Addition Of Blood Flow Restriction Research Articles

Affective, perceptual and physiologic responses to isokinetic contractions under blood flow restriction.

Blood flow restriction (BFR) has been shown to enhance the effectiveness of low load resistance exercise, but less research has examined its utility in conjunction with maximal isokinetic contractions, which may depend on the restrictive pressure and speed of contraction. Individuals reported to the laboratory for three visits to complete three sets of 20 maximal elbow flexion exercises at 60°/s and 300°/s under 0%, 40% and 80% of their arterial occlusion pressure. Muscle thickness was measured before and after exercise, and ratings of discomfort, perceived activation, and exercise-induced feelings were obtained at the completion of each exercise. Fatigue was assessed as the decline in average peak torque across the three sets. A total of 27 individuals (11 females, 16 males) completed the study. There was a significant interaction for torque at both 60°/s and 300°/s (P<0.001), with each increasing pressure resulting in greater fatigue. Muscle swelling was present across all conditions but was lowest in the 40% BFR condition applied during the 300°/s speed. At both 60°/s and 300°/s speeds, the 80% BFR pressure was associated with lower enjoyment, greater discomfort, and greater perceived activation (all P<0.05). The combined effects of BFR to maximal isokinetic contractions increased fatigue with less of an impact on muscle swelling. These results indicate that BFR may enhance the effectiveness of long-term isokinetic training, but it is also important to consider the addition of BFR was associated with lower levels of enjoyment and greater discomfort which may decrease adherence.

Addition of Blood Flow Restriction in Squat Exercises to Increase the Strength of Quadriceps Muscle Groups

Addition of Blood Flow Restriction in Squat Exercises to Increase the Strength of Quadriceps Muscle Groups

Repeated-Sprint Training With Blood-Flow Restriction Improves Repeated-Sprint Ability Similarly to Unrestricted Training at Reduced External Loads.

This study examined performance and physiological adaptations following 3 weeks of repeated-sprint training (RST) with blood-flow restriction (BFR) or without (non-BFR). Twenty-six semiprofessional and amateur adult male team-sport players were assessed for repeated-sprint ability, anaerobic capacity, leg lean mass, neuromuscular function, and maximal aerobic capacity before and after RST. Participants completed 9 cycling RST sessions (3 sets of 5-7 × 5-s sprints, 25-s passive recovery, 3-min rest) over a 3-week period with BFR or non-BFR. During RST sessions, the BFR group demonstrated lower mean power output compared with non-BFR (-14.5%; g = 1.48; P = .001). Significant improvements (P < .05) in mean and peak power output during repeated-sprint ability (+4.1%; g = 0.42, and + 2.2%; g = 0.25, respectively) and anaerobic capacity (+4.8%; g = 0.47, and + 4.7%; g = 0.32, respectively) tests, leg lean mass (+2.0%; g = 0.16), and peak aerobic power (+3.3%; g = 0.25) were observed from pretesting to posttesting without any between-groups differences. No significant changes (P > .05) were observed for maximal isometric voluntary contraction and maximal aerobic capacity. Peak rate of force development decreased (P = .003) in both groups following RST (-14.6%; g = 0.65), without any between-groups differences. Repeated-sprint ability, anaerobic capacity, leg lean mass, and peak aerobic power improved following 3 weeks of RST; however, the addition of BFR did not further enhance adaptations. Interestingly, comparable improvements were achieved between groups despite lower external loads experienced during RST sessions with BFR.

The effect of blood flow restriction in low-intensity load exercise on isokinetic strength of the quadriceps muscles in knee osteoarthritis

