Blood Flow Restriction Resistance Exercise as a Rehabilitation Modality Following Orthopaedic Surgery: A Review of Venous Thromboembolism Risk

Vascular occlusion for optimising the functional improvement in patients with knee osteoarthritis: a randomised controlled trial

OBJECTIVES

Knee osteoarthritis (KOA) is a leading cause of global disability with conventional exercise yielding only modest improvements. Here we aimed to investigate the benefits of integrating blood flow restriction (BFR) into traditional exercise programmes to enhance treatment outcomes.

METHODS

The Vascular Occlusion for optimizing the Functional Improvement in patients with Knee Osteoarthritis randomised controlled trial enrolled 120 patients with KOA at Ghent University Hospital, randomly assigning them to either a traditional exercise programme or a BFR-enhanced programme over 24 sessions in 12 weeks. Assessments were conducted at baseline, 6 weeks, 12 weeks and 3 months postintervention using linear mixed models with Dunn-Sidak corrections for multiple comparisons. Primary outcome was the Knee injury and Osteoarthritis Outcome Score (KOOS) questionnaire at 3 months follow-up with knee strength, Pain Catastrophizing Scale questionnaire and functional tests as secondary outcomes. Analysis followed an intention-to-treat approach (NCT04996680).

RESULTS

The BFR group showed greater improvements in KOOS pain subscale (effect size (ES)=0.58; p=0.0009), quadriceps strength (ES=0.81; p<0.0001) and functional tests compared with the control group at 12 weeks. At 3 months follow-up, the BFR group continued to exhibit superior improvements in KOOS pain (ES=0.55; p=0.0008), symptoms (ES=0.59; p=0.0004) and quality of life (QoL) (ES=0.66; p=0.0001) with sustained benefits in secondary outcomes. Drop-out rates were similar in both groups.

CONCLUSION

Incorporating BFR into traditional exercise programmes significantly enhances short-term and long-term outcomes for patients with KOA demonstrating persistent improvements in pain, symptoms, QoL and functional measures compared with conventional exercise alone. These findings suggest that BFR can provide the metabolic stimulus needed to achieve muscle strength and functional gains with lower mechanical loads. Reduced pain and increased strength support a more active lifestyle, potentially maintaining muscle mass, functionality and QoL even beyond the supervised intervention period.

TRIAL REGISTRATION NUMBER

NCT04996680.

Effect of muscle strength on deep vein thrombosis: A Mendelian randomization study

Deep vein thrombosis (DVT) is a serious condition characterized by blood clots in deep veins, posing a significant public health burden. Muscle strength has been implicated as a potential risk factor for DVT due to its influence on venous return. This study aims to investigate the causal association between muscle strength and DVT using a Mendelian randomization (MR) approach, leveraging genetic variants as instrumental variables (IVs). We conducted a 2-sample MR analysis using genome-wide association study (GWAS) data for hand-grip strength and DVT. IVs were selected based on their significant associations with muscle strength and DVT, as well as their linkage disequilibrium patterns. We employed statistical methods including inverse-variance weighting (IVW), MR-Egger, and weighted median to address pleiotropy bias. Sensitivity analyses were conducted to evaluate the robustness of the results. A total of 21 and 14 independent IVs were identified for hand grip strength (EWGSOP) and hand grip strength (FNIH), respectively. IVW analysis revealed a consistent causal and negative association between both definitions of hand grip strength and DVT (EWGSOP: OR = 0.702, 95% CI: 0.511-0.964, P = .029; FNIH: OR = 0.715, 95% CI: 0.570-0.898, P = .004). No directional pleiotropy was detected in MR-Egger and MR-PRESSO analyses for either definition (EWGSOP: MR-Egger Intercept P = .516; MR-PRESSO global test P = .162; FNIH: MR-Egger Intercept P = .569; MR-PRESSO global test P = .371).Sensitivity analyses demonstrated the stability of the causal effect estimates, with little influence from individual IVs. The MR analysis provided evidence of a causal association between muscle strength and DVT risk, suggesting that increasing muscle strength may have a protective effect. These findings have implications for preventive strategies and the promotion of resistance exercises and muscle-strengthening activities. Further research and validation of these results could inform clinical guidelines and interventions for DVT prevention.

