Low-load Resistance Research Articles

Intermittent blood flow restriction with low-load resistance training for older adults with knee osteoarthritis: a randomized, controlled, non-inferiority trial protocol

BackgroundKnee osteoarthritis (KOA) is a chronic musculoskeletal disorder characterized by pain and functional impairment. Blood flow restriction (BFR) with low-load resistance training (LLRT) demonstrates a similar improvement in clinical outcomes to high-load resistance training (HLRT) in treating KOA. It has not been established whether intermittent blood flow restriction (iBFR) with LLRT can lead to clinical outcomes that are comparable to those produced by continuous blood flow restriction (cBFR) with LLRT and HLRT. The aim of the proposed study is to evaluate the efficacy of iBFR with LLRT on pain, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), muscle strength, muscle mass, physical function, perceptions of discomfort and effort, and adherence in KOA patients.MethodsThis is a three-arm, non-inferiority, randomized controlled trial utilizing blinded assessors. Two hundred thirteen participants will be randomly allocated to one of the following three groups: iBFR group—receiving 4 months of LLRT with iBFR, twice weekly (n = 71); cBFR group—receiving 4 months of LLRT with cBFR, twice weekly (n = 71); or HLRT group—receiving 4 months of HLRT without BFR, twice weekly (n = 71). The primary outcome is pain. The secondary outcomes include the WOMAC, muscle strength, muscle mass, physical function, perceptions of discomfort and effort, and adherence. Pain and WOMAC will be measured at the baseline and 4 and 12 months after randomizations. Muscle strength, muscle mass, and physical function will be measured at the baseline and 4 months after randomizations. The perceptions of discomfort and effort will be measured during the first and final sessions.DiscussionBFR with LLRT has a similar improvement in clinical outcomes as HLRT. However, cBFR may cause elevated ratings of perceived exertion and local discomfort, compromising patient tolerability and treatment adherence. If iBFR with LLRT could produce improvement in clinical outcomes analogous to those of HLRT and iBFR with LLRT, it could be considered an alternative approach for treating patients with KOA.Trial registrationChinese Clinical Trial Registry ChiCTR2300072820. Registered on June 26, 2023.

Cerebral cortex activation and functional connectivity during low-load resistance training with blood flow restriction: An fNIRS study.

Despite accumulating evidence that blood flow restriction (BFR) training promotes muscle hypertrophy and strength gain, the underlying neurophysiological mechanisms have rarely been explored. The primary goal of this study is to investigate characteristics of cerebral cortex activity during BFR training under different pressure intensities. 24 males participated in 30% 1RM squat exercise, changes in oxygenated hemoglobin concentration (HbO) in the primary motor cortex (M1), pre-motor cortex (PMC), supplementary motor area (SMA), and dorsolateral prefrontal cortex (DLPFC), were measured by fNIRS. The results showed that HbO increased from 0 mmHg (non-BFR) to 250 mmHg but dropped sharply under 350 mmHg pressure intensity. In addition, HbO and functional connectivity were higher in M1 and PMC-SMA than in DLPFC. Moreover, the significant interaction effect between pressure intensity and ROI for HbO revealed that the regulation of cerebral cortex during BFR training was more pronounced in M1 and PMC-SMA than in DLPFC. In conclusion, low-load resistance training with BFR triggers acute responses in the cerebral cortex, and moderate pressure intensity achieves optimal neural benefits in enhancing cortical activation. M1 and PMC-SMA play crucial roles during BFR training through activation and functional connectivity regulation.

Low-Load and High-Load Resistance Exercise Completed to Volitional Fatigue Induce Increases in Postexercise Metabolic Responses With More Prolonged Responses With the Low-Load Protocol.

