Effects of two different strength-training methods to improve adolescents’ physical soccer performance

Background: Strength training for children and adolescents was for a long time a controversial subject but is nowadays proven safe and beneficial and recommendations for children’s strength training have been put forward by scientific sports boards in several western countries. Despite that, in Sweden strength training is not very commonly applied in children and adolescent’s sport. Strength training has proven to increase the sports performance and decrease the risk of injuries both in adults and children and would therefore be a good additional training method to the sport-specific training at any age. Different types of strength training have in several studies shown to improve the jumping ability, sprint performance and several other aspects. Purpose: The aim of the present study was to investigate the differences between pre- and post-test for the physical performance test after the 8-week strength training intervention both for the whole training group together and divided by type of intervention. Method: Eighteen adolescent boys were divided in two strength training groups, a friction Flowin® training group (FTR) and a barbell training group (BTR). They were tested pre and post an eight weeks intervention for 5-10-30 m sprint, Agility zig-zag test and two different counter movement jump (CMJ) tests. Result: The 30 m sprint improved after 8 weeks intervention for both groups together (n=18) (p= 0.036). Splitting into groups based on intervention, only the BTR group improved their performance in 30 m sprint after 8 weeks intervention (p=0.036). Both the BTR and FTR decreased their performance in 5 m sprint after the 8-week intervention (BTR p=0.007, FTR p=0.014). There was no statistical significant difference between or within the groups regarding any other tests. Conclusion: Eight weeks of strength training can improve the 30m sprint performance for adolescent male soccer players after 8 weeks intervention. More research is needed to conclude whereas the increase and explosive performance for adolescents are more affected by the duration of strength training or the strength training methods. Keywords: Children, adolescent, strength training, Flowin, barbell, physical soccer performanc