Safety and efficacy of blood flow restriction exercise in individuals with neurological disorders: A systematic review

The effects of blood flow restriction combined with low-intensity resistance training on muscle strength and pain during postoperative recovery in patients with knee injuries: a meta-analysis

To investigate the effects of low-load blood flow restriction training (LL-BFRT) on muscle strength and pain during postoperative rehabilitation in patients with knee injuries. A systematic review and meta-analysis was conducted in accordance with PRISMA guidelines. Comprehensive searches through PubMed, EBSCO, Cochrane, Web of Science, and Embase yielded 1049 articles, of which 13 studies met the inclusion criteria. Quantitative analyses were performed using Review Manager 5.3 and Stata. LL-BFRT showed a significant positive effect on muscle strength, with a standardized mean difference (SMD) of 0.70 (p < 0.00001, 95%CI: 0.49, 0.92, I2 = 42%, p = 0.07). In terms of pain reduction, LL-BFRT significantly lowered the outcome of visual analog scale (VAS), with an SMD of -0.60 (p < 0.00001, 95% CI: -0.85, -0.36, I2 = 0%, p = 0.44). LL-BFRT effectively improves muscle strength and reduces pain in patients recovering from knee injuries postoperatively. It presents an alternative rehabilitation method for patients who are unable to perform high-intensity resistance training.

Efficacy and acceptability of different blood flow restriction training interventions during the rehabilitation of military personnel with lower limb musculoskeletal injuries: protocol for a two-phase randomised controlled trial

BACKGROUND

Musculoskeletal injury (MSKI) is the leading cause of medical downgrading and discharge within the UK military, with lower limb MSKI having the greatest incidence, negatively impacting operational readiness. Pain is a primary limiting factor to rehabilitation progress following MSKI. Heavy-load resistance training (RT; ie, loads >70% 1-repetition maximum) is traditionally used but may be contraindicated due to pain, potentially prolonging recovery and leading to failure of essential physical employment standards for UK military personnel. Low-load RT with blood flow restriction (BFR) can promote favourable morphological and physiological adaption, as well as elicit hypoalgesia in healthy and clinical populations (eg, post-operative), and has proven a viable option in military rehabilitation settings. The acceptability and tolerance of higher relative BFR pressures in persistent pain populations are unknown due to the complexity of presentation and the perception of discomfort experienced during BFR exercise. Greater relative pressures (ie, 80% limb occlusion pressure (LOP)) elicit a greater hypoalgesic response in pain-free individuals, but greater perceived discomfort which may not be tolerated in persistent pain populations. However, lower relative pressure (ie, 40% LOP) has elicited hypoalgesia in pain-free individuals, which therefore may be more clinically acceptable and tolerated in persistent pain populations. The primary aim of both randomised controlled trials (RCT) is to investigate the efficacy and acceptability of using high-frequency, low-load BFR-RT in UK military personnel with lower limb MSKI where persistent pain is the primary limiting factor for progression.

METHODOLOGY

The presented protocol is a two-phase RCT based within a military rehabilitation setting. Phase One is a 1-week RCT to determine the most efficacious and acceptable BFR-RT protocol (7× BFR-RT sessions over 5 days at 40% or 80% LOP; n=28). Phase Two is a 3-week RCT comparing the most clinically acceptable BFR pressure, determined by Phase One (21× BFR-RT sessions over 15 days; n=26) to usual care within UK Defence Rehabilitation residential rehabilitation practices. Outcomes will be recorded at baseline, daily and following completion of the intervention. The primary outcome will be the brief pain inventory. Secondary outcomes include blood biomarkers for inflammation and pain (Phase Two only), injury-specific outcome measures, lower extremity function scale, objective measures of muscle strength and neuromuscular performance, and pressure pain threshold testing.

ETHICS AND DISSEMINATION

The study is approved by the Ministry of Defence Research Ethics Committee (2318/MODREC/24) and Northumbria University. All study findings will be published in scientific peer-reviewed journals and presented at relevant scientific conferences.

TRIAL REGISTRATION NUMBER

Registered with Clinical Trials. The registration numbers are as follows: NCT06621914 (Phase One) and NCT06621953 (Phase Two).

