Optimal number of sets to achieve maximal muscle elongation through the static stretching ! technique: an acute study

Aim: The scientific literature is often contradictory (1-3) regarding the number of sets that are suggested in work protocols using static stretching. Only Taylor et al. (4), studying the effect of SS, maintained for the duration of 30 seconds, on two muscle groups of rabbits in vivo (tibialis anterior and extensor digitorum longus), arrived at the identification of a number of four sets to obtain the maximal muscle flexibility. The aim of this research was to identify, in a group of individuals engaging in fitness activities, the optimal number of sets for the achievement of the maximal muscle elongation through the use of the SS technique with the maintenance of postures for 30 seconds. Methods: Nine female were studied (age 26±3 years, height 167±4 cm, weight 59±5 kg and number of sessions training per week equal to 3). The participants were divided into two groups (A and B) and carried out two test sessions at a distance of fifteen days according to an experimental design called the counter balance design: the first day group A carried out the test without a warm up (WO) and group B with a warm up (W), on the second day the procedure was reversed. The group was subjected to the sit and reach test to measure trunk and hamstring flexibility. The test was repeated at regular intervals of 30 seconds. The maximum static elongation achieved was maintained for 30 seconds. The test was stopped when the records did not improve on three consecutive occasions. Results: The data analysis (Wilcoxon test) showed no statistically significant differences (W vs WO) in: 1) the maximum ROM reached (ns, +2%); 2) the set number (ns, -6%), that was found to be equal to 8; statistically significant differences were revealed in the comparisons between the baseline and the maximal ROM reached both with W (p <0.05, +16%) and WO (p <0.05, +14%). Conclusion: The results obtained suggest that for the SS technique with the maintenance of the postures for 30 seconds, and a recovery of 30 seconds, 8 sets are necessary for a sample of female gym users to achieve maximum muscle flexibility regardless of warm up. References 1 Depino GM, Webright WG, Arnold BL. Duration of maintained hamstring flexibility after cessation of an acute static stretching protocol, Journal of Athletic Training 2000;35(1):56-59 2 Wydra G., Lo Stretching ed i suoi metodi, Rivista SDS CONI, Anno XX, Gennaio-Marzo 2001, (51): 39- 48 3 Roberts JM, Wilson K. Effect of stretching duration on active and passive range of motion in the lower extremity, Br J Sports Med. 1999 Aug;33(4):259-63 4 Taylor DC, Dalton JD Jr, Seaber AV, Garrett WE Jr. Viscoelastic properties of muscle-tendon units. The biomechanical effects of stretching.The American Journal of Sports Medicine,1990: 18, 300-9