The efficacy of blood flow restricted exercise: A systematic review & amp; meta-analysis. J Sci Med Sport. 2016;19:669-675. [PMID: 26463594 DOI: 10.1016/j.jsams.2015.09.005]

Exercise with blood flow restriction among adults undergoing total knee arthroplasty: A scoping review

BACKGROUND

Quadriceps strength is relevant for recovering functional capacity in total knee arthroplasty (TKA). This requires strength exercises with high loads, which is difficult to perform after TKA. Rehabilitation with blood flow restriction (BFR) produces gains in strength and muscle mass, avoiding the use of heavy loads.

OBJECTIVE

To identify exercise prescription parameters and the effect of BFR training on muscle mass, muscle strength, and functional capacity of patients with TKA.

METHODS

Following the PRISMA-ScR methodology, a systematic search was carried out in the following databases: Pubmed, Virtual Health Library, Scopus, and Web of Science. The execution of exercises with BFR during TKA prehabilitation and rehabilitation stages were considered. Two authors independently assessed articles for eligibility, and a third author resolved conflicts.

RESULTS

5 articles were selected. During the prehabilitation stage, increases in strength, muscle mass, and functionality occurred. Muscle strength increased in the rehabilitation stage. Studies with a control group did not detect significant differences. Various protocols were applied regarding the prescription, dosage, and implementation of the exercise programs.

CONCLUSION

Strength, muscle size, and physical function increase in people with TKA during the prehabilitation and rehabilitation stages. The analysis carried out indicates a wide methodological variety, lack of standardization, and gaps in BFR protocol application.

The effects of blood flow restriction combined with low-intensity resistance training on muscle strength and pain during postoperative recovery in patients with knee injuries: a meta-analysis

To investigate the effects of low-load blood flow restriction training (LL-BFRT) on muscle strength and pain during postoperative rehabilitation in patients with knee injuries. A systematic review and meta-analysis was conducted in accordance with PRISMA guidelines. Comprehensive searches through PubMed, EBSCO, Cochrane, Web of Science, and Embase yielded 1049 articles, of which 13 studies met the inclusion criteria. Quantitative analyses were performed using Review Manager 5.3 and Stata. LL-BFRT showed a significant positive effect on muscle strength, with a standardized mean difference (SMD) of 0.70 (p < 0.00001, 95%CI: 0.49, 0.92, I2 = 42%, p = 0.07). In terms of pain reduction, LL-BFRT significantly lowered the outcome of visual analog scale (VAS), with an SMD of -0.60 (p < 0.00001, 95% CI: -0.85, -0.36, I2 = 0%, p = 0.44). LL-BFRT effectively improves muscle strength and reduces pain in patients recovering from knee injuries postoperatively. It presents an alternative rehabilitation method for patients who are unable to perform high-intensity resistance training.

Efficacy and acceptability of different blood flow restriction training interventions during the rehabilitation of military personnel with lower limb musculoskeletal injuries: protocol for a two-phase randomised controlled trial

BACKGROUND

Musculoskeletal injury (MSKI) is the leading cause of medical downgrading and discharge within the UK military, with lower limb MSKI having the greatest incidence, negatively impacting operational readiness. Pain is a primary limiting factor to rehabilitation progress following MSKI. Heavy-load resistance training (RT; ie, loads >70% 1-repetition maximum) is traditionally used but may be contraindicated due to pain, potentially prolonging recovery and leading to failure of essential physical employment standards for UK military personnel. Low-load RT with blood flow restriction (BFR) can promote favourable morphological and physiological adaption, as well as elicit hypoalgesia in healthy and clinical populations (eg, post-operative), and has proven a viable option in military rehabilitation settings. The acceptability and tolerance of higher relative BFR pressures in persistent pain populations are unknown due to the complexity of presentation and the perception of discomfort experienced during BFR exercise. Greater relative pressures (ie, 80% limb occlusion pressure (LOP)) elicit a greater hypoalgesic response in pain-free individuals, but greater perceived discomfort which may not be tolerated in persistent pain populations. However, lower relative pressure (ie, 40% LOP) has elicited hypoalgesia in pain-free individuals, which therefore may be more clinically acceptable and tolerated in persistent pain populations. The primary aim of both randomised controlled trials (RCT) is to investigate the efficacy and acceptability of using high-frequency, low-load BFR-RT in UK military personnel with lower limb MSKI where persistent pain is the primary limiting factor for progression.

METHODOLOGY

The presented protocol is a two-phase RCT based within a military rehabilitation setting. Phase One is a 1-week RCT to determine the most efficacious and acceptable BFR-RT protocol (7× BFR-RT sessions over 5 days at 40% or 80% LOP; n=28). Phase Two is a 3-week RCT comparing the most clinically acceptable BFR pressure, determined by Phase One (21× BFR-RT sessions over 15 days; n=26) to usual care within UK Defence Rehabilitation residential rehabilitation practices. Outcomes will be recorded at baseline, daily and following completion of the intervention. The primary outcome will be the brief pain inventory. Secondary outcomes include blood biomarkers for inflammation and pain (Phase Two only), injury-specific outcome measures, lower extremity function scale, objective measures of muscle strength and neuromuscular performance, and pressure pain threshold testing.

ETHICS AND DISSEMINATION

The study is approved by the Ministry of Defence Research Ethics Committee (2318/MODREC/24) and Northumbria University. All study findings will be published in scientific peer-reviewed journals and presented at relevant scientific conferences.

TRIAL REGISTRATION NUMBER

Registered with Clinical Trials. The registration numbers are as follows: NCT06621914 (Phase One) and NCT06621953 (Phase Two).

The impact of blood flow restriction training on tendon adaptation and tendon rehabilitation - a scoping review

BACKGROUND

Tendon injuries are common in athletes and in the general population and require extensive rehabilitation. Current conservative treatment often includes different high-load resistance training (HLRT) modalities. However, certain populations may not tolerate HLRT well. Blood flow restriction training (BFRT) incorporates low load while achieving hypertrophy and strength adaptations comparable to HLRT. However, the effects of BFRT on healthy and pathological tendons are unknown. The aims of this scoping review were therefore to summarize the reported impact of BRFT: (1) on tendon adaptation in healthy individuals, and (2) in tendon rehabilitation after injury.

METHODS

A scoping review based on PRISMA guidelines was performed. A systematic literature search in the electronic databases PubMed, SPORTDiscus and CINAHL was performed in May 2024. This review includes peer-reviewed articles investigating the effects of BFRT on healthy tendons and in tendon rehabilitation. Methodological quality was assessed using the Downs and Black scale and JBI Critical Appraisal Checklist.

RESULTS

19 studies with varied design, population, investigated tendon, intervention design and outcome measures were eligible. Ten studies were randomized controlled trials (RCT), one study was a clinical controlled trial, three studies were feasibility studies and five were case reports. The reviewed studies included 351 healthy subjects and 122 individuals with tendon-related disorders (101 subjects with tendinopathy and 21 subjects with tendon ruptures). Tendons investigated were Achilles (n = 6), patellar (n = 6), hamstring (n = 1), gluteal (n = 1), biceps brachii distal (n = 1), tendons of the rotator cuff (n = 2) and lateral elbow extensors (n = 2). In the nine studies on healthy individuals, the effects of BFRT showed contradictory results regarding tendon-related outcomes. However, changes in outcome measures did not differ significantly from HLRT conditions or low-load resistance training (LLRT) conditions. The studies on tendon rehabilitation also showed contradictory results regarding tendon-related outcomes, although several studies do report decreased pain, increased strength, enhanced performance and improved self-reported diagnosis-specific function.

CONCLUSIONS

The present scoping review shows contradictory results regarding tendon-related outcomes although studies point to increasing tendon function after rehabilitation. BFRT may be a viable option to incorporate into training regimes aimed at inducing tendon adaptation. Further in-depth research is warranted.

CLINICAL TRIAL NUMBER

This is a review and therefore is Clinical trial number: Not applicable. However, the review has been preregistered at www.osf.io (DOI https://doi.org/10.17605/OSF.IO/PYV43 ) stated in the method section.

Exercise-induced hypoalgesia following blood flow restricted exercise

OBJECTIVES

Assess the repeatability of exercise-induced hypoalgesia (EIH) following low-load resistance exercise with blood flow restriction (LL + BFR) and the magnitude of EIH following LL + BFR, high-load resistance exercise, and a control intervention 1-h after exercise.

DESIGN

Crossover design.

SETTING

University laboratory.

PARTICIPANTS

15 females, 15 males.

MAIN OUTCOME MEASURES

Pain pressure threshold and tolerance of the rectus femoris, gastrocnemius, and biceps brachii pre-exercise and 0-, 15-, 30-, 45-, and 60-min post-exercise.

RESULTS

There was no significant (p = 0.211-0.741) difference in pain pressure threshold or tolerance between LL + BFR1 and LL + BFR2 suggesting that EIH following LL + BFR is repeatable. LL + BFR elicited a significant (p = 0.001-0.043) increase in local pain pressure threshold (1.57 ± 1.21-0.98 ± 1.48 Δkgf) and tolerance (1.98 ± 2.65-0.83 ± 2.15 Δkgf) up to 1-h post-exercise. High-load resistance exercise elicited a significant (p = 0.003-0.034) increase in pain pressure threshold 0-min post-exercise (1.69 ± 1.74 Δkgf) and tolerance 0- and 15-min post-exercise (2.31 ± 2.44 Δkgf; 0.56 ± 1.83 Δkgf, respectively) then returned to pre-exercise levels. LL + BFR elicited a significant (p = 0.025-0.046) increase in systemic pain pressure tolerance (0.77 ± 0.88 Δkgf) of the gastrocnemius as well as pain pressure threshold (0.53 ± 0.54 Δkgf) and tolerance (0.49 ± 1.02 Δkgf) of the biceps brachii, when collapsed across Time.

CONCLUSIONS

LL + BFR may be a repeatable, effective pain management intervention that can produce prolonged EIH.

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.

