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Completed

NCT Number: NCT07418892

Effects of Resisted Versus Unresisted Sprint Training on Sprint Force-Velocity Profile in Youth Footballers

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.

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Key information

Conditions

Sprint Force-Velocity-Power Profile Football (Soccer) Sprint Performance

Age range

13 year–17 year

Sex eligibility

Male

Study type

Interventional

Phase

Not applicable

Primary location

Universidad de Antioquia

Medellín, Antioquia, 054080, Colombia

About this study

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.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

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).

Treatment and study plan

Resisted Sprint Training

Other

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.

Unresisted Sprint Training

Other

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.

Primary outcomes

  1. 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

  1. Change from baseline to post-intervention in theoretical maximal horizontal force (F0)

    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.

    Sprint-derived theoretical maximal horizontal force (F0), expressed relative to body mass (N/kg).

  2. Change from baseline to post-intervention in peak sprint velocity

    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.

    Peak velocity reached during the sprint assessment, expressed in meters per second (m/s).

  3. Change from baseline to post-intervention in rate of decrease in RF with velocity (DRF)

    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.

    Sprint-derived rate of decrease in RF with velocity (DRF), expressed as % per m.

  4. Change from baseline to post-intervention in peak ratio of horizontal force (RF_peak)

    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.

    Sprint-derived peak ratio of horizontal force (RF_peak), expressed as percentage (%).

  5. Change from baseline to post-intervention in ratio of horizontal force (RF)

    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.

    Sprint-derived ratio of horizontal force (RF), expressed as percentage (%).

  6. Change from baseline to post-intervention in maximal horizontal power (Pmax)

    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.

    Sprint-derived maximal horizontal power (Pmax), expressed relative to body mass (W/kg).

  7. Change from baseline to post-intervention in theoretical maximal running velocity (V0)

    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.

    Sprint-derived theoretical maximal running velocity (V0), expressed in meters per second (m/s).

  8. Change from baseline to post-intervention in countermovement jump (CMJ) height

    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.

    Countermovement jump (CMJ) height, expressed in centimeters (cm). The reported value is CMJ height (cm).

Other outcomes

  1. Change from baseline to post-intervention in stature (standing height)

    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.

    Stature (standing height), expressed in centimeters (cm).

  2. Change from baseline to post-intervention in body mass

    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.

    Body mass, expressed in kilograms (kg).

  3. Change from baseline to post-intervention in body mass index (BMI)

    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.

    BMI calculated as body mass (kg) divided by stature squared (m^2), expressed as kg/m^2.

Sponsors and collaborators

Lead sponsor

Federal University of Vicosa

Other

Collaborators

  • Universidad de Antioquia

Registry information

Official study title

Effects of Resisted Versus Non-resisted Sprint Training on Countermovement Jump and Sprint Force-velocity Profile in Youth Footballers: a Randomised Controlled Trial

Acronym: RST-FV Youth F

Important dates

Study start
2024
Primary completion
2024
Study completion
2024
First posted
Feb 18, 2026
Registry last updated
Feb 18, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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