Blood Flow Restriction Resistance Training Research Articles

Effects of Low-Load Blood-Flow Restricted Resistance Training on Functional Capacity and Patient-Reported Outcome in a Young Male Suffering From Reactive Arthritis.

Introduction: Reactive arthritis (ReA) is a chronic inflammatory disease usually caused by a preceding gastrointestinal or genitourinary bacterial infection. ReA usually occurs in the lower limbs causing joint pain and joint swelling. Physiotherapy-led exercise is recommended to prevent muscle atrophy. The purpose of this case report is to describe the outcome after 12 weeks of low-load blood flow restricted resistance training (BFR-RT) as a rehabilitation method for a young male suffering from ReA.Methods and materials: A 17-year-old male suffered from ReA in the both knee joints and the left hip joint. 36 months after the incident, he suffered from another ReA incident in his right knee. Non-steroid anti-inflammatory drugs and a new arthrocentesis added with corticosteroid injection was unsuccessful in treating the ReA. The patient performed 12 weeks of BFR-RT on the right lower limb with a low amount of supervision after the first week of training. Assessment of unilateral 30-sec chair stand test (u30-sec CST), low-thigh circumference above apex patella, The Knee Injury and Osteoarthritis Outcome Score (KOOS), The Forgotten Knee Joint Score (FJS), and Numeric Ranking Scale for pain (NRS) was performed at baseline and after 3,6,9, and 12 weeks of BFR-RT.Results: The patient completed all planned exercise sessions. u30-sec CST improved with 7 repetitions (reps) on the right limb and 5 reps on the left leg. Low-thigh circumference decreased 1.1 cm on the right leg and 1.0 on the left leg. KOOS symptoms, ADL, quality of life and FJS demonstrated a clinically relevant change on 10, 14 and 23 points.Conclusion: The present case study indicates that even with low amounts of supervision BFR-RT could increase functional performance, reduce knee joint swelling and improve key patient-reported outcome.

Effects of blood-flow restricted resistance training on mechanical muscle function and thigh lean mass in sIBM patients.

Sporadic inclusion body myositis (sIBM) is an idiopathic inflammatory muscle disease associated with skeletal muscle inflammation and a parallel progressive decline in muscle strength and physical function. Eventually, most sIBM patients require use of wheelchair after about 10years of diagnosis and assistance to perform activities of daily living. This study presents data from a randomized controlled intervention trial (NCT02317094) that examined the effect of 12weeks low-load blood-flow restricted (BFR) resistance training on maximal muscle strength, power, rate of force development (RFD), thigh lean mass (TLM), and voluntary muscle activation (VA) in sIBM patients. A time-by-group interaction in knee extensor strength was observed in the stronger leg (p≤0.033) but not the weaker leg. Within-group changes were observed with BFR training (BFR) manifested by increased knee extensor strength in the strongest leg (+13.7%, p=0.049), whereas non-exercising patients (CON) showed reduced knee extensor strength (-7.7%, p=0.018). Maximal leg extensor power obtained for the stronger leg remained unchanged following BFR training (+9.5%, p=0.37) while decreasing in CON (-11.1%, p=0.05). No changes in TLM were observed. VA declined post-training (p=0.037) in both BFR (-6.3% points) and CON (-7.5% points). The present data indicate that BFR resistance training can attenuate the rate of decline in mechanical muscle function typically experienced by sIBM patients. The preservation of muscle mass and mechanical muscle function with BFR resistance training may be considered of high clinical importance in sIBM patients to countermeasure the disease-related decline in physical function.

Efficacy of low-load resistance training combined with blood flow restriction vs. high-load resistance training on sarcopenia among community-dwelling older Chinese people: study protocol for a 3-arm randomized controlled trial