Link of Video Abstract: https://youtu.be/tduoO-xy3ZE Introduction: Cartilage destruction in knee osteoarthritis (KOA) caused the inflammation process. It makes the patient complain of knee pain, tends to immobilize, and induced neural inhibition (Arthrogenic muscle inhibition) on the quadriceps muscle as a knee stabilator and shock absorbent. These caused quadriceps weakness. The combination of blood flow restriction (BFR) and low-intensity resistance training (LIRT) showed an improvement in isotonic peak torque significantly, but the prescription is varied and limited in Indonesia. Patient and Methods: This was a clinical experimental study with randomized control trial with pre and post-test design. The subjects were 28 KOA patients (50-70 years old). The intervention group (n=14) received a combination of low-load resistance training (30% 1-RM; 75 repetitions) and BFR (50 mmHg). The control group (n=14) received low load resistance training only (30% 1-RM; 75 repetitions). Both groups received training 2 times per week with a Q-bench machine for 6 weeks. Isokinetic peak torque was assessed before and after the training program. Results: There was a significant improvement in isokinetic peak torque before and after the training program in both groups (intervention group p=0.001; control group p=0.000). There was a significant improvement of delta isokinetic peak torque between both groups (p=0.018) and post-test between both groups (p=0.044). The effect size value of the intervention group was 1.22 (very large) and the control group was 0.89 (large). Conclusions: The addition of BFR on LIRT for 6 weeks can improve isokinetic quadriceps strength in patients with knee osteoarthritis

Blood flow restriction does not alter the early hypertrophic signaling and short-term adaptive response to resistance exercise when performed to task failure.

Previous research supports that low-load resistance exercise with blood flow restriction (LL-BFR) acutely increases physiological responses and muscle mass accrual compared with low-load resistance exercise (LL-RE) alone. However, most studies have work-matched LL-BFR and LL-RE. Completing sets to similar perceived efforts, thereby allowing for a variable amount of work, may provide a more ecologically valid approach to compare LL-BFR and LL-RE. This study aimed to examine acute signaling and training responses following LL-RE or LL-BFR performed to task failure. Ten participants had each leg randomly assigned to perform LL-RE or LL-BFR. Muscle biopsies were obtained before and 2-h after the first exercise bout and after 6-wk of training for Western blot and immunohistochemistry analyses. Repeated measure ANOVA and intraclass coefficients (ICCs) were used to compare responses of each condition. After exercise, AKT(T308) phosphorylation increased after LL-RE and LL-BFR (both ∼145% of baseline, P < 0.05) and trended for p70 S6K(T389) (LL-RE: ∼158% and LL-BFR: ∼137%, P = 0.06). BFR did not alter these responses, resulting in fair-excellent ICCs for signaling proteins involved in anabolism (ICCAKT(T308) = 0.889, P = 0.001; ICCAKT(S473) = 0.519, P = 0.074; ICCp70 S6K(T389) = 0.514, P = 0.105). After training, muscle fiber cross-sectional area and vastus lateralis whole muscle thickness were similar between conditions (ICC ≥ 0.637, P ≤ 0.031). Similar acute and chronic responses between conditions and high ICC values between legs suggest that both LL-BFR and LL-RE performed by the same person result in similar adaptations. These data support the concept that sufficient muscular exertion is a key factor for training-induced muscle hypertrophy with low-load resistance exercise independent of total work and blood flow.NEW & NOTEWORTHY The addition of blood flow restriction during low-load resistance exercise is considered to increase the signaling events and muscle growth responses to a greater extent than low-load resistance exercise alone. It remains unclear whether blood flow restriction accelerates or increases these adaptive responses, as most studies have each condition perform the same amount of work. Despite different amounts of work performed, we show similar signaling and muscle growth responses occur after low-load resistance exercise with and without blood flow restriction. Our work supports that blood flow restriction accelerates fatigue but does not increase the signaling events and muscle growth responses during low-load resistance exercise.

The impact of blood flow restricted electrical stimulations on recovery from muscle damage.

Both electrical stimulations (E-STIM) and blood flow restriction (BFR) have been shown to treat symptoms of exercise-induced muscle damage, but little is known about their combined effects which was the purpose of this study. Individuals completed one set of eccentric elbow flexion exercises to induce muscle damage. Forty-eight hours later, E-STIM was applied using an interferential current administered to both arms for 20 min; however, only one arm completed the E-STIM protocol while also undergoing repeated bouts of BFR (full occlusion for 2 min separated by a 1-min rest intervals). Discomfort and isometric strength were assessed immediately before the damaging exercise, immediately before the treatments, and 0, 10, and 30 min posttreatment. A total of 22 individuals (11 females) completed the study. There were no interactions with respect to discomfort (BF10 = 0.008) or isometric strength (BF10 = 0.009) indicating that the addition of BFR did not alter the effectiveness of E-STIM. There was a main effect of time indicating that the damaging exercise was successful at depressing torque (pre: 284 N, post: 199 N; BF10 = 2.70e9) and inducing discomfort (pre: 0 au, post: 6.4 au; BF10 = 3.21e17). While isometric strength did not recover with the E-STIM treatments, discomfort was reduced at each the immediate post (5.3 au; BF10 = 56 294) 10-min post (5.0 au; BF10 = 46 163), and 30-min post (4.9 au; BF10 = 707 600) time points. E-STIM may be useful for treating discomfort, but does not appear capable of recovering strength associated with muscle damage. The efficacy of E-STIM would not appear to be enhanced if performed under BFR.

