EFFECT OF BLOOD FLOW RESTRICTION TRAINING ON MUSCULAR PERFORMANCE, PAIN AND VASCULAR FUNCTION

PhantomAR: gamified mixed reality system for alleviating phantom limb pain in upper limb amputees-design, implementation, and clinical usability evaluation

BACKGROUND

Phantom limb pain (PLP) is a restrictive condition in which patients perceive pain in a limb that is no longer present, greatly reducing their quality of life. Mirror Therapy, wherein patients observe a mirror reflection of their intact limb, has demonstrated efficacy in alleviating PLP. However, its unilateral and seated nature presents limitations. To address these constraints while still reducing PLP, and evaluating the impact of different virtual limb representations (anthropomorphic vs. non-anthropomorphic) on the user's sense of ownership, agency, and embodiment, PhantomAR was developed. Leveraging wearable first-person augmented reality (AR) technology, PhantomAR extends traditional Mirror Therapy by enabling users to move freely and engage in bimanual tasks.

METHODS

The assistive mixed reality game application PhantomAR was deployed on the Microsoft HoloLens 2 and augmented the user's residual limb by superimposing a virtual arm or tentacle that was controlled via residual muscles on their stump using an EMG electrode array. This setup allowed patients to engage in a first-person perspective and manipulate virtual objects with both the healthy and augmented limbs, free from the confines of a seated position. The study enrolled 10 able-bodied individuals and 8 individuals with unilateral, transradial amputation. All amputees experienced PLP. The usability of the PhantomAR application was evaluated using the System Usability Scale (SUS) and a user-centric survey. Additionally, the Game Experience was assessed on a 5-point Likert questionnaire (GEQ). Participants rated their phantom sensations using the Numerical Rating Scale and McGill Pain Questionnaire before, during, and after interaction with PhantomAR. The embodiment and agency of the virtual superimposed arm were evaluated with an altered Prosthesis Embodiment Scale. The study protocol included two sessions of 30 min each, during which participants experienced PhantomAR.

RESULTS

Participants (n = 18) rated PhantomAR highly usable (SUS m = 90.8%, SD = 6.88). Feedback on the Game Experience Questionnaire was overwhelmingly positive, showing high immersion (m = 4.46, SD = 0.08) and positive affect (m = 4.97, SD = 0.05). PLP (n = 8) significantly decreased post-intervention (NRS and McGill Pain Questionnaire, p < .001). Skin temperature in the residual limb increased significantly post-intervention (p < .01) but did not correlate with PLP (r = - 0.08, p = 0.83). Tentacle overlay yielded mixed ownership but high agency ratings.

CONCLUSION

PhantomAR leverages mixed reality to significantly reduce Phantom Limb Pain, enhance user engagement, and alter perceptions of ownership and agency of their augmented limb through bi-manual, dynamic, full-body interactions. Trial registration DRKS00033208 (Jan. 5th 2024).

The effect of blood flow restriction training on core muscle strength and pain in male collegiate athletes with chronic non-specific low back pain

Objective

The objective of this study is to compare the effectiveness of low-load blood flow restriction training (LL-BFRT) to heavy-load resistance training (HL-RT) in male collegiate athletes with chronic non-specific low back pain (CNLBP).

Methods

Twenty-six participants were randomly assigned to LL-BFRT (n = 13) or HL-RT (n = 13). All participants supervised exercises (deep-squat, lateral pull-down, bench-press and machine seated crunch) cycled 4 times per week for 4 weeks (16 sessions). LL-BFRT was done at 30% 1-repetition maximum (1RM) with 70% arterial occlusion pressure (AOP). HL-RT was done at 70% 1-RM. The outcomes were isokinetic core strength, isometric core endurance, pain intensity, and lumbar function disability level, measured at baseline and 4 weeks. Intra-group differences were evaluated using t-tests.

Results

Pain intensity and function disability level in LL-BFRT had extremely significant improvement at 4 weeks (p < 0.001, ES = 1.44-1.84). Participants in LL-BFRT and HL-RT showed significant differences in core extensors peak torque-body weight ratio (PT/BW) at isokinetic 120°/s and 30°/s, respectively (LL-BFRT: p = 0.045, ES = 0.62; HL-RT: p = 0.013, ES = 0.81). Isometric core extensor endurance was significantly increased in both groups (LL-BFRT: p = 0.016, ES = 0.78; HL-RT: p = 0.011, ES = 0.83).

Conclusion

Four weeks of LL-BFRT significantly reduced pain and functional disability while inducing similar strength gains as HL-RT in male collegiate athletes with CNLBP. Thereby, BFRT may qualify as a valuable training strategy for people with physical limitations.

Low-Load Blood-flow Restriction Training for Medial Tibial Stress-Syndrome in Athletes: A Case Series

Background

Medial tibial stress syndrome (MTSS) is a common overuse injury characterized by activity-induced pain along the distal medial tibial border. Current best practice includes rest and progressive resistance training. However, some patients with MTSS may be unable to tolerate the loading during exercise. Blood-flow restriction training using low loads (LL-BFR) may induce similar physiological and structural adaptations as heavy resistance training but without peak loads. This could potentially allow the athlete to continue sports activities during rehabilitation.

Purpose

The purpose of this case series was to describe an exercise program utilizing LL-BFR training for athletes with running-related MTSS.

Study design

Case series.

