Restricted Flow Research Articles

Research Progress on the Intervention Effects of Different Exercise Forms on Risk Factors for Obesity-Related Cardiovascular Diseases

Obesity has become a major global health issue and is an independent risk factor for several cardiovascular risks. Exercise, as a therapeutic method, is commonly used to improve cardiovascular health in obese populations. This paper reviews and analyzes the effects of five different exercise forms on risk factors for obesity-related cardiovascular diseases: Moderate-Intensity Continuous Training (MICT), High-Intensity Interval Training (HIIT), Sprint Interval Training (SIT), aerobic combined with resistance training, and Blood Flow Restriction Training (BFR). The aim is to explore the similarities and differences in health benefits among these exercise forms for individuals with obesity. The review finds that MICT is notably effective in reducing cardiovascular disease risk factors and promoting cardiovascular health in obese individuals. In contrast, high-intensity interval exercises such as HIIT and SIT show even more significant improvements in cardiovascular health. This difference may be attributed to varying biological effects caused by different intensity levels and intervals, though the specific mechanisms require further clarification. Since increased skeletal muscle can enhance basal metabolic rate and positively impact the cardiovascular system, resistance training is often recommended in combination with aerobic training for better results. Additionally, BFR can achieve similar training effects under lower exercise loads, providing a safer training option for obese individuals. Future research should focus on the mechanisms by which different exercise forms affect specific cardiovascular disease risk factors and how to optimize exercise programs based on individual differences to enhance personalization and scientific validity of interventions.

Acute Responses of Low-Load Resistance Exercise with Blood Flow Restriction

Blood flow restriction (BFR) is a popular resistance exercise technique purported to increase metabolic stress and augment training adaptations over time. However, short-term use may lead to acute neuromuscular fatigue and higher exertion ratings. Objective: The purpose of the current study was to examine acute physiological responses to low-load resistance exercise utilizing BFR compared to higher-load, non-BFR resistance exercise. Methods: Recreationally trained males (n = 6) and females (n = 7) (mean ± standard deviation, age: 20 ± 1 yrs.; height: 172 ± 8 cm; weight: 73 ± 11 kg; BMI: 24.4 ± 2.2 kg·m−2; training experience: 4 ± 2 yrs.) had limb occlusion pressure determined (50%; right leg: 118 ± 11 mmHg; left leg: 121 ± 13 mmHg) using an automated, self-inflating cuff system during baseline testing. In subsequent sessions, using a randomized, cross-over design, participants completed one of two experimental conditions: (1) Low-load + BFR and (2) High load + non-BFR. In both conditions, participants completed one set of back squats at either 30% (BFR) or 60% (non-BFR) of an estimated 1RM for a max of 30 repetitions, followed by three additional sets with the same loads and a target of 15 repetitions per set. Blood lactate and countermovement jump (CMJ) height were measured pre- and post-back squat. Ratings of perceived exertion (RPE) were assessed following each set. Results: When collapsed across all sets, participants completed significantly more total repetitions in the BFR condition compared to non-BFR (75.0 ± 0.0 vs. 68.23 ± 9.27 reps; p = 0.015; ES: 1.03), but a lower training load volume (2380 ± 728 vs. 4756 ± 1538 kg; p < 0.001; ES: 1.97). There was a significant time-by-condition interaction (p < 0.001), with a greater increase in blood lactate occurring from baseline to post-back squat in the non-BFR condition (11.61 mmol/L, 95%CI: 9.93, 13.28 mmol/L) compared to BFR (5.98 mmol/L, 95%CI: 4.30, 7.65 mmol/L). There was another significant time-by-condition interaction (p = 0.043), with a greater reduction in CMJ occurring in the non-BFR condition (−6.01, 95%CI: −9.14, −2.88 cm; p < 0.001) compared to BFR (−1.50, 95%CI: −1.50, 4.51 cm; p = 0.312). Conclusions: Utilizing a low-load BFR protocol may allow for a higher training volume, yet lower metabolic stress and reduce neuromuscular fatigue compared to lifting at a higher load without the use of BFR.

