Method Article

Implementing In-bed Cycle Ergometry for Mechanically Ventilated Patients using the Rehabilitation Treatment Specification System

July 7th, 2026

 ,  ,  ,  ,  , 
1Department of Physiotherapy, Austin Health, 2Department of Physiotherapy, The University of Melbourne, 3Institute for Breathing and Sleep, 4School of Rehabilitation Science, McMaster University, 5Niagara Knowledge Institute, 6Department of Physiotherapy, Ipswich Hospital, West Moreton Health, 7Research Institute of St. Joe's Hamilton

In This Article

Summary

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Protocols for the delivery of in-bed leg cycle ergometry to critically ill patients in the intensive care unit are presented according to the Rehabilitation Treatment Specification System to promote standardization of procedures, ensure patient safety, and support reproducibility across clinical and research settings.

Abstract

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In-bed cycle ergometry is a safe, feasible, and reliable method of providing in-bed physical rehabilitation for patients with critical illness in the intensive care unit. It is a complex intervention that requires specific clinical decision-making skills to identify suitable patients, close coordination with the team to deliver the intervention, and ongoing evaluation to guide treatment progression. Protocols for the delivery of in-bed cycle ergometry are presented according to the Rehabilitation Treatment Specification System. Specifically, the components of in-bed leg cycle ergometry are described, including preparation, equipment, therapist actions (instructions and feedback), progression considerations, and clinical decision-making.

Patient selection for in-bed cycle ergometry in the intensive care unit should prioritize physiological stability, with safety criteria for starting and stopping, and defined inclusion and exclusion criteria to support standardized and reproducible delivery. The patient should be in the semi-recumbent position, with the in-bed cycle ergometer secured at the foot of the bed and neutral lower limb alignment maintained. Dosing and progression should consider active or passive modes, frequency, duration, cadence, and resistance. Patient monitoring should include clearly specified physiological and tolerance thresholds, with increases applied systematically. Documentation of treatments following the Rehabilitation Treatment Specification System supports clinical decision-making, standardization, and reproducibility.

Introduction

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Physical disability is often a severe and long-lasting consequence of critical illness1,2. Advances in intensive care medicine have improved survival rates over the last 30 years3. However, there is emerging recognition of the impact of physical impairments experienced by survivors following discharge from the intensive care unit (ICU)4. Long-term physical impairments originate from ICU-acquired weakness (ICU-AW), a global, symmetrical neuromuscular weakness related to the ICU admission alone5. Factors contributing to the development of ICU-AW include prolonged bed rest and systemic inflammation, resulting in a net catabolic state, which leads to accelerated muscle atrophy6,7. Losses of up to 20% of skeletal muscle mass have been reported in the first ten days of ICU admission. Further, the development of ICU-AW increases the risk of death, prolonged mechanical ventilation and protracted admissions in ICU and hospital8.

Rehabilitation of patients with critical illness commences in the ICU environment and typically includes exercise therapy and progressive functional mobility9. When rehabilitation begins in the ICU, it is associated with improved physical function at hospital discharge and reduced length of stay in both the ICU and hospital settings10,11. However, early initiation of rehabilitation is conditional on haemodynamic and metabolic stability12. In-bed cycle ergometry has emerged as a novel approach of providing in-bed exercise to patients with critical illness13,14. In-bed cycle ergometry may be applied to either the upper or lower limbs15,16. Importantly, in-bed cycle ergometry is safe17,18, feasible and an acceptable therapy for patients with critical illness19, which may improve physical function at ICU discharge and beyond15.

However, in-bed cycle ergometry is a complex rehabilitation intervention that lacks published guidance on practical implementation, particularly for patients undergoing mechanical ventilation in the ICU. In-bed cycle ergometry can be delivered in different modes depending on the patient’s condition and level of participation20. First, the intervention may be delivered passively, where the motor drives the pedals, which move the patients’ legs without voluntary effort19. Second, it may be performed actively, where the patient contributes to the movement of the pedals with or without assistance from the motor19. Third, in the setting of active participation, resistance may be added to provide a greater training stimulus in those able to tolerate this19.

