Blood Flow Restriction Training After Achilles Tendon Rupture

Blood flow restriction training for an individual with Kellgren-Lawrence grade 4 ankle osteoarthritis following childhood clubfoot repair: A case report

BACKGROUND

Ankle osteoarthritis (OA) is a disease involving pain and decreased physical function which can attenuate the tolerance to perform high-load resistance training. Low-load blood flow restriction (BFR) training has been demonstrated to improve muscle strength, muscle size, and physical function in patients suffering from OA.

OBJECTIVE

We examined the effects of 12 weeks of BFR-training performed 4 times a week in an individual with Kellgren-Lawrence (KL) grade 4 ankle OA.

CASE DESCRIPTION

A 32-year-old woman with KL grade 4 right ankle OA subsequent to a clubfoot repair in childhood performed 12 weeks of BFR-training. Four exercises with concurrent blood flow restriction (60% of arterial occlusion pressure) targeting the lower leg were performed 4 times/week. The following outcome measures were collected at baseline and 12 weeks after BFR-training: The Foot and Ankle Outcome Score (FAOS), calf circumference, maximal isometric muscle strength, single-leg heel raise test, single-leg stance test, and lateral side-hop test.

OUTCOMES

Adherence to the training was 93.75%. The patient demonstrated improvements in FAOS subscale symptoms, pain, and sports/recreational activities by 19-47 points (minimal detectable change (MDC) = 18-21.5 points); maximal muscle strength in plantarflexion (36%), eversion (55%), and inversion (38%) (MDC for plantarflexion = 16.81-29.97%). The single-leg heel raise test and the lateral side-hop test improved with 66% and 51%, respectively. Calf circumference was maintained.

CONCLUSION

BFR-training improved patient-reported outcomes, lower leg muscle strength, and physical function in an individual suffering from KL grade 4 ankle OA following childhood clubfoot repair.

Survey of Blood Flow Restriction Training Applications in Sports Medicine and Performance Practice Across North America

Colapietro, MA, Lee, JZ, and Vairo, GL. Survey of blood flow restriction training applications in sports medicine and performance practice across North America. J Strength Cond Res 38(5): 856–863, 2024—This study profiled current clinical applications of blood flow restriction (BFR) training and observed side effects by surveying active sports medicine and performance personnel across North America. An online survey consisting of questions derived from a related position statement was distributed through professional organizations, email listservs, and social media. Personnel with experience applying or prescribing BFR training with permanent residence within the United States or Canada were eligible to participate. Variables captured included demographics (profession, practice setting), BFR equipment, treatment parameters, observed side effects, and personal perceptions regarding BFR training. An alpha level of p < 0.05 determined significance. A convenience sample included 72 clinicians with 67 being from the United States. Athletic trainers (n = 35) and physical therapists (n = 30) primarily participated. Chi-square test of independence indicated that a higher proportion of physical therapists (90.3%) report receiving formal education in BFR training compared with athletic trainers (65.7%) ( = 4.1, p = 0.043). Parameters varied between respondents for exercise prescription and occlusion settings. Respondents primarily followed position statement recommendations with individualized pressure selections for resistance (80.9%) and aerobic (84.8%) BFR modes. Side effects reported included delayed onset muscle soreness (66.2%), inability to continue because of pain (28%), and numbness (22.5%). Personal perceptions between athletic trainers and physical therapists were compared using independent t-tests. Physical therapists indicated higher confidence in safety (difference = 0.37 ± 0.32, p = 0.026), understanding recommendations (difference = 0.47 ± 0.37, p = 0.011), and theoretical principles (difference = 0.80 ± 0.53, p = 0.004). Despite variation in BFR parameters used, sports medicine personnel demonstrate compliance with position statement recommendations and report mild side effects.

Blood flow restriction training does not negatively alter the mechanical strength or histomorphology of uninjured equine superficial digital flexor tendons

BACKGROUND

Low load exercise training with blood flow restriction (BFR) has become increasingly used by human physical therapists to prescribe controlled exercise following orthopaedic injury; its effects on the equine superficial digital flexor tendon (SDFT), however, are unknown.

OBJECTIVE

To investigate outcomes of pressure specific BFR walking exercise on uninjured equine SDFT biomechanics and histomorphology.

STUDY DESIGN

Controlled in vivo experiment.

