ABSTRACT 

Background:

Stress places a metabolic burden on homeostasis and is linked to heightened sympathetic activity,
increased energy expenditure and pathology. The yogic state is a hypometabolic state that corresponds with
mind-body coherence and reduced stress. This study aimed to investigate metabolic responses to stress and different
yoga practices in regular yoga practitioners (YP), non-yoga practitioners (NY) and metabolic syndrome patients (MS).

Methods:

YP (n = 16), NY (n = 15) and MS (n = 15) subjects underwent an experimental protocol that comprised of
different 5-minute interventions including mental arithmetic stress test (MAST), alternate nostril breathing (ANB),
Kapabhati breathing (KB) and meditation (Med) interspersed with 5 minutes of quiet resting (neutral condition (NC)).
During the intervention periods continuous body weight adjusted oxygen consumption (VO2ml/min/kg) was measured
using open circuit indirect calorimetry with a canopy hood.

Results:

This is the first study to report oxygen consumption (OC) in yoga practitioners during and after MAST and the
first to report both within and between different populations. The results were analysed with SPSS 16 using 3X9
mixed factorial ANOVAs. The single between-subject factor was group (YP, NY and MS), the single within-subject factor
was made up of the nine intervention phases (NC1, MAST, NC2, ANB, NC3, KB, NC4, Med, NC5). The results demonstrated
that the regular YP group had significantly less OC and greater variability in their OC across all phases compared to the
MS group (p = .003) and NY group (p = .01). All groups significantly raised their OC during the mental arithmetic stress,
however the MS group had a significantly blunted post-stress recovery whereas the YP group rapidly recovered back to
baseline levels with post stress recovery being greater than either the NY group or MS group.

Conclusions:

Yoga practitioners have greater metabolic variability compared to non-yoga practitioners and metabolic
syndrome patients with reduced oxygen requirements during resting conditions and more rapid post-stress recovery.
OC in metabolic syndrome patients displays significantly blunted post-stress recovery demonstrating reduced metabolic
resilience. Our results support the findings of previous randomised trials that suggest regular yoga practice may mitigate
against the effects of metabolic syndrome.

Clinical trial number: ACTRN12614001075673; Date of Registration: 07/10/2014.