Methods

Six recreational athletes (one handball player, one soccer player, and four runners) with MTSS were recruited. Inclusion criteria included pain along the distal two-thirds medial tibial border occurring during or after activity. Exclusion criteria were symptoms of compartment syndrome, tibial stress fracture, or contraindications for BFR training. Participants underwent a progressive six-week home-based LL-BFR training intervention with three sessions per week and were allowed to continue sports activities if pain was ≤ NRS 5. Outcome measures included change in standardized running performance (distance and pain level), pain pressure threshold (algometry), and self-reported physical function.

Results

Five athletes experienced improvements in running performance (pain and/or distance) and self-reported function. One athlete sustained an injury unrelated to the LL-BFR training, and therefore the running post-test could not be completed. Adherence to exercise was high, and post-test interviews revealed positive feedback on the training method, with no side effects reported.

Conclusion

This case series demonstrated that following a therapeutic exercise program utilizing LL-BFR training improvements in pain and function were seen in athletes with MTSS. BFR may allow clinicians to prescribe lower-load exercises, facilitating continued sports participation. Future research should compare the effectiveness of exercise programs for MTSS with and without LL-BFR training.

Level of Evidence

Level V.

Effects of Different Blood Flow Restriction Training Modes on Body Composition and Maximal Strength of Untrained Individuals

BACKGROUND

The objective of this study was to examine the impacts of absolute cuff pressure blood flow restriction (A-BFR) training and incremental cuff pressure blood flow restriction (I-BFR) training, under equal cuff pressures, on body composition and maximal strength among untrained adults. Additionally, we aimed to compare these effects with those observed in high-load resistance training (HL-RT).

METHODS

Thirty-three adults without prior professional sports or resistance training experience were recruited and randomly assigned to three groups (n = 11 per group) for an 8-week training program, held three times weekly. The A-BFR group trained with a 20% 1RM load and a cuff occlusion pressure set at 190 mmHg. The I-BFR group initiated training with an occlusion pressure of 160 mmHg, which incrementally increased by 20 mmHg every two weeks, with other conditions mirroring those of the A-BFR group. The HL-RT group trained with a 70% 1RM load.

RESULTS

All three groups demonstrated a statistically significant improvement in lower-body maximal strength (p < 0.01), with no significant differences observed among the groups (p > 0.05). A notable increase in left-leg muscle mass was seen across all groups (p < 0.05). However, total muscle mass, right-leg muscle mass, fat-free mass, BMI, bone mineral density, and bone mineral content remained relatively unchanged (p > 0.05), with no significant differences among the groups (p > 0.05). Only the HL-RT group exhibited a significant increase in left-leg thigh circumference (p < 0.05), while right-leg thigh circumference remained stable (p > 0.05), with no significant intergroup differences (p > 0.05).

CONCLUSIONS

While A-BFR and I-BFR did not yield statistically significant differences in overall training outcomes, A-BFR demonstrated a slightly stronger potential. A-BFR and I-BFR achieved comparable gains in muscle strength and improvements in body composition to those seen with HL-RT. However, HL-RT demonstrated more significant improvements in leg circumference.

Heart Rate and Blood Pressure Responses Vary Between Blood Flow Restriction Cuff Type

The purpose of the study was to compare heart rate (HR), systolic blood pressure (SBP), and diastolic blood pressure (DBP) following high load resistance exercise (HLRE) and blood flow restriction exercise (BFRE) with a knee wrap (kBFRE) and pneumatic cuff (pBFRE). Eleven men (N = 9) and women (N = 2) participated. HR, SBP, and DBP were collected at Rest, immediately post exercise (IP), 10-, 30-, and 45-minutes post exercise. Repeated measures ANOVAs assessed the effects of condition across time on all variables. Significant effects were examined with pairwise comparisons and a Sidak correction. Significance was defined a priori p ≤ 0.05. There were significant condition by time interactions for HR (p = 0.005; ES = 0.31), SBP (p = 0.016; ES = 0.27), and DBP (p = 0.03; ES = 0.24). There were significant main effects of time for HR (p < 0.001; ES = 0.78), SBP (p < 0.001; ES = 0.84), and DBP (p = 0.004; ES = 0.44). The HR was increased from Rest for up to 45 minutes across all conditions. IP, the HR was lower following pBFRE compared to HLRE. There was an increase in SBP at IP. SBP was higher following HLRE compared to kBFRE and pBFRE. DBP was decreased at 10 minutes across all conditions, with kBFRE prompting larger reductions compared to HLRE at 10 minutes. DBP was lower following kBFRE compared to pBFRE at 45 minutes. This study suggests that BFRE alters cardiovascular function differently than HLRE, but is dependent on cuff type. Specifically, pneumatic cuffs may attenuate the increase in the HR and SBP response, and knee wraps augment the reduction in DBP.

Cardiovascular, perceptual, and performance responses to single- vs. multi-chambered blood flow restriction cuffs

Introduction

This study aimed to investigate the impact of the blood flow restriction bladder type (single- [SC-BFR] vs. multi-chambered [MC-BFR]) on exercise performance, cardiovascular responses, and perceptual experiences with exercise sessions incorporating multiple sets to volitional failure in a randomized, crossover experimental design.

Methods

Twenty-seven healthy, physically active participants (age: 22.6 ± 5.7; weight: 74.3 ± 15.8 kg; height: 171.7 ± 7.7 cm; BMI: 25.0 ± 4.1 kg/m2; ∼93% reported regular resistance training within 6 months; 11 females) randomly performed exercise to failure (4× sets to failure, 20% 1RM, 1 min rest between sets) in each of three conditions: SC-BFR (using the Delfi Personalized Tourniquet Device inflated to 60% limb occlusion pressure), MC-BFR (using the B Strong Cuffs inflated to 300 mmHg according to manufacturer recommendations), and N-BFR (no BFR control).

