Abstract
Frailty represents diminished reserve across multiple physiologic systems, accompanied by increased vulnerability to stressors and increased morbidity and mortality. With population aging, strategies to prevent and manage frailty are priorities in clinical medicine and public health. Current evidence-based approaches to frailty management are multimodal in nature. Yoga, an increasingly popular and highly adaptable mind-body practice, is multi-component, incorporating physical postures, breathing practices, meditation, and other elements, and may be a strategy for frailty management. Here, we summarize the evidence linking yoga practice to mitigation of age-related degradation across multiple physiologic systems, including cardiovascular, pulmonary, musculoskeletal, and nervous systems. We discuss putative mechanisms of action including modulation of the hypothalamic–pituitary–adrenal axis. Finally, we consider implications for clinical practice and future research.
Introduction
Frailty is characterized by increased vulnerability to stressors mediated by age-related decline in physiologic functioning across multiorgan systems, increasing risk for mortality and adverse outcomes [, , , ]. Approximately 11% of community-dwelling older adults are frail, with rates approaching 50% over age 85 [,]. There is urgent need for interventions to prevent and manage frailty.
Currently, evidence-based interventions include multicomponent physical activity programs, nutrition supplementation, health behavior education, and home environment modification [, , , , , , ]. Yoga is a multicomponent mind-body practice that includes physical poses, breathing exercises, meditation, and other elements. In a systematic review of 33 studies of yoga-based interventions in older adults, yoga positively impacted frailty markers []. Additionally, yoga likely positively impacts cellular and molecular hallmarks of aging []. In this review, we summarize evidence for yoga on clinically apparent, age-related physiologic decline across the cardiovascular, pulmonary, nervous, and musculoskeletal systems.
Cardiovascular system
Age-related changes in cardiovascular function are characterized by arterial stiffness, impaired myocardial relaxation, reduced beta-adrenergic response, and reduced endothelium-dependent vasodilation []. Functionally, these changes impair response to increased demand or stressors, leading to reduced maximal oxygen capacity, peak cardiac output, heart rate (HR), and ejection fraction. Both incidence and prevalence of pathologic cardiovascular disease increase with aging, and especially frailty [, , , ]. Frail older adults exhibit glucose intolerance and insulin resistance, even in the absence of diabetes, increasing cardiovascular risk [].
Yoga is effective for lowering blood pressure (BP) in middle-aged and older adults, with and without hypertension [, , , ]. In a review of 49 randomized controlled trials (RCTs) with 3517 participants (mean age 49.2 ± 19.4 years), yoga >3 sessions per week elicited mean systolic BP (SBP) reduction of 11 mmHg and diastolic BP (DBP) reduction of 6 mmHg []. In another review of 13 RCTs in elevated BP (753 participants), yoga and meditation were effective for BP reduction in >60 years (yoga: SBP −11.40 mmHg [95% CI: −14.57, −8.22], p < 0.001; DBP −2.37 mmHg [−4.35, −0.38], p = 0.02 vs. meditation: SBP −8.89 mmHg [−9.88, −7.89], p < 0.001; DBP −6.25 mmHg [−6.85, −5.66], p < 0.001) [].
Heart rate variability (HRV), reflecting autonomic beat to beat HR control, is reduced in frail older adults []. A systematic review (14 RCTs, 821 participants; mean age 37.3 [11.5–68.5]) found no difference in HRV after yoga vs. usual care (expiratory to inspiratory ratio, standardized mean difference [SMD] 0.63 [−0.72, 1.99], p = 0.36; 30:15 ratio SMD 0.20 [−0.43, 0.84], p = 0.53) []. Recent RCTs demonstrate mixed evidence [, , ]; conclusions may be limited by methodological issues in HRV measurement [].
Yoga also enhances metabolic profiles, with estimated mean hemoglobin A1c reduction of 0.5%, and improvements in lipids and body composition [, , ].
Pulmonary system
Lung elasticity decreases with aging, leading to reduced total alveolar surface area. Additionally, chest wall compliance is reduced due to decreased respiratory muscle mass, rib cage stiffening, and kyphosis. Clinically important changes in spirometry develop: (1) airflow limitation (reduced FEV1/FVC [forced expiratory volume in 1 s to forced vital capacity]), (2) air trapping (increased residual volume), and (3) reduced diffusion capacity for carbon monoxide. Functionally, older adults experience expiratory flow limitation, higher respiratory rate, and reduced exercise capacity []. In chronic obstructive pulmonary disease (COPD), these changes contribute to decreased physical activity and socialization [].
A review (16 studies, 1233 participants, mean FEV1 30%–51% predicted) evaluated yogic breathing in COPD, identifying 4–15 weeks of practice improves exercise capacity vs. no intervention (six-min walk test [6MWT] mean difference 45 m [,]); without consistent effect on dyspnea or quality of life (QOL) []. Other systematic reviews in COPD reported consistent improvements in 6MWT and FEV1, with mixed evidence for dyspnea, QOL, and FVC [, , , ].
