Increases In Muscle Hypertrophy Research Articles

P.04Resistance exercises with blood flow restriction in patients with sporadic inclusion body myositis

Sporadic inclusion body myositis (sIBM) is the most common muscle disease affecting older adults with no disease-modifying treatment. Resistance exercises increase muscle hypertrophy, but weakness prevents exercising with higher resistance. In healthy subjects, augmentation of light-load training with blood flow restriction improved muscle strength; and similar exercises were safe in the elderly. We therefore investigate whether resistance exercises with blood flow restriction is safe and helpful in sIBM patients. We explored methods for exercising weak leg muscles, and options for better outcome measures. A matched-control pilot study, with 12-week treatment and 4-week follow-up periods, where participants concentrated on lower limbs resistance exercises with 50% blood flow restriction 3 times per week, at 20%-30% of their repetition maximum. Patients are reviewed 4-weekly for muscle strength, blood biomarkers, 2-minute walk test (2MWT), timed up-and-go (TUG) test, minimal chair height standing ability test (MCHSAT), thigh girths, and quality of life scales. 4 patients with varying abilities were on the exercise arm, and 3 acted as controls. Muscle groups with MRC score ≥2 were able to be exercised. We found strength testing by hand-held dynamometer was unreliable, whereas the 2MWT, TUG test and MCHSAT showed less variability. All patients could perform their exercises at significantly increased repetitions or weights by week 4, without concerning adverse events, with trend towards continued improvement over the 4-month period. Resistance exercises with blood flow restriction appear safe, and may be helpful in sIBM patients, even in weakened muscles, enabling improvement in muscle strength and endurance.

PERBANDINGAN METODE LATIHAN PIRAMID NORMAL DAN TERBALIK TERHADAP PENINGKATAN HIPERTROFI OTOT LENGAN DAN PAHA

Sandra Arhesa dan Rudi Prodi Pendidikan Jasmani, Universitas Majalengka arhesasandra@unma.ac.id ABSTRACT This study aimed to determine the comparison between the pyramid and reverse pyramid training methods to increase arm and thigh muscle hypertrophy. This study used an experimental research method, the research design used was a pretest-posttest design, with a population of all members of BP Bumi Sangkuriang Fitness Center totaling 50 people. The sampling technique uses purvosive sampling techniques. So the sample taken was 20 people, 10 people used the pyramid training method and 10 people used the reverse pyramid training method. Instruments are meters, standing dumbell curls and leg extensions. Data Analysis Techniques by testing the mean and standard deviation, normality, homogeneity and hypothesis. The results of the analysis in this study indicate an influence on the increase in muscle hypertrophy using the pyramid and inverted pyramid training methods and there is a significant comparison between the pyramid and inverted pyramid training methods to increase muscle hypertrophy, especially the arm and thigh muscles, with improved muscle hypertrophy using Pyramid training method. It is expected that in the future research will be carried out to increase hypertrophy with the method of pyramid training and inverted pyramids on other types of muscle and more than one month of research with more samples. Keywords: Muscle Hypertrophy, Weight Training, Exercise Method, Pyramid System and Reverse Pyramid

