Effect of blood flow restriction during low-intensity resistance training on bone markers and physical functions in postmenopausal women

Systematic review and meta-analysis of the effects of blood flow restriction training on bone health in older adults

While low-intensity blood flow restriction (LI-BFR) training has recently been shown to improve bone health, there remains limited evidence regarding its impact on older adults. This meta-analysis aimed to quantitatively identify the effects of LI-BFR training on bone mineral density (BMD) and bone biomarkers compared with conventional resistance training programs. Studies were identified through searches of four databases: PubMed, Scopus, SPORTDiscus, and Web of Science. R packages were utilized for this meta-analysis. The results indicated that compared to low-intensity (LI) training, LI-BFR significantly increased BMD (ES = 0.25, 95% Confidence Interval [CI]: [0.08, 0.41], p < 0.01), osteotropic hormones (i.e., GH, ES = 1.18, 95%CI: [0.66, 1.70]), p < 0.001; IGF-1, ES = 0.89, 95% CI: [0.44, 1.33], p < 0.001), but resulted in a smaller increase in bone resorption markers (i.e., CTX, ES = -0.77, 95%CI: [-1.16, -0.37], p < 0.001). LI-BFR training demonstrated similar effects on BMD improvement as high-intensity (HI) resistance training (ES = -0.1, 95%CI: [-0.66, 0.41], p = 0.64). Furthermore, sex and training frequency moderated the secretion of osteotropic hormones (male vs. female: IGF-1, 0.51 vs. 1.64, p < 0.01; ≤ 3 times per week vs. > 3 times per week: GH, 1.62 vs. 0.68, p < 0.01, and IGF-1, 1.13 vs. 0.39, p < 0.05). In conclusion, LI-BFR training shows promise for enhancing bone health in older adults, offering benefits comparable to HI training.

Effects of resistance training on microcirculation of bone tissue and bone turnover markers in postmenopausal women with osteopenia or osteoporosis: A systematic review

After menopause, there is an imbalance between bone formation and resorption activity, which could lead to postmenopausal osteopenia or osteoporosis. Resistance training (RT) can induce mechanical stress on bone which is necessary for bone remodeling and angiogenic-osteogenic response. This systematic review aims to assess the effects of RT on bone microcirculation and bone turnover markers (BTMs) in postmenopausal women with osteopenia or osteoporosis. We conducted a comprehensive search for related studies published up to April 2023 to identify eligible articles. Out of 316 articles identified, the full texts of 69 articles were screened. There is not any study which consider the effect of resistance exercises on bone microcirculation in PMOP women, but four articles aseess the effect of RT on BTMs and were reviewed. The quality of the articles was assessed by using the Physiotherapy Evidence Database (PEDro) scale. In one study, after 6- and 12 -months RT, bone formation and bone resorption biomarkers decreased not significantly. According to another study, bone formation and resorption biomarkers increased significantly after 3-months RT. Two other studies reported increases in biomarkers of bone formation along with decreases of biomarkers in bone resorption after 6-months of RT, but these were not significant. However, these results suggest that RT had some beneficial effects on BTMs but it is not an effective tool for modifying BTMs in women with osteoporosis or osteopenia. This may be due to the site-specific skeletal stimulation that RT provides. In addition considering the effect of RT on microcirculation of bone are important . So, there is a need for further, high-quality studies in this field.

Effects of upper extremity blood flow restriction training on muscle strength and hypertrophy: a systematic review and meta-analysis

Background

Low load resistance training with blood flow restriction (LL-BFRT) has been shown to improve muscle strength and hypertrophic function. The effect of LL-BFRT on lower extremity muscle improvement has been widely discussed. However, no studies have discussed the effect of this training method on the upper extremity muscles until now. This systematic review and meta-analysis focused on the use of LL-BFRT in the upper extremity muscles.

