Sudden increases in weekly external workload are related to muscle-tendon injuries in professional male football players

The aim of this study was to analyse how sudden increases in external workload may lead to muscle-tendon injuries in professional Spanish football players. Twenty-six male football players were monitored for 2 seasons and 38 muscle-tendon injuries were registered (including 15 hamstring strains). Cumulative workload parameters were compared for the week prior to the injury vs a normative-control period (6 weeks prior to injury). For muscle-tendon injuries, higher workload values were observed during the week prior to injury in all the analysed workload parameters when compared to the normative-control period [percentage of change (Δ%) = +16.08 to 36.64%; p < 0.001 to 0.012]. In the sub-analysis of hamstring strains, higher workload values were obtained in total distance (Δ% = +19.28; p = 0.026), HSR (Δ% = +25.38; p = 0.014), sprint running (Δ% = +41.78; p = 0.002), number of sprints (Δ % = +34.69; p = 0.005), low accelerations (Δ% = +18.36; p = 0.047), and high decelerations (Δ%= +23.32; p = 0.031) for the week prior to the injury. Muscle-tendon injuries and hamstring strains were preceded by training/competition week with 18–40% greater external workloads. These outcomes highlight the importance of monitoring and controlling external workload during the microcycle to avoid workload spikes.