Acute transcutaneous CO2 exposure: A feasibility study for the future investigation of CO2-specific exercise adaptations

Blood flow restricted (BFR) exercise induces musculoskeletal adaptations at reduced exercise loads. The role of hypercapnia during BFR remains unclear, due to difficulties in isolating this factor in vivo. We evaluated a hypercapnic model designed to raise CO2 levels similar to low-intensity exercise, while minimizing other exercise-induced effects (e.g. hypoxia, lactate accumulation). In a crossover design, 18 participants were administered pure CO₂ (EXP) or room air (CON) transcutaneously from the neck down for 90 min. Ventilatory and blood markers (V̇CO2, ETCO2, V̇E, pH, and PCO2) were measured throughout. The area under the curve of ETCO2 was higher during EXP compared to CON (75.5 ± 83.7 vs. 32.8 ± 57.5 a.u., p = 0.05), confirming successful CO2 administration. However, there was no significant effect on PCO2 (p = 0.09), despite a trend toward reduced pH (p = 0.059). CONCLUSION: While transcutaneous CO2 absorption induced a physiological response, the magnitude was small, and this model shows limited ecological validity to simulate exercise-like conditions.

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

PURPOSE

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.

METHODS

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.

RESULTS

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%).

CONCLUSIONS

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 OF EVIDENCE

Level II, systematic review and meta-analysis of Level I and II studies.

Effect of blood-flow restricted vs heavy-load resistance training on strength, power, and speed for healthy volunteers: a systematic review and meta-analysis

Background

Low-load blood flow restriction (LL-BFR) training has been shown to enhance muscle strength, power, and speed, but its effectiveness compared to traditional high-load resistance (HLR) training remains unclear. This meta-analysis aimed to compare the effects of LL-BFR and HLR training on muscle strength, power, and speed.

Methodology

Studies were identified by searching the SCOPUS, SPORTDiscus, PubMed, Web of Science, and CNKI databases up to May 13, 2024, using the following inclusion criteria: (a) healthy population; (b) comparison of LL-BFR vs HLR training; (c) pre- and post-training assessment of muscle strength (dynamic, isometric, and isokinetic), muscle power, jump, or speed performance; (d) PEDro scale score ≥4. The methodological quality of the included studies was assessed using the PEDro tool and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach, with meta-analyses conducted using the R program.

Results

A total of 41 studies, involving 853 subjects, were included in the meta-analysis. Based on the PEDro scores and GRADE assessment, the overall quality of the included studies was assessed as moderate. LL-BFR training showed a slightly smaller effect on maximal strength compared to HLR training (ES = -0.19, 95% CI [-0.31 to -0.06], p < 0.01). There were no significant differences between LL-BFR and HLR training for muscle power (ES = -0.04, 95% CI [-0.33 to 0.24], p > 0.05), jump performance (ES = -0.08, 95% CI [-0.30 to 0.15], p > 0.05), and speed (ES = -0.28, 95% CI [-0.71 to 0.15], p > 0.05). Additionally, individual characteristics (i.e., age, gender, and training status) and training parameters (i.e., training duration, frequency, cuff pressure, and cuff width) did not significantly moderate the training effect.

Conclusions

LL-BFR training showed slightly less improvement in maximal strength compared to HLR training but demonstrated comparable effects on muscle power, jump performance, and speed in healthy individuals in healthy individuals. These findings suggest that LL-BFR may be a practical and effective alternative for individuals seeking performance improvements with lower training loads.

Blood flow restriction during high load bench press does not increase bar velocity or cause physiological changes in non-occluded agonist muscles

PURPOSE

Blood blow restriction (BFR) can increase peak velocity and power during high load resistance training. However, previous research primarily utilized high occlusion pressures (i.e., greater than 80% arterial occlusion pressure (AOP)), and rarely measured the physiological response during or after the bench press stimuli. The aim of this study was to investigate the application of 50%AOP during acute high load bench press exercise on barbell power, velocity, and the physiological responses to this stimulus.

METHODS

Resistance trained males (n = 12, 26.2 ± 6.6 yrs., 84.0 ± 10.8 kg, 176.3 ± 10.4 cm) completed a maximum strength test followed by two experimental sessions which consisted of four sets of 4 reps of the barbell bench press at 75%1RM, with or without BFR applied to both arms at 50% AOP. Significance was set to p ≤ 0.05. A series of two-way repeated measures ANOVAs with Bonferroni post hoc corrections tested for potential changes in bar velocity, power, blood lactate, and muscle thickness and activation of the anterior deltoid and pectoralis major.

RESULTS

There were no main effects for the interaction terms "Condition×Set" or "Condition×Time," nor for "Condition" for any variables (all p > 0.05). There was a "Time" effect for blood lactate (p < 0.001) with lactate increasing from pre- to postexercise, and a main effects for "Set" for mean (p = 0.016) and peak velocity (p = 0.005).

CONCLUSION

There was no difference in the change in velocity, or physiological responses during high load bench press with or without BFR at 50%AOP. While promising, use of BFR for upper body power may require pressures >50%AOP.

Comparison of Different Methods on Post-Activation Performance Enhancement: A Meta-Analysis

This meta-analysis was aimed to compare the effects of two methods on post-activation performance enhancement (PAPE). We conducted a comprehensive search of PubMed, Web of Science, Cochrane Library, and China National Knowledge Infrastructure from inception to December 2023. Two authors independently selected the included studies, extracted data, and assessed the risk of bias and certainty evidence. The primary meta-analysis compared the effects of blood flow restriction combined with resistance training (BFR-RT) and high-load resistance training (HL-RT) on the indicator jump height (JH) and power output (PO) of PAPE. The secondary meta-analyses compared within-group differences by gender and between-group differences between the optimal combined protocol of arterial occlusion pressure (AOP) combined with resistance load and the HL-RT protocol. This meta-analysis shows that both BFR-RT and HL-RT significantly improved JH (standardized mean difference (SMD)=0.39, 95% confidence interval (CI) [0.20, 0.59]) (SMD=0.34, 95% CI [0.19, 0.48]) and PO (SMD=0.42, 95% CI [0.21, 0.62]) (SMD=0.37, 95%CI [0.19, 0.54]), and there was no significant difference between them. However, subgroup analysis revealed that in terms of gender, BFR-RT was more beneficial for PAPE in females, and in terms of combined protocol, BFR-RT with 50% AOP+30% 1 repetition maximum had the greatest effect compared to HL-RT.BFR-RT can serve as an effective alternative to HL-RT for inducing PAPE.

Effects of Acute Upper and Lower Body Resistance Exercise on Cardiovascular Response in Adult Women Through Blood Flow Restriction

The purpose of this study was to compare and contrast cardiovascular responses during acute upper body resistance exercise (UBRE) and lower body resistance exercise (LBRE) and resting with or without blood flow restriction (BFR) in adult women. The subjects were 18 adult women (21.5 ± 2.0 years old) and it was a cross-over experimental design. Resistance exercise consisted of 20% 1-RM, 10 repetitions, and 4 sets. For UBRE, arm curl and bench press exercise, and LBRE squat and leg extension exercise were performed. The change in cardiovascular response during exercise and recovery with or without BFR was significantly different between UBRE (diastolic blood pressure: DBP, mean arterial pressure: MAP, total peripheral resistance: TPR) and LBRE (DBP, MAP, heart rate: HR, Cardiac output: CO) (p < .05). In non-BFR, DBP, MAP, SV, HR, CO, there was a difference in TPR (p < .05). It was concluded LBRE with BFR had a positive effect on the cardiovascular response of the cardiovascular system during exercise and recovery.

The effects of blood flow restriction combined with endurance training on athletes' aerobic capacity, lower limb muscle strength, anaerobic power and sports performance: a meta-analysis

OBJECTIVE

To evaluate the effects of blood flow restriction (BFR) combined with endurance training on aerobic capacity, lower limb muscle strength, anaerobic power, and sports performance to supply effective scientific guidance for training. Two reviewers independently screened the literature, extracted data, and assessed the risk of bias of the included studies. We searched PubMed, Medline, Cochrane, SPORTDiscus and Web of Science databases up to 28 October 2024. Two reviewers independently screened the literature, extracted data, and assessed the risk of bias of the included studies. We calculated the effect size using standardized mean difference values and the random effects model. The results showed a medium effect size on maximal oxygen uptake (V̇O2max), a large effect size on lower limb muscle strength, a small effect size on anaerobic power and sports performance. In conclusion, while BFR training during endurance training had a significant positive effect on lower limb muscle strength and moderate improvement in V̇O2max, its impact on anaerobic power and sports performance was relatively small. These findings suggest that BFR training may be effective for enhancing muscle strength and aerobic capacity, but its benefits on anaerobic power and sport-specific performance may be limited. Therefore, it is important to carefully design BFR training programs to target specific outcomes.

How can Blood Flow Restriction Exercise be Utilised for the Management of Persistent Pain Following Complex Injuries in Military Personnel? A Narrative Review

BACKGROUND

Persistent pain is a complicated phenomenon associated with a wide array of complex pathologies and conditions (e.g., complex regional pain syndrome, non-freezing cold injury), leading to extensive disability and reduced physical function. Conventional resistance training is commonly contraindicated in load compromised and/or persistent pain populations, compromising rehabilitation progression and potentially leading to extensive pharmacological intervention, invasive procedures, and reduced occupational status. The management of persistent pain and utility of adjunct therapies has become a clinical and research priority within numerous healthcare settings, including defence medical services.

MAIN BODY

Blood flow restriction (BFR) exercise has demonstrated beneficial morphological and physiological adaptions in load-compromised populations, as well as being able to elicit acute hypoalgesia. The aims of this narrative review are to: (1) explore the use of BFR exercise to elicit hypoalgesia; (2) briefly review the mechanisms of BFR-induced hypoalgesia; (3) discuss potential implications and applications of BFR during the rehabilitation of complex conditions where persistent pain is the primary limiting factor to progress, within defence rehabilitation healthcare settings. The review found BFR application is a feasible intervention across numerous load-compromised clinical populations (e.g., post-surgical, post-traumatic osteoarthritis), and there is mechanistic rationale for use in persistent pain pathologies. Utilisation may also be pleiotropic in nature by ameliorating pathological changes while also modulating pain response. Numerous application methods (e.g., with aerobic exercise, passive application, or resistance training) allow practitioners to cater for specific limitations (e.g., passive, or contralateral application with kinesiophobia) in clinical populations. Additionally, the low-mechanical load nature of BFR exercise may allow for high-frequency use within residential military rehabilitation, providing a platform for conventional resistance training thereafter.

CONCLUSION

Future research needs to examine the differences in pain modulation between persistent pain and pain-free populations with BFR application, supporting the investigation of mechanisms for BFR-induced hypoalgesia, the dose-response relationship between BFR-exercise and pain modulation, and the efficacy and effectiveness of BFR application in complex musculoskeletal and persistent pain populations.

