Reliability and Validity of the Heel Rise Test Using the Mobile Application

Background. The heel-rise test is a measurement method that can evaluate the muscle endurance and muscle fatigue of the plantar flexor. On the other hand, there is a limit to quantifying the criteria because the evaluation method and criteria differ according to the measurement conditions. Objectives. The purpose of this study is to compare the validity and reliability of the smartphone-based measurement application compared to the standardized surface electromyography (sEMG) for measuring muscle fatigue during the heel-rise test.Methods. Fifty-seven adults in their 20s participated in the heel-rise test twice a week apart. The concurrent validity for muscle fatigue during the heel-rise test was measured using surface sEMG and 'Calf raise' application, and analyzed through correlation analysis. The intra-rater reliability and inter-rater reliability of the 'Calf raise' application were analyzed using ICC.Results. The Pearson correlation coefficient between the 'Calf raise' application and sEMG showed a statistically significant correlation of r=0.509 for both loss (%) and slope value (p<0.01). The 'Calf raise' application showed high intra-rater reliability for loss (%) and slope value with ICC (2,1) = 0.986 and 0.987 respectively. It also showed high inter-rater reliability for loss (%) and slope value with ICC (2,1) =0.946 and 0.926. Conclusion. The smartphone-based 'Calf rise' application can be usefully used in clinical practice as an evaluation tool capable of not only quantitative evaluation of counting the number of heel-rise tests but also qualitative evaluation of muscle fatigue.