The Effect of Blood Flow Restriction Exercise Prior to Total Knee Arthroplasty on Postoperative Physical Function, Lower Limb Strength and Patient-Reported Outcomes: A Randomized Controlled Trial

The trial aimed to examine the effect of eight weeks preoperative low-load blood flow restricted resistance training (BFR-RT) on physical function, lower limb strength, and patient-reported outcomes in knee OA patients 3 and 12 months after total knee arthroplasty (TKA) compared with preoperative usual care. An assessor blinded randomized controlled trial (RCT) was conducted. Eighty-six patients scheduled for TKA who were allocated to 8 weeks BFR-RT on the affected leg 3x/week or preoperative usual care involving no exercise (CON).

PRIMARY OUTCOME

30-s sit to stand (30STS).

SECONDARY OUTCOMES

Timed Up&Go, 40-m walk test (40mWT), knee range of motion (ROM) 1-repetition maximum (1RM) leg press and knee extensor strength, maximal isometric contraction (MVIC) for the knee extensors and flexors, Knee injury and Osteoarthritis Outcome Score (KOOS), and Euroqol 5-dimensions (EQ-5D-L5) questionnaire. Data were collected at baseline (12 weeks pre-surgery), ~3 days pre-surgery, 3 and 12 months postoperatively. Intention-to-treat analysis revealed no significant between-group differences in the change from baseline to 3 and 12 months postoperatively on 30STS, TUG, or 40mFWT. Significant between-group differences were observed at 3 but not 12 months postoperatively for the corresponding changes in 1RM leg press strength, 1RM knee extensor strength, and MVIC knee extensor favoring BFR-RT. No between-group differences were observed for the delta changes from baseline in knee ROM, KOOS subscales or EQ-5D-L5 at any postoperative time points. These findings suggest that preoperative BFR-RT offered no superior effects compared with usual preoperative care on postoperative physical function or patient-reported outcomes. Preoperative BFR-RT produced amplified gains in lower limb muscle strength at 3 months postoperatively.

TRIAL REGISTRATION

NCT04081493.

The Acute and Chronic Effects of Resistance and Aerobic Exercise in Hemostatic Balance: A Brief Review

Hemostatic balance refers to the dynamic balance between blood clot formation (coagulation), blood clot dissolution (fibrinolysis), anticoagulation, and innate immunity. Although regular habitual exercise may lower the incidence of cardiovascular diseases (CVD) by improving an individual’s hemostatic profile at rest and during exertion, vigorous exercise may increase the risk of sudden cardiac death and venous thromboembolism (VTE). This literature review aims to investigate the hemostatic system’s acute and chronic adaptive responses to different types of exercise in healthy and patient populations. Compared to athletes, sedentary healthy individuals demonstrate similar post-exercise responses in platelet function and coagulatory and fibrinolytic potential. However, hemostatic adaptations of patients with chronic diseases in regular training is a promising field. Despite the increased risk of thrombotic events during an acute bout of vigorous exercise, regular exposure to high-intensity exercise might desensitize exercise-induced platelet aggregation, moderate coagulatory parameters, and up-regulate fibrinolytic potential via increasing tissue plasminogen activator (tPA) and decreasing plasminogen activator inhibitor (PAI-1) response. Future research might focus on combining different types of exercise, manipulating each training characteristic (frequency, intensity, time, and volume), or investigating the minimal exercise dosage required to maintain hemostatic balance, especially in patients with various health conditions.

The effectiveness and safety of blood flow restriction training for the post-operation treatment of distal radius fracture

INTRODUCTION

Distal radius fracture (DRF) is a common injury in the upper extremities. Blood flow restriction (BFR) has been proven to be effective in improving function in low-load training, which is suitable for post-op rehabilitation. We explored the effectiveness and safety of BFR therapy in DRF patients who underwent surgery.

MATERIALS AND METHODS

Thirty-five patients were randomly assigned to either the BFR or the regular training (RT; no BFR therapy) groups. All patients completed the same 4-week postoperative rehabilitation program, including anti-inflammatory treatments, strengthening and range of motion (ROM) training. In the BFR group, the pressure was 120 mmHg in strengthening training course. Pain, circumferences of wrists and forearms, ROM, muscle strength, and D-dimer levels were evaluated at weeks 0, 2, and 4. Radius union scoring system (RUSS) was measured at weeks 4 and 12. Finally, wrist functionality (Cooney modification) was evaluated at week 12.