Methods

The relevant literature was searched in four major databases including Pubmed, Web of science, the Cochrane Library and Embase from 10 June 2024. The Cochrane Collaboration's tool and GRADE methodology were used to assess the risk of bias and quality in included studies.

Results

The meta-analysis included a total of 11 articles with 220 participants. LL-BFRT and high load resistance training (HLRT) produced similar effects in improving upper extremity muscle strength (low certainty evidence, SMD: -0.35; 95%CI: -0.73 to 0.03; p: 0.07; I2: 2%) and hypertrophy (moderate certainty evidence, SMD: -0.36; 95%CI: -0.73 to 0.01; p: 0.05; I2: 0%). Compared with low load resistance training (LLRT), LL-BFRT showed greater advantages in improving upper extremity muscle strength (low certainty evidence, SMD: 0.67; 95%CI: 0.33 to 1.01; p: 0.0001; I2: 0%) and hypertrophy (low certainty evidence, SMD: 0.37; 95%CI: 0.06 to 0.67; p: 0.02; I2: 0%).

Conclusion

In general, LL-BFRT can be used as an alternative training method for HLRT to improve upper extremity muscle strength and hypertrophy. Our study shows that the effect of LL-BFRT on upper extremity muscle is limited by age and region. It is necessary to formulate reasonable exercise programs according to the characteristics of different demographic groups.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42024555514.

Effect of Blood Flow Restriction on Gait and Mobility in Older Adults: A Systematic Review and Meta-Analysis

Older adults demonstrate gait impairments that increase their risk for falls. These age-related mobility impairments are in part due to declines in muscle mass and strength. High-intensity exercise can improve muscle strength and mobility but may not be tolerable for older adults due to musculoskeletal injury and pain. Blood flow restriction (BFR) with lower-intensity exercise offers a strategy that may be more tolerable for older adults, but whether BFR improves gait and mobility in older adults is unclear. The purpose of this systematic review and meta-analysis was to determine the effect of BFR on gait and mobility in healthy older adults. PubMed, Embase, Cochrane Library, and CINAHL were systematically searched for articles utilizing BFR in older adults. Articles were included if adults were over 60 years, did not have chronic health conditions, had undergone randomized controlled trials, and presented objectively measured gait outcomes. The search identified 1501 studies, of which 9 were included in the systematic review and 8 studies in the meta-analysis. Outcome measures included the Timed Up and Go (TUG), 6-Minute Walk Test (6MWT), 400 m walk test, Short Physical Performance Battery (SPPB), and 10 m walk test. Meta-analyses found improvements in the TUG (mean difference (MD) = -0.71; 95% CI = -1.05, -0.37; p < 0.001) and SPPB (MD = -0.94; 95% CI = -1.48, -0.39; p < 0.001) in BFR compared to no BFR. There were no differences in gait speed (MD = 0.59; 95% CI = -0.22, 1.41; p = 0.16). BFR may be effective for gait and mobility tasks over shorter distances. Clinicians may consider incorporating BFR to improve mobility and gait function in older adults.

Physical fitness and blood parameters outcomes of breast cancer survivor in a low-intensity circuit resistance exercise program

There is limited evidence regarding the effect of circuit-type low-intensity resistance exercise on physical fitness and blood parameters in breast cancer survivors (BCSs). Therefore, this study aimed to investigate the effect of low-intensity circuit resistance exercise on changes in physical fitness and blood parameters in BCSs. A total of 16 BCSs participated in a low-intensity circuit resistance exercise group (LCREG). The exercise program in the LCREG consisted of 50-60% of one repetition maximum, two to three times weekly, for 24 weeks. The control group (CG) did not receive any interventions. All participants were measured for physical fitness and blood parameters before and after the exercise intervention. The results showed that LCREG significantly improved body mass index (BMI) (p = 0.012), grip strength (p = 0.017), back strength (p = 0.042), plank (p = 0.036), balance (p = 0.030), low-density lipoproteins (LDL) (p = 0.050), total cholesterol (p = 0.017), and natural killer cell activity (NKCA) (p = 0.035) after exercise compared to before exercise. The LCREG also significantly improved BMI (p = 0.001), grip strength (p = 0.014), plank (p = 0.018), balance (p = 0.012), LDL (p = 0.024), total cholesterol (p = 0.012), and NKCA (p = 0.036) compared to the CG. These findings suggest that low-intensity circuit resistance exercise can increase physical fitness levels and improve the blood index in BCSs.