Leg blood flow during exercise with blood flow restriction: evidence for and implications of compensatory cardiovascular mechanisms

Proximal limb cuff inflation to 40% arterial occlusion pressure (AOP) is assumed to reduce exercising leg perfusion, creating "blood flow restriction" (BFR). However, no study has validated this assumption. Eighteen healthy young participants (9 F) performed two-legged knee flexion/extension exercise at 25% WRpeak with bilateral cuffs applied to the proximal thigh at 0% AOP (CTL), 20% AOP, and 40% AOP. Leg blood flow (LBF; Doppler and echo ultrasound) and cardiac output (CO; finger photoplethysmography) were measured during rest and exercise. LBF values were doubled to account for both exercising legs. AOP (20% and 40%) reduced exercising LBF in a dose-response manner (P < 0.01). However, the magnitude of the leg blood flow restriction by 40% AOP was progressively attenuated across the exercise bout (5-15 s: 37%, 50-70 s: 20%, 240-300 s: 16%; P < 0.01) due to compensatory increases in leg vascular conductance (LVC) (P < 0.01). Between 5 and 15 s of exercise, 40% AOP significantly reduced CO compared with CTL and 20% AOP (8.0 ± 1.3 vs. 8.4 ± 1.5 L/min, P < 0.001 and 8.5 ± 1.5, P < 0.001). By 240-300 s, there were no significant differences in CO between cuff pressures (all P > 0.13). Pneumatic cuff inflation at 20% and 40% AOP reduces LBF in a dose-response manner, but this impairment was progressively attenuated across the exercise bout by an increase in LVC. Importantly, this compensatory response differed across participants, which may have implications for the degree of adaptations following BFR training. Furthermore, restoration of normal CO during BFR despite compromised limb perfusion suggests that other tissue perfusion is increased as part of the response.NEW & NOTEWORTHY It remained to be determined whether BFR set below 60% AOP impairs leg blood flow during continuous exercise. We showed that BFR at 20% and 40% AOP impairs exercising leg blood flow in a dose-response manner. However, the leg blood flow impairment was progressively attenuated across the exercise bout. Both initial compromise and partial restoration varied across participants, which may have implications for the degree of muscle adaptations following BFR training.

Effectiveness of blood flow restriction training during a taper phase in basketball players

This study investigates the effectiveness of blood flow restriction (BFR) training in maintaining athletic performance during a taper phase in basketball players. The taper phase aims to reduce external load while maintaining training intensity. Seventeen experienced basketball players were randomised into two groups: a placebo group (n = 8, 22.0 ± 2.1 years, mean ± SD) and BFR group (n = 9, 21.1 ± 1.5 years). The training schedule included strength trainings, team trainings, individual skill sessions and competitive games. During the 4-week taper period, lifting volume was reduced while either maintaining (placebo) or reducing (BFR) lifting load. The BFR group lifted with 60% arterial occlusion pressure at 25-30% of their 1RM, whereas the placebo group trained at 80% of their 1RM with BFR cuffs inflated to only 20%. Compared to the placebo group, BFR participants improved 5 m (-1.4 ± 1.5% mean ± 95% CI p = 0.03) and 10 m (-1.1 ± 0.5%, p =  <0.01) sprint performance along with barbell back squat (9.6 ± 8.0%, p = 0.013) and countermovement jump (1.1 ± 0.8%, p = 0.0035). BFR during the taper phase enabled a reduction in lifting load with no reduction in subsequent performance measures.

Limb dominance does not have a meaningful impact on arterial occlusion pressure

INTRODUCTION

Limb dominancy has been suggested, by some, to influence arterial occlusion pressure (AOP). However, we hypothesized that the differences in AOP between the dominant and nondominant legs were more likely explained by differences in cuff position.

AIMS

To determine the impact of limb dominance, composition, and cuff position on AOP in the context of error associated with measuring AOP twice on the same leg.

METHODS

Fifty-eight adults (30 males) volunteered to have AOP measured on their dominant legs with the cuff bladder covering their inner thighs and on their nondominant legs with the bladder covering their inner and outer thighs (in random order). Thigh circumference and muscle and fat thicknesses were also measured on each leg.

RESULTS

We found evidence for differences in AOP between legs [median δ of -0.222, 95% credible interval: (-0.429, -0.016)] when the cuff position was matched. The mean difference was -2.8 mmHg, and the 95% limit of agreement in a Bland-Altman plot was -24.8 to 19.0 mmHg. When plotting this alongside an error range (i.e., 95% limits of agreement) of taking the same measurement twice from our previous study (Spitz et al., 2020), 52 out of 58 measurements were within the error range. This difference was not due to the cuff position. Additionally, there was no evidence that thigh circumference or composition (muscle/fat thickness) moderated any difference between limbs.

CONCLUSION

The difference in AOP between limbs is small and is mostly indistinguishable from the difference observed from taking the measurement twice on the same limb.

Effects of different pre-exercise strategies on jumping performance in female volleyball players

BACKGROUND

The present study aimed to compare different pre-exercise strategies on jumping performance in female volleyball players.

METHODS

Fifteen healthy female volleyball players (age=18±0.6 years; training experience = 7.3±1.4 years; height = 164.8±5.4 cm; body mass = 57.2±8.1 kg) volunteered to participate in the study. Three different pre-exercise conditions (5 repetition maximum knee extension, electromyostimulation [EMS] and ischemic preconditioning [IPC]) were applied to the subjects and compared to a control condition performing a standardized warmup. Subjects performed the squat jump and 15 sec repeated countermovement jumps following a rest period. Measures associated with jumping performance were collected and compared between conditions. Rating of perceived exertion was also collected after each performance test.

RESULTS

No pre-exercise condition outperformed a standardized warm-up on inducing improvements in jumping performance and in fact, EMS and IPC conditions resulted in performance decrements compared to control (P<0.05).

CONCLUSIONS

We conclude that a standardized warm-up is enough to induce improvements in jumping performance in female volleyball players. Future research should examine alternative strategies alongside standardized warm-up to determine how best to prepare for jumping and related sport-specific tasks in female volleyball players.

Blood flow restriction-enhanced platelet-rich plasma: A pilot randomised controlled trial protocol

Purpose

To assess platelet-rich plasma (PRP) changes in platelet and leucocyte count, insulin-like growth factor 1 (IGF-1), and interleukin 6 (IL-6) concentration after bilateral low-load knee extensions under blood flow restriction (BFR).

Methods

The present randomised controlled trial protocol will include two groups: the intervention group, which will undergo bilateral knee extensions under BFR, and the control group, which will perform bilateral knee extensions without BFR. Participants will be randomly allocated in a 1:1 ratio. Twenty-two healthy individuals will be enrolled if the predefined inclusion criteria are met: (1) males, (2) ages 18-40, (3) Tegner activity level ≥5 and (4) with no musculoskeletal conditions that would interfere with exercise. Exclusion criteria include (1) individuals with systemic inflammatory diseases, (2) cardiovascular risk factors, (3) any blood dyscrasia, (4) Tegner Activity scale scores <5, (5) under nonsteroidal anti-inflammatory drugs and aspirin treatment within one week before testing or (6) that had previously performed exercises on the testing day. The participant will perform low-load bilateral knee extensions under BFR following a standard protocol of 30-15-15-15 repetitions of consecutive sets with 30-s rest intervals at 80% of limb occlusive pressure and 30% of 1-RM load. PRP platelet and leucocyte count, IGF-1 and IL-6 concentration measurements (via flow cytometry, chemiluminescence testing and immunochromatography, respectively) will be conducted before exercise and 10, 20 and 30 min after the intervention.

Results

The expected outcome is that the standard protocol of low-load bilateral knee extensions under BFR will increase the platelet and leucocyte count, IGF-1 and IL-6 in the PRP preparation.

Conclusion

The current protocol allows the study of an enhanced PRP formulation for its potential implementation in multiple sports injuries.

Blood flow restriction training with cross education for quadriceps muscle recovery after anterior cruciate ligament reconstruction: A prospective, randomized, controlled, single-blind clinical trial

PURPOSE

Recently, blood flow restriction (BFR) and cross education (CE) trainings are the options for quadriceps strength recovery after anterior cruciate ligament reconstruction (ACLR). The aim of this study was to investigate the effects of CE combined with BFR on quadriceps strength and thickness after ACLR.

METHODS

Twenty-four male patients [(Age: 24.9 ± 6.3 years, body mass index: 24 ± 2.3 kg/m2) who had undergone ACLR with hamstring autograft were included. At 4 weeks after surgery, the patients were randomly divided into two groups (Group-1: CE + BFR, n = 13, Group-2: CE, n = 11). All patients had standardized rehabilitation for their reconstructed limb until 12 weeks postsurgery, and they all received CE training for uninjured limb at isokinetic system (quadriceps eccentric contraction, 60°/s 3-set 12-rep, 2-days in a week) during 8 weeks. Group 2 performed the same CE procedure with BFR. Quadriceps isometric strength was measured using an isokinetic dynamometer, while the thickness of quadriceps (rectus femoris, vastus lateralis, vastus medialis obliquus) and cross-sectional area of rectus femoris were evaluated using ultrasound pretraining (4th-week postsurgery) and posttraining (12th-week postsurgery). Analysis of variance was used for statistical analysis.

RESULTS

Group-by-time interaction and the group main effect were not significant for any measured variables in both limbs (p > 0.05). There was a significant main effect of time observed for quadriceps strength and thickness in involved and uninvolved limbs (p < 0.001, p < 0.05, respectively). In Group 1, the limb symmetry index for quadriceps strength increased from 49.3% to 71.7%, while in Group 2, it increased from 50.9% to 75.2%.

CONCLUSION

BFR training, adapted to CE eccentric strengthening, may not be effective for quadriceps muscle strength recovery after ACLR. Further investigations with varied training protocols are needed to research the impact of BFR on CE.

LEVEL OF EVIDENCE

Level II randomized controlled trial.

Lower Extremity Blood Flow Restriction Training in Athletes Significantly Improves Strength-Related Outcomes in 58% of Studies Compared to Non-Blood Flow Restriction Control

PURPOSE

To examine the role of lower extremity blood flow restriction (BFR) in the athletic population.

