Reliability and validity of impact absorption rate using accelerometers during single-leg drop-jump landings

[Purpose] To assess the reliability and validity of accelerometer-based impact absorption rate measurements during single-leg drop-jump landings. [Participants and Methods] Study participants were healthy adult males. The task involved a single-leg drop-jump from the platform with a forward landing onto a floor reaction force plate. Accelerometers were fastened to the trunk, while foot switches were attached to the forefoot plantar surfaces. The impact absorption rate was calculated as the peak composite acceleration during the single-leg drop-jump landing divided by the duration from foot contact to the attainment of peak value. The loading rate (LR) was calculated by dividing the peak vertical force by the duration from foot contact to the attainment of peak value, leveraging the data obtained from a floor reaction force plate. Intraclass correlation coefficients (ICC) were used for intra- and inter-rater reliability analyses of 18 and 12 participants, respectively. The validity was examined through the correlation between impact absorption rate and LR in the 18 participants. [Results] The intra- (ICC (1,1)) and inter-rater (ICC (2,1)) reliabilities for the impact absorption rates were 0.89 and 0.88, respectively. A significant positive correlation was observed between impact absorption rates and LR (r=0.71). [Conclusion] The impact absorption rate may be valuable in clinical practice.