024 Resistance exercises with blood flow restriction in patients with sporadic inclusion body myositis

IntroductionSporadic inclusion body myositis (sIBM) is the most common muscle disease affecting older adults with no disease-modifying treatment. Resistance exercises increase muscle hypertrophy, but weakness prevents exercising with higher resistance. In healthy subjects, augmentation of light-load training with blood flow restriction improved muscle strength1; and similar exercises were safe in the elderly.2 We therefore investigate whether resistance exercises with blood flow restriction is safe and helpful in sIBM patients. We explored methods for exercising weak leg muscles, and options for better outcome measures.MethodsA matched-control pilot study, with 12-week treatment and 4-week follow-up periods, where participants concentrated on lower limbs resistance exercises with 50% blood flow restriction 3 times/week, at 20%-30% of their repetition maximum. Patients are reviewed 4-weekly for muscle strength, blood biomarkers, 2-minute walk test (2MWT), timed up-and-go (TUG) test, minimal chair height standing ability test (MCHSAT), thigh girths, and quality of life scales.Results4 patients with varying abilities were on the exercise arm, and 3 acted as controls. Muscle groups with MRC score ≥2 were able to be exercised. We found strength testing by hand-held dynamometer was unreliable, whereas the 2MWT, TUG test and MCHSAT showed less variability. All patients could perform their exercises at significantly increased repetitions or weights by week 4, without concerning adverse events, with trend towards continued improvement over the 4-month period.ConclusionResistance exercises with blood flow restriction appear safe, and may be helpful in sIBM patients, even in weakened muscles, enabling improvement in muscle strength and endurance.ReferencesHughes L, Paton B, Rosenblatt B, Gissane C, Patterson SD. Blood flow restriction training in clinical musculoskeletal rehabilitation: a systematic review and meta-analysis. Br J Sports 2017.Vechin FC, Libardi CA, Conceicao MS, et al. Comparisons between low-intensity resistance training with blood flow restriction and high-intensity resistance training on quadriceps muscle mass and strength in elderly. J Strength Cond Res 2015.

Effects of Novel Compression Exercise Technology on Glycohemoglobin Levels and Weight in Type II Diabetics

The most potent lifestyle intervention for treatment of Type II Diabetes (T2D) is consistent exercise. However, for many patients with the condition, other comorbidities such as osteoarthritis, hypertension, and high body mass indexes prevent them from being able to exercise intensively and consistently enough to experience optimal metabolic benefits. Recent research has supported the use of compression exercise in physically limited populations and demonstrated physiologic responses at lower intensities (10-20% one repetition maximum vs. 70% for hypertrophic response in conventional resistance exercise). The combination of compression technology with core cooling further lowers the exertional requirements and has been used in cardiopulmonary rehabilitation populations to provide a safe and reliable exercise intervention. Compression exercise has also been shown to significantly increase muscle hypertrophy, with a greater growth in type II fibers (higher expressers of GLUT4). Therefore, this technology could directly address basal metabolism through increasing muscle protein turnover, increasing glucose storage in skeletal muscle mass, and improving glycemic control. This capacity to attenuate the insulin response combined with the accessibility of the platform suggests a clinical implication for diabetes management. PURPOSE: To establish safe use of cooled compressive exercise in Type II Diabetics and to examine the effect of 6 months of training on biometabolic markers, especially Glycohemoglobin levels and weight. METHODS: Thirty Type II Diabetics agreed to 3 training sessions a week for 6 months. Biometabolic markers via blood draw were analyzed at 0, 3, and 6 months. RESULTS: Midpoint data from 16 participants at 0 and 3 months were analyzed with a two-tailed T-test, revealing significant differences in Glycohemoglobin and weight. There was an 8% average decrease in Glycohemoglobin levels (8.5±2.2 vs. 7.8±1.8 mg/dl, p = 0.002) and an average weight loss of 3.6 lbs (211±50 vs. 208±48 lbs, p = 0.032). CONCLUSION: The preliminary results of this study suggest exercise with compression and cooling contributes to a reduction in biometabolic markers of diabetes. This intervention has promise in contributing to effective management of T2D with a low physical burden.

Brief Review: Effects of Isometric Strength Training on Strength and Dynamic Performance.

This review used a narrative summary of findings from studies that focused on isometric strength training (IST), covering the training considerations that affect strength adaptations and its effects on sports related dynamic performances. IST has been shown to induce less fatigue and resulted in superior joint angle specific strength than dynamic strength training, and benefited sports related dynamic performances such as running, jumping and cycling. IST may be included into athletes' training regime to avoid getting overly fatigue while still acquiring positive neuromuscular adaptations; to improve the strength at a biomechanically disadvantaged joint position of a specific movement; to improve sports specific movements that require mainly isometric contraction; and when athletes have limited mobility due to injuries. To increase muscle hypertrophy, IST should be performed at 70-75% of maximum voluntary contraction (MVC) with sustained contraction of 3-30 s per repetition, and total contraction duration of>80-150 s per session for>36 sessions. To increase maximum strength, IST should be performed at 80-100% MVC with sustained contraction of 1-5 s, and total contraction time of 30-90 s per session, while adopting multiple joint angles or targeted joint angle. Performing IST in a ballistic manner can maximize the improvement of rate of force development.

