The Effect of Resistance Training in Healthy Adults on Body Fat Percentage, Fat Mass and Visceral Fat: A Systematic Review and Meta-Analysis.

BACKGROUND: Resistance training is the gold standard exercise mode for accrual of lean muscle mass, but the isolated effect of resistance training on body fat is unknown. OBJECTIVES: This systematic review and meta-analysis evaluated resistance training for body composition outcomes in healthy adults. Our primary outcome was body fat percentage; secondary outcomes were body fat mass and visceral fat. DESIGN: Systematic review with meta-analysis. DATA SOURCES: We searched five electronic databases up to January 2021. ELIGIBILITY CRITERIA: We included randomised trials that compared full-body resistance training for at least 4 weeks to no-exercise control in healthy adults. ANALYSIS: We assessed study quality with the TESTEX tool and conducted a random-effects meta-analysis, with a subgroup analysis based on measurement type (scan or non-scan) and sex (male or female), and a meta-regression for volume of resistance training and training components. RESULTS: From 11,981 records, we included 58 studies in the review, with 54 providing data for a meta-analysis. Mean study quality was 9/15 (range 6-15). Compared to the control, resistance training reduced body fat percentage by - 1.46% (95% confidence interval - 1.78 to - 1.14, p < 0.0001), body fat mass by - 0.55 kg (95% confidence interval - 0.75 to - 0.34, p < 0.0001) and visceral fat by a standardised mean difference of - 0.49 (95% confidence interval - 0.87 to - 0.11, p = 0.0114). Measurement type was a significant moderator in body fat percentage and body fat mass, but sex was not. Training volume and training components were not associated with effect size. Resistance training reduces body fat percentage, body fat mass and visceral fat in healthy adults. STUDY REGISTRATION: osf.io/hsk32.

Core stability exercises in individuals with and without chronic nonspecific low back pain.

Marshall, PWM, Desai, I, and Robbins, DW. Core stability exercises in individuals with and without chronic nonspecific low back pain. J Strength Cond Res 25(12): 3404-3411, 2011-The aim of this study was to measure trunk muscle activity during several commonly used exercises in individuals with and without low back pain (LBP). Abdominal bracing was investigated as an exercise modification that may increase the acute training stimulus. After an initial familiarization session, 10 patients with LBP and 10 matched controls performed 5 different exercises (quadruped, side bridge, modified push-up, squat, shoulder flexion) with and without abdominal bracing. Trunk muscle activity and lumbar range of motion (LROM) were measured during all exercises. Muscle activity was measured bilaterally during each exercise from rectus abdominis (RA), external obliques (EO), and lumbar erector spinae (ES) with pairs of surface electrodes. Recorded signals were normalized to a percentage of maximal voluntary contractions performed for each muscle. The ES activity was lower for the LBP group during the quadruped (p < 0.05) and higher for RA and EO during the side bridge (p < 0.001), compared to for the healthy controls. Higher muscle activity was observed across exercises in an inconsistent pattern when abdominal bracing was used during exercise. The LROM was no different between groups for any exercise. The lack of worsening of symptoms in the LBP group and similar LROM observed between groups suggest that all exercises investigated in this study are of use in rehabilitating LBP patients. The widespread use of abdominal bracing in clinical practice, whether it be for patients with LBP or healthy individuals, may not be justified unless symptoms of spinal instability are identified.

Acute effect of labile surfaces during core stability exercises in people with and without low back pain.

OBJECTIVE: The purpose of this study was to measure trunk muscle activity, whole body balance, and lumbar range of motion during core stability exercises in individuals with and without low back pain (LBP) on and off a labile surface. DESIGN: Descriptive cross-sectional study. SETTING: University laboratory. PARTICIPANTS: Ten individuals with chronic non-specific LBP and 10 matched control subjects. MAIN OUTCOME MEASURES: Bilateral trunk muscle activity was measured using surface electromyography (EMG); whole body balance was measured by quantifying the dispersion of the centre of pressure (CoP); lumbar range of motion (LROM) was measured with single-axis inclinometers. RESULTS: Individuals with LBP had adaptive recruitment patterns during the side-bridge and modified push-up exercises. CoP dispersion and LROM were not different between groups for any exercise. The labile surface did not change the difference between groups, and only increased muscle activity during the side-bridge (p<0.05). The labile surface increased LROM (p=0.35) and CoP dispersion (p<0.001) during the quadruped, decreased LROM during squats (p=0.05), and increased CoP dispersion during push-ups (p=0.04). CONCLUSION: Individuals with LBP exhibited adaptive trunk muscle activity levels while maintaining similar levels of balance and lumbar movement to healthy controls. Since research suggests no one mode of exercise is more beneficial in LBP rehabilitation, the practicality and safety of labile surfaces for LBP exercise rehabilitation must be questioned from this study.

Electromyographic analysis of upper body, lower body, and abdominal muscles during advanced Swiss ball exercises.

Although there is now some evidence examining the use of a Swiss ball during core stability and resistance exercises, this has commonly been performed using basic or isometric exercises. There is currently no evidence examining more advanced Swiss ball exercises. The purpose of this study was to determine whether or not muscle activity measured during advanced Swiss ball exercises was at an approximate intensity recommended for strength or endurance training in advanced, or novice individuals. After a familiarization session, 14 recreationally active subjects performed 6 different "advanced" Swiss ball exercises in a randomized order. The primary dependent variables in this study were the activity levels collected from anterior deltoid, pectoralis major, rectus abdominis (RA), external obliques, lumbar erector spinae, vastus lateralis (VL), and biceps femoris using surface electromyography. All signals were normalized to maximal voluntary isometric contractions performed before testing for each muscle. The results of this study showed that the Swiss ball roll elicited muscle activity in triceps brachii (72.5+/-32.4%) and VL (83.6+/-44.2%) commensurate with the intensity recommended for strength exercises in advanced trainers. Rectus abdominis activity was greatest during the bridge exercise (61.3+/-28.5%, p