Use Of Blood Flow Restriction Research Articles

Blood Flow Restriction Training Improves Muscular Outcomes in Patients With Chronic Ankle Instability: A Critically Appraised Topic

Clinical Scenario: The high recurrence of lateral ankle sprains progresses to chronic ankle instability (CAI) and can affect many athletes in all sports. CAI is often associated with a decrease in muscle strength, an increase in pain, a decrease in the range of motion, and a decrease in balance or neuromuscular control. The use of blood flow restriction (BFR) with CAI can increase muscular outcomes and be used as a rehabilitation tool. Clinical Question: Is there evidence to suggest that BFR improves strength, muscle activation, and/or cross-sectional area of the lower leg musculature in those with CAI? Clinical Bottom Line: There is moderate evidence to support therapeutic exercise with low-intensity BFR in patients with CAI. The evidence concluded a significant improvement in BFR to increase muscle activation of the fibularis longus, anterior tibialis, vastus lateralis, and soleus. There is moderate evidence suggesting BFR can induce strength gains in the muscles of the lower extremity in patients with CAI. Strength of Recommendation: The comprehensive evidence is a Strength of Recommendation Taxonomy (SORT) Grade B, with a level of evidence of 2, according to the Centre for Evidence-Based Medicine (CEBM) for the studies included.

Blood Flow Restriction Enhances Recovery After Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-analysis of Randomized Controlled Trials

To conduct a systematic review and meta-analysis of randomized controlled trials (RCTs) evaluating neuromuscular and clinical outcomes of blood flow restriction (BFR) training after anterior cruciate ligament reconstruction (ACLR) compared with non-BFR rehabilitation protocols. A systematic review was performed in accordance with the 2020 Preferred Reporting Items for Systematic reviews and Meta Analyses guidelines by querying PubMed, MEDLINE, Scopus, the Cochrane Database for Systematic Review, and the Cochrane Central Register for Controlled Trials databases from inception through December 2023 to identify Level I and II RCTs evaluating outcomes of BFR training after ACLR compared with non-BFR rehabilitation. A meta-analysis was performed using random-effects models with standardized mean difference (SMD) for pain, muscle strength, and muscle volume, whereas mean difference was calculated for patient-reported outcome measures. Eight RCTs, consisting of 245 patients, met inclusion criteria, with 115 patients undergoing non-BFR rehabilitation compared with 130 patients undergoing BFR after ACLR. Mean patient age was 27.2 ± 6.7 years, with most patients being male (63.3%, n= 138/218). The length of the BFR rehabilitation protocol was most commonly between 8 and 12 weeks (range, 14 days to 16 weeks). Most studies set the limb/arterial occlusion pressure in the BFR group at 80%. When compared with non-BFR rehabilitation, BFR resulted in significant improvement in isokinetic muscle strength (SMD: 0.77, P= .02, I2: 58%), International Knee Documentation Committee score (mean difference: 10.97, P ≤ .00001, I2: 77%), and pain (SMD: 1.52, P= .04, I2: 87%), but not quadriceps muscle volume (SMD: 0.28, P= .43, I2: 76%). The use of BFR after ACLR led to improvements in pain, International Knee Documentation Committee score, and isokinetic muscle strength, with variable outcomes on the basis of quadriceps strength, volume, and thickness when compared with non-BFR rehabilitation. Level II, systematic review and meta-analysis of Level I and II studies.

Blood Flow Restriction Therapy After Anterior Cruciate Ligament Reconstruction

Anterior cruciate ligament reconstruction (ACLR) rehabilitation necessitates restoration of quadriceps strength to minimize reinjury and optimize return to sport (RTS). Patients recovering from ACLR are limited by pain and activity restrictions, resulting in quadriceps muscle atrophy. Blood flow restriction (BFR) therapy involves performing exercises while a specialized blood pressure cuff is applied to the proximal aspect of the operative extremity and inflated to 40% to 90% of the arterial occlusion pressure, as determined using Doppler ultrasonography. BFR is theorized to induce an anaerobic environment and metabolic stress during exercise, promoting muscle hypertrophy and strength gains. Although the physiological mechanism has not been fully elucidated, it is theorized that BFR combined with low-load resistance training could yield muscle adaptations comparable to those of high-load resistance training. For ACLR patients with pain and restrictions precluding high-intensity strength training, incorporation of BFR into postoperative rehabilitation protocols could help mitigate quadriceps weakness and promote RTS. Randomized controlled trials report a prolonged, dose-dependent relation between BFR use and quadriceps and hamstring strength gains, improved bone and muscle mass, and earlier RTS, whereas other studies report no significant difference in quadriceps size, strength, or patient satisfaction compared with controls. Furthermore, although generally considered safe, there are rare reports of associated adverse events such as rhabdomyolysis, and BFR should be avoided in patients with a history of thromboembolic disease or peripheral vasculopathy. The literature examining BFR after ACLR is heterogeneous; lacks standardization; and contains broad variation in reported cuff pressures, as well as timing and duration of BFR use, among protocols. Although the use of BFR after ACLR shows promise, further study is necessary to elucidate the efficacy, safety, and optimal protocols.

