The Effect of 12 Weeks of Strength Training on Muscular Strength, Body Fat Percentage, Irisin and BDNF in Active Middle-aged Women

Background: Given the secretion of myokines from muscle tissue during exercise and their relationship with muscle strength development, the present study aimed to investigate the relationship between muscle strength and serum levels of irisin, brain-derived neurotrophic factor, myostatin and follistatin in inactive men and women following 12 weeks of strength training.Methods: In this quasi-experimental study, 10 women (age: 37.66.09years, weight: 80.520.76kg) and 20 men (age: 39.66.05years, weight: 84.895.67 kg) voluntarily participated.The subjects performed 12 weeks of strength training, 3 sessions per week, with an intensity of 65 to 80% of maximum strength.Blood samples were taken for measurement of irisin, brain-derived neurotrophic factor, myostatin, and follistatin by ELISA. Results:Strength training significantly increased serum irisin, serum BDNF, follistatin and significantly decreased myostatin and fat percentage in both male and female groups (p0.05).There was also a positive and significant relationship between lower body strength and irisin in women (p=0.040) and upper body strength in women and BDNF (p=0.038).The results in the male group showed a significant and positive relationship between serum irisin levels with upper and lower body strength and follistatin with lower body strength (p0.05). Conclusion:According to the results of the study, strength training in inactive individuals reduces serum levels of myostatin , increases secretion and serum levels of irisin, BDNF, follistatin, and increases muscle strength.

The evidence for neural mechanisms underpinning rapid strength increases has been investigated and discussed for over 30 years using indirect methods, such as surface electromyography, with inferences made toward the nervous system. Alternatively, electrical stimulation techniques such as the Hoffman reflex, volitional wave, and maximal wave have provided evidence of central nervous system changes at the spinal level. For 25 years, the technique of transcranial magnetic stimulation (TMS) has allowed for noninvasive supraspinal measurement of the human nervous system in a number of areas such as fatigue, skill acquisition, clinical neurophysiology, and neurology. However, it has only been within the last decade that this technique has been used to assess neural changes after strength training. The aim of this brief review is to provide an overview of TMS, discuss specific strength training studies that have investigated changes, after short-term strength training in healthy populations in upper and lower limbs, and conclude with further research suggestions and the application of this knowledge for the strength and conditioning coach.

The effect that aerobic (AT) and/or strength training (ST) has on altering peak aerobic power (VO2peak), muscle strength, left ventricular (LV) morphology, and diastolic filling in healthy older women is not known. We assessed the effects of 12 weeks of AT, ST, combined aerobic and strength training (COMT), or no training (NT) on VO2peak, muscle strength, LV morphology, and diastolic filling in 31 healthy women (68 +/- 4 years). Relative VO2peak was significantly greater after 12 weeks of AT, ST, or COMT. Upper and lower extremity strength were significantly higher after 12 weeks of ST or COMT with no change after AT or NT. LV morphology and diastolic filling were not altered after 12 weeks of AT, ST, COMT, or NT. Twelve weeks of ST or COMT are as effective as 12 weeks of AT for increasing relative VO2peak, however, ST and COMT are more effective than AT for improving overall muscle strength.

Background: Scientific literature suggests that different types of training can have different effects on secretion of irisin and myostatin.Objectives: The purpose of this study was to determine the effect of resistance exercise training (RET), aerobic exercise training (AET) and concurrent (aerobic + resistance) exercise training (CET) on serum irisin and myostatin in untrained women.Methods: Thirty-five non-obese, untrained women were randomly assigned to control (n = 6, age 25.50 ± 4.80 years), RET (n = 10, age 24.60 ± 2.45 years), AET (n = 9, age 24.66 ± 2.29 years) or CET (n = 10, age 26.60 ± 4.00 years) groups. Subjects in training groups trained for 8 weeks, three times per week. The levels of serum irisin, myostatin were measured before and after the training period. Results: It was found that the CET group had significantly reduced serum irisin (p = .028) and myostatin (p = .005) concentrations. The myostatin concentration was also significantly decreased in the RET group (p = .008). Conclusion: CET, AET or RET were not effective for improving (increase) irisin circulating level. In addition, RET and CET were more effective than AET in reducing circulating myostatin levels.

Changes in motor unit discharge patterns following strength training.

