An interventional study of Eccentric hamstring strength training and Sprint training in Sprint Mechanical Output, Sprint Performance and Eccentric Hamstring Strength, sponsored by Comenius University. Not yet recruiting at 1 site in Slovakia. Open to male participants aged 16 Years to 17 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-10-22.
Sponsored by Comenius University · Not applicable, Interventional, and Treatment
This study will compare two different training methods used to improve sprint performance and hamstring strength in elite youth soccer players. Participants aged 16-17 years will be assigned to one of three groups: a sprint training group, an eccentric hamstring strength training group, or a control group. The two training programs will be performed for 6 weeks alongside the players' regular soccer and strength-conditioning training.
The main purpose of the study is to determine whether sprint training or eccentric hamstring strength training is more effective for improving sprint speed and sprint mechanical performance. Sprint performance will be assessed over 5, 10, 20, and 30 meters, together with mechanical variables derived from sprint force-velocity profiling. Eccentric hamstring strength will also be measured before and after the intervention.
The study will address whether a 6-week sprint training program can improve sprint performance and hamstring strength to a similar or greater extent than a targeted eccentric hamstring strength program. It is expected that sprint training will produce greater improvements in sprint-related performance, while eccentric hamstring training will produce greater improvements in eccentric hamstring strength.
This study is a three-arm, parallel-group controlled trial designed to compare the effects of sprint training and eccentric hamstring strength training in elite academy soccer players. The intervention period will last 6 weeks and will be conducted during the competitive season alongside the players' regular soccer and strength-conditioning programs. The study will include a sprint training group, an eccentric hamstring strength training group, and a matched external control group.
Following baseline testing, participants recruited from one elite soccer academy for the two experimental groups will be ranked according to their 30-m sprint time, matched according to baseline sprint performance, and then randomly allocated to either the sprint training group or the eccentric hamstring strength training group. This procedure is intended to minimize baseline differences in sprint performance between the two experimental groups. The control group will be recruited from a separate elite soccer academy and will be selected to achieve comparable baseline 30-m sprint performance to the experimental groups. The control group will not undergo random allocation. All groups will be assessed during the same competitive period and will continue their regular soccer and strength-conditioning activities throughout the study.
Before the intervention, the two experimental groups will complete a 1-week familiarization period consisting of two sessions. In the eccentric training group, familiarization will be used to establish appropriate individual loading and ensure a supramaximal eccentric stimulus. In the sprint training group, familiarization will include resisted sprint practice and individual load-velocity profiling to determine the external resistance corresponding to approximately a 50% velocity decrement.
The eccentric hamstring training program will consist primarily of two exercises: the Nordic hamstring curl and unilateral Roman chair hip extension. Both exercises will be performed with an emphasis on eccentric overload. The training volume will be intentionally kept relatively low because the intervention will be implemented during the competitive season. External resistance will be progressively increased when the prescribed repetitions can be completed without sufficient eccentric overload.
The sprint training group will perform two structured sprint sessions per week. The program will include resisted sprinting, acceleration-oriented exercises, horizontal and vertical plyometric exercises, and maximal-velocity fly sprints. Resisted sprints will be prescribed individually using approximately a 50% velocity decrement. Individual sled loads will be determined from load-velocity profiling performed during the familiarization period. The same sleds and artificial-turf surface will be used throughout the intervention to maintain consistent friction conditions.
The control group will continue its regular soccer and strength-conditioning program without the additional experimental eccentric hamstring or resisted sprint training interventions. The training schedule of the control group will be monitored to ensure that its general training exposure is comparable to that of the experimental groups as far as practically possible. All groups will participate in approximately four soccer training sessions per week, with each session lasting approximately 90 minutes.
Pre- and post-intervention testing will be performed under standardized conditions using the same testing procedures and equipment for all groups. Sprint testing will be conducted using electronic timing gates, sprint mechanical characteristics will be assessed using the 1080 Sprint system, and eccentric hamstring strength will be assessed using the NordBord system during the Nordic hamstring exercise. Participants will be instructed to avoid strenuous physical activity for at least 48 hours before testing.
Group differences over time will be analyzed using a two-way mixed-design analysis of variance, with group as the between-subject factor and time as the within-subject factor. The group × time interaction will be the primary statistical effect of interest. Bonferroni-adjusted post hoc comparisons will be used where appropriate, and effect sizes will be reported using partial eta squared and Cohen's d.
Comenius University is the lead sponsor of 42 studies on the registry; 11 are open to participants now.
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- Age 16-17 years and post-peak height velocity (post-PHV). Competing at the highest level of youth soccer in their country. Regular participation in soccer training (approximately 4 sessions per week, 90 minutes each) and competitive matches.
Successful completion of the mandatory medical examination. At least 1 year of regular physical training, including sprint or resistance training within the club.
Attendance of at least 80% of the intervention training sessions.
Exclusion Criteria:
Goalkeepers.will be automatically excluded from the study. Attendance below 80% of the intervention training sessions.
Participants assigned to the eccentric hamstring strength training group will complete a 6-week eccentric strength training program in addition to their regular soccer and strength-conditioning training. The program will consist primarily of the Nordic hamstring curl and unilateral Roman chair hip extension, performed with an emphasis on supramaximal eccentric overload and progressive external loading when required.