The Hypoalgesic Effect of Low-Load Exercise to Failure Is Not Augmented by Blood Flow Restriction

ABSTRACTPurpose: To 1) examine whether blood flow restriction would provide an additional exercise-induced hypoalgesic response at an upper and lower limb when it is incorporated with low-load resistance exercise until failure, and 2) examine if increases in blood pressure and discomfort, with blood flow restricted exercise, would mediate the exercise-induced hypoalgesia over exercise without blood flow restriction. Methods: Forty healthy young participants completed two trials: four sets of unilateral knee extension exercise to failure at 30% of one-repetition maximum, with and without blood flow restriction. Pressure pain thresholds were assessed before (twice) and 5-min post exercise at an upper and lower limb. Blood pressure and discomfort ratings were recorded to examine mediating effects on exercise-induced hypoalgesia with blood flow restricted exercise. Results: Pressure pain threshold increased following both exercise conditions compared to a control, without any differences between exercise conditions at the upper (exercise conditions vs. control: ~0.37 kg/cm2) and lower (exercise conditions vs. control: ~0.60 kg/cm2) limb. The total number of repetitions was lower for exercise with blood flow restriction compared to exercise alone [median difference (95% credible interval) of −27.0 (−29.8, −24.4) repetitions]. There were no mediating effects of changes in blood pressure, nor changes in discomfort, for the changes in pressure pain threshold at either the upper or lower limb. Conclusion: The addition of blood flow restriction to low-load exercise induces a similar hypoalgesic response to that of non-blood flow restricted exercise, with a fewer number of repetitions.

Effect Of Blood Flow Restricted Knee Extension On Exercise-induced Hypoalgesia At Upper And Lower Limb

Previous research using repetition matched conditions found greater hypoalgesic responses to low load blood flow restricted exercise compared to non-blood flow restricted exercise. However, it is unknown if the addition of blood flow restriction to low load exercise can elicit any additional exercise-induced hypoalgesic effects when the exercise is taken to failure. PURPOSE: To examine the effect of knee extension exercise with blood flow restriction on exercise-induced hypoalgesia at an upper and lower limb. METHODS: 20 participants performed 2 trials in a random order: knee extension exercise at 30% of one-repetition maximum (KE); and KE with blood flow restriction at 80% of resting arterial occlusion pressure (KE + BFR). The KE exercise involved 4 sets of unilateral knee extension until failure with 30-sec rest intervals between sets. The total number of repetitions for each condition was recorded. Pressure pain thresholds (PPT) were assessed before (twice) and 5-min post exercise at an upper (forearm) and lower (tibialis anterior) limb. The change scores between two pre-exercise measurements (11 minutes apart) from both conditions were averaged and used as a control (CON). A Bayesian paired-samples t-test was performed to assess differences in the total number of repetitions, and a Bayesian one-way ANOVA of change scores was used to examine if the exercise-induced hypoalgesia changed differently between conditions. RESULTS: At the upper limb, PPT increased following both exercise conditions compared to CON (KE: 0.36 kg/cm2, KE + BFR: 0.35 kg/cm2, CON: -0.01 kg/cm2, BF10 = 3167.8) without any differences between exercise conditions. At the lower limb, PPT increased following both exercise conditions compared to CON (KE: 0.56 kg/cm2, KE + BFR: 0.64 kg/cm2, CON: -0.01 kg/cm2, BF10 = 4.260e+6) without any differences between exercise conditions. The total number of repetitions was lower in KE + BFR (39.6 repetitions) compared to KE (68.4 repetitions) (BF10 = 3.260e+8). CONCLUSIONS: Performing an acute bout of low load knee extension exercise until failure with blood flow restriction did not provide additional exercise-induced hypoalgesia. However, the addition of blood flow restriction can induce similar hypoalgesic response to that of non-blood flow restricted exercise with a fewer number of repetitions.