Daily blood flow restriction does not affect muscle fiber capillarization and satellite cell content during two weeks of bed rest in healthy young men.

The present study assessed whether single-leg daily blood flow restriction (BFR) treatment attenuates the decline in muscle fiber size, capillarization, and satellite cell (SC) content during 2 weeks of bed rest in healthy, young men. Twelve healthy, young men (age: 24±3 y; BMI: 23.7±3.1 kg/m2) were subjected to 2 weeks of bed rest, during which one leg was exposed to three times daily 5 min of BFR, whereas the contralateral leg received sham treatment (CON). Muscle biopsies were obtained from the M. vastus lateralis from both the BFR and CON leg before and immediately after the 2 weeks of bed rest. Type I and II muscle fiber size, myonuclear content, capillarization, and SC content were assessed by immunohistochemistry. No significant decline in either type I or type II muscle fiber size were observed following bedrest, with no differences between the CON and BFR leg (P>0.05). Type I muscle fiber capillary density increased in response to bed rest in both legs (P<0.05), while other muscle fiber capillarization measures remained unaltered. SC content decreased in both type I (from 7.4±3.2 to 5.9±2.7 per 100 fibers) and type II (from 7.2±3.4 to 6.5±3.2 per 100 fibers) muscle fibers (main effect of time P=0.018), with no significant differences between the BFR and CON leg (P>0.05). In conclusion, two weeks of bed rest has no effect on muscle capillarization, decrease the SC content and daily BFR treatment does not affect skeletal muscle fiber size and SC content in healthy, young men.

Cavitation characteristics in rectangular flow restriction microchannel seals

The shaft seal of the primary pump relies on microchannel flow to prevent coolant leakage, but cavitation increases resistance, reduces efficiency, and damages equipment, affecting safety. Therefore, studying microchannel cavitation is crucial for optimizing seal performance and equipment reliability. This study explores the cavitation flow characteristics within a 0.1 mm rectangular flow restriction microchannel seal through experimental methods and numerical simulations. First, using a microfluidic experimental platform and visualization techniques, we directly observed the cavitation phenomena in the microchannel and quantified the evolution of cavitation bubbles under different conditions. Second, by establishing a numerical model of the microchannel, we analyzed the formation mechanisms of cavitation and its impact on flow characteristics under various conditions. The results show that lower cavitation numbers significantly increase the length of cavitation jets and the distribution range of cavitation bubbles, intensifying the cavitation phenomena within the microchannel. Additionally, microchannels with closely spaced double flow restriction structures are more effective at inhibiting cavitation than channels with a single flow restriction structure. These findings offer valuable insights into the mechanisms of microchannel cavitation and provide scientific guidance for the design and optimization of shaft seals.

Efficacy of Blood Flow Restriction Exercise for Improving Lower Limb Muscle Strength and Function in Chronic Spinal Cord Injury: A Randomized Controlled Trial.

The objective of the present study was to evaluate the efficacy of low-load (LL) blood flow restriction exercise (BFRE) for improving lower limb muscle strength, muscle thickness and physical function in individuals with spinal cord injury (SCI). In a randomized sham-controlled trial, 21 participants (age ≥ 18 years, SCI duration ≥ 1 year, knee extensor strength grade 2-4, ASIA A-D) were randomized to either 45-min LL-BFRE (n = 11) or sham BFRE (n = 10) twice/week for 8 weeks. The exercise protocol consisted of four sets (30 × 15 × 15 × 15 repetitions) of unilateral seated leg extensions and leg curls at 30%-40% of 1RM performed with pneumatic cuffs applied proximally on the trained limb and inflated to 40% of total arterial occlusion pressure (BFRE) or non-inflated (sham exercise). Maximal voluntary isometric quadriceps and hamstring muscle strength, quadriceps muscle thickness, thigh circumference, and physical function were assessed at baseline, after 4 and 8 weeks of training and at 4-week follow-up. No significant between-group differences were found between BFRE and sham exercise in quadriceps or hamstring muscle strength, 10-m walking test, timed up & go, 6-min walking test or the spinal cord independence measure. In contrast, a significant between-group difference favoring BFRE was present for muscle thickness and thigh circumference from baseline to 4-week follow-up (0.76 cm (95% CI: 0.32; 1.20, p = 0.002) and 2.42 cm (0.05; 4.79, p = 0.05), respectively). In conclusion, there was no significant difference in the effect of LL-BFRE and sham exercise on muscle strength and physical function in individuals with SCI. However, significant increases in muscle thickness and thigh circumference were observed in favor of BFRE. Trial Registration: ClinicalTrials.gov identifier: NCT03690700.

