"suMus," a novel digital system for arm movement metrics and muscle energy expenditure

Teresa Gerhalter; Christina Müller; Elke Maron; Markus Thielen; Teresa Schätzl; Anja Mähler; Till Schütte; Michael Boschmann; René Herzer; Simone Spuler; Elisabetta Gazzerro

doi:10.3389/fphys.2023.1057592

"suMus," a novel digital system for arm movement metrics and muscle energy expenditure

Front Physiol. 2023 Jan 26:14:1057592. doi: 10.3389/fphys.2023.1057592. eCollection 2023.

Authors

Teresa Gerhalter^{1

2

3}, Christina Müller⁴, Elke Maron⁵, Markus Thielen⁴, Teresa Schätzl^{1

2

3}, Anja Mähler^{2

3

6}, Till Schütte^{2

3

6

7}, Michael Boschmann^{2

3

6}, René Herzer⁴, Simone Spuler^{1

2

3

6}, Elisabetta Gazzerro^{1

2

3

6}

Affiliations

¹ Muscle Research Unit, Charité-Universitätsmedizin Berlin, Berlin, Germany.
² Experimental and Clinical Research Center, a joint Cooperation between the Max Delbrück Center for Molecular Medicine in the Helmholtz Association and the Charité-Universitätsmedizin Berlin, Berlin, Germany.
³ Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany.
⁴ Basebox.Health, Utting, Germany.
⁵ ElanPhysio, Berlin, Germany.
⁶ Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany.
⁷ Clinical Study Center (CSC), Berlin Institute of Health at Charité-Universitätsmedizin Berlin, Berlin, Germany.

Abstract

Objective: In the field of non-treatable muscular dystrophies, promising new gene and cell therapies are being developed and are entering clinical trials. Objective assessment of therapeutic effects on motor function is mandatory for economical and ethical reasons. Main shortcomings of existing measurements are discontinuous data collection in artificial settings as well as a major focus on walking, neglecting the importance of hand and arm movements for patients' independence. We aimed to create a digital tool to measure muscle function with an emphasis on upper limb motility. Methods: suMus provides a custom-made App running on smartwatches. Movement data are sent to the backend of a suMus web-based platform, from which they can be extracted as CSV data. Fifty patients with neuromuscular diseases assessed the pool of suMus activities in a first orientation phase. suMus performance was hence validated in four upper extremity exercises based on the feedback of the orientation phase. We monitored the arm metrics in a cohort of healthy volunteers using the suMus application, while completing each exercise at low frequency in a metabolic chamber. Collected movement data encompassed average acceleration, rotation rate as well as activity counts. Spearman rank tests correlated movement data with energy expenditure from the metabolic chamber. Results: Our novel application "suMus," sum of muscle activity, collects muscle movement data plus Patient-Related-Outcome-Measures, sends real-time feedback to patients and caregivers and provides, while ensuring data protection, a long-term follow-up of disease course. The application was well received from the patients during the orientation phase. In our pilot study, energy expenditure did not differ between overnight fasted and non-fasted participants. Acceleration ranged from 1.7 ± 0.7 to 3.2 ± 0.5 m/sec² with rotation rates between 0.9 ± 0.5 and 2.0 ± 3.4 rad/sec. Acceleration and rotation rate as well as derived activity counts correlated with energy expenditure values measured in the metabolic chamber for one exercise (r = 0.58, p < 0.03). Conclusion: In the analysis of slow frequency movements of upper extremities, the integration of the suMus application with smartwatch sensors characterized motion parameters, thus supporting a use in clinical trial outcome measures. Alternative methodologies need to complement indirect calorimetry in validating accelerometer-derived energy expenditure data.

Keywords: accelerometers; apple watch; energy expenditure; inertial sensors; muscular dystrophies; neuromuscular diseases; outcome measures; smartwatch.

Grants and funding

The concept of the suMus application was developed in the context of the “BIH Digital Accelerator Program 2019” at the Berlin Institut of Health, Berlin Germany. The present study was sponsored by Roche Pharmaceuticals, Basel, Switzerland. The funder was not involved in the study design, collection, analysis, interpretation of data, the writing of this article or the decision to submit it for publication.