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Concept: Physical exercise



Today¿s cell phones increase opportunities for activities traditionally defined as sedentary behaviors (e.g., surfing the internet, playing video games). People who participate in large amounts of sedentary behaviors, relative to those who do not, tend to be less physically active, less physically fit, and at greater risk for health problems. However, cell phone use does not have to be a sedentary behavior as these devices are portable. It can occur while standing or during mild-to-moderate intensity physical activity. Thus, the relationship between cell phone use, physical and sedentary activity, and physical fitness is unclear. The purpose of this study was to investigate these relationships among a sample of healthy college students.

Concepts: Obesity, Physical exercise, Exercise, Mobile phone, Internet, Cardiorespiratory fitness, Physical fitness, Cellular network


Chronic supplementation with creatine monohydrate has been shown to promote increases in total intramuscular creatine, phosphocreatine, skeletal muscle mass, lean body mass and muscle fiber size. Furthermore, there is robust evidence that muscular strength and power will also increase after supplementing with creatine. However, it is not known if the timing of creatine supplementation will affect the adaptive response to exercise. Thus, the purpose of this investigation was to determine the difference between pre versus post exercise supplementation of creatine on measures of body composition and strength.

Concepts: Muscle, Physical exercise, Cardiac muscle, Glycogen, Myosin, Muscular system, Acetylcholine, Exercise physiology


The purpose of this review was to determine whether past research provides conclusive evidence about the effects of type and timing of ingestion of specific sources of protein by those engaged in resistance weight training. Two essential, nutrition-related, tenets need to be followed by weightlifters to maximize muscle hypertrophy: the consumption of 1.2-2.0 g -1 of body weight, and >=44-50 of body weight. Researchers have tested the effects of timing of protein supplement ingestion on various physical changes in weightlifters. In general, protein supplementation pre- and post-workout increases physical performance, training session recovery, lean body mass, muscle hypertrophy, and strength. Specific gains, differ however based on protein type and amounts. Studies on timing of consumption of milk have indicated that fat-free milk post-workout was effective in promoting increases in lean body mass, strength, muscle hypertrophy and decreases in body fat. The leucine content of a protein source has an impact on protein synthesis, and affects muscle hypertrophy. Consumption of 3–4 g of leucine is needed to promote maximum protein synthesis. An ideal supplement following resistance exercise should contain whey protein that provides at least 3 g of leucine per serving. A combination of a fast-acting carbohydrate source such as maltodextrin or glucose should be consumed with the protein source, as leucine cannot modulate protein synthesis as effectively without the presence of insulin. Such a supplement post-workout would be most effective in increasing muscle protein synthesis, resulting in greater muscle hypertrophy and strength. In contrast, the consumption of essential amino acids and dextrose appears to be most effective at evoking protein synthesis prior to rather than following resistance exercise. To further enhance muscle hypertrophy and strength, a resistance weight- training program of at least 10–12 weeks with compound movements for both upper and lower body exercises should be followed.

Concepts: Protein, Amino acid, Glucose, Muscle, Physical exercise, Strength training, Exercise physiology, Bodybuilding


Protein timing is a popular dietary strategy designed to optimize the adaptive response to exercise. The strategy involves consuming protein in and around a training session in an effort to facilitate muscular repair and remodeling, and thereby enhance post-exercise strength- and hypertrophy-related adaptations. Despite the apparent biological plausibility of the strategy, however, the effectiveness of protein timing in chronic training studies has been decidedly mixed. The purpose of this paper therefore was to conduct a multi-level meta-regression of randomized controlled trials to determine whether protein timing is a viable strategy for enhancing post-exercise muscular adaptations. The strength analysis comprised 478 subjects and 96 ESs, nested within 41 treatment or control groups and 20 studies. The hypertrophy analysis comprised 525 subjects and 132 ESs, nested with 47 treatment or control groups and 23 studies. A simple pooled analysis of protein timing without controlling for covariates showed a small to moderate effect on muscle hypertrophy with no significant effect found on muscle strength. In the full meta-regression model controlling for all covariates, however, no significant differences were found between treatment and control for strength or hypertrophy. The reduced model was not significantly different from the full model for either strength or hypertrophy. With respect to hypertrophy, total protein intake was the strongest predictor of ES magnitude. These results refute the commonly held belief that the timing of protein intake in and around a training session is critical to muscular adaptations and indicate that consuming adequate protein in combination with resistance exercise is the key factor for maximizing muscle protein accretion.

