A comparison of the FitroDyne and GymAware rotary encoders for quantifying peak and mean velocity during traditional multi-jointed exercises

John Fernandes, Kevin L. Lamb, C. C. T. Clark, Jason Moran, Ben Drury, Amador Garcia-Ramos, Craig Twist

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    Abstract

    The FitroDyne and GymAware rotary encoders are being increasingly used in resistance training to monitor movement velocity, but how closely their velocity outcomes agree is unknown. Consequently, this study aimed to determine the level of agreement between the FitroDyne and GymAware for the assessment of movement velocity in three resistance training exercises. Fifteen males performed three repetitions of bench press, back squat and bent-over-row exercises at 10% one repetition maximum increments (from 20 to 80%). For each repetition, the FitroDyne and GymAware recorded peak and mean barbell velocity (cm.s-1). Though strongly correlated (r = 0.79 to 1.00), peak velocity values for the GymAware were significantly lower than the FitroDyne for all exercises and loads. Importantly, the random errors between the devices, quantified via Bland and Altman's 95% limits of agreement, were unacceptable, ranging from ± 3.8 to 25.9 cm.s-1. Differences in mean velocity were smaller (and non-significant for most comparisons) and highly correlated (r = 0.86 to 1.00) between devices. Notwithstanding smaller random errors than for the peak values, mean values still reflected poor agreement (random errors between ± 2.1 to 12.0 cm.s-1). These findings suggest that the FitroDyne and GymAware cannot record peak or mean velocity with acceptable agreement, and should neither be employed interchangeably nor their data compared.
    Original languageEnglish
    JournalJournal of Strength and Conditioning Research
    Early online date1 Nov 2018
    DOIs
    Publication statusE-pub ahead of print - 1 Nov 2018

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