Effects of order of resistance training exercises on muscle hypertrophy in young adult men

The purpose of the present study was to analyze the effects of the order of resistance training (RT) exercises on hypertrophy in young adult men. Thirty-six young adult men (age, 21.9 ± 2.5 years; body mass, 72.6 ± 12.1 kg, height, 176.9 ± 7.4 cm; body mass index, 23.1 ± 3.3 kg/m2) were randomly assigned to 1 of 2 training groups that performed a 6-week RT program in either (i) a traditional approach starting with multi-joint (MJ) exercises followed by single-joint exercises (SJ) (MJ-SJ, n = 19) or (ii) in reverse order (SJ-MJ, n = 17). Muscle thickness of the biceps brachii and mid-thigh were assessed by ultrasound. Lean soft tissue (LST) was assessed by dual-energy X-ray absorptiometry. Both groups similarly increased (P < 0.05) biceps brachii thickness (MJ-SJ = +14.2%, SJ-MJ = +13.8%). Alternatively, only the MJ-SJ group presented an increase in mid-thigh thickness from pre- to post-training (MJ-SJ = +7.2%, SJ-MJ = +3.9%). Upper limb LSTs (MJ-SJ = +5.2%, SJ-MJ = +7.5%) were statistically similar between conditions, and a trend for significance (P = 0.07) was found for trunk LST (MJ-SJ = +7.2%, SJ-MJ = +1.7%). Nonsignificant pre- to post-training changes were observed for lower limb LSTs (MJ-SJ = +0.7%, SJ-MJ = +1.8%). Our data suggest that both sequences are effective for increasing muscle hypertrophy over a short-term RT period; there may be a potentially beneficial hypertrophic effect for the mid-thigh by performing exercises in a manner that progresses from MJ to SJ exercises.

Effects of Insect Protein Supplementation during Resistance Training on Changes in Muscle Mass and Strength in Young Men.

During prolonged resistance training, protein supplementation is known to promote morphological changes; however, no previous training studies have tested the effect of insect protein isolate in a human trial. The aim of this study was to investigate the potential effect of insect protein as a dietary supplement to increase muscle hypertrophy and strength gains during prolonged resistance training in young men. Eighteen healthy young men performed resistance training four day/week for eight weeks. Subjects were block randomized into two groups consuming either an insect protein isolate or isocaloric carbohydrate supplementation within 1 h after training and pre-sleep on training days. Strength and body composition were measured before and after intervention to detect adaptions to the resistance training. Three-day weighed dietary records were completed before and during intervention. Fat- and bone- free mass (FBFM) improved significantly in both groups (Mean (95% confidence interval (CI))), control group (Con): (2.5 kg (1.5, 3.5) p < 0.01), protein group (Pro): (2.7 kg (1.6, 3.8) p < 0.01) from pre- to post- leg and bench press one repetition maximum (1 RM) improved by Con: (42.0 kg (32.0, 52.0) p < 0.01) and (13.8 kg (10.3, 17.2) p < 0.01), Pro: (36.6 kg (27.3, 45.8) p < 0.01) and (8.1 kg (4.5, 11.8) p < 0.01), respectively. No significant differences in body composition and muscle strength improvements were found between groups. In young healthy men, insect protein supplementation did not improve adaptations to eight weeks of resistance training in comparison to carbohydrate supplementation. A high habitual protein intake in both Con and Pro may partly explain our observation of no superior effect of insect protein supplementation.

Magnetic Resonance Imaging Predicts Histopathological Composition of Ileal Crohn's Disease.

