The association between cardiovascular health and flexibility appears, on the surface, unlikely. The mechanisms connecting them are not immediately obvious. Yet a series of studies published primarily in the American Journal of Physiology has established a consistent and statistically significant relationship between trunk flexibility, as measured by the sit-and-reach test, and arterial stiffness, as measured by pulse wave velocity. This relationship is independent of other cardiovascular risk factors and appears to be causal rather than purely correlational.
The Research Base
Yamamoto et al. at the University of Texas at Austin first documented the flexibility-arterial stiffness relationship in a 2009 study of middle-aged and older adults. Those with poor sit-and-reach performance had significantly higher arterial stiffness on pulse wave velocity measurement, and the relationship was stronger in adults over 40 than in younger adults, suggesting that the shared mechanism becomes more important with age. Subsequent studies by the same group demonstrated that a 12-week stretching programme improved arterial flexibility in adults with elevated arterial stiffness, providing evidence that the relationship is modifiable.
The Shared Mechanism
The proposed mechanism links musculotendinous flexibility and arterial flexibility through their shared dependence on connective tissue quality. Arteries, like tendons and muscle sheaths, contain collagen and elastin as primary structural components. The same ageing processes that produce collagen cross-linking and reduced extensibility in musculotendinous structures, elevated AGE formation, dehydration, and oxidative stress, produce parallel changes in arterial collagen. Arterial stiffness increases with age for the same biochemical reasons that flexibility decreases: the two are expressions of the same underlying tissue ageing process.
Stretching as a Cardiovascular Intervention
A clinical implication of the flexibility-arterial stiffness relationship is that stretching programmes may have indirect cardiovascular benefits through their effects on arterial compliance. Several small randomised trials have found that regular stretching programmes reduce resting blood pressure by 2 to 6mmHg, a clinically meaningful effect size. The mechanism is proposed to involve improvements in vascular endothelial function and arterial compliance from both the direct effects of stretching on arterial walls and the reduction in sympathetic nervous system tone associated with relaxation-based stretching practice.
- Perform regular whole-body stretching or yoga as part of a cardiovascular health strategy, not only as a flexibility intervention
- Reduce arterial AGE formation through diet: lower sugar, refined carbohydrate, and ultra-processed food intake
- Measure your resting blood pressure before and after an 8-week stretching programme: studies show reductions of 2 to 6mmHg
- Address the shared modifiable factors: blood sugar, hydration, antioxidant intake, and anti-inflammatory eating all support both arterial and connective tissue health
- Include the sit-and-reach as a simple annual health check alongside blood pressure and resting heart rate
Sources
- Yamamoto, K., et al. (2009). Poor trunk flexibility is associated with arterial stiffening. American Journal of Physiology: Heart and Circulatory Physiology, 297(4), H1314-H1318.
- Cortez-Cooper, M.Y., et al. (2008). The effects of resistance training on arterial stiffness in older adults. European Journal of Applied Physiology, 103(5), 531-537.