Effect of a hamstring flexibility program performed concurrently during an elite canoeist competition season.

The aim of this study was to determine de acute effect of an 8-weeks specific hamstring flexibility training on junior canoeist during the competition season. Sixteen canoeists participated, divided into 3 groups: 5 in Experimental Group 1 (EG1), 5 in Experimental Group 2 (EG2) and 6 in a Control Group (CG). The EG1 underwent a supervised program consisted by Simple Static Stretching, Dynamic Static Stretching and P.N.F. while the EG2 performed a program without P.N.F. and no supervision. Two measurements were performed to analyze the effect on the knee joint ROM and trunk flexion; neuromuscular and contractile properties in Biceps Femoris (BF) and Semitendinosus (ST) muscles; maximum power and average speed in lower limbs. A mixed-design factorial analysis of variance (p <0.05) was performed and the effect size was calculated. The results show significant improvements (p <0.05) in both legs for knee joint ROM and trunk flexion in EG1 (8.9% and 25.5%; 5.7% and 20.9% in right and left leg respectively) and EG2 (6.7% and 22%; 3.9% and 24.4%), only EG1 improved muscular stiffness in BF (27.4% left leg) and ST (20.5% and 24.3%), and lateral symmetry in BF (49%) without decreasing average speed in lower limbs. All improvements have a large effect size. In conclusion, it is suggested that a supervised hamstring flexibility program performed concurrently during a canoeist competition season can produce an increase in the knee joint ROM and trunk flexion, without negative repercussions in contractile and neuromuscular capacities, maximum power and average velocity in lower limbs.