Blood Flow Restriction Resistance Exercise Research Articles

Effects of Blood Flow Restricted Resistance Exercise on Recovery Blood Flow under Various Environmental Temperature Conditions

OBJECTIVES This study examines the impact of blood flow restriction (BFR) resistance exercise on blood flow across varying environmental temperatures, aiming to understand the physiological responses, exercise function, and recovery process affected by temperature changes.METHODS Seven healthy males (age: 26.4±1.7 years, weight: 72.7±6.8 kg, height: 174.5±2.0 cm) participated in biceps brachii exercises with and without BFR under low (10°C/25% humidity), moderate (25°C/50% humidity), and high (40°C/50% humidity) environmental conditions. Each participant completed six sessions of exercise across these conditions to assess the recovery phase blood flow changes. Blood flow measurements were taken during the recovery phase for analysis.RESULTS Blood flow significantly increased in high-temperature conditions, independent of BFR application, showing notable differences compared to low-temperature conditions (<i>p</i><.05).CONCLUSIONS Environmental temperature significantly affects blood flow changes during BFR resistance exercise, with increased blood flow in high temperatures indicating a physiological adaptation to thermal stress. This suggests the need to consider environmental temperatures in optimizing BFR exercise protocols.

Hypoalgesia and Conditioned Pain Modulation in Blood Flow Restriction Resistance Exercise.

We compared the magnitude of exercise-induced hypoalgesia and conditioned pain modulation between blood-flow restriction (BFR) resistance exercise (RE) and moderate-intensity RE. Twenty-five asymptomatic participants performed unilateral leg press in two visits. For moderate-intensity RE, subjects exercised at 50% 1RM without BFR whereas BFR RE exercised at 30% 1RM with a cuff inflated to 60% limb occlusion pressure. Exercise-induced hypoalgesia was quantified by pressure pain threshold changes before and after RE. Conditioned pain modulation was tested using cold water as the conditioning stimulus and mechanical pressure as the test stimulus and quantified as pressure pain threshold change. Difference in conditioned pain modulation pre- to post- RE was then calculated. The differences of RE on pain modulations were compared using paired t-tests. Pearson's r was used to examine the correlation between exercise-induced hypoalgesia and changes in conditioned pain modulation. We found greater hypoalgesia with BFR RE compared to moderate-intensity RE (p = 0.008). Significant moderate correlations were found between exercise-induced hypoalgesia and changes in conditioned pain modulation (BFR: r = 0.63, moderate-intensity: r = 0.72). BFR RE has favorable effects on pain modulation in healthy adults and the magnitude of exercise-induced hypoalgesia is positively correlated with conditioned pain modulation activation.

Acute hypoalgesic, neurophysiological and perceptual responses to low-load blood flow restriction exercise and high-load resistance exercise.

This study compared the acute hypoalgesic and neurophysiological responses to low-load resistance exercise with and without blood flow restriction (BFR), and free-flow, high-load exercise. Participants performed four experimental conditions where they completed baseline measures of pain pressure threshold (PPT), maximum voluntary force (MVF) with peripheral nerve stimulation to determine central and peripheral fatigue. Corticospinal excitability (CSE), corticospinal inhibition and short interval intracortical inhibition (SICI) were estimated with transcranial magnetic stimulation. Participants then performed low-load leg press exercise at 30% of one-repetition maximum (LL); low-load leg press with BFR at 40% (BFR40) or 80% (BFR80) of limb occlusion pressure; or high-load leg press of four sets of 10 repetitions at 70% one-repetition maximum (HL). Measurements were repeated at 5, 45min and 24h post-exercise. There were no differences in CSE or SICI between conditions (all P>0.05); however, corticospinal inhibition was reduced to a greater extent (11%-14%) in all low-load conditions compared to HL (P<0.005). PPTs were 12%-16% greater at 5min post-exercise in BFR40, BFR80 and HL compared to LL (P≤0.016). Neuromuscular fatigue displayed no clear difference in the magnitude or time course between conditions (all P>0.05). In summary, low-load BFR resistance exercise does not induce different acute neurophysiological responses to low-load, free-flow exercise but it does promote a greater degree of hypoalgesia and reduces corticospinal inhibition more than high-load exercise, making it a useful rehabilitation tool. The changes in neurophysiology following exercise were not related to changes in PPT.