BackgroundSarcopenia is accompanied by a decline in muscle mass, muscle strength, and muscle function. Resistance training is the most potential training method for the prevention and treatment of sarcopenia. However, the conventional high-load resistance training (CRT) recommended by the American College of Sports Medicine is a challenge for older people with sarcopenia. As a novel training method, low-load resistance training combined with blood flow restriction (LRT-BFR) may elicit similar muscle mass and muscle strength gains as CRT but with less effort. The objectives of this study are to assess and compare the efficacy and safety of 12-week LRT-BFR and CRT on muscle strength, muscle performance, body composition, pulmonary function, blood biomarkers, CVD risk factors, and quality of life in community-dwelling older Chinese people with sarcopenia.MethodThis is a 12-week, assessor-blinded, 3-arm randomized controlled trial with a non-exercise control group. Community-dwelling people over 65 years will be screened for sarcopenia according to the diagnostic criteria of the Asian Working Group for Sarcopenia (AWGS). Fifty-one subjects will be randomized into a LRT-BFR group (n = 17), a CRT group (n = 17), and a no-strength training control group (n = 17). The primary outcome is lower limb muscle strength. The secondary outcomes are body composition, upper limb muscle strength, pulmonary function, blood biomarkers, CVD risk factors, and quality of life. Post-intervention follow-up will be performed for 12 weeks. These indicators will be assessed at baseline (0 week), after the 12-week intervention (12 weeks), and at follow-up (24 weeks). The adverse events will also be reported. Data will be analyzed for all participants in an intent-to-treat plan.DiscussionThis study is the first RCT that will systematically measure and compare the efficacy and safety of LRT-BFR and CRT in older people with sarcopenia on muscle strength, body composition, pulmonary function, blood biomarkers (inflammatory biomarkers, hormone, and growth factors), CVD risk factors, and quality of life. This study can provide an efficient and safe method to prevent the progression of sarcopenia in older people.Trial registrationChinese Clinical Trial Registry ChiCTR2100042803. Registered on 28 January 2021.

Similar Morphological and Functional Training Adaptations Occur Between Continuous and Intermittent Blood Flow Restriction.

Davids, CJ, Raastad, T, James, L, Gajanand, T, Smith, E, Connick, M, McGorm, H, Keating, S, Coombes, JS, Peake, JM, and Roberts, LA. Similar morphological and functional training adaptations occur between continuous and intermittent blood flow restriction. J Strength Cond Res 35(7): 1784-1793, 2021-The aim of the study was to compare skeletal muscle morphological and functional outcomes after low-load resistance training using 2 differing blood flow restriction (BFR) protocols. Recreationally active men and women (n = 42 [f = 21], 24.4 ± 4.4 years) completed 21 sessions over 7 weeks of load-matched and volume-matched low-load resistance training (30% 1 repetition maximum [1RM]) with either (a) no BFR (CON), (b) continuous BFR (BFR-C, 60% arterial occlusion pressure [AOP]), or (c) intermittent BFR (BFR-I, 60% AOP). Muscle mass was assessed using peripheral quantitative computed tomography before and after training. Muscular strength, endurance, and power were determined before and after training by assessing isokinetic dynamometry, 1RM, and jump performance. Ratings of pain and effort were taken in the first and final training session. An alpha level of p < 0.05 was used to determine significance. There were no between-group differences for any of the morphological or functional variables. The muscle cross sectional area (CSA) increased pre-post training (p = 0.009; CON: 1.6%, BFR-C: 1.1%, BFR-I: 2.2%). Maximal isometric strength increased pre-post training (p < 0.001; CON: 9.6%, BFR-C: 14.3%, BFR-I: 19.3%). Total work performed during an isokinetic endurance task increased pre-post training (p < 0.001, CON: 3.6%, BFR-C: 9.6%, BFR-I: 11.3%). Perceptions of pain (p = 0.026) and effort (p = 0.033) during exercise were higher with BFR-C; however, these reduced with training (p = 0.005-0.034). Overall, these data suggest that when 30% 1RM loads are used with a frequency of 3 times per week, the addition of BFR does not confer superior morphological or functional adaptations in recreationally active individuals. Furthermore, the additional metabolic stress that is proposed to occur with a continuous BFR protocol does not seem to translate into proportionally greater training adaptations. The current findings promote the use of both intermittent BFR and low-load resistance training without BFR as suitable alternative training methods to continuous BFR. These approaches may be practically applicable for those less tolerable to pain and discomfort associated with ischemia during exercise.

