The Effectiveness of Blood Flow Restriction Training on Upper Extremity Muscle Strength: A Systematic Review

Abstract

Objective This systematic review aims to investigate the effect of blood flow restriction training (BFRT) on upper extremity muscle strength in pathological conditions of the upper extremity musculoskeletal system or in healthy individuals.

Materials and Methods This study was conducted in accordance with the PRISMA guideline statement. The randomized controlled studies which published from January 2000 to May 2022 were searched in the PubMed, Web of Science, MEDLINE, Scopus, and Cochrane Library databases. Inclusion criteria were healthy clinical population or musculoskeletal pathology related to the upper extremity, participants aged 18 and above, application of blood flow restriction to the arm, a randomized controlled study design, and publication in English. Additionally, the presentation of upper extremity muscle strength as an outcome measurement was required. The quality of the studies was evaluated using The Physiotherapy Evidence Database (PEDro) scale. Articles that were non-randomized, inaccessible in full text, and scored 4 or below on the PEDro scale were excluded.

Results Five studies were included with 219 participants. The included studies had PEDro scores ranging from 5 to 8, with an average score of 6.4. This review demonstrated a positive or neutral effect of BFRT on grip strength and shoulder strength.

Conclusion Although some studies have reported positive effects of BFRT on upper extremity muscle strength, there is no conclusive evidence regarding the protocol to be used for increasing upper extremity muscle strength.

Zusammenfassung

Ziel Diese systematische Übersichtsarbeit zielt darauf ab, die Auswirkungen des Blutflussbeschränkungstrainings (BFRT) auf die Muskelkraft der oberen Extremitäten in pathologischen Zuständen des muskuloskelettalen Systems der oberen Extremität oder bei gesunden Personen zu untersuchen.

Material und Methoden Diese Studie wurde gemäß der PRISMA-Leitlinie durchgeführt. Es wurden randomisierte kontrollierte Studien gesucht, die von Januar 2000 bis Mai 2022 in den Datenbanken PubMed, Web of Science, MEDLINE, Scopus und der Cochrane Library veröffentlicht wurden. Die Einschlusskriterien umfassten eine gesunde klinische Population oder muskuloskeletale Pathologien im Zusammenhang mit der oberen Extremität, Teilnehmer im Alter von 18 Jahren und älter, Anwendung von Blutflussbeschränkung am Arm, ein randomisiertes kontrolliertes Studiendesign und die Veröffentlichung in englischer Sprache. Darüber hinaus musste die Messung der Muskelkraft der oberen Extremität als Ergebnismessung präsentiert werden. Die Qualität der Studien wurde mit der Physiotherapy Evidence Database (PEDro) Skala bewertet. Artikel, die nicht randomisiert waren, nicht im Volltext zugänglich waren und einen PEDro-Score von 4 oder weniger hatten, wurden ausgeschlossen.

Ergebnisse Fünf Studien mit 219 Teilnehmern wurden eingeschlossen. Die eingeschlossenen Studien hatten PEDro-Werte zwischen 5 und 8, mit einem Durchschnittswert von 6,4. Diese Übersichtsarbeit zeigte eine positive oder neutrale Wirkung von BFRT auf die Griffkraft und die Schulterkraft.

Fazit Obwohl einige Studien positive Effekte von BFRT auf die Muskelkraft der oberen Extremitäten berichtet haben, gibt es keine abschließenden Beweise bezüglich des Protokolls, das zur Steigerung der Muskelkraft der oberen Extremitäten verwendet werden sollte.

Keywords

blood flow restriction - occlusion training - upper extremity - blood flow restriction training

Schlüsselwörter

Training zur Einschränkung des Blutflusses - Einschränkung des Blutflusses - Okklusionstraining - obere Extremität

Introduction

In recent years, blood flow restriction training (BFRT) has gained popularity among scientific research. BFRT is the partial restriction of arterial flow by applying pneumatic cuffs to the proximal portion of the extremity and complete restriction of venous outflow [1] [2]. According to the original perspective, exercise training with a load exceeding 70% of 1RM (repetition-maximum) can induce muscle hypertrophy [3]. Previous studies have demonstrated significant gains in muscle strength and hypertrophy even with resistance training at 30% of 1RM when combined with blood flow restriction (BFR) [4] [5]. An advantage of BFR is its ability to yield gains comparable to or greater than using a load of 80% of 1RM when only 30% of 1RM load is employed [6]. The use of lower loads reduces stress on the joints and preserves structure. It is a method that can be preferred in individuals experiencing difficulty in performing high-load training due to musculoskeletal disorders [7].

