Effect of foam roller application prior to proprioceptive neuromuscular facilitation stretching on hamstring flexibility and thigh skin temperature in healthy subjects

The aim of study was to examine the acute effect of foam roller (FR) application prior to proprioceptive neuromuscular facilitation (PNF) stretching on hamstring flexibility and thigh skin temperature in healthy subjects. Participants (n=60) were randomly allocated to PNF, PNF and foam roller (PNF+FR), PNF and vibrating foam roller (PNF+VFR), and control groups. PNF stretching was performed using contract-relax technique. Hamstring flexibility was assessed with Active Knee Extension (AKE) test and sit-reach test, and thigh skin temperature was assessed with thermal imaging at baseline, immediately after the application and after 30 minutes. AKE test results showed a higher increase in the PNF+VFR and PNF+FR groups compared to the PNF group immediately after application (p<0.05). They showed increase in the PNF, PNF+FR and PNF+VFR groups compared to the control group (p<0.001). For the sit and reach test, the increase was observed in all three interventions groups compared to the control group (p<0.001). While thigh skin temperature of the dominant extremity was showed increase in the PNF+FR and PNF+VFR groups 30 minutes after the application compared to the baseline (p<0.05), it was showed increase in the PNF+VFR group compared to the PNF group immediately after the application (p<0.05). A higher increase in skin temperature was observed in the PNF+VFR group compared to the PNF and control groups 30 minutes after the application (p<0.05). Combined warm-up (FR + PNF stretching) prior to activity seem to be beneficial compared to only stretching immediately after the application, but if a long-term effect such as 30 minutes is aimed, both warm-ups may be used. Combined applications are beneficial for warming up, as they cause a significant increase in skin temperature. One of the vibrating and traditional FR may be applied according to need. Key Words: Stretching, flexibility, thermal imaging, proprioceptive neuromuscular facilitation, foam roller.