Low-intensity Blood Flow Restriction Research Articles

Are calves trainable? Low-intensity calf muscle training with or without blood flow restriction: a randomized controlled trial

Abstract Objectives Whether low-load resistance training (RT) without muscle failure, with or without blood flow restriction (BFR), is sufficient to increase strength and muscle growth of calf muscles in trained individuals is still unclear. This study aimed to compare the effects of low-intensity BFR RT vs. traditional low-intensity RT (noBFR) with moderate training volume on strength and circumference. Methods We designed a parallel, randomized controlled trial including 36 RT-trained participants (BFR: 7 females, 32.9 ± 8.8 years, 11 males, 28.4 ± 3.6 years; noBFR; 8 females, 29.6 ± 3.4 years; 10 males, 28.6 ± 4.9 years) who underwent eight weeks of twice-weekly low-load RT with 16 weekly RT sets (30 % of one-repetition maximum [1RM]). RT consisted of bilateral calf raises and seated unilateral calf raises, each conducted with 4 sets (30, 15, 15, 15 repetitions not to failure) of either BFR or noBFR. Outcome measures included calf circumference (CC), leg stiffness (LS), and various strength tests (seated and standing calf raise 1RM, isokinetic strength of plantar- and dorsiflexion). Results There were no significant interactions or group effects for most measures. Both groups showed significant improvements in seated calf raise strength (p=0.046, η 2 p=0.17). Pairwise comparisons indicated moderate to large effect sizes for strength improvements (standardized mean differences: 0.35–1.11), but no changes in calf circumference were observed in either group. Conclusions Low-load RT with and without BFR are useful to increase strength without necessarily affecting hypertrophy. Low-intensity BFR training did not confer additional benefits over traditional low-intensity RT for calf muscle strength or circumference, questioning its general advantage under such conditions.

Comparison of Adaptations in the Gastrocnemius Muscle from an Exercise Program with and without Low-Intensity Blood Flow Restriction Banding in 18 Male Amateur Basketball Players Aged 16-45 Years.

BACKGROUND Basketball is a sport with a global impact and recognized major leagues, and is one of the most studied and analyzed sports for improvement at the level of the high-performance athlete. Increasing the jump height of basketball players is an essential factor for high athletic performance. MATERIAL AND METHODS This study aimed to identify the effect of low-intensity training with flow restriction versus the eccentric exercise protocol on amateur athletes. Eighteen amateur basketball players aged 16-45 years were divided into 2 groups: Group A consisted of 9 participants with low-intensity training with flow restriction (40% intensity) with 200 mmHg occlusion applying flow restriction bands in the popliteal area, while Group B consisted of 9 participants who performed an eccentric exercises protocol on the gastrocnemius. An anthropometric evaluation was applied, which consisted of perception of effort, range of movement (ROM), muscle strength intensity, and the power of the jump measured with a jump platform. RESULTS Notable changes were observed in favor of Group A for the right dorsiflexion, with mean difference (MD)=-2.444 (P=0.018); left dorsiflexion with MD=-2.778 (P=0.027) and left foot perimeter variable with MD=-0.667 (P=0.026) at 95% confidence interval (CI); while the vertical jump was in favor of Group B, with MD=-2.899 (P=0.006). CONCLUSIONS Low-intensity training with flow restriction and eccentric exercise protocol were both effective in improving jumping performance. A significant improvement was shown in the jump height and ROM of the 2 study groups.

WALKING WITH BLOOD FLOW RESTRICTION: A NOVEL METHOD TO IMPROVE PHYSICAL FITNESS IN OLDER ADULTS?