RESULTS

The BFR group had significantly decreased pain levels compared with the RT group (p < 0.01, effect size= 2.33, -2.44 at weeks 2 and 4). Swelling was effectively relieved in both groups. The wrist swelling was less in the BFR group (p < 0.01, effect size = -2.17 at week 4). The isometric strength of wrist extension (p < 0.01, effect size = 1.5, 3.02 at weeks 2 and 4), flexion (p < 0.01, effect size = 1.33, 2.53 at weeks 2 and 4), and functionality significantly increased in the BFR group (p < 0.01, effect size = 2.80 at week 12). No risk of VT in the BFR group was found. BFR did not threaten bone healing.

CONCLUSIONS

In patients with DRF who underwent corrective surgery, BFR therapy effectively relieved pain and swelling, increased muscle strength and wrist function, and had no additional risks for bone healing and VT.

Application and progress of blood flow restriction training in improving muscle mass and strength in the elderly

As an emerging training method, blood flow restriction training has been proved to promote the growth of muscle mass and strength. In recent years, it has been gradually applied in different populations. However, there are few studies on how blood flow restriction training affects muscle mass and strength in the elderly. The relevant literature is compiled and summarized in this study. Through the comparison of blood flow restriction training with traditional training methods and its application in the elderly, it shows that blood flow restriction training can effectively increase muscle mass and strength, prevent muscle atrophy, improve cardiopulmonary function, facilitate injury and postoperative rehabilitation, and intervene in related degenerative diseases as a training method suitable for the elderly,. The main mechanism of blood flow restriction training promoting muscle mass and strength growth is metabolic stress response, including muscle fiber recruitment, protein synthesis signal pathway activation, hormone secretion, etc., and is also related to cell swelling caused by pressure. At present, although the application of blood flow restriction training in the elderly population is increasing, there is a lack of personalized programs. In the future, more research on the dose effect and safety of blood flow restriction training is needed to develop more accurate personalized training programs.

Effects of Blood Flow Restriction Therapy for Muscular Strength, Hypertrophy, and Endurance in Healthy and Special Populations: A Systematic Review and Meta-Analysis

OBJECTIVES

Blood flow restriction (BFR) training is an increasingly applied tool with potential benefits in muscular hypertrophy, strength, and endurance. This study investigates the effectiveness of BFR training relative to other forms of training on muscle strength, hypertrophy, and endurance.

DATA SOURCES

We performed systematic searches of MEDLINE, Embase, and PubMed and assessed the methodological quality of included studies using the Cochrane risk of bias tool.

MAIN RESULTS

We included 53 randomized controlled trials with 31 included in meta-analyses. For muscular strength comparing low-intensity BFR (LI-BFR) training with high-intensity resistance training (HIRT), the pooled mean difference (MD) for 1 repetition maximum was 5.34 kg (95% CI, 2.58-8.09; P < 0.01) favoring HIRT. When comparing LI-BFR training with HIRT for torque, the MD was 6.35 N·m (95% CI, 0.5-12.3; P = 0.04) also favoring HIRT. However, comparing LI-BFR with low-intensity resistance training (LIRT) for torque, there was a MD of 9.94 N·m (95% CI, 5.43-14.45; P < 0.01) favoring BFR training. Assessing muscle hypertrophy, the MD in cross-sectional area was 0.96 cm2 (95% CI, 0.21-1.7; P = 0.01) favoring pooled BFR training compared with nonocclusive training. Assessing endurance, V̇o2 maximum demonstrated a greater mean increase of 0.37 mL/kg/min (95% CI, -0.97 to 3.17; P = 0.64) in BFR endurance training compared with endurance training alone.

CONCLUSION

Blood flow restriction training produced increases in muscular strength, hypertrophy, and endurance. Comparing LI-BFR training with HIRT, HIRT was a significantly better training modality for increasing muscle hypertrophy and strength. However, LI-BFR was superior when compared with a similar low-intensity protocol. Blood flow restriction training is potentially beneficial to those unable to tolerate the high loads of HIRT; however, better understanding of its risk to benefit ratio is needed before clinical application.

LEVEL OF EVIDENCE

Level 1.

Blood-flow restricted exercise following ankle fractures - A feasibility study

BACKGROUND

The objective was to investigate the feasibility of blood flow restricted exercise (BFRE) as a rehabilitation modality in patients with a unilateral ankle fracture.

METHODS

Feasibility study with a prospective cohort design. Inclusion criteria were above 18 years of age and unilateral ankle fractures.

EXCLUSION CRITERIA

history of cardiac or embolic diseases, cancer, diabetes, hypertension and family history of cardio or vascular diseases. The predefined feasibility outcome was based on three criteria regarding patients experience with participating in the BFRE protocol and the absence of any serious adverse events.

