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The growing consumer awareness regarding health and fitness has been leading to a huge rise in the consumption of nutritional supplements and, consequently, to an increase in concerns about their quality. In this sense, one of the most consumed products is protein supplements and, despite being safer than other types of supplements, there are several studies showing incompatibilities between what is present on the labels and their actual content. Therefore, this review is focused on gathering information about the problems arising from poor manufacturing practices and inadequate quality control of sport protein supplements. These issues are mainly related to three aspects: reduction of the supplements’ nutritional value, the presence of pharmacological substances, and contamination with microorganisms or toxic metals. Regarding the first aspect, reports about the “classic” addition of nitrogen-rich compounds to mask the protein content measured by the Kjeldahl method were discussed, as well as recent topics such as the addition of cheaper proteins to produce an “undetectable” adulteration in whey protein supplements. With respect to the presence of pharmacological compounds, it is a finding that is not very common in protein supplements; however, even trace amounts of foreign substances in this type of product may cause adverse effects to consumers, and, in the case of an elite athlete, may result in doping. Finally, we discuss about the contamination with microorganisms and toxic metals, this latter being a subject that should be further explored due to few studies in the literature.

The role of lifestyle behaviors on neck adipose tissue (NAT), a fat depot that appears to be involved in the pathogenesis of different cardiometabolic diseases and in inflammatory status, is unknown. In this cross-sectional and exploratory study, the authors examined the relationship between sedentary time and physical activity (PA) with neck adiposity in young adults. A total of 134 subjects (69% women, 23 ± 2 years) were enrolled. The time spent in sedentary behavior and PA of different intensity were objectively measured for 7 consecutive days (24 hr/day), using a wrist (nondominant)-worn accelerometer. The NAT volume was assessed using computed tomography, and the compartmental (subcutaneous, intermuscular, and perivertebral) and total NAT volumes were determined at the level of vertebra C5. Anthropometric indicators and body composition (by dual-energy X-ray absorptiometry) were determined. The time spent in light physical activity and moderate physical activity (MPA) and the overall PA were inversely associated with the intermuscular NAT volume in men, as were the MPA and overall PA with total NAT volume (all ps ≤ .04). Sedentary time was directly related to the total NAT volume (p = .04). An opposite trend was observed in women, finding a direct relationship of MPA with the subcutaneous NAT; of light physical activity, MPA, and overall PA with the perivertebral NAT; and of light physical activity with total NAT volumes (all ps ≤ .05). The observed associations were weak, and after adjusting for multiplicity, the results became nonsignificant (p > .05). These findings suggest that the specific characteristics of PA (time and intensity) might have sex-dependent implications in the accumulation of NAT.

This systematic review and meta-analysis examined the effects of creatine supplementation on recovery from exercise-induced muscle damage, and is reported according to the PRISMA guidelines. MEDLINE and SPORTDiscus were searched for articles from inception until April 2020. Inclusion criteria were adult participants (≥18 years); creatine provided before and/or after exercise versus a noncreatine comparator; measurement of muscle function recovery, muscle soreness, inflammation, myocellular protein efflux, oxidative stress; range of motion; randomized controlled trials in humans. Thirteen studies (totaling 278 participants; 235 males and 43 females; age range 20–60 years) were deemed eligible for analysis. Data extraction was performed independently by both authors. The Cochrane Collaboration Risk of Bias Tool was used to critically appraise the studies; forest plots were generated with random-effects model and standardized mean differences. Creatine supplementation did not alter muscle strength, muscle soreness, range of motion, or inflammation at each of the five follow-up times after exercise (<30 min, 24, 48, 72, and 96 hr; p > .05). Creatine attenuated creatine kinase activity at 48-hr postexercise (standardized mean difference: −1.06; 95% confidence interval [−1.97, −0.14]; p = .02) but at no other time points. High (I²; >75%) and significant (Chi²; p < .01) heterogeneity was identified for all outcome measures at various follow-up times. In conclusion, creatine supplementation does not accelerate recovery following exercise-induced muscle damage; however, well-controlled studies with higher sample sizes are warranted to verify these conclusions. Systematic review registration (PROSPERO CRD42020178735).

Rapid weight loss or “weight cutting” is a common but potentially harmful practice used in mixed martial arts competition. Following the official weigh-in, competitors refeed and rehydrate themselves in a process known as rapid weight gain (RWG) to realize a potential competitive advantage. While data from surveys and small series have indicated the majority of mixed martial arts athletes engage in rapid weight loss, there is a lack of officially collected data from sanctioning organizations describing its prevalence. The present investigation represents a summary of the data collected between December 2015 and January 2018 by the California State Athletic Commission. In total, 512 professional mixed martial artists (455 males and 57 females) were included. Of these, 503 (98%) athletes gained body mass between weigh-in and their bouts. Total RWG between weigh-in and competition was 5.5 ± 2.5 kg, corresponding to an 8.1% ± 3.6% body mass increase. Total RWG was 5.6 ± 2.5 kg (8.1% ± 3.6%) for males and 4.5 ± 2.3 kg (8.0% ± 3.8%) for females. More than one quarter of men and one third of women gained >10% body mass between weigh-in and competition. Athletes from leading international promotions gained more absolute, but not relative, body mass than those from regional promotions. Our findings indicate RWG is nearly ubiquitous in professional , with a similar prevalence in male and female athletes. Trends based on promotion suggest a larger magnitude of RWG in presumably more experienced and/or successful mixed martial artists from leading international promotions.