Results

SC-BFR blunted post-exercise increases in carotid-femoral pulse wave velocity (p = 0.328) (+3.3%) whereas the other conditions showed elevations (MC-BFR +11.8% [p = 0.041], N-BFR +9.3% [p = 0.012]). Discomfort was lower in N-BFR compared to SC-BFR (p < 0.001) and MC-BFR (p = 0.035) but all displayed similar exertion (p = 0.176). Median total repetitions achieved were significantly less in SC-BFR (57 [25-75th percentile: 47-65) than MC-BFR (76 [63-91] (p = 0.043) and N-BFR [106 (97-148)] p = 0.005). Per set repetition volumes were similar on set 1 between SC-BFR (p < 0.001) and MC-BFR (p = 0.001) and were lower than N-BFR (p ≤ 0.001) whereas in sets 2-4, MC-BFR performed similar number of repetitions as N-BFR (p = 0.984-1.000).

Conclusion

Bladder design of a BFR cuff has an impact on the acute responses to exercise if applied according to recommended application guidelines, as SC-BFR impacts performance to a greater degree and mitigates post-exercise arterial stiffness responses compared to MC-BFR and N-BFR while both BFR conditions display greater levels of discomfort compared to N-BFR.

Clinical Trial Registration

NCT06276673.

Comparing adaptations from blood flow restriction exercise training using regulated or unregulated pressure systems: A systematic review and meta-analysis

OBJECTIVE

No study has examined outcomes derived from blood flow restriction exercise training interventions using regulated compared with unregulated blood flow restriction pressure systems. Therefore, we used a systematic review and meta-analyses to compare the chronic adaptations to blood flow restriction exercise training achieved with regulated and unregulated blood flow restriction pressure systems.

DATA SOURCES

The electronic database search included using the tool EBSCOhost and other online database search engines. The search included Medline, SPORTDiscus, CINAHL, Embase and SpringerLink.

METHODS

Included studies utilised chronic blood flow restriction exercise training interventions greater than two weeks duration, where blood flow restriction was applied using a regulated or unregulated blood flow restriction pressure system, and where outcome measures such as muscle strength, muscle size or physical function were measured both pre- and post-training. Studies included in the meta-analyses used an equivalent non-blood flow restriction exercise comparison group.

RESULTS

Eighty-one studies were included in the systematic review. Data showed that regulated (n = 47) and unregulated (n = 34) blood flow restriction pressure systems yield similar training adaptations for all outcome measures post-intervention. For muscle strength and muscle size, this was reaffirmed in the included meta-analyses.

CONCLUSION

This review indicates that practitioners may achieve comparable training adaptations with blood flow restriction exercise training using either regulated or unregulated blood flow restriction pressure systems. Therefore, additional factors such as device quality, participant comfort and safety, cost and convenience are important factors to consider when deciding on appropriate equipment to use when prescribing blood flow restriction exercise training.

The impact of acute blood-flow-restriction resistance exercise on somatosensory-evoked potentials in healthy adults

Blood-flow-restriction exercise (BFREX) is an emerging method to stimulate hypertrophy and strength without the need for high training loads. However, the impact of BFREX concerning somatosensory processing remains elusive. Here, we aimed to investigate the acute effects of BFREX on somatosensory processing in healthy adults using somatosensory-evoked potentials (SEPs). Twelve healthy adults (23.0 ± 3.2 years of age) participated in a randomized crossover experiment, consisting of three experimental conditions: application of blood-flow restriction without resistance exercise (BFR), resistance exercise for multiple sets with blood-flow restriction (BFREX) and traditional resistance exercise (unilateral biceps curls) for multiple sets without BFR (EX). SEP measurements were recorded bilaterally before, during and after each condition. SEP amplitudes were largely unaffected during various occlusive conditions. Nonetheless, our findings demonstrate a significant decrease in N9 latencies for condition EX compared with BFR, specifically in the exercised limb (mean difference = -0.26 ms, SE = 0.06 ms, P = 0.002, d = -0.335). This study provides evidence on the lack of impact of BFREX within the somatosensory domain, according to current guidelines. As an alternative method to traditional high-load resistance exercise, BFREX might offer a considerable upside for rehabilitative settings by reducing strain on the musculoskeletal system.

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.

An examination of acute physiological and perceptual responses following blood flow restriction exercise using a traditional research device or novel, automated system