Acute effects of resistance exercise with blood flow restriction on cardiovascular response: a meta-analysis.

Aim: To compare the acute effects of low-load resistance training associated with blood flow restriction (LLRT-BFR) with low-load resistance training (LLRT) and high-load resistance training (HLRT) on cardiovascular outcomes in healthy individuals. Methods: This review was registered and the studies were selected using seven databases. Randomized controlled clinical trials were includedthat evaluated LLRT-BFR compared with LLRT and HLRT in young individuals for the cardiovascular outcomes. Results: 19studies were included. In the comparison of LLRT-BFR with HLRT, there were significant differences for cardiac output and heart rate - with reduced values and in favor of LLRT-BFR. Conclusion: There are no greater acute effects of the addition of blood flow restriction, with the exception of the reduction in cardiac output and heart rate for LLRT-BFR compared with HLRT.

The Effect of Blood Flow Restriction Training on Muscle Atrophy Following Meniscal Repair or Chondral Restoration Surgery in Active Duty Military: A Randomized Controlled Trial.

Recently, blood flow restriction (BFR) training has gained popularity as an alternative to high-load resistance training for improving muscle strength and hypertrophy. Previous BFR studies have reported positive treatment effects; however, clinical benefits to using BFR following meniscal repair or chondral surgery are unknown. The purpose of this study was to determine the effect of resistance exercises with BFR training versus exercises alone on self-reported knee function, thigh circumference, and knee flexor/extensor strength postmeniscal or cartilage surgery. Single-blinded randomized controlled trial in an outpatient military hospital setting. Twenty participants were randomized into 2 groups: BFR group (n = 11) and control group (n = 9). Participants completed 12weeks of postoperative thigh strengthening. The BFR group performed each exercise with the addition of BFR. Both groups continued with the prescribed exercises without BFR from 12weeks until discharged from therapy. Thigh circumference and self-reported knee function were measured at 1, 6, 12, and 24weeks postoperatively along with knee extensor and flexor strength at 12 and 24weeks. Change scores between time points were calculated for knee function. Limb symmetry indices (LSI) were computed for thigh circumference and knee strength variables. Seventeen participants were included in the final analyses (BFR = 8 and control = 9) due to COVID-19 restrictions. There were no interactions or main effects for group. Time main effects were established for change in knee function scores, thigh circumference LSI, and knee extensor strength LSI. However, knee flexor strength LSI had no main effect for time. The outcomes of this trial suggest that resistance exercises with and without BFR training may result in similar changes to function, thigh atrophy, and knee extensor strength postmeniscus repair/chondral restoration, though further study with larger sample sizes is needed.

Impact of strengthening exercises with and without blood flow restriction on quadriceps of knee osteoarthritis patients.

To determine the effect of blood flow restriction with strengthening exercises on knee osteoarthritis patients. The case-control study was conducted at the Department of Physical Medicine and Rehabilitation, Combined Military Hospital, Okara, Pakistan, from June to December 2018, and comprised knee osteoarthritis patients who were assigned to two equal groups. The cases in Group A received strengthening exercises with blood flow restriction, while the controls in Group B received strengthening exercises without blood flow restriction. Both groups were given 4 sessions of treatment per week with 5-minute warm-up on a stationary bike for 4 weeks. Outcome was measured using visual analogue scale, Kujala scoring questionnaire and muscle girth measurement. Data was analysed using SPSS 20. Of the 30 patients, 15(50%) were in each of the two groups. There were 20(66.7%) females and 10(33.3%) men with an overall mean age of 66.5}6.5 years. Also, 18(60%) subjects were overweight on the basis of body mass index. There were significant improvement in terms of pain and disability in both the groups (p<0.05)), but only Group A showed significant improvement in muscle girth (p<0.05). Overall there was no significant difference between the groups (p>0.05). Strengthening exercises reduced pain and disability, but the addition of blood flow restriction had no significant impact except in terms of muscle size.

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.