INTRODUCTION AND AIMS Alternative physical activity modalities and methods are needed to combat low adherence among older populations. Therefore, we are investigating whether blood flow restricted (BFR) walking improves measures of lower limb strength, and functional performance, compared to traditional walking in older adults. METHODS Healthy adults ≥60 years were randomised into BFR (n=5) or non-BFR (n=4) walking groups. Both groups walked outdoors, 3 days/week for 12 weeks starting at 4km/h and increasing walking speed by 0.5km/h every 4 weeks. The BFR group walked for 25min with BFR applied (60% arterial occlusion pressure) to the lower limbs in 2x 10mins bouts (separated by 5mins walking without occlusion). The non-BFR group walked for 50mins without occlusion, matching current best practice for low-moderate intensity physical activity. Participants were assessed at baseline and post-intervention (12 weeks) for knee extension maximal voluntary torque (MVTpeak) and functional capacity (four square step test [4SST], 5x sit-to-stand [STS], timed up and go [TUG], gait speed, and 6-minute walk test [6mWT]). RESULTS There were no differences at baseline between groups (p>0.05). Both groups improved across all measures from baseline to post-intervention, with significant effects for time observed for: 4SST (7.92±1.2s – 6.83±1.39s; p=0.035), TUG (6.16±0.81s – 5.58±0.9s; p=0.04), STS (11.30±1.70s – 10.14±1.7s; p=0.032), but not for gait speed (3.98±0.69s – 3.71±0.69s; p=0.456), 6mWT (564.72±72.13m – 601.27±64.2m; p=0.129) and MVTpeak (112.33±25.8Nm – 120.55±23.5Nm; p=0.995). No group x time effect was observed from baseline to 12 weeks (p>0.05). SUMMARY The current results demonstrate significant improvements in functional measures (4SST, TUG, STS) from baseline to post-intervention, with no differences observed between groups. This indicates that low-intensity BFR walking may provide comparable physical fitness improvements to non-BFR walking while completing only 50% of the volume.

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

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

Short-Term Impact of Low-Intensity Exercise with Blood Flow Restriction on Mild Knee Osteoarthritis in Older Adults: A Pilot Study

This pilot study aimed to investigate the immediate impact of low-intensity exercises with blood flow restriction (BFR) on older adults with knee osteoarthritis (KOA). Fifteen patients with KOA who were over 50 years old, participated and underwent low-intensity resistance knee exercises at 30% of their one-repetition maximum with BFR three times/week for two weeks. Pre- and post-exercise assessments included pain levels, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores, isokinetic knee strength, lower extremity muscle volume (via leg circumference and muscle thickness), functional performance tests (timed up-and-go [TUG] and sit-to-stand [STS]), skeletal muscle index (SMI) using bioelectrical impedance analysis, and handgrip strength (HGS). Post-exercise, there was a significant reduction in pain. WOMAC scores showed significant improvements across all three domains: pain, stiffness, and physical function. In the TUG and STS tests, completion times were significantly reduced. Thigh and calf circumferences, as well as thigh muscle thickness significantly increased after exercise. Post-exercise SMI and HGS also significantly increased. However, isokinetic knee strength did not show significant changes. In conclusion, low-intensity BFR exercises provide immediate benefits in symptoms and physical performance for patients with KOA, potentially inducing local and systemic muscle mass increase, even after a short-term intervention.

Blood Flow Restriction Training Improves Muscular Outcomes in Patients With Chronic Ankle Instability: A Critically Appraised Topic

Clinical Scenario: The high recurrence of lateral ankle sprains progresses to chronic ankle instability (CAI) and can affect many athletes in all sports. CAI is often associated with a decrease in muscle strength, an increase in pain, a decrease in the range of motion, and a decrease in balance or neuromuscular control. The use of blood flow restriction (BFR) with CAI can increase muscular outcomes and be used as a rehabilitation tool. Clinical Question: Is there evidence to suggest that BFR improves strength, muscle activation, and/or cross-sectional area of the lower leg musculature in those with CAI? Clinical Bottom Line: There is moderate evidence to support therapeutic exercise with low-intensity BFR in patients with CAI. The evidence concluded a significant improvement in BFR to increase muscle activation of the fibularis longus, anterior tibialis, vastus lateralis, and soleus. There is moderate evidence suggesting BFR can induce strength gains in the muscles of the lower extremity in patients with CAI. Strength of Recommendation: The comprehensive evidence is a Strength of Recommendation Taxonomy (SORT) Grade B, with a level of evidence of 2, according to the Centre for Evidence-Based Medicine (CEBM) for the studies included.