Objective. To compare the acute physiological and perceptual responses to blood flow restriction (BFR) exercise using a traditional research device or novel, automated system.Methods. Forty-four resistance trained individuals performed four sets of unilateral elbow flexion exercise (30% one-repetition maximum) to volitional failure using two distinct restrictive devices [SmartCuffs PRO BFR Model (SMARTCUFF), Hokanson E20 Rapid Inflation device (HOKANSON)] and with two levels of BFR [40% limb occlusion pressure (LOP), 80% LOP]. Blood pressure (BP), muscle thickness (MT), and isometric strength (ISO) were assessed prior to and following exercise. Perceptual responses [ratings of perceived exertion (RPE), discomfort] were assessed prior to exercise and following each exercise set.Main results. Data are displayed as means (SD). Immediately following exercise with 40% LOP, there were no statistical differences between devices for BP, MT, and ISO. However, only following Set 1 of exercise, RPE was greater with SMARTCUFF compared to HOKANSON (p< 0.05). In addition, only following Set 2 of exercise, discomfort was greater with HOKANSON compared to SMARTCUFF (p< 0.001). Immediately following exercise with 80% LOP, there were no statistical differences between devices for BP, MT, and ISO. However, only following Set 4 of exercise, RPE was greater with HOKANSON compared to SMARTCUFF (p< 0.05). In addition, following all exercise sets, discomfort was greater with HOKANSON compared to SMARTCUFF (p< 0.001). For repetitions completed with 40% LOP there were no statistical differences between SMARTCUFF and HOKANSON across any exercise sets. For repetitions completed with 80% LOP there were no statistical differences between SMARTCUFF and HOKANSON across Set 1 of exercise (p= 0.34), however, for Sets 2-4 of exercise, significantly greater number of repetitions were completed during SMARTCUFF than HOKANSON.Significance. The present study provides valuable insight into the efficacy of a novel, automated BFR system (SMARTCUFF) eliciting comparable acute physiological responses to BFR exercise and in some cases favorable perceptual responses when compared to a traditional research device (HOKANSON).

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.

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.

Effects of Minimal-Equipment Resistance Training and Blood Flow Restriction on Military-Relevant Performance Outcomes

ABSTRACT

Cintineo, HP, Chandler, AJ, Mastrofini, GF, Lints, BS, McFadden, BA, and Arent, SM. Effects of minimal-equipment resistance training and blood flow restriction on military-relevant performance outcomes. J Strength Cond Res 38(1): 55-65, 2024-This study compared minimal-equipment resistance training (RT) with and without blood flow restriction (BFR) to traditional-equipment RT on performance and body composition changes over 6 weeks. Reserve officers' training corps cadets and midshipmen (N = 54, 40.7% female) were randomized into traditional-equipment RT (TRAD), minimal-equipment RT (MIN), or minimal-equipment RT with BFR (MIN + BFR). Performance and body composition were assessed pretraining and post-training, and measures of intensity and workload were evaluated throughout. Performance assessments included the army combat fitness test (ACFT), countermovement vertical jump, 3RM bench press, and V̇O2max; body composition measures included body fat percentage, fat-free mass, and muscle and tendon thickness. All groups trained 4 days per week after a full-body routine. Data were analyzed by mixed-effects models (α = 0.05). Group-by-time interactions for 3RM deadlift and 3RM bench press (p < 0.004) showed larger improvements for TRAD compared with MIN and MIN + BFR. Time main effects for all other performance variables, body fat percentage, fat-free mass, and muscle thickness (p ≤ 0.035) indicated improvements in all groups. A group-by-time interaction for blood lactate (p < 0.001) and group main effects for heart rate (p < 0.001) and workload variables (p < 0.008) indicated higher intensity and workload for MIN and MIN + BFR compared with TRAD. A sex-by-time interaction for 3RM deadlift (p = 0.008) and sex-by-group-by-time interaction for 3RM bench press (p = 0.018) were also found. Minimal-equipment RT improved performance and body composition, although strength improvements were greater with traditional equipment. Minimal-equipment RT and minimal-equipment RT with BFR exhibited higher exertion levels than TRAD, although adaptations were similar. Overall, individuals can improve performance and body composition using portable, field-expedient RT equipment.

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.

No Differences in Exercise Performance, Perceptual Response, or Safety Were Observed Among 3 Blood Flow Restriction Devices

Purpose

To compare 3 separate blood flow restriction (BFR) systems in their capacity to reduce repetitions to failure, impact perceptual responses, and cause adverse events during a low-load free-flow exercise.

Methods

The study included healthy subjects aged 18 years or older who presented to an ambulatory-care sports medicine clinic. On day 1, participants' demographic characteristics and anthropomorphic measurements were recorded. Each participant performed dumbbell biceps curl repetitions to failure using 20% of his or her 1-repetition maximum weight with each arm. Participants were exposed to 3 different tourniquet systems for familiarization. On day 2, each participant's arm was randomized to a cuff system, and the participant performed 2 sets of biceps curl repetitions to failure with the cuff inflated. Repetitions to failure, rating of perceived effort (RPE), rating of perceived discomfort, and pulse oxygenation levels were recorded after each set. On day 3, participants completed a survey of their perceived delayed-onset muscle soreness.

Results

The final analysis was performed on 42 arms, with 14 limbs per system. The study population had a mean age of 28.7 ± 2.4 years and a mean body mass index of 24.9 ± 4.3. All 3 systems successfully reduced repetitions to failure compared with unrestricted low-load exercise from baseline to BFR set 1 and from baseline to BFR set 2. There were no significant between-group differences among BFR systems regarding the number of repetitions to failure performed at baseline versus BFR set 1 or BFR set 2. The Delfi Personalized Tourniquet System (PTS) cohort had the greatest reductions in repetitions to failure from BFR set 1 to BFR set 2 (P = .002) and reported the highest RPE after set 2 (P = .025).

Conclusions

The Delfi PTS, SmartCuffs Pro, and BStrong BFR systems were each safe and were able to significantly reduce repetitions to failure compared with a low-load free-flow condition when used in a BFR exercise protocol. The Delfi PTS system may produce a higher RPE with prolonged use in comparison to the other systems.

Level of Evidence

Level II, prospective cohort study.

