Patil, Pranoti R    Karad, INDIA.
Devi, Poovishnu T

Cureus [Cureus] 2026 Aug 29; Vol. 18 (8), pp. e115400. Date of Electronic Publication: 2026 Aug

Headings by Dr Older

Background Patients undergoing coronary artery bypass grafting (CABG) commonly experience reduced lower-limb strength, impaired balance, decreased functional mobility, and autonomic dysfunction during the postoperative period. These impairments may increase fall risk and limit daily activities. The Otago Exercise Program (OEP) is an evidence-based exercise intervention designed to improve lower-limb strength, balance, and functional performance, while resonance frequency breathing (RFB) has been shown to enhance cardiac autonomic regulation and heart rate variability (HRV). Although both interventions have demonstrated individual benefits, evidence regarding their combined application in phase II cardiac rehabilitation following CABG remains limited. Therefore, this study aimed to evaluate the effects of a combined OEP and RFB intervention on balance, lower-limb strength, functional mobility, and cardiac autonomic function in post-CABG patients.
Objective To evaluate the effects of a combined OEP and RFB intervention on balance, lower-limb strength, functional mobility, and cardiac autonomic regulation as evaluated via HRV in patients undergoing phase II cardiac rehabilitation following CABG.
Materials and methods A single-group pre-test and post-test experimental study was conducted among 40 post-CABG patients aged 40 to 60 years. The eight-week intervention combined supervised OEP multi-component exercises three times per week with daily home-based RFB paced precisely at six breaths per minute for 15 to 20 minutes. Lower extremity functional strength was evaluated by the 30-Second Chair Stand Test, and dynamic mobility was monitored with the Timed Up and Go (TUG) test. Static postural stability was evaluated using the Four-Stage Balance Test. Cardiac autonomic regulation was evaluated using short-term five-minute electrocardiographic (ECG) time-domain metrics, specifically tracked through the mean R-R interval and the root mean square of successive differences (RMSSD).
Results Improvements were observed following the intervention. The TUG test results improved from 17.95 ± 2.86 seconds to 14.68 ± 2.93 seconds (p < 0.001), indicating improvement in functional mobility. The lower limb strength also improved. The 30-Second Chair Stand Test scores went up from 13.03 ± 1.83 to 15.78 ± 2.03 repetitions (p < 0.001). We also saw improvements in balance, tandem stance, and single-leg stance (p < 0.0001). Autonomic function also improved, with an increase in RMSSD from 18.03 ± 2.59 ms to 21.96 ± 2.59 ms (p < 0.001); these findings suggest improved parasympathetic activity.
Conclusions The combined OEP and RFB intervention may support physical function, balance, functional mobility, and autonomic regulation in patients undergoing phase II cardiac rehabilitation after CABG surgery. The intervention appeared to be safe and useful in a home-based rehabilitation setting and may be a helpful approach in cardiac rehabilitation. However, the absence of a control group and separate OEP and RFB groups limits the ability to determine their individual or combined effects. Future studies with appropriate control and separate intervention groups are needed to confirm these findings.