Other: Eccentric hamstring strength training
Participants assigned to the sprint training group will complete a 6-week structured sprint training program in addition to their regular soccer and strength-conditioning training. The program will include resisted sprints prescribed at approximately 50% velocity decrement, acceleration-oriented exercises, horizontal and vertical plyometric exercises, calf-strength exercises, and maximal-velocity fly sprints. Sprint training will be performed twice per week.
Other: Sprint training
Participants assigned to the control group will continue their regular soccer and strength-conditioning program throughout the 6-week study period without participating in the additional experimental eccentric hamstring or resisted sprint training programs. Regular soccer training will consist of approximately four 90-minute sessions per week.
Participants will complete a 6-week eccentric hamstring strength training program in addition to regular soccer and strength-conditioning training. The intervention will include the Nordic hamstring curl and unilateral Roman chair hip extension, both performed with supramaximal eccentric overload. Training will be completed once in week 1 and twice per week during weeks 2-6. Nordic hamstring curl volume will be 2 × 4 repetitions, with external load added when participants can complete all repetitions through the full range of motion. For the unilateral Roman chair hip extension, participants will perform 2 × 6 repetitions per side with external resistance held on the chest. The lowering phase will be performed eccentrically with the trained limb, while return to the starting position will be assisted by the opposite limb. Loads will be increased when needed to maintain eccentric overload. Sessions will be performed before soccer training.
Participants will complete a 6-week structured sprint training program in addition to their regular soccer and strength-conditioning training. Two sprint-focused sessions will be performed per week, separated by at least 48 hours. The first session will include horizontal plyometric exercises, acceleration-oriented drills, and resisted 15-m sprints performed with an individualized sled load corresponding to approximately a 50% velocity decrement. The second session will include calf-strength and vertical plyometric exercises, resisted sprints at approximately 50% velocity decrement, and maximal-velocity fly sprints with a 20-m run-up. Resisted sprint volume will progress throughout the intervention. Individual sled loads will be determined using load-velocity profiling during familiarization. The same sleds and artificial-turf surface will be used throughout the intervention. All sessions will be performed before regular soccer training and supervised by a physical performance coach.
Maximal Relative Theoretical Horizontal Force (F0)
Maximal relative theoretical horizontal force (F0) will be derived from the sprint force-velocity profile obtained during a 30-m sprint using the 1080 Sprint system. Participants will complete two trials, and the better value will be used for analysis.
Time frame: From baseline to the post testing at 6 weeks
Maximal Theoretical Velocity (V0)
Maximal theoretical sprint velocity (V0) will be assessed during a 30-m sprint using the 1080 Sprint motorized resistance system (1080 Motion AB, Stockholm, Sweden). Participants will complete two trials with 3 minutes of rest between trials, and the better value will be used for analysis.
Time frame: From baseline to the post testing at 6 weeks
Relative Maximal Power Output (Pmax)
Relative maximal mechanical power output (Pmax) will be derived from the sprint force-velocity profile during a 30-m sprint using the 1080 Sprint system. Participants will perform two trials separated by 3 minutes of rest, and the better value will be used for analysis.
Time frame: From baseline to the post testing at 6 weeks
Maximal Ratio of Force (RFmax)
Maximal ratio of force (RFmax) will be derived from the sprint force-velocity profile obtained during a 30-m sprint using the 1080 Sprint system. Participants will perform two trials, and the better value will be used for analysis.
Time frame: From baseline to the post testing at 6 weeks
5-m Sprint Time
Sprint time over 5 m will be measured using a single-beam electronic timing system (Witty Gate, Microgate, Bolzano, Italy) during a 30-m maximal sprint. Participants will perform two trials separated by 3 minutes of rest. The average time from the two trials will be used for analysis.
Time frame: From baseline to the post testing at 6 weeks
10-m Sprint Time
Sprint time over 10 m will be measured using a single-beam electronic timing system during a 30-m maximal sprint. Participants will perform two trials separated by 3 minutes of rest. The average time from the two trials will be used for analysis.
Time frame: From baseline to the post testing at 6 weeks
20-m Sprint Time
Sprint time over 20 m will be measured using a single-beam electronic timing system during a 30-m maximal sprint. Participants will perform two trials separated by 3 minutes of rest. The average time from the two trials will be used for analysis.
Time frame: From baseline to the post testing at 6 weeks
30-m Sprint Time
Sprint time over 30 m will be measured using a single-beam electronic timing system. Participants will perform two maximal 30-m sprint trials separated by 3 minutes of rest. The average time from the two trials will be used for analysis.
Time frame: From baseline to the post testing at 6 weeks
Eccentric Hamstring Strength
Eccentric hamstring strength will be assessed using the NordBord device (VALD Performance, Newstead, Australia) during the Nordic hamstring exercise. Following three submaximal familiarization efforts, participants will perform three maximal efforts. The best value obtained for each limb will be used to derive the bilateral eccentric hamstring strength score for analysis.
Time frame: From baseline to the post testing at 6 weeks
Plan to share: No
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