Grisebach, D, Bornath, DPD, McCarthy, SF, Jarosz, C, and Hazell, TJ. Low-load and high-load resistance exercise completed to volitional fatigue induce increases in post-exercise metabolic responses with more prolonged responses with the low-load protocol. J Strength Cond Res 38(8): 1386-1393, 2024-Comparisons of high-load with low-load resistance training (RT) exercise have demonstrated no differences in postexercise metabolism when volume is matched. This important limitation of matching or equating volume diminishes benefits of the low-load RT protocol. Therefore, the purpose of this study was to determine the effects of acute low-load high volume and high-load low volume RT protocols completed to volitional fatigue on postexercise metabolism. Eleven recreationally active resistance-trained male subjects (24 ± 2 years; BMI: 25.3 ± 1.5 kg·m -2 ) completed 3 experimental sessions: (a) no-exercise control (CTRL); (b) RT at 30% 1 repetition maximum (1RM; 30% 1RM); and (c) RT at 90% 1RM (90% 1RM) with oxygen consumption (V̇ o2 ) measurements 2 hours postexercise. The RT sessions consisted of 3 sets of back squats, bench press, straight-leg deadlift, military press, and bent-over rows to volitional fatigue completed sequentially with 90 seconds of rest between sets and exercises. Changes were considered important if p < 0.100 with a ≥medium effect size. V̇ o2 1 hour postexercise was elevated following 30% 1RM (25%; p = 0.003, d = 1.40) and 90% 1RM (14%; p = 0.010, d = 1.15) vs. CTRL and remained elevated 2 hours postexercise following 30% 1RM (16%; p = 0.010, d = 1.15) vs. CTRL. Total O 2 consumed postexercise increased following 30% 1RM and 90% 1RM (∼17%; p < 0.044, d > 0.91) vs. CTRL. Fat oxidation was elevated 1 hour postexercise following 30% 1RM and 90% 1RM (∼155%; p < 0.001, d > 2.97) and remained elevated 2 hours postexercise following 30% 1RM compared with CTRL and 90% 1RM (∼69%; p < 0.030, d > 1.03). These data demonstrate beneficial changes to postexercise metabolism following high- and low-load RT sessions, with more prolonged effects following the low-load RT protocol completed to volitional fatigue.

A series‐fed high‐quality linear array antenna for 5G maritime communications

AbstractA compact series‐fed high‐quality linear array antenna for 5G maritime communication is proposed. Building upon the wideband high‐efficiency electromagnetic radiation structure (WHEMS), a linear integrated series‐fed method is proposed, enhancing applicability in maritime environments. A self‐decoupling structure without the parasitic elements is introduced, resulting in a 7 dB increase in isolation while achieving array spacing of less than half the wavelength. The antenna has an impedance bandwidth of 19.9% (676–825 MHz) to cover the maritime 700 MHz application band, a high gain of 13–14.2 dBi, and a smaller volume compared to classical Yagi arrays with the same gain level. Furthermore, it exhibits characteristics such as low wind load, cost‐effectiveness, and high voltage resistance. The proposed antenna will play a vital role in the construction of the current 5G maritime communication network.

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

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

Low-load resistance exercise with and without blood flow restriction: Which is more effective for increasing local muscle endurance and why?

Low-load resistance exercise with and without blood flow restriction: Which is more effective for increasing local muscle endurance and why?

Distinct adaptations of muscle endurance but not strength or hypertrophy to low-load resistance training with and without blood flow restriction.

Low-load resistance training promotes muscle strength and hypertrophic adaptations when combined with blood flow restriction (BFR). However, the effect of BFR on muscle endurance remains unclear. The aim of this study was to clarify the effects of BFR on muscle performance and adaptation, with special reference to local muscle endurance. In experiment1, eight healthy men performed unilateral elbow flexion exercise to failure at 30% of one-repetition maximum with BFR (at 40% of estimated arterial occlusion pressure) and free blood flow (FBF). During the exercise, muscle activity and tissue oxygenation were measured from the biceps brachii. In experiment 2, another eight healthy men completed 6weeks of elbow flexion training with BFR and FBF. The number of repetitions to failure at submaximal load (Rmax), the estimated time for peak torque output to decay by 50% during repetitive maximum voluntary contractions (half-time), one-repetition maximum, isometric strength and muscle thickness of elbow flexors were measured pre- and post-training. Blood flow restriction resulted in fewer repetitions and lower muscle tissue oxygenation at the end of exercise than FBF, while the muscle activity increased similarly to repetition failure. Blood flow restriction also resulted in a smaller post-training Rmax, which was strongly correlated with the total exercise volume over the 6week period. Despite the smaller exercise volume, BFR resulted in similar improvements in half-time, muscle strength and thickness compared with FBF. These results suggest that the application of BFR can attenuate muscle endurance adaptations to low-load resistance training by decreasing the number of repetitions during exercise, both acutely and chronically.

