Sex-specific heterosis in line crosses of mice selectively bred for high locomotor activity.

When populations with similar histories of directional selection are crossed, their offspring may differ in mean phenotype as compared with the average for the parental populations, often exhibiting enhancement of the mean phenotype (termed heterosis or hybrid vigor). We tested for heterosis in a cross of two replicate lines of mice selectively bred for high voluntary wheel running for 53 generations. Mice were paired to produce four sets of F1 offspring: two purebred High Runner (HR) lines and the hybrid reciprocal crosses. The purebred HR showed statistically significant, sex-dependent differences in body mass, wheel revolutions, running duration, mean running speed, and (controlling for body mass) organ masses (heart ventricles, liver, spleen, triceps surae muscle). Hybrid males ran significantly more revolutions than the purebred males, mainly via increased running speeds, but hybrid females ran intermediate distances, durations, and speeds, as compared with the purebred females. In both sexes, ventricles were relatively smaller in hybrids as compared with purebred HR. Overall, our results demonstrate differential and sex-specific responses to selection in the two HR lines tested, implying divergent genetic architectures underlying high voluntary exercise.

The biological control of voluntary exercise, spontaneous physical activity and daily energy expenditure in relation to obesity: human and rodent perspectives.

Mammals expend energy in many ways, including basic cellular maintenance and repair, digestion, thermoregulation, locomotion, growth and reproduction. These processes can vary tremendously among species and individuals, potentially leading to large variation in daily energy expenditure (DEE). Locomotor energy costs can be substantial for large-bodied species and those with high-activity lifestyles. For humans in industrialized societies, locomotion necessary for daily activities is often relatively low, so it has been presumed that activity energy expenditure and DEE are lower than in our ancestors. Whether this is true and has contributed to a rise in obesity is controversial. In humans, much attention has centered on spontaneous physical activity (SPA) or non-exercise activity thermogenesis (NEAT), the latter sometimes defined so broadly as to include all energy expended due to activity, exclusive of volitional exercise. Given that most people in Western societies engage in little voluntary exercise, increasing NEAT may be an effective way to maintain DEE and combat overweight and obesity. One way to promote NEAT is to decrease the amount of time spent on sedentary behaviours (e.g. watching television). The effects of voluntary exercise on other components of physical activity are highly variable in humans, partly as a function of age, and have rarely been studied in rodents. However, most rodent studies indicate that food consumption increases in the presence of wheels; therefore, other aspects of physical activity are not reduced enough to compensate for the energetic cost of wheel running. Most rodent studies also show negative effects of wheel access on body fat, especially in males. Sedentary behaviours per se have not been studied in rodents in relation to obesity. Several lines of evidence demonstrate the important role of dopamine, in addition to other neural signaling networks (e.g. the endocannabinoid system), in the control of voluntary exercise. A largely separate literature points to a key role for orexins in SPA and NEAT. Brain reward centers are involved in both types of physical activities and eating behaviours, likely leading to complex interactions. Moreover, voluntary exercise and, possibly, eating can be addictive. A growing body of research considers the relationships between personality traits and physical activity, appetite, obesity and other aspects of physical and mental health. Future studies should explore the neurobiology, endocrinology and genetics of physical activity and sedentary behaviour by examining key brain areas, neurotransmitters and hormones involved in motivation, reward and/or the regulation of energy balance.

Injuries Sustained by the Mixed Martial Arts Athlete.

CONTEXT: Mixed martial arts (MMA) is rapidly growing in popularity in the United States and abroad. This combat sport joins athletes from a wide variety of martial art disciplines, each with characteristic and distinguishing injury profiles, together in competition. Because of increasing participation by professionals and amateurs alike, injuries sustained by MMA athletes have been on the rise. EVIDENCE ACQUISITION: A review of relevant publications using the search term mixed martial arts and each of its component combat sports (eg, Muay Thai, Brazilian jiu-jitsu) from 1980 through 2015 was completed using PubMed and Google Scholar. STUDY DESIGN: Clinical review. LEVEL OF EVIDENCE: Level 5. RESULTS: The majority of studies on MMA injuries evaluate those sustained during competition, which range in incidence from 22.9 to 28.6 per 100 fight-participations. Striking-predominant disciplines such as boxing, karate, and Muay Thai have high rates of head and facial injuries, whereas submission-predominant disciplines such as Brazilian jiu-jitsu, judo, and wrestling have high rates of joint injuries. CONCLUSION: Numerous studies have evaluated injuries in athletes who participate in MMA and its component disciplines during competition but much remains to be discovered about injuries sustained during training and in specific patient populations such as adolescents and women.

An Early Warning Score Predicts Risk of Death after In-hospital Cardiopulmonary Arrest in Surgical Patients.

In-hospital cardiopulmonary arrest can contribute significantly to publicly reported mortality rates. Systems to improve mortality are being implemented across all specialties. A review was conducted for all surgical patients >18 years of age who experienced a "Code Blue" event between January 1, 2013 and March 9, 2014 at a university hospital. A previously validated Modified Early Warning Score (MEWS) using routine vital signs and neurologic status was calculated at regular intervals preceding the event. In 62 patients, the most common causes of arrest included respiratory failure, arrhythmia, sepsis, hemorrhage, and airway obstruction, but remained unknown in 27 per cent of cases. A total of 56.5 per cent of patients died before hospital discharge. In-hospital death was associated with American Society of Anesthesiologists status (P = 0.039) and acute versus elective admission (P = 0.003). Increasing MEWS on admission, 24 hours before the event, the event-day, and a maximum MEWS score on the day of the event increased the odds of death. Max MEWS remained associated with death after multivariate analysis (odds ratio 1.39, P = 0.025). Simple and easy to implement warning scores such as MEWS can identify surgical patients at risk of death after arrest. Such recognition may provide an opportunity for clinical intervention resulting in improved patient outcomes and hospital mortality rates.