Effectiveness of blood flow restricted exercise compared with standard exercise in patients with recurrent low back pain: study protocol for a randomized controlled trial

Enhanced Pain Relief and Muscle Growth in Individuals with Low Back Instability: The Impact of Blood Flow Restriction Exercise during Sit to Stand Movements

BACKGROUND Blood flow restriction exercise (BFRE) improves muscle strength at a relatively low intensity by temporarily restricting blood flow. This study compared pain and quadriceps muscle mass (QMM) in 40 patients with lower back pain (LBP) undertaking sit-to-stand (STS) exercise with and without blood flow restriction. MATERIAL AND METHODS Forty adults were divided into 2 groups, and the experimental group (n=20) performed an STS exercise with BFRE, and the control group (n=20) performed an STS exercise without BFRE. Blood pressure, including systolic blood pressure (SBP) and diastolic blood pressure (DBP), was measured using a portable blood pressure monitor. Saturation of percutaneous oxygen (SpO2) was measured using oxygen saturation. Pain was measured using the visual analog scale (VAS) and the Oswestry disability index (ODI). QMM was assessed using ultrasonography. RESULTS Data were analyzed using paired and independent t tests. SBP (P=.000), DBP (P=.004), and SpO2 (P=.001) were significantly different in the experimental group, both before and during the intervention. The VAS scores showed a statistically significant difference in the post-test (P=.003) and rate of change (P=.009) between the groups. The ODI scores showed statistically significant differences in the post-test (P=.000) and rate of change (P=.001) comparison between the groups. The rate of change in QMM, including the rectus femoris (P=.000), vastus intermedius (P=.004), vastus medialis (P=.001), and vastus lateralis (P=.014), increased significantly in the experimental group compared to that in the control group. CONCLUSIONS This study demonstrates that the additive effect of BFRE on pain relief and QMM increase, thus contributing to existing knowledge about therapeutic exercise for the effective management of LBP.

Equine blood flow restriction training: Safety validation

BACKGROUND

Blood flow restriction (BFR) has become a key rehabilitative tool for human orthopaedic conditions. With modernised technology and evolution of clinical application, patient-specific delivery of occlusion percentages is now considered the standard of care in human patients due to improved therapeutic outcomes and minimised safety risks. Safety validation and limb occlusion pressure (LOP) data for horses, however, are lacking.

OBJECTIVE

(1) To determine if BFR exposure resulted in forelimb biomechanical gait dysfunction as safety validation and (2) to investigate inter-horse and inter-limb LOP differences.

STUDY DESIGN

Controlled in vivo experiment.

METHODS

Daily unilateral forelimb BFR was performed in four horses over 56 days. Clinical examinations and objective gait analyses were performed on Days 0, 28 and 56. Daily LOP values were determined by Doppler evaluation to deliver 80% vascular occlusion at a walk. A linear mixed model evaluated for differences in lameness, kinetic and kinematic gait parameters.

RESULTS

There were no significant differences in forelimb lameness (range of Grades 0-2 across all forelimbs), kinematic or kinetic gait parameters over time or between BFR-exposed and control (contralateral) limbs (p > 0.05). Clinically apparent complications related to BFR such as thrombosis or dermatitis were not appreciated. Significant differences in mean LOP values between various horses (p < 0.001) and measured left (204.48 mmHg) and right (173.78 mmHg) forelimbs (p < 0.001) were observed. Mean LOP and standard deviation across all readings was 189.1 ± 22.2 mmHg.

MAIN LIMITATIONS

Optimal BFR occlusion percentages and protocols with documented clinical efficacy are unknown. Small study population.

CONCLUSIONS

Exposure to BFR did not result in forelimb biomechanical dysfunction in four horses. Applied pressures of 75-151 mmHg would likely simulate a range of 50%-80% vascular occlusion in horses, but inherent physiological variation between horses and forelimbs warrants incorporation of individual pressures.