METHODS

This study was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement guidelines. Searches of Level I and II studies were performed on PubMed, Embase, and Cochrane databases. Article identification was performed in August 2024. Studies related to BFR in the lower extremity in athletic populations were included. The data collected included athlete demographics; treatment groups; BFR training protocols; control training protocol; exercises performed; training duration and frequency; cuff type, size, and pressure; muscles targeted; strength improvement; endurance improvement; muscle growth; and sport-specific metrics (speed, jump height, etc.).

RESULTS

Twenty studies were identified for inclusion. Significant within-group strength increases from pre- to post-training in the BFR group were reported in 19 of 20 studies, with at least 1 strength outcome being significantly increased in the BFR group compared to the control group in 11 of 19 studies (58%). Outcomes related to muscle size were reported in 14 studies, with 10 of these studies reporting within-group increases for the BFR group in at least 1 muscle size metric. Sport-specific metrics were reported in 12 studies, and 4 studies reported on endurance outcomes and generally favored the BFR group over the control group. Five of 6 studies comparing low-load exercise with BFR to high-load exercise without BFR reported comparable outcomes between groups.

CONCLUSIONS

In this systematic review, we found that 58% of studies reporting on lower extremity BFR use in athletes observed significant strength improvements in the BFR group compared to a non-BFR group. Additionally, when comparing low-intensity exercise with BFR to high-intensity exercise without BFR, 5 of 6 studies reported either improved or comparable outcomes between the BFR and control groups. In general, exercise with and without BFR led to improvements in lower extremity strength, muscle size, endurance outcomes, and sport-specific metrics, and most of the included studies reported greater improvements within the BFR group.

LEVEL OF EVIDENCE

Level II, systematic review of Level I and II studies.

Impact of Five Weeks of Strengthening Under Blood Flow Restriction (BFR) or Supplemental Oxygen Breathing (Normobaric Hyperoxia) on the Medial Gastrocnemius

Background and Objectives: This study investigates the effects of a five-week training program on the medial gastrocnemius muscle, comparing two approaches: blood flow restriction (BFR) training and normobaric hyperoxia (oxygen supplementation). It evaluates three strengthening modalities (dynamic, isometric, and the 3/7 method) analyzing their impact on maximal voluntary contraction (MVC), muscle architecture, and perceived exertion. Methods: A total of 36 young healthy participants (21 females, 15 males) were randomized into six subgroups (n = 6 each) based on the type of contraction and oxygen condition. Training sessions (three per week) were conducted for five weeks at 30% of MVC. Measurements of MVC, muscle circumference, pennation angle, fascicle length, and perceived exertion were taken at baseline (T0), mid-protocol (T1), and post-protocol (T2). Results: All groups demonstrated significant increases in MVC after five weeks, with no notable differences between BFR and oxygen conditions. Structural changes were observed in specific subgroups: the BFR-isometric group showed increased calf circumference (p < 0.05), and the 3/7 groups exhibited significant fascicle length gains (p < 0.05). Perceived exertion was consistently higher in BFR groups compared to oxygen supplementation, particularly in dynamic exercises. Conclusions: Both BFR and oxygen supplementation are effective in enhancing strength with light loads, though they elicit different structural and perceptual responses. Oxygen supplementation may be more comfortable and less strenuous, offering a viable alternative for populations unable to tolerate BFR. Future research should focus on optimizing training parameters and exploring applications tailored to specific athletic or clinical contexts.

Altered muscle fibre activation in an antagonistic muscle pair due to perturbed afferent feedback caused by blood flow restriction

PURPOSE

This study aimed to better understand the coping strategy of the neuromuscular system under perturbed afferent feedback. To this end, the neuromechanical effects of transient blood flow restriction (BFR) compared to atmospheric pressure were investigated in an antagonistic muscle pair.

METHODS

Perceived discomfort and neuromechanical parameters (torque and high-density electromyography) were recorded during submaximal isometric ankle dorsiflexion before, during and after BFR. The tibialis anterior and gastrocnemius lateralis muscles were studied in 14 healthy young adults.

RESULTS

Discomfort increased during BFR and decreased to baseline level afterwards. The exerted torque and the co-activation index remained constant, whereas the EMG signal energy increased significantly during BFR. Coherence analysis of the delta band remained constant, whereas the alpha band shows an increase during BFR. Median frequency and muscle fibre conduction velocity showed a positive trend during the first minutes of BFR before significantly decreasing. Both parameters exceeded baseline values after cuff deflation.

CONCLUSION

Perturbed afferent feedback leads to altered neuromechanical parameters. We assume that increased central drive is required to maintain force output, resulting in changed muscle fibre activity. Glycolytic fast-switch fibres are only active for a short time due to oxygen deprivation and hyperacidity, but fatigue effects predominate in the long term.

Blood flow modulation to improve motor and neurophysiological outcomes in individuals with stroke: a scoping review

Ischemic Conditioning (IC) is a procedure involving brief periods of occlusion followed by reperfusion in stationary limbs. Blood Flow Restriction with Exercise (BFR-E) is a technique comprising blood flow restriction during aerobic or resistance exercise. Both IC and BFR-E are Blood Flow Modulation (BFM) strategies that have shown promise across various health domains and are clinically relevant for stroke rehabilitation. Despite their potential benefits, our knowledge on the application and efficacy of either intervention in stroke is limited. This scoping review aims to synthesize the existing literature on the impact of IC and BFR-E on motor and neurophysiological outcomes in individuals post-stroke. Evidence from five studies displayed enhancements in paretic leg strength, gait speed, and paretic leg fatiguability after IC. Additionally, BFR-E led to improvements in clinical performance, gait parameters, and serum lactate levels. While trends toward motor function improvement were observed post-intervention, statistically significant differences were limited. Neurophysiological changes showed inconclusive results. Our review suggests that IC and BFR-E are promising clinical approaches in stroke, however high-quality studies focusing on neurophysiological mechanisms are required to establish the efficacy and underlying mechanisms of both in stroke. Recommendations regarding future directions and clinical utility are provided.

Efficacy of Blood Flow Restriction Exercise for Improving Lower Limb Muscle Strength and Function in Chronic Spinal Cord Injury: A Randomized Controlled Trial

The objective of the present study was to evaluate the efficacy of low-load (LL) blood flow restriction exercise (BFRE) for improving lower limb muscle strength, muscle thickness and physical function in individuals with spinal cord injury (SCI). In a randomized sham-controlled trial, 21 participants (age ≥ 18 years, SCI duration ≥ 1 year, knee extensor strength grade 2-4, ASIA A-D) were randomized to either 45-min LL-BFRE (n = 11) or sham BFRE (n = 10) twice/week for 8 weeks. The exercise protocol consisted of four sets (30 × 15 × 15 × 15 repetitions) of unilateral seated leg extensions and leg curls at 30%-40% of 1RM performed with pneumatic cuffs applied proximally on the trained limb and inflated to 40% of total arterial occlusion pressure (BFRE) or non-inflated (sham exercise). Maximal voluntary isometric quadriceps and hamstring muscle strength, quadriceps muscle thickness, thigh circumference, and physical function were assessed at baseline, after 4 and 8 weeks of training and at 4-week follow-up. No significant between-group differences were found between BFRE and sham exercise in quadriceps or hamstring muscle strength, 10-m walking test, timed up & go, 6-min walking test or the spinal cord independence measure. In contrast, a significant between-group difference favoring BFRE was present for muscle thickness and thigh circumference from baseline to 4-week follow-up (0.76 cm (95% CI: 0.32; 1.20, p = 0.002) and 2.42 cm (0.05; 4.79, p = 0.05), respectively). In conclusion, there was no significant difference in the effect of LL-BFRE and sham exercise on muscle strength and physical function in individuals with SCI. However, significant increases in muscle thickness and thigh circumference were observed in favor of BFRE. Trial Registration: ClinicalTrials.gov identifier: NCT03690700.

Use of symptom-guided physical activity and exercise rehabilitation for COVID-19 and other postviral conditions

There are many similarities in symptoms between postviral conditions, including clinical features such as fatigue, reduced daily activity and postexertional symptom exacerbation. Unfavourable responses to exercise have influenced the wider debate on how to reintegrate physical activity (PA) and exercise while simultaneously managing symptoms during recovery from post-COVID-19 syndrome (or Long COVID). This has resulted in inconsistent advice from the scientific and clinical rehabilitation community on how and when to resume PA and exercise following COVID-19 illness. This article provides commentary on the following topics: (1) controversies surrounding graded exercise therapy as a treatment modality for post-COVID-19 rehabilitation; (2) evidence supporting PA promotion, resistance exercise and cardiorespiratory fitness for population health, and the consequences of physical inactivity in patients with complex rehabilitation needs; (3) population-based challenges for UK Defence Rehabilitation practitioners for the management of postviral conditions; and (4) 'symptom guided PA and exercise rehabilitation' as an appropriate treatment option for managing individuals with multifaceted medical needs.

Effectiveness of low-load resistance training with blood flow restriction vs. conventional high-intensity resistance training in older people diagnosed with sarcopenia: a randomized controlled trial

Low-load resistance training with blood flow restriction (LRT-BFR) has shown potential to improve muscle strength and mass in different populations; however, there remains limited evidence in sarcopenic people diagnosed with sarcopenia criteria. This study systematically compared the effectiveness of LRT-BFR and conventional high-intensity resistance training (CRT) on clinical muscle outcomes (muscle mass, strength and performance), cardiovascular disease (CVD) risk factors and sarcopenia-related biomarkers of older people with sarcopenia. Twenty-one older individuals (aged 65 years and older) diagnosed with sarcopenia were randomly assigned to the LRT-BFR (20%-30% one-repetition maximum (1RM), n = 10) or CRT (60%-70% 1RM, n = 11) group. Both groups underwent a supervised exercise program three times a week for 12 weeks. The primary outcome was knee extensor strength (KES), and the secondary outcomes included body composition (body mass, body mass index and body fat percentage), muscle mass [appendicular skeletal muscle mass index (ASMI)], handgrip strength, physical performance [short physical performance battery (SPPB) and 6-m walk], CVD risk factors [hemodynamic parameters (systolic and diastolic blood pressure and heart rate (SBP, DBP and HR)) and lipid parameters (total cholesterol, triglyceride (TG), high-density lipoprotein (HDL) and low-density lipoprotein)], sarcopenia-related blood biomarkers [inflammatory biomarkers, hormones (growth hormone (GH) and insulin-like growth factor 1) and growth factors (myostatin and follistatin)] and quality of life [Short Form 36 Health Survey (SF-36)]. Both interventions remarkably improved the body composition, KES, 6-m walk, SBP, HDL, TG, GH, FST and SF-36 scores. CRT significantly improved the ASMI (p < 0.05) and SPPB (p < 0.05). A significant improvement in HR was observed only after LRT-BFR. No significant between-group differences were found before and after the interventions. This study suggested that LRT-BFR and CRT are beneficial to the clinical muscle outcomes, CVD risk factors and certain sarcopenia-related biomarkers of older people with sarcopenia. By comparison, CRT seems more effective in improving muscle mass, while LRT-BFR may be more beneficial for improving cardiovascular health in this population. Therefore, LRT-BFR is a potential alternative to CRT for aging sarcopenia.