Blood flow restriction training activates the muscle metaboreflex during low-intensity sustained exercise

Blood flow restriction training (BFRT) employs partial vascular occlusion of exercising muscle and has been shown to increase muscle performance while using reduced workload and training time. Numerous studies have demonstrated that BFRT increases muscle hypertrophy, mitochondrial function, and beneficial vascular adaptations. However, changes in cardiovascular hemodynamics during the exercise protocol remain unknown, as most studies measured blood pressure before the onset and after the cessation of exercise. With reduced perfusion to the exercising muscle during BFRT, the resultant accumulation of metabolites within the ischemic muscle could potentially trigger a large reflex increase in blood pressure, termed the muscle metaboreflex. At low workloads, this pressor response occurs primarily via increases in cardiac output. However, when increases in cardiac output are limited (e.g., heart failure or during severe exercise), the reflex shifts to peripheral vasoconstriction as the primary mechanism to increase blood pressure, potentially increasing the risk of a cardiovascular event. Using our chronically instrumented conscious canine model, we utilized a 60% reduction in femoral blood pressure applied to the hindlimbs during steady-state treadmill exercise (3.2 km/h) to reproduce the ischemic environment observed during BFRT. We observed significant increases in heart rate (+19 ± 3 beats/min), stroke volume (+2.52 ± 1.2 mL), cardiac output (+1.21 ± 0.2 L/min), mean arterial pressure (+18.2 ± 2.4 mmHg), stroke work (+1.93 ± 0.2 L/mmHg), and nonischemic vascular conductance (+3.62 ± 1.7 mL/mmHg), indicating activation of the muscle metaboreflex.NEW & NOTEWORTHY Blood flow restriction training (BFRT) increases muscle mass, strength, and endurance. There has been minimal consideration of the reflex cardiovascular responses that could be elicited during BFRT sessions. We showed that during low-intensity exercise BFRT may trigger large reflex increases in blood pressure and sympathetic activity due to muscle metaboreflex activation. Thus, we urge caution when employing BFRT, especially in patients in whom exaggerated cardiovascular responses may occur that could cause sudden, adverse cardiovascular events.

Impact of Blood-Flow-Restricted Training on Arterial Functions and Angiogenesis-A Systematic Review with Meta-Analysis

Despite growing evidence of the significant influence of blood-flow-restricted (BFR) training on different body functions, its impact on the vascular system, especially the arteries, is controversial. Therefore, the objective of our study was to analyze how BFR exercise, compared to other types of exercise without the restriction of blood flow, influences arterial functions and angiogenesis in adults. Studies comparing the effect of BFR versus non-BFR training on arterial parameters were divided into three categories: endothelial function, angiogenesis, and other vasculature functions. The search was based on Cochrane Library, PubMed®, and Embase, and 38 studies were included. The meta-analysis revealed a more significant improvement in flow-mediated dilatation (FMD) (p = 0.002) and the production of the primary angiogenesis biomarker vascular endothelial growth factor (VEGF) (p = 0.009) after BFR compared to non-BFR training (p = 0.002). The analysis of the pulse wave velocity, ankle-brachial index, systolic blood pressure, and heart rate did not show significant differences in changes between BFR and non-BFR training. The other parameters examined did not have sufficient data to be included in the meta-analysis. The results obtained present trends that suggest significant impacts of BFR training on endothelial functions and angiogenesis. There is still a lack of multicenter randomized clinical trials including many participants, and such studies are necessary to confirm the advantage of BFR over non-BFR activity.

Low-Intensity Blood Flow Restriction Exercises Modulate Pain Sensitivity in Healthy Adults: A Systematic Review

Low-intensity exercise with blood flow restriction (LIE-BFR) has been proposed as an effective intervention to induce hypoalgesia in both healthy individuals and patients with knee pain. Nevertheless, there is no systematic review reporting the effect of this method on pain threshold. We aimed to evaluate the following: (i) the effect of LIE-BFR on pain threshold compared to other interventions in patients or healthy individuals; and (ii) how different types of applications may influence hypoalgesic response. We included randomized controlled trials assessing the effectiveness of LIE-BFR alone or as an additive intervention compared with controls or other interventions. Pain threshold was the outcome measure. Methodological quality was assessed using the PEDro score. Six studies with 189 healthy adults were included. Five studies were rated with 'moderate' and 'high' methodological quality. Due to substantial clinical heterogeneity, quantitative synthesis could not be performed. All studies used pressure pain thresholds (PPTs) to assess pain sensitivity. LIE-BFR resulted in significant increases in PPTs compared to conventional exercise at local and remote sites 5 min post-intervention. Higher-pressure BFR results in greater exercise-induced hypoalgesia compared to lower pressure, while exercise to failure produces a similar reduction in pain sensitivity with or without BFR. Based on our findings, LIE-BFR can be an effective intervention to increase pain threshold; however, the effect depends on the exercise methodology. Further research is necessary to investigate the effectiveness of this method in reducing pain sensitivity in patients with pain symptomatology.

Effects of blood flow restriction on spine postural control using a robotic platform: A pilot randomized cross-over study

BACKGROUND

Blood flow restriction (BFR) training improves muscle strength and functional outcomes, but the proprioceptive implications of this technique in the rehabilitation field are still unknown.

OBJECTIVE

The present study aimed at assessing the effects of BFR in terms of stabilometric and balance performance.