Effects of left thigh blood flow restriction exercise on muscle strength and golf performance in amateur golfers

This study aimed to investigate the effect of lower-extremity strengthening exercise (LSE) with and without blood flow restriction (BFR) on the left thigh on golf performance. Eighteen amateur golfers with more than 1 year of golf experience participated in the study and were randomly divided into two groups: LSE+BFR group (LSE with BFR on the left thigh, n=9) and LSE group (LSE without BFR, n=9). The LSEs consisted of squats, lunges, and standing leg curls. All exercises were performed 3 times a week for 6 weeks. Changes in thigh muscle strength, plantar foot pressure (weight transfer), and golf performance, such as club head speed, ball speed, and carry distance were measured before and after the exercise program. Right knee extension (P<0.001) and left knee extension and flexion (P<0.001) strength were higher in the LSE+BFR group than in the LSE group. The changes in plantar foot pressure confirmed that smooth weight transfer appeared in E1 (event 1) (address) (P<0.05) of the LSE+BFR group, which confirmed that the carry distance (P<0.05) of the LSE+BFR group improved after the exercise program. The results of this study showed that BFR muscle strengthening exercise are more effective than basic simple muscle strengthening exercise in improving golf performance through muscle strength and weight transfer improvement.

The Evolution of Blood Flow Restricted Exercise

The use of blood flow restricted (BFR) exercise has become an accepted alternative approach to improve skeletal muscle mass and function and improve cardiovascular function in individuals that are not able to or do not wish to use traditional exercise protocols that rely on heavy loads and high training volumes. BFR exercise involves the reduction of blood flow to working skeletal muscle by applying a flexible cuff to the most proximal portions of a person’s arms or legs that results in decreased arterial flow to the exercising muscle and occluded venous return back to the central circulation. Safety concerns, especially related to the cardiovascular system, have not been consistently reported with a few exceptions; however, most researchers agree that BFR exercise can be a relatively safe technique for most people that are free from serious cardiovascular disease, as well as those with coronary artery disease, and also for people suffering from chronic conditions, such as multiple sclerosis, Parkinson’s, and osteoarthritis. Potential mechanisms to explain the benefits of BFR exercise are still mostly speculative and may require more invasive studies or the use of animal models to fully explore mechanisms of adaptation. The setting of absolute resistive pressures has evolved, from being based on an individual’s systolic blood pressure to a relative measure that is based on various percentages of the pressures needed to totally occlude blood flow in the exercising limb. However, since several other issues remain unresolved, such as the actual external loads used in combination with BFR, the type of cuff used to induce the blood flow restriction, and whether the restriction is continuous or intermittent, this paper will attempt to address these additional concerns.

Multiple measures of muscle function influence Sorensen Test performance in individuals with recurrent low back pain

BACKGROUND

Sorensen Test time-to-task-failure (TTF) predicts several low back pain (LBP) clinical outcomes, including recurrence. Because the test is described as a measure of trunk extensor (TE) muscle endurance, LBP rehabilitation programs often emphasize endurance training, but the direct role of TE muscle function on Sorensen Test-TTF remains unclear.

OBJECTIVE

To assess the discriminative and associative properties of multiple markers of isolated TE performance with regard to Sorensen Test-TTF in individuals with recurrent LBP.

METHOD

Secondary analysis of baseline measures from participants in a registered (NCT02308189) trial (10 men; 20 women) was performed. Participants were classified by Sorensen Test-TTF as high, moderate or low risk for subsequent LBP episodes, and compared to determine if classification could discriminate differences in TE function. Correlations between Sorensen Test-TTF and isolated TE performance, anthropometrics and disability were investigated.

RESULTS

Individuals at risk of subsequent LBP episodes had greater perceived disability and fat mass/TE strength ratios (P⩽ 0.05) than those not at risk. Modest, significant (r= 0.36-0.42, P⩽ 0.05) associations were found between Sorensen Test-TTF, TE endurance and fat mass/TE strength. Exploratory analyses suggested possible sex-specific differences related to Sorensen Test-TTF.

CONCLUSIONS

Isolated TE muscle endurance is only one of several factors with similar influence on Sorensen Test-TFF, thus LBP rehabilitation strategies should consider other factors, including TE strength, anthropometrics and perceived disability.

A Graded Exposure, Locomotion-Enabled Virtual Reality App During Walking and Reaching for Individuals With Chronic Low Back Pain: Cohort Gaming Design

BACKGROUND

Chronic low back pain (cLBP) can interfere with daily activities, and individuals with elevated pain-related fear (also known as kinesiophobia or the fear of injury due to movement) can develop worse long-term disability. Graded exposure (GEXP) protocols use successive participation in avoided activities to help individuals overcome fearful movement appraisals and encourage activity. We sought to develop a series of GEXP virtual reality (VR) walking and reaching scenarios to increase the exposure and engagement of people with high kinesiophobia and cLBP.