RESULTS

Eight patients were included. Median age was 33 years (range: 23-60). All eight patients reported maximum satisfaction on the two questions regarding patient's perception of the overall experience with BFRE training and the feasibility to introduce BFRE as an intervention.

CONCLUSION

Early use of BFRE in patients with unilateral ankle fractures seems feasible in patients without comorbidity.

Does Blood Flow Restriction Therapy Improve Leg Strength in Patients With a Painful Total Knee Arthroplasty?

BACKGROUND

Blood flow restriction (BFR) therapy has been proposed to help patients build strength with fewer repetitions than standard physical therapy (PT). We sought to determine if BFR would improve quadriceps and hamstring strength in patients with instability and perceived weakness >1 year after primary total knee arthroplasty (TKA).

METHODS

We retrospectively reviewed 48 patients with painful TKAs and flexion instability as well as quadriceps and hamstring weakness who performed a 6-week PT program and received isokinetic strength measurements (ISMs). Thirty-six patients completed a standard PT program (non-BFR) and 12 patients completed a BFR regimen. ISMs were taken before and after PT to quantify quadriceps and hamstring power, torque, and work compared to the contralateral leg. Statistical analysis was conducted on pre-PT and post-PT ISMs and decisions for revision surgery.

RESULTS

There were no differences in ISMs after PT between the BFR and non-BFR groups. The non-BFR group showed statistically significant strength improvements in flexion but not extension (+28.7%-32.8%, P = .0145-.255). Although no significant difference was found in the BFR group, they saw improvements in all extension strength metrics (19.4%-23.4%, P = .3315-.3901) and flexion (25.7%-29.9%, P = .1994-.2392). No difference was observed between the groups in the rates of subsequent revision TKA (8.3% vs 16.7%, P = .3362).

CONCLUSION

BFR did not improve quadriceps and hamstring strength compared to PT alone in patients with instability and weakness after TKA. Over 80% of total patients chose to avoid revision TKA after completion of focused PT with or without BFR.

An Overview of Blood Flow Restriction Physiology and Clinical Considerations

ABSTRACT

The utilization of blood flow restriction has garnished considerable attention due to its widespread application and benefits that include strength enhancement, muscle hypertrophy, and increased level of function for specific populations. Blood flow restriction induces a hypoxic environment within a muscle group, initiating a metabolic cascade that stimulates muscle protein synthesis, altered gene regulation of muscle satellite cells, and increased muscle fiber recruitment, ultimately resulting in improved strength and endurance. When using blood flow restriction, consideration of the individual patient, occlusion pressure, cuff width, and cuff size are paramount. Blood flow restriction has been proven to be a consistently safe and effective tool for augmenting rehabilitative regimens for the upper and lower extremity.

Comparing hip and knee focused exercises versus hip and knee focused exercises with the use of blood flow restriction training in adults with patellofemoral pain

BACKGROUND

Hip and knee strengthening exercises are implemented in rehabilitation of patellofemoral pain patients, but typically use high loads (70% of 1 repetition maximum). This may lead to increased patellofemoral joint stress. Low load training (20-30% of 1 repetition maximum) with blood flow restriction could allow for exercise strength benefits to proximal and distal muscles with reduced joint stress and by promoting hypoalgesia.

AIM

The aim of this study was to compare hip and knee focused exercises with and without blood flow restriction in adults with patellofemoral pain for short term effectiveness.

DESIGN

A randomized observed-blind controlled trial.

SETTING

Musculoskeletal laboratories of the European University Cyprus, Nicosia, Cyprus.

POPULATION

60 volunteer patients, 18-40 years of age with patellofemoral pain.

METHODS

Participants were randomly assigned to (1 reference group) hip and knee strengthening at (70% of 1 repetition maximum) or (2 experimental group) Strengthening with blood flow restriction at (30% of 1 repetition maximum at 70% of limb occlution pressure). Treatments took place 3 times per week for 4weeks and outcomes were assessed at baseline, end of treatment and at 2-month follow-up. The primary outcome was the Kujala Anterior Knee Pain Scale and secondary outcomes were worst and usual pain, pain with Single leg Squats, the maximum pain free flexion angle, the Tampa Scale of kinesiophobia, the Pain Catastrophizing Scale and isometric strength of knee extensors, hip extensors and hip abductors.

