An interventional study of usual care constant work rate bedcycling and Individualized constant work rate bedcycling in Critical Illness, sponsored by KU Leuven. Not yet recruiting. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-10-20.
Sponsored by KU Leuven · Not applicable, Interventional, and Treatment
### 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.
1,923 studies on the registry are indexed under Critical Illness; 465 are open to participants now.
This study's planned enrollment of 29 is below the median of 90 across 1,003 interventional studies indexed under Critical Illness.
Browse Critical Illness studies →KU Leuven is the lead sponsor of 371 studies on the registry; 63 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Inclusion criteria
Exclusion criteria MEDICAL STABILITY A. Hemodynamic instability
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
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
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.
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.
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.
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.
Time frame: During each bed-cycling session (Days 1-3; within a maximum of 5 days).
Quadriceps muscle fatigue (Median Frequency)
Muscle fatigue will be assessed by changes in the median frequency (Hz) of the surface electromyography signal over the four quadriceps regions during the incremental loading test and the three cycling protocols. A reduction in median frequency is considered indicative of muscle fatigue.
Time frame: During the incremental loading test and each cycling session (Days 0-3; within 5 days).
Quadriceps muscle fatigue (Frequency ratio)
Muscle fatigue will be assessed using changes in the high-frequency to low-frequency ratio of the sEMG signal across the four quadriceps regions during exercise.
Time frame: During the incremental loading test and each cycling session (Days 0-3; within 5 days).
Spatial heterogeneity of quadriceps muscle activation
Spatial heterogeneity of quadriceps muscle activation will be quantified as the relative dispersion of normalized sEMG amplitude across four quadriceps regions. Relative dispersion will be calculated as the standard deviation divided by the mean activation across the four regions.
Time frame: During the incremental loading test and each cycling session (Days 0-3; within 5 days).
Quadriceps muscle oxygenation
Local quadriceps muscle tissue oxygen saturation (StiO2, %) will be continuously assessed using near-infrared spectroscopy (NIRS) at four muscle regions: vastus lateralis, vastus medialis, upper rectus femoris, and lower rectus femoris. Resting values and oxygenation responses during exercise will be assessed across the cycling protocols.
Time frame: 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)
Near-infrared spectroscopy (NIRS) will be used to assess oxygenated hemoglobin/myoglobin signals in four quadriceps regions during exercise.
Time frame: 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 (deoxygenated)
Near-infrared spectroscopy (NIRS) will be used to assess deoxygenated hemoglobin/myoglobin signals in four quadriceps regions during exercise.
Time frame: 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 (total)
Near-infrared spectroscopy (NIRS) will be used to assess total hemoglobin/myoglobin signals in four quadriceps regions during exercise.
Time frame: At rest, during and immediately after the incremental loading test and each cycling session (Days 0-3; within 5 days).
Spatial Heterogeneity of Quadriceps Muscle Oxygenation
Spatial heterogeneity of muscle oxygenation will be quantified using the relative dispersion of NIRS-derived muscle tissue oxygen saturation (StiO2) across four quadriceps regions.
Time frame: At rest and during the incremental loading test and each cycling session (Days 0-3; within 5 days).
Changes in haert rate during Bed-Cycling
Hemodynamic responses will be assessed using changes in heart rate (beats/min), measured before, during and after exercise.
Time frame: Before, during and immediately after the incremental loading test and each cycling session (Days 0-3; within 5 days).
Changes in mean arterial blood pressure during Bed-Cycling
Hemodynamic responses will be assessed using changes in mean arterial blood pressure (mmHg), measured before, during and after exercise.
Time frame: Before, during and immediately after the incremental loading test and each cycling session (Days 0-3; within 5 days).
Changes in respiratory rate During Bed-Cycling
Respiratory responses will be assessed using changes in respiratory rate (breaths/min) before, during and after exercise.
Time frame: Before, during and immediately after the incremental loading test and each cycling session (Days 0-3; within 5 days).
Changes in peripheral oxygen saturation During Bed-Cycling
Respiratory responses will be assessed using changes in peripheral oxygen saturation (SpO2, %) before, during and after exercise.
Time frame: Before, during and immediately after the incremental loading test and each cycling session (Days 0-3; within 5 days).
Changes in fraction of inspired oxygen During Bed-Cycling
Respiratory responses will be assessed using changes in fraction of inspired oxygen (FiO2, %) before, during and after exercise.
Time frame: Before, during and immediately after the incremental loading test and each cycling session (Days 0-3; within 5 days).
Changes in Arterial Blood Gas (arterial oxygen partial pressure) During Bed-Cycling
arterial oxygen partial pressure (PaO2) obtained as part of routine clinical care will be assessed before and after exercise.
Time frame: Before and after the incremental loading test and each cycling session (Days 0-3; within 5 days).
Changes in Arterial Blood Gas (arterial carbon dioxide partial pressure) During Bed-Cycling
Arterial carbon dioxide partial pressure (PaCO2) obtained as part of routine clinical care will be assessed before and after exercise.
Time frame: Before and after the incremental loading test and each cycling session (Days 0-3; within 5 days).
