Summary by Molly Stark

Publication

Evaluation of a control paradigm allowing heart rate guided rehabilitative exercise for boys with Duchenne muscular dystrophy

Kimberly Stubbs, Meghana Bomma, Donovan J. Lott, Emily Griffis, Hannah M. Sweatland, Wanjiku A. Makumi, John-Anthony Coppola, Renata Shih, H. L. Sweeney, Warren Dixon, and Tanja Taivassalo

Journal of NeuroEngineering and Rehabilitation

Dec 2025

https://pubmed.ncbi.nlm.nih.gov/41466412/

As the evidence base for exercise prescription in Duchenne muscular dystrophy (DMD) continues to evolve, it is important to explore safe, feasible, and quantifiable intensity targets for aerobic activity. Stubbs and Bomma et al. evaluate a heart-rate (HR)-guided, motor-assisted cycling paradigm intended to support moderate-intensity aerobic exercise in ambulatory boys with DMD. The system enables clinicians to adjust the optimal “dose” in real time under remote supervision based on the participant’s HR.

The authors aim to demonstrate the feasibility of a motor-assisted cycling paradigm that uses HR reserve (HRR) to individualise intensity, with a target zone of approximately 40-50% HRR. They also verified participants’ ability to produce measurable power, rather than purely passive cycling, with the assistance of the motor. The system incorporates a controller that adjusts the motor to maintain cadence within predefined bounds, and instrumented pedals to estimate passive vs active power, providing an objective measurement to accompany physiological intensity monitoring.

In a pilot dataset of six ambulatory boys aged six to nine years, with genetically confirmed DMD, participants completed short cycling bouts (3-10 minutes). The mean assistive current was 0.53 ± 0.15 A (range 0.3-0.8 A). HR increased progressively from rest through a passive warm-up minute and then active cycling, reaching the prescribed moderate-intensity window (45% HRR during active cycling). The authors also report average cycling power of 5.7 ± 1.3 W with expected between-participant variability (range 3-8 W), consistent with differences in functional capacity across individuals.

Collectively, the authors report that the assisted cycling paradigm is well tolerated in this proof-of-concept implementation, with no exercise-related adverse events observed during the sessions. Furthermore, the combined HRR target and the monitoring of participant-generated power provide a coherent framework for remote dosing and verification of effort. They conclude that this approach supports subsequent studies designed to test longer-term training effects, refine automation of the assisted cycling paradigm, and ultimately establish clinically relevant aerobic exercise dose parameters for rehabilitation with individuals with DMD and other neuromuscular disorders.

About the authors

Kimberly Stubbs, PhD (first co-author): Dr Kimberly Stubbs is affiliated with the University of Florida within the Department of Mechanical and Aerospace Engineering as an Instructional Assistant Professor. She received her PhD in mechanical engineering from the University of Florida. Dr Stubbs currently teaches and supervises undergraduate students in the MATLAB coding environment. She is also a faculty mentor of an Integrated Product and Process Design team. Her research centres on rehabilitation robotics, human-machine interaction, and nonlinear control.

Meghana Bomma, BSc (first co-author): Meghana Bomma is currently a second-year medical student at Florida State University. For her work on this research study, she is affiliated with the Department of Physiology and Ageing at the University of Florida. Prior to starting medical school, Meghana was involved in DMD research, particularly related to cardiopulmonary exercise testing and physiological limitations in DMD.

About the reviewer

Molly Stark, DPT: Molly Stark is a physical therapist and clinical evaluator at the Greg Marzolf Jr. Muscular Dystrophy Center at the University of Minnesota. She received her Doctorate of Physical Therapy degree from the University of Wisconsin – La Crosse in 2013. Molly’s clinical work focuses on neuromuscular disease in the paediatric population. Molly is also a clinical evaluator and is involved in a variety of clinical trials and research studies for individuals with neuromuscular diseases.