Novel Blood Flow Restriction Therapy Protocol for the Treatment of Postamputation Weakness and Pain due to Osteosarcoma: A Case Study

BACKGROUND: Pain and weakness are 2 commonly reported postamputation symptoms. The purpose of this case report is to propose a novel blood flow restriction (BFR) protocol to address pain and weakness in a patient with transtibial limb loss. CASE PRESENTATION: A 36-year-old male 2 months after transtibial amputation presented for evaluation and treatment of his postamputation pain, weakness, and poor functional mobility. The patient completed a novel BFR strength protocol twice per week for 12 weeks. OUTCOME AND FOLLOW-UP: Amputee Mobility Predictor, L Test Measure of Functional Mobility, 2-minute walk test, 30-second sit to stand, hamstring force, single-limb leg press repetition maximum, hip abduction endurance test, and numeric pain scale preintervention and postintervention were measured. The patient achieved the minimal detectable change for the L-Test and 2MWT, resulting in meaningful improvement in the patient’s strength and function following the blood flow restriction protocol. DISCUSSION: This case supports the use of blood flow restriction to address postamputation weakness and pain in a physical therapy setting. JOSPT Cases 2024;4(1):1-7. Epub 30 November 2023. doi:10.2519/josptcases.2023.11327

Current Implementation and Barriers to Using Blood Flow Restriction Training: Insights From a Survey of Allied Health Practitioners.

Scott, BR, Marston, KJ, Owens, J, Rolnick, N, and Patterson, SD. Current implementation and barriers to using blood flow restriction training: Insights from a survey of allied health practitioners. J Strength Cond Res 38(3): 481-490, 2024-This study investigated the use of blood flow restriction (BFR) exercise by practitioners working specifically with clinical or older populations, and the barriers preventing some practitioners from prescribing BFR. An online survey was disseminated globally to allied health practitioners, with data from 397 responders included in analyses. Responders who had prescribed BFR exercise ( n = 308) completed questions about how they implement this technique. Those who had not prescribed BFR exercise ( n = 89) provided information on barriers to using this technique, and a subset of these responders ( n = 22) completed a follow-up survey to investigate how these barriers could be alleviated. Most practitioners prescribe BFR exercise for musculoskeletal rehabilitation clients (91.6%), with the BFR cuff pressure typically relative to arterial occlusion pressure (81.1%) and implemented with resistance (96.8%) or aerobic exercise (42.9%). Most practitioners screen for contraindications (68.2%), although minor side effects, including muscle soreness (65.8%), are common. The main barriers preventing some practitioners from using BFR are lack of equipment (60.2%), insufficient education (55.7%), and safety concerns (31.8%). Suggestions to alleviate these barriers included developing educational resources about the safe application and benefits of BFR exercise ( n = 20) that are affordable ( n = 3) and convenient ( n = 4). These results indicate that BFR prescription for clinical and older cohorts mainly conforms with current guidelines, which is important considering the potentially increased risk for adverse events in these cohorts. However, barriers still prevent broader utility of BFR training, although some may be alleviated through well-developed educational offerings to train practitioners in using BFR exercise.

Exercise-induced hypoalgesia with end-stage knee osteoarthritis during different blood flow restriction levels: sham-controlled crossover study.