Feasibility and safety of two weeks of blood flow restriction exercise in individuals with spinal cord injury

CONTEXT

Reduced muscle strength and function are common after spinal cord injury (SCI). While low-load blood flow restriction exercise (BFRE) enhances muscle strength in healthy and clinical populations, its safety and feasibility in individuals with SCI remain underexplored.

OBJECTIVES

To investigate the feasibility and safety of low-load BFRE in individuals with incomplete SCI.

STUDY DESIGN

Case series.

SETTING

SCI rehabilitation center.

PARTICIPANTS

Six participants with motor incomplete SCI were enrolled in the study.

INTERVENTION

A two-week BFRE intervention for the lower limbs was conducted twice weekly at 40% total arterial occlusion pressure, using 30-40% of 1-repetition maximum loads.

OUTCOME MEASURES

Feasibility measures, specifically recruitment and eligibility rates and intervention acceptability, were collected. Blood pressure (BP) responses and specific coagulation markers for deep vein thrombosis (DVT) were assessed as safety measures.

RESULTS

Recruitment and eligibility rates were 2.8% and 6.6% for individuals admitted for first-time rehabilitation (subacute SCI) and 8.3% and 13.9% for 4-week readmission rehabilitation stays (chronic SCI), respectively. Intervention acceptability was high, characterized by 95.8% training adherence and low-to-moderate self-reported pain levels. BP responses and changes in C-reactive protein, Fibrinogen, and D-dimer during the intervention remained within clinically acceptable levels.

CONCLUSION

BFRE was feasible in an SCI rehabilitation setting despite a low recruitment rate. BFRE imposed no heightened risk of DVT or severe BP fluctuations in the present case series. Additionally, no severe adverse events occurred, and only mild complaints were reported. More extensive safety considerations warrant larger-scale exploration.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT03690700.

Local, proximal, and distal effects of resistance training with blood flow restriction on strength and size of upper limb muscles in healthy individuals: A systematic review

INTRODUCTION

Resistance training with blood flow restriction (BFR) can promote gains in muscle strength and size using low-load protocols.

OBJECTIVE

To gather the evidence on local, proximal, and distal effects of resistance training with BFR on the strength and size of upper limb muscles in healthy individuals.

METHODS

Searches were performed in CENTRAL, PEDro, MEDLINE, SciELO, SCOPUS, and Science Direct databases from inception to March 2023. Clinical trials that compared the effects of resistance training with and without BFR (≥4 weeks) on the strength and size of upper limb muscles in healthy individuals were included. Data related to studies' participants, BFR techniques, resistance training protocols, outcomes and assessment measures, and main results were collected. The risk of bias and quality of evidence was assessed using the Cochrane Risk of Bias Analysis Tool and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach, respectively.

RESULTS

Twenty-three studies with a low-high risk of bias and a very-low-to-high quality were included in this review. In general, findings suggest that either high- or low-load resistance training with BFR provided greater local, proximal, and/or distal gains in muscle size and strength compared to resistance training without BFR.

CONCLUSIONS

Resistance training with BFR can increase the strength and size of upper limb muscles in healthy individuals. Caution must be taken when interpreting and generalizing the results gathered in this review high heterogeneity of the included studies' methods.

Effects of blood flow restriction training on aerobic capacity, lower limb muscle strength and mass in healthy adults: a meta-analysis

INTRODUCTION

The aim of this study was to systematically evaluate the effects of blood flow restriction combined with aerobic exercise on aerobic capacity, lower limb muscle strength and mass in healthy adults.

EVIDENCE ACQUISITION

According to PRISMA's statement, we searched Web of science, Medline, Embase, Cochrane library, CNKI, Wan fang, and VIP databases to collect randomized controlled trials on the effects of aerobic exercise with blood flow restriction on improving aerobic capacity, lower limb muscle strength, and muscle mass in healthy adults. The studies were published from the establishment of the database to November 2023. A supplementary search has been conducted on March 8, 2024. Review Manager5.3 and Stata17 were used for statistical analysis.

EVIDENCE SYNTHESIS

A total of 16 RCTs with 388 participants were included. The results of meta-analysis showed: Aerobic exercise with BFR significantly affected aerobic capacity (MD and 95%CI 1.06[0.29,1.83], P<0.05), lower limb muscle strength (MD and 95%CI 7.56[5.80,9.33], P<0.05) and lower limb muscle mass (MD and 95%CI were 3.02[1.63,4.42], P<0.05) in healthy adults. The results of subgroup analysis showed that intermittent pressure was better than continuous pressure (P<0.05). Compared with the elderly, the effect of young and middle-aged was better (P<0.05). At the same time, the training form using power bikes is better than walking or running. Finally, 2-6 weeks, 2-3 sessions per week, 10-45 minutes per session can effectively improve the aerobic capacity of healthy adults.

CONCLUSIONS

Aerobic exercise with BFR can significantly improve aerobic capacity, lower limb muscle strength and mass in healthy adults. In the future, the effects of blood flow restriction training on healthy adults should be further studied, and the form of pressure, intervention cycle, frequency, time, intensity and other variables should be further controlled.

Enhancing upper extremity muscle strength in individuals with spinal cord injury using low-intensity blood flow restriction exercise

OBJECTIVES

This study explores the feasibility and effects of low-intensity blood flow restriction exercise on forearm muscle strength and function in individuals with spinal cord injury.

STUDY DESIGN

Pilot randomized clinical trial.

PATIENTS AND METHODS

Ten male and female adult participants with chronic cervical and thoracic spinal cord injury underwent an 8-week low-intensity blood flow restriction exercise programme that targeted forearm muscles. Each participant's contralateral forearm served as the control. Grip strength was the primary outcome measure, and participants also provided qualitative feedback on their experiences.

RESULTS

The study revealed a significant increase in participants' forearm muscle strength on the experimental side engaged in low-intensity blood flow restriction training, with an average strength gain of 7.5 ± 0.36 kg after 16 exercise sessions (Cohen's d = -6.32, 95% CI -8.34, -6.68). In comparison, the control side, following a conventional high- intensity exercise regimen without BFR, showed a more modest strength increase of 4.4 ± 0.67 kg. A mean Patient's Global Impression of Change score of 2.2 reflected overall improvements in participants' daily activities and health status.

CONCLUSION

This study highlights the feasibility and effectiveness of low-intensity blood flow restriction exercise as a safe and promising approach to enhancing forearm muscle strength in individuals with spinal cord injury. The observed positive outcomes, coupled with a high level of participant satisfaction, underscore the potential of this innovative method to significantly improve limb muscle strength, thereby contributing to greater functional independence in this population.

The Effect of Blood Flow Restriction during Low-Load Resistance Training Unit on Knee Flexor Muscle Fatigue in Recreational Athletes: A Randomized Double-Blinded Placebo-Controlled Pilot Study

Background/Objectives: Despite the growing popularity of training with a controlled form of vascular occlusion, known as blood flow restriction (BFR) training, in the rehabilitation of orthopedic patients and sports medicine, there remains ample space for understanding the basis of its mechanism. The pilot study assessed the effect of BFR during a low-load resistance training unit on knee flexor muscle fatigue, intending to decide whether a larger trial is needed and feasible. Methods: The study used a prospective, randomized, parallel, double-blind, placebo-controlled design. Fifteen male healthy recreational athletes were randomly assigned to three equal groups: BFR Group, Placebo Group, and Control Group. The primary outcome was the change in the surface electromyography-based (sEMG-based) muscle fatigue index, which was determined by comparing the results obtained before and after the intervention. The intervention was the application of BFR during low-load resistance training for knee flexors. The occurrence of any adverse events was documented. Results: In all groups, the sEMG-based fatigue index for semitendinosus and biceps femoris muscles decreased after low-load resistance training, with the largest decrease in the BFR group. Although not statistically significant, BFR showed moderate and large effect sizes for the fatigue index of semitendinosus and biceps femoris, respectively. No adverse events were noted. Conclusions: The pilot study suggested that BFR during a low-load resistance training unit might affect knee flexor muscle fatigue, supporting the development of a larger randomized clinical trial.

Effect of Aerobic Training with Blood Flow Restriction on Strength and Hypertrophy: A Meta-analysis

The objective of this meta-analysis is to compare the effects on muscle strength and hypertrophy of low and high-intensity aerobic training with BFR (LI-BFR and HI-BFR) versus low and high-intensity aerobic training without BFR (LI and HI). The search was performed in five databases, by two independent researchers, and the terms and keywords used to optimize the searches were related to blood flow restriction and aerobic training. All studies were evaluated for methodological quality using the PEDro scale and for quality of evidence using the GRADE system. Meta-analyses were conducted using RevMan software. After data extraction, 11 studies met all eligibility criteria and were included in the systematic review. The results of the overall analysis between LI-BFR vs. LI showed a significant difference in muscle strength of knee extensors; for hypertrophy, LI was superior to LI-BFR with clinical relevance. Comparing HI-BFR vs. HI there was no superiority for muscle strength. In conclusion, for strength gains very low-quality evidence was found to support no superiority between LI-BFR and HI-BFR compared to LI and HI, respectively. For muscle hypertrophy, superiority of LI was found compared to LI-BFR, with a very low level of evidence.

