Data-Driven Gradual Preseason Practice Acclimation Ramp Reduces Lower Extremity Strains in the National Football League

Abstract

Background:

In the National Football League (NFL), approximately 1 in 4 players sustains a lower extremity (LEX) strain each season. Nearly 20% occur in the ~2-week period of training camp at the start of preseason, and LEX strains have a high rate of recurrence.

Purpose:

To examine preseason practice schedule strategies during the first week of training camp in the NFL to identify factors associated with lower injury incidence; use findings to implement an actionable, league-wide injury reduction strategy and evaluate effectiveness.

Study Design:

Descriptive epidemiology study.

Methods:

All players participating during the 2018-2023 seasons were included in this observational study. Injury data from the league-wide electronic medical record were combined with wearable player tracking data and practice schedules. Club practice patterns were analyzed and described and then grouped into strategies. Primary outcomes were hamstring, quadriceps, adductor, and calf LEX strains. Incidence rates per club practice and 95% CIs were calculated.

Results:

Between 2018 and 2021, a total of 5 acclimation practice schedule strategies over the first 3 practices were identified from 82 club-seasons: gradual 15-minute ramp (increasing duration 15 minutes each day), <10-minute ramp (increasing duration <10 minutes each day), high-low duration variation (varying duration), stable duration, and reverse ramp (decreasing duration each day). Clubs using the gradual 15-minute ramp, <10-minute ramp, or high-low duration variation had lower training camp LEX strain rates per club-practice compared with the other strategies (Incidence rate ratio = 0.81; 95% CI, 0.68-0.95; P = .01). Results were communicated to stakeholders before the 2022 preseason, and a mandatory league-wide gradual practice acclimation ramp was implemented by the NFL and NFL Players Association as part of the Collective Bargaining Agreement, coupled with mandatory club one-on-one education sessions to explain the requirements. League-wide LEX strain incidence during training camp decreased from 288 in 2021 to 215 in 2022 and 186 in 2023. Additionally, recurrent LEX strains in the regular season decreased from 22 per year in 2021 to 11 per year in 2022-2023.

Conclusion:

A mandated gradual practice acclimation ramp in training camp coupled with education around strategic load management was associated with reduced LEX strains in the NFL. After the intervention, league-wide LEX strain incidence during training camp decreased by 35%.