Recently, smooth muscle hypertrophy has been suggested to be a contributor to small bowel lesions secondary to Crohn's disease [CD], in addition to inflammation and fibrosis. Here, we assess the value of magnetic resonance imaging [MRI] for the characterisation of histopathological tissue composition of small bowel CD, including inflammation, fibrosis, and smooth muscle hypertrophy. A total of 35 consecutive patients [male/female 17/18, mean age 33 years] with ileal CD, who underwent small bowel resection and a preoperative contrast-enhanced MRI examination within 1 month before surgery, were retrospectively included. Image assessment included qualitative [pattern/degree of enhancement, presence of ulcerations/fistulas/abscesses] and quantitative parameters [wall thickness on T2/T1-weighted images [WI], enhancement ratios, apparent diffusion coefficient [ADC], Clermont and Magnetic Resonance Index of Activity [MaRIA] scores). MRI parameters were compared with histopathological findings including active inflammation, collagen deposition, and muscle hypertrophy using chi square/Fisher or Mann-Whitney tests and univariate/multivariate logistic/linear regression analyses. Forty ileal segments were analysed in 35 patients. Layered pattern at early-post-contrast phase was more prevalent (odds ratio [OR] = 8; p = 0.008), ADC was significantly lower [OR = 0.005; p = 0.022], and MaRIA score was significantly higher [OR = 1.125; p = 0.022] in inflammation grades 2-3 compared with grade 1. Wall thickness on T2WI was significantly increased [OR = 1.688; p = 0.043], and fistulas [OR = 14.5; p = 0.017] were more prevalent in segments with disproportionately increased muscle hypertrophy versus those with disproportionately increased fibrosis. MaRIA/Clermont scores, wall thickness on T1WI and T2WI, and ADC were all significantly correlated with degree of muscular hypertrophy. MRI predicts the degree of inflammation, and can distinguish prominent muscle hypertrophy from prominent fibrosis in ileal CD with reasonable accuracy (area under receiver operating characteristic curve [AUROC] > 0.7).

Effects of a Modified German Volume Training Program on Muscular Hypertrophy and Strength.

Amirthalingam, T, Mavros, Y, Wilson, GC, Clarke, JL, Mitchell, L, and Hackett, DA. Effects of a modified German volume training program on muscular hypertrophy and strength. J Strength Cond Res 31(11): 3109-3119, 2017-German Volume Training (GVT), or the 10 sets method, has been used for decades by weightlifters to increase muscle mass. To date, no study has directly examined the training adaptations after GVT. The purpose of this study was to investigate the effect of a modified GVT intervention on muscular hypertrophy and strength. Nineteen healthy men were randomly assign to 6 weeks of 10 or 5 sets of 10 repetitions for specific compound resistance exercises included in a split routine performed 3 times per week. Total and regional lean body mass, muscle thickness, and muscle strength were measured before and after the training program. Across groups, there were significant increases in lean body mass measures, however, greater increases in trunk (p = 0.043; effect size [ES] = -0.21) and arm (p = 0.083; ES = -0.25) lean body mass favored the 5-SET group. No significant increases were found for leg lean body mass or measures of muscle thickness across groups. Significant increases were found across groups for muscular strength, with greater increases in the 5-SET group for bench press (p = 0.014; ES = -0.43) and lat pull-down (p = 0.003; ES = -0.54). It seems that the modified GVT program is no more effective than performing 5 sets per exercise for increasing muscle hypertrophy and strength. To maximize hypertrophic training effects, it is recommended that 4-6 sets per exercise be performed, as it seems gains will plateau beyond this set range and may even regress due to overtraining.

Hypertrophic Effects of Concentric vs. Eccentric Muscle Actions: A Systematic Review and Meta-analysis.