Concepts: Metabolism, Energy, Muscle, Physical exercise, Actin, Tissues, Muscular system, Exercise physiology


Creatine is one of the most popular and widely researched natural supplements. The majority of studies have focused on the effects of creatine monohydrate on performance and health; however, many other forms of creatine exist and are commercially available in the sports nutrition/supplement market. Regardless of the form, supplementation with creatine has regularly shown to increase strength, fat free mass, and muscle morphology with concurrent heavy resistance training more than resistance training alone. Creatine may be of benefit in other modes of exercise such as high-intensity sprints or endurance training. However, it appears that the effects of creatine diminish as the length of time spent exercising increases. Even though not all individuals respond similarly to creatine supplementation, it is generally accepted that its supplementation increases creatine storage and promotes a faster regeneration of adenosine triphosphate between high intensity exercises. These improved outcomes will increase performance and promote greater training adaptations. More recent research suggests that creatine supplementation in amounts of 0.1 g/kg of body weight combined with resistance training improves training adaptations at a cellular and sub-cellular level. Finally, although presently ingesting creatine as an oral supplement is considered safe and ethical, the perception of safety cannot be guaranteed, especially when administered for long period of time to different populations (athletes, sedentary, patient, active, young or elderly).

Concepts: Time, Adenosine triphosphate, Obesity, Physical exercise, Exercise, Strength training, Creatine, Creatine supplements


Moderate-intensity exercise has attracted considerable attention because of its safety and many health benefits. Tai Chi, a form of mind-body exercise that originated in ancient China, has been gaining popularity. Practicing Tai Chi may improve overall health and well-being; however, to our knowledge, no study has evaluated its relationship with mortality. We assessed the associations of regular exercise and specifically participation in Tai Chi, walking, and jogging with total and cause-specific mortality among 61,477 Chinese men in the Shanghai Men’s Health Study (2002-2009). Information on exercise habits was obtained at baseline using a validated physical activity questionnaire. Deaths were ascertained through biennial home visits and linkage with a vital statistics registry. During a mean follow-up of 5.48 years, 2,421 deaths were identified. After adjustment for potential confounders, men who exercised regularly had a hazard ratio for total mortality of 0.80 (95% confidence interval: 0.74, 0.87) compared with men who did not exercise. The corresponding hazard ratios were 0.80 (95% confidence interval: 0.72, 0.89) for practicing Tai Chi, 0.77 (95% confidence interval: 0.69, 0.86) for walking, and 0.73 (95% confidence interval: 0.59, 0.90) for jogging. Similar inverse associations were also found for cancer and cardiovascular mortality. The present study provides the first evidence that, like walking and jogging, practicing Tai Chi is associated with reduced mortality.

Concepts: Statistics, Obesity, Cardiovascular disease, Physical exercise, Exercise, Interval finite element, Normal distribution, Physical fitness


