Effects of Blood Flow Restriction Resistance Exercise Versus Traditional Resistance Exercise in Voluntary Exhaustion on Quadriceps Muscle Adaptations in Untrained Young Males: A Randomized Trial

<i>Background and Objectives:</i> This study compared the effects of blood flow restriction resistance exercise (BFR-RE) and high-load resistance exercise (HL-RE) in voluntary exhaustion on quadriceps muscle adaptations in untrained young males. <i>Materials and Methods:</i> This study used a randomized controlled design that included 30 untrained young males (age = 21.42 ± 2.51). The BFR-RE group performed leg extension exercises with 60% occlusion pressure and 30% of one maximum repetition in volitional exhaustion. The same exercise was conducted at 70% 1RM in the HL-RE group. Fourteen variables were used to evaluate the intervention efficacy, including muscle thickness, stiffness, strength, cross-sectional area (CSA), and subcutaneous fat thickness. Analyses were reported using frequentist and Bayesian approaches. The Bayes factor (BF10 and BFincl) was interpreted based on negative and positive values. <i>Results:</i> The results revealed that the main effect of time was statistically significant for muscle strength, thickness, CSA, and stiffness (<i>p</i> < 0.05, BFincl > 1) and, in intragroup comparisons, both groups showed improvements in these parameters (<i>p</i> < 0.05, BF10 > 1). A statistically significant decrease in subcutaneous fat thickness was observed in the BFR-RE group (<i>p</i> < 0.05, BF10 > 1), while this change was not observed in the HL-RE group (<i>p</i> > 0.05, BF10 < 1). Similarly, a statistically significant increase in right rectus femoris muscle stiffness was detected in the BFR-RE group (<i>p</i> < 0.05, BF10 > 1) but not in the HL-RE group (<i>p</i> > 0.05, BF10 < 1). Furthermore, time's main effect was statistically insignificant for thigh circumference (<i>p</i> > 0.05, BFincl < 1). The group × time interaction was statistically significant only for peak power leg flexion left (<i>p</i> < 0.05, BFincl > 1), and a statistically significant difference in favor of the BFR-RE group was observed in the intergroup comparisons (<i>p</i> < 0.05, BF10 > 1). <i>Conclusions:</i> In conclusion, BF-RE exercise with voluntary exhaustion may be as effective as HL-RE for hypertrophic adaptations in untrained young males.