ДИНАМИКА ВАРИАБЕЛЬНОСТИ СЕРДЕЧНОГО РИТМА ПОСЛЕ СИЛОВЫХ ТРЕНИРОВОК С ОГРАНИЧЕНИЕМ КРОВОТОКА У ЛИЦ С МЕТАБОЛИЧЕСКИМ СИНДРОМОМ

We know that autonomic disfunction is due to metabolic pathologies. The same time, physical activity has beneficial effects on metabolic health and heart rate variability (HRV). But there is no consensus about the effect of trainings with weights on HRV in the scientific literature. Purpose: To asses the impact of low-intensity power trainings with blood flow restrictions on HRV of men with metabolic syndrome (MS). Materials and methods: Influence of different weight training modes on 60 men with MS was analyzed. The participants were divided into three groups: low-load resistance training with blood flow restriction (LLBFR; n = 20), high-intensity resistance training without blood flow restriction (HI; n = 20), low-load resistance training without blood flow restriction (LL; n = 20). Trainings were conducted twice a week for 12 weeks. Time and frequency indicators were assessed before and after the investigation. Results: After the investigation, there were an increase in SDNN for the LLBFR group (p = 0.000; Cohen’s d = 0.69), for the HI group (p = 0.000; Cohen’s d = 0.83), for the LL group (p = 0.016; Cohen’s d = 0.22), an increase in RMSSD for the LLBFR group (p = 0.000; Cohen’s d = 0.67), for the HI group (p = 0.000; Cohen’s d = 0.87), for the LL group (p = 0.027; Cohen’s d = 0.26), as well as an increase in pNN50 for the LLBFR group (p = 0.000; Cohen’s d = 0.58), for the HI group (p = 0.000; Cohen’s d = 0.53), for the LL group (p = 0.079; Cohen’s d = 0.14). Statistically significant changes (p ˂ 0.05) were also observed for the frequency parameters of HRV for the LLBFR and HI groups. Conclusions: Resistance training, including in combination with blood flow restriction, has a positive effect on HRV in men with MS.

The Effect of Combined Exercises with and Without Blood Flow Restriction and Vitamin D Supplementation on Serum Levels of Alkaline Phosphatase in Elderly Women: A Randomized Clinical Trial Study

The Effect of Combined Exercises with and Without Blood Flow Restriction and Vitamin D Supplementation on Serum Levels of Alkaline Phosphatase in Elderly Women: A Randomized Clinical Trial Study

Can blood flow restriction therapy improve quality of life and function in dissatisfied knee arthroplasty patients?