Schoenfeld, BJ, Ogborn, DI, Vigotsky, AD, Franchi, MV, and Krieger, JW. Hypertrophic effects of concentric vs. eccentric muscle actions: A systematic review and meta-analysis. J Strength Cond Res 31(9): 2599-2608, 2017-Controversy exists as to whether different dynamic muscle actions produce divergent hypertrophic responses. The purpose of this paper was to conduct a systematic review and meta-analysis of randomized controlled trials comparing the hypertrophic effects of concentric vs. eccentric training in healthy adults after regimented resistance training (RT). Studies were deemed eligible for inclusion if they met the following criteria: (a) were an experimental trial published in an English-language refereed journal; (b) directly compared concentric and eccentric actions without the use of external implements (i.e., blood pressure cuffs) and all other RT variables equivalent; (c) measured morphologic changes using biopsy, imaging (magnetic resonance imaging, computerized tomography, or ultrasound), bioelectrical impedance, and/or densitometry; (d) had a minimum duration of 6 weeks; and (e) used human participants without musculoskeletal injury or any health condition that could directly, or through the medications associated with the management of said condition, be expected to impact the hypertrophic response to resistance exercise. A systematic literature search determined that 15 studies met inclusion criteria. Results showed that eccentric muscle actions resulted in a greater effect size (ES) compared with concentric actions, but results did not reach statistical significance (ES difference = 0.25 ± 0.13; 95% confidence interval: -0.03 to 0.52; p = 0.076). The mean percent change in muscle growth across studies favored eccentric compared with concentric actions (10.0% vs. 6.8, respectively). The findings indicate the importance of including eccentric and concentric actions in a hypertrophy-oriented RT program, as both have shown to be effective in increasing muscle hypertrophy.

THE EFFECT OF CAFFEINE SUPPLEMENTATION ON TRAINED INDIVIDUALS SUBJECTED TO MAXIMAL TREADMILL TEST.

Background:Intense physical training increases oxidative stress and inflammation, resulting into muscle and cellular damage. The aim of this study was to analyze the effect of caffeine supplementation on trained young individuals subjected to two treadmill maximal tests.Materials and Methods:It was a double-blind and crossover study comprising 24 active individuals within the age group 18-30 years. The comparisons were conducted: the effect of exercise (week 1 x 2) and caffeine intake (GC x GP) on thiobarbituric acid (TBARS), interleukin 6 (IL-6), interleukin 10 (IL-10) and superoxide dismutase (SOD) variables during pre-exercise time (30 min. after caffeine or placebo intake) and post-exercise (5 min after treadmill test).Results:The comparison between weeks 1 and 2 showed increase in the first week, in the following items: TBARS, IL-6 and IL-10 in the GC and GP groups. The comparison within the same week showed that GC individuals presented lower post-exercise TBARS values in the first and second weeks; IL- 6 presented higher post-exercise values in the GC group in both weeks. The paired analysis comparing pre- and post-exercise, with and without caffeine showed that IL-6 presented higher post-exercise values in the GC group.Conclusion:Caffeine used by athletes can decrease oxidative stress. The increased IL-6 suggest that this ergogenic supplement may stimulate muscle hypertrophy, since IL-6 has myokine effect. However, the caffeine effect on IL-6 level and muscle hypertrophy increase should be better investigated in future studies.

Peripheral Electrical and Magnetic Stimulation to Augment Resistance Training

Electrical stimulation (ES) and magnetic stimulation (MS), applied peripherally, may be used to elicit muscle contractions to increase muscle hypertrophy, increase muscle strength and reduce knee laxity in rehabilitation following injury. We aimed to examine the effect of a three-week exercise programme designed to induce muscle hypertrophy augmented by peripheral ES and MS. We hypothesised that the use of peripheral stimulation to augment voluntary drive during a resistance-training protocol would induce more repetitions thus leading to increased thigh circumference, muscle layer thickness, and quadriceps strength whilst decreasing knee laxity. Thirty healthy participants were divided randomly into either ES, MS or Control groups. Five resistance training sessions were carried out, consisting of four sets of quadriceps extensions. During the first three sets the participants performed eight repetitions at 85% of their 1-repetition maximum (1-RM). On the last set, the participants were instructed to perform the exercise until failure. The augmentation of peripheral stimuli allowed the MS and ES groups to continue to exercise producing, on average, 4 ± 2 and 7 ± 6 additional repetitions with ES and MS, respectively. Following the training, significant increases were observed for both 1-RM (p = 0.005) and muscle layer thickness (p = 0.031) whilst no change was observed in thigh circumference (p = 0.365). Knee laxity decreased (p = 0.005). However, there were no significant differences in the stimulation groups compared with control for any of these measurements. The additional repetitions elicited by stimulation after the point of failure suggests that peripheral electrical and/or magnetic stimulation may be useful as an adjunct for resistance training. However, this effect of resistance training augmented by peripheral stimulation on hypertrophy, strength and knee laxity may be small.