The effects of blood flow restriction training on post activation potentiation and upper limb muscle activation: a meta-analysis

OBJECTIVE

This meta-analysis aims to systematically evaluate the impact of blood flow restriction training (BFRT) on muscle activation and post-activation potentiation (PAP) in the upper limbs, to provide guidance for upper limb protocols aiming to enhance explosive strength and activation.

METHODS

PubMed, CNKI, Web of Science, and EBSCO databases were queried to identify randomized controlled trials (RCTs) investigating the effects of upper limb BFRT on muscle activation and PAP. Inclusion and exclusion criteria were applied using the Cochrane bias risk tool. Literature quality assessment and statistical analysis were conducted using Revman 5.4 and Stata 17.0 software. Sensitivity analysis and funnel plots were utilized to assess result stability and publication bias.

RESULTS

A total of 31 articles involving 484 participants were included in the analysis. Meta-analysis results showed that upper limb BFRT significantly increased muscle iEMG values [SMD = 0.89, 95%CI (0.21, 1.58), p = 0.01]. BFRT had a significant effect on upper limb explosive force [SMD = 0.73, 95%CI (0.41, 1.04), p < 0.00001]. Subgroup analysis based on literature heterogeneity (I 2 = 92%, 80%) showed that exhaustive BFRT significantly decreased upper limb iEMG [SMD = -0.67, 95%CI (-1.25, -0.09), p = 0.01], with exercise modes including maximum output power of bench press [SMD = 1.87, 95%CI (0.22, 3.53), p < 0.0001], exercise intensity of 40%-70% 1RM [SMD = 1.31, 95%CI (0.61, 2.01), p < 0.0001], and pressure intensity of ≥60% AOP [SMD = 0.83, 95%CI (0.43, 1.23), p < 0.0001] reaching maximum effects and statistical significance.

CONCLUSION

Upper limb BFRT can induce muscle activation and PAP. BFRT with 40%-70% 1RM and ≥60% AOP in the upper limbs is more likely to promote PAP.

SYSTEMATIC REVIEW REGISTRATION

http://inplasy.com, identifier INPLASY202430008.

Effect of blood flow restriction training on health promotion in middle-aged and elderly women: a systematic review and meta-analysis

Background: Physical activities play an important role in alleviating the aging problem and improving the physical fitness of middle-aged and elderly people. Blood flow restriction (BFR) training, also known as pressure training, has been widely used to improve athletes' performance and rehabilitation, which is a relatively novel exercise method for improving the physical fitness of middle-aged and elderly people. The purpose of this study is to conduct a systematic review and meta-analysis of domestic and foreign randomized controlled trial studies on BFR training for middle-aged and elderly women, further explore the impact of BFR training on health status. Methods: Meta-analysis was performed according to PRISMA standards, and charts were drawn using Review Manager 5.4 and Stata 17 software. In this study, the keywords such as "pressure training", "blood restriction training", "elderly women", "KAATSU", "blood flow restriction training" were used on CNKI, China Science and Technology Journal Database, PubMed, Embase, Web of Science, Cochrane Library, EBSCO, Scopus, and randomized controlled trials were searched in all languages. The search was performed from the establishment of database to 2 January 2024. The results of the combined effect were represented by standard mean differences. Results: Among the 681 literature retrieved, six eligible English articles were included in this meta-analysis. The overall effect test of the combined effect was performed on 10 groups of data, and the results were SMD = -0.18 (95%CI: -0.91 to 0.56; p > 0.05), the maximum dynamic force of 1RM SMD = 0.97 (95%CI: 0.35 to 1.58; p < 0.05), leg compression force SMD = -0.10 (95%CI: -0.78 to 0.57; p > 0.05), heart rate SMD = 0.33 (95%CI: -2.50 to 3.17; p > 0.05), systolic blood pressure (SBP) SMD = -1.44 (95%CI: -2.17 to -0.70; p < 0.05), diastolic blood pressure (DBP) SMD = -0.69 (95%CI: 2.54 to 1.15; p > 0.05). Conclusion: BFR training had a significant effect on the increase of the maximum dynamic force of 1RM and decrease of blood pressure in middle-aged and elderly women, but there was no significant difference found in heart rate and leg compression force. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/, identifier CRD42024491642.