Approximately 10% to 20% of knee arthroplasty patients are not satisfied with the result, while a clear indication for revision surgery might not be present. Therapeutic options for these patients, who often lack adequate quadriceps strength, are limited. Therefore, the primary aim of this study was to evaluate the clinical effect of a novel rehabilitation protocol that combines low-load resistance training (LL-RT) with blood flow restriction (BFR). Between May 2022 and March 2024, we enrolled 45 dissatisfied knee arthroplasty patients who lacked any clear indication for revision to this prospective cohort study. All patients were at least six months post-surgery and had undergone conventional physiotherapy previously. The patients participated in a supervised LL-RT combined with BFR in 18 sessions. Primary assessments included the following patient-reported outcome measures (PROMs): Knee injury and Osteoarthritis Outcome Score (KOOS); Knee Society Score: satisfaction (KSSs); the EuroQol five-dimension five-level questionnaire (EQ-5D-5L); and the pain catastrophizing scale (PCS). Functionality was assessed using the six-minute walk Test (6MWT) and the 30-second chair stand test (30CST). Follow-up timepoints were at baseline, six weeks, three months, and six months after the start. Six weeks of BFR with LL-RT improved all the PROMs except the sports subscale of the KOOS compared to baseline. Highest improvements after six weeks were found for quality of life (QoL) (mean 28.2 (SD 17.2) vs 19 (SD 14.7); p = 0.002), activities of daily living (mean 54.7 (SD 18.7) vs 42.9 (SD 17.3); p < 0.001), and KSSs (mean 17.1 (SD 8.8) vs 12.8 (SD 6.7); p < 0.001). PROMs improvements continued to be present at three-month and six-month follow-up compared to baseline. However, no significant differences were observed in the paired comparisons of the six-week, three-month, and six-month follow-up. The same trends are observed for the 6MWT and 30CST. The reported regime demonstrates improved QoL and function of dissatisfied knee arthroplasty patients. In light of this, the pathway described may provide a valuable and safe treatment option for dissatisfied knee arthroplasty patients for whom therapeutic options are limited.

Decoupling of redox processes from soil saturation in Arctic tundra

Permafrost thaw in warming Arctic landscapes alters hydrology and saturation-driven biogeochemical processes. Models assume that aerobic respiration occurs in drained soils while saturated soils support methanogenesis; however, saturated soils maintain redox gradients that host a range of anaerobic metabolisms. We evaluated how redox potential and redox-active solutes vary with soil moisture in the active layer of permafrost-affected acidic and non-acidic tundra hillslopes. Oxidizing conditions persisted in highly permeable organic horizons of both unsaturated tussock tundra and saturated wet sedge meadows. Redox potential decreased with depth in all soils as increasing soil bulk density restricted groundwater flow and oxygen diffusion. High concentrations of dissolved iron, phosphate, and organic carbon coincided with redox boundaries below the soil surface in acidic tundra, indicating active iron redox cycling and potential release of adsorbed phosphate during iron (oxyhydr)oxide dissolution. In non-acidic tundra, weatherable minerals affected nutrient dynamics more than redox-driven iron cycling, especially in low-lying, saturated areas where thaw reached mineral soils. The role of thaw depth and the ability of saturated soils to maintain oxidizing conditions in organic surface layers highlight the importance of soil physical properties and hydrology in predicting biogeochemical processes and greenhouse gas emissions.

Boys vs men differences in muscular fatigue, muscle and cerebral oxygenation during maximal effort isometric contractions: the effect of muscle blood flow restriction.

To examine whether the children's superiority, over adults, to resist fatigue during repeated maximal-efforts depends on their often-cited oxidative advantage, attributed to greater muscle blood flow and O2-delivery. We also investigated the mechanisms underlying child-adult differences in muscle-oxygenation (due to O2-supply or O2-utilization) and examined if there are age-differences in cerebral-oxygenation response (a brain-activation index). Eleven men (23.3 ± 1.8yrs) and eleven boys (11.6 ± 1.1yrs) performed 15 maximal-effort handgrips (3-s contraction/3-s rest) under two conditions: free-flow circulation (FF) and arterial-occlusion (OCC). Force, muscle-oxygenation (TSImuscle) and cerebral-oxygenation (oxyhemoglobin-O2Hbcerebral; total hemoglobin-tHbcerebral; deoxyhemoglobin-HHbcerebral) were assessed. In boys, force declined less (-26.3 ± 2.6 vs. -34.4 ± 2.4%) and at slower rate (-1.56 ± 0.16 vs. -2.24 ± 0.17%·rep-1) vs. men in FF (p < 0.01-0.05; d = 0.60-1.24). However, in OCC there were no age-differences in the magnitude (-38.3 ± 3.0 vs. -37.8 ± 3.0%) and rate (-2.44 ± 0.26 vs. -2.54 ± 0.26%·rep-1) of force decline. Boys compared to men, exhibited less TSImuscle decline in both protocols, and lower muscle VO2 (p < 0.05). Boys, also, presented a smaller O2Hbcerebral and tHbcerebral rise than men in FF; exercising with OCC increased the O2Hbcerebral and tHbcerebral response in boys. Using MVIC as a covariate in FF condition, abolished boys-men differences in force and TSImuscle decline and O2Hbcerebral rise. During repeated maximal-efforts: (i) blood flow is a significant contributor to children's superiority over adults to resist fatigue; (ii) age-difference in muscle hypoxia/deoxygenation is rather attributed to men's greater metabolic demand than to lower muscle-perfusion; and (iii) cerebral oxygenation/blood volume increase more in men than boys under free circulation, implying greater brain activation.