Effects of Low- vs. High-Load Resistance Training on Muscle Strength and Hypertrophy in Well-Trained Men.

The purpose of this study was to compare the effect of low- versus high-load resistance training (RT) on muscular adaptations in well-trained subjects. Eighteen young men experienced in RT were matched according to baseline strength and then randomly assigned to 1 of 2 experimental groups: a low-load RT routine (LL) where 25-35 repetitions were performed per set per exercise (n = 9) or a high-load RT routine (HL) where 8-12 repetitions were performed per set per exercise (n = 9). During each session, subjects in both groups performed 3 sets of 7 different exercises representing all major muscles. Training was performed 3 times per week on nonconsecutive days, for a total of 8 weeks. Both HL and LL conditions produced significant increases in thickness of the elbow flexors (5.3 vs. 8.6%, respectively), elbow extensors (6.0 vs. 5.2%, respectively), and quadriceps femoris (9.3 vs. 9.5%, respectively), with no significant differences noted between groups. Improvements in back squat strength were significantly greater for HL compared with LL (19.6 vs. 8.8%, respectively), and there was a trend for greater increases in 1 repetition maximum (1RM) bench press (6.5 vs. 2.0%, respectively). Upper body muscle endurance (assessed by the bench press at 50% 1RM to failure) improved to a greater extent in LL compared with HL (16.6 vs. -1.2%, respectively). These findings indicate that both HL and LL training to failure can elicit significant increases in muscle hypertrophy among well-trained young men; however, HL training is superior for maximizing strength adaptations.

Functional animal proteins activate mTOR and bind pro-inflammatory compounds

Background Protein supplementation in addition to resistance training has been shown to increase muscle hypertrophy and lean mass. Supplemental protein sources differ in amino acid composition, size, structure, and functionality. Animal derived proteins sources such as Beef Protein Isolate (BeefISO), Serum Albumin Concentrate (SuperSerum), Serum Protein Concentrate (SerumPro), whey protein isolate (WPI), and hydrolyzed Chicken Protein Isolate (MyoCHX) each have high-quality amino acid profiles. The mammalian target of rapamycin (mTOR) signal pathway is a nutrient sensor whose activation is associated with muscle protein synthesis. In this work, mTOR pathway activation was shown by Western blot to demonstrate bioavailability of protein preparations. Protein functionality was demonstrated by lipopolysaccharide (LPS) binding to prevent antigen induced inflammatory signaling. Systemic inflammation has been shown to negatively impact athletic performance, suggesting protein preparations which can stimulate muscle protein synthesis and reduce inflammation may be advantageous following resistance training.

G.P.108 - ACE-083 increases muscle hypertrophy and strength in C57BL/6 mice

G.P.108 - ACE-083 increases muscle hypertrophy and strength in C57BL/6 mice

Volume-Equated High and Low Repetition Daily Undulating Periodization Models for Upper Body Muscle Hypertrophy