Refining safety considerations for intradialytic blood flow restriction exercise. Commentary on “Concerns on the application of blood-flow restriction resistance exercise and thrombosis risk in hemodialysis patients”

Refining safety considerations for intradialytic blood flow restriction exercise. Commentary on “Concerns on the application of blood-flow restriction resistance exercise and thrombosis risk in hemodialysis patients”

Efficacy of Low Blood Flow Restricted Exercise on Increasing Muscle Strength in Patients with Knee Osteoarthritis Comparing with Conventional Strength Training

Background: The prevalence of OA knee is diagnosed with radiographic features 15% of patients were symptomaticin one study. OA affects nearly 6% of adults. Female sex is more common. 13% of females and 10% of male in 60years are affected with OA and in 70 years of population rises to 40%.Purpose: To find the efficacy of low blood flow restricted resistance exercise on increasing muscle strength inpatients with knee OA compared with conventional strength training using NPRS for pain and knee ROM.Materials and Methods: A total of 60 subjects were assigned in this study. The NPRS and knee ROM were usedto calculate pre-and post-test results. Each session included three sets of five repetitions with a ten-second hold inbetween. The tables were tabulated and statistically evaluated.The entire process was conducted from November2022 to April 2023.Result: According to the statistical analysis, both groups had a statistically significant improvement between theirpre and post-exercise values (p&lt;0.0001). There is also a significant variation in post-exercise results between thetwo groups (p&lt;0.0001), indicating that blood flow restriction with exercises is more effective than conventionalstrength training with exercises.Conclusion: Blood flow restriction has been shown to be more effective than conventional strength training atrelieving pain and increasing knee ROM.

Physiological and clinical effects of low-intensity blood-flow restricted resistance exercise compared to standard rehabilitation in adults with knee osteoarthritis–Protocol for a randomized controlled trial

Introduction Osteoarthritis (OA) is a common disease with high socioeconomical costs. In Denmark, standard rehabilitation (SR) consists of a combination of patient education and supervised physical exercise involving a standardized neuromuscular training program. As an evidence-based alternative, high–load (&gt;70% 1RM) resistance training (HIRT) has shown positive rehabilitation effects in knee-OA but may not be tolerated in all patients (~25%) due to knee joint pain. However, low-load resistance training (20–40% 1RM) with concurrent partial blood-flow restriction (BFR) appears to produce effects similar to HIRT yet involving reduced joint pain during and after exercise. The aim is to examine the effect of low-load BFR training compared to SR on pain, thigh muscle mass and muscle function in adults with knee-OA. We hypothesize that 12 weeks of BFR will lead to superior improvements in pain, muscle mass and mechanical muscle function compared to SR. Methods and analysis 90 participants diagnosed with radiographic knee-OA will be randomized to either BFR or SR twice a week for 12 weeks. BFR will consist of two selected lower limb strength exercises performed with an inflated pneumatic occlusion cuff. Intervention procedures in SR consist of a full 8 weeks GLA:D course followed by 4 weeks of team group training. Primary outcome variable is the change in KOOS-Pain subscale from baseline to 12 weeks. Secondary outcome variables are changes in pain sensitivity, functional performance, muscle mass and mechanical muscle function. Intention-to-treat and per-protocol analyses will be conducted. One-way analysis of variance will be performed to evaluate between-group changes. Pre-to-post intervention comparisons will be analyzed using a mixed linear model. Regression analysis will be performed to evaluate potential associations between selected outcome variables.

Autoregulated and Non-Autoregulated Blood Flow Restriction on Acute Arterial Stiffness.