Effect of blood flow restriction training on health promotion in middle-aged and elderly women: a systematic review and meta-analysis

Background: Physical activities play an important role in alleviating the aging problem and improving the physical fitness of middle-aged and elderly people. Blood flow restriction (BFR) training, also known as pressure training, has been widely used to improve athletes' performance and rehabilitation, which is a relatively novel exercise method for improving the physical fitness of middle-aged and elderly people. The purpose of this study is to conduct a systematic review and meta-analysis of domestic and foreign randomized controlled trial studies on BFR training for middle-aged and elderly women, further explore the impact of BFR training on health status. Methods: Meta-analysis was performed according to PRISMA standards, and charts were drawn using Review Manager 5.4 and Stata 17 software. In this study, the keywords such as "pressure training", "blood restriction training", "elderly women", "KAATSU", "blood flow restriction training" were used on CNKI, China Science and Technology Journal Database, PubMed, Embase, Web of Science, Cochrane Library, EBSCO, Scopus, and randomized controlled trials were searched in all languages. The search was performed from the establishment of database to 2 January 2024. The results of the combined effect were represented by standard mean differences. Results: Among the 681 literature retrieved, six eligible English articles were included in this meta-analysis. The overall effect test of the combined effect was performed on 10 groups of data, and the results were SMD = -0.18 (95%CI: -0.91 to 0.56; p > 0.05), the maximum dynamic force of 1RM SMD = 0.97 (95%CI: 0.35 to 1.58; p < 0.05), leg compression force SMD = -0.10 (95%CI: -0.78 to 0.57; p > 0.05), heart rate SMD = 0.33 (95%CI: -2.50 to 3.17; p > 0.05), systolic blood pressure (SBP) SMD = -1.44 (95%CI: -2.17 to -0.70; p < 0.05), diastolic blood pressure (DBP) SMD = -0.69 (95%CI: 2.54 to 1.15; p > 0.05). Conclusion: BFR training had a significant effect on the increase of the maximum dynamic force of 1RM and decrease of blood pressure in middle-aged and elderly women, but there was no significant difference found in heart rate and leg compression force. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/, identifier CRD42024491642.

Aerobic Training With Blood Flow Restriction on Muscle Hypertrophy and Strength: Systematic Review and Meta-analysis

ABSTRACT

de Lemos Muller, CH, Farinha, JB, Leal-Menezes, R, and Ramis, TR. Aerobic training with blood flow restriction on muscle hypertrophy and strength: systematic review and meta-analysis. J Strength Cond Res 38(7): 1341-1349, 2024-Integrating strength and endurance training in a single exercise session, even on separate days, can be physically demanding and time-consuming. Therefore, there is a growing interest in identifying efficient training methods that can concurrently enhance cardiovascular and neuromuscular performance through a singular training modality. This study conducted a systematic review and meta-analysis to explore the effects of aerobic training with blood flow restriction (AT + BFR) on muscle hypertrophy and strength gains in healthy individuals. Our study was registered at PROSPERO and used multiple databases (PubMed, Embase, Scopus, and Web of Science), seeking clinical trials that examined AT + BFR influence on muscle hypertrophy and strength gains in individuals aged 18-60 years and comparing with aerobic training without BFR. The risk of bias and method quality were assessed using the ROB2.0 tool and PEDro scale, respectively, and the quality of evidence was evaluated with the GRADE method. A random-effects model was used for meta-analysis, and standardized mean difference (SMD) was calculated for each outcome. Of 4,462 records, 29 full texts were assessed for eligibility, with 7 articles meeting the inclusion criteria. The results indicated that AT + BFR was more beneficial for inducing muscle hypertrophy than aerobic training without BFR (SMD [95% CI] = 0.86 [0.37-1.35]; I2 = 42%). Furthermore, AT + BFR was associated with greater improvements in muscle strength (SMD [95% CI] = 0.41 [0.10-0.72]; I2 = 0%). Despite the generally high risk of bias for both outcomes, these encouraging findings underscore the clinical significance of AT + BFR as a compelling tool for enhancing neuromuscular parameters.

Influence of Blood Flow Restriction on Neuromuscular Function and Fatigue During Forearm Flexion in Men

ABSTRACT

Montgomery, TR Jr, Olmos, A, Sears, KN, Succi, PJ, Hammer, SM, Bergstrom, HC, Hill, EC, Trevino, MA, and Dinyer-McNeely, TK. Influence of blood flow restriction on neuromuscular function and fatigue during forearm flexion in men. J Strength Cond Res 38(7): e349-e358, 2024-To determine the effects of blood flow restriction (BFR) on the mean firing rate (MFR) and motor unit action potential amplitude (MUAPAMP) vs. recruitment threshold (RT) relationships during fatiguing isometric elbow flexions. Ten men (24.5 ± 4.0 years) performed isometric trapezoidal contractions at 50% maximum voluntary contraction to task failure with or without BFR, on 2 separate days. For BFR, a cuff was inflated to 60% of the pressure required for full brachial artery occlusion at rest. During both visits, surface electromyography was recorded from the biceps brachii of the dominant limb and the signal was decomposed. A paired-samples t test was used to determine the number of repetitions completed between BFR and CON. ANOVAs (repetition [first, last] × condition [BFR, CON]) were used to determine differences in MFR vs. RT and MUAPAMP vs. RT relationships. Subjects completed more repetitions during CON (12 ± 4) than BFR (9 ± 2; p = 0.012). There was no significant interaction (p > 0.05) between the slopes and y-intercepts during the repetition × condition interaction for MUAPAMP vs. MFR. However, there was a main effect of repetition for the slopes of the MUAPAMP vs. RT (p = 0.041) but not the y-intercept (p = 0.964). Post hoc analysis (collapsed across condition) indicated that the slopes of the MUAPAMP vs. RT during the first repetition was less than the last repetition (first: 0.022 ± 0.003 mv/%MVC; last: 0.028 ± 0.004 mv/%MVC; p = 0.041). Blood flow restriction resulted in the same amount of higher threshold MU recruitment in approximately 75% of the repetitions. Furthermore, there was no change in MFR for either condition, even when taken to task failure. Thus, BFR training may create similar MU responses with less total work completed than training without BFR.

Five-Week, Low-Intensity Blood Flow Restriction Rowing Improves V̇ o2 max in Elite Rowers

ABSTRACT

Held, S, Rappelt, L, Rein, R, Deutsch, J-P, Wiedenmann, T, and Donath, L. Five-week, low-intensity, blood flow restriction rowing improves V̇ o2 max in elite rowers. J Strength Cond Res 38(6): e299-e303, 2024-This controlled intervention study examined the effects of low-intensity rowing with blood flow restriction (BFR) on maximal oxygen uptake (V̇ o2 max), peak power output during ramp testing (PPO), and 2000-m time trial performance (P2k). Eleven, highly elite, male rowers (22.1 ± 1.6 years; 92.6 ± 3.8 kg; 1.93 ± 0.04 m; 7.9. ± 2.2 years rowing experience; 20.4 ± 2.0 h·w -1 training volume; 11.9 ± 1.1 session per week) trained 5 weeks without BFR (Base) followed by a 5-week BFR intervention period. BFR of the lower limb was applied through customized elastic wraps. BFR took place 3 times a week (accumulated net pBFR: 60 min·wk -1 ; occlusion per session: 2 times 10 min·session -1 ) and was used exclusively at low intensities (<2 mmol·L -1 ). V̇ o2 max, PPO, and P2k were examined before, between, and after both intervention periods. Bayesian's credible intervals revealed relevantly increased V̇ o2 max +0.30 L·min -1 (95% credible interval: +0.00 to +0.61 L·min -1 ) adaptations through BFR. By contrast, PPO +14 W (-6 to +34 W) and P2k -5 W (-14 to +3 W) were not noticeably affected by the BFR intervention. This study revealed that 15 sessions of BFR application with a cumulative total BFR load of 5 h over a 5-week macrocycle increased V̇ o2 max remarkably. Thus, pBFR might serve as a promising tool to improve aerobic capacity in highly trained elite rowers.

Effects of Low-Load Blood Flow Restriction Training on Rotator Cuff Strength and Hypertrophy: Case Series

Background

The rotator cuff (RC) plays a pivotal role in the performance and health of the shoulder and upper extremity. Blood flow restriction training (BFRT) is a modality to improve strength and muscle hypertrophy with even low-load training in healthy and injured individuals. There is minimal evidence examining its effect proximal to the occluded area, and particularly on the RC.

Hypothesis & Purpose

The purpose of this case series is to explore the effects of low-load BFRT on RC strength, hypertrophy, and tendon thickness in asymptomatic individuals.

Study Design

Case series.

Methods

Fourteen participants with asymptomatic, untrained shoulders were recruited to participate. They performed an eight-week low-load shoulder exercise regimen where BFR was applied to the dominant arm only during exercise. The dependent variables were maximal isometric strength of the shoulder external rotators(ER) and elevators (in the scapular plane in full can position) (FC) measured via handheld dynamometry, cross sectional area (CSA) of the supraspinatus and infraspinatus muscles, and supraspinatus tendon thickness measured via ultrasound imaging (US). Mean changes within and between arms were compared after training using paired t-tests. Cohen's d was used to determine effect sizes.

Results

All participants were able to complete the BFRT regimen without adverse effects. Mean strength and CSA increased for all variables in both arms, however this increase was only significant (p\<0.01) for FC strength bilaterally and CSA for the supraspinatus and infraspinatus on the BFRT side. The effect sizes for increased supraspinatus and infraspinatus CSA on the BFRT side were 0.40 (9.8% increase) and 0.46 (11.7% increase) respectively. There were no significant differences when comparing the mean changes of the BFRT side to the non-BFRT side for strength or muscle CSA. There were no significant changes to supraspinatus tendon thickness.

Conclusion

These results suggest variability in response of the RC musculature to low-load BFRT in asymptomatic individuals. The potential for a confounding systemic response in the study design makes determining whether low-load BFRT is more beneficial than low-load non-BFRT difficult. The hypertrophy seen on the BFRT side warrants further study.

Level of Evidence

4.

Potential Moderators of the Effects of Blood Flow Restriction Training on Muscle Strength and Hypertrophy: A Meta-analysis Based on a Comparison with High-Load Resistance Training

BACKGROUND

While it has been examined whether there are similar magnitudes of muscle strength and hypertrophy adaptations between low-load resistance training combined with blood-flow restriction training (BFR-RT) and high-load resistance training (HL-RT), some important potential moderators (e.g., age, sex, upper and lower limbs, frequency and duration etc.) have yet to be analyzed further. Furthermore, training status, specificity of muscle strength tests (dynamic versus isometric or isokinetic) and specificity of muscle mass assessments (locations of muscle hypertrophy assessments) seem to exhibit different effects on the results of the analysis. The role of these influencing factors, therefore, remains to be elucidated.

OBJECTIVES

The aim of this meta-analysis was to compare the effects of BFR- versus HL-RT on muscle adaptations, when considering the influence of population characteristics (training status, sex and age), protocol characteristics (upper or lower limbs, duration and frequency) and test specificity.