METHODS

Four forelimbs of four horses were exposed to 40 BFR-walk sessions (10-min interval walking) on a treadmill over a 56-day study period with their contralateral forelimbs serving as untreated controls. Similarly, four forelimbs of four control horses were exposed to 40 sham cuff walk sessions. On study Day 56, all horses (n = 8) were humanely euthanised and forelimb SDFTs underwent non-destructive biomechanical testing and corresponding histomorphological analysis. Significance in biomechanical parameters between treatment groups was analysed using a mixed-effects ANOVA with Tukey's post-hoc tests.

RESULTS

Statistically significant differences in SDFT stiffness for both first (p = 0.02) and last cycles (p = 0.03) were appreciated within the BFR treated group only, with BFR exposed forelimbs being significantly stiffer than the contralateral unexposed forelimbs. When normalised to cross-sectional area, no significant differences were appreciated among treatment groups in elastic modulus for the first (p = 0.5) or last cycles (p = 0.4). No histological differences were appreciated among treatment groups according to Bonar, Movin, or musculotendinous junction evaluation criteria.

MAIN LIMITATIONS

Short-term comparisons were performed in a small sample population without correlation to performance outcome measures. Optimal occlusion percentages and walk protocols remain unknown.

CONCLUSIONS

This study demonstrated no negative impact of BFR on mechanical strength of the equine SDFT; however, evidence suggests that BFR results in increased tendon stiffness based on biomechanical testing and subsequent calculations. No consistent detrimental histomorphological changes were seen.

Effect of Low-Load Blood Flow Restriction Training on Patients With Functional Ankle Instability: A Randomized Controlled Trial

CONTEXT

Decreased muscle strength and balance in patients with functional ankle instability (FAI) can be effectively improved by ankle strength training. Low-load blood flow restriction (LL-BFR) training increases muscle size and strength, but there is limited evidence from studies on muscle strength and balance in FAI patients.

OBJECTIVE

To study the effects of LL-BFR training versus high-load training (HLT) on muscle strength and balance in FAI patients.

DESIGN

Randomized controlled trial.

PARTICIPANTS

Forty-six young adults with a history of FAI.

INTERVENTIONS

Participants in the LL-BFR and HLT groups performed 4 sets (30 × 15 × 15 × 15) of ankle training at 20% to 40% of the one-repetition maximum and 70% to 85% one-repetition maximum, respectively, twice a week for 6 weeks.

MAIN OUTCOME MEASURE(S)

Plantar flexion, dorsiflexion, inversion, and eversion muscle strength, and the Y-balance test scores were assessed at baseline and after 3 and 6 weeks; the thickness of the tibialis anterior, triceps surae, and peroneus longus muscles were assessed at baseline and after 6 weeks.

RESULTS

Inversion, eversion, dorsiflexion, and plantar flexion muscle strength; tibialis anterior, triceps surae, and peroneus longus thickness; and Y-balance test scores were significantly increased in the LL-BFR group after 3 and 6 weeks compared with baseline (P < .05), with no significant difference between the LL-BFR and HLT groups after 6 weeks (P > .05). However, at the end of 3 weeks, eversion muscle strength and Y-balance test scores were significantly higher in the LL-BFR group than in the HLT group (P < .05).

CONCLUSIONS

Over 6 weeks, LL-BFR training was as effective as HLT in improving ankle muscle strength, muscle thickness, and balance in FAI patients, but LL-BFR training improved the ankle eversion muscle strength and dynamic balance more than HLT did in the early stages of the intervention. This finding will provide a new intervention strategy for the clinical rehabilitation of FAI patients.

Equine blood flow restriction training: Safety validation

BACKGROUND

Blood flow restriction (BFR) has become a key rehabilitative tool for human orthopaedic conditions. With modernised technology and evolution of clinical application, patient-specific delivery of occlusion percentages is now considered the standard of care in human patients due to improved therapeutic outcomes and minimised safety risks. Safety validation and limb occlusion pressure (LOP) data for horses, however, are lacking.

OBJECTIVE

(1) To determine if BFR exposure resulted in forelimb biomechanical gait dysfunction as safety validation and (2) to investigate inter-horse and inter-limb LOP differences.

STUDY DESIGN

Controlled in vivo experiment.

METHODS

Daily unilateral forelimb BFR was performed in four horses over 56 days. Clinical examinations and objective gait analyses were performed on Days 0, 28 and 56. Daily LOP values were determined by Doppler evaluation to deliver 80% vascular occlusion at a walk. A linear mixed model evaluated for differences in lameness, kinetic and kinematic gait parameters.

