Background: Breathing retraining and manual therapy (MT), delivered independently or together, influence autonomic activity, and improve symptoms in patients with chronic conditions. This study evaluated the effects of breathing retraining and osteopathic MT on cardiac autonomic measures and breathing symptoms during spontaneous breathing in healthy active adults.

Methods: Participants (n = 18) received breathing retraining and four, weekly manual therapy sessions, randomised to start immediately, or after 6-week delay. Heart-rate (HR) variability was assessed as a 7-day average of waking 6-min electrocardiograms, using time (logarithm of root-mean-square of successive differences; LnRMSSD) and frequency domain (logarithm of high-frequency; LnHF) measures. Recordings were taken before, one week following intervention or delay, and then following the later intervention for those with delayed starts. Changes were compared between those who received and had yet to receive the intervention, and before and after treatment for the whole cohort.

Results: Following the intervention, HR-variability measures increased 4% overall (Effect Sizes: 1.0-1.1) for the whole cohort. Between-group analyses showed that the immediate-start group increased more than the delayed start group: LnRMSSD 0.27 (0.02-0.52; 95%CI) ln.ms, and LnHF 0.41 (-0.01-0.84) ln.ms2 for immediate start; compared with LnRMSSD -0.09 (-0.29-0.11) ln.ms, and LnHF -0.19 (-0.59-0.22) ln.ms2 (P = 0.02-0.03 for interaction) for delayed start. Resting HR decreased following intervention in the whole cohort (Effect Size -0.8; P = 0.02).

Conclusion: A 6-week osteopathic treatment consisting of breathing retraining and MT is beneficial in raising HR-variability compared to no treatment, and may induce favourable (parasympathetic over sympathetic) autonomic modulation.