This study investigated the effects of combined sleep deprivation and strenuous exercise on cognitive and neurobehavioral performance among long-distance runners completing one of the most difficult ultramarathons in the world. Seventeen runners participated. Each had a wrist-worn actigraph throughout the race to record their sleep time. In addition, each individual's performance in 10-min response-time tests before and after the race was recorded and a questionnaire enabled participants to report any difficulties they experienced during the competition. During race completion times of 27 to 44 h, combined acute lack of sleep (12 ± 17 min of rest during the race) and strenuous exercise (168.0 km) had marked adverse effects on cognitive performances ranging from mere lengthening of response time to serious symptoms such as visual hallucinations. This study suggests that regardless of rest duration and time in race, cognitive performances of ultramarathoners are adversely affected.

The aim of this study was to determine thresholds for various intensities of physical activity in children and adolescents using the RT3 accelerometer. Forty healthy participants aged 10-16 years were recruited to the study. To validate the RT3 accelerometer data, an independent sample of 20 children and adolescents aged 10-16 years performed the same activities. Accelerometer data, heart rate, and oxygen consumption were measured at nine levels of physical activity, which varied in intensity: sedentary, light, moderate, and vigorous. Age and sex did not affect thresholds. The activity categories and accelerometer counts were: sedentary activity, 0-40 counts x min(-1); light activity, 41-950 counts x min(-1); moderate activity, 951-3410 counts x min(-1); and vigorous activity, >3410 counts x min(-1), respectively. These thresholds were considered valid as the difference between threshold values obtained using two independent groups of children was not significant. This study has established threshold values for various physical activities and enables the RT3 accelerometer to be used to quantify the duration of various levels of activity in adolescents under free-living conditions.

These results confirm that obese pubertal boys have fat-free mass decreased capacities to use fat during moderate exercise. The findings suggest that obese boys need to practise physical activity at a lower intensity than healthy boys to enhance lipolysis and diminish adipose tissue and the consequences of obesity.