Neuromuscular responses in male and female athletes to two successive strength training sessions in one day.

Acute neuromuscular responses to two successive strength training sessions performed in the same day were investigated in nine male (MSA) and ten female (FSA) strength athletes. The loads for the leg extensor muscles varied between 70 and 80% of one repetition maximum (IRM) during the morning session (I) (from 10.00 to 11.00 hours) and between 70 and 100% of IRM during the afternoon session (II) (from 16.00 to 17.00 hours). Significant decreases occurred in maximal isometric strength both in MSA from 3855 +/- 791 to 3744 +/- 882 N (p < 0.05) and in FSA from 2493 +/- 553 to 2371 +/- 523 N (p < 0.05) during session I, while only slight (ns) changes took place in the maximal neural activation (IEMG) of the exercised muscles. During session II a great decrease of 8.5 +/- 6.3% (p < 0.01) took place in maximal strength (from 3911 +/- 786 to 3556 +/- 590 N) accompanied by a shift (worsening) in the average force-time curve in MSA, while only a slight change of 2.7 +/- 6.5% (ns) occurred in maximal strength (from 2462 +/- 529 to 2398 +/- 453 N) in FSA. The individual changes in the maximum averaged IEMG of the exercised muscle during session II were correlated (p < 0.05) to the individual changes in maximal strength. The present results suggest that high but submaximal loading of the neuromuscular system may result in an acute decrease in maximal strength of the exercised muscles taking place rather similarly both in males and females.(ABSTRACT TRUNCATED AT 250 WORDS)