Derivation of fractured rock hybrid analytical equation for estimation of groundwater inflow into mine pit using major fault trigonometry

ABSTRACT In hydrogeology, equations describing exchange flux in sedimentary systems mainly focus on the geometry of the streambed–aquifer system and parameters. However, groundwater flow in fractured crystalline basement and volcanic rocks, which are mainly characterized by restricted flow, receives little attention in groundwater flow equations, possibly due to a lack of appropriate data. This study develops an analytical equation to estimate groundwater inflow into mine pits in volcanic rock, addressing a significant knowledge gap in the literature. The equation was validated through a case study evaluation at the Nsuta Mine, where it accurately estimated groundwater inflow into the pit. Results indicate that estimated inflow at the current pit floor level (−60 MSL) is 38 710 m3/day, which is close to the actual dewatering rate of 39 794 m3/day (error percentage of 2.8%). The study also projects groundwater inflow at a deeper pit level (−200 MSL) to be 82 400 m3/day with a corresponding flux of 0.331 m/day.

Effectiveness of heat source/sink and Lorentz force constraints in a non-Newtonian peristaltic arterial blood hybrid nanofluid past an overlapping stenotic artery

Recently a considerable amount of attention has been directed towards the technological advancements in the study of arterial stenosis. The deposition of adipose tissues and saturated fatty acids and the abnormal growth of flesh, narrows the arteries, leading to restricted blood flow. This causes cardiovascular diseases like atherosclerosis, atherogenesis, atheroma, etc. Considering this the present research paper develops a Casson fluid model to investigate magnetohydrodynamic peristaltic transport of the passage of blood through slightly stenosed arteries due to the influence of copper (Cu) and alumina (Al2O3) nanoparticles. The problem is formulated using appropriate mathematical models employing non-dimensional parameters and stenosis approximations. The study has its applications in the field of medicine. The outcome of this work is that it helps to handle many heart conditions. The findings of this investigation may have benefits in various academic fields, including pharmaceuticals and other industries. In addition, they are remarkably beneficial in the treatment of numerous cardiovascular diseases.

The effect of low-intensity resistance training with practical blood flow restriction (pBFR) and transcranial direct current stimulation (tDCS) on thickness, strength and electrical activity of biceps brachii muscle in healthy men

The effect of low-intensity resistance training with practical blood flow restriction (pBFR) and transcranial direct current stimulation (tDCS) on thickness, strength and electrical activity of biceps brachii muscle in healthy men

Investigating the Influence of Limb Blood Flow on Contraction-Induced Muscle Growth and the Impact of that Growth on Changes in Maximal Strength.

Changes in skeletal muscle size may be affected by resting blood flow (e.g., nutrient delivery) and this change in size is a hypothesized mechanism for changes in strength. To determine: 1) whether the relationship between isometric training and muscle growth depends on baseline blood flow or is mediated by a change in blood flow and 2) whether muscle growth mediates changes in maximal isometric strength. 179 participants were randomized into: low-intensity isometric handgrip exercise (LI), low-intensity isometric handgrip exercise with blood flow restriction (LI-BFR), maximal handgrip exercise (MAX), and a non-exercise control (CONTROL). Muscle thickness, strength, and resting limb blood flow were measured before and after the six-week intervention. Baseline blood flow did not moderate training effects on muscle thickness changes (MTHchg) (p = 0.666), and moderated mediation tests were non-significant. Although the LI-BFR group showed a significant effect on MTHchg (p = 0.018), MTHchg was not significantly related to handgrip strength change (HGchg) (p = 0.281), suggesting no mediation of the training-to-strength effect by MTHchg. Both the LI-BFR (p = 0.004) and MAX (p < 0.001) groups exhibited positive direct effects on HGchg compared to CONTROL. Furthermore, there were no differences between training groups and CONTROL on blood flow change (BFchg), BFchg and MTHchg were not significantly related, and neither BFchg nor MTHchg predicted HGchg, providing no evidence for mediated pathways. Muscle growth may not have occurred to an extent that would require vascular adaptation. Training maximally induced the greatest strength adaptations but was seemingly not driven by muscle growth.