Training response to 8 weeks of blood flow restricted training is not improved by preferentially altering tissue hypoxia or lactate accumulation when training to repetition failure

Despite compelling muscular structure and function changes resulting from blood flow restricted (BFR) resistance training, mechanisms of action remain poorly characterized. Alterations in tissue O2 saturation (TSI%) and metabolites are potential drivers of observed changes, but their relationships with degree of occlusion pressure are unclear. We examined local TSI% and blood lactate (BL) concentration during BFR training to failure using different occlusion pressures on strength, hypertrophy, and muscular endurance over an 8-week training period. Twenty participants (11M:9F) trained 3/wk for 8wk using high pressure (100% resting limb occlusion pressure, LOP, 20%1RM), moderate pressure (50% LOP, 20%1RM), or traditional resistance training (70%1RM). Strength, size, and muscular endurance were measured pre/post training. TSI% and BL were quantified during a training session. Despite overall increases, no group preferentially increased strength, hypertrophy, or muscular endurance (p>0.05). Neither TSI% nor BL concentration differed between groups (p>0.05). Moderate pressure resulted in greater accumulated deoxygenation stress (TSI%*time) (-6352±3081, -3939±1835, -2532±1349 au for moderate pressure, high pressure, and TRT, p=0.018). We demonstrate that BFR training to task-failure elicits similar strength, hypertrophy, and muscular endurance changes to traditional resistance training. Further, varied occlusion pressure does not impact these outcomes, nor elicit changes in TSI% or BL concentrations. Novelty Bullets • Training to task failure with low-load blood flow restriction elicits similar improvements to traditional resistance training, regardless of occlusion pressure. • During blood flow restriction, altering occlusion pressure does not proportionally impact tissue O2 saturation nor blood lactate concentrations.

The effectiveness of blood-flow restricted resistance training in the musculoskeletal rehabilitation of patients with lower limb disorders: A systematic review and meta-analysis

Objective: This meta-analysis aimed to evaluate the effectiveness of low-load Resistance Training (RT) with or without Blood Flow Restriction (BFR) compared with conventional RT on muscle strength in open and closed kinetic chains, muscle volume and pain in individuals with orthopaedic impairments. Data sources: Searches were conducted in the PubMed, Web of Science, Scopus and Cochrane databases, including the reference lists of randomised controlled trials (RCT’s) up to January 2021. Review method: An independent reviewer extracted study characteristics, orthopaedic indications, exercise data and outcome measures. The primary outcome was muscle strength of the lower limb. Secondary outcomes were muscle volume and pain. Study quality and reporting was assessed using the TESTEX scale. Results: A total of 10 RCTs with 386 subjects (39.2 ± 17.1 years) were included in the analysis to compare low-load RT with BFR and high or low-load RT without BFR. The meta-analysis showed no significant superior effects of low-load resistance training with BFR regarding leg muscle strength in open and closed kinetic chains, muscle volume or pain compared with high or low-load RT without BFR in subjects with lower limb impairments. Conclusion: Low-load RT with BFR leads to changes in muscle strength, muscle volume and pain in musculoskeletal rehabilitation that are comparable to conventional RT. This appears to be independent of strength testing in open or closed kinetic chains.

Effects of 5 Week Low-Intensity Blood Flow Restriction Resistance Exercise and Moderate-Intensity Resistance Exercise on Body Composition and Blood Lipids in Normal Weight Obese Women

PURPOSE:The primary objective of this study was to investigate and compare the effects of 5 weeks resistance training protocols (i.e., low-load blood flow restriction resistance training and moderate-load resistance training) especially on blood lipids, muscle strength, anaerobic power and body composition in young normal weight obese women.METHODS: Twenty-nine young normal weight obese women were randomly divided into three groups: blood flow restriction resistance training (BFR-RT, n=9), resistance training (RT, n=10) and non-training control (CON, n=10). BFR-RT group fitted a pneumatic cuff over the upper and lower extremities by using Kaatsu Nano equipment to apply the same pressures with each systolic blood pressure. The subjects in the BFR-RT group performed the training with 40% of 1RM and the RT group executed the resistance training with their 60-70% of 1RM. Both groups had performed the resistance training protocols twice per week for 5 weeks, and each training protocol consisted of bench press, barbell row, squat, and lunge.RESULTS:There were no changes in body weight, fat mass, BMI and %body fat in all groups after interventions for 5 weeks. However, the anaerobic power was significantly increased in both BFR-RT and RT groups compared to the CON group. Interestingly, only in the RT group, muscle mass and high-density lipoprotein cholesterol were significantly increased after the intervention.CONCLUSIONS: In conclusion, this study suggests that moderate-intensity RT is better than low-intensity BFR-RT to improve muscle mass and high-density lipoprotein cholesterol in young normal weight obese women.