It has been demonstrated that the hypertrophic response is similar to that attained with high-load resistance exercise [8]. Furthermore, BFRT has been proven to be a reliable and effective technique for increasing muscle mass and strength. Various systematic reviews have indicated that BFR can be used for the rehabilitation of individuals in pathological conditions [9] [10]. While studies have predominantly focused on the use of BFR in lower extremity training [8], the effectiveness of its application in upper extremity exercises remains unknown. For all these reasons, the purpose of this review is to analyze how BFRT can be most effectively utilized to enhance upper extremity muscle strength.

Methods

The protocol for this systematic review, is registered in PROSPERO which is an international database of prospective registered systematic reviews (Registration Number: CRD42022328559). This systematic review was developed by using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines [11].

PubMed, Web of Science, MEDLINE, Scopus, and Cochrane Library databases were searched from January 2000 to May 2022. Only articles published in English were considered for evaluation. The keywords used in the research are ‘Blood flow restriction,’ ‘blood flow restriction training,’ ‘blood flow restriction therapy,’ ‘occlusion training,’ and ‘KAATSU training.’ The search steps for the databases are explained in the flowchart. Articles that were not randomized studies or could not be accessed in full text (despite attempts to contact the authors via email) were excluded. Additionally, articles with a PEDro score of 4 or below were not included. Inclusion criteria comprised a clinical population with either healthy individuals or those with musculoskeletal pathology of the upper extremity, participants aged 18 years or older, a study design with a randomized controlled trial, the application of BFR to the arm, and a study assessing upper extremity muscle strength before and after intervention. Evaluated outcomes include isokinetic and/or isometric force data for upper extremity muscle strength. Data search, collection, and analysis of the studies were independently conducted by two reviewers (EA and EAY). Discrepancies were discussed with a third reviewer (ARO). Reviewers initially read titles and abstracts of the studies without knowledge of each other's assessments based on eligibility criteria. Full texts of the selected studies were accessed and thoroughly analyzed. To evaluate the methodological quality of the studies, The Physiotherapy Evidence Database scale (PEDro scale) was used [12], which includes of 11 items, with the first question not contributing to the total score, resulting in a maximum score of 10 points [13] [14]. All selected articles were reviewed by two reviewers (EA and EAY), and any disagreements were resolved by consulting a third reviewer (ARO).

Results

Twenty-four randomized controlled studies which are suitable for qualitative results were shown in the flowchart ([Fig. 1]). Twenty-four studies were included in the quantitative synthesis and 19 studies were excluded as their PEDro scores were below 5. The PEDro scores of the included studies ranged from 5 to 8 (out of a maximum of 10), with an average score of 6.4 ([Table 1]). The characteristics of the studies are presented in [Table 2]. The studies include 219 participants. One of the studies focused on patients with hand osteoarthritis [15], while four studies were conducted on healthy participants [16] [17] [18] [19]. Hand grip strength was evaluated in two studies, one using the Jamar hydraulic dynamometer [16] and the other using a digital dynamometer [15]. Shoulder muscle strength was evaluated in three studies: one utilized isokinetic testing and a dynamometer for shoulder internal and external rotators [17], second one using manual muscle testing for the supraspinatus and external rotators [18], and the third using a hand-held dynamometer for shoulder abductors, internal and external rotators [19].

Fig. 1 Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flowchart diagram of the search process.

Table 1 PEDro score for included studies.

	Q-1	Q-2	Q-3	Q-4	Q-5	Q-6	Q-7	Q-8	Q-9	Q-10	Q-11	Score
Florianovicz et al., 2019	(+)	(+)	(+)	(+)	(–)	(–)	(–)	(+)	(+)	(+)	(+)	7
Bowman et al., 2020	(+)	(+)	(+)	(+)	(–)	(–)	(+)	(+)	(–)	(+)	(+)	7
Brumitt et al., 2020	(+)	(+)	(–)	(–)	(–)	(–)	(+)	(+)	(–)	(+)	(+)	5
Magni et al., 2021	(+)	(+)	(+)	(+)	(–)	(–)	(+)	(+)	(+)	(+)	(+)	8
Lambert et al.,2021	(+)	(+)	(–)	(–)	(–)	(–)	(+)	(+)	(–)	(+)	(+)	5

Q: Question; (+): Yes; (–): No

Table 2 Characteristics of included studies.