Therefore, we aim to provide a structured, reproducible protocol for in-bed leg-cycle ergometry of the lower limbs21. Specifically, we will outline the processes for the preparation of the patient, equipment, therapist actions, including instructions and feedback, progression considerations, and clinical decision-making for in-bed cycle ergometry. This protocol is based on evidence from a recently published randomized controlled trial18 and systematic reviews and meta-analyses15,22.

Introduction to the Rehabilitation Treatment Specification System
The Rehabilitation Treatment Specification System (RTSS) was developed by a multidisciplinary team of rehabilitation specialists to provide a structured and rigorous framework for defining, classifying, and measuring rehabilitation treatments21. Its development was prompted by a lack of detailed description of rehabilitation treatment methods in both research23 and clinical practice24. Reporting guidelines describe study conduct (e.g., CONSORT25), individual components of interventions (e.g., TIDier; template for intervention description and intervention26 and CERT; Consensus on Exercise Reporting Template27), and frameworks like the International Classification of Function (ICF28), which classify overall goals of treatment (e.g., walking). However, these systems focus on who and what of rehabilitation. Rehabilitation treatments are frequently described solely in terms of service duration (e.g., minutes of physiotherapy intervention) or the specific problems they aim to treat (e.g., mobility training), or the care setting (e.g., ICU).

What existing frameworks do not describe is the how of rehabilitation—what the clinician does or provides to a patient in a therapy session to achieve a specific change in patient function. The RTSS is intended to organize treatments according to the change in function that the clinician and treatment recipient hope to achieve in a session, which is the target of intervention; the ingredients (what the clinician provides or does that is hypothesized to effect that change in function); and the mechanisms of action by which the clinician hypothesizes the ingredients have their effects29. Treatment targets must be measurable, and are categorized into three groups: Organ Functions, Skills and Habits, and Representations (changes in thinking or feeling)23. Changes in organ function can be achieved passively, for example, through limb passive range of motion with the treatment target of maintaining existing joint range of motion and preventing contractures; or actively, through limb active range of motion with the application of graded resistance, with the treatment target of increasing muscle strength. For both Skills and Habits and Representation targets, the treatment recipient is an active participant.

The RTSS has been applied to physical rehabilitation of children and adults30,31,32,33,34,35,36,37, and there are guidelines for embedding it into standard clinical care38 (Figure 1).  Here, we will apply the RTSS to in-bed cycle ergometry with critically ill patients, describing the intervention according to its targets, hypothesized mechanisms of action, and ingredients.

Protocol

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All procedures included within this protocol reflect primary studies that adhered to local institutional ethical standards and guidelines. No specific ethical approval was required for this protocol article.

1. Patient selection and presession assessment

  1. Identify patients appropriate for in-bed cycle ergometry, considering all contraindications and precautions (Table 1).
  2. Perform a multi-system assessment to determine the patients’ neurological status, haemodynamic stability, respiratory stability, and functional ability.
  3. Use findings to determine starting mode, duration, cadence, and resistance.
  4. Screen, review, and document any preexisting pressure injuries, ensuring that it is safe to proceed with therapy.
  5. Coordinate timing of therapy with the ICU multidisciplinary team.

2. Equipment preparation

  1. Review all lines and attachments to the patient and secure them away from moving components of the cycle ergometer.
  2. Remove the foot of the bed if required.
  3. Position the in-bed cycle ergometer aligned with the patient’s midline.
  4. Secure the in-bed cycle ergometer to the bed and apply brakes (model dependent).

3. Patient positioning

  1. Maintain patient dignity (e.g., towel covering pelvic region).
  2. Position the patient semi-recumbent in supine with the head elevated and pelvis level.
  3. Place feet on pedals and secure with straps.
  4. Provide additional padding as required (e.g., using towels) to protect the skin whilst in the leg shells.
  5. Confirm alignment by completing one full pedal revolution, specifically avoiding knee hyper-extension (allow approximately 15° of knee flexion) or excessive hip flexion (greater than 100°).
  6. Re-check all securing mechanisms (brakes and attachments to the bed).

