Effects of foam rolling on vastus intermedius and lateralis microvascular blood flow

Introduction: Foam Rolling (FR) as a technique of self-massage has become a widely used intervention in clinical and sports practice. It is assumed that FR leads to an increased intramuscular microvascular blood flow (MBF), and therefore is commonly recommended as a warm-up or regeneration method. However, no data validate the effects of FR on MBF. This study aimed to assess whether FR increases intramuscular MBF using contrast-enhanced ultrasound (CEUS). Methods: Ten healthy athletes performed a standardized FR intervention applied to the lateral thigh (3 sets: 45 s FR, 20 s rest). Intramuscular perfusion was determined by CEUS under resting conditions (t0), immediately (t1), and 30 min (t2) after the intervention. Peak enhancement (PE), wash-in rate (WiR), and wash-in perfusion index (WiPI) were evaluated as quantitative perfusion parameters in vastus lateralis (VL) and intermedius (VI) muscle separately via regions of interest mapping. Results: Immediately after the intervention (t1), perfusion parameters showed a non-significant decrease in VL (p = 0.3; PE:-32.1%, WiPI:-29.6%, WiR:-50.4%) and VI (p = 0.4; PE:-10.3%, WiPI:-6.4%, WiR:-35.6%). A non-significant decrease was found at t2 in VL (p = 0.2; PE:-34%, WiPI-33.9%, WiR-61.2%) and VI (p = 0.2; PE-17.6%, WiPI-13.8%, WiR-43.2%). Conclusions: The common assumption of intramuscular MBF improvement due to FR could not be confirmed for up to 30 min after the intervention. If an increase in intramuscular metabolism or MBF is intended, we recommend that alternative methods (i.e., traditional warm-up) should be preferred.