Centner et al. (2018) Effects of Blood Flow Restriction Training on Muscular Strength and Hypertrophy in Older Individuals – A Systematic Review and Meta-Analysis
Occlusion training aka. Blood Flow Restriction Training (BFRT) or just Blood Flow Restriction (BFR) – is partial restriction of blood flow not actual occlusion!
The concept is known under several different terms but originates from 1970s Japan, where it is called Kaatsu training. It is primarily an alternative or supplement to conventional resistance training and musculoskeletal rehabilitation.
Traditionally the recommendation for resistance training is to use a load that is at least 60%, of what you can lift once (60% of 1RM). However, various research articles shows that low load exercise augmented by BFR is just as beneficial as conventional resistance training!
In BFR training, the venous out-flow of blood is restricted, thus allowing for arterial in-flow in such a way that blood supply is only partly restricted to the working muscles. This enables low-load exercise to stimulate the muscles to become stronger, larger and more persistent, comparable to conventional strength training.
By using partial occlusion, muscles undergo rapid fatigue even at relative light intensities regardless of exercise type. When the blood flow is partially restricted, metabolites accumulates and the metabolic requirements increases which causes a cascade of physiological processes. In practice, you will experience it as rapid fatigue of the working muscles, an intense pumping sensation.
The different pathways for muscle growth (hypertrophy) is shown in this simplified model, with the most important factors at the bottom. An explanation of why BFR is so effective eliciting hypertrophy is that 2 out of 3 pathways can be identified.
Effect Size – Explained
There are many ways to compare the effect of occlusion training (BFR) vs. conventional resistance training (CRT) and this results in varying conclusions of wherever BFR is more or less effective.
Short-term muscle mass: Probably BFR
Long-term muscle mass: Approximately same
Short-term muscle strength: Approximately same
Long-term muscle strength: Probably CRT
Muscle endurance: BFR
Maximum power development (RFD) and training to improve running velocity: CRT
Slysz et al. (2016) – The efficacy of blood flow restricted exercise A systematic review & meta-analysis
Scott et al. (2016) – Blood flow restricted exercise for athletes: A review of available evidence
Comparison with weight or load restrictions (injury or impaired)
Short-term muscle mass – (BFR)
Long-term muscle mass – (BFR)
Short-term muscle strength – (BFR)
Long-term muscle strength – (BFR)
Muscle endurance – (BFR)
Maximum power development – (Often not possible in early rehab)
Hughes et al. (2017) – Blood flow restriction training in clinical musculoskeletal rehabilitation in systematic review and meta-analysis
In summary there are evidence for occlusion training has both advantages and less disadvantages!
BFR Exercise has many positive effects:
Treatment of sarcopenia by increasing muscle mass (protective for a wide range of age-related issues and chronic conditions (How When & Why Occlusion Training)
- Greater muscle strength – directly transferable to everyday activities (ADL) Fall prevention
- Improved circuit function
- Better self-reported health
- Shorter training time
- Shorter restitution time
- Alternative or supplement to heavy training during the season (due to less mechanical strain)
- Use during periodization training with a focus on high rep / low-load
Occlusion training combined with moderate heavy training Link for scientific paper – ncbi.nlm.nih.gov
- Ischemic preconditioning Link – ischemic preconditioning – youtube
Therefore, occlusion training can be relevant for everyone from the top athlete to the seniors!
Nerd-Alert – The adaptive muscle response
The partial restriction of blood flow in combination with muscles contractions creates a short-term edema (cell swelling) around the muscle cells which limits the supply of oxygen and nutrients so that metabolites accumulates (Cayot et al., 2014). This initiates a cascade of physiologic process, like the increase of growth hormone secretion, as approximately 2-3 fold greater compared to conventional resistance training. But also the increased activation of muscle satellite cells, about two fold larger than than conventional resistance training. This upregulates the net protein synthesis.(Yasuda et al., 2014; Segal et al., 2010; Roos and Lohmander 2003).
↑ Muscle oxygenation – hypoxia leading to short term ischemia
↑ Metabolite accumulation – accumulation of waste products
↑ Recruiting fast twice muscle fibers
↑ Cell Swelling
↑ Growth hormone 200-300% of conventional strength training – relevant for bone and tendon health
↑ Satellite cell proliferation
↓ Secretion of muscle growth inhibitors (myostatin) – especially important for building muscle tissue
↑ Netto protein synthesis = Hypertrophy (muscle growth)
↑ Muscle strength and endurance
↓ Metabolic resistance – relevant to metabolic syndrome and diabetise
↑ Anaerobic threshold
↑ Mitochondrial content
These processes are further described in the scientific literature, especially by the leading researcher in the field of Associate Professor Jeremy P. Loenneke as he is attributed to a large part of the accumulated knowledge. For the past 10 years, he has published scientific articles on the underlying mechanisms and effects of occlusion training or Blood Flow Restriction.
Overall there are published more than 300 scientific studies across all continents, which demonstrates the effect of occlusion training.