Effects of warm-up on muscle hemodynamics: a focus on muscle strength and exercise intensity in women.

In sports, warm-up is important to prevent injuries and improve performance. Previous studies have reported that warm-up increases blood flow in the conduit arteries of active limbs. However, its effects on downstream active muscles remain unclear, particularly in women. This study aimed to investigate the effect of warm-up on blood flow dynamics in active muscles of female participants using diffuse correlation spectroscopy, a noninvasive optical technique that measures blood flow velocity in peripheral tissues. Thirteen female participants performed two consecutive bouts of rhythmic handgrip exercises at 10, 30, and 50% of their maximum voluntary contraction strength. The increase in muscle blood flow that was observed during the second bout relative to the first was considered as an effect of warm-up. The results showed that warm-up significantly enhanced muscle blood flow during subsequent exercise. Subgroup analysis indicated that participants with higher grip strength may require more intense exercises to achieve the full benefits of a warm-up.Clinical Relevance- Diffuse correlation spectroscopy enables measurement of muscle blood flow, thereby revealing the optimum exercise intensity to achieve warm-up for different individuals. This can contribute to the development of individualized programs in sports and medical settings.