Elevating athletic performance: Maximizing strength and power in long jumpers through combined low-intensity blood flow restriction and high-intensity resistance training

PurposeThis study aimed to evaluate the effects of low-intensity blood flow restriction (BFR) training and high-intensity resistance training (HI-RT) on the leaping performance of long-jumpers. Materials and methodsLong jump players were divided into two groups; one group (group A) receiving HI-RT (n = 8) and the other group (group B) receiving combined low-intensity BFR training plus HI-RT (n = 8). Muscle power and knee muscle strength was assessed at baseline, 3 weeks and 6 weeks of intervention. Results1-RM was found to be significantly different between Group A and Group B at 3 and 6 weeks. Further, IKDQR, IKDHR and IKDQL was significantly improved in group B as compared to group A both at 3 and 6 weeks. There was significant time effect, group effect and time-group interaction in the strength of quadriceps and hamstring of both left and right leg measured through isokinetic device. Post-hoc analysis for 1-RM in group B showed a significant improvement at baseline and 6 weeks and the broad jump was significant at baseline and 3 weeks and at baseline and 6 weeks. ConclusionThe combined effects of low-intensity BFR training and HI-RT is effective in improving the muscle strength and power of lower limbs in long jumpers.

Poster 328: Pre-Operative Low-Intensity Blood Flow Restriction Training Does Not Improve Quadriceps Strength or Hypertrophy After Anterior Cruciate Ligament Reconstruction

Objectives: The purpose of this study is to evaluate the effect of low-intensity blood flow restriction (LI- BFR) training utilized in a pre-rehabilitative setting for patients undergoing anterior cruciate ligament reconstruction (ACLR) on postoperative outcomes by minimizing postoperative atrophy and impairment of the quadriceps. We hypothesize that postoperative strength and hypertrophy of the quadriceps will be greater in a population that undergoes preoperative LI-BFR training than that of a population that undergoes low-intensity sham control (LI-SHAM) training. Methods: Twenty-eight subjects undergoing primary ACLR underwent 2 weeks of either a BFR intervention or a SHAM intervention at a rate of 2 sessions per week before surgery. Quadriceps strength and cross-sectional area were measured as well as other exploratory outcomes were measured before and after the intervention before surgery and at 5 different time points after surgery, through 6 months postoperative. Quadriceps strength was assessed through handheld dynamometry and a leg press test and quadriceps cross-sectional area was assessed using musculoskeletal ultrasound imaging. Results: Adjusting for sex, time, and strength/hypertrophy at baseline, there were no significant differences found between treatment groups for the primary endpoints. Compared to 24-48 hours pre- op, this suggests that the post-op average hypertrophy remains significantly lower through 24 weeks post-op, while leg strength is similar at 24 weeks post-op as measured by handheld dynamometer and even significantly larger at 24 weeks as measured by the leg press test. Conclusions: A 2-week preoperative program of LI-BFR training may not be effective to improve postoperative quadriceps strength and hypertrophy after ACLR.

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

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

Blood Flow Restricted Cycling Impairs Subsequent Jumping But Not Balance Performance Slightly More Than Non-Restricted Cycling: An Acute Randomized Controlled Cross-Over Trial.