4. Therapy prescription

  1. Prescribe therapy according to options available on the model of in-bed cycle ergometer in use.
  2. Select initial therapy mode from: Passive, Active-assisted/Active, or Resisted (Passive if patient unable to participate, Active if able to participate, Resisted if easily able to participate).
  3. Select duration of warm up (range 2–5 min, typically 2 min), main therapy (range 10–60 min, typically 30 min but as tolerated), and cool down (range 2–5 min, typically 2 min).
  4. Select target rate per minute (range 5–30 RPM, minimum 5 RPM).
  5. Adjust the resistance for patients by beginning with a low resistance of less than 0.6 Nm and increasing in increments of 1 to 5 watts Nm in response to the patient’s tolerance.

5. Patient monitoring during therapy

  1. Commence therapy once therapy prescription has been completed and checked.
  2. Monitor observations and vital signs for breaches of stopping criteria throughout the session.
  3. Monitor lines and attachments.
  4. Monitor patient interaction.
  5. Adjust therapy according to patient interaction and/or any changes in observations and vital signs.

6. Progression criteria

  1. Encourage the patient using verbal cues.
  2. Evaluate patient participation in therapy.
  3. Progress one variable at a time if able (duration first, then resistance).
    1. Increase rate if participation is limited. Decrease rate if patient participation is increasing.
    2. Adjust duration of session based on tolerance.

7. Termination criteria

  1. Immediately cease activity if stopping criteria are met (Table 2). Remove the patient’s feet from pedals. Reassess vital signs immediately and notify the ICU team if instability persists.
  2. Otherwise terminate session once desired duration has been reached or the patient elects to cease the session.
  3. Stop therapy and ensure the in-bed cycle ergometer has ceased movement.
  4. Remove feet from pedals.
  5. Remove all securing devices.
  6. Release brakes.
  7. Remove the in-bed cycle ergometer.
  8. Clean the cycle ergometer in accordance with local policy for shared patient equipment.

8. Postsession procedures

  1. Review the patient for the presence of any new pressure or shear injuries. If present, document and inform the team.
  2. Reassess observations and vital signs.
  3. Evaluate patient participation in therapy. Adjust therapy prescription for future sessions.
  4. Document session details in the medical record.
  5. Communicate outcomes with the multidisciplinary team.

Results

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Successful implementation of this protocol of in-bed cycle ergometry will result in a completed physical rehabilitation session of in-bed cycle ergometry that is safe and without adverse events. Typical sessions may commence passively whilst a patient is sedated, unconscious, and unable to participate. The cadence will commence slowly (e.g., 5 RPM) and increase up to 30 RPM, or the patient’s self-selected pace. The duration of sessions will increase over time up to a total of 60 minutes as tolerance increases. Passive sessions will progress to active and then have resistance added if the patient is able to easily maintain up to 30 RPM independently. Expected changes in vital signs during therapy consist of those anticipated in response to exercise39. Specifically, these include transient increases in heart rate and respiratory rate39. Sessions that require early termination include those in which pre-defined safety criteria are breached or the patient indicates the session should be terminated (e.g., due to fatigue).

In-bed cycle ergometry has been safely and reliably delivered in clinical trials. Adverse events are uncommon, with a pooled rate of 1% (95% CI, 0 to 3%) across 17 trials and 904 patients and 1% (95% CI, 0 to 2%) across sessions from 11 trials and 4,623 sessions15. In the CYCLE RCT, in-bed cycle ergometry occurred in 92% of randomized patients for a median of 3 days (interquartile range, 2 to 5 days), within a median of 2 days (interquartile range, 2 to 4 days) of starting invasive mechanical ventilation18.

Treatment process diagram; mechanism of action, target, aim specification; causal relationship.
Figure 1: Overview of the Rehabilitation Treatment Specification System. This figure outlines the relationship between ingredient(s), mechanism(s) of action, target, and aim. The arrow above represents the direction of causality, whilst the arrow below represents the process of treatment specification. Each aim is addressed by one or more targets, and ingredients do not directly affect aims. The mechanism of action describes how the ingredient is hypothesized to affect the target. Figure adapted from Van Stan et al.23. Please click here to view a larger version of this figure.