Blood Flow Restriction and Veterans With Multiple Sclerosis and Advanced Disability: Protocol for a Randomized Controlled Trial.

The purpose of this study will be to determine the efficacy of low intensity lower extremity resistance training with and without blood flow restriction (BFR) on quadriceps muscle strength and thickness in veterans with advanced multiple sclerosis (MS). This will be an assessor-blinded, 2-group (1 to 1 allocation) randomized controlled trial targeting an enrollment of 58 participants with advanced MS as defined by Patient-Determined Disease Steps scale levels 4 to 7. Both groups will complete 10weeks of twice weekly low-load resistance training (20%-30% of 1-repetition max) targeting knee and hip extension, knee flexion, and ankle plantarflexion. The intervention group will perform all training using BFR, with limb occlusion pressures between 60% and 80% of maximal limb occlusion pressure. Primary outcomes will be quadriceps muscle strength and thickness. Secondary outcomes will include knee flexion and ankle plantarflexion strength, functional mobility, physical activity, and patient-reported measures. All outcomes will be assessed at baseline before the intervention, immediately after the intervention, and at a 2-month follow-up assessment. The change between groups postintervention and after the 2-month follow-up will be reported for all outcomes. All analyses will assume a 2-sided test of hypothesis (α = .05). There is very little evidence for the efficacy of exercise interventions in people with MS who have advanced mobility disability. Resistance training with BFR may be an important approach for people with advanced MS who may not tolerate more conventional, moderate-to-high intensity resistance training. The results of this study will inform clinicians regarding exercise decisions for people with advanced MS and future investigations on the role of BFR in people with MS.

Effects of low-load resistance training with blood flow restriction on muscle fiber myofibrillar and extracellular area.

Blood flow restriction applied during low-load resistance training (LL-BFR) induces a similar increase in the cross-sectional area of muscle fibers (fCSA) compared to traditional high-load resistance training (HL-RT). However, it is unclear whether LL-BFR leads to differential changes in myofibrillar spacing in muscle fibers and/or extracellular area compared to HL-RT. Therefore, this study aimed to investigate whether the hypertrophy of type I and II fibers induced by LL-BFR or HL-RT is accompanied by differential changes in myofibrillar and non-myofibrillar areas. In addition, we examined if extracellular spacing was differentially affected between these two training protocols. Twenty recreationally active participants were assigned to LL-BFR or HL-RT groups and underwent a 6-week training program. Muscle biopsies were taken before and after the training period. The fCSA of type I and II fibers, the area occupied by myofibrillar and non-myofibrillar components, and extracellular spacing were analyzed using immunohistochemistry techniques. Despite the significant increase in type II and mean (type I + II) fCSA (p < 0.05), there were no significant changes in the proportionality of the myofibrillar and non-myofibrillar areas [∼86% and ∼14%, respectively (p > 0.05)], indicating that initial adaptations to LL-BFR are primarily characterized by conventional hypertrophy rather than disproportionate non-myofibrillar expansion. Additionally, extracellular spacing was not significantly altered between protocols. In summary, our study reveals that LL-BFR, like HL-RT, induces skeletal muscle hypertrophy with proportional changes in the areas occupied by myofibrillar, non-myofibrillar, and extracellular components.

Changes in muscular strength following nine weeks of high- or low-load resistance training.