This study aimed to investigate the acute effects of autoregulated and non-autoregulated applied pressures during blood flow restriction resistance exercise to volitional fatigue on indices of arterial stiffness using the Delfi Personalized Tourniquet System. Following a randomized autoregulated or non-autoregulated blood flow restriction familiarization session, 20 physically active adults (23±5 years; 7 females) participated in three randomized treatment-order sessions with autoregulated and non-autoregulated and no blood flow restriction training. Participants performed four sets of dumbbell wall squats to failure using 20% of one repetition maximum. Blood flow restriction was performed with 60% of supine limb occlusion pressure. Testing before and post-session included an ultrasonic scan of the carotid artery, applanation tonometry, and blood pressure acquisition.Carotid-femoral pulse wave velocity increased in the non-autoregulated and no blood flow restriction training groups following exercise while carotid-radial pulse wave velocity increased in the no blood flow restriction training group (all p<0.05). Carotid-femoral pulse wave velocity exhibited an interaction effect between autoregulated and non-autoregulated blood flow restriction in favor of autoregulated blood flow restriction (p<0.05). Autoregulated blood flow restriction training does not influence indices of arterial stiffness while non-autoregulated and no blood flow restriction training increases central stiffness.

Hormonal, immune, and oxidative stress responses to blood flow-restricted exercise.

Heavy-load free-flow resistance exercise (HL-FFRE) is a widely used training modality. Recently, low-load blood-flow restricted resistance exercise (LL-BFRRE) has gained attention in both athletic and clinical settings as an alternative when conventional HL-FFRE is contraindicated or not tolerated. LL-BFRRE has been shown to result in physiological adaptations in muscle and connective tissue that are comparable to those induced by HL-FFRE. The underlying mechanisms remain unclear; however, evidence suggests that LL-BFRRE involves elevated metabolic stress compared to conventional free-flow resistance exercise (FFRE). The aim was to evaluate the initial (<10 min post-exercise), intermediate (10-20 min), and late (>30 min) hormonal, immune, and oxidative stress responses observed following acute sessions of LL-BFRRE compared to FFRE in healthy adults. A systematic literature search of randomized and non-randomized studies was conducted in PubMed, Embase, Cochrane Central, CINAHL, and SPORTDiscus. The Cochrane Risk of Bias (RoB2, ROBINS-1) and TESTEX were used to evaluate risk of bias and study quality. Data extractions were based on mean change within groups. A total of 12525 hits were identified, of which 29 articles were included. LL-BFRRE demonstrated greater acute increases in growth hormone responses when compared to overall FFRE at intermediate (SMD 2.04; 95% CI 0.87, 3.22) and late (SMD 2.64; 95% CI 1.13, 4.16) post-exercise phases. LL-BFRRE also demonstrated greater increase in testosterone responses compared to late LL-FFRE. These results indicate that LL-BFRRE can induce increased or similar hormone and immune responses compared to LL-FFRE and HL-FFRE along with attenuated oxidative stress responses compared to HL-FFRE.

Effect of Blood Flow Restriction Resistance Exercise in Twenties on Biceps Activity, Fatigue and Hemodynamic Variables

Effect of Blood Flow Restriction Resistance Exercise in Twenties on Biceps Activity, Fatigue and Hemodynamic Variables

Investigating the autoregulation of applied blood flow restriction training pressures in healthy, physically active adults: an intervention study evaluating acute training responses and safety

ObjectiveTo examine the effects of autoregulated (AUTO) and non-autoregulated (NAUTO) blood flow restriction (BFR) application on adverse effects, performance, cardiovascular and perceptual responses during resistance exercise.MethodsFifty-six healthy participants underwent AUTO...

ACUTE EFFECT OF BLOOD FLOW RESTRICTED RESISTANCE EXERCISE ON IRISIN AND SEX HORMONES

Purpose: The relationship between exercise and irisin and sex hormone release is unclear and is of interest to current research. This study aimed to investigate the acute effect of blood flow restricted (BFR) resistance exercise on irisin and sex hormones.&#x0D; Material and Methods: The study included healthy males over 18 years of age. Participants' physical activity levels were determined using International Physical Activity Questionnaire (IPAQ). Participants underwent body composition analysis and isotonic muscle strength measurement and were randomly divided into 3 groups: low-intensity (20% of 1-RM) resistance exercise with BFR, high-intensity (70% of 1-RM) resistance exercise without BFR, and a control group. Blood samples were obtained 15 minutes post-exercise to assess acute irisin, testosterone, and estrogen responses.&#x0D; Results: The study included 17 healthy males. The average age was 26.1±2.9 years, mean physical activity was 1259.2±1003.1 MET/week, and mean 1-RM max (as measured with isotonic muscle strength test) was 41.1±7.5 kg. The descriptive characteristics of the three groups were statistically similar (p&gt;0.05). The acute post-intervention irisin and sex hormone levels were not statistically different between the groups (p&gt;0.05).&#x0D; Conclusion: Acute changes in irisin and sex hormone levels were not statistically different for low-intensity BFR and high-intensity non-BFR exercise.

