Abstract
Objective: Handheld dynamometers are common tools for assessing/monitoring muscular strength and endurance. Health/fitness Bluetooth load sensors may provide a cost-effective alternative; however, research is needed to evaluate the validity and reliability of such devices. This study assessed the validity and reliability of two commercially available Bluetooth load sensors (Activ5 by Activbody and Progressor by Tindeq). Methods: Four tests were conducted on each device: stepped loading, stress relaxation, simulated exercise, and hysteresis. Each test type was repeated three times using the Instron ElectroPuls mechanical testing device (a gold-standard system). Test–retest reliability was assessed through intraclass correlations. Agreement with the gold standard was assessed with Pearson’s correlation, interclass correlation, and Lin’s concordance correlation. Results: The Activ5 and Progressor had excellent test–retest reliability across all four tests (ICC(3,1) ≥ 0.999, all p ≤ 0.001). Agreement with the gold standard was excellent for both the Activ5 (ρ ≥ 0.998, ICC(3,1) ≥ 0.971, ρc ≥ 0.971, all p’s ≤ 0.001) and Progressor (ρ ≥ 0.999, ICC(3,1) ≥ 0.999, ρc ≥ 0.999, all p’s ≤ 0.001). Measurement error increased for both devices as applied load increased. Conclusion: Excellent test–retest reliability was found, suggesting that both devices can be used in a clinical setting to measure patient progress over time; however, the Activ5 consistently had poorer agreement with the gold standard (particularly at higher loads).
Highlights
Introduction iationsDue to aging, injury, or a combination of the two, many people experience strength deficits at some point in their lifetime [1,2]
Strength deficits are apparent in a variety of conditions including osteoarthritis [3], stroke [4], and tendinopathy [5], to name a few
One data point was identified in one repetition of the stepped loading test for the Progressor, and one data point was identified in one repetition of the hysteresis test for the Progressor
Summary
Introduction iationsDue to aging, injury, or a combination of the two, many people experience strength deficits at some point in their lifetime [1,2]. Strength deficits are apparent in a variety of conditions including osteoarthritis [3], stroke [4], and tendinopathy [5], to name a few. Such deficits can result in mobility limitations [6,7] and may predict mortality [8], length of hospital stay [9], and hospital readmission rates [10]. Conservative management strategies (e.g., therapeutic exercise targeting mechanical tissue deficits) can lead to positive tissue adaptation and symptom alleviation in a variety of conditions [11,12].
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