Patterns of responses and time-course of changes in muscle size and strength during low-load blood flow restriction resistance training in women.

The purpose of this investigation was to examine the individual and composite patterns of responses and time-course of changes in muscle size, strength, and edema throughout a 4 week low-load blood flow restriction (LLBFR) resistance training intervention. Twenty recreationally active women (mean ± SD; 23 ± 3 years) participated in this investigation and were randomly assigned to 4 weeks (3/week) of LLBFR (n = 10) or control (n = 10) group. Resistance training consisted of 75 reciprocal isokinetic forearm flexion-extension muscle actions performed at 30% of peak torque. Strength and ultrasound-based assessments were determined at each training session. There were quadratic increases for composite muscle thickness (R2 = 0.998), concentric peak torque (R2 = 0.962), and maximal voluntary isometric contraction (MVIC) torque (R2 = 0.980) data for the LLBFR group. For muscle thickness, seven of ten subjects exceeded the minimal difference (MD) of 0.16cm during the very early phase (laboratory visits 1-7) of the intervention compared to three of ten subjects that exceeded MD for either concentric peak torque (3.7Nm) or MVIC (2.2Nm) during this same time period. There was a linear increase for composite echo intensity (r2 = 0.563) as a result of LLBFR resistance training, but eight of ten subjects never exceeded the MD of 14.2Au. These findings suggested that the increases in muscle thickness for the LLBFR group were not associated with edema and changes in echo intensity should be examined on a subject-by-subject basis. Furthermore, LLBFR forearm flexion-extension resistance training elicited real increases in muscle size during the very early phase of training that occurred prior to real increases in muscle strength.

The acute and early phase effects of blood flow restriction training on ratings of perceived exertion, performance fatigability, and muscular strength in women

BACKGROUND: Blood flow restriction (BFR) resistance training (RT) has garnered recent interest, but female-specific data remains scarce. OBJECTIVE: The purpose was to examine the effects of 2-wks of low-load concentric, isokinetic, reciprocal forearm flexion and extension training, with and without BFR on perceptual responses, performance fatigability, and muscular strength. METHODS: Twenty women were assigned to a BFRT or a non-BFRT group. Each group trained at 30% of concentric peak moment. Each session consisted of 75 concentric, isokinetic, reciprocal forearm flexion extension muscle actions. RPEs were recorded following each set. Pretest and posttest maximal voluntary isometric contraction (MVIC) force was measured, and percent decline was defined as performance fatigability. RESULTS: The RPE values (p&lt; 0.05) increased across sets. Strength (collapsed across muscle action) increased (p&lt; 0.05) from 0-wk (23.7 ± 3.2 Nm) to 2-wk (26.8 ± 2.7 Nm). Independent of group and muscle action, performance fatigability (p&lt; 0.05) increased from 0-wk (10.9 ± 5.0%) to 2-wk (14.1 ± 4.4%). CONCLUSIONS: 2-wks of low-load concentric, reciprocal forearm flexion and extension training resulted in similar training-induced changes in perceptual responses, performance fatigability, and muscular strength between BFRT and non-BFRT. These findings may reduce concerns of increased perceptual responses following BFRRT compared to non-BFRRT.

Myocellular Adaptations to Low-Load Blood Flow Restricted Resistance Training.

Low-load blood flow restricted resistance exercise (BFRRE) can stimulate whole-muscle growth and improve muscle function. However, limited knowledge exists on the effects at the myocellular level. We hypothesize that BFRRE has the ability to produce concurrent skeletal muscle myofibrillar, mitochondrial, and microvascular adaptations, thus offering an alternative strategy to counteract decay in skeletal muscle health and function in clinical populations.