Studies	Population Characteristics	Strength Measurement (method/muscle)	Exercise	Protocol	Duration/Frequency	Exercise Load	Conclusion
Florianovicz et al. PEDro score: 7	Healthy women n=58 EG-1: (n=15), 22± (1.19) years EG-2: (n=15), 21±(1.24) years EG-3: (n=14), 21±(2.2) years CG: (n=14), 21±(2.1) years	Jamar dynamometer/ Handgrip strength MM-50 load cell/ wrist extensor muscle EMG (radial carpal extensor muscle)	Wrist extensor muscle strengthening	10 set x6	8 intervention 2 days/wk	BFR 1 RM %40	Significant increase in wrist extensor strength in the BFR group compared to the control group (p=0.004)
Bowman et al. PEDro score: 7	Healthy subjects n=24 EG: (n=14), 26.2±3.4 years CG: (n=10), no difference in age	İsokinetic test/ shoulder internal and external rotation Dynamometry /shoulder-elbow and grip strength	Shoulder external rotation – internal rotation Biceps curl -Triceps extension  prone horizontal shoulder abduction	BFR 1-RM %30	6 wk 2 days/wk	BFR pressure %60	Proximal and distal muscle strength and hypertrophy increased more in BFR group than in control group
						BFR: 30–15– 15–15
Brumit et al. PEDro score: 5	Healthy subjects n=46 25.0±2.2 years	Manuel muscle test/ Supraspinatus and Shoulder external rotators	Side-lying external rotation exercise	BFR+ exercise:1RM %30 Only exercise: :1RM %30 BFR pressure %50	8 wk 2 days/wk	BFR: 30–15– 15–15	No difference in strength in supraspinatus and external rotator muscles between the groups
Magni et al. PEDro score: 8	Hand osteoarthritis n=59 EG-1: (n=19), 67.9(8.6) years EG-2: (n=20), 72.7(9) years CG: (n=20), 75.6(12) years	Digital Dynamometer/ Handgrip strength	Grip, pinch, and thumb extension and abduction strengthening exercises.	BFR+advice 1-RM %30-40 HIT+advice	6 wk 3 days/wk	BFR: 30–15– 15–15	No improvement in grip strength and function
				1-RM %60-70		HIT: 4X10
				Just Advice (control)
Lambert et al. PEDro score: 5	Healthy adults n=32 EG: (n=16), 27.6±4.3 years CG (n=16), 25.8±4.1 years	Hand-held dynamometer /shoulder abduction, external and internal rotation	Cable ER at 0◦ cable IR at 0◦ dumbbell scaption, and side-lying dumbbell ER at 0◦	30/15/15/15 repetition (total 75 ) 20% of maximal strength assessed during the prior isometric testing BFR pressure %50	8wk 2 days/wk	resistance was increased by 1 lb (~0.45 kg) for individual exercises	Greater increases in arm lean mass and isometric IR strength in BFR group
BFR: blood flow restriction; CG: control group; EG: experimental group; ER: external rotation, HIT: high intensity training; IR: internal rotation; RM: repetition maximum.

Discussion

The limited published results indicate that BFRT may be an effective and safe method for increasing upper extremity strength in healthy individuals. No complications related to BFRT have been demonstrated in the existing studies. Five randomized controlled studies were included in the systematic review. The aim of the current systematic review is to evaluate the effects of BFRT on muscle strength in the upper extremities. Comparing results is challenging due to the lack of standardized exercise protocols with variations in exercise duration, frequency, and intensity across studies. We maintain the viewpoint that standardization of cuff pressure and parameters related to the exercise used in protocols for upper extremity BFRT is necessary. In the examined five studies, BFR was successful in improving muscle strength without causing pain, and this strength was equivalent to high-intensity resistance training. Our review demonstrated that BFRT led to a strength increase in upper extremities similar to the control group but did not show a significant difference between groups.

In systematic reviews conducted on healthy individuals, variations in cuff pressure, exercise durations, and dosages have been reported. The authors noted that a standardized cuff pressure is not suitable and emphasized the importance of personalized cuff pressure, along with the development of a model ensuring uniform occlusion for all individuals. Upon examining the four studies in our systematic review, cuff pressure was gradually increased in sessions to the extent tolerated by the participants. In terms of the BFR protocol, three studies employed the 30-15-15-15 protocol. The protocol involves the first set of 30 repetitions followed by a 30-second rest, the second set of 15 repetitions followed by a 30-second rest, the third set of 15 repetitions followed by a 30-second rest, and the fourth set of 15 repetitions.

