BackgroundWhile overall physical activity is clearly associated with a better short-term and long-term health, prolonged strenuous physical activity may result in a rise in acute levels of blood-biomarkers used in clinical practice for diagnosis of various conditions or diseases. In this study, we explored the acute effects of a full Ironman-distance triathlon on biomarkers related to heart-, liver-, kidney- and skeletal muscle damage immediately post-race and after one week’s rest. We also examined if sex, age, finishing time and body composition influenced the post-race values of the biomarkers.MethodsA sample of 30 subjects was recruited (50% women) to the study. The subjects were evaluated for body composition and blood samples were taken at three occasions, before the race (T1), immediately after (T2) and one week after the race (T3). Linear regression models were fitted to analyse the independent contribution of sex and finishing time controlled for weight, body fat percentage and age, on the biomarkers at the termination of the race (T2). Linear mixed models were fitted to examine if the biomarkers differed between the sexes over time (T1-T3).ResultsBeing male was a significant predictor of higher post-race (T2) levels of myoglobin, CK, and creatinine levels and body weight was negatively associated with myoglobin. In general, the models were unable to explain the variation of the dependent variables. In the linear mixed models, an interaction between time (T1-T3) and sex was seen for myoglobin and creatinine, in which women had a less pronounced response to the race.ConclusionOverall women appear to tolerate the effects of prolonged strenuous physical activity better than men as illustrated by their lower values of the biomarkers both post-race as well as during recovery.

The results suggested that coaches in the present study were not aware of the latest recommendations and guidelines regarding strength training for youth.

In this study we have investigated the effectiveness of a one day school-based intervention with recreational fishing (in Swedish called Klassdraget) in increasing environmental awareness, interest in nature and recreational fishing in pupils aged between 8 and 12. Our results suggest a weak positive association between exposure to natural environments in a recreational fishing context and interest in nature and recreational fishing. We found the intervention to have no effect on the frequency of fishing, interest in fishing more, or number of visits in nature during spare time. Knowledge about nature and possibly also environmental awareness are positively affected and these effects can be traced as long as three years after the intervention. Our findings also reveal a low correlation between frequency of nature visits and self-reported interest in nature. The observed effects of Klassdraget are small but appear to be larger for girls, who are traditionally less interested in recreational fishing when compared with boys.

Background A growing body of evidence suggests that exposure to nature is beneficial for human health. However, the observed health effect of nature may be mediated by physical activity and that humans are physically active at a higher intensity outdoors compared to when they are physical active indoors. Objective This study examines the variation of heart rate and power output for a fixed rating of perceived exertion in a group of healthy older adults in three different environments representing three levels of exposure to nature. Methods To this randomized, 3-by-3 crossover design study, healthy older adults (≥65 years) were recruited from local gyms. All participants participated in three experimental conditions; indoors, simulated outdoors and outdoor environments, in a randomized order. The participants exercised for 20 minutes at an intensity equivalent to a rating of 11–13 on the Borg scale for perceived exertion (RPE). Measurements of heart rate, power output (Watt) and ratings of perceived exertion were taken at minutes 1 to 6 and at minute 20. To examine the effect of the environment on heart rate and power, linear mixed models were used. Results In all, 48 participants (56% females) were included in the analysis. No significant main effects on the outcomes were observed for power output (p = 0.073, η2 = 0.04) or heart rate (p = 0.067, η2 = 0.04) Conclusion No significant effect on the outcomes was observed. However, borderline significant outcomes for power output or heart rate outdoors in nature, along with previous studies in the field, indicates that such an effect cannot be completely ruled out, but any effect is likely to be small. Future research examining health benefits of the independent exposure to nature are encouraged to adjust for the dose of physical activity. Trial registration ID: ISRCTN22230544.

this study examines the association between aerobic capacity and biomarkers of skeletal-and cardiac muscle damage among amateur triathletes after a full distance ironman. Men and women (n = 55) were recruited from local sport clubs. One month before an Ironman triathlon, they conducted a 20 m shuttle run test to determine aerobic capacity. Blood samples were taken immediately after finishing the triathlon, and analyzed for cardiac troponin t (ctnt), Myosin heavy chain-a (MHc-a), n-terminal prohormone of brain natriuretic peptide (nt-proBnp), creatin Kinas (cK), and Myoglobin. Regression models examining the association between the biomarkers and aerobic capacity expressed in both relative terms (mLO2*kg −1 *min −1) and absolute terms (LO2*min −1) controlled for weight were fitted. A total of 39 subjects (26% females) had complete data and were included in the analysis. No association between aerobic capacity and cardiac muscle damage was observed. for myoglobin, adding aerobic capacity (mLO2*kg −1 *min −1) increased the adjusted r 2 from 0.026 to 0.210 (F: 8.927, p = 0.005) and for cK the adjusted r 2 increased from-0.015 to 0.267 (F: 13.778, p = 0.001). In the models where aerobic capacity was entered in absolute terms the adjusted r 2 increased from 0.07 to 0.227 (F: 10.386, p = 0.003) for myoglobin and for CK from-0.029 to 0.281 (F: 15.215, p < 0.001). A negative association between aerobic capacity and skeletal muscle damage was seen but despite the well-known cardioprotective health effect of high aerobic fitness, no such association could be observed in this study.