blood flow restriction (BFR) training could be a valuable treatment to induce exercise-induced hypoalgesia (EIH) in patients with end-stage knee osteoarthritis. However, the use of BFR in these patients is poorly explored and there is no evidence about the training dosage needed. To evaluate the effect of resistance training protocols with different occlusion levels of blood flow restriction (BFR) on EIH in patients with end-stage knee osteoarthritis. Crossover study. University physical exercise laboratory. 26 adults with end-stage knee osteoarthritis. Patients performed 4 sets (30, 15, 15 and 15 repetitions) separated by 1-minute rests of three protocols/sessions of low-load (30% 1RM) seated knee extensions with elastic bands and BFR: placebo (sham BFR), BFR at 40% arterial occlusion pressure (AOP) and BFR at 80% AOP. Pressure Pain Thresholds (PPT) and Visual Analog Scale (VAS) collected before, immediate post session and post 10 minutes. No differences in EIH between the different levels of BFR were found. However, 80% AOP protocol worsened VAS scores immediately (Mean difference, MD (95%CI): -21.190 (-33.897 to -8.484)) while improving PPT immediately (MD (95%CI); affected limb: -.629 (-1.080 to -.177); contralateral: -.590 (-.986 to -.195)) and at 10 min (MD (95%CI); affected limb: -.633 (-1.153 to -.113); contralateral: -.676 (-1.136 to -.216); and forearm: -.467 (-.881 to -.053)) post-exercise compared to baseline. There is no EIH difference after using different occlusion levels. EIH is modulated by pain-related psychological constructs and self-perceived health status.

Use of a handheld Doppler to measure brachial and femoral artery occlusion pressure.

Objective: Measurement of arterial occlusion pressure (AOP) is essential to the safe and effective use of blood flow restriction during exercise. Use of a Doppler ultrasound (US) is the "gold standard" method to measure AOP. Validation of a handheld Doppler (HHDOP) device to measure AOP could make the measurement of AOP more accessible to practitioners in the field. The purpose of this study was to determine the accuracy of AOP measurements of the brachial and femoral arteries using an HHDOP. Methods: We simultaneously measured AOP using a "gold standard" US and a HHDOP in the dominant and non-dominant arms (15 males; 15 females) and legs (15 males; 15 females). Results: There were no differences in limb circumference or limb volume in the dominant and non-dominant arms and legs between males and females or between the dominant and non-dominant arms and legs of males and females. The differences between US and HHDOP measures of AOP in the dominant and non-dominant arms and legs were either not significant or small (<10mmHg) and of little practical importance. There were no sex differences in AOP measurements of the femoral artery (p > 0.60). Bland-Altman analysis yielded an average bias (-0.65mmHg; -2.93mmHg) and reasonable limits of agreement (±5.56mmHg; ±5.58mmHg) between US and HHDOP measures of brachial and femoral artery AOP, respectively. Conclusion: HHDOP yielded acceptable measures of AOP of the brachial and femoral arteries and can be used to measure AOP by practitioners for the safe and effective use of blood flow restriction. Due to the potential differences in AOP between dominant and non-dominant limbs, AOP should be measured in each limb.

Potential Local Mechanisms for Exercise-Induced Hypoalgesia in Response to Blood Flow Restriction Training.

Overall, there is a great need within sports medicine to ensure that athletes can return from injury in an efficient, yet thorough manner. It is crucial to not avoid necessary difficulties in this process but also to ensure time-efficient rehabilitation. One of the more promising techniques to achieve timely recovery is blood flow restriction (BFR) training. BFR training is a growing and novel development that could be a vital tool to lighten the burden of recovery from injury in athletes. BFR utilizes a pneumatic tourniquet to limit blood flow in specific areas of the body. The use of BFR has been shown to potentially enhance the analgesic effects of exercise-induced hypoalgesia (EIH). By limiting pain, athletes will be less burdened by mobility and loading exercises required for them to effectively return to play. In a field where time away from sports can have massive implications, the need for tools to assist in the acceleration of the rehabilitation process is vital. Much of the work that has already been done in the field has been able to exploit the benefits of EIHand further enhance the body's capabilities through BFR. Studies have compared EIH at low- and high-intensity settings utilizing BFR with both resistance and aerobic exercise. The results of these studies show comparable beta-endorphin levels with high-intensity exercise without BFR and low-intensity exercise with BFR. Low-intensity training with BFR had greater local pain relief, perhaps indicating the promising effects of BFR in enhancing EIH. By reviewing the current literature on this topic, we hope that further progress can be made to better understand the mechanism behind BFR and its ability to enhance EIH. Currently, local metabolites are a major focus for the potential mechanism behind these effects. Mas-related G-protein-coupled receptors (Mrgprs) contribute to local pain pathways via mast cell degranulation. Similarly, chemokine receptor 2/chemokine ligand 2 (CCR2/CCL2) triggers mast cell degranulation and inflammation-induced pain. Finally, pain-reducing effects have been linked to anti-inflammatory IL-10 signaling and anaerobic metabolites via transient receptor potential vanilloid 1 (TRPV1). Through a better understanding of these metabolites and their mechanisms, it is possible to further exploit the use of BFR to not only serve athletes recovering from injury but also apply this information to better serve all patients.