Numerous studies were included to examine the effects of BFRT on the upper and/or lower extremities in healthy individuals in the systematic review conducted by Slysz et al [20]. In their research, which suggests the effectiveness of combining BFR with dynamic exercise training in increasing both muscle strength and size, three out of 19 studies that measured increases in muscle strength when exercise was combined with BFR focused on restriction applied to the upper extremity. Despite differences in study designs, these studies reported that low-intensity resistance training with BFR was effective on muscle strength. The results of the studies in this research indicate that BFRT could be used when traditional high-load training is inappropriate or inaccessible. These results also support our findings that progress in upper extremity muscle strength can be achieved without any reported complications. Our review revealed that a minimum of 6 weeks is necessary to achieve gains related to strength. Even though there was no standard BFR protocol, similar BFR protocols were used in the three analyzed studies and demonstrating a positive impact on muscle strength.

It has been demonstrated that BFRT provides significant benefits in muscle hypertrophy in both healthy individuals and elite athletes [10]. Determining the appropriate cuff pressure, training duration, and dosage for upper extremity strengthening muscle rehabilitation, and establishing whether an equivalent protocol to that used for healthy individuals is necessary, requires further investigation. The primary mechanisms responsible for these findings remain uncertain. With decreased blood flow through BFRT, metabolic stress levels increase, there is an augmentation in fast-twitch muscle fiber recruitment, cellular swelling is stimulated, systemic hormones are elevated, and an ischemic/hypoxic environment that enhances the production of reactive oxygen species is created [21] [22]. The review of Hughes et al. includes 20 studies regarding the use of BFR on the upper and/or lower extremities in musculoskeletal rehabilitation. Four of these studies examine resistance training combined with BFR applied to the upper extremities. Although there is no standard protocol, no side effects have been reported [21]. Similarly, in our study, no complications were reported. These results suggest that BFRexercise training applied to the upper extremities in healthy individuals may be an alternative method to high-intensity exercise training.

Individuals with hand osteoarthritis can benefit from strength trainings. In the studies conducted by Magni and colleagues [15], the feasibility of two types of strength trainings in individuals with symptomatic hand osteoarthritis was compared. According to the recommendations of the American College of Sports Medicine, high-intensity exercises are frequently suggested for hand osteoarthritis [23]. The study compared high-intensity exercise with BFRexercise according to this recommendation. The results of the study demonstrated that both strength training applications were feasible, safe, and acceptable. It was reported that the majority of participants completed the treatment, and the number of pain feedbacks was low for both exercise procedures. Additionally, no improvement in function and perception was observed in the study. The similarity of the training programs highlights the need for larger randomized controlled trials.

Conclusion

This systematic review included five studies related to BFRT and its effects on upper extremity muscle strength. While BFRT has become a popular method particularly in lower extremity muscle strengthening programs in recent years, it has also started to find its place in upper extremity programs. It is observed that there is a limited number of studies addressing the BFR to the upper extremities when reviewing literature on the effectiveness of BFRT on strength. Even though studies have reported the efficacy of low-intensity resistance training with BFR on muscle strength, due to the lack of uniform study protocols, there is no sufficient evidence regarding the most effective BFR protocol for increasing upper extremity muscle strength. There is also no reported side effect associated with its use in the upper extremity. However, this review has several limitations. Firstly, the limited number of participants reached due to the inadequacy of randomized controlled trials. Secondly, only English articles were included. Thirdly, there were variations in the characteristics of participants and sample sizes. Authors planning future studies should aim to address these limitations by increasing sample sizes, employing appropriate study designs, and providing clear and statistical analysis results to enhance the quality of the studies.

Notice

This article was changed according to the following Erratum on April 24th 2024.

Erratum

In the above-mentioned article, the institution affiliation for Ecenur Atli has been corrected. Correct is that Ecenur Atli belongs to this affiliation: 1 Graduate Education Institute, Physiotherapy and Rehabilitation, Biruni University, Istanbul, Turkey.

Conflict of Interest

The authors declare that they have no conflict of interest.

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Publication History

Received: 11 September 2023

Accepted after revision: 15 March 2024

Article published online:
18 April 2024