Abstract
The COVID-19 pandemic has produced a major disruption for professional football leagues that has affected the physical preparation of both football players and referees. In Spain, health authorities decreed home confinement for eight weeks, supressing the normal training routines of professional referees. After home confinement, referees had four weeks to retrain as the national football league was set to resume matches to complete the 11 games remaining. The aim of the present investigation was to assess changes in eccentric hamstring muscle strength during football competition suspension/resumption due to the COVID-19 pandemic in 21 professional football referees (mean ± SD, age: 33.4 ± 5.1 years; height: 182.4 ± 5.0 cm; body mass: 75.1 ± 4.4 kg). Eccentric hamstring muscle strength was measured with the Nordic hamstring exercise at four time points. During home confinement, referees presented the lowest value of bilateral eccentric muscle strength (300 ± 14 N). Eccentric muscle strength increased by 13.2 ± 3.7% one week after the end of home confinement (339 ± 16 N; p = 0.001, effect size (ES) = 2.8) and remained stable before the first match (343 ± 17 N; p = 0.001, ES = 3.1) and after the end of the national league (328 ± 13 N; p = 0.001, ES = 2.0). In summary, home confinement produced detraining effects in professional football referees associated with hamstring muscle weakness. In this regard, strength-based activities with body loads may be insufficient to avoid muscle weakness and other means (e.g., weights) may be necessary to maintain muscle strength. However, the 4-weeks retraining period was sufficient to resolve hamstring muscle weakness induced by the restrictions of home confinement. This information may be helpful in the case of future sport competition suspension or home quarantine due to new waves of COVID-19 pandemic.
Highlights
Several investigations have described the external physical demands of professional football refereeing during an official match [1,2,3,4]
In comparison to the measurement during confinement, bilateral eccentric muscle strength increased by 13.2 ± 3.7% (p = 0.001, effect size (ES) = 2.8) in the post-confinement trial and remained stable in the pre-competition (p = 0.001, ES = 3.1)
The unilateral measurements followed a similar pattern; in the post-confinement measurement muscle strength increased by 10.6 ± 1.9% in the left limb (p < 0.001, ES = 1.6) and by 14.3 ± 4.9% in the right limb (p = 0.002, ES = 2.3) with respect to the confinement
Summary
Several investigations have described the external physical demands of professional football (soccer) refereeing during an official match [1,2,3,4]. That investigation showed that players suffered muscle weakness during home confinement despite training at home with specific exercises to maintain muscle strength in all the structures of the lower limbs It is unknown if the retraining period before the resumption of the football league was effective to diminish the detraining effect of home confinement. For this reason, the aim of the present investigation was to assess changes in eccentric hamstring muscle strength during football competition suspension/resumption due to the COVID-19 pandemic in professional football referees. We hypothesised that home confinement due to COVID-19 pandemic would induce lower eccentric hamstring muscle strength in professional referees
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