Effects of Sex and Cuff Pressure on Physiological Responses during Blood Flow Restriction Resistance Exercise in Young Adults.

The purpose of this study was to examine the physiological responses resulting from an acute blood flow restriction resistance exercise bout with two different cuff pressures in young, healthy men and women. Thirty adults (18-30 yr) completed a bilateral leg extension blood flow restriction bout consisting of four sets (30-15-15-15 repetitions), with cuffs applied at pressures corresponding to 40% and 60% of the minimum arterial occlusion pressure (AOP) needed to completely collapse the femoral arteries. During each of these conditions (40% and 60% AOP), physiological measures of near-infrared spectroscopy (NIRS) and EMG amplitude (EMG AMP) were collected from the dominant or nondominant vastus lateralis. After each set, ratings of perceived exertion (RPE) were collected, whereas only at baseline and at the end of the bout, mean arterial pressure (MAP) was assessed. Separate mixed-factorial ANOVA models were used to examine mean differences in the change in EMG AMP and NIRS parameters during each set. The absolute RPE and MAP values were also examined with separate ANOVAs. A P value ≤0.05 was considered statistically significant. Regardless of sex or cuff pressure, the change in EMG AMP was lower in set 1 (14.8%) compared with the remaining sets (22.6%-27.0%). The 40% AOP condition elicited the greatest changes in oxy[heme] and deoxy[heme], while also providing lower RPEs. For MAP, there was an effect for time such that MAP increased from preexercise (87.5 ± 4.3 mm Hg) to postexercise (104.5 ± 4.1 mm Hg). The major findings suggested that the 40% AOP condition permitted the greatest amount of recovery during the interset rest. In addition, there did not seem to be any meaningful sex-related difference in this sample of young healthy adults.

A Comparison between High and Low Cuff Pressures on Muscle Oxygen Saturation and Recovery Responses Following Blood-Flow Restriction Resistance Exercise.

The aim of the study was to compare the recovery response and muscle oxygenation of a blood-flow restriction resistance exercise (BFR) session with high [HP: 80% of the arterial occlusion pressure (AOP)] and low cuff pressure (LP: 40% of AOP). Both exercise sessions included 4 sets to failure at the barbell preacher curl exercise. Twelve resistance trained men (27.4 ± 5.0 years; 83.5 ± 11.6 kg; 176.6 ± 7.0 cm) performed each protocol in a counterbalanced, randomized order. Maximal isometric force, muscle morphology and muscle soreness of the biceps brachii muscle were assessed at baseline, 15-min, 60-min and 24-h post each testing session. In addition, muscle oxygen saturation (SmO2) was assessed during each training session. A lower number of repetitions (p = 0.013) was detected in HP compared to LP. A lower SmO2 (p < 0.001) was detected in the recovery time between the sets in HP (mean: 47.6 ± 15.7%) compared to LP (mean: 68.9 ± 7.2%). No differences between the two trials (p > 0.05) were noted for isometric force, muscle architecture and soreness at any timepoint. Results indicate that, despite a high cuff pressure may induce a more hypoxic condition compared to a lower cuff pressure, recovery responses may not be affected.

Caffeine Abstinence In Habituated Users: Cardiovascular And Perceptual Responses To Exercise With Blood Flow Restriction

