Blood Flow Restriction Training: Understanding the Safety, Mechanisms, and Efficacy, 2nd Edition: Summary 9
THE SCIENCE BEHIND BFRT The two primary mechanisms thought to
Types of Blood Flow Restriction Training There are several ways BFRT can be applied: • Passive BFRT. This involves applying blood flow restriction without exercise, primarily to promote cell swelling and potentially improve tissue healing, such as after surgery. • BFRT during aerobic exercises (BFRT-AE) . This combines blood flow restriction with low-intensity aerobic activities like walking or cycling to improve aerobic capacity and muscle strength. • BFRT during resistive exercises (BFRT-RT) . This involves using blood flow restriction during low-load resistance training to improve muscle mass and muscle strength. All types of BFRT can potentially contribute to building muscle strength and mass, though BFRT-RT is typically most effective for this purpose. • Intermittent BFRT (I-BFRT). This approach involves alternating periods of blood flow restriction and normal blood flow, either during exercise or rest periods, commonly used for weight loss. Safety and Precautions While BFRT has been shown to be safe by many when applied correctly, including Odinesson & Finsen, 2006; Clark et al., 2011, and Poton & Polito, 2016, it is crucial to understand the proper application and potential risks. Some key safety considerations include: • Proper screening of patients for contraindications • Using the correct cuff pressure based on individual limb occlusion pressure (LOP): ○ Wider cuffs are generally safer as they require less pressure • Gradual progression of training intensity and duration • Monitoring for signs of excessive discomfort or adverse reactions
drive the benefits of BFRT are: 1. Metabolite-induced fatigue 2. Cell swelling
BFRT creates an environment of low oxygen availability, causing the activation of type II muscle fibers and anaerobic metabolism. This leads to a build-up of metabolites in the muscle, which stimulates several physiological changes required for muscle and bone strengthening. LEARNING TIP! The hypoxic (low oxygen)
environment created by BFRT, combined with the accumulation of metabolites, stimulates neural afferents. This causes a significant increase in growth hormone and other anabolic factors.
Studies have shown dramatic increases in growth hormone levels after BFRT sessions-one study reported a 290-fold increase compared to baseline. BFRT has been shown to affect several key physiological pathways and factors: • Increased activation of the mTOR pathway, which is crucial for protein synthesis and muscle growth • Increased levels of human growth hormone (HGH) • Increased insulin-like growth factor 1 (IGF-1) • Decreased levels of myostatin, a protein that normally limits muscle growth • Increased vascular endothelial growth factor (VEGF), which promotes the growth of new blood vessels Compared to traditional high-intensity resistance training, BFRT with low-load exercise produces similar or greater increases in these anabolic factors while causing minimal tissue damage. This allows for faster recovery and the potential for more frequent training sessions.
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