Heterogeneous long-term and seasonal brine evolution, and Artemia fecal pellet controls on Urmia Lake (NW Iran) salt-crust formation and mineralogy

ABSTRACT Urmia Lake resides as a substantial hypersaline lake characterized by notable fluctuations in water salinity, brine composition, and water level over long-term, annual, and seasonal intervals. Extremely rapid water elevation fall (&amp;gt; 7 m) in the last three decades has caused the formation of a salt crust on the lake floor. A manmade stone causeway divided the lake into two relatively deeper northern parts with minimal water inputs and a shallower southern part with maximal river inflows. Restricted water flow through the narrow water passage of the causeway leads to complex salinity processes, brine evolution, and salt-crust formation in Urmia Lake. This research analyzes the ionic composition of lake-sediment and salt-crust pore water, the mineralogy of salt crusts, and the ionic composition of both surface and deep lake waters during both the wet and dry seasons of 2019. The findings indicate that the northern and southern parts of the lake undergo stratification during wet seasons due to significant freshwater input, whereas they become homogenized during dry seasons through progressive evaporative concentration and water mixing. The spatial and temporal variations in the lake brine type (primary Na-Mg-Cl) and ionic composition contribute to the formation of a halite salt crust (NaCl &amp;gt; 97%) with heterogeneous mineralogy and thickness. In Urmia Lake, the variable thickness and mineralogy of the exposed marginal salt crust suggest rapid salt-crust reorganization by annual and seasonal deposition and dissolution processes. Conversely, the submerged central salt crust, with continuous thickening and constant mineralogy, remains unaffected by seasonal variations in brine type and dissolution processes. It is noteworthy to mention that Artemia (a brine shrimp) controls the mineralogy of the lake salt crust through the deposition of calcium and carbonate ions in the form of biochemical fecal pellets.

Effect of blood flow restriction training on insulin resistance in men with metabolic syndrome: a randomized controlled trial

Introduction. Metabolic syndrome is defined as a pathological condition characterized by abdominal obesity, hypertension, dyslipidemia, and impaired glucose tolerance. Insulin resistance is hypothesized to underlie metabolic syndrome. Modern studies, including Mendelian randomization, have demonstrated that muscle strength and muscle mass may play an important role in the mechanisms of insulin resistance. Aim. To establish the relationship between relative upper limb muscle strength and triglyceride/glucose index, and to evaluate the effects of different resistance exercise regimens on alternative measures of insulin resistance in men with metabolic syndrome. Materials and methods. At the first stage of the study, 216 men aged from 25 to 50 years were examined. The relative muscle strength of the upper limbs in the bench press exercise and the triglyceride/glucose index were assessed. At the second stage, a randomized controlled trial was conducted, for which 60 men who met the criteria for metabolic syndrome. Men with metabolic syndrome were divided into three groups: low-intensity strength training with blood flow restriction (n = 20), high-intensity strength training (n = 20), low-intensity strength training without blood flow restriction (n = 20). Training was carried out 2 times a week for 12 weeks. Before and after the study, the triglycerides/glucose index, the ratio of triglycerides to high-density lipoproteins, and the combination of the triglycerides/glucose index with body mass index were assessed. Results and discussion. It was found that the relative muscle strength of the upper limbs was inversely proportional to the triglycerides/glucose index (r = –0.52; p 0.05) in the examined men. After 12 weeks of resistance training, statistically significant reductions in triglyceride/glucose index, triglyceride/high-density lipoprotein ratio, and triglyceride/glucose index/body mass index combination were found for the low-intensity resistance training with blood flow restriction and high-intensity resistance training groups (both, p 0,01). Changes in body composition, an increase in the proportion of muscle fibers I and IIa and a decrease in the proportion of muscle fibers IIx, an increase in the activity of glucose transporters, and a decrease in systemic inflammation are the main potential mechanisms for the beneficial effects of resistance training, including in combination with blood flow restriction, on insulin resistance in men with metabolic syndrome. Conclusion. There is an inverse relationship between muscle strength and triglycerides/glucose index; resistance training is an effective and safe tool for reducing alternative indicators of insulin resistance and can be included in comprehensive correction programs for men with metabolic syndrome.

