First Time Doing Resisted Sprint Training? Effects of Different Loads on the Force-Velocity Profile and Sprint Performance in Professional Male and Female Football Players and Referees: A Pilot Study

Abstract

Background:

The force-velocity profile (FVP) is essential for understanding sprint performance, capturing parameters such as maximum theoretical force (F₀), maximum theoretical velocity (V₀), and power (P_max). Effective horizontal force application, especially during acceleration, enhances sprinting outcomes. Resisted sprint training (RST) using varied loads (light, moderate, heavy) can improve neuromuscular adaptations, sprint mechanics, and sport-specific performance. This study explores the effects of RST with different load magnitudes.

Hypothesis:

Heavy loads (HL) in athletes with no previous experience in RST are expected to promote better results on sprint performance than light loads (LL) and no loads (CON).

Study Design:

Randomized clinical trial.

Level of Evidence:

Level 3.

Methods:

Professional male and female football players and referees without experience in sled sprint, allocated into HL (80% of body mass [BM]), LL (20% of BM), and CON (0% of BM) groups, performed RST twice weekly over 6weeks, with pre- and postintervention assessments of sprint performance.

Results:

RST with HL significantly improves acceleration, maximum velocity, and horizontal force application. The HL group demonstrated reduced sprint times, enhanced force production during the acceleration phase, and improvements in maximum velocity metrics such as V₀ and maximum velocity (V_max). The LL group showed small benefits in V₀ and decreased times in the 10 meter to 20 meter and 20 meter to 30 meter splits. Intergroup comparisons revealed that the HL group obtained better results compared with the LL and CON groups.

Conclusion:

Both LL and HL improved the right spectrum of the FVP. However, the HL group also improved the acceleration phase variables and force production at low velocity.

Clinical Relevance:

These findings suggest that HL provides superior neuromuscular adaptations and mechanical outputs compared with lighter loads in athletes without previous experience in RST. The inclusion of professional female football players expands the applicability of these results.