Lower limb blood flow occlusion increases systemic pressor response without increasing brachial arterial blood flow redistribution in women

This study was conducted to investigate the systemic hemodynamic and vascular changes in women during and after two commonly used clinical blood flow restriction (BFR) pressures at rest. There are minimal data regarding the independent effects of BFR on hemodynamic and systemic vascular changes due to pressor response, particularly among women. Therefore, this study investigated BFR-induced alterations in pressor response and systemic flow redistribution at rest during two commonly used pressures (50% and 80% limb occlusion pressure [LOP]). Fifteen women (22.1 ± 4.2 years) completed two randomised sessions involving 8-min of bilateral, lower limb restriction at 50% or 80% LOP followed by 8-min of recovery post-deflation. Changes in vascular (arterial diameter [DIA], time-averaged mean velocity [TAMV], volume flow [VF], and area) and hemodynamic (heart rate [HR] and blood pressure) measures over time (pre-, during, post-occlusion) and by session (50% vs. 80% LOP) were tested using repeated measures analysis of variance. Repeated measures correlations (rrm) quantified common intraindividual associations between BFR-induced hemodynamic and vascular responses. HR increased from baseline during 50% LOP and remained elevated during recovery (p < 0.05). HR increased from baseline during 80% LOP, while tibial VF and TAMV decreased (p < 0.03 for all). HR and TAMV values returned to baseline during recovery, while brachial artery VF decreased (p < 0.05). Changes in HR, brachial VF, and brachial TAMV were similar between 50% and 80% LOP (rrm = 0.32-0.70, p < 0.05 for all). At 80% LOP, changes in HR were positively correlated with brachial VF (rrm = 0.38) and TAMV (rrm = 0.43) and negatively correlated with tibial VF (rrm = -0.36) and TAMV (rrm = -0.30) (p < 0.05 for all). Results suggest that BFR at 80% LOP elicits an acute systemic pressor reflex without concomitant increases in brachial arterial flow, while 50% LOP elicits a subdued response.

Idiosyncratic bone responses to blood flow restriction exercise: new insights and future directions

Applying blood flow restriction (BFR) during low-load exercise induces beneficial adaptations of the myotendinous and neuromuscular systems. Despite the low mechanical tension, BFR exercise facilitates a localized hypoxic environment and increase in metabolic stress, widely regarded as the primary stimulus for tissue adaptations. First evidence indicates that low-load BFR exercise is effective in promoting an osteogenic response in bone, although this has previously been postulated to adapt primarily during high-impact weight-bearing exercise. Besides studies investigating the acute response of bone biomarkers following BFR exercise, first long-term trials demonstrate beneficial adaptations in bone in both healthy and clinical populations. Despite the increasing number of studies, the physiological mechanisms are largely unknown. Moreover, heterogeneity in methodological approaches such as biomarkers of bone metabolism measured, participant and study characteristics, and time course of measurement renders it difficult to formulate accurate conclusions. Furthermore, incongruity in the methods of BFR application (e.g., cuff pressure) limits the comparability of datasets and thus hinders generalizability of study findings. Appropriate use of biomarkers, effective BFR application, and befitting study design have the potential to progress knowledge on the acute and chronic response of bone to BFR exercise and contribute toward the development of a novel strategy to protect or enhance bone health. Therefore, the purpose of the present synthesis review is to 1) evaluate current mechanistic evidence; 2) discuss and offer explanations for similar and contrasting data findings; and 3) create a methodological framework for future mechanistic and applied research.