Leg exercise therapy diagram; stages from passive to active; muscle activation, strength, endurance.
Figure 2: Application of the Rehabilitation Treatment Specification System to in-bed cycle ergometry. This figure provides an overview of exemplar targets, hypothesized mechanisms of action, ingredients, and measures quantifying targets for in-bed cycle ergometry. A continuum of non-volitional to fully volitional activities is highlighted, corresponding to passive, active-assisted, and active cycle ergometer therapies. Dotted lines with arrows refer to ingredients or measures provided across treatment sessions. For example, an in-bed cycle ergometer with a motor is required for non-volitional, partially volitional, and fully volitional treatment sessions. Figure adapted from Van Stan et al.23,40. Please click here to view a larger version of this figure.

SystemCriteria
CardiacNew cardiac instability
New unstable arrythmia with blood pressure compromise
New active, uncontrolled bleeding 
Escalating or high level vasopressor or inotrope dose within last two hours
Active myocardial ischaemia (New chest pain, ECG changes)
Mean Arterial Pressure (MAP) outside target range (< 60 or > 110 mmHg) within the last 2 h
Heart rate < 40 or > 140 bpm within the last 2 h
RespiratoryPersistent SpO2 < 88% within the last 2 h
FiO2 > 0.8 
Requirement for prone positioning  
NeurologicalSevere agitation which will impede cycling (Richmond Agitation and Sedation Scale > 2 within last 2 h) 
Neuromuscular blocker within last 4 h
OtherNew uncontrolled pain
Unstable lower limb fracture
Unstable spinal fracture 
Change in goals of care to palliative
Incision or wound which impedes cycling (e.g. open leg wound) 
Femoral access line which is compromised if hip is flexed to 90 degrees* 
Evidence of acute or worsening rhabdomyolysis
New clinical team concern 

Table 1: Contraindications to commencing in-bed cycle ergometry. In-bed cycle ergometry should not occur if one or more of the following conditions are present.
Precautions: If the patient has a femoral vascular access catheter, discuss suitability for in-bed cycle ergometry prior to commencing. Assess passive movement of the hip and knee prior to commencing in-bed cycle ergometry to determine whether the line is compromised on flexion. Femoral vascular access, includes central venous access devices, vascular catheters (for renal replacement therapy or dialysis), intra-aortic balloon pump (IABP), arterial line, or extracorporeal membrane oxygenation (ECMO).

SystemCriteria
CardiacCardiac arrest 
Sustained heart rate < 40 or > 140 bpm
MAP < 60 mm Hg (or below target MAP) or > 120 mm Hg
Systolic blood pressure > 200 mmHg
Patient requires > 30 µg/min of noradrenaline or equivalent
New unstable arrythmia
New evidence of myocardial ischaemia (New chest pain, ECG changes)  
RespiratoryUnplanned extubation 
Desaturation with SpO2 < 88% (or 10% below resting level) for more than 1 min
Respiratory rate > 35 breaths/min for more than 1 min
NeurologicalNew severe agitation  
OtherIntravascular catheter dislodgement or dysfunction 
Distress
Patient requests to stop due to feeling unwell 

Table 2: Criteria to cease in-bed cycle ergometry. In-bed cycle ergometry should be ceased if any of the following criteria are met.

Discussion

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In-bed cycle ergometry is a safe, feasible, and reliable therapy option for patients mechanically ventilated in the ICU that improves physical function by ICU and hospital discharge15.

Applying the RTSS to in-bed cycle ergometry
Figure 2 summarizes examples of targets, mechanisms of action, ingredients, and potential measures for in-bed cycle ergometry. We developed our approach to implementing in-bed cycle ergometry based on details reported in the primary studies summarized in a systematic review15. As an intervention, in-bed cycle ergometry increases physical activity through passive, active, or resisted lower limb movements.

Targets of treatment
In-bed cycle ergometry in mechanically ventilated patients is primarily designed to target Organ Function. These targets could include increasing leg muscle activation, increasing leg muscle strength, increasing leg muscle endurance, or increasing joint range of motion. Example measures to quantify Organ Function treatment targets include measures of muscle activation on palpation (target: increased leg muscle activation), power output in Watts (target: increased leg muscle strength), and duration of cycle motor support (target: increase leg muscle endurance). In-bed cycle ergometry also includes Skill and Habit targets, such as increased ability to cycle independently or increased consistency of participation in the in-bed cycle ergometry session. Taken together, these targets work towards the overall aim of improving patients’ physical function.