Breathing techniques are performed while practicing poses and/or during standalone sessions. General physical conditioning from poses may strengthen respiratory muscles and improve thorax alignment, promoting optimal breathing mechanics []. Yogic breathing strengthens respiratory muscles and promotes efficient diaphragm use [,]. Direct stimulation of vagal afferents in the lungs reduces sympathetic and enhances parasympathetic tone [,]. Finally, chemoreflex sensitivity is reduced, enhancing gas exchange and improving exercise performance [].
Nervous system
Brain aging is characterized by gray matter atrophy, age-related athero- and arteriosclerosis, and other cellular and structural changes []. Cognitive aging includes reduced processing speed, working memory, and memory retrieval with improved wisdom and positive thinking []. Cognitive and motor control are interconnected, leading to increased dual-tasking cost (walking imbalance during an unrelated cognitive task) [].
A meta-analysis (15 RCTs, all ages) described moderate effect of yoga for global cognition (Hedge’s g = 0.33), attention and processing speed (g = 0.29), executive function (g = 0.27), and memory (g = 0.18) []. In older populations (12 studies, 912 participants, mean age 60–75), yoga had moderate effect on memory (Cohen’s d = 0.38), executive function (d = 0.40), and attention and processing speed (d = 0.33) []. Others have described similar improvements in cognition, stress, mood, and sleep [, , , ].
Experienced yoga practitioners exhibit structural brain changes, with increased insular cortex gray matter density (interoceptive awareness and empathy) [] and hippocampal gray matter volume, compared to matched controls [, , , ]. Functional neuroimaging demonstrates increased frontal executive and attentional network connectivity [].
Prolonged stress, leading to chronically elevated cortisol levels, promotes hippocampal atrophy, accelerating cognitive decline []. Yoga may mitigate cognitive changes by enhancing stress regulation and neurocognitive resource efficiency []. Mindful yoga movements and/or meditation may explain benefits for cognitive health compared to traditional physical exercise.
Musculoskeletal system
Skeletal aging is characterized by reduced bone mass and morphological changes in bone matrix microarchitecture, resulting in kyphosis, osteopenia, osteoporosis, and osteoarthritis [,]. Loss of muscle mass begins in the third decade; by age 70, 24% of muscle mass and 40% of motor neuron units are lost, leading to loss of muscle speed and power, further accelerated in frailty [].
One meta-analysis (39 RCTs, 2325 participants, mean age 51.4–72.5) assessed effects of mind-body exercise on bone mineral density (BMD), with yoga leading to significant improvements (mean difference = 0.11 [0.4, 0.18], p = 0.004) []. In another meta-analysis (11 studies, 591 participants, ages 45–78), yoga did not impact BMD (pooled effect size [ES] 0.07 [−0.05 to 0.19]) []. Yoga may maintain BMD through physical poses offering body weight resistance and balance training, but additional benefit is likely found with increased weight-bearing exercise []. Spinal flexion, emphasized in some yoga postures, has been associated with greater risk of vertebral fractures, though events are rare [].
Yoga may prevent age-related muscle loss and sarcopenia. In a meta-analysis (22 RCTs, 967 participants, mean age 61.0–83.8), yoga vs. inactive control had medium effect on balance (ES 0.7) and small effect on lower limb strength (ES 0.45); yoga vs. active control showed no effect on balance and small effect on lower limb strength (ES 0.48) []. Yoga postures focus on functional movement and upper extremity strength, but again may not be as beneficial as resistance training.
Discussion
Yoga is a promising approach for frailty prevention and management. Core systems responsible for maintaining homeostasis (stress-response, metabolic, musculoskeletal) are perturbed in frailty []. Emerging evidence suggests yoga positively impacts these domains, likely conferring resilience by modulating the stress-response. Bottom-up stimuli (poses, breathing) increase afferent parasympathetic signals while top-down cognitive control (meditation) modulates brainstem sympathetic efferents and inflammation through the hypothalamic–pituitary–adrenal axis () [,].
Yoga is an attractive non-pharmacologic intervention for frailty given its multimodal nature and evidence it targets multiple geriatric syndromes simultaneously. It is popular, feasible, acceptable, adaptable, and safe [, , ]. Work is needed to understand efficacy and safety at different stages of frailty. Finally, frailty and dynamic measures of resilience should be considered as outcomes for future studies [].
Funding
Primary funding source: none. J.L. is supported by 10.13039/100000102HRSA GACA K01HP49053‐01‐01 and Harvard Medical School Osher Center for Integrative Medicine Pilot Research Grant. A.R.O. is supported by VA CSR&D CDA-2 award IK2-CX001800. P.M.W. is supported by NIH K24 AT009282.
Disclosures
P.M.W. is the founder and sole owner of the Tree of Life Tai Chi Center. Peter Wayne’s interests were reviewed and managed by the Brigham and Women’s Hospital and Partner’s HealthCare in accordance with their conflict of interest policies. The authors have no other conflicts of interest to declare.
Author contributions
J.L. and A.R.O. were responsible for design. J.L., E.J.F., K.M., and B.T. were responsible for writing. J.L., P.M.W., and A.R.O. were responsible for editing. J.L. generated figures.