Chronic blood flow restriction (BFR) training has been shown to improve drop jumping (DJ) and balance performance. However, the acute effects of low intensity BFR cycling on DJ and balance indices have not yet been examined. 28 healthy young adults (9 female; 21.8 ± 2.7years; 1.79 ± 0.08m; 73.9 ± 9.5kg) performed DJ and balance testing before and immediately after 20min low intensity cycling (40% of power at maximal oxygen uptake) with (BFR) and without BFR (noBFR). For DJ related parameters, no significant mode × time interactions were found (p ≥ 0.221, ηp 2 ≤ 0.06). Large time effects for DJ heights and the reactive strength index were observed (p < 0.001, ηp 2 ≥ 0.42). Pairwise comparison revealed notably lower values for both DJ jumping height and reactive strength index at post compared to pre (BFR: -7.4 ± 9.4%, noBFR: -4.2 ± 7.4%). No statistically significant mode × time interactions (p ≥ 0.36; ηp 2 ≤ 0.01) have been observed for balance testing. Low intensity cycling with BFR results in increased (p ≤ 0.01; SMD ≥ 0.72) mean heart rate (+14 ± 8bpm), maximal heart rate (+16 ± 12 bpm), lactate (+0.7 ± 1.2 mmol/L), perceived training intensity (+2.5 ± 1.6au) and pain scores (+4.9 ± 2.2au) compared to noBFR. BFR cycling induced acutely impaired DJ performance, but balance performance was not affected, compared to noBFR cycling. Heart rate, lactate, perceived training intensity, and pain scores were increased during BFR cycling.

Physiological adaptations and myocellular stress in short-term, high-frequency blood flow restriction training: A scoping review.

High frequency (1-2 times per day) low-intensity blood flow restriction (BFR) training has been recommended as a prescription approach for short durations of time to maximize relevant physiological adaptations. However, some studies demonstrate negative physiological changes after short periods of high-frequency BFR training, including prolonged strength decline and muscle fiber atrophy. To provide a comprehensive overview of short-term, high-frequency blood flow restriction training, including main adaptations, myocellular stress, limitations in the literature, and future perspectives. A systematic search of electronic databases (Scopus, PubMed®, and Web of Science) was performed from the earliest record to April 23, 2022. Two independent reviewers selected experimental studies that analyzed physical training protocols (aerobic or resistance) of high weekly frequency (>4 days/week) and short durations (≤3 weeks). In total, 22 studies were included in this review. The samples were composed exclusively of young predominantly male individuals. Muscle strength and hypertrophy were the main outcomes analyzed in the studies. In general, studies have demonstrated increases in strength and muscle size after short term (1-3 weeks), high-frequency low-intensity BFR training, non-failure, but not after control conditions (non-BFR; equalized training volume). Under failure conditions, some studies have demonstrated strength decline and muscle fiber atrophy after BFR conditions, accompanying increases in muscle damage markers. Significant limitations exist in the current HF-BFR literature due to large heterogeneities in methodologies. The synthesis presented indicates that short-term, high-frequency BFR training programs can generate significant neuromuscular adaptations. However, in resistance training to failure, strength declines and muscle fiber atrophy were reported. Currently, there are no studies analyzing low-frequency vs. high-frequency in short-term BFR training. Comparisons between resistance exercises of similar intensities (e.g., combined effort) are lacking, limiting conclusions on whether the effect is a product of proximity to failure or a specific effect of BFR.

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 Low Intensity Blood Flow Restriction Training on Muscle Volume, Strength and Power in Healthy Middle-Aged Females

OBJECTIVES The purpose of this study is to investigate the efficacy of weight training with controlled blood flow occlusion compared to conventional resistance training, in the ageing population.METHODS Twenty-three healthy female subjects (aged 40-55) were randomly assigned to one of three groups; low intensity blood flow restriction training (LI-BFRT) (n = 9), conventional resistance training (RT) (n = 7) and control (CON) (n = 7). The RT group trained between 65-70% one repetition maximum (1RM) and the LI-BFRT group trained at 30% 1RM while wearing pressure cuffs inflated to 100-120% of brachial systolic blood pressure (bSBP). Relative appendicular skeletal muscle mass (ASM/weight), isokinetic strength and power were tested pre and post 8 weeks of training.RESULTS Upper limb ASM/weight increased significantly in the LI-BFRT and RT groups (both p &lt; 0.001). Only LI-BFRT showed significant difference compared with the CON group (p &lt; 0.01). Lower limb ASM/weight improved in both the LI-BFRT (p &lt; 0.01) and CON (p &lt; 0.01) groups without group differences. Lower limb flexion strength increased in the LI-BFRT and RT groups (both p &lt; 0.01), with differences between groups (p &lt; 0.01, LI-BFRT &gt; RT &gt; CON). Only RT increased extension muscle strength (p &lt; 0.05). Lower limb flexion and extension power improved following LI-BFRT (p &lt; 0.05 and p &lt; 0.01, respectively), significantly greater than RT in both flexion (p &lt; 0.001) and extension (p &lt; 0.01).CONCLUSIONS LI-BFRT may be as, if not more effective than RT for increasing muscle volume, strength and power in middle-aged women.