Mechanisms of action—How treatments affect targets
The adverse effects of prolonged bed rest are well established41. Generally, the cohort of patients mechanically ventilated with critical illness performs little to no physical activity42,43. Patients may be sedated whilst mechanically ventilated, and have limited ability to actively participate in a session. Previous studies demonstrated leg muscle activation in sedated patients with a Richmond Agitation and Sedation Scale Score of -3 (moderate sedation) or -4 (deep sedation)44. These actions can increase physical activity and recruit muscle fibre units to preserve or maintain muscle mass and therefore muscle strength. Thus, in-bed cycle ergometry is an example of an intervention that can be used as either a non-volitional intervention in sedated or unconscious patients or a fully volitional intervention in awake and cooperative patients19.

For in-bed cycle ergometry, our hypothesized mechanisms are primarily related to neuromuscular activation of the lower limbs45. For non-volitional or passive in-bed cycle ergometry, the bike supports the neuromuscular system. We hypothesize that repeated limb movement generated by motor support from the bike provides afferent and efferent neurological stimulation to activate central pattern generators46. Once a patient can participate volitionally in active-assisted or active in-bed cycle ergometry, requiring less support from the cycle motor, our hypothesized mechanism of action is challenging the leg muscles.

Treatment ingredients—What the therapist does or provides
We assume that all clinicians will offer good clinical practice, including introducing themselves and explaining the intervention to the patient, regardless of sedation status. It is not necessary to specify ingredients that are part of good clinical practice, unless they are essential for that treatment target.

Before commencing in-bed cycle ergometry, the clinician identifies the appropriate patient, ensures that appropriate safety factors for in-bed cycle ergometry have been checked and considered, and coordinates the therapy with the multidisciplinary ICU team to find a suitable time. In-bed cycle ergometry is intended to reduce the impact of post-ICU physical impairments15. Therefore, patient selection for in-bed cycle ergometry should focus on patients most at risk of ICU-acquired weakness and subsequent long-term physical disability47. These typically include but are not limited to patients with acute respiratory distress syndrome (ARDS) or acute respiratory failure currently receiving mechanical ventilation in the ICU4, with the intention of commencing intervention early, that is, within the first four days of mechanical ventilation18. However, this is conditional on the patients being physiologically and metabolically stable prior to the commencement of the intervention48. Clinical assessment, particularly neurological assessments of conscious state is required to determine whether to select a passive, active, or resisted mode of in-bed cycle ergometry. Modifications and troubleshooting may be required to optimize in-bed cycle ergometry and individualize therapy for patients in the ICU. The use of functional electrical stimulation can be incorporated for patients with severe weakness or those unable to actively participate in therapy49. However, electrical stimulation with in-bed cycle ergometry is beyond the scope of the current article.

Ingredient—In-bed cycle ergometer
The first essential ingredient for in-bed cycle ergometry is access to an in-bed cycle ergometer device (Table 2) and training in its use. An in-bed cycle ergometer is a specialized device to allow patients to perform passive, assisted, active, or resisted cycling exercise while remaining in bed. The main frame and base support the device securely over and beside the patient’s bed. Typically, these devices include mechanisms for adjustable height and width to accommodate different ICU bed types. The base features lockable casters or wheels for easy movement and positioning, whilst ensuring stability during ergometer use. The device may have additional straps to secure the frame to the bed.

The pedal mechanism supplies the cycling interface for the patient’s legs. The pedals often include straps to secure the feet with padded cushioning for comfort. The pedals are attached to crank arms, which are connected to a central axle, the motor, and resistance system. The resistance system can be adjusted to provide different levels of resistance for strengthening. The motor can move the pedals automatically to enable passive cycling if the patient is sedated and/or unable to voluntarily drive the pedals.