The objectives of this study were to examine the effects of a moderate intensity strength training on changes in critical velocity (CV), anaerobic running distance (D'), sprint performance and Yo-Yo intermittent running test (Yo-Yo IR1) performances. Methods: two recreational soccer teams were divided in a soccer training only group (SO; n = 13) and a strength and soccer training group (ST; n = 13). Both groups were tested for values of CV, D', Yo-Yo IR1 distance and 30-m sprint time on two separate occasions (pre and post intervention). The ST group performed a concurrent 6-week upper and lower body strength and soccer training, whilst the SO group performed a soccer only training. Results: after the re-test of all variables, the ST demonstrated significant improvements for both, YoYo IR1 distance (p = 0.002) and CV values (p<0.001) with no significant changes in the SO group. 30-m sprint performance were slightly improved in the ST group with significantly decreased performance times identified in the SO group (p<0.001). Values for D' were slightly reduced in both groups (ST -44.5 m, 95% CI = -90.6 to 1.6; SO -42.6 m, 95% CI = -88.7 to 3.5). Conclusions: combining a 6-week moderate strength training with soccer training significantly improves CV, Yo-Yo IR1 whilst moderately improving 30-m sprint performances in non-previously resistance trained male soccer players. Critical Velocity can be recommended to coaches as an additional valid testing tool in soccer.

BackgroundIt is suspected that hormonal fluctuations during menstruation may cause different responses to strength training in women who use oral contraceptives (OC) versus those who do not. However, previous studies that investigated the existence of such differences produced conflicting results. In this study, we hypothesized that OC use has no effect on muscle strength and hypertrophy among women undergoing strength training. Thus, we compared the differences in muscle strength and thickness among women who used OCs and those who did not.MethodsWe investigated the influence of OC use on muscle strength (Fmax), muscle thickness (Mtk), type 1-to-type 2 muscle fiber (NO) ratio, muscle fiber thickness (MFT), and nuclear-to-fiber (N/F) ratio. Seventy-four healthy young women (including 34 who used OCs and 40 who did not) underwent 12 weeks of submaximal strength training, after which Fmax was evaluated using a leg-press machine with a combined force and load cell, while Mtk was measured using real-time ultrasonography. Moreover, the NO ratio, MFT, and N/F ratio were evaluated using muscle needle biopsies.ResultsParticipants in the non-OC and OC groups experienced increases in Fmax (+ 23.30 ± 10.82 kg and + 28.02 ± 11.50 kg respectively, p = 0.073), Mtk (+ 0.48 ± 0.47 cm2 and + 0.50 ± 0.44 cm2 respectively, p = 0.888), Fmax/Mtk (+ 2.78 ± 1.93 kg/cm2 and + 3.32 ± 2.37 kg/cm2 respectively, p = 0.285), NO ratio (type 2 fibers: + 1.86 ± 6.49% and − 4.17 ± 9.48% respectively, p = 0.169), MFT (type 2 fibers: + 7.15 ± 7.50 µm and + 4.07 ± 9.30 µm respectively, p = 0.435), and N/F ratio (+ 0.61 ± 1.02 and + 0.15 ± 0.97 respectively, p = 0.866) after training. There were no significant differences between the non-OC and OC groups in any of these parameters (p > 0.05).ConclusionsThe effects of 12 weeks of strength training on Fmax, muscle thickness, muscle fiber size, and composition were similar in young women irrespective of their OC use.

Physical exercise is an effective measure to prevent sarcopenia. However, the effects of Nordic walking based on high-intensity interval training (HIIT NW) and conventional strength training (ST) on the parameters related to sarcopenia in postmenopausal women remain unclear. Therefore, this study aims to evaluate the effects of 12-week HIIT NW and ST on body composition and physical function performance in postmenopausal women. The participants were 71 women aged between 60 and 79 years old without sarcopenia. Participants were randomly assigned to the HIIT NW group (12-week Nordic walking training, 3 × /week), the ST group (12-week strength training, 3 × /week), and the control group. The body composition was determined by using Otupole InBody 720. Test the hand grip strength with a digital hand force gauge. The strength of the extensor and flexor muscles of the knee joint was measured using Biodex System 4 Pro™. This study also employed common methods for measuring functional performance and conducted two measurements of blood creatinine and creatine kinase. Compared with the control group, significant improvements were observed in parameters such as Time Up and Go (TUG) and knee joint flexor strength (KFS) in both the HIIT NW group and the ST group. In the ST group alone, significant enhancements were noted in parameters including walking speed (GS) and hand strength on the left side (HS-L). Following the intervention, the HIIT NW group exhibited a marked increase in limb lean mass, which led to a significant rise in the skeletal muscle index (SMI) (p < 0.001). However, the body fat mass (BFM) and body mass index (BMI) decreased significantly in the ST group (p < 0.001 and p = 0.005, respectively). No significant changes were observed in the control group. Both HIIT NW and ST interventions can effectively prevent sarcopenia in postmenopausal women. The former focuses on improving lower limb strength, while the latter focuses on improving upper limb strength. In the short term, the HIIT NW intervention model is more beneficial for postmenopausal women with normal weight, while the conventional ST intervention model is more conducive to the overweight population.

