Can you build serious strength without heavy weights? A clinical trial comparing resistance training and blood flow restriction methods highlights options for those seeking gains without joint stress.
Study: Comparative analysis of high-intensity resistance training and blood flow restriction training on enhancing upper limb muscle strength and mass. Image credit: Ground Picture/Shutterstock.com
A recent paper published in the journal Frontiers in Physiology compares the effects of two types of exercise training on upper limb muscle mass and strength. The results could help redirect people unsuitable for high-intensity training to another alternative.
Introduction
High-intensity resistance training (HIRT) is an effective way to achieve upper limb muscle growth, but at a higher risk of damaging the joints, ligaments, or tendons in this injury-prone area. Low-intensity training uses a low training load with more repetitions, increasing the time required. Though it is safer than HIRT, it is also less effective, reducing the final muscle hypertrophy.
Blood Flow Restriction Training (BFRT) is a low-intensity alternative to HIRT. Also known as KAATSU training, BFRT is a novel method of strength training in which external pressure is applied to the limbs using specially designed pressure equipment. This pressure obstructs venous blood flow completely and arterial flow partly. The outcome is more intense body stimulation at each load level, the goal being to increase muscle strength and size and boost endurance.
BFRT could be a safe middle path that confers muscle growth and strength comparable to that with HIRT, but with less risk of injury. BFRT combined with short-term intensive strength training improved body composition and cardiac performance, enhancing cardiovascular fitness. This is the case in young and elderly participants after a short-term intervention.
BFRT has also been demonstrated in the rehabilitation of post-surgical patients, for instance, after anterior cruciate ligament reconstruction. Here, it improves muscle thickness and strength, helping the patient regain function. BFRT also prevents injury in older adults by increasing bone strength and exercise capacity.
BFRT can be optimized by using an exercise intensity of 20% to 40% of one-repetition maximum strength (1RM) with a high number of repetitions, during two or three sessions per week. Pressure is applied to achieve 50% to 80% vessel blockade, though there is no consensus on whether to use absolute vs progressive pressure. Each of these affects upper limb training adaptation, but they have not been directly compared with each other or with HIRT, prompting the research in the current study.
This study was a randomized controlled trial involving 34 participants, who were randomly assigned to one of three groups: the HIRT, BRTF with fixed pressure (BFRT-F), or BFRT with progressive pressure (BFRT-P).
Study findings
The 1RM increased significantly in all groups, with the best results in the HIRT group, followed by the BFRT-P group.
The HIRT protocol increased all isokinetic muscle strength parameters. The highest was an increase of over 55% in the triceps extension. Peak torque increased significantly at the shoulder and elbow joints in the HIRT group compared with BFRT-F.
The BFRT-P group experienced comparable increases in strength of between 30% and 40%. Though increases occurred in the BFRT-F group, the gains were significantly below those in the other groups. With the trunk and back muscle groups, the gains in peak torque were highest for HIRT (~3%) compared to both other groups. Still, the BFRT-P group showed a marked improvement in peak torque compared to BFRT-F.
Despite being inferior to the other groups' outcomes, the BFRT-F also showed significantly higher peak torque in several joint extensors and flexors.
The HIRT and BFRT-P groups, but not the BFRT-F group, demonstrated increased arm muscle circumference, especially during muscle contraction, signaling muscle hypertrophy. The most significant increase occurred in the HIRT group.
Muscle mass increased in both the HIRT and BFRT-P groups. In the HIRT group, this increase was about 15.1% and 22.6% in the left and right arms, respectively, and 5.2% and 10.6% in the BFRT-P group, for the left and right arms, respectively. The BFRT-F group failed to show any significant change.
These findings followed the predicted pattern, probably because progressive pressure with BFRT-P causes greater metabolic stress. This, in turn, induces more hypoxia and results in the accumulation of metabolites in the muscle, the probable reason for its superiority to BFRT-F.
Conclusion
The study presents the first direct and controlled comparison of high-intensity resistance training with two blood flow restriction training modalities. It demonstrated that the best results were obtained with HIRT, confirming, as expected, “HIRT’s role as the gold standard for mechanical tension-driven adaptations”. In contrast, the BFRT-F group had the lowest gains.
Notably, the BFRT-F group used a lower load at 30% 1RM but still showed strength gains, indicating that BFRT does play a role in improving strength. Certain studies suggest that BFRT can build muscle strength comparably to HIRT, but possibly only in trained individuals. BFRT may be especially important in training among older men, where it has sometimes been shown to be nearly as effective as HIRT, though the results are conflicting.
The authors noted that using fixed, absolute pressures instead of individualized arterial occlusion pressures may have limited BFRT’s full potential. They also acknowledge the absence of a low-intensity resistance training group with BFRT, which limits comparisons between BFRT and conventional low-load training. Additionally, muscle strength was estimated using an indirect 1RM formula rather than measured directly, introducing possible error.
“While HIRT is optimal for strength and hypertrophy, BFRT-P is a viable alternative for individuals contraindicated to high-intensity training.” The findings suggest that pressure progression may be crucial in maximizing results with BFRT. Future studies should explore the role of personalized arterial occlusion pressures and include a low-intensity control group to provide controls for low-load training without the effect of BFRT.
Download your PDF copy now!
Blood and urine tests reveal how much ultra-processed food you really eat, study finds