Gul Tiryaki-Sonmez

Influence of Resistance Training Frequency on Muscular Adaptations in Well-trained Men

Abstract Schoenfeld, BJ, Ratamess, NA, Peterson, MD, Contreras, B, and Tiryaki-Sonmez, G. Influence of resistance training frequency on muscular adaptations in well-trained men. J Strength Cond Res 29(7): 1821–1829, 2015—The purpose of this study was to investigate the effects of training muscle groups 1 day per week using a split-body routine (SPLIT) vs. 3 days per week using a total-body routine (TOTAL) on muscular adaptations in well-trained men. Subjects were 20 male volunteers (height = 1.76 ± 0.05 m; body mass = 78.0 ± 10.7 kg; age = 23.5 ± 2.9 years) recruited from a university population. Participants were pair matched according to baseline strength and then randomly assigned to 1 of the 2 experimental groups: a SPLIT, where multiple exercises were performed for a specific muscle group in a session with 2–3 muscle groups trained per session (n = 10) or a TOTAL, where 1 exercise was performed per muscle group in a session with all muscle groups trained in each session (n = 10). Subjects were tested pre- and poststudy for 1 repetition maximum strength in the bench press and squat, and muscle thickness (MT) of forearm flexors, forearm extensors, and vastus lateralis. Results showed significantly greater increases in forearm flexor MT for TOTAL compared with SPLIT. No significant differences were noted in maximal strength measures. The findings suggest a potentially superior hypertrophic benefit to higher weekly resistance training frequencies.

Effect of Exercise on Appetite-Regulating Hormones in Overweight Women

Over the past decade, our knowledge of how homeostatic systems regulate food intake and body weight has increased with the discovery of circulating peptides such as leptin, acyl ghrelin, des-acyl ghrelin and obestatin. These hormones regulate the appetite and food intake by sending signals to the brain regarding the bodys nutritional status. The purpose of this study was to investigate the response of appetite-regulating hormones to exercise. Nine overweight women undertook two 2 h trials in a randomized crossover design. In the exercise trial, subjects ran for 60 min at 50% of maximal oxygen uptake followed by a 60 min rest period. In the control trial, subjects rested for 2 h. Obestatin, acyl ghrelin, des-acyl ghrelin and leptin concentrations were measured at baseline and at 20, 40, 60, 90 and 120 min after baseline. A two-way ANOVA revealed a significant (P < 0.05) interaction effect for leptin and acyl ghrelin. However, changes in obestatin and des-acyl ghrelin concentration were statistically insignificant (P > 0.05). The data indicated that although acute treadmill exercise resulted in a significant change in acyl ghrelin and leptin levels, it had no effect on plasma obestatin and des-acyl ghrelin levels.

REGIONAL DIFFERENCES IN MUSCLE ACTIVATION DURING HAMSTRINGS EXERCISE

Abstract Schoenfeld, BJ, Contreras, B, Tiryaki-Sonmez, G, Wilson, JM, Kolber, MJ, and Peterson, MD. Regional differences in muscle activation during hamstrings exercise. J Strength Cond Res 29(1): 159–164, 2015—It is believed that regional activation within a muscle may lead to greater site-specific muscular adaptations in the activated portion of the muscle. Because the hamstrings are a biarticular muscle, it can be theorized that single-joint exercises where movement originates at the hip vs. the knee will result in differential activation of the muscle complex. The purpose of the present study was to assess electromyographic activity in the proximal and distal aspects of the medial and lateral hamstrings during performance of the stiff-legged deadlift (SLDL), a hip-dominant exercise, and the lying leg curl (LLC), a knee-dominant exercise. Ten young, resistance-trained men were recruited from a university population to participate in the study. Employing a within-subject design, participants performed the SLDL and LLC to muscular failure using a load equating to their 8 repetition maximum for each exercise. The order of performance of exercises was counterbalanced between participants so that approximately half of the subjects performed SLDL first and the other half performed LLC first. Surface electromyography was used to record mean normalized muscle activity of the upper lateral hamstrings, lower lateral hamstrings, upper medial hamstrings, and lower medial hamstrings. Results showed that the LLC elicited significantly greater normalized mean activation of the lower lateral and lower medial hamstrings compared with the SLDL (p ⩽ 0.05). These findings support the notion that the hamstrings can be regionally targeted through exercise selection. Further investigations are required to determine whether differences in activation lead to greater muscular adaptations in the muscle complex.