Poster 322: Blood Flow Restriction after ACL Reconstruction Does Not Accelerate Quadriceps Strengthening

Objectives: The use of blood flow restriction (BFR) therapy has gained popularity as an adjunct rehabilitation technique following anterior cruciate ligament reconstruction (ACLR). The purpose of this study was to longitudinally evaluate the impact that BFR has on quadriceps strength following ACLR with quadriceps tendon (QT) autograft in comparison to traditional rehabilitation protocols. Methods: Patients undergoing primary ACLR with QT autograft at a single institution were retrospectively reviewed. Included patients had a minimum of two isometric strength testing sessions via electromechanical dynamometer (Biodex). Obtained strength measures included peak knee extension torque of the operative extremity and knee extension ratio (KER), in which the ratio of peak knee extension torque of the operative extremity and nonoperative extremity were compared. Strength measures were compared between patients that received BFR during postoperative rehabilitation and patients that underwent traditional rehabilitation without BFR for up to three strength measurement sessions. Demographic and surgical factors including patient age at surgery, sex, BMI, level of competition, time from injury to surgery, time from surgery to strength measurement session, use of regional anesthesia, tourniquet time, and concomitant surgery were collected. Two group comparisons of continuous and categorical variables were analyzed by using Mann-Whitney U and chi-squared test, respectively. Statistical significance was set at 0.05. Results: A total of 45 patients (26 female) in the BFR group and 36 patients (13 female) in the traditional rehabilitation group met inclusion criteria. Mean age of the entire cohort was 19.5 years. There were no statistically significant differences among demographic or surgical factors between BFR and traditional cohorts. Of patients receiving BFR therapy, the mean number of BFR treatments was 18 from surgery to first strength measurement, 8 between first and second strength measurements, and 9 between the second and third strength measurements. Peak knee extension torque was lower for the BFR (96 Nm) group than traditional (111 Nm) group at the first strength measurement session (p=0.03) but was similar between groups at the second (118 Nm vs 134 Nm, p=0.1) and third (138 Nm vs 130 Nm, p =0.39) strength measurement sessions. There was no difference among BFR and traditional groups in the change of knee extension peak torque or change in KER between testing sessions. KER was lower at the second strength measurement in the BFR group (0.81) compared to the traditional group (0.90, p=0.02), though no differences existed at the first or third strength measurements. Conclusions: Sequential knee extension strength measurements following ACLR in a young patient cohort demonstrated improvements irrespective of BFR use. There were no differences in the change of strength measures between testing sessions when comparing BFR and traditional rehabilitation groups. Both groups demonstrated similar strength improvements over time, and BFR did not accelerate strength gains compared to traditional rehabilitation. However, as the BFR cohort had lower starting yet similar final strength measurements compared to the traditional rehabilitation cohort, a role for BFR over the long term in at risk patients cannot be excluded.

The effectiveness of blood flow restriction training in cardiovascular disease patients: A scoping review.

Therapeutic exercise is integral to the comprehensive rehabilitation of patients with cardiovascular disease and, as such, is recommended by the American Heart Association as a valuable and effective treatment method for such patients. The type of exercise applied to these patients is aerobic and resistance exercise with mild intensities and loads to avoid overloading the cardiovascular system. Blood flow restriction exercise is a novel exercise modality in clinical settings that has in many studies a similar effect on muscle hypertrophy, strength, and cardiovascular response to training at a 70% strength level without blood flow restriction. Since this exercise mode does not require high-intensity loads, it can be a safe method for improving muscle strength, cardiovascular endurance, and functionality in cardiovascular patients. Given that, the objective of this review is to assess and summarize existing evidence for the use of blood flow restriction in cardiovascular patients. A scoping review of existing clinical trials was conducted. Eleven studies were examined that suggested the use of blood flow restrictions in cardiovascular patients to achieve improvements in muscle strength, functionality, and cardiovascular parameters such as blood pressure decrease.