Studies using blood flow restriction resistance exercise (BFR-RE) often require caffeine abstinence. For habitual users,effects may be attenuated, and it is unknown if abstinence alters responses to BFR-RE. PURPOSE: Compare cardiovascular and perceptual responses to BFR-RE when habitual users consume or abstain from caffeine. METHODS: 15 participants completed a 3 visit within-subject study beginning with a one repetition maximum (1RM) test and caffeine intake assessment. Visits 2-3 consisted of dominant arm BFR-RE [3 sets of bicep curls to failure with 30% 1RM, 40% arterial occlusion pressure (AOP), 30s inter-set rest]. Visits 2-3 were 1h after typical dose, one with caffeine (CAFF) and one without (ABS) (counterbalanced). Heart rate (HR), systolic (SBP) and diastolic (DBP) BP, and AOP were measured pre- and post-exercise and ratings of perceived exertion (RPE-E) and discomfort (RPE-D) after each set. Exercise volume(VOL) per set was calculated as load (kg) x repetitions. Bayesian RMANOVA were used to find the most probable model for SBP, DBP, HR and AOP (results are mean ± SD). BF10 = most probable alternative model vs. the null. Bayesian paired t-tests were used to compare RPE-E, RPE-D, and VOL for each set (results are mean difference ± SD). RESULTS: Main effects of time and condition for SBP (mmHg, BF10 = 895.4) and DBP (mmHg, BF10 = 481.6) indicated CAFF (SBP = 118.4 ± 10.9, DBP = 82.3 ± 10.4) was greater than ABS (SBP = 114.6 ± 10.6, DBP = 79.2 ± 9.9), and post (SBP =119.9 ± 11.0, DBP = 8.6 ± 11.4) was greater than pre (SBP = 113.1 ± 9.6, DBP = 76.93 ± 7.1). A main effect of time indicated AOP (mmHg, BF10 = 10390.7) increased pre (134.5 ± 16.5) to post (150.5 ± 20.6). A main effect of time indicated HR (bpm, BF10 = 50.5) increased pre (80.1 ± 10.1) to post (87.7 ± 14.0). Moderate evidence indicated no difference in RPE-E (AU) between CAFF and ABS for set 1 (0.0 ± 0.9, BF10 = .3) and anecdotal evidence for sets 2 (0.3 ± 1.2) and 3 (-0.3 ± 1.2, BF10 both ≤.4). Anecdotal evidence indicated no difference in RPE-D (AU) between CAFF and ABS for sets 1 (0.0 ± 1.2), 2 (0.3 ± 1.9), and 3 (-0.4 ± 1.7, BF10 all ≤.4). Anecdotal evidence indicated no difference in VOL (AU) for sets 1 (6.1 ± 24.4), 2 (-0.2 ± 10.6), and 3 (-0.5 ± 7.3, BF10 all ≤.4). CONCLUSION: In habitual users, caffeine may increase BP, but other cardiovascular and perceptual responses to BFR-RE may not be impacted.

Resting Myokine Concentrations Are Reduced With Resistance-exercise Training But Blood Flow-restricted Resistance-exercise Response Is Unchanged.

Myokines are proteins and peptides produced and secreted by skeletal muscle; some are postulated to contribute to skeletal muscle hypertrophy. PURPOSE: To evaluate systemic myokine concentrations following acute blood-flow restricted resistance-exercise (BFR-RE) after a twelve-week traditional strength-training protocol in younger and older males. METHODS: Untrained males (younger: 24.7 ± 3.9 yrs, n = 8; older: 68.3 ± 4.6 yrs, n = 7) performed full-body BFR-RE before and after 12 weeks of progressive full-body strength training. At rest, immediately after, and 3, 6, 24 and 48 hours following each BFR-RE session, venous blood was collected and analyzed in duplicate to determine concentrations of interleukin-4 (IL-4), IL-6, IL-7, irisin, Leukemia Inhibitory Factor (LIF) and nitrate/nitrite. Area under the curve was calculated and a 2-way (age × training status) repeated measures ANOVA was conducted. RESULTS: For older males, IL-4 (untrained = 6996.9 ± 9260.2 AUC vs. trained = 5681.2 ± 8133.6 AUC; p = 0.038) and IL-6 (untrained = 819.2 ± 1104.5 AUC vs. trained = 636.5 ± 952.8 AUC; p = 0.016) were higher in the untrained condition than trained but did not differ for younger males. A significant age effect was identified for irisin, as younger males had higher concentrations than older (mean difference = 9423.8 ± 12546.8 AUC; p = 0.012). However, when AUC was calculated with baseline values subtracted, participants had higher IL-7 in the untrained condition compared to trained (mean difference = 33.5 ± 56.9 AUC; p = 0.04). Other myokines showed no training differences. CONCLUSION: Younger males had higher circulating irisin, and strength training decreased IL-4 and IL-6 in older males. The disappearance of age-related changes in IL-4 and IL-6 after baseline subtraction suggests those differences were due to lower baseline concentrations following the strength training program. Thus, IL-4 and IL-6 levels did not respond differently to BFR-RE in the untrained and trained conditions. Also, the lower response of IL-7 to BFR-RE in the trained vs. the untrained condition indicates that myokine secretion is affected by an individual’s level of training. Funding: This project was supported by grants (SMC & JEA) from the University Collaborative Research Program and Faculty of Science Collaborative - University of Manitoba.

