which is seldom seen) was attributed to a warm-up effect as indicated by stereotypical changes associated with an increase in muscle temperature. The mean power frequency of the sEMG signal was found to over-recover which is consistent with increased muscle fiber conduction velocity caused by the warm-up effect. Lastly, a decreased level of antagonist (soleus) muscle activity (9%) relative to the agonist was seen during recovery. This decrease in antagonist co-activation suggests that there was a reduction in the amount of opposing force. Thus, alterations in neuromotor coordination may have had some contribution to the timely recovery of force.

Implication. The warm-up theory is able to explain all the changes in the sEMG during the recovery period, as well as the increase in maximal force. It appears that force recovery was not dependent on the depth of fatigue.

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