Elite football teams that do not have a winter break lose on average 303 player-days more per season to injuries than those teams that do: a comparison among 35 professional European teams

Chinese soccer players sprint during their training session for the upcoming AFC Asian Cup soccer tournament in Kuala Lumpur July 6, 2007. REUTERS/Zainal Abd Halim (MALAYSIA)

Most European elite football leagues have a winter break that coincides with the middle of the football season. However, in England there is no scheduled winter break. The effect of the absence of a winter break on injury rates has not been investigated. 

This study aimed to compare injury rates among professional men’s football teams that have a winter break in their league season schedule with corresponding rates in teams that do not.

The studyincluded 56 teams from 15 European countries during seven consecutive seasons (2010/2011 to 2016/2017) with a total of 206 team seasons. All teams participated in the highest level of domestic competition and some also participated regularly in the UEFA Champions League or Europa League competitions.Teams from 14 different countries (35 teams, 131 team seasons) had winter break; only English teams (21 teams, 75 team seasons) did not have it.

During the study period, individual player participation in training and matches was registered. The team medical staff recorded injuries including information about the diagnosis, nature and circumstances of the injury occurrence. Injury absence was measured as the number of days from injury occurrence to full participation.

Four different types of team injury rates were used as dependent variables: (1) injury burden, (2) incidence of severe injuries, (3) team training attendance and (4) team match availability. Injury burden was expressed as the sum of lay-off days/sum of exposure hours per 1000 hours of football training and match play. Incidence of severe injuries was calculated as the sum of severe injuries (defined as injuries causing absence of more than 28 days)/sum of exposure hours per 1000 hours of football training and match play. The four key outcomes were evaluated over four different periods: the whole season, the period between the beginning of the season and the winter break (August to December), the period immediately following the winter break (January to March) and the period at the end of the season (April to May). Linear regression was performed on team-level data to analyse the effect of winter break on each of the injury rates.

Crude analyses and analyses adjusted for climatic region were performed. Teams were categorised into two different climatic types: the ‘southern’ group represented teams from the Mediterranean region (14 teams, 48 team seasons), and the ‘northern’ group represented teams from the middle and north of Europe (42 teams, 158 team seasons).

In total, the 206 teams had 9627 injuries (4240 training, 5387 match play) during 1 440 721 hours of football training and match play. The mean length of the winter break was 10.0 days with a range of 0–27 days, and the mean exposure time during the season was approximately 6994 hours per team.

The mean injury burden was 185.9 days lost/1000 hours (1300 days lost per season) for teams without a winter break and 127.0 days lost/1000 hours (888 days lost per season) for the whole season for teams with a winter break. The adjusted analysis showed that teams without a winter break lost on average 303 days more per season due to injuries than teams with a winter break during the whole season (p<0.001). The results were similar across the three periods: August–December (228 days lost more for teams without a winter break, p=0.013), January–March (466 days lost more for teams without a winter break, p<0.001) and April–May (267 days lost more for teams without a winter break, p=0.050).

Climatic region had no significant impact on the association between winter break and injury burden for any of the four periods studied. 

Teams without a winter break had a mean of 1.6 severe injuries per season; the corresponding incidence for teams with a winter break was 1.1. Teams without a winter break also had a higher incidence of severe injuries during the period of January–March (p=0.003).

There was no association between the absence of a winter break and the attendance of players at team training or in match availability.

The findings demonstrate that the absence of a winter break has negative effects on injury burden both before and after the break, while the absence of a winter break has negative effects on the incidence of severe injuries only immediately after, but not before the break. This study provides club medical teams where there is no winter break with compelling data to encourage their clubs to engage in winter break programmes and thus avoid the negative consequences of chronic fatigue. 

Source: Ekstrand J et al. (2018) Elite football teams that do not have a winter break lose on average 303 player-days more per season to injuries than those teams that do: a comparison among 35 professional European teams. Br J Sports Med. doi:10.1136/bjsports-2018-099506