Examination Of High-velocity Blood Flow Restricted Resistance Exercise Versus High-load Resistance Exercise

Muscle strength gains following blood flow restricted (BFR) resistance training are consistently lower than those observed after HL training and this may be due to differences in neuromuscular activation. Integrating high-velocity muscle contractions and BFR resistance exercise may increase neuromuscular activation. PURPOSE: To compare torque and neuromuscular activation before and after sessions of HL knee extension exercise and high-velocity BFR knee extension exercise in young and older adults. METHODS: Ten young males and females (20.3+1.5 years, 1.73+.06 m, 69.2+10.4 kg) and 10 older males and females (72.6+4.7 years, 1.70+.12 m, 74.3+14.6 kg) performed randomized sessions of HL (80% 1-RM for 3 sets of 10 isotonic knee extension repetitions) and low-load, high-velocity BFR (30% 1-RM coupled with a vascular restriction for one set of 30 knee extension repetitions and 3 sets of 15 repetitions completed as quickly as possible). Knee extension isometric torque was assessed before and after each session of exercise and neuromuscular activation of the vastus lateralis (VL) was quantified with surface electromyography (EMG). RESULTS: The young participants had higher isometric torque than the older participants (213.4+54.8 vs 160.1+56.3 Nm; P=.01). There was an average decrement in torque of 31.4+9.2% among all participants from baseline to post exercise (P<.01). The magnitude of this decrement was similar between conditions (P=.19), age (P=.12), and the interaction of time, condition and age (P=.16). EMG amplitude normalized to pre isometric torque in the first 5 knee extension repetitions of the HL condition averaged 106+57% and 90+33% in the BFR high-velocity condition. In the last 5 repetitions, EMG amplitude averaged 117+56% and 113+46 in the HL and BFR conditions respectively. This was a significant increase in EMG amplitude (P<.01) but there were no interactions or main effects of condition or age (P>.05). CONCLUSION: Combing high-velocity contractions with BFR resistance exercise results in decrements in torque and heightened neuromuscular activation similar to HL exercise in both young and older adults. Future studies should evaluate the training adaptations from high-velocity BFR resistance training. Supported by University of New Hampshire Grimes Family Fund.

The Effect Of Blood Flow Restriction Resistance Training On Exercise-induced Hypoalgesia

PURPOSE: Exercise-induced hypoalgesia (EIH) describes a reduction in pain sensitivity following exercise, characterised by an elevation in pain threshold or decrease pain intensity ratings following exercise. Recent research suggests that performing light-load resistance exercise with blood flow restriction (BFR-RE) may have a pain-modulation effect. Therefore, the aim of this study was to compare the magnitude of EIH with BFR-RE to resistance exercise at both low and high intensities. METHODS: Twelve recreationally active individuals were recruited to participate. In a randomised crossover design, participants completed 4 experimental trials of resistance exercise ((1) light load resistance exercise (LLRE); (2) BFR-RE with low pressure (BFR40); (3) BFR-RE with high pressure (BFR80) and (4) heavy load resistance exercise (HLRE)). Pressure pain threshold (PPT) was then assessed at multiple body sites (dominant and non-dominant quadriceps and non-dominant trapezius muscle) pre, 5 min, 10 min and 24 hr post exercise. RESULTS: There was a two-way interaction effect for the dominant quadriceps site. Post-hoc analysis showed that, compared to LLRE, PPT was higher following BFR40, BFR80 and HLRE. PPT was higher following BFR80 compared to BFR40 and HLRE. At 24h post-exercise, PPTs were 14.5 ± 6.7% and 23.9 ± 8.2% higher than pre-exercise values in the BFR40 and BFR80 trials, respectively, whereas PPTs had returned to baseline in the LLRE and HLRE trials. Compared to LLRE, the increase in PPT was greater following BFR40 (0.28 ± 0.13 AU), BFR80 (0.64 ± 0.42 AU) and HLRE (0.34 ± 0.20 AU) in the non-dominant quadriceps. At 24h PPTs had returned to baseline. Compared to LLRE, the increase in PPT was greater following BFR40 (0.31 ± 0.27 AU), BFR80 (0.30 ± 0.17 AU), and HLRE (0.26 ± 0.13 AU) for the trapezius. At 24h PPTs had returned to baseline. CONCLUSIONS: In conclusion BFR with higher pressure leads to EIH in both dominant and non-dominant limbs suggesting both central and peripheral mechanisms of action.