Effects of Blood Flow Restriction on Pain and Muscle Thickness Following Tendinopathy: A Case Study

Introduction: Blood flow restriction (BFR) training, in which an inflatable cuff partially occludes blood flow around the proximal portion of a limb, coupled with low-load resistance exercise (LLRE) has resulted in gains comparable with traditional progressive resistive exercise in healthy populations. The use of BFR with LLRE may help people with supraspinatus tendinopathy through proximal effects to improve strength and muscle size. The purpose of this case report is to describe the proximal effect of the LLRE+BFR program on a patient with supraspinatus tendinopathy.&#x0D; Materials and Methods: The patient was a 40-year-old man with a history of shoulder pain and weakness for the past months. He received an LLRE+BFR program for his right shoulder including rotator cuff and scapular strengthening exercises and lower limbs aerobic exercises based on protocols of strengthening and aerobic exercises of BFR. Outcomes measured at baseline and 4 weeks included the 4 items: 1) Strength of supraspinatus muscle and four scapular stabilizer muscles including serratus anterior strength, middle trapezius strength, and lower trapezius strength by dynamometer, 2) supraspinatus thickness by ultrasound, 3) pain pressure threshold of supraspinatus and deltoid muscles by algometer, and 4) pain reported bay in each session based on pain numeric scale.&#x0D; Results: After 6 weeks, the strength of supraspinatus and scapular stabilizers except for the lower trapezius increased. The supraspinatus thickness and pain pressure threshold in the supraspinatus and deltoid muscle also increased after 4 weeks. The mean of pain reported by the patient based on the pain numeric scale before and after each session was also decreased.&#x0D; Conclusion: The patient had measurable improvements following the use of an LLRE+BFR program. LLRE+BFR program may be an option for strength training in people with supraspinatus tendinopathy; however, more research is needed to determine effectiveness across the population of people with supraspinatus tendinopathy.&#x0D;

Survey of blood flow restriction therapy for rehabilitation in Sports Medicine patients

Blood flow restriction (BFR) therapy has demonstrated benefits across a spectrum of musculoskeletal injuries, including improved strength, endurance, function, and reduction in pain perception. There is, however, no standardized application of BFR therapy among orthopaedic surgeons within the United States (US). The indication and protocol for BFR therapy vary significantly across providers in the US. An online survey of 21 multiple-choice questions was sent to 3,281 surgeons listed on a large orthopaedic registry. A cross-sectional study was performed on all surgeons who successfully completed the questionnaire. Surgeons were queried on current or planned use of BFR, indications, contraindications, and peri-operative and non-operative management of sports-related injuries. Overall, 250 physicians completed the survey, with 149 (59.8%) reporting current BFR use and 75.2% initiating use in the last 1-5 years. Most protocols (78.8%) utilize the modality 2-3 times per week while 15.9% use it only once weekly. Anterior cruciate ligament reconstruction (ACLR) rehabilitation was the most reported indication for initiating BFR therapy (95.7%) along with medial patellofemoral ligament reconstruction (70.2%), multiligamentous knee reconstruction (68.8%), meniscus repair (62.4%), collateral ligament reconstruction (50.4%), Achilles tendon repairs (30.5%), and meniscectomy (27%). Only 36.5% reported using BFR after upper extremity procedures, such as distal biceps repair (19.7%), ulnar collateral ligament elbow reconstruction (17%), rotator cuff (16.8%), and shoulder labrum repair (15.3%). For non-operative injuries, 65.8% of surgeons utilized BFR. Of those not currently using BFR therapy, 33.3% intended to implement its use in the future. BFR therapy has increased in popularity with most physicians implementing its use in the last 5 years. BFR was commonly utilized after ACLR. BFR allows light-load resistance to simulate high-intensity resistance training. This study describes US orthopaedic surgeons' common practice patterns and patient populations that utilize BFR therapy.

The use of blood flow restriction does not enhance adaptations of corticospinal excitability or intracortical inhibition after acute resistance training