Combining practical blood flow restriction with elastic band resistance training neither affects strength nor muscle thickness in young males

The purpose of this study was to determine the effect of eight weeks of elastic band resistance training (EBRT) program associated with practical blood flow restriction (BFR) on muscle strength and hypertrophy. Fourteen physically active male participated in an eight-week upper limbs EBRT program, with one limb under BFR and the other with free blood flow (EBRT+BFR). Bilateral and unilateral elbow flexion exercises were performed three times a week, with three sets of 15 repetitions in each upper limb. Blood flow restriction was produced by an extensive band, implementing the pressure stipulated at 25% of the resting upper arm circumference. Significant main effect for time was found in elbow flexors muscle thickness measured with ultrasound to both training conditions, but no significant interactions in the time x group were identified. Relative strength gains measure with a dynamometer were -0.5 ± 10.2 % and 0.5 ± 12.1 % in the arms trained with EBRT and EBRT+BFR, respectively. The relative gains in elbow flexor muscle thickness were 1.8 ± 6.2 % with EBRT training and 5.5 ± 6.7 % in EBRT+BFR (both p &gt; .05). In conclusion, applying BFR to an EBRT was not superior at increasing upper limb muscular strength or hypertrophy in young adults compared to EBRT alone.

Effect of blood flow restriction training on the explosive power of lower limbs in taekwondo athletes during kicking

Objective: This paper aims to explore the effectiveness of blood flow restriction training (BFRT) on the lower extremity explosive power of Taekwondo athletes when they kick. Methods: Twenty Taekwondo athletes were randomly divided into BFRT and resistance training (RT) groups. The two groups underwent BFRT and RT for eight weeks, respectively. Indicators such as thigh and calf circumferences and countermovement jump (CMJ) performance were tested and compared. Results: In the pre-test, p &gt; 0.05 was found between the two groups. In the post-test, the left/right thigh circumferences of the BFRT group were 54.56 ± 3.21 cm and 54.37 ± 3.37 cm, respectively, and p &lt; 0.05 compared with the pre-test results and the RT group; however, no remarkable difference were observed between the RT group and pre-test results. The CMJ and static squat jump (SJ) scores in the BFRT group were 42.33 ± 7.84 m and 39.36 ± 7.52 m, respectively, and p &lt; 0.05 compared with the pre-test and the RT group; however, there was no remarkable difference between the RT group and the pre-test results. In the BFRT group, the performance of 10 s in-situ double chop kick was 27.64 ± 1.51 times, and the performance of 10 s high turning kick was 19.87 ± 1.65 times (p &lt; 0.05 compared with the pre-test results and the RT group); p &lt; 0.05 when comparing the post-test results with the pre-test results in the RT group, but the increasing amplitude was lower than that in the BFRT group. The performance of the 10 s in-situ left/right middle turning kick was 16.12 ± 1.37 times and 18.09 ± 1.98 times in the BFRT group, and p &lt; 0.05 compared with the pre-test results and the RT group; however, no remarkable difference were found between the RT group and the pre-test results. Conclusion: BFRT can effectively improve the lower extremity explosive power of taekwondo athletes during kicking, and the effect is superior to traditional RT.