Combining Blood Flow Restriction Training With Heat To Maximize Hypertrophy And Strength In Rugby Players

PURPOSE: We assessed whether blood flow restriction (BFR) training with the addition of heat stress (BFRH) improves hypertrophy, muscle strength and sport-specific physical performance in rugby union players, compared to BFR training alone. METHODS: Nineteen elite U23 rugby union male players were randomly assigned to BFRH (n = 7), BFR (n = 6) or traditional high-load resistance training (CON, n = 6) groups. BFRH and BFR groups trained twice weekly for 3 weeks using BFR exercise (half squat, 4 sets of 30-15-15-15 repetitions at 30% 1 maximum repetition (1RM) with 30 s of passive recovery; 50% of resting arterial occlusion pressure) in hot (37°C) and cool (22°C) conditions, respectively. Before and after the intervention, thigh circumference, half squat 1RM, squat jump force-velocity profile, and performance in vertical jump, sprint and repeated-sprint ability (RSA) tasks were measured. Muscle damage marker (creatine kinase) was measured before and after (0.1-24 h) the first and last training session. RESULTS: Thigh circumference significantly increased (P<0.001) from pre- to post-training in both BFRH (+6%, P<0.001) and BFR (+4%, P<0.05). Significant time × group interaction revealed improvement in half squat 1RM (+12% and +19%, P<0.01) and maximal force component (+102% and +116%, P<0.001) of the force-velocity profile for BFRH and BFR. Vertical jump performance did not change. 10-m sprint (-5% and -3%, P<0.001) and RSA best and total times (both -2%, both P≤0.001) improved similarly in BFRH and BFR. Although not significant, muscle damage was lowered after the last session in BFRH only. No pre- to post-training changes occurred in CON. CONCLUSIONS: Combining BFR training with heat stress can potentially induce hypertrophy and improve rugby union-specific physical performance while also inducing lower muscle damage than BFR training alone. Such gains could be of benefit during competitive period or rehabilitative setting.

Hemodynamic and Hemostatic Response to Blood Flow Restriction Resistance Exercise in Coronary Artery Disease

Blood flow-restricted resistance training (BFR-RT) has been proven to be safe and efficacious in healthy older adults, but not in cardiovascular disease. The aim of this study was to investigate the acute and training induced effects of BFR-RT on hemostatic and hemodynamic responses in patients with coronary artery disease (CAD). Stable patients with CAD were randomized to 8 weeks of BFR-RT (30%-40% 1-repetition maximum unilateral knee extension) combined with aerobic training or aerobic training alone (control group). At baseline and after 4 and 8 weeks, blood samples were taken before and after BFR exercise, whereas hemodynamic parameters were monitored throughout the exercise. Twenty-four patients (12 per group; mean age, 60 ± 2 years; mostly male [75%]) completed the study. The BFR-RT significantly improved systolic blood pressure (-10 mm Hg; P = .020) and tended to lower diastolic blood pressure (-2 mm Hg; P = .066). In contrast, no posttraining alterations were observed in N-terminal prohormone B-type natriuretic hormone, fibrinogen, and D-dimer values. During BFR exercise, all hemodynamic variables significantly increased after the first and second set, whereas blood pressure immediately lowered after the cuff was released in the third set. Last, significant interaction was only observed for repetitions × intensity (P < .001; partial η2 = 0.908) of diastolic blood pressure at higher exercise intensity (40% 1-repetition maximum). The BFR-RT was proven to be safe, with favorable hemodynamic and hemostatic responses in patients with CAD, and can be recommended as an additional exercise modality in cardiac rehabilitation.Trial Registration:ClinicalTrial.gov Identifier: NCT03087292.

Short-Term Blood Flow Restriction Increases Power Output and Bar Velocity During the Bench Press.