Isometric blood flow restriction exercise: acute physiological and neuromuscular responses

BackgroundNumerous studies have demonstrated that the addition of blood flow restriction (BFR) to low-load (LL) resistance exercise leads to elevated levels of muscle hypertrophy and strength gains. In terms of main underlying mechanisms, metabolic accumulation and increased neuromuscular adaptations seem to play a primary role. However, this evidence is largely based on dynamic exercise conditions. Therefore, the main objective was to investigate the acute physiological adaptations following isometric LL-BFR exercise.MethodsFifteen males participated in this cross-over trial and completed the following sessions in a random and counterbalanced order: isometric LL-BFR exercise (20% maximum voluntary contraction, MVC) and load matched LL exercise without BFR. Lactate levels, muscle activation as well as muscle swelling were recorded during the whole exercise and until 15 min post completion. Additionally, changes in maximal voluntary torque and ratings of perceived exertion (RPE) were monitored.ResultsDuring exercise, EMG amplitudes (72.5 ± 12.7% vs. 46.3 ± 6.7% of maximal EMG activity), muscle swelling and RPE were significantly higher during LL-BFR compared to LL (p < 0.05). Lactate levels did not show significant group differences during exercise but revealed higher increases 15 min after completion in the LL-BFR condition (LL-BFR: + 69%, LL: + 22%) (p < 0.05). Additionally, MVC torque significantly decreased immediately post exercise only in LL-BFR (~ − 11%) (p < 0.05) but recovered after 15 min.ConclusionsThe present results demonstrate that isometric LL-BFR causes increased metabolic, neuromuscular as well as perceptual responses compared to LL alone. These adaptations are similar to dynamic exercise and therefore LL-BFR represents a valuable type of exercise where large joint movements are contraindicated (e.g. rehabilitation after orthopedic injuries).

Acute Neuromuscular and Microvascular Responses to Concentric and Eccentric Exercises With Blood Flow Restriction.

Lauver, JD, Cayot, TE, Rotarius, TR, and Scheuermann, BW. Acute neuromuscular and microvascular responses to concentric and eccentric exercises with blood flow restriction. J Strength Cond Res 34(10): 2725-2733, 2020-The purpose of this study was to investigate the effects of the addition of blood flow restriction (BFR) during concentric and eccentric exercises on muscle excitation and microvascular oxygenation status. Subjects (N = 17) were randomly assigned to either a concentric (CON, CON + BFR) or eccentric (ECC, ECC + BFR) group, with one leg assigned to BFR and the other to non-BFR. Surface electromyography and near-infrared spectroscopy were used to measure muscle excitation and microvascular deoxygenation (deoxy-[Hb + Mb]) and [total hemoglobin concentration] during each condition, respectively. On separate days, subjects completed 4 sets (30, 15, 15, 15) of knee extension exercise at 30% maximal torque, and 1 minute of rest was provided between the sets. Greater excitation of the vastus medialis was observed during CON + BFR (54.4 ± 13.3% maximal voluntary isometric contraction [MVIC]) and ECC + BFR (53.0 ± 18.0% MVIC) compared with CON (42.0 ± 10.8% MVIC) and ECC (46.8 ± 9.6% MVIC). Change in deoxy-[Hb + Mb] was greater during CON + BFR (10.0 ± 10.4 μM) than during CON (4.1 ± 4.0 μM; p < 0.001). ECC + BFR (7.8 ± 6.7 μM) was significantly greater than ECC (3.5 ± 4.7 μM; p = 0.001). Total hemoglobin concentration was greater for ECC + BFR (7.9 ± 4.4 μM) compared with ECC (5.5 ± 3.5 μM). The addition of BFR to eccentric and concentric exercises resulted in a significant increase in metabolic stress and muscle excitation compared with non-BFR exercise. These findings suggest that although BFR may increase the hypertrophic stimulus during both modes of contraction, BFR during concentric contractions may result in a greater stimulus.

