Impact of Graded Passive Cycling on Hemodynamics, Brain, and Heart Perfusion in Healthy Adults

Cerebral blood flow and immediate and sustained executive function benefits following single bouts of passive and active exercise

Passive exercise occurs when an individual's limbs are moved via an external force and is a modality that increases cerebral blood flow (CBF) and provides an immediate postexercise executive function (EF) benefit. To our knowledge, no work has examined for how long passive exercise benefits EF. Here, healthy young adults (N = 22; 7 female) used a cycle ergometer to complete three 20-min conditions: passive exercise (via mechanically driven flywheel), a traditional light intensity (37 W) "active" exercise condition (i.e., via volitional pedalling) and a non-exercise control condition. An estimate of CBF was obtained via transcranial Doppler ultrasound measurement of middle cerebral artery blood velocity (MCAv) and antisaccades (i.e., saccade mirror-symmetrical to a target) were completed prior to and immediately, 30- and 60-min following each condition to assess EF. Passive and active exercise increased MCAv; however, the increase was larger in the latter condition. In terms of antisaccades, passive and active exercise provided an immediate postexercise reaction time benefit. At the 30-min assessment, the benefit was observed for active but not passive exercise and neither produced a benefit at the 60-min assessment. Thus, passive exercise provided an evanescent EF "boost" and is a finding that may reflect a smaller cortical hemodynamic response.

Impact of Graded Passive Cycling on Hemodynamics, Cerebral Blood Flow, and Cardiac Function in Septic ICU Patients

Background: In-bed passive cycling is considered a safe and feasible early mobilization technique in intensive care unit (ICU) patients who are unable to exercise actively. However, the impact of varying intensity of passive cycling on perfusion and function of ischemia-prone organs is unknown. In this study, we assessed the impact of a graded passive cycling protocol on hemodynamics, cerebral blood flow, and cardiac function in a cohort of septic ICU patients. Methods: In consecutive patients presenting with sepsis, we measured global hemodynamic indices, middle cerebral artery velocity (MCAv), and cardiac function in response to a graded increase in passive cycling cadence. Using 5-min stages, we increased cadence from 5 to 55 RPM in increments of 10 RPM, preceded and followed by 5 min baseline and recovery periods at 0 RPM. The mean values obtained during the last 2 min of each stage were compared within and between subjects for all metrics using repeated-measures ANOVA. Results: Ten septic patients (six males) completed the protocol. Across patients, there was a 5.2% reduction in MCAv from baseline at cycling cadences of 25-45 RPM with a dose-dependent decrease of MCAv of > 10% in four of the 10 patients enrolled. There was a 16% increase in total peripheral resistance from baseline at peak cadence of 55 RPMs and no changes in any other measured hemodynamic parameters. Patient responses to passive cycling varied between patients in terms of magnitude, direction of change, and the cycling cadence at which these changes occurred. Conclusions: In septic patients, graded passive cycling is associated with dose-dependent decreases in cerebral blood flow, increases in total peripheral resistance, and either improvement or worsening of left ventricular function. The magnitude and cadence threshold of these responses vary between patients. Future studies should establish whether these changes are associated with clinical outcomes, including cognitive impairment, vasopressor use, and functional outcomes.

Effects of In-Bed Cycle Exercise in Patients With Acute Stroke: A Randomized Controlled Trial

Objective

To investigate the effects of in-bed cycle exercise in addition to usual care in patients with acute stroke, National Institutes of Health Stroke Scale (NIHSS) 7-42, regarding walking ability, functional outcomes, and inpatient care days.

Design

Randomized controlled trial.

Setting

Hospital care.

Participants

Patients (N=56) with stroke NIHSS 7-42 were recruited 24-48 hours after stroke onset from 2 stroke units in Sweden.

Interventions

Both groups received usual care. The intervention group also received 20 minutes bed cycling 5 days per week with a maximum of 15 sessions.

Main Outcome Measures

The primary outcome was median change in walking ability measured with the 6-minute walk test (6MWT). Secondary outcome measures included the median change in modified Rankin Scale (mRS), Barthel Index (BI) for activities of daily living, and inpatient care days. Measurements were performed at baseline, post intervention (3 weeks), and at 3-month follow-up.

Results

There was no significant difference in change of walking ability (6MWT) from baseline to follow-up between the intervention and control groups (median, 105m [interquartile range [IQR, 220m] vs 30m [IQR, 118m], respectively, P=.147, d=0.401). There were no significant differences between groups regarding mRS, BI, or inpatient care days. Patients with less serious stroke (NIHSS 7-12) seemed to benefit from the intervention.

Conclusion

Although this study may have been underpowered, patients with stroke NIHSS 7-42 did not benefit from in-bed cycle exercise in addition to usual care after acute stroke. A larger study is needed to confirm our results.