Cardiometabolic Disease Risk in Normal Weight Obesity and Exercise Interventions for Proactive Prevention

PURPOSE: Normal weight obesity (NWO) is characterized by a normal body mass index but a high body fat mass percentage and low skeletal muscle mass, thereby increasing the risk of cardiometabolic dysfunction and morbidity. However, the effects of exercise intervention in reducing the risk of cardiometabolic disease in NWO have not been fully elucidated. Therefore, this review aimed to summarize the potential cardiometabolic disease risk and to provide implications of exercise interventions for the proactive prevention of cardiometabolic disease risk in NWO.METHODS: We searched and summarized the literature on the cardiometabolic risk factors in NWO. In addition, we summarized literature investigating the effects of exercise intervention on the cardiometabolic risk factors in NWO. We performed the literature search using PubMed, Web of Science, and Google Scholar databases.RESULTS: NWO was associated with increased visceral fat, ectopic fat, oxidative stress, inflammatory cytokines, insulin resistance, dyslipidemia, and subclinical atherosclerosis compared with normal weight lean. NWO requires exercise interventions that induce alterations in body composition, such as decreased body fat percentage and increased muscle mass. Resistance exercise (RE) and high-intensity interval exercise (HIIE) can improve lipid components and alter body composition in NWO. In addition, low-intensity blood flow restriction resistance exercise (BFR-RE) may enhance muscular strength and anaerobic power in NWO.CONCLUSIONS: The cardiometabolic disease risk is increased in NWO. We suggest that exercise interventions (RE, HIIE, and BFR-RE) may effectively prevent cardiometabolic disease risk and alter body composition in NWO. As this has potential implications for exercise interventions in NWO, further investigations are needed to find the optimal exercise for proactive prevention of cardiometabolic risk in NWO.

Myokine Response to Blood-Flow Restricted Resistance Exercise in Younger and Older Males in an Untrained and Resistance-Trained State: A Pilot Study

PurposeThe purpose of this study was to examine the response of myokines to blood-flow restricted resistance-exercise (BFR-RE) in younger and older males before and after completing a 12-week resistance-training program.MethodsThere were 8 younger (24.8 ± 3.9 yrs) and 7 older (68.3 ± 5.0 yrs) untrained male participants completed this study. Anthropometric and maximal strength (1RM) measurements were collected before and after a 12-week, supervised, progressive full-body resistance-training program. As well, an acute bout of full-body BFR-RE was performed with venipuncture blood samples collected before and immediately following the BFR-RE, followed by sampling at 3, 6, 24 and 48 h.ResultsThe 12-week training program stimulated a 32.2% increase in average strength and 30% increase in strength per kg of fat free mass. The response of particular myokines to the acute bout of BFR-RE was influenced training status (IL-4, untrained = 78.1 ± 133.2 pg/mL vs. trained = 59.8 ± 121.6 pg/mL, P = 0.019; IL-7, untrained = 3.46 ± 1.8 pg/mL vs. trained = 2.66 ± 1.3 pg/mL, P = 0.047) or both training and age (irisin, P = 0.04; leukemia inhibitory factor, P < 0.001). As well, changes in strength per kg of fat free mass were correlated with area under the curve for IL-4 (r = 0.537; P = 0.039), IL-6 (r = 0. 525; P = 0.044) and LIF (r = − 0.548; P = 0.035) in the untrained condition.ConclusionThis study identified that both age and training status influence the myokine response to an acute bout of BFR-RE with the release of IL-4, IL-6 and LIF in the untrained state being associated with changes in strength per kg of fat free mass.

