The Calf Raise App shows good concurrent validity compared with a linear encoder in measuring total concentric work.

Abstract

The linear encoder and the Calf Raise App have been shown to be valid for measurements of plantar flexor muscular endurance in the heel raise test when compared with gold standard equipment. However, the validity of the Calf Raise App has not yet been compared with a linear encoder, an instrument commonly used in clinical and research settings. The purpose of this study was to determine the concurrent validity of the Calf Raise App compared with a linear encoder for the measurement of average heel raise height and total concentric work in the heel raise test. Fifty TeamGym athletes (82% females) from an on-going prospective study were included (mean [SD] age: 20 [7] years; body mass index (BMI) = 21.3 [2.5]). Concurrent validity was analysed with single measures intraclass correlation coefficient (ICC) using a two-way mixed effects, consistency model. Ninety-eight samples were included in the analysis. The mean (SD) average heel raise height and total concentric work measured by the linear encoder and Calf Raise App were 9.9 (1.4) and 7.5 (1.2) cm, and 1728 (584) and 1291 (450) J, respectively. The mean (SD) number of unilateral heel raises was 30 (7.5). The results showed poor to moderate concurrent validity for the measurement of average heel raise height (ICC: 0.62; 95% confidence interval [CI]: 0.48-0.73). Good to excellent concurrent validity was shown for the measurement of total concentric work (ICC: 0.89; 95% CI: 0.84-0.93). The Calf Raise App shows good concurrent validity in the heel raise test compared with a linear encoder in measuring total concentric work but not average height. While caution is recommended when comparing results from the different instruments, each instrument can be used separately to compare between-limb differences or changes over time in plantar flexor muscular endurance in clinical and research settings. Level III.