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Training, Prevention, and Rehabilitation/Section Articles

Use of Blood Flow Restriction Training for Postoperative Rehabilitation

Wilkinson, Brandon G. MD1,2; Donnenwerth, Jesse J. PhD, ATC, LAT3; Peterson, Andrew R. MD, MSPH1,2,4,5

Author Information
Current Sports Medicine Reports: June 2019 - Volume 18 - Issue 6 - p 224-228
doi: 10.1249/JSR.0000000000000604
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Abstract

Introduction

Skeletal muscle adapts rapidly to changes in the mechanical environment. Hypertrophy ensues with strong mechanical stress, while atrophy follows unloading or immobilization. Muscle size and strength fluctuations are of particular interest when treating injured patients, particularly in the recovery and rehabilitation periods. Even short periods of immobilization or unloading can result in substantial muscle atrophy with some reports showing 20% to 30% volume reduction within 3 wk after knee arthroscopy (1). It is well known that prevention of atrophy is associated with early return to athletics and improved overall function (2–7). Specifically, quadriceps rehabilitation has been shown to decrease pain and improve knee joint function after anterior cruciate ligament reconstruction (ACLR) surgery (6). However, a dichotomy exists between restoration of skeletal muscle in healthy noninjured patients and postoperative/injured patients. Campbell et al. (8) in 2013 showed relatively rapid (3 wk) restoration of muscle mass using conventional heavy-load resistance training after immobilizing uninjured patients. Contrastingly, several studies in postoperative patients report significantly longer recovery (9–12), with some reporting persistent atrophy up to 49 months postoperatively (13). The reason for this recovery inequality is not definitively known, but almost certainly involves the fact that postoperative and injured patients are often restricted from, or unable to tolerate, the high-load, high-intensity exercises recommended for inducing muscle hypertrophy (14). For this reason, blood flow restriction (BFR) training is of particular interest in these populations. Most simplistically, BFR, or more traditionally “KAATSU” training, involves complete or partial restriction of blood flow via inflatable bands, tourniquet, elastic band or other device proximal to the targeted muscle groups. Theoretically, BFR works through various mechanisms that allow for the buildup of anabolic metabolites, motor unit recruitment, catecholamine and growth hormone release, and possibly other mechanisms (15–17). However, these mechanisms have limited empiric evidence, and there is some evidence that the same mechanisms may not affect both muscle hypertrophy and strength (18). In general, BFR studies have been promising with multiple studies suggesting that BFR training can attenuate strength loss and/or induce muscle hypertrophy (15,19–30). Although robust research has focused on BFR training and muscle hypertrophy, there is a paucity of data evaluating its clinical use in musculoskeletal rehabilitation and postoperative care. Hughes, (31) in a systematic review and meta-analysis, found 20 studies relating to musculoskeletal rehabilitation with only three addressing postoperative rehabilitation. The authors concluded that BFR is safe and augmentation of low-load rehabilitation training with BFR produces improvements in muscular strength compared with low-load training alone. This makes BFR an attractive option for patients unable to tolerate heavy-load rehabilitation (31). However, the use of BFR in postoperative rehabilitation is poorly studied and available studies are limited by inconsistent BFR protocols. It also is unclear if the mechanisms of action of BFR are the same in the setting of injury or rehabilitation as they are in strength training. The goal of this review is to summarize and review the current literature on postoperative BFR utilization in musculoskeletal injuries and to highlight the deficiencies in the literature regarding the use of BFR in these patient populations.

Background/Rational

BFR training, also called “KAATSU,” “blood flow moderation exercise,” “vascular occlusion training,” or “vascular restriction training,” involves partial vascular occlusion by application of a tourniquet, elastic band, or other pressurized cuff with the goal or producing venous occlusion while maintaining arterial blood flow (21). KAATSU, defined as blood flow moderation training, was birthed in Japan in 1966 (32) when Yoshiaki Sato noticed swelling and discomfort in his leg muscles while sitting in traditional Japanese posture that he noted to be similar to the swelling and discomfort he felt during weight lifting. Over years of experimentation with bicycle tubes, ropes, bands, and different occlusion pressures, Sato gradually developed effective protocols for KAATSU training. In 1973, at the age of 25 years, Sato reports sustaining bilateral ankle fractures and a right knee medial collateral ligament injury in a ski accident. Placed in casts, Sato performed KAATSU therapy for 2 wk at which point the treating physician was surprised to see significant hypertrophy of the injured legs. In 1983, KAATSU training methods were generalized for public use (32). Stemming from Sato’s findings, an outburst of research ensued worldwide with predominance among Japanese investigators. BFR training has become increasingly popular over the last decade. To be clear, although the KAATSU method was the first popular BFR restriction system on the market and the authors have personal experience using the KAATSU Nano system (KAATSU Global, Inc), there is no evidence that one BFR system is superior to others.