RESULTS

No difference were found for the main outcome of this study between groups. There was a significant effect of time for all outcome measures in both groups. Between group differences showed a significant difference for isometric strength of Knee extensor values at 2 month follow-up F(1,58)=5.56, P=0.02, partial η2=0.09, 459.4 (412.13, 506.64) vs. 380.68 (333.42, 427.93) and in worst pain post-treatment F(1,58)=5.27, P=0.02, partial η²=0.08, 0.76 (0.48, 1.04) vs. reference group 1.30 (0.91, 1.68) with significantly better scores in the blood flow restriction group.

CONCLUSIONS

Blood flow restriction exercises of the hip and knee musculature used in this study were as effective as usual exercises of Hip and knee musculature in reducing symptoms in the short term. They also indicated greater increases in strength and reduction of worst pain post-treatment.

CLINICAL REHABILITATION IMPACT

Further research is needed to investigate the dose response relationship with longer follow-ups.

Overall Safety and Risks Associated with Blood Flow Restriction Therapy: A Literature Review

INTRODUCTION

Blood flow restriction therapy (BFRT) is used in scenarios ranging from muscle building in athletic performance to decreasing recovery time in postoperative orthopedic rehabilitation. The efficacy of BFRT for treating diseases has been increasingly researched; however, there has been less literature focused on establishing the safety of this therapy.

MATERIALS AND METHODS

An extensive literature review pertaining to BFRT and any deleterious events related to its usage was completed by searching multiple databases, including PubMed, EMBASE, and Cochrane Library using the terms "blood flow restriction therapy" or "KAATSU."

RESULTS

Ten case reports, five case series, two national surveys, two questionnaires, six randomized controlled studies, and one systematic review were included. A total of 1,672 individuals reported an adverse event following BFRT use out of 25,813 individuals. Commonly reported adverse events were numbness, dizziness, subcutaneous hemorrhage, and rhabdomyolysis. There were unique adverse effects of this therapy reported in individuals with comorbid conditions, such as hypertension and thoracic outlet syndrome, which included isolated cases of central retinal vein occlusion and Paget-Schroeder syndrome.

CONCLUSION

Blood flow restriction provides tremendous opportunity with a potential for accelerated exercise rehabilitation and injury prevention. This modality could be used in the military setting to help injured active duty personnel expeditiously return to deployable status. Further prospective randomized controlled trials are warranted to further support BFRT safety; however, from this literature review, it can be concluded that BFRT can be utilized safely in the proper patient population when administered by qualified professionals who have undergone the appropriate training.

A Useful Blood Flow Restriction Training Risk Stratification for Exercise and Rehabilitation

Blood flow restriction training (BFRT) is a modality with growing interest in the last decade and has been recognized as a critical tool in rehabilitation medicine, athletic and clinical populations. Besides its potential for positive benefits, BFRT has the capability to induce adverse responses. BFRT may evoke increased blood pressure, abnormal cardiovascular responses and impact vascular health. Furthermore, some important concerns with the use of BFRT exists for individuals with established cardiovascular disease (e.g., hypertension, diabetes mellitus, and chronic kidney disease patients). In addition, considering the potential risks of thrombosis promoted by BFRT in medically compromised populations, BFRT use warrants caution for patients that already display impaired blood coagulability, loss of antithrombotic mechanisms in the vessel wall, and stasis caused by immobility (e.g., COVID-19 patients, diabetes mellitus, hypertension, chronic kidney disease, cardiovascular disease, orthopedic post-surgery, anabolic steroid and ergogenic substance users, rheumatoid arthritis, and pregnant/postpartum women). To avoid untoward outcomes and ensure that BFRT is properly used, efficacy endpoints such as a questionnaire for risk stratification involving a review of the patient's medical history, signs, and symptoms indicative of underlying pathology is strongly advised. Here we present a model for BFRT pre-participation screening to theoretically reduce risk by excluding people with comorbidities or medically complex histories that could unnecessarily heighten intra- and/or post-exercise occurrence of adverse events. We propose this risk stratification tool as a framework to allow clinicians to use their knowledge, skills and expertise to assess and manage any risks related to the delivery of an appropriate BFRT exercise program. The questionnaires for risk stratification are adapted to guide clinicians for the referral, assessment, and suggestion of other modalities/approaches if/when necessary. Finally, the risk stratification might serve as a guideline for clinical protocols and future randomized controlled trial studies.

