The effect of caffeine ingestion on 8 km run performance in a field setting

The aim of this study was to assess the effect of caffeine ingestion on 8 km run performance using an ecologically valid test protocol. A randomized double-blind crossover study was conducted involving eight male distance runners. The participants ran an 8 km race 1 h after ingesting a placebo capsule, a caffeine capsule (3 mg x kg(-1) body mass) or no supplement. Heart rate was recorded at 5 s intervals throughout the race. Blood lactate concentration and ratings of perceived exertion were recorded after exercise. A repeated-measures analysis of variance (ANOVA) identified a significant treatment effect for 8 km performance time (P < 0.05); caffeine resulted in a mean improvement of 23.8 s (95% confidence interval [CI] = 13.1 to 34.5 s) in 8 km performance time (1.2% improvement, 95% CI = 0.7 to 1.8%). In addition, a two-way (time x condition) repeated-measures ANOVA identified a significantly higher blood lactate concentration 3 min after exercise during the caffeine trial (P < 0.05). We conclude that ingestion of 3 mg . kg(-1) body mass of caffeine can improve absolute 8 km run performance in an ecologically valid race setting.     

General and task-related experiences affect early object interaction

The effects of 2 weeks of no, general, and task-related enhanced movement experiences on 8- to 12-week-old infants' (N = 30) hand and foot interactions with objects were assessed using standard video and motion analysis. For hand-object interaction ability, general and task experience led to greater success than did no experience, and task experience led to greater success than did general experience. Only general experience led to greater success for foot-object interaction ability. Experiences therefore resulted in differential effects depending on which limbs infants used. The results suggest that different movement experiences can advance infants' earliest object interactions. They also indicate that even early purposeful behaviors result from a complex interplay of experience, current ability, and task demands.