Traditional resistance training schemes often utilize higher loads for strength gains and lower loads for muscular endurance or hypertrophy. This study aimed to investigate muscular strength adaptations after nine weeks of high- or low-load resistance training. Seventeen recreationally-trained male lifters were recruited for this study (age 20.4±2.7 years) and split into high-load (85% 1-RM; N.=8) or low-load (30% 1-RM; N.=9), completing three whole-body training sessions per week for nine weeks. Each session included three working sets of repetitions to failure. At baseline and every three weeks after, knee extension/flexion were tested using an isokinetic dynamometer. Participants completed three 5-s MVIC and isokinetic muscle actions at 60°/s and 120°/s, with the highest torque value used in analysis. Predicted 1-RM testing was at baseline and end of training program. ANCOVAs were conducted to analyze changes in strength, with significance set at P<0.05. This study demonstrated similar MVIC and peak torque values for both isokinetic speeds, although there were nonsignificant decreases largely driven by the 30% group. The high-load group showed greater increases in 1-RM following the training program. This study suggests training with lighter loads may be detrimental for long term isokinetic strength, whereas heavier loads could result in maintenance and greater increases in 1-RM despite performing repetitions to failure.

Investigating the Effects of Blood Flow Restriction Exercises on Strength and Cross Section Area of Hamstring Muscles and Tendons: A Case Report

Introduction: Hamstring injuries are one of the most common tendon injuries, especially in sports that require running and jumping. A comprehensive training program can help athletes to prevent this injury. Among suggested exercises, the Nordic eccentric training can reduce the injury rate by up to 50%; however, it is a high-load exercise that cannot be prescribed in the first stages of rehabilitation. Here, we describe a football player who used low-load resistance exercise with blood flow restriction as an alternative method to strengthen their hamstring after nine months of anterior cruciate ligament reconstruction surgery&#x0D; Case Description: A 19-year-old non-professional footballer with a body mass index of 22.18 kg/cm2 was invited to participate in this study. The variables examined included strength and cross-sectional area of the hamstring muscles (mean and maximum strength) and the crosssectional area of the hamstring tendons at their origin. The treatment program included a seated hamstring curl with a load of 30% 1 RM with blood flow restriction for four weeks (thrice a week).&#x0D; Results: The hamstring muscle strength improved by 6.54%, and the cross-sectional area of the muscles and tendons changed as follows: Semimembranosus (tendon=0.07%, muscle=2.57%), semitendinosus (tendon=0.00%, muscle=-4.04%), and biceps-femoris (tendon=5.5%, muscle=4.34%).&#x0D; Conclusion: Low load resistance training with blood flow restriction in this athlete improved the strength and cross-sectional area of the hamstring muscles as well as the cross-sectional area of the tendons. The changes observed in tendon, and muscle cross-sectional areas were more prominent for biceps-femoris. This case showed that a training program with blood flow restriction may be a good alternative for people who cannot tolerate high-load exercises in the early stages of their rehabilitation. Doing more extensive studies with more cases and a control group in the future can help our knowledge in giving the best exercise prescription to our patients.

Conventional and pulsed hybrid triboelectric nanogenerator with tunable output time and wider impedance matching range

Sliding grating-structured triboelectric nanogenerators (SG-TENGs) can multiply transferred charge, reduce open-circuit voltage, and increase short-circuit current, which have wide application prospects in self-powered systems. However, conventional SG-TENGs have an ultrahigh internal equivalent impedance, which reduces the output voltage and energy under low load resistances (<10 MΩ). The Pulsed SG-TENGs can reduce the equivalent impedance to near zero by introducing a synchronously triggered mechanical switch (STMS), but its limited output time causes the incomplete charge transfer under high load resistances (>1 GΩ). In this paper, a conventional and pulsed hybrid SG-TENG (CPH-SG-TENG) is developed through rational designing STMS with tunable width and output time. The matching relationship among grid electrode width, contactor width of STMS, sliding speed, and load resistance has been studied, which provides a feasible solution for simultaneous realization of high output energy under small load resistances and high output voltage under high load resistances. The impedance matching range is extended from zero to at least 10 GΩ. The output performance of CPH-SG-TENG under low and high load resistances are demonstrated by passive power management circuit and arc discharge, respectively. The general strategy using tunable STMS combines the advantages of conventional and pulsed TENGs, which has broad application prospects in the fields of TENGs and self-powered systems.