Wilk, M, Krzysztofik, M, Filip, A, Zajac, A, Bogdanis, GC, and Lockie, RG. Short-term blood flow restriction increases power output and bar velocity during the bench press. J Strength Cond Res 36(8): 2082-2088, 2022-This study examined the effect of blood flow restriction (BFR) with 2 different types of cuffs on peak power output (PP), mean power output (MP), peak bar velocity (PV), and mean bar velocity (MV) in the bench press exercise (BP). Fourteen healthy strength-trained male athletes (age = 27.6 ± 3.5 years; body mass = 84.1 ± 8.0 kg; height = 175.8 ± 6.7 cm; BP 1 repetition maximum [RM] = 138.6 ± 17.8 kg) performed 3 different testing protocols as follows: without BFR (NO-BFR), BFR with a narrow cuff (BFR NARROW ), and BFR with a wide cuff (BFR WIDE ) in a randomized crossover design. During all sessions, subjects performed one set of 3 repetitions of the BP exercise using 70% 1RM. Cuff pressure was set to approximately 90% full arterial occlusion pressure of the upper limb at rest. Analyses of variance showed an increase in PP (by 21%, p < 0.01; effect size [ES] = 1.67), MP (by 16%, p < 0.01; ES = 0.93), PV (by 22%, p < 0.01; ES = 1.79), and MV (by 21%, p < 0.01; ES = 1.36) during BFR WIDE compared with NO-BFR and a significant increase in PP (by 15%, p < 0.01; ES = 1.07), MP (by 17%, p < 0.01; ES = 0.78), PV (by 18%, p < 0.01; ES = 1.65), and MV (by 13% p < 0.01; ES = 1.00) during BFR WIDE compared with BFR NARROW . There were no significant differences in any of the variable between NO-BFR and BFR NARROW . The results of the study indicate that short-term BFR training increases power output and bar velocity during the BP exercise. However, only BFR WIDE significantly influenced bar velocity and power output, which indicates that the width of the cuff is a critical factor determining acute exercise adaptation during BFR resistance training.

Effects of alternating blood flow restricted training and heavy-load resistance training on myofiber morphology and mechanical muscle function.

To investigate if short-term block-structured training consisting of alternating weeks of blood flow restricted low-load resistance training (BFR-RT) and conventional free-flow heavy-load resistance training (HL-RT) leads to superior gains in mechanical muscle function, myofiber size, and satellite cell (SC) content and myonuclear number compared with HL-RT alone. Eighteen active young participants (women/men: 5/13, 23 ± 1.2 yr) were randomized to 6 wk (22 sessions) of lower limb HL-RT [70-90% one repetition maximum (1-RM)] (HRT, n = 9) or block-structured training alternating weekly between BFR-RT (20% 1-RM) and HL-RT (BFR-HRT, n = 9). Maximal isometric knee extensor strength (MVC) and muscle biopsies (VL) were obtained pre- and posttraining to examine changes in muscle strength, myofiber cross-sectional area (CSA), myonuclear (MN) number, and SC content. MVC increased in both training groups (BFR-HRT: +12%, HRT: +7%; P < 0.05). Type II myofiber CSA increased similarly (+16%) in BFR-HRT and HRT (P < 0.05), while gains in type I CSA were observed following HRT only (+12%, P < 0.05). In addition, myonuclear number remained unchanged, whereas SC content increased in type II myofibers following HRT (+59%, P < 0.05). Short-term alternating BFR-RT and HL-RT did not produce superior gains in muscle strength or myofiber size compared with HL-RT alone. Noticeably, however, conventional HL-RT could be periodically replaced by low-load BFR-RT without compromising training-induced gains in maximal muscle strength and type II myofiber size, respectively.NEW & NOTEWORTHY The present data demonstrate that periodically substituting heavy-load resistance training (HL-RT) with low-load blood flow restricted resistance training (BFR-RT) leads to similar gains in type II myofiber CSA and muscle strength as achieved by HL-RT alone. Furthermore, we have for the first time evaluated myonuclear content and myonuclear domain size before and after training intervention across separate fiber size clusters and found no within-cluster changes for these parameters with training.