Postoperative Use of Blood Flow Restriction in Orthopedics

Blood flow restriction (BFR) therapy is being used more frequently for rehabilitation from orthopedic injuries. Several physiologic mechanisms of action, at local and systemic levels, have been proposed. Numerous studies have investigated the effects of BFR training in healthy athletes; however, limited clinical data exist supporting the use of BFR after surgery. Given that BFR training may facilitate muscle development using low-load resistance exercises, it offers a unique advantage for the post-surgical patient who cannot tolerate traditional high resistance training. [Orthopedics. 2021;44(6):e694-e698.].

Time to Save Time: Beneficial Effects of Blood Flow Restriction Training and the Need to Quantify the Time Potentially Saved by Its Application During Musculoskeletal Rehabilitation

The main goal of musculoskeletal rehabilitation is to achieve the pre-injury and/or pre-surgery physical function level with a low risk of re-injury. Blood flow restriction (BFR) training is a promising alternative to conventional therapy approaches during musculoskeletal rehabilitation because various studies support its beneficial effects on muscle mass, strength, aerobic capacity, and pain perception. In this perspective article, we used an evidence-based progressive model of a rehabilitative program that integrated BFR in 4 rehabilitation phases: (1) passive BFR, (2) BFR combined with aerobic training, (3) BFR combined with low-load resistance training, and (4) BFR combined with low-load resistance training and traditional high-load resistance training. Considering the current research, we propose that a BFR-assisted rehabilitation has the potential to shorten the time course of therapy to reach the stage where the patient is able to tolerate resistance training with high loads. The information and arguments presented are intended to stimulate future research, which compares the time to achieve rehabilitative milestones and their physiological bases in each stage of the musculoskeletal rehabilitation process. This requires the quantification of BFR training-induced adaptations (eg, muscle mass, strength, capillary-to-muscle-area ratio, hypoalgesia, molecular changes) and the associated changes in performance with a high measurement frequency (≤1 week) to test our hypothesis. This information will help to quantify the time saved by BFR-assisted musculoskeletal rehabilitation. This is of particular importance for patients, because the potentially accelerated recovery of physical functioning would allow them to return to their work and/or social life earlier. Furthermore, other stakeholders in the health care system (eg, physicians, nurses, physical therapists, insurance companies) might benefit from that with regard to work and financial burden.

Responses of platelet CD markers and indices to resistance exercise with and without blood flow restriction in patients with type 2 diabetes

BACKGROUND

Diabetes mellitus is a common disorder with the risk of vascular injury.

OBJECTIVE

The aim of this study was to compare the effects of low-intensity resistance exercise with blood flow restriction versus high-intensity resistance exercise on platelet CD markers and indices in patients with type 2 diabetes.

METHODS

Fifteen female patients with type 2 diabetes (Mean±SD; age, 47.6±7.2 yrs) randomly completed two resistance exercise at an intensity corresponding to 20% and 80% of one-repetition maximum (1-RM), with and without blood flow restriction (REBFR and RE), respectively. We measured markers of platelet activation (P-selectin, GpIIb/IIIa, and CD42) and platelet indices before and immediately after exercise, and after 30 min recovery.

RESULTS

Platelet count (PLT) and plateletcrit (PCT) increased in response to REBFR more than the RE (p <  0.05), though, no significant differences in PDW and MPV were observed (p <  0.05). Although P-selectin (CD62P), CD61, CD41, and CD42 were reduced following resistance exercise in both trials, these reductions were non-significant (p <  0.05). Besides, no significant between-group differences were found for platelet CD markers (p <  0.05).

CONCLUSIONS

It is concluded that REBFR induces thrombocytosis, but responses of platelet CD markers in patients with type 2 diabetes are similar following low-intensity REBFR and high-intensity RE.

Perceived Barriers to Blood Flow Restriction Training

Blood flow restriction (BFR) training is increasing in popularity in the fitness and rehabilitation settings due to its role in optimizing muscle mass and strength as well as cardiovascular capacity, function, and a host of other benefits. However, despite the interest in this area of research, there are likely some perceived barriers that practitioners must overcome to effectively implement this modality into practice. These barriers include determining BFR training pressures, access to appropriate BFR training technologies for relevant demographics based on the current evidence, a comprehensive and systematic approach to medical screening for safe practice and strategies to mitigate excessive perceptual demands of BFR training to foster long-term compliance. This manuscript attempts to discuss each of these barriers and provides evidence-based strategies and direction to guide clinical practice and future research.

Blood Flow Restriction Training: To Adjust or Not Adjust the Cuff Pressure Over an Intervention Period?