METHODS

In this pilot randomized cross-over study, healthy young adults were included and randomly assigned to Groups A and B. Both groups underwent a postural assessment with and without wearing a BFR device. Study participants of Group A underwent postural baseline assessment wearing BFR and then removed BFR for further evaluations, whereas subjects in Group B performed the baseline assessment without BFR and then with BFR. Stabilometric and balance performance were assessed by the robotic platform Hunova, the Balance Error Scoring System (BESS), the self-reported perceived balance (7-point Likert scale), and discomfort self-rated assessment. Moreover, the safety profile was recorded.

RESULTS

Fourteen subjects were included and randomly assigned to Group A (n: 7) and Group B (n: 7). Significant differences were shown in balance tests in static conditions performed on the Hunova robot platform in terms of average distance RMS (root-mean-square) with open eyes (OE), anteroposterior (AP) trunk oscillation range with OE, mediolateral (ML) average speed of oscillation with OE, and total excursion AP range with closed eyes (CE) (BFR: 3.44 ± 1.06; without BFR: 2.75 ± 0.72; p= 0.041). Moreover, elastic balance test showed differences in Romberg index (BFR: 0.16 ±0.16; without BFR: 0.09 ± 0.07; p= 0.047). No adverse events were reported.

CONCLUSION

Taken together, our data showed that BFR affects balance performance of healthy subjects. Further studies are needed to better characterize the possible role of BFR treatment in the context of a specific rehabilitation protocol.

Beneath the cuff: Often overlooked and under-reported blood flow restriction device features and their potential impact on practice-A review of the current state of the research

Training with blood flow restriction (BFR) has been shown to be a useful technique to improve muscle hypertrophy, muscle strength and a host of other physiological benefits in both healthy and clinical populations using low intensities [20%-30% 1-repetition maximum (1RM) or <50% maximum oxygen uptake (VO_2max)]. However, as BFR training is gaining popularity in both practice and research, there is a lack of awareness for potentially important design characteristics and features associated with BFR cuff application that may impact the acute and longitudinal responses to training as well as the safety profile of BFR exercise. While cuff width and cuff material have been somewhat addressed in the literature, other cuff design and features have received less attention. This manuscript highlights additional cuff design and features and hypothesizes on their potential to impact the response and safety profile of BFR. Features including the presence of autoregulation during exercise, the type of bladder system used, the shape of the cuff, the set pressure versus the interface pressure, and the bladder length will be addressed as these variables have the potential to alter the responses to BFR training. As more devices enter the marketplace for consumer purchase, investigations specifically looking at their impact is warranted. We propose numerous avenues for future research to help shape the practice of BFR that may ultimately enhance efficacy and safety using a variety of BFR technologies.

Exercised-Induced Hypoalgesia following An Elbow Flexion Low-Load Resistance Exercise with Blood Flow Restriction: A Sham-Controlled Randomized Trial in Healthy Adults

We aimed to evaluate the hypoalgesic effect of an elbow flexion low-load resistance exercise with blood flow restriction (LLRE-BFR) when compared to high-load resistance exercise (HLRE) with sham-BFR in healthy individuals. Forty healthy young adults (17 women), with a mean age ± SD: 26.6 ± 6.8 years, and mean body mass index ± SD: 23.6 ± 2.7 were randomly assigned to either an LLRE-BFR (30% 1 repetition maximum, RM) or an HLRE with sham-BFR group (70% of 1 RM). Blood pressure and pressure pain thresholds (PPTs) were measured pre- and post-exercise intervention. The rating of perceived exertion (RPE) was recorded after each set. There were non-significant between-group changes in PPT at the dominant biceps (-0.61, 95%CI: -1.92 to 0.68) with statistically significant reductions between pre- and post-exercise in LLRE-BFR (effect size, d = 0.88) and HLRE-BFR (effect size, d = 0.52). No within- or between-group differences were recorded in PPT at non-exercising sites of measurement. No mediating effects of changes in blood pressure or RPE on the changes in pressure pain threshold were observed. LLRE-BFR produced a similar hypoalgesic effect locally compared to HLRE and can be used as an alternative intervention to decrease pain sensitivity when HLRE is contraindicated or should be avoided.

Low-Load Resistance Training With Blood Flow Restriction Is Effective for Managing Lateral Elbow Tendinopathy: A Randomized, Sham-Controlled Trial

OBJECTIVE: To evaluate the effect of low-load resistance training with blood flow restriction (LLRT-BFR) when compared to LLRT with sham-BFR in patients with lateral elbow tendinopathy (LET). DESIGN: Randomized controlled trial. METHODS: Forty-six patients with LET were randomly assigned to a LLRT-BFR or a LLRT with sham-BFR treatment group. All patients received soft tissue massage, supervised exercises with BFR or sham intervention (twice a week for 6 weeks), advice, and a home exercise program. The primary outcome measures were pain intensity, patient-rated tennis elbow evaluation (PRTEE) score, pain-free grip strength, and global rating of change, measured at baseline, 6 weeks, and 12 weeks. Between-group differences were evaluated using mixed-effects models with participant-specific random effects for continuous data. Global rating of change was analyzed using logistic regression. RESULTS: Statistically significant between-group differences were found in favor of LLRT-BFR compared to LLRT with sham-BFR in pain intensity at 12-week follow-up (-1.54, 95% CI: -2.89 to -0.18; P = .026), pain-free grip strength ratio at 6-week follow-up (0.20, 95% CI: 0.06 to 0.34; P = .005), and PRTEE at 6- and 12-week follow-up (-11.92, 95% CI: -20.26 to -3.59; P = .006, and -15.23, 95% CI: -23.57 to -6.9; P<.001, respectively). At 6- and 12-weeks, patients in the LLRT-BFR group had greater odds of reporting complete recovery or significant improvement (OR = 6.0, OR = 4.09, respectively). CONCLUSION: Low-load resistance training with blood flow restriction produced significantly better results compared to the LLRT with sham-BFR for all primary outcomes. Considering the clinically significant between-group improvement in function (>11 points in PRTEE) and the better success rates in the LLRT-BFR group, this intervention may improve recovery in LET. J Orthop Sports Phys Ther 2022;52(12):803-825. Epub: 14 September 2022. doi:10.2519/jospt.2022.11211.

