Monitoring loads and non-contact injury during the transition from club to national team prior to an international football tournament: A case study of the 2014 FIFA world cup and 2015 Asia cup

Objectives
Injured and non-injured national team footballers were compared for external and internal loads during transition from club to National team training camp.
Design
Prospective Case Study.
Methods
Load and injury data were collected from the same National team prior to and during training camps of 2 tournaments; World (n = 17) and Asian Cups (n = 16). External (number sessions) and internal (s-RPE) loads were collected 4-weeks prior to and during camps. The acute:chronic load ratio was calculated for the first week of camp based on the mean of previous 4-weeks. Respective loads and ratios were compared between injured and non-injured players for non-contact injuries occurring during camp.
Results
Seven non-contact injuries occurred during World Cup camp and 1 during Asian Cup (preventing statistical analyses). Small-to-moderate effect sizes were found for lower chronic internal loads (ES = 0.57; 90% CI: 0.39–1.08) and higher acute:chronic ratio (ES = 0.45; 90% CI: 0.31–0.87) for injured compared to non-injured players. Moderate-large effects (ES = 0.83; 90% CI: 0.56–1.60) were evident for increased acute:chronic ratio for number of sessions in injured compared to non-injured players. However, small-moderate effect sizes were present for lower chronic training and match loads (ES = 0.55; 90% CI: 0.38–1.06) in injured players prior to the World Cup camp, alongside an increased number of sessions in week 1 of camp (ES = 0.47; 90% CI: 0.33–0.91).
Conclusions
Players incurring non-contact injury during training camp prior to an international tournament performed less prior chronic external and internal load and a concomitant higher relative increase in camp, thus representing a practical marker to monitor in national teams.