Quadriceps Muscle Activation and Oxygenation Responses During Usual Care Compared to Individualized Interval and Constant Work Rate Bed-cycling. An Experimental Study.

NCT07882719 | Not Yet Recruiting

• 1 other identifier: S72226
• Study Type: interventional
• Target: 29
• Locations: 0 countries
• Sites: N/A

Brief 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.

Conditions

Critical Illness

Keywords

critical illness; early mobilisation; rehabilitation; cycling

Outcome Measures

Primary Outcomes (1)

• Average Quadriceps Muscle Activation During Bed-Cycling

  Average quadriceps muscle activation will be assessed using surface electromyography (sEMG) during the cycling protocols (u-CWR, i-CWR and i-IT). Activation will be expressed as normalized root mean square (RMS) amplitude relative to maximal voluntary contraction (%max), averaged across four quadriceps regions: vastus lateralis, vastus medialis, upper rectus femoris, and lower rectus femoris.

  During each bed-cycling session (Days 1-3; within a maximum of 5 days).

Secondary Outcomes (25)

• Quadriceps muscle fatigue (Median Frequency)

  During the incremental loading test and each cycling session (Days 0-3; within 5 days).

• Quadriceps muscle fatigue (Frequency ratio)

  During the incremental loading test and each cycling session (Days 0-3; within 5 days).

• Spatial heterogeneity of quadriceps muscle activation

  During the incremental loading test and each cycling session (Days 0-3; within 5 days).

• Quadriceps muscle oxygenation

  At rest, during and immediately after the incremental loading test and each cycling session (Days 0-3; within 5 days).

• Quadriceps muscle hemoglobine and Myoglobine Responses (oxygenated)

  At rest, during and immediately after the incremental loading test and each cycling session (Days 0-3; within 5 days).

Other Outcomes (6)

• Cycling Exercise Performance: resistance level

  During the incremental loading test and cycling sessions (Days 0-3; within 5 days).

• Cycling Exercise Performance: cycling distance

  During the incremental loading test and cycling sessions (Days 0-3; within 5 days).

• Cycling Exercise Performance: cadence

  During the incremental loading test and cycling sessions (Days 0-3; within 5 days).

Study Arms (2)

i-CWR / i-IT

EXPERIMENTAL

Individualized continuous work-rate cycling (i-CWR) will be provided on day 2, followed by the individualized interval training (i-IT) on day 3. Both individualized cycling modalities will be prescribed based on the results of the incremental loading test performed on day 1

Other: usual care constant work rate bedcycling; Other: Individualized constant work rate bedcycling; Other: Individualized interval bedcycling

i-IT / i-CWR

EXPERIMENTAL

Individualized interval training (i-IT) will be provided on day 2, followed by the individualized continuous work-rate cycling (i-CWR) on day 3. Both individualized cycling modalities will be prescribed based on the results of the incremental loading test performed on day 1

Other: usual care constant work rate bedcycling; Other: Individualized constant work rate bedcycling; Other: Individualized interval bedcycling

Interventions

Individualized interval bedcycling OTHER

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.

i-CWR / i-IT; i-IT / i-CWR

usual care constant work rate bedcycling OTHER

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.

i-CWR / i-IT; i-IT / i-CWR

Individualized constant work rate bedcycling OTHER

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.

i-CWR / i-IT; i-IT / i-CWR

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Voluntary written informed consent of the participant has been obtained prior to the initiation of any study-related measurements
• Adults (≥18 years)
• Mechanically ventilated for ≥ 48 hours consecutively
• Fully cooperative, as assessed daily during routine clinical care by ICU physiotherapists using five standardized commands ("open/close your eyes", "look at me", "open your mouth and stick out your tongue", "nod your head", and "raise your eyebrows when I have counted to 5").
• Able to perform active cycling for \>10 consecutive minutes
• Expected to remain in the ICU for more than an additional 4 days starting from study enrolment.

You may not qualify if:

• Evidence of acute coronary ischemia
• Heart rate \<40 or \>120 beats per minute
• Mean arterial pressure \<60 or \>110 mmHg
• Noradrenaline or comparable inotropic or vasopressor support (norepinephrine \>0.2ug/kg/min, dobutamine \>5ug/kg/min, corotrope \>0.2 ug/kg/min) B. Respiratory instability
• Fraction of inspired oxygen ≥ 60%
• PaO₂/FiO₂ ratio \< 200
• Positive end-expiratory pressure \> 10 cmH2O
• Respiratory rate \> 30 breaths·min-¹ C. Surgery within the past 24h D. Body temperature \> 40 oC CONDITIONS IMPAIRING CYCLING MOVEMENT
• Trauma or surgery to lower limb, pelvis lumbar spine
• Extreme obesity (body mass index \>35 kg/m2)
• Extensive abdominal wounds or pressure ulcers
• Continuous renal replacement therapy by CVVH-femoral catheter PALIATIVE CARE

Sponsors & Collaborators

• KU Leuven: lead

MeSH Terms

Conditions

Critical Illness

Condition Hierarchy (Ancestors)

Disease Attributes; Pathologic Processes; Pathological Conditions, Signs and Symptoms

Central Study Contacts

Langer Daniel

CONTACT

+32 16 34 71 25; daniel.langer@kuleuven.be

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Associate professor Faculty of Movement and Rehabilitation Sciences

Study Record Dates

• First Submitted: October 13, 2026
• First Posted: October 20, 2026
• Study Start (Estimated): November 1, 2026
• Primary Completion (Estimated): May 1, 2027
• Study Completion (Estimated): May 1, 2027
• Last Updated: October 20, 2026

Record last verified: 2026-10

Data Sharing

• IPD Sharing: Will not share