Nonsteroidal Anti-Inflammatory Drug or Glucosamine Reduced Pain and Improved Muscle Strength With Resistance Training in a Randomized Controlled Trial of Knee Osteoarthritis Patients

The purpose of this study was to compare the effects of 1 and 2 days per week of strength training on upper body strength, lower body strength, and motor performance ability in children. Twenty-one girls and 34 boys between the ages of 7.1 and 12.3 years volunteered to participate in this study. Participants strength trained either once per week (n = 22) or twice per week (n = 20) for 8 weeks at a community-based youth fitness center. Each training session consisted of a single set of 10–15 repetitions on 12 exercises using child-size weight machines. Thirteen children who did not strength train served as age-matched controls. One repetition maximum (1RM) strength on the chest press and leg press, handgrip strength, long jump, vertical jump, and flexibility were assessed at baseline and posttraining. Only participants who strength trained twice per week made significantly greater gains in 1RM chest press strength, compared to the control group (11.5 and 4.4% respectively, p < .05). Participants who trained once and twice per week made gains in 1RM leg press strength (14.2 and 24.7%, respectively) that were significantly greater than control group gains (2.4%). On average, participants who strength trained once per week achieved 67% of the 1RM strength gains. No significant differences between groups were observed on other outcome measures. These findings support the concept that muscular strength can be improved during the childhood years and favor a training frequency of twice per week for children participating in an introductory strength training program.

Neural adaptations to strength training have long been recognized, but knowledge of mechanisms remains incomplete. Using novel techniques and a design which limited experimental bias, this study examined if 4 wk of strength training alters voluntary activation and corticospinal transmission. Twenty-one subjects were randomized into strength training (n = 10; 7 females, 3 males; 23.5 ± 7.5 yr; mean ± SD) and control groups (n = 11; 2 females, 9 males; 23.0 ± 4.2 yr). Strength training involved 12 sessions of high-force isometric contractions of the elbow flexors. Before and after training, voluntary activation of the elbow flexors was assessed via transcranial magnetic stimulation. Also, for the first time, magnetic stimulation of corticospinal axons was used to examine spinal-level adaptations to training. The evoked responses, termed cervicomedullary motor-evoked potentials (CMEPs), were acquired in resting biceps brachii in three arm postures. Muscle adaptations were assessed via electrical stimulation of biceps. Compared with the control group, the strength training group exhibited greater increases in maximal strength (12.8% ± 6.8% vs 0.0% ± 2.7%; P < 0.001), biceps electromyographic activity (27.8% ± 25.9% vs -5.2% ± 16.8%; P = 0.002), and voluntary activation (4.7% ± 3.9% raw change vs -0.1% ± 5.2%; P = 0.034). Biceps CMEPs in all arm postures were unchanged after training. Biceps twitch characteristics were also unchanged. Four weeks of isometric strength training of the elbow flexors increased muscle strength and voluntary activation, without a change in the muscle. The improvement in activation suggests that voluntary output from the cortex was better able to recruit motoneurons and/or increase their firing rates. The lack of change in CMEPs indicates that neither corticospinal transmission nor motoneuron excitability was affected by training.