Effects of blood flow restriction training on bone metabolism: a systematic review and meta-analysis

Introduction: The efficacy of low-intensity blood flow restriction (LI-BFR) training programs in bone metabolism remains unclear compared to low-intensity (LI) training and high-intensity (HI) training. The aim of this review was to quantitatively identify the effects of LI-BFR training on changes in bone formation markers (i.e., bone-specific alkaline phosphatase, BALP), bone resorption (i.e., C-terminal telopeptide of type I collagen, CTX) and bone mineral density (BMD) compared with conventional resistance training programmes. Additionally, the effectiveness of walking with and without BFR was assessed. Methods: PubMed, Scopus, SPORTDiscus, Web of Science and Google Scholar databases were searched for articles based on eligibility criteria. Review Manager Version 5.4 was used for Meta-analysis. Physiotherapy Evidence Database (PEDro) was applied to assess the methodological quality of studies. Results: 12 articles were included in the meta-analysis, with a total of 378 participants. Meta-results showed that compared with LI training, LI-BFR training induced greater increments in BALP (young adults: MD = 6.70, p < 0.001; old adults: MD = 3.94, p = 0.002), slight increments in BMD (young adults: MD = 0.05, p < 0.00001; old adults: MD = 0.01, p < 0.00001), and greater decrements in CTX (young adults: MD = -0.19, p = 0.15; old adults: MD = -0.07, p = 0.003). Compared with HI training, LI-BFR training produced smaller increments in BALP (young adults: MD = -6.87, p = 0.24; old adults: MD = -0.6, p = 0.58), similar increments in BMD (MD = -0.01, p = 0.76) and similar decrements in CTX (young adults: MD = 0, p = 0.96; old adults: MD = -0.08, p = 0.13). Although there were only two studies on walking training intervention, walking training with BFR had a better effect on bone metabolism than training without BFR. Discussion: In conclusion, LI-BFR training induces greater improvements in bone health than LI training, but is less effective than HI training. Therefore, LI-BFR training may be an effective and efficient way to improve bone health for untrained individuals, older adults, or those undergoing musculoskeletal rehabilitation. Clinical Trial Registration: [https://www.crd.york.ac.uk/prospero/], identifier [CRD42023411837].

Blood Flow Restriction in Oncological Patients: Advantages and Safety Considerations

BACKGROUND

Cancer, being a highly widespread disease on a global scale, has prompted researchers to explore innovative treatment approaches. In this regard, blood flow restriction has emerged as a promising procedure utilized in diverse clinical populations with favorable results including improvements in muscle strength, cardiovascular function, and postoperative recovery. The aim of this systematic review was to assess the efficacy of blood flow restriction in cancer survivors.

METHODS

An investigation was carried out using various databases until February 2023: PubMed, Scientific Electronic Library Online, Physiotherapy Evidence Database, Scopus, Web of Science, Cochrane Plus, SPORTDiscus, Physiotherapy and Podiatry of the Complutense University of Madrid, ScienceDirect, ProQuest, Research Library, Cumulative Index of Nursing and Allied Literature Complete Journal Storage, and the gray literature. To assess the methodological quality of the studies, the PEDro scale was utilized, and the Cochrane Collaboration tool was employed to evaluate the risk of bias.

RESULTS

Five articles found that blood flow restriction was beneficial in improving several factors, including quality of life, physical function, strength, and lean mass, and in reducing postoperative complications and the length of hospital stay.