Effect of supervised rehabilitation combined with blood flow restriction training in athletes with chronic ankle instability: a randomized placebo-controlled trial.

Blood flow restriction (BFR) resistance exercise has been advocated as an alternative approach for improving muscle strength in patients undergoing musculoskeletal rehabilitation. The present study aimed to evaluate the effectiveness of a 4-week supervised rehabilitation (R) with and without BFR on muscle strength, cross-sectional area (CSA), dynamic balance, and functional performance in athletes with chronic ankle instability (CAI). A total of 16 collegiate athletes with CAI participated in this study. They were randomly assigned to the BFR+R group (n=8) or the R group (n=8). Both groups underwent supervised rehabilitation 3 times weekly for 4 consecutive weeks. Additionally, the BFR+R group was applied with a cuff around the proximal thigh at 80% arterial occlusion pressure in addition to the traditional rehabilitation program, whereas the R group received the sham BFR only. Before and after 4 weeks of intervention, isokinetic muscle strength, CSA, Y-balance test, and side hop test (SHT) were measured. Following a 4-week intervention, the BFR+R group exhibited significant improvements in muscle strength of ankle plantarflexor and evertor, CSA of fibularis longus, and SHT timed performance compared with prior training and the R group (all, P<0.05). However, no significant difference was observed on dynamic balance among the groups. The present finding indicated that a 4-week supervised rehabilitation combined with BFR is more effective in improving muscle strength and size and functional performance compared with the traditional rehabilitation alone. This information could have implications for physical therapists and clinician in developing and designing a rehabilitation program for athletes with CAI.

Neuromuscular Impact of Acute Hypertrophic Resistance Loading With and Without Blood-Flow Restriction

Exploring acute neuromuscular fatigue induced by different modalities of resistance exercise would help understand the adaptation subsequent to specific training programs. Therefore, we investigated the acute impact of high-intensity and low-intensity blood flow-restricted resistance exercise on the development of explosive torque throughout the torque-time curve. Seventeen healthy, young participants were included in a randomized, counterbalanced within-subjects design study, in which participants underwent two experimental conditions, separated by a 1-wk period. Low-intensity blood-flow restricted exercise and high-intensity resistance exercise were performed using dynamic elbow flexion at 20 and 75% of 1 repetition maximum, respectively. Maximal voluntary contraction (MVC) and the sequential rate of torque development (absolute and relative) were measured before and after exercise. Both protocols elicited a similar decrement in MVC (~ 25%) and in the peak rate of torque development after exercise (~ 45%). The absolute rate of torque development (0-50 and 50-100 ms) was also reduced (p<0.05) similarly between conditions. After normalizing torque values to MVC, this was only sustained for the rate of torque development 0-50ms (p<0.05). We found that both exercise protocols induced similar acute attenuation of the absolute rate of torque development up to the first 100 ms of MVC. We also demonstrated that the reduction in the rate of torque development between 50-100ms (in both protocols) was largely explained by an acute deficit in muscle strength post-exercise. Conversely, the impact of each protocol on the first 50ms of muscle torque did not depend on lower levels of muscle strength after exercise.

The Role of Plasma Extracellular Vesicles in Remote Ischemic Conditioning and Exercise-Induced Ischemic Tolerance.

Ischemic conditioning and exercise have been suggested for protecting against brain ischemia-reperfusion injury. However, the endogenous protective mechanisms stimulated by these interventions remain unclear. Here, in a comprehensive translational study, we investigated the protective role of extracellular vesicles (EVs) released after remote ischemic conditioning (RIC), blood flow restricted resistance exercise (BFRRE), or high-load resistance exercise (HLRE). Blood samples were collected from human participants before and at serial time points after intervention. RIC and BFRRE plasma EVs released early after stimulation improved viability of endothelial cells subjected to oxygen-glucose deprivation. Furthermore, post-RIC EVs accumulated in the ischemic area of a stroke mouse model, and a mean decrease in infarct volume was observed for post-RIC EVs, although not reaching statistical significance. Thus, circulating EVs induced by RIC and BFRRE can mediate protection, but the in vivo and translational effects of conditioned EVs require further experimental verification.