Mechanisms of muscle repair after peripheral nerve injury by electrical stimulation combined with blood flow restriction training

This review elucidates the impact of electrical stimulation (ES) and blood flow restriction (BFR) training on muscle function. ES induces a transformation in muscle fibers type by rearranging myosin heavy chain isoform patterns. Additionally, it influences muscle protein synthesis and degradation through specific signaling pathways such as protein kinase B/mechanistic target of rapamycin (Akt/mTOR), as well as via autophagy and the ubiquitin-proteasome system, thereby effectively maintaining muscle mass. BFR, on the other hand, restricts muscle blood flow, leading to metabolic products accumulation and localized hypoxia, which not only promotes the recruitment of fast-twitch fibers but also activates the mTOR signaling pathway, enhancing muscle protein synthesis. The combination of ES and BFR synergistically facilitates muscle protein synthesis through the mTOR pathway, thereby accelerating the recovery of muscle function following peripheral nerve injury.

Efficacy of Blood Flow Restriction Exercise for Improving Lower Limb Muscle Strength and Function in Chronic Spinal Cord Injury: A Randomized Controlled Trial

The objective of the present study was to evaluate the efficacy of low-load (LL) blood flow restriction exercise (BFRE) for improving lower limb muscle strength, muscle thickness and physical function in individuals with spinal cord injury (SCI). In a randomized sham-controlled trial, 21 participants (age ≥ 18 years, SCI duration ≥ 1 year, knee extensor strength grade 2-4, ASIA A-D) were randomized to either 45-min LL-BFRE (n = 11) or sham BFRE (n = 10) twice/week for 8 weeks. The exercise protocol consisted of four sets (30 × 15 × 15 × 15 repetitions) of unilateral seated leg extensions and leg curls at 30%-40% of 1RM performed with pneumatic cuffs applied proximally on the trained limb and inflated to 40% of total arterial occlusion pressure (BFRE) or non-inflated (sham exercise). Maximal voluntary isometric quadriceps and hamstring muscle strength, quadriceps muscle thickness, thigh circumference, and physical function were assessed at baseline, after 4 and 8 weeks of training and at 4-week follow-up. No significant between-group differences were found between BFRE and sham exercise in quadriceps or hamstring muscle strength, 10-m walking test, timed up & go, 6-min walking test or the spinal cord independence measure. In contrast, a significant between-group difference favoring BFRE was present for muscle thickness and thigh circumference from baseline to 4-week follow-up (0.76 cm (95% CI: 0.32; 1.20, p = 0.002) and 2.42 cm (0.05; 4.79, p = 0.05), respectively). In conclusion, there was no significant difference in the effect of LL-BFRE and sham exercise on muscle strength and physical function in individuals with SCI. However, significant increases in muscle thickness and thigh circumference were observed in favor of BFRE. Trial Registration: ClinicalTrials.gov identifier: NCT03690700.

Effectiveness and Feasibility of Blood Flow Restriction Training for People with Multiple Sclerosis: A Systematic Review

BACKGROUND

Multiple sclerosis (MS) is an immune-mediated inflammatory disease that primarily targets the myelin of axons. Extremities are frequently affected, resulting in a negative impact on both activities of daily living (ADL) and quality of life. In recent years, there has been increasing interest in the potential benefits of exercise and blood flow restriction training (BFRT) programs as a therapeutic tool in people with neurological disorders. The aim of the present systematic review was to know the clinical effects of BFRT programs in people with MS.

METHODS

A systematically comprehensive literature search was conducted and registered in PROSPERO prior to its execution under the reference number CRD42024588963. The following data sources were used: Pubmed, Scopus, Web of Science (WOS) and the Cochrane Library. The following data were extracted from the papers: study design, sample, interventions, dosage, outcome measures and results. To assess the methodological quality of the papers included, the Quality Index of Downs and Black was used. Additionally, the articles were classified according to the levels of evidence and grades of recommendation for diagnosis studies established by the Oxford Center for Evidence-Based Medicine. Also, the Cochrane Handbook for Systematic Reviews of Interventions was used by two independent reviewers to assess risk of bias, assessing the six different domains.