Resistance exercise with blood flow restriction (BFR) is considered a safe and powerful training tool. Low-load (LL) resistance training with BFR results in comparable hypertrophy compared to conventional heavy-load (HL) resistance training (Centner et al., 2019). Additionally, LL training with BFR (LL-BFR) induces comparable (Grønfeldt et al., 2020) or slightly lower (Centner et al., 2019) effects on muscle strength than HL training. It is generally accepted that increases in maximum strength are mediated by muscular hypertrophy and/or neural adaptations. However, the effect of BFR on neural adaptations is scarcely investigated. The aim of this study was therefore to investigate the effects of BFR on acute neural adaptations following a single bout of resistance training.&#x0D; Fifteen male participants (21-35 years) volunteered to participate in this study. On three separate days, participants performed a strength training session of the right elbow flexors with either LL, LL-BFR or HL. Neuromuscular adaptations were investigated before and after each resistance training session by means of transcranial magnetic stimulation (single- and paired-pulse TMS) and peripheral nerve stimulation (Mmax). Data were acquired during submaximal sustained isometric contractions. During LL-BFR, the cuff was inflated to 50% of the individual arterial occlusion pressure to restrict venous outflow in the working musculature during exercise.&#x0D; The preliminary data analysis with mixed linear models revealed that, compared to baseline values, normalized MEPs (% of Mmax) from the trained biceps brachii were enhanced for HL (Cohen’s d = 0.51) but not LL-BFR (Cohen’s d = 0.03) when compared to LL. None of the groups showed relevant changes in short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF). The size of Mmax decreased slightly for HL (Cohen’s d = -0.18) but not LL-BFR (Cohen’s d = 0.06) when compared to LL.&#x0D; This is the first study that investigated acute neural adaptations in response to resistance training with and without BFR. We observed increased MEP amplitudes after HL but not LL what is in line with previous evidence (Mason et al., 2019). Since training with BFR results in a rapid increase in motoneuronal excitability (Copithorne et al., 2020), the increased MEP are less likely caused by changes at the cortical site.&#x0D; Centner, C., Wiegel, P., Gollhofer, A., &amp; König, D. (2019). Effects of blood flow restriction training on muscular strength and hypertrophy in older individuals: A systematic review and meta-analysis. Sports Medicine, 49, 95-108. https://doi.org/10.1007/s40279-018-0994-1&#x0D; Copithorne, D. B., Rice, C. L., &amp; McNeil, C. J. (2020). Effect of blood flow occlusion on corticospinal excitability during sustained low-intensity isometric elbow flexion. Journal of Neurophysiology, 123(3), 1113-1119. https://doi.org/10.1152/jn.00644.2019&#x0D; Grønfeldt, B. M., Lindberg Nielsen, J., Mieritz, R. M., Lund, H., &amp; Aagaard, P. (2020). Effect of blood-flow restricted vs heavy-load strength training on muscle strength: Systematic review and meta-analysis. Scandinavian Journal of Medicine &amp; Science in Sports, 30(5), 837-848. https://doi.org/10.1111/sms.13632&#x0D; Mason, J., Howatson, G., Frazer, A. K., Pearce, A. J., Jaberzadeh, S., Avela, J., &amp; Kidgell, D. J. (2019). Modulation of intracortical inhibition and excitation in agonist and antagonist muscles following acute strength training. European Journal of Applied Physiology, 119, 2185-2199. https://doi.org/10.1007/s00421-019-04203-9

Blood Flow Restriction Following ACL Reconstruction

Background: Blood flow restriction (BFR) therapy is a technique that uses partial occlusion of arterial blood flow in tandem with low-load resistance training to promote an environment of metabolic stress within muscle tissue. It is hypothesized that such therapy can facilitate protein synthesis and muscle hypertrophy even in the setting of age, injury, or postoperative rehabilitation—conditions which are marred by muscle atrophy and progressive loss of function. Therefore, BFR may be a successful option to facilitate strength gains even in patients unable to perform traditional high-load resistance training. Indications: BFR therapy has been shown to be efficacious when used in healthy athletes, the elderly, or in postoperative patients undergoing rehabilitation after upper or lower extremity procedures. More specifically, BFR application in patients undergoing knee surgery has been shown to reduce muscle atrophy post operatively. Technique Description: BFR involves application of a tourniquet or occlusion cuff at 70% of the determined arterial occlusion pressure (commonly 150-180 mm Hg). The arterial occlusion pressure is calculated by observing the loss of Doppler ultrasonography signal at the pedal pulses with sequential inflation of a blood pressure cuff. This cuff should be applied as proximal as possible at the affected extremity. The patient subsequently performs 5 exercises, including 3 sets of 15 repetitions of each exercise, with 30 seconds of rest in between sets. The cuff remains inflated for all 5 exercises. Results: BFR in tandem with low-load resistance training has been shown to be effective in improving lower extremity muscle torque and mass of the quadriceps and hamstring muscles when used after knee surgery, specifically anterior cruciate ligament (ACL) reconstruction. The most commonly reported adverse outcomes after BFR include muscle soreness and sensory paresthesias; however, BFR is generally believed to be safe and acceptable for use in a broad spectrum of patients. Discussion/Conclusion: Muscle atrophy and loss of strength are hallmarks of aging, injured, and postoperative patients. Traditional means of high-intensity strength training is not feasible in these patient populations, and the use of BFR in tandem with lower intensity strength training shows promise in its ability to promote improvements in muscle strength and hypertrophy. However, more high-level research into the long-term effects, complications, and optimal BFR training regimen is warranted. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Application of Current Knowledge of Blood Flow Restriction Training for Use on Upper Extremity Injuries