An electromyographic comparison of a modified version of the plank with a long lever and posterior tilt versus the traditional plank exercise

The purpose of the study was to compare core muscle activation of the tradition prone plank with a modified version performed with a long-lever and posterior-tilt using surface electromyography. To further determine if a specific component of this modified plank was more effective than the other in enhancing muscle activity, the plank with a long lever and the plank with a posterior pelvic tilt were studied individually. Nineteen participants performed all four variations of the plank for 30 seconds in a randomized order with 5-minute rest between exercise bouts. Compared to the traditional prone plank, the long-lever posterior-tilt plank displayed a significantly increased activation of the upper rectus abdominis (p < 0.001), lower abdominal stabilizers (p < 0.001), and external oblique (p < 0.001). The long-lever plank showed significantly greater activity compared to the traditional plank in the upper rectus abdominis (p = 0.015) and lower abdominal stabilizers (p < 0.001), while the posterior tilt plank elicited greater activity in the external oblique (p = 0.028). In conclusion, the long-lever posterior-tilt plank significantly increases muscle activation compared to the traditional prone plank. The long-lever component tends to contribute more to these differences than the posterior-tilt component.

Upper body muscle activation during low-versus high-load resistance exercise in the bench press

OBJECTIVE: The purpose of this study was to compare activation of the upper body musculature during the barbell bench press at varying training intensities. METHODS: Twelve young, resistance-trained men performed sets of the bench press to momentary muscular failure with two different loads: a high-load (HIGH) set at 80% of 1RM and a low-load (LOW) set at 50% 1RM. Exercise order was counterbalanced so that half the subjects performed the LOW condition first and the other half performed the HIGH first. Surface electromyography (EMG) was used to assess mean, peak, and iEMG muscle activation of the anterior deltoid, triceps brachii, and sternal and clavicular heads of the pectoralis major. RESULTS: The main effects for trials were significant for mean EMG ( p< 0.001) and iEMG matched ( p< 0.001) favoring HIGH and iEMG total favoring LOW (p = 0.001) across all muscle groups in both conditions with varying effect sizes. All other main effects and interactions were not statistically significant. CONCLUSION: Despite similaritiesin peak EMG amplitude, the greater results for mean and iEMG matched in HIGH suggests that heavier loads may produce greater muscle activation.

Omega-3 fatty acids and exercise: a review of their combined effects on body composition and physical performance

Omega-3 fatty acids and exercise: a review of their combined effects on body composition and physical performance Omega-3 (n-3) fatty acids, and the long-chain n-3 derivatives eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in particular, have been extensively researched for their nutritive effects. Among their many purported benefits, n-3 acids have been implicated as positive mediators of cardiovascular health and body composition. It has therefore been speculated that supplementation may enhance the beneficial effects of physical activity, potentiating greater reductions in body fat and improvements in exercise performance. This paper has three objectives: first, to assess the theoretical basis for a synergistic ef-fect when n-3 supplementation is combined with exercise; second, to review the literature as to specific findings on the subject and third, to make relevant conclusions and recommendations for future research.

