Muscle wasting in rheumatoid arthritis:The role of oxidative stress

Rheumatoid arthritis(RA), the commonest inflammatory arthritis, is a debilitating disease leading to functional and social disability. In addition to the joints, RA affects several other tissues of the body including the muscle. RA patients have significantly less muscle mass compared to the general population. Several theories have been proposed to explain this. High grade inflammation, a central component in the pathophysiology of the disease, has long been proposed as the key driver of muscle wasting. More recent findings however, indicate that inflammation on its own cannot fully explain the high prevalence of muscle wasting in RA. Thus, thecontribution of other potential confounders, such as nutrition and physical activity, has also been studied. Results indicate that they play a significant role in muscle wasting in RA, but again neither of these factors seems to be able to fully explain the condition. Oxidative stress is one of the major mechanisms thought to contribute to the development and progression of RA but its potential contribution to muscle wasting in these patients has received limited attention. Oxidative stress has been shown to promote muscle wasting in healthy populations and people with several chronic conditions. Moreover, all of the aforementioned potential contributors to muscle wasting in RA(i.e., inflammation, nutrition, and physical activity) may promote pro- or antioxidative mechanisms. This review aims to highlight the importance of oxidative stress as a driving mechanism for muscle wasting in RA and discusses potential interventions that may promote muscle regeneration via reduction in oxidative stress.

Effects of resistance training on cardiovascular health in non-obese active adolescents

AIM:To determine the benefits of a 10-wk resistance training programme on cardiovascular health in nonobese and active adolescents.METHODS:This is a pragmatic randomised controlled intervention.The study was carried out in a Hong Kong Government secondary school.Thirty-eight lean and active boys and girls were randomised to either the resistance training group or the control group.Students in the resistance training group received in-school 10-wk supervised resistance training twice per week,with each session lasting 70 min.Main outcome measures taken before and after training included brachial endothelial dependent flow-mediated dilation,body composition,fasting serum lipids,fasting glucose and insulin,high sensitive C-reactive protein,24-h ambulatory blood pressure and aerobic fitness.RESULTS:The only training related change was in endothelial dependent flow-mediated dilation which increased from 8.5%to 9.8%.A main effect of time and an interaction(P<0.005) indicated that this improvement was a result of the 10-wk resistance training.Main effects for time(P<0.05) in a number of anthropometric,metabolic and vascular variables were noted;however,there were no significant interactions indicating the change was more likely an outcome of normal growth and development as opposed to a training effect.CONCLUSION:Ten weeks of resistance training in school appears to have some vascular benefit in active,lean children.

Physical activity and obese children

Childhood obesity is an epidemic of global proportions,accompanied by an alarming increase in various metabolic disorders.It would appear that childhood obesity stems largely from excessive energy intake and that it is the ensuing obesity that leads to physical inactivity in children,as opposed to initial physical inactivity inducing obesity.How changes in body composition that accompany obesity influence physical activity (PA) and the mechanistic basis for this remains poorly understood.This review provides an overview of the PA habits and body composition of the obese children.We suggest skeletal muscle metabolism as a key driver of PA.The role both quantitative and qualitative changes in skeletal muscle may play in oxidative metabolism in the obese children are discussed.There is a real need for research examining the mechanistic basis of physical inactivity in the obese.The dearth of information on the role of skeletal muscle metabolism in the PA of obese youngsters and the emergence of new technologies allowing cellular and metabolite mechanisms to be explored provides plenty of scope for future work.

Fundamental movement skills training to promote physical activity in children with and without disability： A pilot study

Background： A positive association between fundamental movement skills （FMS） and physical activity （PA） has been shown in previous research of children with and without disability. This pilot study explored a causal mechanism for such relationship, and hypothesized that when FMS proficiency is improved, enhanced PA uptake will be found in children with and without disability. It was further hypothesized that improving FMS proficiency will have a greater impact on children with disability than those without disability. Methods： Participants include typically developing （TD） children without disability and children with cerebral palsy （CP）, who were allocated to FMS training groups （CP-FMS n = 12, TD-FMS n = 13） and control groups （CP-C n = 12, TD-C n = 13）. Training groups practiced five FMS （run, jump, kick, throw, catch） in weekly 45-min sessions for 4 weeks. Control groups had their regular physiotherapy （CP） or physical education （TD） sessions. FMS were evaluated using process- and product-oriented measures, and PA was measured using accelerometers, before and after training. Results： It was verified that training groups gained improvements in FMS while control groups did not. No significant changes in weekday PA were found. Increased weekend moderate to vigorous physical activity （MVPA） was found in the CP-FMS group, while decreased weekend sedentary time was found in the CP-FMS and TD-FMS groups. The percentages of participants who exceeded the minimum detectable change （MDC9o） in MVPA and sedentary time were larger in children with CP than in children without disability. Conclusion： The findings suggest that improved FMS proficiency could potentially contribute to heightened PA and decreased sedentary time during weekends for children. Such effect of improved FMS proficiency on PA appears to be greater in those with physical disability than in those without disability. It is recommended that the findings of this pilot study should be further examined in future research.

Health through martial arts training: Physical fitness and reaction time in adolescent Taekwondo practitioners

Taekwondo (TKD) is a popular sport among adolescents, but the potential benefits of TKD training to young individuals are not well understood. The objectives of this cross-sectional exploratory study were to compare flexibility, muscular endurance, body composition, and simple reaction time between TKD-trained adolescents and controls. Twenty TKD-trained adolescents aged between 10 and 14 and 20 age-matched healthy controls were asked to perform five physical fitness tests: a sit-and-reach test, leg split test, skinfold measurement, one-minute curl-up test, and ruler-drop reaction time test. The results revealed no significance differences between the two groups in sit-and-reach distance (p = 0.690), leg split angle (p = 0.789), percentage of body fat (p = 0.342), or number of repetitions in the one-minute curl-up test (p = 0.250). However, the TKD group had significantly faster reaction times in the rulerdrop test than the control group (p = 0.005). The results thus suggest that although TKD training may improve reaction times in adolescents, it may have little effect on flexibility, muscular endurance, and body composition (percentage of fat). TKD may be a suitable exercise for improving simple reaction time, but it may not be suitable for improving general physical fitness in adolescents.