The muscle atrophy and weakness associated with many musculoskeletal conditions is well described. These degenerative effects are most commonly seen in acute injuries requiring prolonged immobilization, but are often a result of chronic injury (33), or in older populations due to sarcopenia stemming from aging muscle resistance to anabolic stimuli (34). Previous research has shown improved outcomes with effective use of muscle strengthening — specifically, quadriceps strengthening in osteoarthritis has been shown to decrease symptoms in knee osteoarthritis (35), preserve lateral compartment patella-femoral joint space, and decrease knee pain and improve physical function over follow-up (36). The importance of muscle strengthening as a core rehabilitation technique is not new. Historically, muscle hypertrophy regimens consisted of heavy loads requiring upwards of 70% of one-repetition maximum (1RM) (37). Traditional techniques also are used in the elderly to combat age-related muscle strength and mass loss. However, heavy load resistance training rivaling 70% of 1RM is inherently difficult in certain musculoskeletal conditions and patient populations. To overcome this issue, recent research has focused heavily on the effects of low-load training regimens with some studies suggesting low load training to failure can indeed produce muscle hypertrophy comparable in magnitude to heavy load regimens when used three times per week (38,39). However, these same studies ultimately suggest that maximal strength and hypertrophy are achieved through heavy-load training. Nonetheless, these results appear promising, particularly for the care of the postoperative patient (especially in anterior cruciate ligament injury/repair where quad strengthening is paramount), elderly, or injured patients where low-load training to failure may feasibly offset muscle atrophy and weakness in the rehabilitation period. One potential tool to improve muscle size and strength in this setting is low-load training with BFR. Although definitive mechanisms for hypertrophy in BFR are unclear, leading theories suggest that reduction in blood flow to working skeletal muscle creates a hypoxic environment that stimulates muscle hypertrophy and increased muscle strength (23–26). Other suggested mechanisms relate to metabolic stress leading to systemic hormone production, metabolite build-up, (40) increased reactive oxygen species, (21,41) Type II fast-twitch muscle fiber recruitment, (42,43) muscle damage, (44,45) and cell swelling (46). It is likely a conglomeration of mechanisms working synergistically to produce the desired response (31,47). Ironically, despite the concentration of research on BFR in terms of mechanistic studies, there remains a startling paucity of studies focusing on BFR in the postoperative musculoskeletal population. To date, no single definitive mechanism has been proven and continued work is warranted. Research to this point has, however, provided information with important implications regarding rehabilitation in individuals unable to achieve or tolerate heavy-load exercise and the associated mechanical stress. Practically speaking, low-load BFR therapy seems to have the potential to provide significant rehabilitation power while eliminating high joint forces, over exertion, mechanical stresses and heavy-loads (48,49). Although the use of BFR is well described, there remains a paucity of data in its use or effectiveness in the postoperative rehabilitation.

Current Literature

Review of the literature evaluating BFR in the rehabilitation of postoperative patients with musculoskeletal injuries proved scarce — yielding only five studies (Table) There were three controlled trials, one pilot study, and one case report. Four investigations looked at postoperative ACLR, while the remaining study looked at postoperative BFR following knee arthroscopy. The first study from Takarada et al. (19) included 16 patients and evaluated BFR in isolation, without resistance training, starting postoperative day 3 after ACLR. There were two groups: experimental group subjected to twice daily BFR treatments with occlusive pressure 180 to 238 mm Hg for five applications of 5-min occlusion periods with 3-min reperfusion periods in between. Control group consisted of a sham application where the cuff was placed on the thigh, but not inflated. BFR and sham application continued from postoperative day 3 to postoperative day 14. Thigh cross-sectional area (CSA) was determined using magnetic resonance imaging (MRI) on the third and fourteenth postoperative days. Authors noted a significant reduction in atrophy of the knee extensors in the BFR group compared with the control (9.4% and 21%, respectively). There also was a reduction in atrophy of knee flexors (9.2% and 11.3%, respectively) although the difference proved insignificant was not significant (P = 0.69).