CONCLUSION

Blood flow restriction can be a viable and effective treatment option. It is important to note that the caution with which one should interpret these results is due to the restricted quantity of articles and significant variation, and future research should concentrate on tailoring the application to individual patients, optimizing load progression, ensuring long-term follow-up, and enhancing the methodological rigor of studies, such as implementing sample blinding.

Knee Loading With Blood Flow Restriction Can Enhance Recovery After Total Knee Arthroplasty

Total knee arthroplasty (TKA) is one of the most performed operations in the world, especially in the elderly. Aging has a significant effect on joint cartilage, muscle strength, and muscle mass. Following a TKA, despite the significant reduction of symptoms and the improvement in mobility, muscle strength and muscle mass recovery remains a significant challenge. Restrictions that arise from the surgical procedure include joint loading, functional activities, and range of motion, along with limitations related to the age of the individual and their previous loading history, these are the significant restrictions, at least in the early stages of rehabilitation. Evidence indicates that blood flow restriction (BFR) training has significant potential to enhance recovery via implementation of low-load or low-intensity exercise. While respecting the indications and contraindications related to BFR application, the optimization of metabolic stress seems to offer a bridging therapy to heavy load while reducing pain and inflammation. Thus, the combination of BFR and low loads may improve muscular recovery (strength and mass), and aerobic training protocols appear to show significant enhancement of multiple cardiopulmonary parameters. Mounting evidence, direct and indirect, indicate that BFR training may have the potential to benefit the pre-operative and post-operative TKA rehabilitation phases and enhance functional recovery and physical abilities in the elderly.

The Effect of Low Intensity Resistance Training with Blood Flow Restriction on Fall Resistance in Middle-Aged and Older Adults: A Meta-Analysis

OBJECTIVE

To systematically evaluate the effect of low intensity resistance training with blood flow restriction on fall resistance in middle-aged and older adults.

METHODS

PubMed, The Cochrane Library, Web of Science, Embase, EBSCO host, CNKI Database, VIP, Wanfang Database and CBMdisc were searched, and the retrieval period was from the beginning of each database to 25 July 2022. Randomized controlled trials were collected concerning the intervention of low intensity resistance training with blood flow restriction on lower limb muscle strength, muscle mass, muscle function, balance, walking and other fall resistance indicators in middle-aged and older adults. Cochrane Risk of Bias Tool was used for methodological quality assessment of the included literature. Statistical analysis was performed using RevMan 5.4 software and Stata 15.1.

RESULTS

A total of 14 randomized controlled trials (419 participants in total) were included in the study. Meta-analysis results revealed that low intensity resistance training with blood flow restriction significantly improved lower limb muscle strength (SMD = 0.51, 95%CI: [0.28, 0.74], p < 0.0001), lower limb muscle mass (MD = 1.99, 95%CI: [0.77, 3.22], p = 0.001) and walking ability (SMD = -0.89, 95% CI. [-1.71, -0.06], p = 0.03), while there was no apparent intervention effect on lower limb muscle function (SMD = 0.25, 95%CI: [-0.23, 0.73], p = 0.31) and balance (SMD = 0.22, 95%CI: [-0.08, 0.52], p = 0.15). The results of subgroup analysis showed that the intervention effect of low intensity resistance training with blood flow restriction on lower limb muscle strength was more significant in subjects aged 55-64 years, with exercise cycles of 4-8 weeks, exercise frequency of three times per week, exercise intensity of 20-30% 1RM, and vascular flow blocking pressure ≥ 120 mmHg.

CONCLUSION

Low intensity resistance training with blood flow restriction can effectively improve lower limb muscle strength, muscle mass and walking ability in middle-aged and older adults, and can serve as an important form of fall resistance training for the older adults.

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, η_p ² ≤ 0.06). Large time effects for DJ heights and the reactive strength index were observed (p < 0.001, η_p 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; η_p 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.