RESULTS

There were no significant differences in forelimb lameness (range of Grades 0-2 across all forelimbs), kinematic or kinetic gait parameters over time or between BFR-exposed and control (contralateral) limbs (p > 0.05). Clinically apparent complications related to BFR such as thrombosis or dermatitis were not appreciated. Significant differences in mean LOP values between various horses (p < 0.001) and measured left (204.48 mmHg) and right (173.78 mmHg) forelimbs (p < 0.001) were observed. Mean LOP and standard deviation across all readings was 189.1 ± 22.2 mmHg.

MAIN LIMITATIONS

Optimal BFR occlusion percentages and protocols with documented clinical efficacy are unknown. Small study population.

CONCLUSIONS

Exposure to BFR did not result in forelimb biomechanical dysfunction in four horses. Applied pressures of 75-151 mmHg would likely simulate a range of 50%-80% vascular occlusion in horses, but inherent physiological variation between horses and forelimbs warrants incorporation of individual pressures.

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

Background

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).

Hypothesis

The indication and protocol for BFR therapy vary significantly across providers in the US.

Methods

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.

Results

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.

Conclusion

BFR therapy has increased in popularity with most physicians implementing its use in the last 5 years. BFR was commonly utilized after ACLR.

Clinical relevance

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.

Knee Loading With Blood Flow Restriction Can Enhance Recovery After Total Knee Arthroplasty

Total knee arthroplasty (TKA) is one of the most performed operations in the world, especially in the elderly. Aging has a significant effect on joint cartilage, muscle strength, and muscle mass. Following a TKA, despite the significant reduction of symptoms and the improvement in mobility, muscle strength and muscle mass recovery remains a significant challenge. Restrictions that arise from the surgical procedure include joint loading, functional activities, and range of motion, along with limitations related to the age of the individual and their previous loading history, these are the significant restrictions, at least in the early stages of rehabilitation. Evidence indicates that blood flow restriction (BFR) training has significant potential to enhance recovery via implementation of low-load or low-intensity exercise. While respecting the indications and contraindications related to BFR application, the optimization of metabolic stress seems to offer a bridging therapy to heavy load while reducing pain and inflammation. Thus, the combination of BFR and low loads may improve muscular recovery (strength and mass), and aerobic training protocols appear to show significant enhancement of multiple cardiopulmonary parameters. Mounting evidence, direct and indirect, indicate that BFR training may have the potential to benefit the pre-operative and post-operative TKA rehabilitation phases and enhance functional recovery and physical abilities in the elderly.

The effects of upper body blood flow restriction training on muscles located proximal to the applied occlusive pressure: A systematic review with meta-analysis

BACKGROUND

Blood flow restriction combined with low load resistance training (LL-BFRT) is associated with increases in upper limb muscle strength and size. The effect of LL-BFRT on upper limb muscles located proximal to the BFR cuff application is unclear.

OBJECTIVE

The aim of this systematic review was to evaluate the effect of LL-BFRT compared to low load, or high load resistance training (LL-RT, HL-RT) on musculature located proximal to cuff placement.

METHODS

Six electronic databases were searched for randomized controlled trials (RCTs). Two reviewers independently evaluated the risk of bias using the PEDro scale. We performed a meta-analysis using a random effects model, or calculated mean differences (fixed-effect) where appropriate. We judged the certainty of evidence using the GRADE approach.

RESULTS

The systematic literature searched yielded 346 articles, of which 9 studies were eligible. The evidence for all outcomes was of very low to low certainty. Across all comparisons, a significant increase in bench press and shoulder flexion strength was found in favor of LL-BFRT compared to LL-RT, and in shoulder lean mass and pectoralis major thickness in favor of the LL-BFRT compared to LL-RT and HL-RT, respectively. No significant differences were found between LL-BFRT and HL-RT in muscle strength.

CONCLUSION

With low certainty LL-BFRT appears to be equally effective to HL-RT for improving muscle strength in upper body muscles located proximal to the BFR stimulus in healthy adults. Furthermore, LL-BFRT may induce muscle size increase, but these adaptations are not superior to LL-RT or HL-RT.