Blood Flow Restriction Therapy: An Evidence-Based Approach to Postoperative Rehabilitation

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Blood flow restriction therapy (BFRT) involves the application of a pneumatic tourniquet cuff to the proximal portion of the arm or leg. This restricts arterial blood flow while occluding venous return, which creates a hypoxic environment that induces many physiologic adaptations.

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BFRT is especially useful in postoperative rehabilitation because it produces muscular hypertrophy and strength gains without the need for heavy-load exercises that are contraindicated after surgery.

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Low-load resistance training with BFRT may be preferable to low-load or high-load training alone because it leads to comparable increases in strength and hypertrophy, without inducing muscular edema or increasing pain.

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

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

Low-Intensity Resistance Exercise Combined With Blood Flow Restriction is More Conducive to Regulate Blood Pressure and Autonomic Nervous System in Hypertension Patients-Compared With High-Intensity and Low-Intensity Resistance Exercise

Background: The effect of resistance exercise on the autonomic nervous system of patients with hypertension has not been identified.

Objective: To explore a suitable resistance training method for hypertension patients to regulate blood pressure (BP) and autonomic nervous system function.

Method: Forty-five hypertension patients aged between 55 and 70 years were randomly equally divided into three groups: the high-intensity resistance exercise (HE) group, the low-intensity resistance exercise combined with blood flow restriction (LE-BFR) group, and the low-intensity resistance exercise (LE) group. All patients performed quadriceps femoris resistance exercise. The exercise intensity of HE, LE-BFR and LE group was 65, 30 and 30% of one repetition maximum (1RM), respectively. The LE-BFR group used pressure cuffs to provide 130% of systolic pressure to the patient’s thighs during resistance exercise. The training program was 20 times/min/set with a 1-min break after each set, and was conducted five sets/day and 3 days/week, lasting for 12 weeks. The heart rate (HR), BP, root-mean-square of difference-value of adjacent RR intervals (RMSSD), low frequency (LF) and high frequency (HF) were evaluated before and after the first training and the last training.

Result: Significant differences in HR were observed in both recovery states after the first and last training (p < 0.01). After 12 weeks of training, the recovery speed of HR in the LE-BFR group increased significantly (p < 0.01). The systolic blood pressures in the HE and LE-BFR group were significantly reduced (p < 0.05 and p < 0.01), and the differences among groups were significant (p < 0.01). In the last recovery state, the RMSSD of the LE group was significantly lower than that in the first recovery state (p < 0.01). The LF/HF ratios of the HE and LE groups in the resting and recovery states were increased significantly (all p < 0.01). LF/HF ratios in the LE-BFR group in the resting and recovery state were decreased significantly (both p < 0.01).

Conclusion: Compared to HE and LE, LE-BFR could effectively decrease systolic pressure and regulate the autonomic nervous system function in hypertension patients.

Physiological Adaptations to High-Intensity Interval Training Combined with Blood Flow Restriction in Masters Road Cyclists

PURPOSE

High-intensity interval training (HIIT) and blood flow restriction (BFR) training have been used to enhance athletic performance and cardiovascular health. Combining these training modalities might be an effective training modality for masters athletes who seek to enhance athletic performance and to reduce cardiovascular risks.

METHODS

Fifty masters road cyclists age 35-49 yr were randomly assigned to the continuous exercise training (n = 16), continuous plus HIIT (n = 17), and continuous plus BFR training combined with HIIT (BFRIT; n = 17) for 12 wk. Both HIIT and BFRIT were performed on a cycle ergometer twice a week.

RESULTS

Maximal oxygen consumption (V̇O2max) increased in the HIIT and BFRIT groups (P < 0.05). This was accompanied by significant improvements in maximal cardiac output and stroke volume (P < 0.05). Forty-kilometer time trial performance improved in all three groups (P < 0.05). Peak power output increased in both HIIT and BFRIT groups (P < 0.05). Flow-mediated dilation in both brachial and popliteal arteries increased in all three groups (all P < 0.05). There were no significant changes in carotid intima-media thickness and arterial stiffness in any of the groups. Total lean mass, muscle cross-sectional area and thickness in rectus femoris and vastus lateralis, and peak torque of isokinetic knee extension increased only in the BFRIT group (all P < 0.05). Tissue saturation index decreased only in the BFRIT group (P < 0.05). Changes in 40-km time trial performance were associated with corresponding changes in V̇O2max (r = -0.312, P = 0.029) and peak isokinetic extensor torque (r = -0.432, P = 0.002).

CONCLUSIONS

Including HIIT particularly with BFR in the routine continuous training may be more effective in enhancing performance and physiological functions in masters road cyclists.