METHODS

Studies were identified through database searches based on the following inclusion criteria: (1) pre- and post-training assessment of muscular strength; (2) pre- and post-training assessment of muscular hypertrophy; (3) comparison of BFR-RT vs. HL-RT; (4) score ≥ 4 on PEDro scale; (5) means and standard deviations (or standard errors) are reported or allow estimation from graphs. In cases where the fifth criterion was not met, the data were requested directly from the authors.

RESULTS

The main finding of the present study was that training status was an important influencing factor in the effects of BFR-RT. The trained individuals may gain greater muscle strength and hypertrophy with BFR-RT as compared to HL-RT. However, the results showed that the untrained individuals experienced similar muscle mass gains and superior muscle strength gains in with HL-RT compared to BFR-RT.

CONCLUSION

Compared to HL-RT, training status is an important factor influencing the effects of the BFR-RT, in which trained can obtain greater muscle strength and hypertrophy gains in BFR-RT, while untrained individuals can obtain greater strength gains and similar hypertrophy in HL-RT.

Physiological and perceptual responses to acute arm cranking with blood flow restriction

INTRODUCTION

Lower-body aerobic exercise with blood flow restriction (BFR) offers a unique approach for stimulating improvements in muscular function and aerobic capacity. While there are more than 40 reports documenting acute and chronic responses to lower-body aerobic exercise with BFR, responses to upper-body aerobic exercise with BFR are not clearly established.

PURPOSE

We evaluated acute physiological and perceptual responses to arm cranking with and without BFR.

METHODS

Participants (N = 10) completed 4 arm cranking (6 × 2 min exercise, 1 min recovery) conditions: low-intensity at 40%VO2peak (LI), low-intensity at 40%VO2peak with BFR at 50% of arterial occlusion pressure (BFR50), low-intensity at 40%VO2peak with BFR at 70% of arterial occlusion pressure (BFR70), and high-intensity at 80%VO2peak (HI) while tissue oxygenation, cardiorespiratory, and perceptual responses were assessed.

RESULTS

During exercise, tissue saturation for BFR50 (54 ± 6%), BFR70 (55 ± 6%), and HI (54 ± 8%) decreased compared to LI (61 ± 5%, all P < 0.01) and changes in deoxyhemoglobin for BFR50 (11 ± 4), BFR70 (15 ± 6), and HI (16 ± 10) increased compared to LI (4 ± 2, all P < 0.01). During recovery intervals, tissue saturation for BFR50 and BFR70 decreased further and deoxyhemoglobin for BFR50 and BFR70 increased further (all P < 0.04). Heart rate for BFR70 and HI increased by 9 ± 9 and 50 ± 15b/min, respectively, compared to LI (both P < 0.02). BFR50 (8 ± 2, 1.0 ± 1.0) and BFR70 (10 ± 2, 2.1 ± 1.4) elicited greater arm-specific perceived exertion (6-20 scale) and pain (0-10 scale) compared to LI (7 ± 1, 0.2 ± 0.5, all P < 0.05) and pain for BFR70 did not differ from HI (1.7 ± 1.9).

CONCLUSION

Arm cranking with BFR decreased tissue saturation and increased deoxyhemoglobin without causing excessive cardiorespiratory strain and pain.

Outcomes of Blood Flow Restriction Training After ACL Reconstruction in NCAA Division I Athletes

Background

Blood flow restriction training (BFRT) is a safe and potentially effective adjunctive therapeutic modality for postoperative rehabilitation related to various knee pathologies. However, there is a paucity of literature surrounding BFRT in high-performance athletes after anterior cruciate ligament reconstruction (ACLR).

Purpose

To (1) compare the overall time to return to sports (RTS) in a cohort of National Collegiate Athletic Association (NCAA) Division I athletes who underwent a standardized rehabilitation program either with or without BFRT after ACLR and (2) identify a postoperative time interval for which BFRT has the maximum therapeutic benefit.

Study Design

Cohort study; Level of evidence, 3.

Methods

A total of 55 student-athletes who underwent ACLR between 2000 and 2023 while participating in NCAA Division I sports at a single institution were included in this study. Athletes were allocated to 1 of 2 groups based on whether they participated in a standardized postoperative rehabilitation program augmented with BFRT (BFRT group; n = 22) or completed the standardized protocol alone (non-BFRT group [control]; n = 33). Our primary outcome measure was time to RTS. The secondary outcome measure was handheld dynamometry quadriceps strength testing at various postoperative time points, converted to a limb symmetry index (LSI). Quadriceps strength was not tested between the BFRT and non-BFRT groups because of the limited amount of data on the control group.

Results

The mean age at the date of surgery was 18.59 ± 1.10 years for the BFRT group and 19.45 ± 1.30 years for the non-BFRT group (P = .011), and the mean RTS time was 409 ± 134 days from surgery for the BFRT group and 332 ± 100 days for the non-BFRT cohort (P = .047). For the BFRT group, the mean quadriceps strength LSI increased by 0.67% (95% CI, 0.53%-0.81%) for every week of rehabilitation, and there was a significantly positive rate of change in quadriceps strength in weeks 13-16 compared with weeks 9-12 (ΔLSI, 8.22%; P < .001).

Conclusion

In elite NCAA Division I athletes, a statistically significant delay was observed in RTS with BFRT compared with standardized physical therapy alone after undergoing ACLR. There also appeared to be an early window during the rehabilitation period where BFRT had a beneficial impact on quadriceps strength.

Neuromuscular Responses and Perceptions of Health Status and Pain-Related Constructs in End-Stage Knee Osteoarthritis During Resistance Training With Blood Flow Restriction

ABSTRACT

Ogrezeanu, DC, López-Bueno, L, Sanchís-Sánchez, E, Carrasco, JJ, Cuenca-Martínez, F, Suso-Martí, L, López-Bueno, R, Cruz-Montecinos, C, Martinez-Valdes, E, Casaña, J, and Calatayud, J. Neuromuscular responses and perceptions of health status and pain-related constructs in end-stage knee osteoarthritis during resistance training with blood flow restriction. J Strength Cond Res 38(4): 762-772, 2024-We aimed to evaluate the neuromuscular responses and their relationship with health status, kinesiophobia, pain catastrophizing, and chronic pain self-efficacy in patients with end-stage knee osteoarthritis during acute resistance training with different levels of blood flow restriction (BFR). Seventeen patients with end-stage knee osteoarthritis participated in 3 experimental sessions separated by 3 days, performing 4 sets of knee extensions with low load and 3 levels of concurrent BFR performed in a random order: control (no BFR), BFR at 40% arterial occlusion pressure (AOP), and BFR at 80% AOP. Normalized root-mean-square (nRMS), nRMS spatial distribution (centroid displacement, modified entropy, and coefficient of variation), and normalized median frequency (nFmed) were calculated from the vastus medialis (VM) and lateralis (VL) using high-density surface electromyography. Subjects were asked to report adverse effects after the sessions. In the VM, nRMS was higher with 80% AOP than with 40% AOP ( p = 0.008) and control ( p < 0.001), whereas there were no differences between conditions in the VL. Normalized root-mean-square also showed an association with pain catastrophizing, chronic pain self-efficacy, and health status (VM: -0.50, 0.49, -0.42; VL: -0.39, 0.27, -0.33). Spatial distribution varied between conditions but mostly in the VL. Overall, nFmed did not vary, with only a slight increase in the VL with 40% AOP, between set 3 and 4. BFR during knee extensions at 80% AOP increases VM activity and VL amplitude distribution more than 40% AOP and control. Importantly, muscle activity increases are modulated by pain catastrophizing, chronic pain self-efficacy, and health status in these patients, and kinesiophobia seems to especially modulate entropy.

Development of a prediction equation to estimate lower-limb arterial occlusion pressure with a thigh sphygmomanometer

INTRODUCTION

Previous investigators have developed prediction equations to estimate arterial occlusion pressure (AOP) for blood flow restriction (BFR) exercise. Most equations have not been validated and are designed for use with expensive cuff systems. Thus, their implementation is limited for practitioners.

PURPOSE

To develop and validate an equation to predict AOP in the lower limbs when applying an 18 cm wide thigh sphygmomanometer (SPHYG18cm).

METHODS

Healthy adults (n = 143) underwent measures of thigh circumference (TC), skinfold thickness (ST), and estimated muscle cross-sectional area (CSA) along with brachial and femoral systolic (SBP) and diastolic (DBP) blood pressure. Lower-limb AOP was assessed in a seated position at the posterior tibial artery (Doppler ultrasound) using a SPHYG18cm. Hierarchical linear regression models were used to determine predictors of AOP. The best set of predictors was used to construct a prediction equation to estimate AOP. Performance of the equation was evaluated and internally validated using bootstrap resampling.

RESULTS

Models containing measures of either TC or thigh composition (ST and CSA) paired with brachial blood pressures explained the most variability in AOP (54%) with brachial SBP accounting for majority of explained variability. A prediction equation including TC, brachial SBP, and age showed good predictability (R2 = 0.54, RMSE = 7.18 mmHg) and excellent calibration. Mean difference between observed and predicted values was 0.0 mmHg and 95% Limits of Agreement were ± 18.35 mmHg. Internal validation revealed small differences between apparent and optimism adjusted performance measures, suggesting good generalizability.

CONCLUSION

This prediction equation for use with a SPHYG18cm provided a valid way to estimate lower-limb AOP without expensive equipment.

[Current approach in the follow-up treatment of joint-preserving operations on the knee joint in German-speaking countries]

INTRODUCTION

Postoperative follow-up after joint-preserving knee surgery involves conventional physiotherapy as well as other approaches and devices such as CPM and CAM splints, TENS devices, BFR exercise, prehabilitation, and digital health applications. The aim of this survey was to investigate current standards, trends and control methods in postoperative care to identify fields of concern and to compare them with the current literature.

MATERIAL AND METHODS

We conducted a structured anonymous online survey of specialists in orthopaedics and trauma surgery listed by the German-speaking Society for Arthroscopy and Joint Surgery (AGA). The questionnaire included 36 closed-ended questions on the follow-up of joint-preserving surgery of the knee joint.