Current Consensus for Rehabilitation Protocols of the Surgically Repaired Acute Mid-Substance Achilles Rupture: A Systematic Review and Recommendations From the "GAIT" Study Group

Surgical repair of acute mid-substance Achilles tendon ruptures is performed in active patients, but the postoperative rehabilitation program is often based on the experience of the surgeon or therapist, rather than on evidence-based protocols. The aim of the study is to establish an evidence-based protocol for rehabilitation. This study is a consensus statement. The "GAIT" study group (German, American, and Italian Tendon), an informal collection of 4 experienced foot and ankle surgeons, met to address the question of what items they felt were important relative to rehabilitate a surgically repaired Achilles tendon acute rupture. Thirty-three statements were formulated. A value of 100% agreement by all the members was set to produce a proposed consensus statement. A value of 80% consensus was set to produce "strong recommendation." A systematic review of the literature was also performed. The GAIT group reach 100% agreement on the average postoperative non-weightbearing for 2.3 weeks, the foot in plantarflexion for the first 4 weeks, avoiding ROM exercises beyond neutral, and both stretching and eccentric exercise, not started before 12 weeks. Concentric bilateral heel raises should be performed after 6 weeks, and the average return to initiate sports, was 24.4 weeks. The use of a 1/8^th-1/4^th inch heel cushions in daily shoes after 8 weeks, the use of an antigravity treadmill for rehabilitation, and the return to sports based on heel raise repetitions is strongly recommended. Given lack of established verified protocols, the recommendations by our experienced panel should be considered. These proposed consensus statements could be used as a basis for larger controlled trials, and develop best practices.

Blood Flow Restriction Resistance Training in Tendon Rehabilitation: A Scoping Review on Intervention Parameters, Physiological Effects, and Outcomes

Objective

To identify current evidence on blood flow restriction training (BFRT) in tendon injuries and healthy tendons, evaluating physiological tendon effects, intervention parameters, and outcomes.

Methods

This scoping review was reported in accordance with the PRISMA Extension for Scoping Reviews (PRISMA-ScR). Databases searched included MEDLINE, CINAHL, AMED, EMBase, SPORTDiscus, Cochrane library (Controlled trials, Systematic reviews), and five trial registries. Two independent reviewers screened studies at title/abstract and full text. Following screening, data was extracted and charted, and presented as figures and tables alongside a narrative synthesis. Any study design conducted on adults, investigating the effects of BFRT on healthy tendons or tendon pathology were included. Data were extracted on physiological tendon effects, intervention parameters and outcomes with BFRT.

Results

Thirteen studies were included, three on tendinopathy, two on tendon ruptures, and eight on healthy Achilles, patellar, and supraspinatus tendons. A variety of outcomes were assessed, including pain, function, strength, and tendon morphological and mechanical properties, particularly changes in tendon thickness. BFRT intervention parameters were heterogeneously prescribed.

Conclusion

Despite a dearth of studies to date on the effects of BFRT on healthy tendons and in tendon pathologies, preliminary evidence for beneficial effects of BFRT on tendons and clinical outcomes is encouraging. As BFRT is a relatively novel method, definitive conclusions, and recommendations on BFRT in tendon rehabilitation cannot be made at present, which should be addressed in future research, due to the potential therapeutic benefits highlighted in this review.

Acute Achilles Tendon Rupture Repair in Athletically Active Patients: Results on 188 Tendons

We report on the outcome of acute Achilles tendon ruptures by a single surgeon using open and percutaneous techniques was performed. This prospective study included 186 patients with 188 ruptured Achilles tendons. A traditional open technique was primarily performed on patients from January 2001 to December 2011. From January 2012 to January 2018, a percutaneous repair was primarily performed. Outcome measures included the Roles and Maudsley (RM) score, ability to perform a single leg heel raise, calf atrophy and return to activity. There were 149 males (average age 42.5 ± 12.7 years) and 39 females (average age 41.7 ± 11.4 years). Of the 188 ruptured tendons (92 repairs on the right Achilles and 96 on the left), 103 were repaired percutaneously and 85 had open repairs. There were 18 (9.6%) complications. Three re-ruptures occurred, one following open and two following percutaneous repairs, all within 12 weeks of the original repair. Two patients developed a Venousthromboembolism (1.0%). Thirteen patients had suture reactions; three infections (1.6%), 11 wound complications (5.8%), and 3 required surgical excision of the suture material (1.6%). Non-absorbable sutures were associated with more wound complications and were more frequently used in open repairs (p = .003). Patients who underwent open repair experienced more wound complications (p = .0001). Patients who underwent percutaneous repair using absorbable suture experienced a lower rate of overall complications (p = .0007). Basketball (n = 29) was the most common sport during which ruptures occurred. Return to activity (RTA) was 8.2 ± 2.9 months. There was no difference for RTA between males and females (p = .54) and RM scores (p= .69), nor surgical technique, and no difference for RTA based on the desired activity (p = .47). 123 of the 188 patients returned to their desired activity (65.5%). There was a statistically significant evidence of a positive association between inability to perform heel-raises and decreased activity (p = .01).