Low load strength training, associated with or without blood flow restriction increased NO production and decreased production of reactive oxygen species in the in rats aorta

Studies have shown that strength training (ST) with blood flow restriction (BFR) in which low load is used (20-50% of 1 maximum voluntary contraction - MVC) can produce positive adaptations similar to ST with loads equal to or greater than 70% 1 MVC. Furthermore, recent studies have investigated the effects of STBFR on muscle adaptations, but few studies investigated the effects of STBFR on vascular function. This study aimed to evaluate the effects of the STBFR program on the vascular reactivity of the abdominal aorta of Wistar rats with femoral arteriovenous blood flow restriction. Male rats were divided into four groups: sedentary sham (S/S), sedentary with blood flow restriction (S/BFR), trained sham (T/S), and trained with blood flow restriction (T/BFR). The animals in the S/BFR and T/BFR groups underwent surgery to BFR in the femoral artery and vein. After one week, the trained groups started the ST which consisted of climbing ladder, six sets of 10 repetitions with 50% of 1 MVC assessed by maximum loaded weight (MLW) carried out for four weeks. Concentration-response curves to Acetylcholine (ACh: 10 nM - 100 μM) and Phenylephrine (PHE: 1 nM - 30 μM) were performed in aortic rings with intact endothelium. The production of nitric oxide (NO) and reactive oxygen species (ROS) in situ and the vascular remodeling marker (MMP-2) were also measured. The ST increased the strength of the T/S and T/BFR groups in MLW tests. The S/BFR group showed a 22% reduction in relaxation to acetylcholine, but exercise prevented this reduction in the T/BFR group. In animals without BFR, ST did not alter the response to acetylcholine. An increase in NO production was seen in T/S and T/BFR showed a reduction in ROS production (62% and 40%, respectively). In conclusion low load ST with BFR promotes similar vascular function responses to ST without BFR. Low load ST with and without BFR is interventions that can improve performance with similar magnitudes. Both training methods could have some benefits for vascular health due to NO production in the aorta increased in the T/S group and decreased production of reactive oxygen species in the T/BFR group.

Effects of resistance training on endothelial function: A systematic review and meta-analysis

BACKGROUND AND AIMS

The effects of resistance training on flow-mediated dilation (FMD), which has been the gold standard non-invasive assessment of endothelial function and is associated with the risk of cardiovascular events, are not well known. We conducted a systematic review to analyze the effects of resistance training on FMD.

METHODS

We searched Pubmed, Embase, CINAHL, SPORTDiscuss, Scopus, Web of Science and PEDro databases for studies that met the following criteria: (a) randomized controlled trials of resistance exercise with a comparative non-exercise group or contralateral untrained limb in adults and/or elderly; (b) studies that measured post-occlusion brachial artery FMD by ultrasonography, before and after intervention. Mean differences (MDs) with 95 % confidence interval (95 % CI) were calculated using an inverse variance method with a random effects model.

RESULTS

Twenty-three studies were included in the meta-analysis (n = 785 participants; 53 % females). Resistance training on FMD responses showed a favorable result for the resistance training group (n = 366) compared to the control group (n = 358) (MD 2.39, 95%CI 1.65, 3.14; p<0.00001). Subgroup analysis indicated favorable results for the dynamic resistance training (n = 545; MD 2.12, 95 % CI 1.26, 2.98; p<0.00001) and isometric handgrip training (n = 179; MD 3.32, 95 % CI 1.68, 4.96; p<0.0001) compared to the control group. The effect of resistance training on FMD responses was also favorable regardless of the condition of the participants (Healthy [n = 261]: MD 2.11, 95 % CI 1.04, 3.18; p<0.0001; Cardiovascular disease [n = 310]: MD 2.89, 95 % CI 0.88, 4.90; p = 0.005; metabolic disease [n = 153]: MD 2.40, 95 % CI 1.59, 3.21; p<0.00001).

CONCLUSIONS

Resistance training improves FMD in healthy individuals and patients with cardiovascular and metabolic diseases.

Blood Flow Restriction Training: To Adjust or Not Adjust the Cuff Pressure Over an Intervention Period?

Blood flow restriction (BFR) training combines exercise and partial reduction of muscular blood flow using a pressured cuff. BFR training has been used to increase strength and muscle mass in healthy and clinical populations. A major methodological concern of BFR training is blood flow restriction pressure (BFRP) delivered during an exercise bout. Although some studies increase BFRP throughout a training intervention, it is unclear whether BFRP adjustments are pivotal to maintain an adequate BFR during a training period. While neuromuscular adaptations induced by BFR are widely studied, cardiovascular changes throughout training intervention with BFR and their possible relationship with BFRP are less understood. This study aimed to discuss the need for BFRP adjustment based on cardiovascular outcomes and provide directions for future researches. We conducted a literature review and analyzed 29 studies investigating cardiovascular adaptations following BFR training. Participants in the studies were healthy, middle-aged adults, older adults and clinical patients. Cuff pressure, when adjusted, was increased during the training period. However, cardiovascular outcomes did not provide a plausible rationale for cuff pressure increase. In contrast, avoiding increments in cuff pressure may minimize discomfort, pain and risks associated with BFR interventions, particularly in clinical populations. Given that cardiovascular adaptations induced by BFR training are conflicting, it is challenging to indicate whether increases or decreases in BFRP are needed. Based on the available evidence, we suggest that future studies investigate if maintaining or decreasing cuff pressure makes BFR training safer and/or more comfortable with similar physiological adaptation.