We aimed to evaluate whether an intervention program emphasizing in increased fluid intake can improve exercise performance in children exercising in the heat. Ninety-two young athletes participated in the study (age: 13.8 ± 0.4 years, weight: 54.9 ± 1.5 kg). Thirty-one (boys: 13, girls: 18) children served as the control group (CON) and 61 (boys: 30, girls: 31) as the intervention (INT). Volunteers had free access to fluids. Hydration was assessed on the basis of first morning urine. A series of field tests were used to evaluate exercise performance. All tests occurred outdoors in the morning (mean ambient temperature=28 °C). After baseline testing, INT attended a lecture on hydration, and urine color charts were mounted in all bathrooms. Additionally, water accessibility was facilitated in training, dining and resting areas. Hydration status was improved significantly in the INT [USG: pre=1.031 ± 0.09, post=1.023 ± 0.012, P<0.05; urine osmolality (mOsm/kg water): pre=941 ± 30, post=782 ± 34, P<0.05], while no statistically significant changes were found in the CON [USG: pre=1.033 ± 0.011, post=1.032 ± 0.013, P>0.05; urine osmolality (mOsm/kg water) 970 ± 38 vs 961 ± 38, P>0.05]. Performance in an endurance run was improved significantly only in INT (time for 600 m: pre=189 ± 5 s, post=167 ± 4 s, P<0.05). Improving hydration status by ad libitum consumption of water can enhance performance in young children exercising in the heat.

Eighteen lambs (L) and 18 goats (G), 12 weeks of age, were allocated in equal numbers to three diets. The basal (B) diet had no added copper (Cu) while the other two had 30 or 60 mg added Cu per kg dry matter (DM) as CuSO 4 .5H 2 O. Lambs and goats were housed and fed individually. After 67 days, deaths from Cu toxicity occurred only in lambs from groups L-30 (basal diet + 30 mg Cu per kg DM) and L-60 (basal diet + 60 mg Cu per kg DM). The remaining lambs and all of the goats were slaughtered at 91 and 137 days respectively.A decreased food intake and loss of weight were observed in some lambs towards the end of the experiment which appeared to be associated with an approaching haemolytic crisis. The additional dietary Cu had a positive effect on food conversion efficiency only in the early stages of the experiment in both lambs and goats. None of the goats died or lost weight.Plasma Cu concentrations and serum glutamate oxalacetate transaminase and creatine kinase activities were elevated in lambs of groups L-30 and L-60 after 2 months, while in goats the concentrations were in normal ranges during the whole experimental period.Additional dietary Cu increased significantly the Cu concentrations of liver, kidney, muscle, spleen, heart, brain, hair and faeces in both lambs and goats. Additional Cu decreased the fresh and dry liver weights of lambs and the liver to live weight ratio whereas the corresponding values for kidneys were increased. The differences between groups of goats in fresh or dry liver and kidney weights were not significant, though the fresh and dry liver weights tended to be higher in groups G-30 and G-60 compared with those in the group G-B.The amount of Cu stored in the livers of the lambs was six to nine times higher than that of the goats. Differences in Cu storage between lambs and goats may be related to species differences in Cu utilization and hence resistance to Cu toxicity.

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