BACKGROUND: Numerous natural products are marketed and sold claiming to decrease body weight and fat, but few undergo finished product-specific research demonstrating their safety and efficacy. OBJECTIVE: To determine the safety and efficacy of a multi-ingredient supplement containing primarily raspberry ketone, caffeine, capsaicin, garlic, ginger and Citrus aurantium (Prograde MetabolismTM [METABO]) as an adjunct to an eight-week weight loss program. METHODS: Using a randomized, placebo-controlled, double-blind design, 70 obese but otherwise healthy subjects were randomly assigned to METABO or a placebo and underwent 8 weeks of daily supplementation, a calorie restricted diet, and exercise training. Subjects were tested for changes in body composition, serum adipocytokines (adiponectin, resistin, leptin, TNF-alpha, IL-6) and markers of health including heart rate and blood pressure. RESULTS: Of the 45 subjects who completed the study, significant differences were observed in: body weight (METABO -2.0% vs. placebo -0.5%, P < 0.01), fat mass (METABO -7.8 vs. placebo -2.8%, P < 0.001), lean mass (METABO +3.4% vs. placebo +0.8%, P < 0.03), waist girth (METABO -2.0% vs. placebo -0.2%, P < 0.0007), hip girth (METABO -1.7% vs. placebo -0.4%, P < 0.003), and energy levels per anchored visual analogue scale (VAS) (METABO +29.3% vs. placebo +5.1%, P < 0.04). During the first 4 weeks, effects/trends for maintaining elevated serum leptin (P < 0.03) and decreased serum resistin (P < 0.08) in the METABO group vs. placebo were also observed. No changes in systemic hemodynamics, clinical blood chemistries, adverse events, or dietary intake were noted between groups. CONCLUSIONS: METABO administration is a safe and effective adjunct to an eight-week diet and exercise weight loss program by augmenting improvements in body composition, waist and hip girth. Adherence to the eight-week weight loss program also led to beneficial changes in body fat in placebo. Ongoing studies to confirm these results and clarify the mechanisms (i.e., biochemical and neuroendocrine mediators) by which METABO exerts the observed salutary effects are being conducted.

Concepts: Nutrition, Obesity, Physical exercise, Mass, Adipose tissue, Weight loss, Dieting, Leptin


BACKGROUND: The benefits of exercise are well established but one major barrier for many is time. It has been proposed that short period resistance training (RT) could play a role in weight control by increasing resting energy expenditure (REE) but the effects of different kinds of RT has not been widely reported. METHODS: We tested the acute effects of high-intensity interval resistance training (HIRT) vs. traditional resistance training (TT) on REE and respiratory ratio (RR) at 22 hours post-exercise. In two separate sessions, seventeen trained males carried out HIRT and TT protocols. The HIRT technique consists of: 6 repetitions, 20 seconds rest, 2/3 repetitions, 20 secs rest, 2/3 repetitions with 2[prime]30[prime][prime] rest between sets, three exercises for a total of 7 sets. TT consisted of eight exercises of 4 sets of 8–12 repetitions with one/two minutes rest with a total amount of 32 sets. We measured basal REE and RR (TT0 and HIRT0) and 22 hours after the training session (TT22 and HIRT22). RESULTS: HIRT showed a greater significant increase (p < 0.001) in REE at 22 hours compared to TT (HIRT22 2362 +/- 118 Kcal/d vs TT22 1999 +/- 88 Kcal/d). RR at HIRT22 was significantly lower (0.798 +/- 0.010) compared to both HIRT0 (0.827 +/- 0.006) and TT22 (0.822 +/- 0.008). CONCLUSIONS: Our data suggest that shorter HIRT sessions may increase REE after exercise to a greater extent than TT and may reduce RR hence improving fat oxidation. The shorter exercise time commitment may help to reduce one major barrier to exercise.

Concepts: Physical exercise, Exercise, Training, Strength training, Weight training, Trigraph, Gh, Order theory


In Canada, 31.5 % of children are overweight or obese, putting them at an increased risk of chronic co-morbidities and premature mortality. Physical activity, healthy eating, and screen time are important behavioural determinants of childhood overweight and obesity that are influenced by the family environment, and particularly parents' support behaviours. However, there is currently a limited understanding of which types of these support behaviours have the greatest positive impact on healthy child behaviours. This study aims to determine the relative contribution of different types of parental support behaviours for predicting the likelihood that children meet established guidelines for daily physical activity, daily fruit and vegetable consumption, and recreational screen time.

Concepts: Epidemiology, Nutrition, Obesity, Physical exercise, Overweight, Child, Childhood, Dieting