Acute effects of low-intensity resistance combined with blood flow restriction and high-intensity resistance exercise on lower extremity explosive strength, pennation angle and muscle-tendon stiffness in male sprinters
Authors: Zhang Junjie , Ye Jun , Liu Haiyuan 
Published: February 2024

The purpose of this study was to investigate the ecute effect of combining low-intensity resistance exercises with a blood flow restriction intervention and high-intensity resistance exercises on sprint ability, vertical jump performance, rectus femoris pennation angle, and lower extremity muscle-tendon stiffness in male sprinters.
Methods: Seventeen male sprinters participated in the study and were randomly assigned to perform different interventions with 72-hour intervals. The interventions included 90% 1RM hip thrust (HT), 90% 1RM barbell half squat (HS), 30% 1RM HT + BFRT ( Blood Flow Restriction Training), and 30% 1RM HS + BFRT. Test content included 20-m sprint, vertical jump, rectus femoris pennation angle, and lower limb muscle-tendon stiffness. Descriptive statistics and Repeated measures ANOVA analysis were used for statistical analysis.
Results: (1) The study found that the 10-20m sprint performance was significantly improved compared to the 90%1RM HT and 90%1RM HS after the 30%1RM HS + BFRT interventions. Additionally, the 0-20m sprint performance was significantly improved than 90%1RMHS after 30%1RM HT + BFRT interventions; (2) The CMJ vertical jump height was significantly higher than the 90%1RM HS after the 30%1RM HS + BFRT intervention; (3) Moreover, the CMJ relative peak power was significantly increased after the 90%1RMHT and 90%1RMHS interventions compared to the 30%1RM HT + BFRT; The CMJ (Countermovement Jump) relative rate force development was significantly expanded after the 90%1RM HS intervention compared to the 30%1RM HT + BFRT. Furthermore, the 90% SJ (Squat Jump) relative rate force development after the 90%1RMHT intervention was significantly higher than the 30% 1RM HT + BFRT and 30% 1RM HS + BFRT. The CMJ relative peak force after the 90% 1RMHS intervention was significantly higher than the 30% 1RM HT + BFRT. Similarly, the SJ relative peak force after the 90% 1RMHT intervention was significantly higher than the 30% 1RM HT + BFRT and 30% 1RM HS + BFRT; (4) The study also found that the rectus femoris pennation angle was significantly lower after the 30%1RM HS + BFRT and 90%1RMHS practice interventions compared to after the 30%1RM HT + BFRT; (5) Additionally, therectus femoris muscle stiffness was significantly improved after the 30%1RM HT + BFRT compared to after the 30%1RM HS + BFRT. Moreover, the biceps femoris muscle stiffness was significantly increased after the 90%1RM HS intervention compared to after the 30%1RM HS + BFRT. The 90% 1RMHS and 30% 1RM HS + BFRT had significantly higher post-intervention gastrocnemius lateral stiffness than the 90% 1RM HT, and 30% 1RM HS + BFRT had significantly higher post-intervention gastrocnemius medial stiffness than 90%1RMHS, 30%1RM HT + BFRT.Lastly, the 30%1RM HS + BFRT had significantly increased post-intervention tibialis anterior stiffness than the 90% 1RM HT, and higher tibialis anterior stiffness after the 30% 1RM HS + BFRT intervention than 30% 1RM HT + BFRT. Additionally, there was a significantly improved Achilles tendon stiffness after the 30% 1RM HS + BFRT intervention compared to the 30% 1RM HT + BFRT.
Conclusions: (1) The study found that male sprinters experienced significant improvement in sprint performance after low-intensity barbell hip thrust resistance combined with blood flow restriction intervention compared to high-intensity barbell half-squat; (2) The positive effect of barbell half-squat exercise was significantly better than that barbell hip thrust on vertical jump performance; (3) Barbell half-squat exercise was found to have a significantly stronger positive effect than barbell hip thrust in decreasing the pennation angle of the rectus femoris muscle; (4) Both low-intensity barbell half squat and hip thrust exercises, when accompanied by blood flow restriction training intervention, were found to significantly improve lower extremity muscle-tendon stiffness.