Blood Flow Restriction Therapy for Use After Extremity Fracture: A Critically Appraised Topic

CLINICAL SCENARIO

Blood flow restriction (BFR) therapy has emerged as a viable treatment option to enhance clinical recovery in patients with primarily muscular injuries. However, BFR therapy has been rarely investigated in patients with osseous injuries to include extremity fracture.

FOCUSED CLINICAL QUESTION

Does BFR-enhanced therapy improve clinical outcomes in patients during the acute to subacute rehabilitation period after extremity fracture?

SUMMARY OF KEY FINDINGS

(1) In cases of 2 high-performing athletes with talus and osteochondral fracture of the knee, BFR was well tolerated and an effective rehabilitation regimen. (2) In 2 randomized controlled trials evaluating BFR use in patients after operative and nonoperative management of distal radius fractures, pain with activity and self-perceived function were improved in BFR-enhanced therapy as compared with a standard rehabilitation regimen. (3) Objective clinical outcomes including radiographic healing, extremity range of motion, and grip strength evaluated by the randomized controlled trials did not differ significantly between the BFR-enhanced and standard rehabilitation groups.

CLINICAL BOTTOM LINE

BFR-enhanced therapy may improve pain and self-perceived function of the injured extremity during the acute to subacute rehabilitation period after fracture. However, there is not yet a demonstrated benefit of BFR on hastening objective measures of clinical recovery. Large-scale clinical trials comparing BFR-enhanced rehabilitation with standard rehabilitation regimens are needed to better characterize BFR use in patients with osseous injuries.

STRENGTH OF RECOMMENDATION

Two case reports and 2 randomized controlled trials provide level IIB evidence suggesting that BFR may improve pain in the acute rehabilitative stage and improve the patient's perceived function of the injured extremity, without greater improvement in objectively measured clinical parameters as compared with a standard rehabilitation regimen.

Effectiveness of Blood Flow Restriction in Neurological Disorders: A Systematic Review

There is scientific evidence that Blood Flow Restriction (BFR) is beneficial in healthy people, the elderly and patients with musculoskeletal disorders. A systematic review was conducted to evaluate the effectiveness of BFR in patients with neurological disorders. The literature search was conducted up until July 2022 in the following databases: PubMed, Web of Science (WOS), Physiotherapy Evidence Database (PEDro), LILACS, Scopus, Cumulative Index of Nursing and Allied Literature Complete (CINAHL), the Cochrane Library and Scientific Electronic Library Online (SciELO). The PEDro scale was used to analyze the methodological quality of the studies, and the Cochrane Collaboration's tool was employed to evaluate the risk of bias. A total of seven articles were included. BFR seems to be beneficial in neurological disorders. Improvements have been found in sensorimotor function, frequency and step length symmetry, perceived exertion, heart rate and gait speed, walking endurance, fatigue, quality of life, muscles thickness, gluteus density and muscle edema. No improvements were found in lower limb strength or balance. However, results must be taken with caution due to the small number of articles and to the large heterogeneity. More clinical trials are needed. These studies should homogenize the protocols used in larger samples, as well as improve their methodological quality.

Resistance circuit training combined with hypoxia stimulates bone system of older adults: A randomized trial

PURPOSE

Aging leads to gradual irreversible decline in bone mass. As adherence to pharmacological treatment is poor, hypoxia combined with strength training has been suggested for therapeutic benefit for clinical populations. The present study investigated the effects of normobaric cyclic hypoxic exposure combined with resistance circuit training on bone of older adults.

METHODS

Healthy older adults (n = 50) were randomly assigned to a (1) control group (CON; n = 20), who were instructed to continue with their normal daily activities, (2) a group that performed resistance training in normoxia (RTN; n = 17) and (3) a group that performed resistance training in hypoxia (RTH; n = 13). During 24 weeks, RTH group performed resistance training with elastic bands under normobaric hypoxic conditions (16.1 % FiO2). A session of both exercise groups included nine exercises of several body areas with a structure of 3 sets × 12-15 repetitions per exercise, with a 1-minute rest between sets. Bone mineral density (g·cm-2) was measured using dual-energy X-ray absorptiometry. Bone turnover markers of formation (N-terminal propeptide of type I procollagen; PINP) and resorption (C-terminal telopeptide of type I collagen; bCTX) were analysed with enzyme-linked immunosorbent assay (ELISA) microplate reader.

