Intradialytic Cycling Does Not Significantly Reduce Myocardial Stunning in Hemodialysis Patients

A multisite randomized trial found intradialytic exercise led to a modest, nonsignificant reduction in myocardial stunning among patients receiving hemodialysis, highlighting both the promise and limitations of exercise as a cardiovascular intervention in this population.

Clara Bohm, MD, a nephrologist and associate professor in the Department of Internal Medicine at the University of Manitoba, presented results from a multicenter, randomized 12-week trial of intradialytic cycling targeting hemodialysis-induced myocardial stunning at the World Congress of Nephrology (WCN).

Myocardial stunning is defined by transient, repeated episodes of ischemia-induced left ventricular dysfunction and is common during hemodialysis. It has been associated with increased cardiovascular morbidity and mortality. Given the substantial symptom burden and elevated cardiovascular risk faced by patients on dialysis, investigators have increasingly explored exercise as a potential therapeutic strategy.

Intradialytic exercise refers to physical activity performed during hemodialysis sessions, typically involving low- to moderate-intensity movements such as stationary cycling or resistance training, designed to improve physical function and potentially mitigate treatment-related complications.

The rationale for targeting myocardial stunning with exercise is grounded in both clinical need and biological plausibility. Exercise may address several contributing mechanisms, including underlying cardiac disease and vascular dysfunction. Additionally, aerobic exercise has been shown in the general population to induce ischemic preconditioning, in which repeated, low-level cardiac stress improves resilience to more severe ischemic events.

Despite this rationale, prior research has been limited. Many studies have been small, observational, and conducted in highly selected populations, raising concerns about generalizability. These studies have also often been cross-sectional or nonrandomized, introducing potential bias and limiting insight into long-term effects.

To address these limitations, investigators designed a multicenter randomized trial with minimal exclusion criteria to better reflect real-world patients receiving hemodialysis. Participants in the intervention arm completed 60 minutes of intradialytic exercise three times per week over a 12-week period.

At study completion, the control group demonstrated no change in the number of stunned myocardial segments from baseline. In the exercise group, investigators observed a reduction of approximately 1.3 stunned segments after 12 weeks; however, the difference did not reach statistical significance.

“We did not detect a significant effect of exercise on myocardial stunning,” Bohm said. “It’s possible the effect is still there, but smaller than what’s been seen in more selective populations.”

Importantly, the study cohort differed meaningfully from those in prior trials. The population included a higher proportion of women, approximately 20% Indigenous participants in the US, and about 35% of patients in each arm with significant heart failure—groups often underrepresented in earlier studies.

Adherence to the exercise intervention was consistent with other behavioral trials, with participants completing approximately 65% of prescribed sessions and achieving target intensity overall. However, subgroup analysis suggested disparities in engagement, particularly among women, who participated in fewer sessions, exercised for shorter durations, and at lower intensity.

“There’s a lot of enthusiasm around exercise as a therapy,” Bohm said. “But it’s critical that we test these interventions in larger, representative populations so we know what truly works.”

The study was conducted through a collaborative network of researchers focused on advancing exercise science in kidney disease, including the Global Renal Exercise Network.

References

1. Bennett PN, Penny JD, McIntyre CW, et al. Randomized Controlled Trial of Intradialytic Cycling as Kidney Exercise Rehabilitation for Cardiac Stunning in Hemodialysis (TICKERS_HD): A Clinical Research Protocol. Canadian journal of kidney health and disease. 2026;13:20543581251391112. doi:https://doi.org/10.1177/20543581251391112

2. Safoora Shahzeidi, Firouzeh Moeinzadeh, Shahidi S. Evaluating the effect of intradialytic cycling exercise on quality of life and recovery time in hemodialysis patients: A randomized clinical trial. 2022;27(1):84-84. doi:

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