The Influence of Weekly Sprint Volume and Maximal Velocity Exposures on Eccentric Hamstring Strength in Professional Football Players

Background: Hamstring strains are the most common moderate-major severity injuries in football. The majority of hamstring injuries occur during sprinting, with low eccentric hamstring strength being associated with an elevated risk. Objective: To examine the relationship between sprinting and eccentric hamstring strength by monitoring total weekly sprint distance and weekly efforts > 90% and >95% of maximum velocity. Methods: Fifty-eight professional male footballers were observed over one-and-a-half seasons. Players’ running was monitored during training and matches using GPS, and eccentric hamstring strength was measured weekly. Results: Weekly sprint distance (ρ = −0.13, p 90% of maximum velocity (ρ = −0.08, p = 0.01) both displayed significant inverse relationships with the percentage change in eccentric hamstring strength; weekly efforts >95% of maximum velocity showed no relationship with hamstring strength (ρ = −0.02, p = 0.45). Only weekly efforts >90% of maximum velocity significantly influenced the mean percentage change in eccentric hamstring force, F((3,58)) = 3.71, p = 0.01, with significant differences occurring when comparing 7–8 sprint efforts with 0–2 efforts (0.11%, p = 0.03) and 5–6 efforts (0.12%, p = 0.03). Conclusions: Eccentric hamstring strength levels significantly decrease when 7–8 weekly sprint efforts are completed at >90% of maximum velocity. Monitoring weekly sprint loading at velocities > 90% of maximum velocity may be valuable to help to reduce the risk of hamstring injuries in professional football

The Influence of Weekly Sprint Volume and Maximal Velocity Exposures on Eccentric Hamstring Strength in Professional Football Players

Background: Hamstring strains are the most common injuries of moderate and major severity in football. To reduce the risk of these injuries it is important to understand the mechanisms and risk factors that cause them. Sprinting is the primary cause of hamstring injuries, with eccentric hamstring strength identified as a risk factor. Objective: To identify any relationships between sprinting and eccentric hamstring strength by investigating the influence of total weekly sprint distance (m) and weekly efforts >90% and >95% of an individual’s maximum velocity on the eccentric force output of the hamstring muscles. Methods: Fifty-eight professional male football players were observed over one and a half football seasons. The players’ weekly movements and speeds were monitored during training and matches using GPS, while eccentric hamstring strength was measured during the Nordic Hamstring Exercise, on the NordBord, as part of their weekly strength and conditioning session. Results: Weekly sprint distance (ρ = -0.13, P 90% of maximum velocity (ρ = -0.08, P = 0.01) both had significant inverse relationships with percentage change in eccentric hamstring strength, with very small correlations; however, total weekly efforts >95% of maximum velocity showed no relationship (ρ = -0.02, P = 0.45). Only weekly efforts >90% of maximum velocity significantly influenced the mean percentage change in eccentric hamstring force, F (3, 58) = 3.71, P = 0.01, with significant differences occurring when comparing 7-8 sprint efforts with 0-2 efforts (0.11%, P = 0.03) and 5-6 efforts (0.12%, P = 0.03). Conclusion: Eccentric hamstring strength levels significantly decrease when 7-8 weekly sprint efforts are completed at a maximum velocity >90% but are not significantly influenced by total weekly sprint distance or the weekly number of sprint efforts completed at a maximum velocity >95%