Concurrent validity of an inertial sensor for measuring muscle mechanical properties

Background: The usage of the Force-Velocity relationship for individualizing training regimes for athletes has increased in popularity. This can be done through measurements of muscle mechanical properties and creating individual force-velocity profiles. To do this, one must use valid and reliable test equipment. These types of equipment are often expensive and impractical, which limits the usage to a small population with the right financial means. Therefore, the purpose of this study was to examine the concurrent validity of the inertial sensor Vmaxpro for measuring muscle mechanical properties. Method: 52 male ice-hockey players (age:17.9 ± 2.2 years, body weight: 77.7 ± 10.6 kg, height: 180.3 ± 6.2 cm) participated in this study and performed two jumps each on four different loading conditions (unloaded, 25, 50 and 75% of BW). The jumps were recorded simultaneously with an inertial sensor and a linear transducer. Three different variables were analyzed: peak velocity (pV), average velocity (avgV) and average power (avgP). Pearson’s correlation coefficient (r), linear regression analysis, Bland-Altman analysis, and standard error of estimate (SEE) was used to examine the concurrent validity. Results: The results showed a strong correlation, agreement and small SEE for pV: r=0.98, bias = -0.12, SEE = 0.08, for avgV: r=0.98 bias = 0.01, SEE = 0.04 and for avgP: r = 0.97, bias = 30.94, SEE = 73.47. Practical application: The results from the present study indicate that the Vmaxpro can be used for assessing muscle mechanical properties. Furthermore, since the Vmaxpro is both cheap and portable, it can potentially expand the usage of test equipment to clubs and associations with limited budgets