RESULTS

Values of bCTX and bCTX/PINP significant decreased in RTN (bCTX: 47.79 %; p = 0.002; bCTX/PINP: 61.43 %; p = 0.007) and RTH (bCTX: 59.09 %; p = 0.001; bCTX/PINP: 62.61 %; p = 0.003) groups compared with CON group. Change in bone mineral density was not significantly different between groups. Based on clinically significant change, 23 % of the participants in the RTH group reached this value for femoral neck and trochanter bone mineral density (vs 0 % and 6 % of the RTN group, respectively).

CONCLUSIONS

24-Weeks of normobaric cyclic hypoxic exposure combined with resistance circuit training has potential to generate positive effects on bone in older adults.

TRIAL REGISTRATION NUMBER

NCT04281264 (date of registration: February 24, 2020).

Acute effects of the resistance exercise associated with different blood flow restriction pressures on bone remodeling biomarkers

Background

The present study analyzed the acute responses of parathyroid hormone (PTH) and bone-specific alkaline phosphatase (BSAP) to the low-intensity resistance exercise with blood flow restriction using different occlusion pressures.

Methods

Twelve women completed the three protocols of this crossover study: resistance exercise without blood flow restriction (RE), resistance exercise with blood flow restriction and occlusion pressure corresponding to 70% of systolic blood pressure (RE + BFR70), and resistance exercise with blood flow restriction and occlusion pressure corresponding 130% of systolic blood pressure (RE + BFR130). All exercises were performed in a guided squat apparatus with load corresponded to 30% of one-repetition maximum test.

Results

Relative to resting levels, PTH concentrations decreased significantly (p = .000) post-exercise in all groups and increased significantly (p = .000) 15 min post-exercise in RE + BFR70 and RE + BFR130 groups; PTH concentrations returned to resting levels after the 30-min recovery period in all groups. There was no significant difference (p >.05) between BSAP values at rest and 30 min post-exercise.

Conclusion

In conclusion, our results showed that protocols with blood flow restriction using occlusion pressures equivalent to 70% and 130% of systolic blood pressure were more effective than RE alone to induce PTH peaks, and to promote a metabolic condition favorable to bone anabolism.

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.

Molecular Regulation of Skeletal Muscle Growth and Organelle Biosynthesis: Practical Recommendations for Exercise Training

The regulation of skeletal muscle mass and organelle homeostasis is dependent on the capacity of cells to produce proteins and to recycle cytosolic portions. In this investigation, the mechanisms involved in skeletal muscle mass regulation-especially those associated with proteosynthesis and with the production of new organelles-are presented. Thus, the critical roles of mammalian/mechanistic target of rapamycin complex 1 (mTORC1) pathway and its regulators are reviewed. In addition, the importance of ribosome biogenesis, satellite cells involvement, myonuclear accretion, and some major epigenetic modifications related to protein synthesis are discussed. Furthermore, several studies conducted on the topic of exercise training have recognized the central role of both endurance and resistance exercise to reorganize sarcomeric proteins and to improve the capacity of cells to build efficient organelles. The molecular mechanisms underlying these adaptations to exercise training are presented throughout this review and practical recommendations for exercise prescription are provided. A better understanding of the aforementioned cellular pathways is essential for both healthy and sick people to avoid inefficient prescriptions and to improve muscle function with emergent strategies (e.g., hypoxic training). Finally, current limitations in the literature and further perspectives, notably on epigenetic mechanisms, are provided to encourage additional investigations on this topic.