Acute stretch perception alteration contributes to the success of the PNF "contract-relax" stretch.

CONTEXT: Some researchers have suggested that an alteration of stretch perception could be responsible for the success of the contract-relax (CR) stretch, a stretch technique derived from proprioceptive neuromuscular facilitation (PNF). OBJECTIVE: This study was conducted to determine if the alteration of the stretch perception is a possible explanation for the range of motion (ROM) gains of the CR stretch. PARTICIPANTS: Eighteen subjects performed two stretches in randomized order: the slow stretch and the CR stretch. MAIN OUTCOME MEASURE: The stretch intensity was controlled. The stretch force was measured and compared between the slow stretch and CR stretch. RESULTS: There was a significant difference between the stretch force that could be applied in the PNF stretch (126.0 N) and the slow stretch (108.4 N); P = 0.00086. The average stretch tolerance progressively increased with successive trials from 120.6 N in the first trial to 132.4 N in the fourth trial. CONCLUSION: The alteration of stretch perception plays a role in the success of the CR form of PNF stretching. At least four repetitions of the CR stretch are recommended to get the greatest ROM gain.