A Novel Accelerometry-Based Metric to Improve Estimation of Whole-Body Mechanical Load

Abstract

While the Player Load is a widely-used parameter for physical demand quantification using wearable accelerometers, its calculation is subjected to potential errors related to rotational changes of the reference frame. The aims of this study were (i) to assess the concurrent validity of accelerometry-based Player Load against force plates; (ii) to validate a novel metric, the Accel’Rate overcoming this theoretical issue. Twenty-one recreational athlete males instrumented with two triaxial accelerometers positioned at the upper and lower back performed running-based locomotor movements at low and high intensity over six in-series force plates. We examined the validity of the Player Load and the Accel’Rate by using force plates. Standard error of the estimate was small to moderate for all tested conditions (Player Load: 0.45 to 0.87; Accel’Rate: 0.25 to 0.95). Accel’Rate displayed trivial to small mean biases (−1.0 to 6.1 a.u.) while the Player Load displayed systematic very large to extremely large mean biases (17.1 to 226.0 a.u.). These findings demonstrate a better concurrent validity of the Accel’Rate compared to the Player Load. This metric could be used to improve the estimation of whole-body mechanical load, easily accessible in sport training and competition settings.

Peak Locomotor Intensity in Elite Handball Players: A First Insight Into Player Position Differences and Training Practices

“…Additionally, we calculated the Accel’Rate (a.u.) from the raw inertial data (100 Hz) as an overall measure of mechanical load (18). Accel’Rate was calculated as follows:Accel'Rate=|(axi)2+(ayi)2+(azi)2 − (axi−1)2+(ayi−1)2+(azi−1)2|,where ax is the mediolateral acceleration, ay is the anteroposterior acceleration, and az is the vertical acceleration.…”

“…For more readability, the final value obtained was divided by 100. This variable was chosen because the Accel’Rate was recently shown to better reflect the mechanical load than the classical PlayerLoad (18).…”

Simulated Game-Based Ice Hockey Match Design (Scrimmage) Elicits Greater Intensity in External Load Parameters Compared With Official Matches

“…At last, different calculations of acceleration load (i.e., PlayerLoad™, on ice load, Accel'Rate) used in the literature complicate comparison and interpretation of the results. Indeed, the PlayerLoad TM calculations have recently been suggested to have limitations for estimating whole-body mechanical load (Hollville et al, 2021 ), and its relevance in ice hockey is not investigated. Implementation of Accel'Rate has been suggested as a more sensitive measure (Hollville et al, 2021 ) and has indeed been applied in ice hockey (Perez et al, 2020 ) and future studies should assess its relevance compared to the traditional use of PlayerLoad TM .…”

Weekly Training Demands Increase, but Game Demands Remain Consistent Across Early, Middle, and Late Phases of the Regular Season in Semiprofessional Basketball Players

“…PL (coefficient of variation [CV] = 0.9-1.9%) 17 and IMA variables (CV = 3.1-6.7%) 18 have been shown to possess acceptable reliability in team sport research. PL has been reported to be valid compared to accelerations measured with a force plate (r = 0.74-0.90) 19 and distance measured with global positioning systems (r = 0.79) 20 during sport-based movement tasks performed in different directions and at different intensities.…”