Acute Effects of Resistance Training with Blood Flow Restriction on Achilles Tendon Thickness

The Achilles tendon is one of the strongest and thickest tendons of the human body. Several studies have reported an immediate decrease in Achilles tendon thickness after a single bout of resistance training. However, the effects of blood flow restriction training on Achilles tendon thickness have not been investigated. The purpose of this study was to investigate the acute effects of different regimens of resistance training on Achilles tendon thickness. Fiftytwo participants (27.3 ± 7 years; 177.6 ± 11 cm; 72.2 ± 13.7 kg) were randomly allocated into one of the three groups: low-intensity exercise without (LI, n = 13) and with blood flow restriction (LI-BFR, n = 24), and high-intensity exercise (HI, n = 15). Participants from LI and LI-BFR groups performed four sets (1 x 30 + 3 x 15 reps) at 30% 1RM, while the HI group performed four sets (1 x 30 with 30% 1RM + 3 x 10 reps with 75% 1RM). All groups performed a plantar flexion exercise. For the LI-BFR group, a blood pressure cuff was placed on the dominant calf and inflated at 30% of the individual´s occlusion pressure (47.6 ± 19.8 mmHg). Sonographic images of Achilles tendon thickness were taken at pre, immediately after, 60 min and 24 h following acute bouts of exercise. Achilles tendon thickness was significantly reduced immediately after, 60 min and 24 h post-LI-BFR exercise (pre: 4.4 ± 0.4 mm vs. IA: 3.8 ± 0.4 mm vs. 60 min: 3.7 ± 0.3 mm vs. 24 h: 4.1 ± 0.3 mm; p < 0.001), whereas Achilles tendon thickness was unchanged for HI and LI groups (p > 0.05). These results suggest that blood flow restriction training may be an effective strategy to stimulate a positive response in Achilles tendon thickness.

Acute Hamstring Muscle Tears in Climbers-Current Rehabilitation Concepts

Acute hamstring injuries are often caused by the heel hook technique. This technique is unique to climbing and causes injury to muscular and inert tissues of the posterior thigh. The heel hook is used by climbers during strenuous ascent on overhanging walls and when crossing difficult terrain. The technique reduces the amount of upper body strength required during strenuous climbing because the climber's center of mass is retained within the base of support. The heel hook is stressful collectively for the hamstring muscle group and musculotendinous junction. Depending on injury severity, both conservative and surgical methods exist for the management of hamstring injuries. Contemporary approaches to rehabilitation primarily advocate the use of eccentric muscle strengthening strategies because of high rates of elongation stress associated with sprinting and team sports. However, there is reason to doubt whether this alone is sufficient to rehabilitate the climbing athlete in light of the high degree of concentric muscle strength required in the heel hook maneuver. This review examines the contemporary rehabilitation and strength and conditioning literature in relation to the management of acute hamstring musculotendinous injuries for the climbing athlete. The review provides a comprehensive approach for the rehabilitation and athletic preparation of the climbing athlete from the initial injury to full return to sports participation.

Local and Systemic Effects of Blood Flow Restriction Therapy in an Animal Model

BACKGROUND

Blood flow restriction therapy (BFRT) has been increasingly applied to improve athletic performance and injury recovery. Validation of BFRT has lagged behind commercialization, and currently the mechanism by which this therapy acts is unknown. BFRT is one type of ischemic therapy, which involves exercising with blood flow restriction. Repetitive restriction of muscle blood flow (RRMBF) is another ischemic therapy type, which does not include exercise.

HYPOTHESIS/PURPOSE

The purpose was to develop a rat model of ischemic therapy, characterize changes to muscle contractility, and evaluate local and systemic biochemical and histologic responses of 2 ischemic therapy types. We hypothesized that ischemic therapy would improve muscle mass and strength as compared with the control group.

STUDY DESIGN

Controlled laboratory study.