Eccentric, but not concentric blood flow restriction resistance training increases muscle strength in the untrained limb

ObjectivesLittle is known regarding the variables or mechanisms mediating cross-education as a result of resistance training. Therefore, the purpose of the present study was to examine the effects of low-load eccentric-only blood flow restriction (Ecc-BFR) and low-load concentric-only BFR (Con-BFR) on indices of cross-education. DesignThirty-six women were randomly assigned to 4-wks of unilateral resistance training with Ecc-BFR (n = 12), Con-BFR (n = 12) or control (no intervention, n = 12) group. Eccentric peak torque, concentric peak torque, maximal voluntary isometric contraction torque, muscle thickness, and muscle activation were assessed from the contralateral, untrained arm. ResultsMuscle strength (collapsed across mode) increased from 0-wk to 2-wks (4.9%) and 4-wks (13.0%) for Ecc-BFR only. There were increases in muscle activation (collapsed across mode and group) regardless of training modality, but there were no changes in muscle size for any of the conditions. ConclusionsThe findings of the present study indicated that low-load Ecc-BFR increased muscle strength. The increases in muscle strength as a result of Ecc-BFR were not mode-specific. Thus, low-load Ecc-BFR provides a unique alternative to maintain muscle function in an untrained limb that may have application during limb immobilization and rehabilitation practices.

RESIST! Blood-flow Restriction Resistance Training for Improving Insulin Sensitivity in Type 2 Diabetes

RESIST! Blood-flow Restriction Resistance Training for Improving Insulin Sensitivity in Type 2 Diabetes

Determining the optimal blood flow restriction protocol for maximising muscle hypertrophy and strength, pressure and cuff width: A mini-review

Low load resistance training accompanied by blood flow restriction (BFR) has been established as a training modality to induce hypertrophy and strength adaptations. Throughout the BFR-literature, several protocols have emerged with a vast difference among manipulations regarding limb occlusion pressure and the use of different cuff sizes. The aim of this review is to summarise the research underpinning the stimulus regarding alterations in occlusion pressure and the use of different cuff widths, thus investigate whether an optimal protocol is evident. While the focal point of BFR-literature supports the efficiency of several BFR-protocols, no uniform BFR-protocol are located in the literature to maximise muscle hypertrophy and strength. However, an optimal limb occlusion pressure is crucial to achieve venous blood pooling, thus induce a significant stimulus to the muscle, and should be individualised and likely applied relative to the maximum arterial occlusion pressure. Quantification of the optimal pressure range is currently a disputed topic, with no conclusive evidence leading to the most efficient range of applied pressure. Regarding cuff widths, applying an absolute or relative pressure, and their implications regarding the hemodynamics of blood flow should be considered by the researchers. The author would highlight that future BFR studies should be conducted to shed light on the determinants underpinning the protocol to optimise muscle hypertrophy and strength through BFR resistance training, which could have an important ramification through its increasing use in clinical settings and athletic development.

Low-load blood flow restriction elicits greater concentric strength than non-blood flow restriction resistance training but similar isometric strength and muscle size.

Low-load venous blood flow restriction resistance training (RT + BFR) has been demonstrated to increase muscle strength to a greater degree than low-load non-BFR resistance training (RT) during isotonic training, but no previous investigations have examined RT + BFR versus RT during isokinetic training. The purpose of the present study was to examine the effects of 4 weeks of isokinetic low-load RT + BFR versus low-load RT on indices of muscle strength, muscle size, and neural adaptations. Thirty women (mean ± SD; 22 ± 2years) participated in this investigation and were randomly assigned to 4 weeks of either RT + BFR (n = 10), RT (n = 10), or control (n = 10) group. Resistance training consisted of 75 reciprocal forearm flexion-extension isokinetic muscle actions of the forearm flexors performed at a velocity of 120°s-1. Concentric peak torque increased to a greater extent for RT + BFR after 4 weeks (36.9%) compared to RT (25.8%), but there were similar increases in isometric torque (23.3-42.1%). For both RT + BFR and RT, there were similar increases in muscle cross-sectional area and muscle thickness of the biceps brachii after 2 weeks (11.3-14.3% and 12.4-12.9%, respectively) and 4 weeks (18.7-21.9% and 19.0-20.0%, respectively). There were similar increases in mechanomyographic amplitude, mechanomyographic mean power frequency, and electromyographic mean power frequency, but no changes in electromyographic amplitude for all conditions (including control). These findings indicated that low-load RT + BFR elicited greater increases in concentric strength than low-load RT, but elicited comparable increases in isometric strength and muscle size. There were also no differences in any of the EMG and MMG responses among conditions.