In more recent years, by means of HRV measurement techniques, the impact of OMT (osteopathic manipulative treatment) on cardiac sympathovagal balance has been assessed.
7-10 For example, a single cervical OMT protocol (upper cervical spine manipulation) was applied to healthy normotensive participants under resting conditions, and its effects were compared with sham therapy (placement of fingers with no pressure exerted).
9 The treatment resulted in an increase in the spectral power in the high-frequency (HF) band, indicative of parasympathetic modulation of heart rate (HR) and a decrease in the ratio of low-frequency (LF) to HF power (LF:HF), indicating sympathovagal balance, compared with the sham treatment.
9 In a study by Henley et al,
7 the immediate effects of OMT were explored not only at rest but also after a 50° head-up tilt challenge, a postural change that determines sympathetic excitation, concomitant vagal withdrawal, and a shift in sympathovagal balance toward sympathetic prevalence.
11 The cervical myofascial release technique dampened tilt-induced sympathetic prevalence significantly, as shown by a lower LF:HF ratio compared with that found after sham manipulation.
7 In a 2015 study, Ruffini et al
10 reported a significant increase in HF power as well as a reduction in LF:HF ratio in resting participants undergoing OMT, thus supporting the view that OMT influences autonomic neural modulation of HR by increasing parasympathetic activity and shifting sympathovagal balance toward vagal prevalence.
10 This experimental evidence suggests that OMT is a potentially powerful approach to enhance the parasympathetic input to the heart and hence prevent exaggerated stress-induced sympathetically driven cardiac activations. However, we are not aware of any study that has explored the protective potential of OMTh in challenging contexts involving mental stress, which has been reported to have large effects on cardiac autonomic modulation.
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