Central and peripheral responses to static and dynamic stretch of skeletal muscle: mechano- and metabo-reflex implications

Passive static stretching (SS), circulatory cuff occlusion (CCO), and the combination of both (SS+CCO) have been used to investigate the mechano- and metabo-reflex, respectively. However, the effects of dynamic stretching (DS) alone or in combination with CCO (DS+CCO) on the same reflexes have never been explored. The aim of the study was to compare central and peripheral hemodynamic responses to DS, SS, DS+CCO, and SS+CCO. In ten participants, femoral blood flow (FBF), heart rate (HR), cardiac output (CO), and mean arterial pressure (MAP) were assessed during DS and SS of the quadriceps muscle with and without CCO. Blood lactate concentration [La-] in the lower limb undergone CCO was also measured. FBF increased significantly in DS and SS by 365±98 and 377±102 ml/min, respectively. Compared to baseline, hyperemia was negligible during DS+CCO and SS+CCO (+11±98 and +5±87 ml/min, respectively). DS generated a significant, sustained increase in HR and CO (40s), while SS induced a blunted and delayed, cardioacceleration (20s). After CCO, [La-] in the lower limb increased by 135%. Changes in HR and CO during DS+CCO and SS+CCO were similar to DS and SS alone. MAP decreased significantly by 5% during DS and SS, didn't change in DS+CCO, and increased by 4% in SS+CCO. The present data indicate a reduced mechano-reflex response to SS compared to DS (i.e., different HR and CO changes). SS evoked a hyperemia similar to DS. The similar central hemodynamics recorded during stretching and [La-] accumulation suggest a marginal interaction between mechano- and metabo-reflex.