Traditionally, 8-12 repetitions have been recommended to maximize muscle hypertrophy. However, recent research suggests total training volume independent of specific repetition ranges is the most important variable for hypertrophy. Despite this, volume-equated daily undulating periodization (DUP) models with various repetition ranges have yet to be investigated for hypertrophy. PURPOSE: To compare changes in muscle hypertrophy in high repetition daily undulating periodization (DUP-HR) and low repetition daily undulating periodization (DUP-LR), models. METHODS: Fifteen males (age: 22.9±3.0 yrs, weight: 83.3±12.0kg., body fat: 11.2±4.5%) with a minimum of 2yrs. resistance training experience, and a frequency of ≥ 1 day/wk. bench press over the past 6 months were assigned to one of two DUP groups: 1) DUP-HR (n=7): 12 repetitions (Mon), 10 repetitions (Wed), and 8 repetitions (Fri) or 2) DUP-LR (n=8): 6 repetitions (Mon), 4 repetitions (Wed), and 2 repetitions (Fri). Subjects performed the bench press exercise each session. The study spanned 8 total weeks. Week 1 served as pre-testing and introductory training, weeks 2-7 serving as the main training program, and week 8 a taper training week and post-testing. Hypertrophy was assessed pre- and post-training by muscle thickness (MT) via ultrasonography (BodyMetrix, IntelaMetrix, Livermore, CA.). MT measurements were taken of the left chest and right chest and then summed for total chest MT. A 2 x 2 repeated measures ANOVA was used with significance set at p≤0.05. RESULTS: Both groups increased (p<0.05) chest MT (DUP-HR-pre: 72.33±8.64mm - post: 78.78± 7.41mm and DUP-LR-pre: 74.63±13.96mm- post: 82.71±17.22mm), however there were no group differences (p>0.05). Percent changes from pre to post-testing were +10.8% and +8.9% in DUP-LR and DUP-HR respectively. CONCLUSION: Our findings demonstrate that DUP is an effective method to increase muscle hypertrophy over a short-term training program in previously trained individuals. Further, this data suggests that muscle hypertrophy is volume-dependent and not determined by a specific repetition range.

Walking‐mediated upregulation of follistatin‐like 3 expression is insufficient to increase muscle contractile force

Molecular mechanisms coordinating muscle and bone strength and growth with exercise (EX) are undefined. EX upregulates follistatin‐like 3 (FSTL3) in mouse and human skeletal muscle, bone and serum, and FSTL3 is required for EX‐driven bone formation (Nam, 2014, in press). FSTL3 is known to bind and inhibit myostatin. Thus, our purpose was to determine if FSTL3 increases muscle hypertrophy and force generation through this mechanism to collectively regulate musculoskeletal function. Wild‐type (WT) or Fstl3‐/‐ C57/Bl6 mice (n=30) were treadmill walked for 45 min/day at 8 m/min for 6 weeks, a protocol that increases bone formation. Muscles were mounted between stimulating electrodes, equilibrated at max force, then stimulated from 1‐150 hz to generate force vs. frequency curves. No differences in force were observed in WT EX and WT NoEX, indicating that walking was not sufficiently rigorous to produce a training effect on muscle force. No force differences were observed in Fstl3‐/‐ EX and Fstl3‐/‐ NoEX. Endogenous FSTL3 may not be sufficient to alter muscle contractile force generation in response to walking. FSTL3 regulates bone health in response to walking EX; however, walking is insufficient to increase muscle force and hypertrophy. While walking may be prescribed as a treatment regimen for increasing bone growth in humans, clinicians should be aware that walking may need to be supplemented with a resistance EX program to increase muscle strength/hypertrophy.

Resistance exercise load reduction and exercise-induced micro-damage

Silva, J.S., Koch, A.J., Medeiros, J.C., Da Silva M.L., & Machado, M. (2014). Resistance exercise load reduction and exercise-induced micro-damage. J. Hum. Sport Exerc., 9(1), pp.1-6. High volumes of resistance exercise increase muscle hypertrophy, independent of the extent of muscle damage. We compared volume load and markers of muscle damage after resistance exercise using two load reduction strategies versus a constant intensity. Methods: Twenty-seven trained men (age = 23.4±3.5 years, body mass = 74.5±10.7 Kg, height = 174±8 cm, 10 RM = 211±40 Kg) completed one weekly bout of 4 sets of leg press exercise under three loading schemes in a randomized, counterbalanced order over a three-week period. The loading schemes were (a) constant load for all sets (CON), (b) 5% load reduction after each set (LR5), and (c) 10% load reduction after each set (LR10). Volume load, muscle soreness (SOR), and range of motion (ROM) at the knee were assessed after each bout. Results: Volume load was significantly different amongst all conditions (CON = 6799±1583 Kg; LR5 = 8753±1789 Kg; 10896±2262 Kg; F= 31,731; p<0.001). ROM and SOR were significantly different among conditions, with LR5 and LR10 producing greater preservations of ROM (p =<0.001) and less SOR (p < 0.001). These data may support the use of load reductions when training for hypertrophy. Key words: RESISTANCE TRAINING, EXERCISE-INDUCED MUSCLE-DAMAGE, RANGE OF MOTION, PAIN

