training volume in muscle hypertrophy and strength in trained men—less is more? Int J Sports Physiol Perform . 2020;15(2):268–277. doi: 10.1123/ijspp.2018-0914
The aim of this investigation was to assess the influence of an 8-month physical training period on left ventricular voltages identified by resting ECG in relation to changes in left ventricle mass in adolescent athletes.
The study encompassed 28 adolescents aged 13 years (14 boys and 14 girls) from a sports secondary school. Clinical assessment was performed on all athletes before and after 8 months of physical training.
Sokolov-Lyon voltage index, Cornell voltage index, and maximum spatial QRS vector magnitude demonstrated statistically significant decline during the study period. The specific potential of the myocardium also significantly decreased during 8 months of training. The Sokolov-Lyon voltage criterion for left ventricular hypertrophy was fulfilled in 9 athletes (32.1%) at the beginning of the observation and only in 3 athletes (10.7%) at the end of the study. On the other hand, mean left ventricular mass and mean left ventricular mass index significantly increased after long-term training. No statistically significant correlations were identified between relative changes in left ventricular mass and QRS voltages.
An early period of intensive physical training in young athletes is associated with a decrease in QRS amplitude and a relative voltage deficit over the left ventricle.
Paul D. Loprinzi and Manish Kohli
Independent of previously recognized clinical factors influencing prostate-specific antigen (PSA) levels (eg, age and race-ethnicity), sedentary behavior has recently been reported to be associated with higher PSA measurements. The extent of interaction of putative clinical factors with sedentary behavior and their impact on PSA levels is unknown. We examined the interaction of previously known PSA influencing demographic patient characteristics with patient sedentary behavior on PSA levels.
Data from the 2003–2006 National Health and Nutrition Examination Survey were used. Sedentary behavior was objectively measured using an accelerometer in 1690 participants who were included in the analytic sample. Multivariate linear regression analysis across potential clinical and biological modifiers of PSA levels were used to examine the association between sedentary behavior and PSA levels.
After controlling for covariates, a positive association between sedentary behavior and PSA was detected among distinctive patient groups, including non-Hispanic whites, overweight/obese subjects, hypertensive participants, and participants with evidence of diabetes and those reported to have benign prostate hypertrophy.
These results suggest that patients with distinct clinical characteristics engaging in sedentary lifestyles are likely to have higher PSA levels.
Kristen L. MacKenzie-Shalders, Neil A. King, Nuala M. Byrne and Gary J. Slater
Increasing the frequency of protein consumption is recommended to stimulate muscle hypertrophy with resistance exercise. This study manipulated dietary protein distribution to assess the effect on gains in lean mass during a rugby preseason. Twenty-four developing elite rugby athletes (age 20.1 ± 1.4 years, mass 101.6 ± 12.0 kg; M ± SD) were instructed to consume high biological value (HBV) protein at their main meals and immediately after resistance exercise while limiting protein intake between meals. To manipulate protein intake frequency, the athletes consumed 3 HBV liquid protein supplements (22 g protein) either with main meals (bolus condition) or between meals (frequent condition) for 6 weeks in a 2 × 2 crossover design. Dietary intake and change in lean mass values were compared between conditions by analysis of covariance and correlational analysis. The dietary manipulation successfully altered the protein distribution score (average number of eating occasions containing > 20 g of protein) to 4.0 ± 0.8 and 5.9 ± 0.7 (p < .01) for the bolus and frequent conditions, respectively. There was no difference in gains in lean mass between the bolus (1.4 ± 1.5 kg) and frequent (1.5 ± 1.4 kg) conditions (p = .91). There was no clear effect of increasing protein distribution from approximately 4–6 eating occasions on changes in lean mass during a rugby preseason. However, other dietary factors may have augmented adaptation.
Yasuo Kawakami, Yoshiho Ichinose, Keitaro Kubo, Masamitsu Ito, Morihiro Imai and Tetsuo Fukunaga
This paper reviews three of our recent studies on human muscle architecture in vivo. 1. Hypertrophic changes: From B-mode ultrasonograms, pennation angles and thickness of triceps brachii were determined for normal subjects and highly-trained bodybuilders. There was a significant correlation between muscle thickness and pennation angles. It was confirmed that hypertrophy was accompanied by an increase in pennation angles. 2. Variation of fascicle architecture: Fascicle lengths and pennation angles were obtained from different positions in the gastrocnemius muscle while the subjects relaxed and performed isometric plantar flexion. The fascicle length was uniform throughout the muscle and shortened by contraction (30-34% at 50% of the maximal force). On the other hand, pennation angles differed among positions and increased by contraction. The muscle thickness did not change by contraction. Pen-nation angles were significantly correlated with muscle thickness within muscle. 3. Joint position-fascicle length relationships: Ultrasonic images of the gastrocnemius and soleus muscles were obtained while the subject performed maximal isometric plantarflexion at various joint positions, from which fascicle lengths and angles were determined. The length-force relationship of each muscle was estimated. It was suggested that human muscle architecture has an ability to make substantial changes to adapt to environmental conditions.