Changes in Arterial Blood Gas (arterial oxygen saturation) During Bed-Cycling
arterial oxygen saturation (SaO2) obtained as part of routine clinical care will be assessed before and after exercise.
Time frame: Before and after the incremental loading test and each cycling session (Days 0-3; within 5 days).
Changes in Arterial Blood Gas (pH) During Bed-Cycling
pH obtained as part of routine clinical care will be assessed before and after exercise.
Time frame: Before and after the incremental loading test and each cycling session (Days 0-3; within 5 days).
Changes in Arterial Blood Gas (hemoglobin concentration) During Bed-Cycling
hemoglobin concentration obtained as part of routine clinical care will be assessed before and after exercise.
Time frame: Before and after the incremental loading test and each cycling session (Days 0-3; within 5 days).
Changes in Arterial Blood Gas (blood lactate concentration) During Bed-Cycling
blood lactate concentration obtained as part of routine clinical care will be assessed before and after exercise.
Time frame: Before and after the incremental loading test and each cycling session (Days 0-3; within 5 days).
Exercise-Related Safety Events and In-Session Stopping Criteria
The number and proportion of exercise sessions associated with predefined stopping criteria or exercise-related safety events will be recorded during cycling and within 10 minutes after exercise.
Time frame: During exercise and up to 10 minutes after each session (Days 0-3; within 5 days).
Proportion of Planned Bed-Cycling Sessions Initiated
Feasibility will be assessed as the percentage of planned individualized constant work-rate cycling (i-CWR) and individualized interval training (i-IT) sessions that can be initiated. The number of initiated sessions will be divided by the number of planned sessions and multiplied by 100.
Time frame: Across the individualized cycling sessions (Days 0-3; within 5 days).
Proportion of Initiated Bed-Cycling Sessions Completed
Feasibility will be assessed as the percentage of initiated individualized cycling sessions completed according to protocol. The number of completed sessions will be divided by the number of initiated sessions and multiplied by 100. Reasons for premature termination and protocol deviations will be recorded.
Time frame: Across the individualized cycling sessions (Days 0-3; within 5 days).
Self-Reported Dyspnea During Bed-Cycling
Dyspnea will be assessed using a modified Borg scale ranging from 0 (no dyspnea) to 10 (maximal dyspnea), at baseline, after each completed minute of exercise, and at the end of each session.
Time frame: Before, during and immediately after the incremental loading test and each cycling session (Days 0-3; within 5 days).
Self-Reported Leg Fatigue During Bed-Cycling
Perceived leg fatigue will be assessed using a modified Borg scale ranging from 0 (no leg fatigue) to 10 (maximal leg fatigue), at baseline, after each completed minute of exercise, and at the end of each session.
Time frame: Before, during and immediately after the incremental loading test and each cycling session (Days 0-3; within 5 days).
Self-Reported Exercise Unpleasantness
Exercise-related unpleasantness will be assessed using a modified Borg scale ranging from 0 to 10, with higher scores indicating greater unpleasantness, at baseline, after each completed minute of exercise, and at the end of each session.
Time frame: Before, during and immediately after the incremental loading test and each cycling session (Days 0-3; within 5 days).
Cycling Exercise Performance: resistance level
Cycling performance will be characterized by resistance level (level 0 - 20) during the incremental loading test and cycling sessions.
Time frame: During the incremental loading test and cycling sessions (Days 0-3; within 5 days).
Cycling Exercise Performance: cycling distance
Cycling performance will be characterized by cycling distance (m) during the incremental loading test and cycling sessions.
Time frame: During the incremental loading test and cycling sessions (Days 0-3; within 5 days).
Cycling Exercise Performance: cadence
Cycling performance will be characterized by cadence (revolution/min) during the incremental loading test and cycling sessions.
Time frame: During the incremental loading test and cycling sessions (Days 0-3; within 5 days).
Cycling Exercise Performance: duration of active cycling
Cycling performance will be characterized by duration of active cycling (minutes) during the incremental loading test and cycling sessions.
Time frame: During the incremental loading test and cycling sessions (Days 0-3; within 5 days).
Cycling Exercise Performance: duration of passive cycling
Cycling performance will be characterized by duration of passive cycling (minutes) during the incremental loading test and cycling sessions.
Time frame: During the incremental loading test and cycling sessions (Days 0-3; within 5 days).
Cycling Exercise Performance: average power output
Cycling performance will be characterized by average power output (W) during the incremental loading test and cycling sessions.
Time frame: During the incremental loading test and cycling sessions (Days 0-3; within 5 days).
No study locations are listed for this record.
Plan to share: No
No publications or documents are linked to this record.
Start is estimated for Nov 2026; primary completion for May 2027, 6 months later.
Of 422 non-industry interventional studies with no phase under Critical Illness, half reached primary completion within 21 months of starting (the median), counting those still running; a quarter within 11 and three quarters within 38. This study's planned 6 months is below that.
Counting every sponsor, half of 427 studies reached it within 21 months; a quarter within 11 and three quarters within 37.
Critical Illness covers many different conditions, not one, so the studies compared here vary widely. Read these figures as a rough guide.
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From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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