Monitoring Fatigue During Intermittent Exercise With Accelerometer-Derived Metrics

Beato, M., De Keijzer, K.L., Carty, B., Connor, M.

The aim of this study was to assess the sensitivity of accelerometer-derived metrics for monitoring fatigue during an intermittent exercise protocol. Fifteen university students were enrolled in the study (age 20 ± 1 years). A submaximal intermittent recovery test (Sub-IRT) with a duration of 6 minutes and 30 seconds (drill 1) was performed. To increase participants’ fatigue, a repeated sprint protocol (1×6 maximal 20 m sprints) was conducted. Following this, participants repeated the Sub-IRT (drill 2) to evaluate the external and internal training load (TL) variations related to fatigue. Apex 10 Hz global navigation satellite system (GNSS) units were used to collect the variables: total distance (TD), high metabolic distance (HMD), relative velocity (RV), average metabolic power (MP), maximal heart rate (HRmax) and mean heart rate (HRmean), muscular (RPEmus) and respiratory rating of perceived exertion (RPEres), dynamic stress load (DSL), and fatigue index (FI). A Bayesian statistical approach was employed. A likelihood difference (between drill 1 and drill 2) was found for the following parameters: TD (BF10 = 0.33, moderate per H0), HMD (BF10 = 1.3, anecdotal), RV (BF10 = 0.29, moderate per H0), MP (BF10 = 1.3, anecdotal), accelerations (BF10 = 1.6, anecdotal), FI (BF10 = 4.7, moderate), HRmax (BF10 = 2.2, anecdotal), HRmean (BF10 = 4.3, moderate), RPEmus (BF10 = 11.6, strong), RPEres (BF10 = 3.1, moderate), DSL (BF10 = 5.7, moderate), and DSL•m−1 (BF10 = 4.3, moderate). In conclusion, this study reports that DSL, DSL•m−1, and FI can be valid metrics to monitor fatigue related to movement strategy during a standardized submaximal intermittent exercise protocol.