Validity and Reliability of Inertial Measurement System for Linear Movement Velocity in Flywheel Squat Exercise

Abstract

The aim of this study was to examine the validity and reliability of an Inertial Measurement System integrated into a secondary pulley (IMS) for determining linear velocity during flywheel squat exercises. Thirty-one male participants who were highly experienced in a flywheel resistance exercise training performed flywheel squat exercises with three incremental loads, and mean velocity (MV), mean propulsive velocity (MPV) and max velocity (Vmax) of the exercises were simultaneously recorded with a validated linear encoder and the IMS, in two different sessions. Validity was analyzed using ordinary least products regression (OLP), Lin’s concordance correlation coefficient (CCC), and Hedge’s g for the values from the linear encoder and the IMS. Test-retest reliability was determined by coefficient of variation (CV), Intraclass correlation coefficient (ICC), and standard error of measurement (SEM). Results showed a high degree of validity (OLP intercept = −0.09–0.00, OLP slope = 0.95–1.04, CCC = 0.96–0.99, Hedge’s g < 0.192, SEM = 0.04–0.08) and reliability (CV < 0.21%, ICC > 0.88, SEM < 0.08). These results confirm that the IMS provides valid and reliable measures of movement velocity during flywheel squat exercises.

Test-Retest and Inter-Rater Reliability of a Rotary Axis Encoder-Flywheel System for the Assessment of Hip Rotation Exercises

“…Additionally, some studies have focused on the reliability of the encoderflywheel system. Maroto-Izquierdo et al [10] and Martín-Rivera et al [12] achieved an ICC exceeding 0.88 when assessing velocity with a flywheel-squat exercise using a linear encoder. On the other hand, some studies investigated the reliability of a rotary axis encoder-flywheel system in both multi-joint exercises (squat, half squat, lunge) [7,35] or single-joint exercises (leg curl) [2].…”

“…They have become a useful option for resistance training, due to their immediate effect in post-activation potentiation (PAP), obtaining greater responses than power or conventional training [8]. Moreover, this type of training promotes neuromuscular adaptations, and also enhances muscle strength, power, and hypertrophy [2,7,[9][10][11]. Notwithstanding, flywheel devices have not been used as assessment tools in clinical settings yet.…”

“…Flywheel devices can be used attached to linear and rotary axis encoders. Linear encoders allow the analysis of kinematics based on concentric and eccentric phases to be evaluated separately [10,12]. Rotary encoders are devices connected to the main axis of rotation, which are used to monitor kinematic data during the execution of flywheel exercises.…”

“…Rotary encoders are devices connected to the main axis of rotation, which are used to monitor kinematic data during the execution of flywheel exercises. They primarily provide pooled concentric-eccentric information related to angular velocity, supplying data of force and power [10,13]. Consequently, rotary axis encoders could identify intraindividual changes and compare performance development between subjects [14,15].…”

“…The encoder-flywheel system has shown adequate validity when compared to IDs [16,17]. Nevertheless, the reliability of these devices has only contrasted for functional movements like squats or quarter squats [7,10,18,19]. The reliability of physical performance tests depends not only on the joint and the executed movement, but also on the measurement protocol, including the assessment position and the fixation system, like with IDs [4].…”