Blood flow restriction (BFR) utilizes a cuff or tourniquet to induce muscle hypoxia by maintaining arterial flow, while restricting venous return. This technique has recently gained popularity in healthy patients and patients undergoing rehabilitation. Two studies have shown that patients who use BFR, in addition to the standard therapy protocol, following an upper extremity injury (UEI) have reduced pain and improved Patient-Reported Wrist Evaluation scores. The use of BFR in the upper extremity of healthy patients and patients with a prior lower extremity injury have shown statistically significant improvements in muscle strength and muscle hypertrophy. Further studies focusing on BFR training following various upper extremity injuries are needed to determine the potential impact on clinical outcomes. The purpose of this review was to analyze the use of BFR following lower extremity injuries, summarize the literature of BFR for upper extremity injuries, and consider the application of BFR following upper extremity injuries in the future.

Resistance Training with Blood Flow Restriction and Ocular Health: A Brief Review.

Despite the many health benefits of resistance training, it has been suggested that high-intensity resistance exercise is associated with acute increases in intraocular pressure which is a significant risk factor for the development of glaucomatous optic nerve damage. Therefore, resistance training using a variety of forms (e.g., resistance bands, free weights, weight machines, and bodyweight) may be harmful to patients with or at risk of glaucoma. An appropriate solution for such people may involve the combination of resistance training and blood flow restriction (BFR). During the last decade, the BFR (a.k.a. occlusion or KAATSU training) method has drawn great interest among health and sports professionals because of the possibility for individuals to improve various areas of fitness and performance at lower exercise intensities. In comparison to studies evaluating the efficiency of BFR in terms of physical performance and body composition changes, there is still a paucity of empirical studies concerning safety, especially regarding ocular health. Although the use of BFR during resistance training seems feasible for glaucoma patients or those at risk of glaucoma, some issues must be investigated and resolved. Therefore, this review provides an overview of the available scientific data describing the influence of resistance training combined with BFR on ocular physiology and points to further directions of research.

Blood Flow Restriction Therapy for 2 Weeks Prior to Anterior Cruciate Ligament Reconstruction Did Not Impact Quadriceps Strength Compared to Standard Therapy

To evaluate the efficacy of a 2-week home-based blood flow restriction (BFR) prehabiliation program onquadriceps strength and patient-reported outcomes prior to anterior cruciate ligament (ACL) reconstruction. Patients presenting with an ACL tear were randomized into two groups, BFR and control, at their initial clinic visit. Quadriceps strength was measured using a handheld dynamometer in order to calculate peak force, average force, and time to peak force during seated leg extension at the initial clinic visit and repeated on the day of surgery. All patients were provided education on standardized exercises to be performed 5 days per week for 2 weeks between the initial clinic visit and date of surgery. The BFR group was instructed to perform these exercises with a pneumatic cuff set to 80% of limb occlusion pressure placed over the proximal thigh. Patient-Reported Outcome Measurement System Physical Function (PROMIS-PF), knee range of motion, and quadriceps circumference were gathered at the initial clinic visit and day of surgery, and patients were monitored for adverse effects. A total 45 patients met inclusion criteria and elected to participate. There were 23 patients randomized to the BFR group and 22 patients randomized into the control group. No significant differences were noted between the BFR and control groups in any demographic characteristics (48% vs 64% male [P= .271] and average age 26.5 ± 12.0 vs 27.0 ± 11.0 [P= .879] in BFR and control, respectively). During the initial clinic visit, there were no significant differences in quadriceps circumference, peak quadriceps force generation, time to peak force, average force, pain, and PROMIS scales (P > .05 for all). Following completion of a 2-week home prehabilitation protocol, all patients indeterminant of cohort demonstrated decreased strength loss in the operative leg compared to the nonoperative leg (P < .05 for both) However, there were no significant differences in any strength or outcome measures between the BFR and control groups (P > .05 for all). There were no complications experienced in either group, and both were compliant with the home-based prehabilitation program. A 2-week standardized prehabilitation protocol preceding ACL reconstruction resulted in a significant improvement in personal quadriceps peak force measurements, both with and without the use of BFR. No difference in quadriceps circumference, strength, or patient reported outcomes were found between the BFR and the control group. The home-based BFR prehabiliation protocol was found to be feasible, accessible, and well tolerated by patients. Level II, randomized controlled trial with small effect size.