RESULTS

Questionnaires from 528 participants with long-term professional experience (86.6% with more than 10 years) were analysed. Standardised post-treatment schemes are used by 97.2% and their evidence is estimated to be high (59.1%) / very high (14.8%). Problems of rehabilitation are seen in 10-20% of cases by 87.3% (persistent muscular atrophy 30.9%). After reconstructive surgery, CPM splints (70.1%), CAM splints (42.1%), orthoses (85.0%) and TENS devices (40.0%) are prescribed. More potent approaches for the treatment of postoperative muscle deficits are desired by 89.4%. BFR exercise is known by 41.7% and is used regularly by 8%. Communication with treating physiotherapists is infrequent (written: 27.5%). Digital rehabilitation management would be supported by 83.3%; 22.7% are not aware of digital health applications. 87.9% of participants believe that prehabilitation can affect postoperative outcomes.

CONCLUSION

Follow-up of knee joint-preserving surgeries is usually standardised and regularly reviewed for up-to-date evidence. The evidence for recommendations made is considered high. Orthoses are usually used after reconstructive surgery, persistent muscle atrophy is a major problem, BFR training is only known to a limited extent, and there is currently a lack of standardised training protocols. Communication with physiotherapists needs to be improved. Digital rehabilitation management is rarely used but would be supported by the majority of surgeons.

Quadriceps vascular occlusion does not alter muscle action or balance: A cross-sectional study

Background

Partial vascular occlusion (PVO) can increase muscle strength and hypertrophy without joint overload. However, PVO could increase the possibility of imbalances and injuries during physical activity.

Objectives

To identify changes in strength, muscle activation, and postural control during the use of PVO in young women.

Method

A total of 14 healthy women aged between 18 and 30 years were evaluated. Dynamometry was used to analyse the strength of the quadriceps muscle, and surface electromyography to evaluate quadriceps muscle activity. A force platform was utilised to assess postural control, static single-legged support, single-legged squat, and climbing and descending stairs. Participants were randomly assigned to the evaluations either with or without PVO. The results were compared and correlated.

Results

The performance of static, dynamic, or stair exercises, with or without PVO, did not indicate differences in muscle strength and recruitment (p > 0.05). The use of PVO improved the velocity of anteroposterior (AP) oscillation of static postural control (p = 0.001). We found a moderate negative correlation between muscle strength and postural control during the ascending stairs task with the use of PVO (r = -0.54; r = -0.59), while in the group without PVO, the correlation was moderate to high (r = -0.55; r = -0.76).

Conclusion

The use of PVO did not impair muscle strength and recruitment of the quadriceps or postural control in healthy women.

Clinical Implications

Partial vascular occlusion can be used during dynamic exercises without impairing the balance and muscle strength of the quadriceps during its execution.

Safety and efficacy of blood flow restriction exercise in individuals with neurological disorders: A systematic review

OBJECTIVES

This systematic review evaluated the safety and efficacy of blood flow restriction exercise (BFRE) on skeletal muscle size, strength, and functional performance in individuals with neurological disorders (ND).

METHODS

A literature search was performed in PubMed, CINAHL, and Embase. Two researchers independently assessed eligibility and performed data extraction and quality assessments.

ELIGIBILITY CRITERIA

Study populations with ND, BFRE as intervention modality, outcome measures related to safety or efficacy.

RESULTS

Out of 443 studies identified, 16 were deemed eligible for review. Three studies examined the efficacy and safety of BFRE, one study focused on efficacy results, and 12 studies investigated safety. Disease populations included spinal cord injury (SCI), inclusion body myositis (sIBM), multiple sclerosis (MS), Parkinson's disease (PD), and stroke. A moderate-to-high risk of bias was presented in the quality assessment. Five studies reported safety concerns, including acutely elevated pain and rating of perceived exertion levels, severe fatigue, muscle soreness, and cases of autonomic dysreflexia. Two RCTs reported a significant between-group difference in physical function outcomes, and two RCTs reported neuromuscular adaptations.

CONCLUSION

BFRE seems to be a potentially safe and effective training modality in individuals with ND. However, the results should be interpreted cautiously due to limited quality and number of studies, small sample sizes, and a general lack of heterogeneity within and between the examined patient cohorts.

Chronic hemodynamic adaptations induced by resistance training with and without blood flow restriction in adults: A systematic review and meta-analysis

The purposes of this systematic review and meta-analysis of peer-reviewed literature were to examine the chronic effects of resistance training with blood flow restriction (RT-BFR) on hemodynamics, and to compare these adaptations to those induced by traditional resistance training (TRT) programs in adults (PROSPERO: Registry: CRD42022339510). A literature search was conducted across PubMed, Sports Discus, Scielo, and Web of Science databases. Two independent reviewers extracted study characteristics and blood pressure measures. Risk of bias (The Cochrane risk of bias tool for randomized controlled trials [RoB-2]), and the certainty of the evidence (Grading of Recommendations, Assessment, Development, and Evaluation [GRADE]) were used. A total of eight studies met the inclusion criteria for systolic (SBP), diastolic (DBP), and mean arterial pressure (MAP). Regarding the comparison of RT-BFR vs. non-exercise, no significant differences favoring the exercise group were observed (p ​> ​0.05). However, when compared to TRT, RT-BFR elicited additional improvements on DBP (-3.35; 95%CI -6.00 to -0.71; I2 ​= ​14%; z ​= ​-2.48, p ​= ​0.01), and on MAP (-3.96; 95%CI -7.94 to 0.02; I2 ​= ​43%; z ​= ​-1.95, p ​= ​0.05). Results indicate that RT-BFR may elicit a decrease in DBP in comparison with TRT, but the lack of data addressing this topic makes any conclusion speculative. Future research on this topic is warranted.

Low-intensity resistance exercise with blood flow restriction for patients with claudication: A randomized controlled feasibility trial

BACKGROUND

Claudication is a common and debilitating symptom of peripheral artery disease, resulting in poor exercise performance and quality of life (QoL). Supervised exercise programs are an effective rehabilitation for patients with claudication, but they are poorly adhered to, in part due to the high pain and effort associated with walking, aerobic, and resistance exercise. Low-intensity resistance exercise with blood flow restriction (BFR) represents an alternative exercise method for individuals who are intolerant to high-intensity protocols. The aim of this study was to evaluate the feasibility of a supervised BFR program in patients with claudication.

METHODS

Thirty patients with stable claudication completed an 8-week supervised exercise program and were randomized to either BFR (n = 15) or a control of matched exercise without BFR (control; n = 15). Feasibility, safety, and efficacy were assessed.

RESULTS

All success criteria of the feasibility trial were met. Exercise adherence was high (BFR = 78.3%, control = 83.8%), loss to follow up was 10%, and there were no adverse events. Clinical improvement in walking was achieved in 86% of patients in the BFR group but in only 46% of patients in the control group. Time to claudication pain during walking increased by 35% for BFR but was unchanged for the control. QoL for the BFR group showed improved mobility, ability to do usual activities, pain, depression, and overall health at follow up.

CONCLUSION

A supervised blood flow restriction program is feasible in patients with claudication and has the potential to increase exercise performance, reduce pain, and improve QoL. (Clinicaltrials.gov Identifier: NCT04890275).

An Updated Panorama of Blood-Flow-Restriction Methods

BACKGROUND

Exercise with blood-flow restriction (BFR) is being increasingly used by practitioners working with athletic and clinical populations alike. Most early research combined BFR with low-load resistance training and consistently reported increased muscle size and strength without requiring the heavier loads that are traditionally used for unrestricted resistance training. However, this field has evolved with several different active and passive BFR methods emerging in recent research.

PURPOSE

This commentary aims to synthesize the evolving BFR methods for cohorts ranging from healthy athletes to clinical or load-compromised populations. In addition, real-world considerations for practitioners are highlighted, along with areas requiring further research.

CONCLUSIONS

The BFR literature now incorporates several active and passive methods, reflecting a growing implementation of BFR in sport and allied health fields. In addition to low-load resistance training, BFR is being combined with high-load resistance exercise, aerobic and anaerobic energy systems training of varying intensities, and sport-specific activities. BFR is also being applied passively in the absence of physical activity during periods of muscle disuse or rehabilitation or prior to exercise as a preconditioning or performance-enhancement technique. These various methods have been reported to improve muscular development; cardiorespiratory fitness; functional capacities; tendon, bone, and vascular adaptations; and physical and sport-specific performance and to reduce pain sensations. However, in emerging BFR fields, many unanswered questions remain to refine best practice.

Early- and Late-Stage Benefits of Blood Flow Restriction Training on Knee Strength in Adolescents After Anterior Cruciate Ligament Reconstruction

Background

Blood flow restriction training (BFRT) after anterior cruciate ligament reconstruction (ACLR) is rising in popularity because of its benefits in reducing muscle atrophy and mitigating knee strength deficits.

Purpose

To investigate the impact BFRT has on adolescent knee strength after ACLR at 2 postoperative time points: at 3 months and the time of return to sport (RTS).

Study Design

Cohort study; Level of evidence, 3.

Methods

A prospective intervention (BFRT) group was compared to an age-, sex-, and body mass index-matched retrospective control group. Patients aged 12 to 18 years who underwent primary ACLR with a quadriceps tendon autograft were included. Along with a traditional rehabilitation protocol, the BFRT group completed a standardized BFRT protocol (3 BFRT exercises performed twice weekly for the initial 12 weeks postoperatively). Peak torque values for isometric knee extension and flexion strength (at 3 months and RTS) and isokinetic strength at 180 deg/s (at RTS) as well as Pediatric International Knee Documentation Committee (Pedi-IKDC) scores were collected. Differences between the BFRT and control groups were compared with 2-way mixed analysis of variance and 1-way analysis of variance.

Results

The BFRT group consisted of 16 patients (10 female; mean age, 14.84 ± 1.6 years) who were matched to 16 patients in the control group (10 female; mean age, 15.35 ± 1.3 years). Regardless of the time point, the BFRT group demonstrated significantly higher isometric knee extension torque compared to the control group (2.15 ± 0.12 N·m/kg [95% CI, 1.90-2.39] vs 1.74 ± 0.12 N·m/kg [95% CI, 1.49-1.98], respectively; mean difference, 0.403 N·m/kg; P = .024). The BFRT group also reported significantly better Pedi-IKDC scores compared to the control group at both 3 months (68.91 ± 9.68 vs 66.39 ± 12.18, respectively) and RTS (89.42 ± 7.94 vs 72.79 ± 22.81, respectively) (P = .047).

Conclusion

In adolescents, the addition of a standardized BFRT protocol to a traditional rehabilitation protocol after ACLR significantly improved knee strength and patient-reported function compared to a traditional rehabilitation program alone.