Hughes Systematic Review and Meta-Analysis 2017
March 17, 2017
Earlier this month, Luke Hughes et al. published a new systematic review and meta-analysis on Blood Flow Restriction in clinical musculoskeletal rehabilitation. In the study, the authors state “despite evidence of the effectiveness and tolerability of LL-BFR training in a clinical setting, various issues must be considered during implementation. Within the current literature, there is a lack of individualized prescription of BFR training. First, the occlusive pressure used is one aspect that should be individualized in the pursuit of safe and effective application. Research in healthy individuals has identified thigh circumference as an important predictor of occlusion pressure, with larger limbs requiring a higher pressure to reach the same level of occlusion as smaller limbs. A recent technique has emerged whereby calculation of total arterial limb occlusive pressure (LOP) allows for selection of a pressure at a percentage of LOP to standardize the level of occlusion across cohorts. This is used by the Association of Perioperative Registered Nurses to calculate required tourniquet pressures to restrict blood flow during surgery to minimize the risk of adverse events. LOP-based cuff pressures are lower than commonly used pressures but produce an effective surgical environment. Recent research employing this technique during BFR exercise demonstrated that higher LOP pressures are not required for greater facilitation of muscular responses to exercise compared with lower pressures.
The aim of this systematic review and meta-analysis was to synthesize the available information on the effects of and best parameters for BFR when being applied to a rehab based population. 8 studies met the inclusion criteria for the meta-analysis and 20 studies met the inclusion criteria for systematic review. “The results indicate that augmentation of low-load rehabilitative training with BFR can produce greater responses in strength compared with low-load training alone. At present, the strength gains appear to be smaller in magnitude to those achieved with heavy load training. However, LL-BFR training is a more effective alternative to low-load training alone and may act as a surrogate for heavy-load training. Thus, LL-BFR training may be used as a progressive clinical rehabilitation tool in the process of return to heavy-load exercise.”
There are other potential physiological adaptations to BFR. “In older adults who are increasingly susceptible to sarcopenia, LL-BFR training was shown to stimulate mTORC1 signaling and muscle protein synthesis in older men. Research has demonstrated increased serum concentrations of bone alkaline phosphatase and increased bone turnover following 6 weeks of LL-BFR training, suggesting an impact on bone health. Low-load walk training with BFR has been demonstrated to increase knee extensor and flexor torque, carotid arterial compliance, peak oxygen uptake, peak post-occlusive blood flow and vascular endothelial function and peripheral nerve circulation in older individuals. LL-BFR training can attenuate the effects of sarcopenia and may be effective at improving bone health.”
This study helps to support the need to individualize occlusion pressures not only for the safety of our patients and clients but also for the objectivity of future research.