Blood flow restriction (BFR) training combines exercise and partial reduction of muscular blood flow using a pressured cuff. BFR training has been used to increase strength and muscle mass in healthy and clinical populations. A major methodological concern of BFR training is blood flow restriction pressure (BFRP) delivered during an exercise bout. Although some studies increase BFRP throughout a training intervention, it is unclear whether BFRP adjustments are pivotal to maintain an adequate BFR during a training period. While neuromuscular adaptations induced by BFR are widely studied, cardiovascular changes throughout training intervention with BFR and their possible relationship with BFRP are less understood. This study aimed to discuss the need for BFRP adjustment based on cardiovascular outcomes and provide directions for future researches. We conducted a literature review and analyzed 29 studies investigating cardiovascular adaptations following BFR training. Participants in the studies were healthy, middle-aged adults, older adults and clinical patients. Cuff pressure, when adjusted, was increased during the training period. However, cardiovascular outcomes did not provide a plausible rationale for cuff pressure increase. In contrast, avoiding increments in cuff pressure may minimize discomfort, pain and risks associated with BFR interventions, particularly in clinical populations. Given that cardiovascular adaptations induced by BFR training are conflicting, it is challenging to indicate whether increases or decreases in BFRP are needed. Based on the available evidence, we suggest that future studies investigate if maintaining or decreasing cuff pressure makes BFR training safer and/or more comfortable with similar physiological adaptation.

Application and side effects of blood flow restriction technique: A cross-sectional questionnaire survey of professionals

The physiological benefits of applying blood flow restriction (BFR) in isolation or in the presence of physical exercise have been widely documented in the scientific literature. Most investigations carried out under controlled laboratory conditions have found the technique to be safe. However, few studies have analyzed the use of the technique in clinical settings.To analyze how the BFR technique has been applied by professionals working in the clinical area and the prevalence of side effects (SEs) resulting from the use of this technique.This is a cross-sectional study. A total of 136 Brazilian professionals who perform some function related to physical rehabilitation, sports science, or physical conditioning participated in this study. Participants answered a self-administered online questionnaire consisting of 21 questions related to the professional profile and methodological aspects and SEs of the BFR technique.Professionals reported applying the BFR technique on individuals from different age groups from youth (≤18 years; 3.5%) to older adults (60-80 years; 30.7%), but mainly on people within the age group of 20 to 29 years (74.6%). A total of 99.1% of the professionals coupled the BFR technique with resistance exercise. Their main goals were muscle hypertrophy and physical rehabilitation. The majority (60.9%) of interviewees reported using BFR in durations of less than 5 minutes and the pressure used was mainly determined through the values of brachial blood pressure and arterial occlusion. Moreover, 92% of professionals declared observing at least 1 SE resulting from the BFR technique. Most professionals observed tingling (71.2%) and delayed onset of muscle soreness (55.8%). Rhabdomyolysis, fainting, and subcutaneous hemorrhaging were reported less frequently (1.9%, 3.8%, and 4.8%, respectively).Our findings indicate that the prescription of blood flow restriction technique results in minimal serious side effects when it is done in a proper clinical environment and follows the proposed recommendations found in relevant scientific literature.

The effectiveness of blood-flow restricted resistance training in the musculoskeletal rehabilitation of patients with lower limb disorders: A systematic review and meta-analysis

OBJECTIVE

This meta-analysis aimed to evaluate the effectiveness of low-load Resistance Training (RT) with or without Blood Flow Restriction (BFR) compared with conventional RT on muscle strength in open and closed kinetic chains, muscle volume and pain in individuals with orthopaedic impairments.

DATA SOURCES

Searches were conducted in the PubMed, Web of Science, Scopus and Cochrane databases, including the reference lists of randomised controlled trials (RCT's) up to January 2021. Review method: An independent reviewer extracted study characteristics, orthopaedic indications, exercise data and outcome measures. The primary outcome was muscle strength of the lower limb. Secondary outcomes were muscle volume and pain. Study quality and reporting was assessed using the TESTEX scale.

RESULTS

A total of 10 RCTs with 386 subjects (39.2 ± 17.1 years) were included in the analysis to compare low-load RT with BFR and high or low-load RT without BFR. The meta-analysis showed no significant superior effects of low-load resistance training with BFR regarding leg muscle strength in open and closed kinetic chains, muscle volume or pain compared with high or low-load RT without BFR in subjects with lower limb impairments.

CONCLUSION

Low-load RT with BFR leads to changes in muscle strength, muscle volume and pain in musculoskeletal rehabilitation that are comparable to conventional RT. This appears to be independent of strength testing in open or closed kinetic chains.

