Effects of Resisted Versus Non-resisted Sprint Training on Countermovement Jump and Sprint Force-velocity Profile in Youth Footballers: a Randomised Controlled Trial
Trial Snapshot
- Phase
- Not Applicable
- Status
- Completed
- Sponsor
- Enrollment
- 44
- Locations
- 1
- Primary Endpoint
- Change from baseline to post-intervention in best 30 m sprint time
Study Overview
Brief Summary
This randomised, controlled, two-arm trial evaluates whether light resisted sprint training (sled towing at 20% of body mass) produces superior improvements in 30 m sprint mechanical outputs compared with matched-dose unresisted sprint training in youth footballers.
Participants complete two supervised sessions per week for six consecutive weeks, integrated into normal academy microcycles on the same artificial-turf surface. Primary outcomes are changes in sprint-derived force-velocity-power profile parameters and 30 m sprint performance, with secondary outcomes including countermovement jump height and anthropometrics.
Detailed Description
The study uses a parallel-group randomised design. Allocation is stratified by squad category (Under-14 and Juvenile) with simple randomisation within strata using computer-generated random numbers prepared by a researcher not involved in training delivery.
The intervention is delivered on a third-generation artificial-turf pitch at a youth academy integrated within a professional development pathway. Forty-four outfield players from two squads are enrolled.
Both arms complete 20 m maximal sprints with identical volume and rest structure (3 sets × 5 repetitions, 45 s inter-repetition rest, 3 min inter-set rest). The experimental arm performs sled towing at 20% body mass (sled tare 3 kg plus plates), whereas the comparator arm performs unresisted maximal sprints. No additional lower-limb strength or speed work beyond the head coach's standard plan is introduced during the intervention period.
Primary outcomes are derived from 30 m sprint profiling, using high-speed video and the MySprint application to compute split times and estimate sprint mechanical variables within the Morin-Samozino framework. Outcome assessors/video analysts and the statistician are blinded to group codes, while full participant blinding is not feasible due to the presence of the sled.
Study Design
- Study Type
- Interventional
- Allocation
- Randomized
- Intervention Model
- Parallel
- Primary Purpose
- Treatment
- Masking
- Single (Outcomes Assessor)
Eligibility Criteria
- Ages
- 13 Years to 17 Years (Child)
- Sex
- Male
- Accepts Healthy Volunteers
- No
Inclusion Criteria
- •Male football (soccer) player aged 13 to 17 years.
- •Registered Under-14 or Juvenile player in an organized football program/club/league.
- •At least 1 year of organized football experience.
- •Current health-system affiliation (e.g., EPS).
- •Provided informed assent; parent/guardian provided written informed consent (for minors).
- •Able to attend and comply with the sessional training and testing protocol.
Exclusion Criteria
- •Current musculoskeletal complaint or injury at baseline.
- •Ongoing rehabilitation at baseline.
- •Logistical constraints preventing participation in the sessional protocol (e.g., inability to attend required sessions/assessments).
- •Injury incurred during the intervention that prevents safe continuation (participant will be withdrawn).
Arms & Interventions
Resisted Sprint Training (RST)
20 m maximal sprints towing a sled loaded to 20% of individual body mass (sled tare 3 kg; plates added). 3 sets × 5 repetitions, 45 s inter-rep rest, 3 min inter-set rest; two supervised sessions/week for six weeks, conducted at the start of squad training, on the same artificial-turf surface.
Intervention: Resisted Sprint Training (Other)
Unresisted Sprint Training
20 m maximal sprints without external resistance; dose and rest schedule identical to RST (3 × 5 × 20 m; 45 s; 3 min); two sessions/week for six weeks; same surface and session placement; standard team training continues.
Intervention: Unresisted Sprint Training (Other)
Outcomes
Primary Outcomes
Change from baseline to post-intervention in best 30 m sprint time
Time Frame: From baseline assessment (within 1 week prior to first training session) to post-intervention assessment (within 1 week after the final training session), over the 6-week intervention period.
Best (fastest) 30 m sprint time, expressed in seconds (s). The reported value is the best 30 m time (s).
Secondary Outcomes
- Change from baseline to post-intervention in theoretical maximal horizontal force (F0)(From baseline assessment (within 1 week prior to first training session) to post-intervention assessment (within 1 week after the final training session), over the 6-week intervention period.)
- Change from baseline to post-intervention in peak sprint velocity(From baseline assessment (within 1 week prior to first training session) to post-intervention assessment (within 1 week after the final training session), over the 6-week intervention period.)
- Change from baseline to post-intervention in rate of decrease in RF with velocity (DRF)(From baseline assessment (within 1 week prior to first training session) to post-intervention assessment (within 1 week after the final training session), over the 6-week intervention period.)
- Change from baseline to post-intervention in peak ratio of horizontal force (RF_peak)(From baseline assessment (within 1 week prior to first training session) to post-intervention assessment (within 1 week after the final training session), over the 6-week intervention period.)
- Change from baseline to post-intervention in ratio of horizontal force (RF)(From baseline assessment (within 1 week prior to first training session) to post-intervention assessment (within 1 week after the final training session), over the 6-week intervention period.)
- Change from baseline to post-intervention in maximal horizontal power (Pmax)(From baseline assessment (within 1 week prior to first training session) to post-intervention assessment (within 1 week after the final training session), over the 6-week intervention period.)
- Change from baseline to post-intervention in theoretical maximal running velocity (V0)(From baseline assessment (within 1 week prior to first training session) to post-intervention assessment (within 1 week after the final training session), over the 6-week intervention period.)
- Change from baseline to post-intervention in countermovement jump (CMJ) height(From baseline assessment (within 1 week prior to first training session) to post-intervention assessment (within 1 week after the final training session), over the 6-week intervention period.)