METHODS

Four groups of 10 Sprague-Dawley rats were established: control, stimulation, RRMBF, and BFRT. One hindlimb of each subject underwent 8 treatment sessions over 4 weeks. To simulate exercise, the stimulation group underwent peroneal nerve stimulation for 2 minutes. The RRMBF group used a pneumatic cuff inflated to 100 mm Hg with a 48-minute protocol. The BFRT group involved 100-mm Hg pneumatic cuff inflation and peroneal nerve stimulation for a 5-minute protocol. Four methods of evaluation were performed: in vivo contractility testing, histology, immunohistochemistry, and ELISA. Analysis of variance with post hoc Tukey test and linear mixed effects modeling were used to compare the treatment groups.

RESULTS

There was no difference in muscle mass among groups (P = .40) or between hindlimbs (P = .73). In vivo contractility testing showed no difference in maximum contractile force among groups (P = .64) or between hindlimbs (P = .30). On histology, myocyte cross-sectional area was not different among groups (P = .55) or between hindlimbs (P = .44). Pax7 immunohistochemistry demonstrated no difference in muscle satellite cell density among groups (P = .06) or between hindlimbs (P = .046). ELISA demonstrated the RRMBF group as eliciting elevated GH levels as compared with the other groups (P < .001).

CONCLUSION

Ischemic therapy did not induce gains in muscle mass, contractility strength, fiber cross-sectional area, or satellite cell density locally or systemically in this model, although the RRMBF group did have elevated GH levels on ELISA.

CLINICAL RELEVANCE

This animal model does not support ischemic therapy as a method to improve muscle mass, function, or satellite cell density.

Management of Achilles Tendon Injuries in the Elite Athlete

The management of Achilles tendon rupture continues to be controversial in the everyday athlete; however, there is strong evidence indicating that surgical intervention is preferred in elite athletes due to the return of greater strength and peak torque. We review the published literature, as well as our operative technique and post-operative protocol in the management of Achilles tendon injuries in elite athletes.

Ischemic Therapy in Musculoskeletal Medicine

BACKGROUND

The competitive environment of athletics has promoted the exploration of any technology application that may offer an edge with performance and recovery from injury. Ischemic therapy is one such technology that has rapidly been incorporated into training rooms and physical therapy clinics worldwide. This therapy modality is reported to increase an athlete's ability to improve muscle mass, strength, and endurance.

PURPOSE

To provide the sports medicine physician with an understanding of the current state of ischemic therapy technology, including treatment specifications, known physiological effects, hypothesized mechanisms, biochemical effects, athletic applications, medical applications, animal models, and future research recommendations.

STUDY DESIGN

Literature review.

METHODS

A computer-based search of the PubMed database was used to perform a comprehensive literature review on musculoskeletal ischemic therapy.

RESULTS

The current research on ischemic therapy is largely composed of case series with varying equipment, methods, and therapy specifications. The publication of case series has value in identifying this technology for future research, but the results of these studies should not be justification for application to athletes without validation of safety and effectiveness.

CONCLUSION

To date, ischemic therapy remains unvalidated, and the mechanism by which it improves muscle performance is not clear.

Safety and Efficacy of Blood Flow Restriction Therapy after Operative Management of Distal Radius Fractures: A Randomized Controlled Study

Background  Blood flow restriction (BFR) therapy is an emerging addition to rehabilitative programs that allows patients to increase strength at lower loads over shorter time periods. Therefore, we conducted a study to evaluate the safety and efficacy of a rehabilitation program using BFR to a traditional rehabilitation protocol following operative fixation of distal radius fractures. Methods  A randomized controlled study was conducted comparing a standardized rehabilitation protocol alone to a combined protocol with the use of BFR therapy in patients treated with volar plate fixation following a displaced distal radius fracture. The same exercises done in the control group were performed by the BFR group with a restrictive tourniquet in place. Patients were followed with serial radiographs to ensure fracture stability. Outcome measures included wrist range of motion, grip strength, pinch strength, visual analog scale (VAS) pain scores at rest and during activity, patient rated wrist evaluation scores (PRWE), and disabilities of the arm, shoulder, and hand scores. Results  Nine patients were randomized and enrolled within the BFR group ( n  = 5) and control ( n  = 4) groups. Patients within the BFR group had a significantly greater reduction in pain with activity over the course of the rehabilitation program. Additionally, the BFR group had a significant improvement in PRWE scores during the 8-week rehabilitation program. There was no difference in radiographic measures after initiation of BFR, and all patients tolerated therapy without noted complications. Conclusion  BFR therapy is safe and well tolerated after operatively treated distal radius fractures. The addition of BFR therapy can result in quicker reduction in pain with activity and improvement in patient disability when used early following operative management of a distal radius fracture. Level of Evidence  This is a Level 1, prognostic study.

