Impact of Effective Frequency Jack-knife Stretching on Preadolescent Male Football Players -Prospective Cohort Study-

Abstract

Objective: We aimed to investigate the effective frequency of jack-knife stretching in preadolescent male football players. Methods: We enrolled 47 male preadolescent football players (average age: 12.4 ± 0.6 years old). All participants took surveys at baseline and after intervention for 6 months. The survey items were height, weight, body mass index, anteflexion in sitting, and quadriceps and hamstring tightness. The participants were divided into two groups according to the stretching exercise frequency, where group A performed stretching at least once every 3 days and group B performed stretching less than once every 3 days. After exclusion, 17 participants were enrolled in each group.Results: There was a significant increase in anteflexion in the sitting position in group A but not group B; moreover, straight leg raising was significantly larger in Group AConclusions: Performing jack-knife stretching at least once every 3 days’ intervals could improve hamstring flexibility in preadolescent male football players.Level of Evidence Level Ⅱ

Comparison of Jack Knife Stretching and Miofacial Decompression on Increasing Hamstring Muscle Flexibility in Futsal Players

“…According to Nakase et al (2021), doing jack knife stretching at least once a day for 3 days can increase hamstring muscle flexibility in pre-teen male soccer players. Jack Knife Stretching done twice a day can increase hamstring flexibility (Nakase et al, 2021).…”