Physiological Responses To Intermittent Blood Flow Restriction During Cycling Exercise

Aerobic exercise with the addition of blood flow restriction (BFR) has the potential to elicit physiological adaptations. However, the acute physiological and perceptual responses during aerobic exercise with intermittent BFR remains unclear. PURPOSE: The purpose of this investigation was to examine the physiological and perceptual responses to intermittent BFR compared to low- (LIIE) and high-intensity interval exercise (HIIE). METHODS: Participants randomly performed 3 interval (INT) exercise protocols: BFR, LIIE and HIIE. BFR and LIIE consisted of 10 INTs of 2-min of work at 70% of ventilatory threshold (VT) and 1-min of recovery (20 W). During BFR, the cuffs were inflated to 80% of limb occlusion pressure (154 ± 17 mmHg) during each work INT and deflated during recovery INTs. HIIE consisted of 5 INTs at 140% of VT and 1-min of recovery (20 W). Pulmonary VO2 and respiratory exchange ratio (RER) were recorded and tissue oxygen saturation (StO2) was assessed by near-infrared spectroscopy. The level of perceived exertion (RPE) was assessed at the end of each INT. INTs 2, 4, 6, 8, and 10 during BFR and LIIE were used for comparison with INTs 1-5 during HIIE. The last 30 seconds of each INT were used for analysis. StO2 during each condition is expressed as change from baseline cycling (20W) (arbitrary units; AU). Two-way (INT x trial) ANOVAs analyzed differences. Significance was established if p<0.05. RESULTS: There was a main effect of trial for VO2 and RER. VO2 was greater in HIIE (INT 5 = 2.12 ± 0.56 L*min-1) than BFR (INT 10 = 1.41 ± 0.21 L*min-1) and LIIE (INT 10 = 1.28 ± 0.27 L*min-1). RER was lower in LIIE (INT 10 = 0.93 ± 0.01) compared to BFR (INT 10 = 0.94 ± 0.06) and HIIE (INT 5 = 0.99 ± 0.03). At all points, HR was lower in LIIE (INT 10 = 110 ± 10 bpm) than BFR (INT 10 = 155 ± 24 bpm) and HIIE (INT 5 = 154 ± 14 bpm). There were no differences in HR between BFR and HIIE. Delta StO2 was greater during BFR (INT 10 = -37.5 ± 15.6 AU) and HIIE (INT 5 = -34.2 ± 6.5 AU) compared to LIIE (INT 10 = -14.6 ± 8.67 AU). During all points, RPE was greater in BFR (INT 10 = 15.0 ± 2.4) and HIIE (INT 5 = 14.3 ± 1.3) compared to LIIE (INT 10 = 9.3 ± 0.4). CONCLUSIONS: This study suggests that cycling with the addition of intermittent BFR at an intensity equivalent to 70% of VT may provide similar cardiovascular and local physiological stress to traditional HIIE, albeit at a lower work rate.

Concomitant aerobic- and hypertrophy-related skeletal muscle cell signaling following blood flow-restricted walking