Blood flow restriction augments exercise-induced pressure pain thresholds over repetition and effort matched conditions

ABSTRACT We sought to determine the effects of blood flow restriction (BFR) on exercise-induced hypoalgesia, specifically using low-load (LL) resistance exercise (30% 1RM) protocols that accounted for each individual’s local muscular endurance capabilities. Forty-four participants completed four conditions: (1) 70% of maximal BFR repetitions with blood flow restriction (LL+BFR exercise); (2) 70% maximal BFR repetitions without LL+BFR (LL exercise); (3) 70% maximal free flow repetitions (LL+EFFORT exercise); (4) time-matched, non-exercise control (CON). Pressure pain threshold (PPT) was measured before and after exercise. Ischaemic pain threshold and tolerance was assessed only at post. The change in upper body PPT was greater for LL+BFR exercise compared to LL exercise [difference of 0.15 (0.35) kg/cm2], LL+EFFORT exercise [difference of 0.23 (0.45) kg/cm2], and the CON condition. The change in lower body PPT was greater for LL+BFR exercise compared to LL exercise [difference of 0.40 (0.55) kg/cm2], LL+EFFORT exercise [difference of 0.36 (0.62) kg/cm2], and the CON condition. Ischaemic pain thresholds and tolerances did not change. Submaximal exercise with BFR resulted in systemic increases in PPT but had no influence on ischaemic pain sensitivity. This effect is likely unique to BFR as we did not see changes in the effort matched free flow condition.

EFFECT OF BLOOD FLOW RESTRICTION ON THE PAINFUL KNEE AFTER KNEE ARTHROPLASTY IN PATIENTS WITHOUT MECHANICAL FAILURE: PRELIMINARY RESULTS OF A PROSPECTIVE COHORT STUDY

7–20 % of the patients with a total knee arthroplasty (TKA) are dissatisfied without an indication for revision. Therapeutic options for this patient population with mostly a lack of quadriceps strength are limited. The purpose of this study is to evaluate the effect of six weeks low load resistance training with blood flow restriction (BFR) on the clinical outcome in these unhappy TKA patients.Thirty-one unhappy TKA patients (of the scheduled fifty patients) without mechanical failure were included in this prospective study since 2022. The patients participate in a supervised resistance training combined with BFR, two times a week during nine weeks. Patients were evaluated by the Knee Osteoarthritis Outcome Score (KOOS), Knee Society Score: satisfaction (KSSs) and the Pain Catastrophizing Scale (PCS). Functionality was tested using the Six Minute Walk Test (6MWT) and the 30-Second Chair Stand Test (30CST). Follow-up took place at six weeks, three months and six months after the start.Six weeks training with BFR provided statistically significant improvements in all the KOOS subscales compared to the baseline, especially for symptoms (55.1 (±15.4) versus 48.0 (±16.5); p&lt;0.001), activities in daily living (50.3 (±21.1) versus 43.7 (±17.2); p&lt;0.00) and quality of life (24.6 (±18.5) versus 17.3 (±13.0); p&lt;0.001). The PCS reduced from 27.4 (±11.0) to 23.2 (±11.4) at six weeks (p&lt;0.01), whereas the KSSs increased from 11.8 (±6.5) to 14.9 (±7.6) (p=0.021). Both the 6MWT and the 30CST improved statistically significant from respectively 319.7 (±15.0) to 341.6m (±106.5) (p&lt;0.01) and 8.6 (±3.9) to 9.3 times (±4.5) (p&lt;0.01).Blood flow restriction appears to enhance the quality of life and functional performance of unhappy TKA patients. Based on these preliminary results, BFR seems to be a promising and valuable alternative for these TKA patients with limited therapeutic options.

EFFECTS OF TWO DIFFERENT FLYWHEEL RESISTANCE TRAINING PROTOCOLS ON EXPLOSIVE KNEE EXTENSION STRENGTH: A PILOT RANDOMIZED STUDY

The aim of our study was to evaluate differences in explosive isometric knee extension strength adaptations after a flywheel squat resistance training programs performed under low- and high-load conditions. Twenty physically active adults were randomly assigned to an individually allocated high- or low-load eight-week training intervention. Isometric knee extension rate of torque development (RTD) and rate of electromyography signal rise (RER) variables were assessed pre and post eight-week intervention. Statistically significant improvements in the RTD slope variables (100 and 200 ms time intervals after the onset of torque rise; p &lt; 0,05) were observed, regardless of the training load used. Normalized averaged vastus lateralis and rectus femoris electromyography (EMG) amplitude decreased in the intervals 80 ms before, and 75, 100 and 200 ms after the onset of activation (all p &lt; 0,05), regardless of the training group. Our results suggest that high- and low-load resistance flywheel training interventions induce similar increases in explosive knee extension strength, accompanied with a decrease in time-analog normalized EMG signal amplitude.