Table
Table:
Current literature evaluating BFR in the rehabilitation of postoperative patients with musculoskeletal injuries.

In 2003, Ohta et al. (49) in a randomized controlled trial looked at the effects of low-load resistance training with BFR after ACLR. Forty-four patients (mean age, 29 years) were included and randomized to BFR plus low-load resistance training or low-load resistance training only for 16 wk after semitendinosus autograft ACLR. Outcome measures included thigh CSA (MRI), knee torque, and histologic evaluation of Type I and Type II muscle fiber (vastus lateralis) size changes. The authors noted that at 16 wk, there were significant increases in knee extensor strength, thigh CSA and size of Type I and Type II muscle fibers in the BFR group compared to the controls.

Lejkowski et al. (50) reported a case of vascular restriction training in the postsurgical knee rehabilitation after ACLR, bucket handle meniscus repair in a young female soccer player in 2011. The patient was treated with 12 wk of BFR and low-load lower extremity exercises. Outcome measures included thigh girth (measured every 3 wk) the Lower Extremity Functional Scale (LEFS) and the Knee Injury and Osteoarthritis Outcome Score (KOOS) physical function surveys. This is the first study to implement physical function scores in postoperative patients undergoing BFR rehabilitation. The study highlights maintenance of muscle mass at 12 wk with BFR therapy and similar LEFS and KOOS scores when compared to preoperative measurements. Unfortunately, study design does not allow for conclusions on efficacy and no comparisons can be drawn.

In 2016, Iversen et al. (51) in refutation to Takarada et al. (19) reporting a 50% reduction in disuse atrophy following ACLR published their own experience with BFR after ACLR. Twenty-four patients were included in a randomized controlled trial. With the exception of lower cuff pressures, the study protocol for BFR was identical to Takarada et al., utilizing 5 × 5 min occlusion periods with 3-min reperfusion periods between sets. However, the studies differed in that Iversen et al. included 20 low-load quadriceps exercises. The primary outcome measure was quadriceps CSA as measured by MRI. In contrast to Takarada et al., Iversen et al., reported no significant difference in quadriceps atrophy between the BFR and non-BFR groups. The differing results in these two studies highlight the potential effects of complete vascular occlusion (19) versus partial occlusion (51) in the use of BFR. Additionally, the results of Iversen are surprising in the setting of numerous previous studies showing muscle hypertrophy and adaptations to BFR combined with low-resistance exercise (15,20–30).

In 2017, Tennent et al. (53) published a randomized controlled pilot study investigating the effects of BFR training after nonreconstructive knee arthroscopy. Seventeen patients were included (age, 18–65 years) and followed for 6 wk of postoperative rehabilitation in both BFR and non-BFR groups. Rehabilitation protocols were identical with the exception that the BFR group underwent three additional exercises at 30% of the patient’s 1RM. Maximal tourniquet inflation time was 5 min at 80% limb occlusion pressure (LOP). Outcome measures included thigh girth (tape measure), strength, physical performance exercises (i.e., sit to stand, timed up and go, etc.) as well as physical function testing via KOOS and the Veterans RAND 12-Item Healthy Survey (VR-12). The results showed a two-fold greater improvement in knee extension/flexion strength and a significant increase in muscle girth, and improvements in all physical outcome measures in the BFR group compared to the control group.

Unfortunately, there is a paucity of data on the safety of postoperative BFR rehabilitation. However, none of the five available studies reported any complications related to BFR use and there are no case reports of injury related to BFR use in a postoperative rehabilitation patient. There also may be other unexplored issues that could affect the feasibility of postoperative BFR use such as discomfort related to the device, cost, patient compliance and a general lack of knowledge in the community regarding the practice.