Effectiveness of low-load resistance training with blood flow restriction vs. conventional high-intensity resistance training in older people diagnosed with sarcopenia: a randomized controlled trial

Low-load resistance training with blood flow restriction (LRT-BFR) has shown potential to improve muscle strength and mass in different populations; however, there remains limited evidence in sarcopenic people diagnosed with sarcopenia criteria. This study systematically compared the effectiveness of LRT-BFR and conventional high-intensity resistance training (CRT) on clinical muscle outcomes (muscle mass, strength and performance), cardiovascular disease (CVD) risk factors and sarcopenia-related biomarkers of older people with sarcopenia. Twenty-one older individuals (aged 65 years and older) diagnosed with sarcopenia were randomly assigned to the LRT-BFR (20%–30% one-repetition maximum (1RM), n = 10) or CRT (60%–70% 1RM, n = 11) group. Both groups underwent a supervised exercise program three times a week for 12 weeks. The primary outcome was knee extensor strength (KES), and the secondary outcomes included body composition (body mass, body mass index and body fat percentage), muscle mass [appendicular skeletal muscle mass index (ASMI)], handgrip strength, physical performance [short physical performance battery (SPPB) and 6-m walk], CVD risk factors [hemodynamic parameters (systolic and diastolic blood pressure and heart rate (SBP, DBP and HR)) and lipid parameters (total cholesterol, triglyceride (TG), high-density lipoprotein (HDL) and low-density lipoprotein)], sarcopenia-related blood biomarkers [inflammatory biomarkers, hormones (growth hormone (GH) and insulin-like growth factor 1) and growth factors (myostatin and follistatin)] and quality of life [Short Form 36 Health Survey (SF-36)]. Both interventions remarkably improved the body composition, KES, 6-m walk, SBP, HDL, TG, GH, FST and SF-36 scores. CRT significantly improved the ASMI (p < 0.05) and SPPB (p < 0.05). A significant improvement in HR was observed only after LRT-BFR. No significant between-group differences were found before and after the interventions. This study suggested that LRT-BFR and CRT are beneficial to the clinical muscle outcomes, CVD risk factors and certain sarcopenia-related biomarkers of older people with sarcopenia. By comparison, CRT seems more effective in improving muscle mass, while LRT-BFR may be more beneficial for improving cardiovascular health in this population. Therefore, LRT-BFR is a potential alternative to CRT for aging sarcopenia.

Stiffness of elastic cuffs affects physiological and perceptual responses but not motor performance fatigue during low external load resistance exercise with practical blood flow restriction

ABSTRACT Practical blood flow restriction (pBFR), using non-pneumatic elastic cuffs, is a feasible and cost-effective alternative to pneumatic systems. There is evidence that cuff stiffness influences haemodynamic and perceptual responses in the upper body during rest. However, the impact of cuff stiffness during exercise is still unknown. Therefore, this study investigated the influence of cuff stiffness on physiological, perceptual, and performance changes during exercise. In a randomized and counterbalanced order, ten recreationally active males performed four sets of unilateral elbow flexions at 20% of individuals’ one-repetition-maximum with two elastic cuffs of different stiffness (low stiffness cuff [LS] and high stiffness cuff [HS]) each applied with two different overlaps (10% and 20% overlap in relation to the limb circumference) as well as a control condition without pBFR. Before and after exercise, maximal voluntary isometric contraction torque was measured to assess motor performance fatigue. During exercise, muscle oxygen saturation of the biceps brachii as well as effort and exercise-induced muscle pain perception were recorded. Statistical analysis revealed that motor performance fatigue was not different between conditions (BF10 = 0.289). The decline in muscle oxygen saturation (BF10 = 8.508 and BF10 = 1039.543) as well as effort (BF10 = 2646.104 and BF10 = 2.773∙106) and exercise-induced muscle pain perception (BF10 = 14087.983 and BF10 = 7.306∙109) were higher when using the stiffer cuff at 10% and 20% overlap, respectively. Conclusively, physiological and perceptual responses but not motor performance fatigue were affected by cuff stiffness when equal relative overlaps were applied.