The Impact Of Blood Flow Restriction Resistance Training On Pain Modulation In Pain Free Individuals

Blood flow restriction (BFR) resistance training (RT) is beneficial for enhancing muscle size and strength at low intensity and is effective and feasible in musculoskeletal rehabilitation. However, the effects of BFR RT on pain modulation remain unclear. PURPOSE: To evaluate the effects of low-intensity BFR and conventional moderate intensity (MI) RT on pain modulation in pain-free adults METHODS: Nineteen adults without current pain (10 M, mean age = 27 yrs., mean BMI = 23 kg/m2) participated in this study. Participants were screened for contraindications of BFR training (e.g., immobilization) and conditions that may influence pain modulation (e.g., neuropathy).A repeated measures design with counterbalanced order of RT conditions were applied. All participants completed two RT visits (MI or BFR) approximately 9 days apart. At each visit, dominant leg one-repetition maximum (1RM) was determined on a leg press machine after standardized warm-up. For both RT conditions, participants performed a unilateral leg press with the dominant leg. For MI, participants performed the unilateral leg press at 50% 1RM. For BFR RT, a 20-cm width cuff was placed at the proximal thigh during exercise. Participants performed the leg press at 30% 1RM with the cuff inflated to 60% limb occlusion pressure. Participants performed four sets of RT in each visit with a protocol of 30-15-15 repetitions at the first three sets and exercise to failure at the fourth set. Failure was defined as failing to maintain the form. A rate of two seconds per repetition was applied with a 30-second rest between sets. Pressure pain threshold (PPT) was measured over the rectus femoris immediately after exercise using a hand-held algometer. Exercise-induced hypoalgesia (EIH) was calculated as the change in PPT. Statistical Analysis: Paired t-tests (α = 0.05) and Cohen’s d for effect size were used to assess statistical significance. RESULTS: Mean (SD) baseline PPT was 46.6 N (15.2) and 45.2 N (10.4) at Visit 1 and Visit 2, respectively. Greater EIH was found with BFR compared to MI RT (31.23% vs. 14.21%, p = 0.039, d = 0.62) CONCLUSIONS: Low-intensity BFR RT elicited a greater EIH effect compared to MI RT in pain-free adults. Future studies are needed to evaluate mechanisms underlying EIH with RT and to extend this work to clinical populations

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.

Acute and Chronic Bone Marker and Endocrine Responses to Resistance Exercise With and Without Blood Flow Restriction in Young Men.

