Effect of Different Numbers of Interset Antagonist Proprioceptive Neuromuscular Facilitation Stretching on the Total Number of Repetitions for the Agonists.

Recent studies have observed that stretching applied to antagonist muscles can promote improvement in agonist muscle performance. The purpose of this study was to investigate the effect of different numbers of interset proprioceptive neuromuscular facilitation (PNF) stretching for the antagonists on the total number of repetitions completed for the agonists (quadriceps) in the leg extension exercise. Fourteen physically active individuals (age: 29.35 ± 10.5 years; body mass: 79.1 ± 11.34 kg; height: 170.4 ± 8.7 cm) participated in this study. The following experimental protocols were performed: 1) Traditional protocol (Traditional) - without previous stretching; 2) PNF with lesser duration (PNF1-3 sets of 20 secs.); 3) PNF with greater duration (PNF2-3 sets of 30 secs.). Within the experimental protocols (PNF1 and PNF2), stretching exercises for the antagonists were performed before and between the four sets of the unilateral leg extension exercise. All tests were performed on the dominant limb only. The results showed that there was a significant difference in the total number of repetitions for the PNF2 protocol versus the Traditional protocol (p = 0.026). However, there was no significant difference between the PNF1 protocol versus the Traditional protocol (p = 0.577). In conclusion, in the leg extension exercise, an extended duration of interset PNF stretching for the hamstrings, promoted greater contractile performance for the quadriceps as demonstrated by significantly greater total repetitions over four sets.