AIM: To compare the effect of low- vs. high-volume of eccentric-biased hamstring training programs on knee-flexor strength and fascicle length changes in elite soccer players. METHODS: Nineteen elite youth soccer players took part in this study and were randomly assigned into two subgroups. For 6 weeks in-season, groups performed either a low (1 set per exercise; 10 reps in total) or a high (4 sets; 40 reps) volume eccentric training of their knee flexors. After 6 weeks (MID), players cross-overed and performed the alternate training regimen. Each training set consisted in 4 repetitions of the Nordic hamstring exercise and 6 repetitions of the bilateral stiff-leg deadlift. Eccentric knee-flexor strength (Nordbord) as well as biceps femoris long head (BFlh) and semimembranosus (SM) fascicle length (scanned with ultrasound scanner) were assessed during PRE, MID- and POST-training tests. RESULTS: Knee-flexor eccentric strength very likely increased from PRE to MID (+11.3±7.8% [low-volume] and 11.4±5.3% [high-volume]), with a possibly-to-likely increase in BFlh (+4.5±5.0% and 4.8±2.5%) and SM (+4.3±4.7% and 6.3±6.3%) fascicle length in both groups. There was no substantial changes between MID and POST. Overall, there was no clear between-group difference in the changes from PRE to MID and MID to POST for neither knee-flexor eccentric strength, BFlH nor SM fascicle length. CONCLUSION: Low-volume knee-flexor eccentric training is as effective as a greater training dose to substantially improve knee-flexor strength and fascicle length in-season in young elite soccer players. Low-volume is however likely more appropriate to be used in an elite team facing congested schedules.
AIM: To compare the effect of low- vs. high-volume of eccentric-biased hamstring training programs on knee-flexor strength and fascicle length changes in elite soccer players. METHODS: Nineteen elite youth soccer players took part in this study and were randomly assigned into two subgroups. For 6 weeks in-season, groups performed either a low (1 set per exercise; 10 reps in total) or a high (4 sets; 40 reps) volume eccentric training of their knee flexors. After 6 weeks (MID), players cross-overed and performed the alternate training regimen. Each training set consisted in 4 repetitions of the Nordic hamstring exercise and 6 repetitions of the bilateral stiff-leg deadlift. Eccentric knee-flexor strength (Nordbord) as well as biceps femoris long head (BFlh) and semimembranosus (SM) fascicle length (scanned with ultrasound scanner) were assessed during PRE, MID- and POST-training tests. RESULTS: Knee-flexor eccentric strength very likely increased from PRE to MID (+11.3±7.8% [low-volume] and 11.4±5.3% [high-volume]), with a possibly-to-likely increase in BFlh (+4.5±5.0% and 4.8±2.5%) and SM (+4.3±4.7% and 6.3±6.3%) fascicle length in both groups. There was no substantial changes between MID and POST. Overall, there was no clear between-group difference in the changes from PRE to MID and MID to POST for neither knee-flexor eccentric strength, BFlH nor SM fascicle length. CONCLUSION: Low-volume knee-flexor eccentric training is as effective as a greater training dose to substantially improve knee-flexor strength and fascicle length in-season in young elite soccer players. Low-volume is however likely more appropriate to be used in an elite team facing congested schedules.
Authors: Benjamin Drury; Sébastien Ratel; Cain C T Clark; John F T Fernandes; Jason Moran; David G Behm Journal: J Funct Morphol Kinesiol Date: 2019-11-28