Authors Current Protocol

The current authors have experience and expertise using the KAATSU Nano system (KAATSU Global, Inc) in collegiate and international level wrestlers. In general, therapy is performed in accordance with KAATSU preestablished protocols and user manual (50,52,54). Inflatable KAATSU Air Bands (KAATSU Global, Inc) are strapped to the users extremity, to regulate and monitor inflation pressure to achieve moderate blood flow during low-intensity exercise. The system collects data including pressure, duration of activity, capillary refill time, and type of exercise with a maximum time of use being 15 min for arms and 20 min for legs. In brief, the KAATSU Nano is a portable touch-screen device intended for certified KAATSU specialists or trainers working with athletes at a training facility. The KAATSU Nano regulates compressed air targeting two pressure measurements; the base standard KAATSU units (base SKU) and the optimal standard KAATSU units (optimal SKU). Base SKU represent the initial tightness of the bands when manually placed and recommended 40 to 50 SKU for competitive athletes. Optimal SKU are defined as the resulting tightness secondary to band inflation and varies greatly depending on the individual and the associated exercise. The correct optimal SKU is “not high enough to occlude blood flow, but high enough to achieve a profound disturbance of homeostasis in the exercising muscle over the course of the exercises” (54). Essentially, optimal SKU can be guided by constant evaluation of skin coloration, pulsation and muscle contraction failure within three sets of a given exercise (three-point exercise). Skin coloration should remain pink or beefy red with present capillary refill at all times. Pulsation should always be present with the user noting pulsations under the inflated band.

In our training facility, each individual is fitted for the appropriate band and base and optimal SKU are recorded. Once optimal SKU is determined, exercise commences typically using three to four exercises for three sets of 20 to 30 repetitions. Exercises are repeated two to three times per week. Exercises include seated toe curls, seated toe raises, standing hamstring curls, quarter squats, seated knee extension, body weight squats, single leg press, split squat ball toss, wrestling-specific stance and motion (3 × 30 s). It is important to note that recommended KAATSU protocols differ widely for the intended individual with various protocols targeting the injured patient, aging patient, weekend warrior, and even the elite athlete. We suggest following manufacturer's protocols for all BFR systems to prevent injury or complication.

Conclusions

We have reviewed the entire English-language literature on BFR available on PubMed with the general consensus being that BFR and low-load resistance training produces muscle hypertrophy and reduces disuse atrophy. This makes BFR an attractive treatment regimen for many musculoskeletal injuries. Patients with musculoskeletal injuries, particularly postoperative patients, often cannot tolerate, or are restricted by the physician from, the traditional high load exercises that combat muscle loss. Furthermore, it is well published and accepted that muscle atrophy and strength reduction leads to pain, disability and poor functional outcomes (55–57). The difficulty is that restoring skeletal mass and strength is not easily achieved clinically — requiring heavy-load, high intensity and sustained long-term regimens. Moreover, these regimens have been associated with orthopedic complications involving cardiovascular and skeletal damage (58,59). Miyachi et al. (58) linked high intensity resistance training with significant reductions in central artery compliance. Thus, these exercises, despite being highly unachievable in the postoperative patient, may additionally pose harmful implications — especially in patients with preexisting cardiovascular disease.

Overall, given the implications of muscle atrophy and weakness in the setting of a postoperative patient restricted from traditional exercise, BFR combined with low-load resistance training is very attractive in potentially preventing or reducing disuse or postoperative muscle atrophy. However, despite the studies reviewed in this article, there remains a dearth of information on its application, effectiveness, and utilization in the postoperative patient. Specifically, there is no agreed upon method of BFR in terms of tourniquet use, pressure, duration, interval, or what specific exercises to be utilized. Most importantly, however, we do not know what impact BFR and muscular hypertrophy and/or adaptations have on physical function or patient outcomes. BFR is a promising and theoretically attractive tool to assist in the rehabilitation of the postoperative patient and there have been no reports of safety concerns or adverse events in this population; however, due to the paucity of data and lack of agreement on treatment protocols, we do not feel prepared to recommend its routine use in musculoskeletal rehabilitation.

ARP receives textbook royalties from McGraw-Hill. No conflict of interest for BGW or JJD.

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