A computerized console, generally in tablet form, serves as the interface for clinicians to adjust settings and monitor performance. Typical features include speed control in revolutions per minute (RPM), and resistance control. Patient monitoring includes duration, distance, cadence, power output, and proportion of active versus passive input.

Positioning of the patient onto and off the cycle ergometer
Once the patient is identified, the ICU team is aware of the plan, and the equipment is available, clinicians set up the in-bed cycle ergometer at the bedside and adjust the height, width, and position to permit cycling motion and ensure patient comfort. The patient is in a semi-recumbent position, with the pelvis at the level of the anterior superior iliac spines (ASIS). The in-bed cycle ergometer is then positioned to align with the patient. The patient’s feet are positioned in the pedals to ensure that when the pedals are furthest from the pelvis, a small amount of knee flexion is maintained to avoid knee hyperextension or heel migration away from the pedals. Additionally, the pedals are positioned to avoid excessive hip flexion and external rotation when the pedals are closest to the pelvis. The in-bed cycle ergometer brakes and straps are fastened to maintain both the machine and patient throughout the intervention. Prior to starting the ergometer, clinicians confirm positioning by moving the ergometer through a full cycle.

Active monitoring of the patient for safety events and intervention if needed
Continuous reassessment and evaluation are warranted to monitor patients' response to the intervention including vital signs, fatigue, discomfort, or pain amongst others. Criteria for commencing in-bed cycle ergometry are provided in Table 1, with criteria for ceasing therapy listed in Table 2. These criteria are adapted from protocols of contemporary clinical trials of in-bed cycle ergometry and with consensus from the authors form the basis for monitoring therapy throughout50,51,52.

Safety responses
Immediately cease activity if stopping criteria are met. Remove the patient’s feet from the pedals. Reassess vital signs immediately. Notify the ICU team if instability persists.

Opportunities to practice
As patients progress from non-volitional (passive) to volitional (active-assisted or active) in-bed cycle ergometry, they require opportunities to practice to develop the skills to use the in-bed cycle ergometer for the activities planned by the therapist.

Instructions, feedback, knowledge of results, and motivation ingredients
As with any other therapy, providing verbal encouragement and feedback is important for optimal participation. The patient is provided with positive reinforcement regarding the benefits of participation in therapy throughout.

Increasing resistance duration of session
Once a patient has sufficient leg muscle strength to move the pedals without motor support and is consistently participating in the session, the clinician challenges the patient by adding resistance from the bike or extending the session time. If patients can complete in-bed cycle ergometry with resistance independently, they are considered for higher-level functional activity beyond in-bed cycle ergometry alone.

Whilst mobilization and in-bed cycle ergometry are relatively safe interventions, with an adverse event rate of 3%53 and 1%15, respectively, no serious adverse events have been reported with in-bed cycle ergometry, although mobilization is more common15. Importantly, in-bed cycle ergometry can be provided for patients who are unable to actively participate in mobilization (e.g., sedated patients) or those who are unable to tolerate a postural challenge to their haemodynamics, which are common issues present in the ICU.

Critical steps in implementation
Successful implementation of in-bed cycle ergometry in the ICU relies on several key considerations. Careful patient selection is essential to ensure safety and maximize benefit, with factors such as level of consciousness, haemodynamic stability, and the absence of contraindications guiding suitability19. Continuous patient monitoring and regular assessment are crucial for clinicians to tailor exercise intensity, detect any adverse responses, and adjust treatment according to the patient’s condition. Further, carefully maintained equipment and adequate staffing are vital to facilitate safe and effective delivery of the intervention, ideally requiring trained physiotherapists familiar with in-bed cycle ergometry protocols, infection control procedures, and equipment setup. Rehabilitation in the ICU is often challenging to deliver with adequate fidelity54. In-bed cycle ergometry has advantages in this regard, as frequency and duration are easily recorded, intensity and resistance may be controlled, and patient participation can be captured. Overall, this improves the reproducibility of the intervention and makes progression easier to adjust, modify, and control.

Common troubleshooting issues
Agitation, which may interfere with participation, should be carefully managed through calm reassurance, appropriate timing of sessions, or collaboration with the multidisciplinary team to adjust sedation or analgesia as required. Additionally, variations in body habitus may require adjustments in patient positioning or equipment setup to ensure safety and comfort throughout the intervention, or may contraindicate the use of in-bed cycle ergometry due to breaches in safe working loads of the devices.