OBJECTIVE

This study aims to (1) determine GEXP content validity of the VR application and (2) determine the feasibility of individuals with cLBP performing locomotion-enabled physical activities.

METHODS

We recruited 13 individuals with cLBP and high pain-related fear to experience six VR modules, which provide progressive movement exposure over three sessions in a 1 week period. At session 1, participants ranked each module by likelihood to avoid and assigned an expected pain and concern for harming their back rating to each module. Participants provided a rating of perceived exertion (RPE) after experiencing each module. To test feasibility, we administered the system usability scale (SUS) and treatment evaluation inventory (TEI) following the final session. In addition, we measured pain and pain-related fear at baseline and follow-up.

RESULTS

The 12 participants who completed the study period assigned higher avoidance (P=.002), expected pain (P=.002), and expected concern (P=.002) for session 3 modules compared with session 1 modules. RPE significantly increased from session 1 (mean 14.8, SD 2.3) to session 3 (mean 16.8, SD 2.2; P=.009). The VR application showed positive feasibility for individuals with cLBP through acceptable SUS (mean 76.7, SD 13.0) and TEI (mean 32.5, SD 4.9) scores. Neither pain (P=.20) nor pain-related fear (P=.58) changed significantly across sessions.

CONCLUSIONS

The GEXP VR modules provided progressive exposure to physical challenges, and participants found the VR application acceptable and usable as a potential treatment option. Furthermore, the lack of significant change for pain and pain-related fear reflects that participants were able to complete the modules safely.

Blood Flow-restricted Exercise Does Not Induce a Cross-Transfer of Effect: A Randomized Controlled Trial

PURPOSE

The goal of this trial was to determine whether low-load blood flow-restricted (BFR) exercise of appendicular muscles induces a cross-transfer of effect to the trunk extensor (TE) muscles, such that low-load TE exercise would enhance TE size and function to a greater extent than standard low-load exercise in people with recurrent low back pain (LBP). We also investigated the direct effects of BFR exercise in the appendicular muscles.

METHODS

Thirty-two adults with recurrent, nonspecific LBP were randomized into two groups: Appendicular BFR exercise (BFR exercise) or control exercise (CON exercise). All participants trained (two times per week) for 10 wk, with a 12-wk follow-up. Participants performed three sets of leg extension (LE), plantar flexion (PF), and elbow flexion (EF) exercises followed by low-load TE exercise without BFR. Outcome measures included magnetic resonance imaging-derived muscle size (quadriceps and TE), strength (LE, PF, EF, and TE), and endurance (LE and TE).

RESULTS

There was no evidence for a cross-transfer of effect to the TE. There was also no statistically significant enhancement of limb skeletal muscle size or function of BFR relative to CON exercise at any time point; though, moderate effect sizes for BFR exercise were observed for enhanced muscle size and strength in the leg extensors.

CONCLUSIONS

Low-load BFR exercise of the appendicular muscles did not result in a cross-transfer of effect to the TE musculature. There was also no significant benefit of low-load BFR exercise on the appendicular muscle size and function, suggesting no benefit from low-load BFR exercise in adults with recurrent, nonspecific LBP.

Changes in DXA-derived lean mass and MRI-derived cross-sectional area of the thigh are modestly associated

Dual-energy X-ray absorptiometry (DXA) derived measures of lean mass demonstrate strong associations with magnetic resonance imaging (MRI) derived measures of muscle volume (MV) in cross-sectional studies, however, few studies have compared changes in response to an intervention. The purpose of this study was to determine the accuracy of DXA at detecting changes in lean mass, using MRI-derived MV as a reference standard. 10 male and 16 female subjects (29.2 ± 9.5 years) underwent DXA and MRI scans before and after a 10-week resistance training intervention. DXA thigh lean mass was compared to MRI mid-thigh MV, and percent change in size was compared between MRI and DXA. There was a strong correlation between measures cross-sectionally (r = 0.89) in agreement with previous investigations. However, there was a modest correlation of percentage change over time between methods (r = 0.49). Bland-Altman plots revealed that the amount of random error increased as the magnitude of the change from baseline increased. DXA measures of change in lean mass were modestly associated with MRI measures of change in MV. While there are several advantages to using DXA for the measurement of lean mass, the inability to accurately detect changes over time calls into question its use in clinical trials.