The Safety of Blood Flow Restriction Training as a Therapeutic Intervention for Patients With Musculoskeletal Disorders: A Systematic Review

BACKGROUND

The effectiveness of blood flow restriction training (BFRT) as compared with other forms of training, such as resistance training, has been evaluated in the literature in clinical and nonclinical populations. However, the safety of this intervention has been summarized only in healthy populations and not in clinical populations with musculoskeletal disorders.

PURPOSE

To evaluate the safety and adverse events associated with BFRT in patients with musculoskeletal disorders.

STUDY DESIGN

Systematic review.

METHODS

A literature search was conducted with 3 online databases (MEDLINE, CINAHL, and Embase). Eligibility criteria for selecting studies were as follows: (1) BFRT was used as a clinical intervention, (2) study participants had a disorder of the musculoskeletal system, (3) authors addressed adverse events, (4) studies were published in English, and (5) the intervention was performed with human participants.

RESULTS

Nineteen studies met eligibility criteria, with a pooled sample size of 322. Diagnoses included various knee-related disorders, inclusion body myositis, polymyositis or dermatomyositis, thoracic outlet syndrome, Achilles tendon rupture, and bony fractures. Nine studies reported no adverse events, while 3 reported rare adverse events, including an upper extremity deep vein thrombosis and rhabdomyolysis. Three case studies reported common adverse events, including acute muscle pain and acute muscle fatigue. In the randomized controlled trials, individuals exposed to BFRT were not more likely to have an adverse event than individuals exposed to exercise alone. Of the 19 studies, the adverse events were as follows: overall, 14 of 322; rare overall, 3 of 322; rare BFRT, 3 of 168; rare control, 0 of 154; any adverse BFRT, 10 of 168; any adverse control, 4 of 154. A majority of studies were excluded because they did not address safety.

CONCLUSION

BFRT appears to be a safe strengthening approach for knee-related musculoskeletal disorders, but further research is needed to make definitive conclusions and to evaluate the safety in other musculoskeletal conditions. Improved definitions of adverse events related to BFRT are needed to include clear criteria for differentiating among common, uncommon, and rare adverse events. Finally, further research is needed to effectively screen who might be at risk for rare adverse events.

Perioperative Blood Flow Restriction Rehabilitation in Patients Undergoing ACL Reconstruction: A Systematic Review

Background:

Low-load blood flow restriction (BFR) training has attracted attention as a potentially effective method of perioperative clinical rehabilitation for patients undergoing orthopaedic procedures.

Purpose:

To (1) compare the effectiveness of low-load BFR training in conjunction with a standard rehabilitation protocol, pre- and postoperatively, and non-BFR interventions in patients undergoing anterior cruciate ligament reconstruction (ACLR) and (2) evaluate protocols for implementing BFR perioperatively for patients undergoing ACLR.

Study Design:

Systematic review; Level of evidence, 2.

Methods:

A systematic review of the 3 medical literature databases was conducted to identify all level 1 and 2 clinical trials published since 1990 on BFR in patients undergoing ACLR. Patient demographics from included studies were pooled. Outcome data were documented, including muscle strength and size, and perceived pain and exertion. A descriptive analysis of outcomes from BFR and non-BFR interventions was performed.

Results:

A total of 6 studies (154 patients; 66.2% male; mean ± SD age, 24.2 ± 3.68 years) were included. Of these, 2 studies examined low-load BFR as a preoperative intervention, 1 of which observed a significant increase in muscle isometric endurance (P = .014), surface electromyography of the vastus medialis (P < .001), and muscle blood flow to the vastus lateralis at final follow-up (P < .001) as compared with patients undergoing sham BFR. Four studies investigated low-load BFR as a postoperative intervention, and they observed significant benefits in muscle hypertrophy, as measured by cross-sectional area; strength, as measured by extensor torque; and subjective outcomes, as measured by subjective knee pain during session, over traditional low-load resistance training (all P < .05). BFR occlusion periods ranged from 3 to 5 minutes, with rest periods ranging from 45 seconds to 3 minutes.

Conclusion:

This systematic review found evidence on the topic of BFR rehabilitation after ACLR to be sparse and heterogeneous likely because of the relatively recent onset of its popularity. While a few authors have demonstrated the potential strength and hypertrophy benefits of perioperative BFR, future investigations with standardized outcomes, long-term follow-up, and more robust sample sizes are required to draw more definitive conclusions.