In this study, we compared acute and chronic bone marker and hormone responses to 6 weeks of low intensity (20% 1RM) blood flow restriction (BFR20) resistance training to high intensity (70% 1RM) traditional resistance training (TR70) and moderate intensity (45% 1RM) traditional resistance training (TR45) in young men (18–35 years). Participants were randomized to one of the training groups or to a control group (CON). The following training programs were performed 3 days per week for 6 weeks for knee extension and knee flexion exercises: BFR20, 20%1RM, 4 sets (30, 15, 15, 15 reps) wearing blood flow restriction cuffs around the proximal thighs; TR70, 70% 1RM 3 sets 10 reps; and TR45, 45% 1RM 3 sets 15 reps. Muscle strength and thigh cross-sectional area were assessed at baseline, between week 3 and 6 of training. Acute bone marker (Bone ALP, CTX-I) and hormone (testosterone, IGF-1, IGFBP-3, cortisol) responses were assessed at weeks 1 and 6, with blood collection done in the morning after an overnight fast. The main findings were that the acute bone formation marker (Bone ALP) showed significant changes for TR70 and BFR20 but there was no difference between weeks 1 and 6. TR70 had acute increases in testosterone, IGF-1, and IGFBP-3 (weeks 1 and 6). BFR20 had significant acute increases in testosterone (weeks 1 and 6) and in IGF-1 at week 6, while TR45 had significant acute increases in testosterone (week 1), IGF-1 (week 6), and IGFBP-3 (week 6). Strength and muscle size gains were similar for the training groups. In conclusion, low intensity BFR resistance training was effective for stimulating acute bone formation marker and hormone responses, although TR70 showed the more consistent hormone responses than the other training groups.

Exercise Therapy for People With Sarcopenic Obesity: Myokines and Adipokines as Effective Actors.

Sarcopenic obesity is defined as a multifactorial disease in aging with decreased body muscle, decreased muscle strength, decreased independence, increased fat mass, due to decreased physical activity, changes in adipokines and myokines, and decreased satellite cells. People with sarcopenic obesity cause harmful changes in myokines and adipokines. These changes are due to a decrease interleukin-10 (IL-10), interleukin-15 (IL-15), insulin-like growth factor hormone (IGF-1), irisin, leukemia inhibitory factor (LIF), fibroblast growth factor-21 (FGF-21), adiponectin, and apelin. While factors such as myostatin, leptin, interleukin-6 (IL-6), interleukin-8 (IL-8), and resistin increase. The consequences of these changes are an increase in inflammatory factors, increased degradation of muscle proteins, increased fat mass, and decreased muscle tissue, which exacerbates sarcopenia obesity. In contrast, exercise, especially strength training, reverses this process, which includes increasing muscle protein synthesis, increasing myogenesis, increasing mitochondrial biogenesis, increasing brown fat, reducing white fat, reducing inflammatory factors, and reducing muscle atrophy. Since some people with chronic diseases are not able to do high-intensity strength training, exercises with blood flow restriction (BFR) are newly recommended. Numerous studies have shown that low-intensity BFR training produces the same increase in hypertrophy and muscle strength such as high-intensity strength training. Therefore, it seems that exercise interventions with BFR can be an effective way to prevent the exacerbation of sarcopenia obesity. However, due to limited studies on adipokines and exercises with BFR in people with sarcopenic obesity, more research is needed.

Near-infrared spectroscopy during low-intensity blood flow restriction resistance exercise

Introduction: Low-intensity resistance exercises with blood flow restriction are known to be effective in promoting muscular strength and hypertrophy; however, there is a paucity of evidence on their acute hemodynamic responses. Objective: To compare the changes in muscular oxyhemoglobin (O2Hb), deoxyhemoglobin (HHb) concentrations, and O2 saturation (StO2) during low load exercise under free blood flow (FreeBF) and blood flow restriction (BFR). Methods: Fifteen healthy males were subjected to bilateral knee extension tests under FreeBF and BFR conditions, in a random order. The knee extension exercise included four sets of 15 repetitions at 20% of one-repetition maximum, with 30s interval between the sets. In the BFR condition, subjects exercised with a cuff positioned on the proximal thigh and inflated to 50% of total occlusion pressure. Changes in the O2Hb, HHb, total hemoglobin (tHb), and StO2 in vastus lateralis muscle were monitored using near-infrared spectroscopy. Results: A two-way repeated-measures ANOVA revealed significant main effects for sets for all variables (P &lt; 0.05). Moreover, the values in StO2 during sets 2, 3, and 4 in BFR conditions were significantly lower than those in freeBF. Significant differences were also seen between the exercise conditions during rest intervals for HHb (rest intervals 2, 3, and 4) and tHb (rest interval 3; P &lt; 0.05). There were no significant interactions between conditions and sets or conditions and intervals for O2Hb. Conclusion: Low-intensity resistance exercise performed with BFR significantly decreased the acute muscle StO2 and increased total muscle hemoglobin.

