Contraction Velocity of the Elbow Flexors Assessed by Tensiomyography: A Comparison Between Formulas.

Mesquita, RNO, Latella, C, Ruas, CV, Nosaka, K, and Taylor, JL. Contraction velocity of the elbow flexors assessed by tensiomyography: A comparison between formulas. J Strength Cond Res XX(X): 000-000, 2023-Muscle contraction velocity (Vc) assessed by tensiomyography is a promising measure for athlete profiling. Multiple formulas are used to estimate Vc, but the most suitable method is yet to be established. Fifteen adults (2 female subjects) underwent tensiomyography assessment of biceps brachii muscle at 10, 45 and 90° of elbow flexion on 2 separate days. Vc was calculated using 6 formulas. Formulas 1 and 2 are measures of the early phase of the twitch; Formulas 3-5 are measures over a wider time-window, with Formula 5 normalizing Vc to maximal displacement (Dm); and we proposed Formula 6 as a measure of peak Vc. Test-retest reliability, the required minimum number of trials, proportional bias, and effects of joint angle were investigated. Higher reliability (coefficient of variation: 2.8-6.9%) was found for Formula 1 (0-2 mm of displacement) and Formula 5 (normalized 10-90% of Dm). Overall, a minimum of 6-7 trials was required to obtain reliable estimates. For 10° only, significant positive proportional bias (r = 0.563-0.670) was found for all formulas except Formula 5. Vc was faster (p < 0.001) at shorter muscle lengths for all formulas except Formula 5 (p = 0.06). Vc in the early phase of the twitch was more reliable when calculated using absolute displacement (Formula 1) than a relative threshold (Formula 2). Over a larger time-window, Formulas 3 and 4 were similarly reliable. Because they are derived from different components of the twitch and different parameters, the different formulas should not be used interchangeably. Additionally, more precise nomenclature is required to describe the information obtained from each formula.