Warren B. Young
The purposes of this review are to identify the factors that contribute to the transference of strength and power training to sports performance and to provide resistance-training guidelines. Using sprinting performance as an example, exercises involving bilateral contractions of the leg muscles resulting in vertical movement, such as squats and jump squats, have minimal transfer to performance. However, plyometric training, including unilateral exercises and horizontal movement of the whole body, elicits significant increases in sprint acceleration performance, thus highlighting the importance of movement pattern and contraction velocity specificity. Relatively large gains in power output in nonspecific movements (intramuscular coordination) can be accompanied by small changes in sprint performance. Research on neural adaptations to resistance training indicates that intermuscular coordination is an important component in achieving transfer to sports skills. Although the specificity of resistance training is important, general strength training is potentially useful for the purposes of increasing body mass, decreasing the risk of soft-tissue injuries, and developing core stability. Hypertrophy and general power exercises can enhance sports performance, but optimal transfer from training also requires a specific exercise program.
Bret Contreras, Andrew D. Vigotsky, Brad J. Schoenfeld, Chris Beardsley and John Cronin
The back squat and barbell hip thrust are both popular exercises used to target the lower body musculature; however, these exercises have yet to be compared. Therefore, the purpose of this study was to compare the surface electromyographic (EMG) activity of the upper and lower gluteus maximus, biceps femoris, and vastus lateralis between the back squat and barbell hip thrust. Thirteen trained women (n = 13; age = 28.9 years; height = 164 cm; mass = 58.2 kg) performed estimated 10-repetition maximums (RM) in the back squat and barbell hip thrust. The barbell hip thrust elicited significantly greater mean (69.5% vs 29.4%) and peak (172% vs 84.9%) upper gluteus maximus, mean (86.8% vs 45.4%) and peak (216% vs 130%) lower gluteus maximus, and mean (40.8% vs 14.9%) and peak (86.9% vs 37.5%) biceps femoris EMG activity than the back squat. There were no significant differences in mean (99.5% vs 110%) or peak (216% vs 244%) vastus lateralis EMG activity. The barbell hip thrust activates the gluteus maximus and biceps femoris to a greater degree than the back squat when using estimated 10RM loads. Longitudinal training studies are needed to determine if this enhanced activation correlates with increased strength, hypertrophy, and performance.
Kevin D. Tipton
Adaptations to exercise training are determined by the response of metabolic and molecular mechanisms that determine changes in proteins. The type, intensity, and duration of exercise, as well as nutrition, determine these responses. The importance of protein, in the form of intact proteins, hydrolysates, or free amino acids, for exercise adaptations is widely recognized. Exercise along with protein intake results in accumulation of proteins that influence training adaptations. The total amount of protein necessary to optimize adaptations is less important than the type of protein, timing of protein intake, and the other nutrients ingested concurrently with the protein. Acute metabolic studies offer an important tool to study the responses of protein balance to various exercise and nutritional interventions. Recent studies suggest that ingestion of free amino acids plus carbohydrates before exercise results in a superior anabolic response to exercise than if ingested after exercise. However, the difference between pre- and post exercise ingestion of intact proteins is not apparent. Thus, the anabolic response to exercise plus protein ingestion seems to be determined by the interaction of timing of nutrient intake in relation to exercise and the nutrients ingested. More research is necessary to delineate the optimal combination of nutrients and timing for various types of training adaptations. Protein and amino acid intake have long been deemed important for athletes and exercising individuals. Olympic athletes, from the legendary Milo to many in the 1936 Berlin games, reportedly consumed large amounts of protein. Modern athletes may consume slightly less than these historical figures, yet protein is deemed extremely important by most. Protein is important as a source of amino acids for recovery from exercise and repair of damaged tissues, as well as for adaptations to exercise training, such as muscle hypertrophy and mitochondrial biogenesis.
Sunhyo Jeong and Michung Yoon
Ovariectomy leads to weight gain primarily in the form of adipose tissue in rodents. The authors investigated whether swimming improves ovariectomy-induced obesity through activation of peroxisome proliferatoractivated receptor α (PPARα) in the skeletal muscle of female ovariectomized (OVX) mice, an animal model of postmenopausal women. Female mice were randomly divided into 3 groups (n = 8/group): a sedentary sham-operated group, a sedentary OVX group, and a swim-trained OVX group. After mice were subjected to swim training or kept sedentary for 6 wk, the authors studied the effects of swimming on not only bodyweight gain, white adipose tissue (WAT) mass, adipocyte size, and skeletal-muscle lipid accumulation but also the expression of skeletal-muscle PPARα target genes. Sedentary OVX mice had significantly higher body weight and WAT than sedentary sham mice. However, swim training reduced body-weight gain, WAT mass, and adipocyte size of OVX mice. Swim-trained OVX mice had significantly lower levels of serum triglycerides and total cholesterol than sedentary OVX mice. Lipid accumulation in skeletal muscle was also markedly decreased by swimming. Concomitantly, swim training significantly increased mRNA levels of skeletal-muscle PPARα and its target enzymes, as well as uncoupling protein 3 (UCP3) responsible for fattyacid oxidation. These results suggest that swimming can effectively prevent weight gain, adiposity, adipocyte hypertrophy, and lipid disorders caused by ovariectomy, in part through the activation of PPARα and UCP3, in the skeletal muscle of female mice and may contribute to the alleviation of metabolic syndrome, including obesity, hyperlipidemia, and Type 2 diabetes in postmenopausal women.
In the article, Sugihara Junior, P., Ribeiro, A. S., Nabuco, H.G., Fernandes, R. R., Tomeleri, C. M., Cunha, P. M., Venturini, D., Barbosa, D. S., Schoenfeld, B. J., & Cyrino, E. S. (2018). Effects of Whey Protein Supplementation Associated With Resistance Training on Muscular Strength, Hypertrophy