Injury Risk-Workload Associations in NCAA American College Football

Sampson, J.A., Murray, A., Williams, S., Halseth, T., Hanisch, J., Golden, G., Fullagar, H.H.K.

Objectives:
To determine injury risk-workload associations in collegiate American Football.

Design:
Retrospective analysis.

Methods:
Workload and injury data were recorded from 52 players during a full NCAA football season. Acute, chronic, and a range of acute:chronic workload ratios (ACWR: 7:14, 7:21, and 7:28 days) calculated using rolling and exponentially weighted moving averages (EWMA) were plotted against non-contact injuries (regardless of time lost or not) sustained within 3- and 7-days. Injury risks were also determined relative to position and experience.

Results:
105 non-contact injuries (18 game- and 87 training-related) were observed with almost 40% sustained during the pre-season. 7–21 day EWMA ACWRs with a 3-day injury lag were most closely associated with injury (R^2 = 0.54). Relative injury risks were >3× greater with high compared to moderate and low ratios and magnified when combined with low 21-day chronic workloads (injury probability = 92.1%). Injury risks were similar across positions. ‘Juniors’ presented likely and possibly increased overall injury risk compared to ‘Freshman’ (RR: 1.94, CI 1.07–3.52) and ‘Seniors’ (RR: 1.7, CI 0.92–3.14), yet no specific ACWR–experience or–position interactions were identified.

Conclusions:
High injury rates during college football pre-season training may be associated with high acute loads. In-season injury risks were greatest with high ACWR and evident even when including (more common and less serious) non-time loss injuries. Substantially increased injury risks when low 21-day chronic workloads and concurrently high EWMA ACWR highlight the importance of load management for individuals with chronic game- (non-involved on game day) and/or training (following injury) absences.