Effects of Blood Flow Restriction Therapy for Muscular Strength, Hypertrophy, and Endurance in Healthy and Special Populations: A Systematic Review and Meta-Analysis.

Blood flow restriction (BFR) training is an increasingly applied tool with potential benefits in muscular hypertrophy, strength, and endurance. This study investigates the effectiveness of BFR training relative to other forms of training on muscle strength, hypertrophy, and endurance. We performed systematic searches of MEDLINE, Embase, and PubMed and assessed the methodological quality of included studies using the Cochrane risk of bias tool. We included 53 randomized controlled trials with 31 included in meta-analyses. For muscular strength comparing low-intensity BFR (LI-BFR) training with high-intensity resistance training (HIRT), the pooled mean difference (MD) for 1 repetition maximum was 5.34 kg (95% CI, 2.58-8.09; P < 0.01) favoring HIRT. When comparing LI-BFR training with HIRT for torque, the MD was 6.35 N·m (95% CI, 0.5-12.3; P = 0.04) also favoring HIRT. However, comparing LI-BFR with low-intensity resistance training (LIRT) for torque, there was a MD of 9.94 N·m (95% CI, 5.43-14.45; P < 0.01) favoring BFR training. Assessing muscle hypertrophy, the MD in cross-sectional area was 0.96 cm2 (95% CI, 0.21-1.7; P = 0.01) favoring pooled BFR training compared with nonocclusive training. Assessing endurance, V̇o2 maximum demonstrated a greater mean increase of 0.37 mL/kg/min (95% CI, -0.97 to 3.17; P = 0.64) in BFR endurance training compared with endurance training alone. Blood flow restriction training produced increases in muscular strength, hypertrophy, and endurance. Comparing LI-BFR training with HIRT, HIRT was a significantly better training modality for increasing muscle hypertrophy and strength. However, LI-BFR was superior when compared with a similar low-intensity protocol. Blood flow restriction training is potentially beneficial to those unable to tolerate the high loads of HIRT; however, better understanding of its risk to benefit ratio is needed before clinical application. Level 1.

Utilizing Low-Intensity Blood Flow Restriction Training to Improve Aerobic Capacity in Physically Active and Injured Individuals: A Critically Appraised Topic

Purpose: To determine if, in physically active individuals, low-intensity Blood Flow Restriction (BFR) training is more effective than training without BFR at improving measures of aerobic capacity. Methods: A database search was conducted for articles that matched inclusion criteria (minimum level 2 evidence, physically active participants, comparison of low-intensity BFR to no BFR training, comparison of pre-post testing with aerobic fitness or performance, training protocols &gt;2 weeks, studies published after 2010) by two authors and assessed by one using the PEDro scale (a minimum of 5/10 was required) to ensure level 2 quality studies that were then analyzed. Results: Four studies met all inclusion criteria. Three of the studies found significant improvements in aerobic capacity (VO2max) using BFR compared to no BFR. While the fourth study reported significant improvements in time to exertion (TTE) training with BFR, this same study did not find significant improvements in measures of aerobic capacity with BFR training. All compared BFR to non-BFR training. It was noted that high-intensity training without BFR was superior to both low-intensity training with and without BFR with respect to improvements in aerobic capacity. Conclusions: Moderate evidence exists to support the use of low-intensity BFR training to improve measures of aerobic capacity in physically active individuals over not using BRF. Clinicians seeking to maintain aerobic capacity in their patients who are unable, for various reasons, to perform high levels of aerobic activity may find low-intensity BFR training useful as a substitution while still receiving improvements in measures of aerobic capacity.