Comparing the efficacy of low-load resistance exercise combined with blood flow restriction versus conventional-load resistance exercise in Chinese community-dwelling older people with sarcopenic obesity: a study protocol for a randomised controlled trial

IntroductionSarcopenic obesity (SO) is characterised by decreased muscle mass, diminished muscle strength and/or reduced physical performance and a high percentage of body fat (PBF). Conventional-load resistance exercise (CRE) may be difficult for older people with SO owing to their declining physical functions. Low-load resistance exercise (LRE) combined with blood flow restriction (BFR; LRE-BFR) is a viable alternative to CRE for improving muscle mass and strength and potential exercise mode for managing SO. This study has two objectives: (1) to comprehensively evaluate the efficacy of CRE and LRE-BFR in improving body composition, muscle strength, physical performance, haematological parameters, cardiovascular disease (CVD) risk factors and quality of life and (2) to compare the efficacy of CRE and LRE-BFR and explore their potential mechanisms.Methods and analysisThis work is a 12-week assessor-blinded randomised clinical trial that will be conducted thrice a week. Sarcopenia will be defined using the Asian Working Group for Sarcopenia 2019, and obesity will be determined using the criteria developed by the World Health Organization. Community-dwelling older people aged ≥ 65 years will be screened as the participants using inclusion and exclusion criteria. A total of 33 participants will be randomised into a CRE group (n = 11), an LRE-BFR group (n = 11) and a control group that will be given only health education (n = 11). The primary outcomes will be knee extensor strength and PBF, and the secondary outcomes will be body composition, anthropometric measurements, muscle strength of upper limbs, physical performance, haematological parameters, CVD risk factors and quality of life. The outcomes will be measured at the baseline (week 0), end of the intervention (week 12) and follow up (week 24). All the collected data will be analysed following the intention-to-treat principle.Ethics and disseminationThe Ethics Research Committee has approved this study (approval No. CMEC-2022-KT-51). Changes or developments in this study will be reported at www.chictr.org.cn.Trial registrationChiCTR2300067296 (3 January 2023).

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

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

An Updated Panorama of Blood-Flow-Restriction Methods.

Exercise with blood-flow restriction (BFR) is being increasingly used by practitioners working with athletic and clinical populations alike. Most early research combined BFR with low-load resistance training andconsistently reported increased muscle size and strength without requiring the heavier loads that are traditionally used for unrestricted resistance training. However, this field has evolved with several different active and passive BFR methods emerging in recent research. This commentary aims to synthesize the evolving BFR methods for cohorts ranging from healthy athletes to clinical or load-compromised populations. In addition, real-world considerations for practitioners are highlighted, along with areas requiring further research. The BFR literature now incorporates several active and passive methods, reflecting a growing implementation of BFR in sport and allied health fields. In addition to low-load resistance training, BFR is being combined with high-load resistance exercise, aerobic and anaerobic energy systems training of varying intensities, and sport-specific activities. BFR is also being applied passively in the absence of physical activity during periods of muscle disuse or rehabilitation or prior to exercise as a preconditioning or performance-enhancement technique. These various methods have been reported to improve muscular development; cardiorespiratory fitness; functional capacities; tendon, bone, andvascular adaptations; and physical and sport-specific performance and to reduce pain sensations. However, in emerging BFR fields, many unanswered questions remain to refine best practice.