Limitations
Despite the promise of in-bed cycle ergometry, limitations do exist. One key challenge is determining the appropriate exercise dose for patients mechanically ventilated in critical illness. Clinical trials to date have prescribed doses of interventions ranging from 20 min18 through to 60 min of activity48. Applying exercise prescription principles in critically ill patients is complex, and delivering higher doses or durations of activity may be limited by patient fatigue, medical instability, or clinician time constraints. Indeed, higher target doses of mobilization therapy have been difficult to achieve55, with low levels of physical activity recorded even in patients known to be participating in rehabilitation in the ICU43. In-bed cycle ergometry may provide a better opportunity to deliver a higher duration (dose) of physical activity than mobilization alone. The selection and timing of outcome assessment remain uncertain. Clinical trials have generally timed outcome assessment appropriately close to the cessation of the intervention, typically around ICU discharge18. The evolution of core outcome sets for rehabilitation trials in the ICU aims to address this heterogeneity to improve the ability to compare outcomes across trials56.

Comparisons with alternative rehabilitation strategies
Applying the RTSS to in-bed cycle ergometry, a specific mode of ICU rehabilitation, provides a structured framework for describing and analysing this complex intervention in the ICU environment. Whilst in-bed cycle ergometry has the highest fidelity of reporting (85% using CERT) compared with other modes of physical rehabilitation, physical rehabilitation requires improvement in the reporting of interventions in both intervention and comparator groups in clinical trials9. The RTSS requires clear designations of the clinician ingredients, mechanisms, and intended targets, which may facilitate improvements in consistency in the design of intervention delivery and reporting. Specifically, using the RTSS may help to distinguish between interventions that address muscle strength and endurance (body functions) and those that address physical function, with a description of the linking mechanism. By explicitly requiring the definition of these components, the use of the RTSS may strengthen the design of future clinical trials in physical rehabilitation.

Potential applications and future directions
Future directions for in-bed cycle ergometry in the ICU should focus on refining its application and expanding its potential beyond the lower limbs. Upper limb (arm) ergometry offers an opportunity to engage other muscle groups that may also contribute to physical function and improve cardiovascular fitness16. Determining the optimal timing of commencement remains an important topic of investigation. Advances in automated and artificial intelligence (AI)-driven patient monitoring may facilitate enhanced individualization of treatment by continuously tracking patient response and adjusting workload in real time. Continued innovation in the technology and application of these devices through research will improve the potential of exercise-based rehabilitation in the ICU. For example, virtual reality (VR) may be combined with in-bed cycle ergometry as an adjunct to improve cognitive stimulation and reduce the incidence of delirium57. These approaches are safe, feasible, and may improve the patient experience within the ICU58,59.

Conclusions
In-bed cycle ergometry is a safe, feasible, reproducible, and acceptable intervention in the ICU when delivered according to this standardized protocol and with appropriate patient selection and monitoring19. Evidence to date suggests that it improves physical function and contributes to reduced length of stay in the ICU and hospital15. As part of a structured rehabilitation program that includes early mobilization, in-bed cycle ergometry offers a practical alternative to increase physical activity, deliver a higher dose of exercise therapy, and counter the negative effects of prolonged bed rest. Ultimately, it may support physical recovery following critical illness and reduce the burden of physical disability for the increasing number of survivors of critical illness.

Disclosures

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Michelle Kho received the loan of 4-four RT300 supine cycle ergometers from Restorative Therapies (Baltimore, MD) for the CYCLE RCT. Restorative Therapies had no input in the content of this article or the decision to submit for publication.

Acknowledgements

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The authors would like to acknowledge the support of the Physiotherapy and Intensive Care Department at the Austin Hospital and St. Joseph’s Healthcare Hamilton.

Materials

List of materials used in this article
NameCompanyCatalog NumberComments
MOTOMed Letto2RECK-Technik GmbH & Co. KGinfo@motomed.com
RT300 SupineRestorative Therapies, Baltimore, MD https://restorative-therapies.com

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