This study is aimed to examine the acute responses to a blood flow restriction (BFR) low-intensity aerobic exercise, compared with a similar exercise without BFR, on several aerobic- and hypertrophy-related proteins expression and hormonal responses. On two different occasions, five healthy untrained male subjects were required to perform (i) a BFR low-intensity aerobic exercise consisting of 5 sets of 2-min bouts of walking at an exercise intensity of 63–65% HRmax (equivalent to 40% of VO2max), interspersed by 1-min rest; and (ii) similar exercise bouts without BFR (Ctrl). For each condition, venous blood samples were collected at pre- (baseline), immediately and 2-h post-exercise. Baseline and 3-h post-exercise muscle biopsy samples (vastus lateralis) were also performed for protein expression analysis. HIF-1α, PGC-1α, and VEGF proteins content were significantly higher (P < 0.05) at 3-h post-exercise in BFR compared with baseline values. In reference to baseline, phosphorylation of Akt also increased significantly (P < 0.05) following BFR, and in a greater extent (P < 0.05) than following Ctrl. IGF-1 concentration significantly increased (P = 0.001) immediately following BFR exercise than baseline values and serum GH showed a significant increase (P = 0.046) compared with Ctrl. The addition of blood flow restriction during walking exercise initiate a concomitant cell signaling pathways regulating mitochondrial biogenesis, angiogenesis, and skeletal muscle protein expression. Le but de cette étude est d’examiner les réponses aiguës à un exercice aérobie de faible intensité réalisé avec ou sans occlusion vasculaire (blood flow restriction, [BFR]) sur l’expression de protéines impliquées dans le développement de l’hypertrophie et de l’endurance. Selon un plan croisé, 5 sujets sains non entraînés ont réalisé à deux occasions différentes: (i) 5 séries de 2 min de marche à 63–65 % de la fréquence cardiaque maximale (équivalent à 40 % de la consommation maximale d’oxygène) entrecoupées de 1 min de repos, le tout sous occlusion vasculaire des membres inférieurs (BFR); et (ii) le même exercice sans occlusion (Ctrl). Pour chaque condition, des échantillons sanguins ont été prélevés avant, immédiatement après et 2 h après chaque condition. Des biopsies musculaires (vastus lateralis) ont également été pratiquée au repos (avant exercice) et 3 h après. Le contenu protéique du facteur induit par l’hypoxie 1 alpha (Hypoxic Inducible Factor 1α, HIF-1α), de peroxisome proliferator-activated receptor gamma-coactivator-1alpha (PGC-1α), et du facteur de croissance de l’endothélium vasculaire (Vascular Endothelial Growth Factor, VEGF) ont significativement augmenté (p < 0,05) après l’exercice aérobie BFR. La phosphorylation de la protéine kinase B (Akt) a également augmenté de manière significative (p < 0,05) après l’exercice aérobie BFR et dans une plus grande proportion (p < 0,05) que suite à l’exercice Ctrl. La concentration du facteur de croissance Insulin-like Growth Factor-1 (IGF-1) augmente (p < 0,001) immédiatement après l’exercice aérobie BFR et l’hormone de croissance (sérum GH) augmente significativement (p < 0,05) en comparaison avec Ctrl. L’ajout d’une restriction de la circulation sanguine au cours d’un exercice de marche stimule des voies de signalisation musculaire concomitantes régulant la biogenèse mitochondriale, l’angiogenèse et l’expression des protéines du muscle squelettique.

Occlusion Training During Specific Futsal Training Improves Aspects of Physiological and Physical Performance.

This study aimed to examine the effects of lower limb blood flow restriction (BFR) performed during 3-a-side futsal game training on aerobic and anaerobic performance of futsal players. Twelve male futsal players were randomized into two groups (n = 6); both groups performed ten sessions of the 3-a-side game every other day in half of a futsal court; but one group trained under BFR conditions. Pneumatic cuffs used for the BFR group were inflated to 110% leg systolic blood pressure and increased by 10% after each two completed sessions. Before and after the training sessions subjects completed a series of tests to assess aerobic and anaerobic performances along with changes in blood lactate and anabolic and catabolic hormones. All aerobic and anaerobic performance variables improved in both group after training, however improvements in mean power (12.2%, p = 0.03), run time to fatigue (TTF), (7.1%, p = 0.02) and running economy (RE), (-22.7%, p = 0.01) were significantly greater in the BFR group. There were also significant increases in growth hormone (p = 0.01), testosterone to cortisol ratio at first session (p = 0.01) and rate of lactate removal (p = 0.01) at last session in the BFR group compared to the non-BFR group. Small-sided game (SSG) training with the addition of BFR because of accumulated metabolites and hormonal changed leads to substantially greater increases in performance than SSGs training alone.

Blood flow restriction does not augment low force contractions taken to or near task failure

Low-load exercise performed to or near task failure appears to result in similar skeletal muscle adaptations as low-load exercise with the addition of blood flow restriction (BFR). However, there may be a point where the training load becomes too low to stimulate an anabolic response without BFR. This study examined skeletal muscle adaptions to very low-load resistance exercise with and without BFR. Changes in muscle thickness (MTH), strength, and endurance were examined following 8-weeks of training with a traditional high-load [70% 1RM,(7000)], low-load [15% 1RM,(1500)], low-load with moderate BFR [15%1RM + 40%BFR(1540)], or low-load with greater BFR [15% 1RM + 80%BFR(1580)]. 1RM strength changes were greater in the 7000 condition [2.09 (95% CI = 1.35–2.83) kg] compared to all low-load conditions. For isometric and isokinetic strength, there were no changes. For endurance, there was a main effect for time [mean pre to post change = 7.9 (4.3–11.6) repetitions]. At the 50% site, the mean change in MTH in the 7000 condition [0.16 (0.10–0.22) cm] was greater than all low-load conditions. For the 60% site, the mean change in MTH [0.15 (0.08–0.22)] was greater than all low-load conditions. For the 70% site there was a main effect for time [mean pre to post change = 0.09 (0.05–0.14 cm]. All groups increased muscle size; however, this response was less in all very low training conditions compared to high-load training. 1RM strength increased in the 7000 condition only, with no other changes in strength observed.