Purpose: We aimed to determine the effects of 12weeks of soy milk consumption combined with resistance training (RT) on body composition, physical performance, and skeletal muscle regulatory markers in older men. Methods: In this randomized clinical trial study, 60 healthy elderly men (age = 65.63 ± 3.16years) were randomly assigned to four groups: resistance training (RT; n = 15), soy milk consumption (SMC; n = 15), resistance training + soy milk (RSM; n = 15), and control (CON; n = 15) groups. The study was double-blind for the soy milk/placebo. Participants in RT and RSM groups performed resistance training (3 times/week) for 12weeks. Participants in the SMC and RSM groups consumed 240mL of soy milk daily. Body composition [body mass (BM), body fat percent (BFP), waist-hip ratio (WHR), and fat mass (FM)], physical performance [upper body strength (UBS), lower body strength (LBS), VO2max, upper anaerobic power, lower anaerobic power, and handgrip strength], and serum markers [follistatin, myostatin, myostatin-follistatin ratio (MFR), and growth and differentiation factor 11 (GDF11)] were evaluated before and after interventions. Results: All 3 interventions significantly (p < 0.05) increased serum follistatin concentrations (RT = 1.7%, SMC = 2.9%, RSM = 7.8%) and decreased serum myostatin (RT = -1.3% SMC = -5.4%, RSM = -0.5%) and GDF11 concentrations (RT = -1.4%, SMC = -1.4%, RSM = -9.0%), and MFR (RT = -2.6%, SMC = -3.2%, RSM = -12%). In addition, we observed significant reduction in all 3 intervention groups in BFP (RT = -3.6%, SMC = -1.4%, RSM = -6.0%), WHR (RT = -2.2%, SMC = -2.1%, RSM = -4.3%), and FM (RT = -9.6%, SMC = -3.8%, RSM = -11.0%). Moreover, results found significant increase only in RT and RSM groups for muscle mass (RT = 3.8% and RSM = 11.8%), UBS (RT = 10.9% and RSM = 21.8%), LBS (RT = 4.3% and RSM = 7.8%), upper anaerobic power (RT = 7.8% and RSM = 10.3%), and lower anaerobic power (RT = 4.6% and RSM = 8.9%). Handgrip strength were significantly increased in all 3 intervention groups (RT = 7.0%, SMC = 6.9%, RSM = 43.0%). VO2max significantly increased only in RSM (1.7%) after 12weeks of intervention. Additionally, significant differences were observed between the changes for all variables in the RSM group compared to RT, SMC, and CON groups (p < 0.05). Conclusions: There were synergistic effects of soy milk and RT for skeletal muscle regulatory markers, body composition, and physical performance. Results of the present study support the importance of soy milk in conjunction with RT for older men.

Background. The irisin and betatrophin hormones are involved in insulin resistance. Considering the muscle weakness of elderly diabetics, this study aimed to investigate the effect of 21 weeks of strength training on betatrophin and irisin serum levels in type 2 diabetic elderly men. Methods. This semi-experimental study was conducted on type 2 diabetic men with an average age of 70.85±2.90 years. The strength training protocol was performed twice a week for 21 weeks. The exercises consisted of three stages: 1- muscle endurance, 2- muscle hypertrophy, and 3- maximum strength training. Fasting blood glucose levels and serum levels of insulin, betatrophin, and irisin were measured in two phases before and after the exercises. Results. The serum levels of insulin, irisin, and betatrophin in the diabetes control group were lower than in the healthy group (P&lt;0.05) and 21 weeks of strength training increased the serum levels of insulin, irisin, and betatrophin, and decreased body weight and fasting blood glucose levels in elderly diabetic men compared to the control group (P&lt;0.05). Conclusion. Strength training improved metabolic disorders in diabetics and increased secretion of irisin and betatrophin following exercise which indicated that exercise may have a protective mechanism in diabetes. Practical Implications. Stationary movements by performing strength activities, through the development of skeletal muscles of diabetics, improve insulin sensitivity and harvest more glucose in the body. In addition, these exercises can be a protective mechanism to prevent or delay the complications of type 2 diabetes by increasing irisin and betatrophin levels.

A 10-week strength training program: Effect on the motor performance of an unimpaired upper extremity

Sarcopenia in patients with cancer makes patients physically weak and adversely affects their compliance with treatment. In this study, we investigated the relationship between sarcopenia in patients with cancer and circulating irisin and tumor necrosis factor-alpha (TNF-α) levels. A total of 141 patients with different types of newly diagnosed cancer were divided into two groups, sarcopenia (n = 72) and non-sarcopenia (n = 69) groups. The body compositions of the patients were measured using bioelectrical impedance (BIA) and muscle strength using hand grip strength (HGS) tests. Serum irisin and TNF-α levels were measured using an enzyme-linked immunosorbent assay. In our study, serum irisin levels were found to be significantly lower (p < 0.01) and TNF-α levels were found to be significantly higher (p = 0.014) in the sarcopenia group. Skeletal muscle index (SMI) and HGS values and serum irisin levels were positively correlated [(r: 0.451, p < 0.001), (r: 0.469, p < 0.001)], and SMI and HGS values and serum TNF-α levels were negatively correlated [(r: -0.181, p = 0.032) and (r: -0.143, p = 0.090), respectively]. In addition, multiple linear regression analysis showed that serum irisin and TNF-α levels were independent predictors of sarcopenia. Serum irisin levels were found to be significantly lower in patients with cancer with sarcopenia, and TNF-α levels were found to be significantly higher. These two markers can be used as potential biomarkers for the diagnosis of sarcopenia in patients with cancer. The efficacy and possible mechanisms of action of irisin and TNF-α in the diagnosis of sarcopenia should be investigated with larger patient groups.