Effects of Resisted Versus Unresisted Sprint Training on Sprint Force-Velocity Profile in Youth Footballers (RST-FV Youth F)

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

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.

Study Overview

• Status: Completed
• Conditions: Sprint Force-Velocity-Power Profile; Football (Soccer) Sprint Performance
• Intervention / Treatment: Other: Resisted Sprint Training; Other: Unresisted Sprint Training

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 Type: Interventional
• Enrollment (Actual): 44
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Colombia
  • Antioquia
    • Medellín, Antioquia, Colombia, 054080
      • Universidad de Antioquia

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child
• Accepts Healthy Volunteers: No

Description

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).

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: 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.	Other: Resisted Sprint Training; 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.
Active Comparator: 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.	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.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change from baseline to post-intervention in best 30 m sprint time	Best (fastest) 30 m sprint time, expressed in seconds (s). The reported value is the best 30 m time (s).	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.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change from baseline to post-intervention in theoretical maximal horizontal force (F0)	Sprint-derived theoretical maximal horizontal force (F0), expressed relative to body mass (N/kg).	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	Peak velocity reached during the sprint assessment, expressed in meters per second (m/s).	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)	Sprint-derived rate of decrease in RF with velocity (DRF), expressed as % per m.	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)	Sprint-derived peak ratio of horizontal force (RF_peak), expressed as percentage (%).	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)	Sprint-derived ratio of horizontal force (RF), expressed as percentage (%).	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)	Sprint-derived maximal horizontal power (Pmax), expressed relative to body mass (W/kg).	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)	Sprint-derived theoretical maximal running velocity (V0), expressed in meters per second (m/s).	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	Countermovement jump (CMJ) height, expressed in centimeters (cm). The reported value is CMJ height (cm).	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.

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change from baseline to post-intervention in stature (standing height)	Stature (standing height), expressed in centimeters (cm).	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 body mass	Body mass, expressed in kilograms (kg).	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 body mass index (BMI)	BMI calculated as body mass (kg) divided by stature squared (m^2), expressed as kg/m^2.	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.

Collaborators and Investigators

• Sponsor: Federal University of Vicosa
• Collaborators: Universidad de Antioquia

Publications and helpful links

General Publications

• Young, J. D., Whitten, J., Reid, J., Quigley, P. J., Low, J., Li, Y., Lima, C., Hodgson, D., Chaouachi, A., Prieske, O., & Granacher, U. (2017). Effectiveness of Traditional Strength vs. Power Training on Muscle Strength, Power and Speed with Youth: A Systematic Review and Meta-Analysis. Frontiers. https://doi.org/10.3389/fphys.2017.0042
• Baena-Raya, A., García-Mateo, P., García-Ramos, A., Rodríguez-Pérez, M., & Soriano-Maldonado, A. (2021). Delineating the potential of the vertical and horizontal force-velocity profile for optimizing sport performance: A systematic review. Journal of Sports Sciences, 40, 331 - 344. https://doi.org/10.1080/02640414.2021.199364 Behm, D. G.,
• Bachero-Mena, B., & González-Badillo, J. (2014). Effects of Resisted Sprint Training on Acceleration With Three Different Loads Accounting for 5, 12.5, and 20% of Body Mass. Journal of Strength and Conditioning Research, 28, 2954-2960. https://doi.org/10.1519/jsc.000000000000049
• Aquino, R., Gonçalves, L. G., Galgaro, M., Maria, T. S., Rostaiser, E., Garcia, G. R., Neto, M. V. M., & Nakamura, F. Y. (2021). Mach running performance in Brazilian professional soccer players: comparisons between successful and unsuccessful teams. https://doi.org/10.31236/osf.io/jm579
• Amore, M., Minciacchi, D., Panconi, G., Guarducci, S., Bravi, R., & Sorgente, V. (2024). Impact of Sled-Integrated Resisted Sprint Training on Sprint and Vertical Jump Performance in Young U-14 Male Football Players. Journal of Functional Morphology and Kinesiology, 9. https://doi.org/10.3390/jfmk9040256
• Alcaraz, P. E., Carlos-Vivas, J., Oponjuru, B. O., & Martínez-Rodríguez, A. (2018). The Effectiveness of Resisted Sled Training (RST) for Sprint Performance: A Systematic Review and Meta-analysis. Sports Medicine, 48(9), 2143-2165. doi:10.1007/s40279-018-0947-8

Study record dates

Study Major Dates

• Study Start (Actual): August 1, 2024
• Primary Completion (Actual): September 20, 2024
• Study Completion (Actual): September 20, 2024

Study Registration Dates

• First Submitted: January 23, 2026
• First Submitted That Met QC Criteria: February 11, 2026
• First Posted (Actual): February 18, 2026

Study Record Updates

• Last Update Posted (Actual): February 18, 2026
• Last Update Submitted That Met QC Criteria: February 11, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Keywords: force-velocity profile; Resisted sprint training; Countermovement jump; Sled towing; Unresisted sprinting; Youth footballers; Horizontal power; RF-peak
• Other Study ID Numbers: CE-042024-6-2024

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No