Position-specific characteristics of forearm skeletal muscle microvascular function among college baseball players

Exercise training induces structural and functional arterial adaptations, often referred to as athlete's arteries, that optimize blood flow to active muscles.While previous studies have demonstrated position-specific differences in the brachial artery of baseball players, little is known about positionrelated differences at the microvascular level.This study examined positional differences in forearm skeletal muscle microvascular function among 90 male collegiate baseball players (23 pitchers and 67 fielders).Microvascular function was assessed using near-infrared spectroscopy during a vascular occlusion test (VOT).Tissue oxygen saturation (StO₂) was continuously monitored at depths of approximately 15 mm and 30 mm.Derived indices included StO₂ downslope, minimum StO₂, StO₂ upslope, peak StO₂, and the area under the curve (AUC).At a 15 mm depth, pitchers tended to exhibit a lower StO₂ downslope than fielders (P = 0.103), although no significant differences were observed for other indices.At a 30 mm depth, pitchers showed a significantly lower StO₂ downslope compared with fielders (P = 0.018), and this difference remained significant after adjustment for confounding variables (P = 0.029).No positional differences were observed for minimum StO₂, StO₂ upslope (reoxygenation rate), peak StO₂, or AUC at either depth.These findings provide limited, depth-specific evidence of a positional difference in forearm muscle oxygenation dynamics at rest.Because this study was an exploratory cross-sectional investigation and no formal correction for multiple comparisons was applied, the results should be interpreted cautiously.