New Health Benefits Cited with Good Trunk Flexibility

Modified Sit and Reach Test: Perform sitting on floor or in chair to reduce back strain.

Written by
Gina Cortese-Shipley, MS

Have you ever taken the “Sit and Reach” test? It is a basic physical fitness test given to participants of all ages to determine trunk flexibility? A good score on this test generally indicates good overall flexibility. Good flexibility in turn is associated with improved range of motion in movement, and thought to reduce the risk of exercise related injury. But there is new evidence that being flexible has a strong health related benefit of reducing arterial stiffness. Arterial stiffness in turn is associated with increases in blood pressure which is an increased risk for coronary (heart) artery disease and kidney failure.

To test the theory that poor trunk flexibility is associated with arterial stiffening, lead researcher, Kenta Yamamoto, with the University of North Texas Health Science Center in Ft. Worth, tested 526 adults and grouped them by age: 20-39 young; 40-59 middle age; 60-83 older.¹ Arterial stiffness was assessed by the brachial-ankle pulse wave velocity. Subjects were classified as either “poor flexibility” or “high flexibility” after the sit and reach test.

Researchers tested for all three components of fitness: cardiovascular, muscular strength, and flexibility. The findings demonstrated that flexibility was an independent factor in determining risk for arterial stiffening. Also, the results showed that age related arterial stiffness was greater in the poor flexibility subjects than the high flexibility subjects of middle age and older age. In the young age groups there was no observed relationship of flexibility and arterial stiffness.

Further findings from this study showed a positive relationship between cardiovascular fitness and flexibility. In general because exercise includes flexibility exercise as seen in stretching for warm up and cool down, active adults are most likely to demonstrate good flexibility than inactive adults.

Since trunk flexibility can be easily assessed on adults of all ages in practical field setting, this measurement may become a “preventive medicine score” for the prevention of arterial stiffening due to aging. Furthermore, consideration should also be given to the promotion of regular stretching, yoga, and pilates because of their contribution to increased flexibility.

¹Yamamoto, K., Kawano, H., Gando, Y., Iemitsu, M., et al. Poor Trunk Flexibility is associated with arterial stiffening. Am J Physiol Heart Cir Physiol. 297, H1314-H 1318, 2009.