RESULTS

Seven articles with a total of 71 participants were included in the review. Of the seven articles, five papers studied the effectiveness of BFRT combined with strengthening exercises and two papers studied the effect of BFRT combined with aerobic exercise. Of the five articles that analyzed BFRT combined with strengthening exercises, only two presented a control group. Both performed a low-load resistance training in combination with BFRT with four series, 30/15/15/15 repetitions and a rest of 1 min between the series and 3 min between the exercises. The control groups to which they were compared performed a high intensity strengthening exercise protocol which had the same exercises, sets, rests and duration of the protocol as the experimental groups. For those two papers which investigated the effects of BFRT combined with aerobic training, exercise was performed in two sessions per week for a period of 8 and 6 weeks, respectively. In both studies, the experimental protocol began with a warm-up phase and ended with a cool-down phase, and there were differences in cuff management. All these investigations found positive effects in the interventions that combined exercise with BFRT. The characteristics, outcome measures, effects of the interventions and the assessment of the methodological quality of the included studies and risk of bias are shown in the tables.

CONCLUSIONS

BFRT in people with MS appears to be effective and safe for people with MS. BFRT might show positive clinical effects on strength, hypertrophy and balance outcomes. Nevertheless, future research should be conducted with better methodological quality to ensure the potential benefits of BFRT in people with MS since the studies analyzed present a high risk of bias and methodological limitations.

Feasibility and safety of two weeks of blood flow restriction exercise in individuals with spinal cord injury

CONTEXT

Reduced muscle strength and function are common after spinal cord injury (SCI). While low-load blood flow restriction exercise (BFRE) enhances muscle strength in healthy and clinical populations, its safety and feasibility in individuals with SCI remain underexplored.

OBJECTIVES

To investigate the feasibility and safety of low-load BFRE in individuals with incomplete SCI.

STUDY DESIGN

Case series.

SETTING

SCI rehabilitation center.

PARTICIPANTS

Six participants with motor incomplete SCI were enrolled in the study.

INTERVENTION

A two-week BFRE intervention for the lower limbs was conducted twice weekly at 40% total arterial occlusion pressure, using 30-40% of 1-repetition maximum loads.

OUTCOME MEASURES

Feasibility measures, specifically recruitment and eligibility rates and intervention acceptability, were collected. Blood pressure (BP) responses and specific coagulation markers for deep vein thrombosis (DVT) were assessed as safety measures.

RESULTS

Recruitment and eligibility rates were 2.8% and 6.6% for individuals admitted for first-time rehabilitation (subacute SCI) and 8.3% and 13.9% for 4-week readmission rehabilitation stays (chronic SCI), respectively. Intervention acceptability was high, characterized by 95.8% training adherence and low-to-moderate self-reported pain levels. BP responses and changes in C-reactive protein, Fibrinogen, and D-dimer during the intervention remained within clinically acceptable levels.

CONCLUSION

BFRE was feasible in an SCI rehabilitation setting despite a low recruitment rate. BFRE imposed no heightened risk of DVT or severe BP fluctuations in the present case series. Additionally, no severe adverse events occurred, and only mild complaints were reported. More extensive safety considerations warrant larger-scale exploration.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT03690700.

The Effect of Blood Flow Restriction during Low-Load Resistance Training Unit on Knee Flexor Muscle Fatigue in Recreational Athletes: A Randomized Double-Blinded Placebo-Controlled Pilot Study

Background/Objectives: Despite the growing popularity of training with a controlled form of vascular occlusion, known as blood flow restriction (BFR) training, in the rehabilitation of orthopedic patients and sports medicine, there remains ample space for understanding the basis of its mechanism. The pilot study assessed the effect of BFR during a low-load resistance training unit on knee flexor muscle fatigue, intending to decide whether a larger trial is needed and feasible. Methods: The study used a prospective, randomized, parallel, double-blind, placebo-controlled design. Fifteen male healthy recreational athletes were randomly assigned to three equal groups: BFR Group, Placebo Group, and Control Group. The primary outcome was the change in the surface electromyography-based (sEMG-based) muscle fatigue index, which was determined by comparing the results obtained before and after the intervention. The intervention was the application of BFR during low-load resistance training for knee flexors. The occurrence of any adverse events was documented. Results: In all groups, the sEMG-based fatigue index for semitendinosus and biceps femoris muscles decreased after low-load resistance training, with the largest decrease in the BFR group. Although not statistically significant, BFR showed moderate and large effect sizes for the fatigue index of semitendinosus and biceps femoris, respectively. No adverse events were noted. Conclusions: The pilot study suggested that BFR during a low-load resistance training unit might affect knee flexor muscle fatigue, supporting the development of a larger randomized clinical trial.