Comparison of amplitude-mode ultrasound versus air displacement plethysmography for assessing body composition changes following participation in a structured weight-loss programme in women

The purpose of this study was to compare body composition changes as measured by A‐mode ultrasound (US) versus a criterion densitometry‐based measure, air displacement plethysmography (ADP), over a 4‐week weight‐loss protocol in healthy, non‐obese young women. Twenty healthy, young female volunteers were provided with customized dietary plans for the length of the study intended to facilitate a 500 calorie‐a‐day deficit. Subjects also performed 3 h a week of supervised aerobic exercise. Per cent fat mass and lean body mass were obtained via ADP and US both pre‐ and postintervention. Pretesting, post‐testing and delta data for %fat resulted in no significant differences in mean values along with a slope of the regression line no different than one and a y‐intercept no different than zero (P<0·05). Similar to %fat values, pretesting, post‐testing and delta data for fat‐free mass resulted in no significant differences in mean values along with a slope of the regression line no different than one and a y‐intercept no different than zero (P<0·05) with the exception of the delta for slope (0·39, P = 0·04). The current findings indicate that US can provide a similar degree of accuracy for tracking group‐based fat loss in women compared to ADP. Given the low‐cost relative to DXA and ADP, researchers and practitioners therefore can consider US as a viable option for monitoring group‐based changes in body fat over time.

Body Mass Disorders in Healthy Short Children and in Children with Growth Hormone Deficiency

The aim of the study was to determine the degree of adiposity and the incidence of body mass disorders, including abdominal obesity, in healthy short children and children with growth hormone deficiency. The study included 134 short children (height < 10th percentile) aged 7-15. In this cohort there were 63 (31 boys and 32 girls) children without diagnosed hormonal disorders and 71 patients (35 boys and 36 girls) with growth hormone deficiency. Basic somatic features were assessed and the study participants were categorized according to the percentage of body fat (%FAT), body mass index (BMI), and waist-to-height ratio (WHtR). We found that there were no significant differences in %FAT and the incidence of body weight disorders depending on gender or diagnosis. %FAT deficit was observed in 12-21% of the participants and underweight in almost every fourth child. Overweight involved 3-14% of the participants and obesity was diagnosed in isolated cases (0-3%); both were considerably lower compared to the estimates based on %FAT. Using the cut-off points of WHtR, abdominal adiposity was observed in 3-15% of the participants. In conclusion, quite a large number of short children (between 25 and 50%) are characterized by abnormal body fat or body mass index values. The results indicate a limited usefulness of BMI in evaluating the incidence of overweight and obesity in children characterized by a height deficit.

Obesity, food intake and exercise: Relationship with ghrelin

Summary Obesity, a disorder of body composition, is defined by a relative or absolute excess of body fat. In general adult population, obesity has been associated with a diverse array of adverse health outcomes, including major causes of death such as cancer, diabetes, cardiovascular disease, as well as functional impairment from problems such as osteoarthritis and sleep apnea. Ghrelin is a newly discovered peptide hormone which plays an important role in obesity. It is a powerful, endogenous orexigenic peptide and has a crucial function in appetite regulation, as well as short – and long-term energy homeostasis. In the presence of increased obesity, decreased physical activity, and high food consumption, the relationship between exercise, appetite, food intake and ghrelin levels has important implications. In this review, we discuss the effect of acute and chronic exercise performance on appetite, food intake and ghrelin and their relationships.

Overcoming psychosocial barriers to maternal exercise: intervention strategies to improve participation and adherence

Overcoming psychosocial barriers to maternal exercise: intervention strategies to improve participation and adherence Poor adherence to physical activity programmes during pregnancy is a serious national issue, one that has detrimental effects on a large percentage of the population. Not only does a lack of activity result in a decrease in quality of life for women during term, but the effects can carry over well after pregnancy, potentially leading to increased morbidity and mortality. Whats more, reduced prenatal activity can cause adverse effects on the foetus, with impairments seen in physical health as well as cognition. Accordingly, the purpose of this paper is twofold: first, to examine the socio-demographic data and psychosocial influences that modify exercise behaviours in pregnant women and, second, to make recommendations as to effective intervention strategies that can be adopted by health and fitness professionals to help improve maternal exercise participation and adherence.