Poster 178: Blood Flow Restriction Therapy Before and After Arthroscopic Rotator Cuff Repair

Objectives:To evaluate the effect of blood flow restriction (BFR) therapy conducted before and after rotator cuff repair (RCR) on rotator cuff strength and patient reported outcomes.Methods:A total of 30 patients (22 male, 8 female; age 58.2 ± 9.0 years) presenting for surgical treatment of a rotator cuff tear were randomized into two groups, BFR (N=15) and Control (N=15). Rotator cuff strength was measured utilizing a handheld dynamometer in order to calculate peak force, average force and time to peak force. Strength measurements included supraspinatus, infraspinatus and subscapularis testing in multiple positions. Prior to surgery, patients completed a rotator cuff strengthening program, with and without the use of BFR. All patients underwent arthroscopic RCR and a standardized period of post-operative immobilization. Following surgery, patients underwent physical therapy utilizing standard post-RCR therapy protocols, with exercises performed with and without the use of BFR in each respective group. The BFR group was instructed to perform these exercises with a pneumatic cuff set to 80% of limb occlusion pressure placed over the proximal arm, under the direction of a physical therapist. Patient Reported Outcome Measurement System Upper Extremity (PROMIS-UE), American Shoulder and Elbow Surgeons (ASES) score and shoulder range of motion were collected on the day of surgery as well as 2 weeks, 6 weeks and 3 months after surgery. Rotator cuff strength measurements were completed the day of surgery and repeated three months following RCR.Results:No significant differences were noted between the BFR and control groups in peak rotator cuff muscle force generation, time to peak force or average force at any timepoints (P>0.05). At six weeks post-surgery, the BFR group had significantly higher PROMIS-UE scores (30.3 ± 4.7 versus 26.3 ± 6.3, p=0.03, Figure 1) and active range of motion in abduction (82.4º ± 24.7 versus 65.1º ± 18.8, p=0.03) compared to the control group. These differences were not apparent at 3 month follow up.Conclusions:Blood flow restriction therapy following RCR results in improved patient reported outcomes scores and range of motion at six week follow up. At three months post-surgery, there was no noted improvement in rotator cuff strength when utilizing BFR compared to standard physical therapy.

A narrative review of the effects of blood flow restriction on vascular structure and function.

Blood flow restriction is growing in popularity as a tool for increasing muscular size and strength. Currently, guidelines exist for using blood flow restriction alone and in combination with endurance and resistance exercise. However, only about 1.3% of practitioners familiar with blood flow restriction applications have utilized it for vascular changes, suggesting many of the guidelines are based on skeletal muscle outcomes. Thus, this narrative review is intended to explore the literature available in which blood flow restriction, or a similar application, assess the changes in vascular structure or function. Based on the literature, there is aknowledge gap in how applying blood flow restriction with relative pressures may alter the vasculature when applied alone, with endurance exercise, and with resistance exercise. In many instances, the application of blood flow restriction was not in accordance with the current guidelines, making it difficult to drawdefinitive conclusions as to how the vascular system would be affected. Additionally, several studies report no change in vascular structure or function, but few studies look at variables for both outcomes. By examining outcomes for both structure and function, investigators would be able to generate recommendations for the use of blood flow restriction to improve vascular structure and/or function in the future.

Augmented muscle deoxygenation during repeated sprint exercise with post‐exercise blood flow restriction

Blood flow restriction (BFR) during low‐intensity exercise has been known to be a potent procedure to alter metabolic and oxygen environments in working muscles. Moreover, the use of BFR during inter‐set rest periods of repeated sprint exercise has been recently suggested to be a potent procedure for improving training adaptations. The present study was designed to determine the effect of repeated sprint exercise with post‐exercise BFR (BFR during rest periods between sprints) on muscle oxygenation in working muscles. Eleven healthy males performed two different conditions on different days: either repeated sprint exercise with BFR during rest periods between sets (BFR condition) or without BFR (CON condition). A repeated sprint exercise consisted of three sets of 3 × 6‐s maximal sprints (pedaling) with 24s rest periods between sprints and 5 min rest periods between sets. In BFR condition, two min of BFR (100–120 mmHg) for both legs was conducted between sets. During the exercise, power output and arterial oxygen saturation (SpO2) were evaluated. Muscle oxygenation for the vastus lateralis muscle, exercise‐induced changes in muscle blood flow, and muscle oxygen consumption were measured. During BFR between sets, BFR condition presented significantly higher deoxygenated hemoglobin + myoglobin (p < 0.01) and lower tissue saturation index (p < 0.01) than those in CON condition. However, exercise‐induced blood lactate elevation and reduction of blood pH did not differ significantly between the conditions. Furthermore, power output throughout nine sprints did not differ significantly between the two conditions. In conclusion, repeated sprint exercise with post‐exercise BFR augmented muscle deoxygenation and local hypoxia, without interfering power output.