Blood Flow Restriction Therapy: Where We Are and Where We Are Going

Blood flow restriction therapy (BFRT) is an innovative training method for the development of muscle strength and hypertrophy in the athletic and clinical settings. Through the combination of venous occlusion and low-load resistance training, it induces muscle development through a number of proposed mechanisms including anaerobic metabolism, cellular swelling, and induction of type 2 muscle fibers. Muscle weakness and atrophy are prevalent among musculoskeletal rehabilitation patients, causing delayed return to functional activity. In traditional resistance training, muscle development requires exercise loads of 70% of one-repetition maximum (1RM), but the stress placed on connective tissues and joints can be detrimental to the elderly and rehabilitation patients. However, BFRT with loads of 20% to 40% of 1RM has been shown consistently in the literature to increase muscle strength, hypertrophy, and angiogenesis. The rate of adverse effects has not been found to be greater than that in traditional high-load resistance training, but its effects on the cardiovascular system have yet to be evaluated in long-term studies. Although further investigations are needed to determine the exact mechanism and optimal usage, current evidence is promising for the application of BFRT in athletes, rehabilitation patients, and the elderly patients.

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.

Blood Flow Restriction Therapy after Closed Treatment of Distal Radius Fractures

Background  Blood flow restriction (BFR) therapy is an innovative rehabilitative program that enables patients to increase strength at a fraction of the weight typically necessary in endurance exercises. Therefore, we conducted a pilot study evaluating patient outcomes with a BFR therapy program for closed management after a distal radius fracture compared to a traditional rehabilitation protocol. Literature review  A randomized-controlled study was conducted comparing a standardized hand therapy rehabilitation protocol alone to a combined protocol with the use of BFR therapy in patients who were initially treated with closed reduction and short arm cast immobilization for a displaced distal radius fracture between May 1, 2015 and August 1, 2016. BFR therapy was performed with a restrictive tourniquet applied to the upper brachium, performing the same strengthening exercises as the control group but with the restrictive tourniquet in place. Clinical assessment was conducted at 6, 10, and 14 weeks from the date of initial cast immobilization. Outcome measures collected included wrist range of motion; grip strength; pinch strength; visual analogue scale for pain with activity and at rest; patient-rated wrist evaluation (PRWE) scores; and disabilities of the arm, shoulder, and hand scores. Results  Thirteen patients were enrolled and randomized between the BFR ( n  = 6) and control ( n  = 7) groups. The BFR group noted significantly greater reduction in pain with activity compared to the control group after 8 weeks of therapy (Δ -4.0 vs. -2.3, p  = 0.03). Similarly, patients in the BFR group displayed greater reduction in PRWE scores compared to the control group after 8 weeks of BFR therapy (Δ -57.9 vs. 30.8, p  = 0.01). The two groups did not demonstrate any significant difference in radiographic outcomes at any time point or throughout the course of the study. All patients tolerated the BFR therapy program and there were no complications. Clinical relevance  The addition of BFR therapy to the rehabilitative program after closed management of a distal radius fracture is safe, well tolerated by patients, without any deleterious effects on radiographic outcomes. This pilot study noted that BFR therapy in patients with nonoperative distal radius fractures may result in a larger reduction in pain with activity and greater improvement in overall self-perceived function.

Blood Flow Restriction Therapy: From Development to Applications

Blood flow restriction (BFR) has been shown to produce beneficial adaptations to skeletal muscle. These adaptations have been documented in the civilian and military populations. BFR therapy may provide patients a safe method to begin strength training at earlier stages of rehabilitation to allow for earlier and more effective return to activity and improved military readiness. The purpose was to review BFR therapy physiology, complications, side effects, standardized treatment algorithms, and long-term patient outcomes.

Effects of blood flow restriction exercise on hemostasis: a systematic review of randomized and non-randomized trials

Background

Blood flow restriction (BFR) exercise has shown to induce a positive influence on bone metabolism and attenuate muscle strength loss and atrophy in subjects suffering from musculoskeletal weakness. Despite the known benefits of BFR exercise, it remains unclear whether or not the pressurization of blood vessels damages the endothelial cells or increases risk for formation of thrombi. Thus, the effects of BFR exercise on coagulation, fibrinolysis, or hemostasis, remains speculative.

Objective

The aim of the present study was to perform a systematic review of the short and long- term effects of BFR exercise on blood hemostasis in healthy individuals and patients with known disease (ie, hypertension, diabetes, obesity, and ischemic heart disease).

