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Quadriceps Muscle Activation and Oxygenation Responses During Usual Care Compared to Individualized Interval and Constant Work Rate Bed-cycling. An Experimental Study.
Sponsor: KU Leuven
Summary
\### Study Summary - AcuteBike-ICU Bed-cycling is commonly used as part of early rehabilitation in critically ill patients in the intensive care unit (ICU). However, the extent to which usual care bed-cycling activates the quadriceps muscles remains unclear, as does whether individualized exercise protocols can increase muscle stimulation. The AcuteBike-ICU study is an experimental study aiming to compare the acute physiological responses to three bed-cycling protocols in critically ill patients: usual care constant work-rate cycling (u-CWR), individualized constant work-rate cycling (i-CWR), and individualized interval training (i-IT). A total of 29 critically ill patients admitted to medical or surgical ICUs will be included. Participants will undergo an incremental loading test to determine their individual exercise capacity, followed by the different cycling protocols. The individualized continuous protocol involves cycling against a moderate resistance, whereas interval training alternates short periods of high-intensity cycling with passive cycling. The primary outcome is quadriceps muscle activation, assessed using surface electromyography (sEMG) across four quadriceps muscle regions. Secondary outcomes include muscle fatigue, activation heterogeneity, muscle oxygenation and metabolism assessed using near-infrared spectroscopy (NIRS), as well as safety, feasibility, and patient-reported symptoms. Retrospective data from routine bed-cycling sessions will also be analyzed to characterize current clinical practice. Each participant will complete the study within a maximum of five days. By identifying which cycling protocol elicits the greatest quadriceps muscle stimulation, this study aims to support the development of more individualized and potentially more effective early rehabilitation strategies for critically ill patients.
Key Details
Gender
All
Age Range
18 Years - Any
Study Type
INTERVENTIONAL
Enrollment
29
Start Date
2026-11
Completion Date
2027-05
Last Updated
2026-10-20
Healthy Volunteers
No
Conditions
Interventions
usual care constant work rate bedcycling
Participants will perform a usual care cycling session using the bed cycle according to routine clinical practice. The training intensity will be determined by the treating physiotherapist, without knowledge of the maximal exercise capacity. The cycling session will last for a maximum of 20 minutes.
Individualized constant work rate bedcycling
patients will perform continuous active cycling at 50% of maximal exercise capacity. Patients will remain in the same body position as during the other cycling protocols and the cycling duration of the 2 individualized cycling protocols (i-CWR and i-IT) will be matched with a maximal duration of 20 minutes.
Individualized interval bedcycling
Patients will perform interval cycling with alternating 30-second periods of active cycling at 100% of the maximal tolerated intensity level and 30-second periods of motor-assisted passive cycling without resistance. Patients will remain in the same body position as during the other cycling protocols and the cycling duration of the 2 individualized cycling protocols (i-CWR and i-IT) will be matched with a maximal duration of 20 minutes.