Influence of divergent exercise contraction mode and whey protein supplementation on atrogin-1, MuRF1, and FOXO1/3A in human skeletal muscle

Knowledge from human exercise studies on regulators of muscle atrophy is lacking, but it is important to understand the underlying mechanisms influencing skeletal muscle protein turnover and net protein gain. This study examined the regulation of muscle atrophy-related factors, including atrogin-1 and MuRF1, their upstream transcription factors FOXO1 and FOXO3A and the atrogin-1 substrate eIF3-f, in response to unilateral isolated eccentric (ECC) vs. concentric (CONC) exercise and training. Exercise was performed with whey protein hydrolysate (WPH) or isocaloric carbohydrate (CHO) supplementation. Twenty-four subjects were divided into WPH and CHO groups and completed both single-bout exercise and 12 wk of training. Single-bout ECC exercise decreased atrogin-1 and FOXO3A mRNA compared with basal and CONC exercise, while MuRF1 mRNA was upregulated compared with basal. ECC exercise downregulated FOXO1 and phospho-FOXO1 protein compared with basal, and phospho-FOXO3A was downregulated compared with CONC. CONC single-bout exercise mediated a greater increase in MuRF1 mRNA and increased FOXO1 mRNA compared with basal and ECC. CONC exercise downregulated FOXO1, FOXO3A, and eIF3-f protein compared with basal. Following training, an increase in basal phospho-FOXO1 was observed. While WPH supplementation with ECC and CONC training further increased muscle hypertrophy, it did not have an additional effect on mRNA or protein levels of the targets measured. In conclusion, atrogin-1, MuRF1, FOXO1/3A, and eIF3-f mRNA, and protein levels, are differentially regulated by exercise contraction mode but not WPH supplementation combined with hypertrophy-inducing training. This highlights the complexity in understanding the differing roles these factors play in healthy muscle adaptation to exercise.

Practical blood flow restriction training increases muscle hypertrophy during a periodized resistance training programme

Resistance training in combination with practical blood flow restriction (pBFR) is thought to stimulate muscle hypertrophy by increasing muscle activation and muscle swelling. Most previous studies used the KAATSU device; however, little long-term research has been completed using pBFR. To investigate the effects of pBFR on muscle hypertrophy. Twenty college-aged male participants with a minimum of 1 year of resistance training experience were recruited for this study. Our study consisted of a randomized, crossover protocol consisting of individuals either using pBFR for the elbow flexors during the first 4 weeks (BFR-HI) or the second 4 weeks (HI-BFR) of an 8-week resistance training programme. Direct ultrasound-determined bicep muscle thickness was assessed collectively at baseline and at the end of weeks 4 and 8. There were no differences in muscle thickness between groups at baseline (P = 0·52). There were time (P<0·01, ES = 0·99) but no condition by time effects (P = 0·58, ES = 0·80) for muscle thickness in which the combined values of both groups increased on average from week 0 (3·66 ± 0·06) to week 4 (3·95 ± 0·05) to week 8 (4·11 ± 0·07). However, both the BFR-HI and HI-BFR increased significantly from baseline to week 4 (6·9% and 8·6%, P<0·01) and from weeks 4 to 8 (4·1%, 4·0%, P<0·01), respectively. The results of this study suggest that pBFR can stimulate muscle hypertrophy to the same degree to that of high-intensity resistance training.