Physiological Responses to Intermittent Endurance Exercise with Blood Flow Restriction in the Moderate Intensity Domain

Blood flow restriction (BFR) endurance training may induce both endurance and strength improvements. However, there is no consensus on the ideal BFR endurance exercise prescription in order to balance the physiological and perceptual responses. PURPOSE: The purpose of this investigation was to examine the physiological responses, as well as the perceived exertion in responses to a range of BFR endurance protocols. METHODS: Participants randomly performed 7 exercise protocols: 50% of the difference between peak oxygen uptake (VO2) and ventilatory threshold (VT) (∆50%), 90%, 80%, and 70% of VT with and without BFR. Each protocol consisted of two sets of five work intervals (2 minutes work, 1 minute rest) separated by 5 minutes of recovery. Pulmonary VO2 was recorded breath-by-breath, muscle activation (vastus medialis (VM), vastus lateralis (VL)) was assessed by surface electromyography (sEMG), microvascular oxygenation (tissue oxygenation index (TOI)) was assessed by near-infrared spectroscopy (NIRS), and level of perceived exertion (RPE) was assessed using the Borg scale. The last 30 seconds of intervals 5 and 10 were used for analysis. sEMG data were normalized to baseline cycling (20 watts). TOI during each condition was analyzed compared to baseline cycling and then expressed as change from baseline (arbitrary units) to compare between conditions. RESULTS: The ∆50% protocol resulted in a higher end exercise (interval 10) VO2 compared to all other conditions, no other differences in VO2 were observed. No sEMG differences were observed between conditions (VL- p = 0.24, VM- p = 0.33) or between interval 5 and 10. All BFR conditions resulted in a decrease in TOI from baseline. TOI was greater for all BFR conditions (70%BFR = -36.4 ± 21.9, 80%BFR = -40.4 ± 6.5, 90%BFR = -44.7±7.25) compared to the non-BFR conditions (70% = +4.3 ± 20.2, 80% = +11.8 ± 5.5, 90% = +7.25). No differences in TOI between ∆50 (-36.93 ± 10.8) and any BFR conditions were observed. RPE was greater during 90%BFR (18.0 ± 0) and 80%BFR (17.1 ± 1.1) compared to 70% (11.3 ± 0.6) and 90% (13.0 ± 0). No differences were observed between 70%BFR (14.6 ± 0.6) and non-BFR conditions. CONCLUSION: This study demonstrated that cycling with the addition of BFR at an intensity equivalent to 70% of VT may provide a balance between physiological strain and perceived exertion.

Addition of blood flow restriction to passive mobilization reduces the rate of muscle wasting in elderly patients in the intensive care unit: a within-patient randomized trial

Objective: To evaluate the addition of blood flow restriction to passive mobilization in patients in the intensive care unit. Design: The study was a within-patient randomized trial. Setting: Two intensive care units in Belém, from September to October 2017. Subjects: In total, 34 coma patients admitted to the intensive care unit sector, and 20 patients fulfilled the study requirements. Interventions: All participants received the passive mobilization protocol for lower limbs, and blood flow restriction was added only for one side in a concurrent fashion. Intervention lasted the entire patient’s hospitalization time. Main outcome measurement: Thigh muscle thickness and circumference. Results: In total, 34 subjects were enrolled in the study: 11 were excluded for exclusion criteria, 3 for death, and 20 completed the intervention (17 men and 3 women; mean age: 66 ± 4.3 years). Despite both groups presented atrophy, the atrophy rate was lower in blood flow restriction limb in relation to the control limb (–2.1 vs. –2.8 mm, respectively, in muscle thickness; P = 0.001). In addition, the blood flow restriction limb also had a smaller reduction in the thigh circumference than the control limb (–2.5 vs. –3.6 cm, respectively; P = 0.001). Conclusion: The use of blood flow restriction did not present adverse effects and seems to be a valid strategy to reduce the magnitude of the rate of muscle wasting that occurs in intensive care unit patients.