The effects of low-intensity resistance training with blood flow restriction versus traditional resistance exercise on lower extremity muscle strength and motor functionin ischemic stroke survivors: a randomized controlled trial

ABSTRACT Background Blood flow restriction (BFR) training can temporarily reduce cortical GABA concentrations and increase the size of motor volleys to deafferented muscles, which can promote motor recovery in stroke survivors. Objective To determine the effect of low-intensity resistance training with BFR (LIRT-BFR) on lower extremity muscle strength, balance, functional mobility, walking capacity, gait speed, anxiety, and depression in stroke survivors and to compare the results with high-intensity resistance training (HIRT). Method It was a two-arm, single-blinded, randomized controlled trial in which 32 ischemic stroke participants were randomly allocated to LIRT-BFR or HIRT group. The LIRT-BFR group received low load resistance training (40% of 1-Repetition Maximum (1-RM)) with BFR, whereas HIRT group received high load resistance training (80% of 1-RM). The 6-Minute Walk Test (6-MWT), five-time sit-to-stand test (5TSTST), Timed Up and Go (TUG) test, and Barthel index were the primary outcome measures. The secondary outcome measures included gait speed (m/s), stride length (cm), cadence (steps/min), and Hospital Anxiety and Depression. Results All the primary and secondary outcome measures were significantly improved in both groups (p < 0.05). The LIRT-BFR group showed a slightly greater, but non-significant, improvement as compared to the HIRT group in terms of mean change observed in 6-MWT (81 m vs 62 m), 5TSTST (−5.27 vs −4.81), gait speed (0.19 vs 0.12), stride length (18 vs 13), and cadence (8 vs 6). No adverse event was reported. Conclusion LIRT-BFR produced a significant improvement in muscle strength, balance, walking capacity, and anxiety and depression in ischemic stroke patients, and the improvement are comparable to HIRT. Clinical Trial Registration NCT05281679

Feasibility of Low-Load Resistance Training Using Blood Flow Restriction for People With Advanced Multiple Sclerosis: A Prospective Cohort Study.

The objective of this study was to determine the feasibility of low-load resistance training with blood flow restriction (BFR) for people with advanced disability due to multiple sclerosis (MS). In this prospective cohort study, 14 participants with MS (Expanded Disability Status Scale [EDSS] score = 6.0 to 7.0; mean age = 55.4 [SD = 6.2] years; 71% women) were asked to perform 3 lower extremity resistance exercises (leg press, calf press, and hip abduction) bilaterally twice weekly for 8weeks using BFR. Feasibility criteria were as follows: enrollment of 20 participants, ≥80% retention and adherence, ≥90% satisfaction, and no serious adverse events related to the intervention. Other outcomes included knee extensor, ankle plantar flexor, and hip abductor muscle strength, 30-Second Sit-to-Stand Test, Berg Balance Scale, Timed 25-Foot Walk Test, 12-Item MS Walking Scale, Modified Fatigue Impact Scale, Patient-Specific Functional Scale, and daily step count. Sixteen participants consented, and 14 completed the intervention, with 93% adherence overall. All participants were satisfied with the intervention. A minor hip muscle strain was the only intervention-related adverse event. There were muscle strength improvements on the more-involved (16%-28%) and less-involved (12%-19%) sides. There were also changes in the 30-Second Sit-to-Stand Test (1.9 repetitions; 95% CI = 1.0 to 2.8), Berg Balance Scale (5.3 points; 95% CI = 3.2 to 7.4), Timed 25-Foot Walk Test (-3.3seconds; 95% CI = -7.9 to 1.3), Modified Fatigue Impact Scale (-8.8 points; 95% CI = -16.5 to -1.1), 12-Item MS Walking Scale (-3.6 points; 95% CI = -11.5 to 4.4), Patient-Specific Functional Scale (2.9 points; 95% CI = 1.9 to 3.8), and daily step count (333 steps; 95% CI = -191 to 857). Low-load resistance training using BFR in people with MS and EDSS scores of 6.0 to 7.0 appears feasible, and subsequent investigation into its efficacy is warranted. Although efficacy data are needed, combining BFR with low-load resistance training may be a viable alternative for people who have MS and who do not tolerate conventional moderate- to high-intensity training because of more severe symptoms, such as fatigue and weakness. Low-load strength training with BFR was feasible in people who have advanced disability due to MS. Using BFR may provide an alternative for people with MS who do not tolerate higher intensity training due to more severe symptoms, such as fatigue and weakness.