Eccentric Squat Loading as means to Assessing Physical Function in Seniors

Healthy aging is a key concern for Canada’s aging population. Investigating methods that assist and promote healthy aging is therefore important to inform on this matter. The maintenance of functional ability, rather, the ability to conduct everyday tasks and perform the functions necessary for everyday life is crucial to assist in the healthy aging process (Lehto et. al., 2017, Arena et. al., 2007). In regard to functional ability, muscle strength and muscle power are two key factors in defining performance. A method of properly assessing these outputs leads to a determination of an individual’s functional performance level and potential interventions to mitigate declining function with age. Traditionally, muscle strength and power have been assessed using an isokinetic dynamometer, but this comes with limitations such as its high cost and the accessibility. \nMuscle strength and muscle power have commonly been maintained through strength and power training. This type of training has limitations that eccentric training may overcome. Isoinertial flywheel devices, such as the kBox (Exxentric), not only have the potential to produce eccentric overload necessary for eccentric training, but they are also capable of recording velocity and power outputs. The kBox may be beneficial to the aging population to determine functional ability and provide a method for eccentric training while overcoming the limitations of the dynamometer. Therefore, investigation into the kBox capabilities regarding the reliability and validity of measured outputs as well as the potential to predict functional ability is necessary.\nThis study had three objectives: 1) To determine the relationship of the kBox power outputs in comparison to the “gold standard” dynamometer. Researchers hypothesized that the kBox would display good validity and be correlated with the measured outputs of the dynamometer; 2) To determine if the kBox measured outputs and/or the dynamometer measured outputs predicted functional performance by comparing outputs to three functional tests. Researchers hypothesized that the kBox would be more predictive of functional performance due to its multi-joint movement; 3) To investigate sEMG and muscle oxygenation levels across the various modalities tested to gain insight into the physiological responses accompanying each movement. Researchers hypothesized the kBox SPT would produce greater muscle activation as well as greater muscle deoxygenation compared to testing on the isokinetic dynamometer. \nA total of 26 strength trained individuals (62.6  6.2 yrs old) were recruited and volunteered to participate in this study. Participants completed three functional tests; the timed-up-and-go test, the five time sit-to-stand test, and the stair climb power test. Participants also completed the kBox Squat Power Test (SPT) as well as dynamometer concentric, isometric and eccentric tests. Muscle activation and muscle oxygenation were recorded across modalities when possible. \nFor the first hypothesis, Pearson’s correlations displayed the flywheel SPT to have high correlations with the dynamometer power and strength outputs, confirming the SPT has high concurrent validity when measuring a senior population during the SPT protocol. For the second hypothesis, the dynamometer results were more predictive of outcomes on the three functional tests than the kBox ( Pearson’s correlation and stepwise multiple linear regression tests). Last, no significant differences between muscle activation or muscle oxygenation were found across modalities through ANOVA and Tukey post-hoc tests.\nResults of this study display the potential the isoinertial kBox has for future clinical settings. The good relationship/validity, along with the prediction of some functional tests demonstrates its usage for further studies and quantification of muscle outputs for various exercises. These findings suggest the kBox may be used in the future to determine functional performance, overcoming the limitations of the dynamometer. Additionally, this study displayed the SPT protocol can be conducted safely and successfully by a senior population meaning the kBox can overcome the limitations set forth by traditional strength and power training such as a decrease in cost for the equipment and easier accessibility for senior population.

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