Data Sources

A systematic review of English and non-English articles was conducted across PubMed, Science Direct, and Google Scholar databases, including reference lists of relevant papers. Study quality assessment was evaluated using the modified version of Downs and Black checklist. Search results were limited to exercise training studies investigating the effects of BFR exercise on blood hemostasis in healthy individuals and patients with disease. Level of evidence was determined according to the criteria described by Oxford Center for Evidence-Based Medicine.

Study selection

Only randomized controlled trials (RCTs) and non-randomized controlled trials (NRCTs) that examined the effects of exercise with BFR exercise vs exercises without BFR on blood hemostasis in healthy individuals and patients were included.

Data extraction

Nine studies were eligible (RCT =4; NRCT =5).

Results

The average score on the Downs and Black checklist was 11.22. All studies were classified as having poor methodological quality wherein the level of evidence provided in all reviewed studies was level IIb only (ie, poor quality RCTs).

Conclusion

Considering the limitations in the available evidence, firm recommendations cannot be provided.

Application of Blood Flow Restriction to Optimize Exercise Countermeasures for Human Space Flight

In recent years there has been a strong increase in publications on blood flow restriction (BFR) training. In particular, the fact that this type of training requires only low resistance to induce muscle strength and mass gains, makes BFR training interesting for athletes and scientists alike. For the same reason this type of training is particularly interesting for astronauts working out in space. Lower resistance during training would have the advantage of reducing the risk of strain-induced injuries. Furthermore, strength training with lower resistances would have implications for the equipment required for training under microgravity conditions, as significantly lower resistances have to be provided by the training machines. Even though we are only about to understand the effects of blood flow restriction on exercise types other than low-intensity strength training, the available data indicate that BFR of leg muscles is also able to improve the training effects of walking or running at slow speeds. The underlying mechanisms of BFR-induced functional and structural adaptations are still unclear. An essential aspect seems to be the premature fatigue of Type-I muscle fibers, which requires premature recruitment of Type-II muscle fibers to maintain a given force output. Other theories assume that cell swelling, anabolic hormones, myokines and reactive oxygen species are involved in the mediation of BFR training-related effects. This review article is intended to summarize the main advantages and disadvantages, but also the potential risks of such training for astronauts.

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

Synopsis Restoration of skeletal muscle mass and strength is critical to successful outcomes following orthopaedic surgery. Blood flow restriction (BFR) resistance exercise has emerged as a promising means of augmenting traditional low-intensity physical rehabilitation exercise and has yielded successful outcomes in a wide range of applications. Though BFR is well tolerated and safe for most individuals, patients who have undergone orthopaedic surgery may be an exception, due to their heightened risk for venous thromboembolism (VTE). While the pathogenesis of VTE is multifactorial and specific to the individual, it is commonly described as a combination of blood stasis, endothelial injury, and alterations in the constituents of the blood leading to hypercoagulability. The collective literature suggests that, given the pathogenic mechanisms of VTE, limited use of a wide, partially occluding cuff during resistance exercise should be low risk, and the likelihood that BFR would directly cause a VTE event is remote. Alternatively, it is plausible that BFR may enhance blood flow and promote fibrinolysis. Of greater concern is the individual with pre-existing asymptomatic VTE, which could be dislodged during BFR. However, it is unknown whether the direct risk associated with BFR is greater than the risk accompanying traditional exercise alone. Presently, there are no universally agreed-upon standards indicating which postsurgical orthopaedic patients may perform BFR safely. While excluding all these patients from BFR may be overly cautious, clinicians need to thoroughly screen for VTE signs and symptoms, be cognizant of each patient's risk factors, and use proper equipment and prescription methods prior to initiating BFR. J Orthop Sports Phys Ther 2019;49(1):17-27. Epub 12 Sep 2018. doi:10.2519/jospt.2019.8375.

Personalized Blood Flow Restriction Therapy: How, When and Where Can It Accelerate Rehabilitation After Surgery?

Personalized (based on a percentage of a patient's limb occlusion pressure) blood flow restriction is emerging as a potential advancement in orthopaedic surgery. Safe application of the technology requires the use of medical devices capable of customizing the pressures applied to individual patients. In those circumstances, it is a low risk and noninvasive technique. By limiting muscle atrophy and aiding in the recovery of strength and function, it has the potential to significantly reduce the morbidity from limb trauma and surgery, and aid in achieving a substantially earlier return to full activity.