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AIM: The main goal of the present work is to establish the positive influence high-impact physical exercise, specifically high-level basketball, on bone acquisition in adolescent female and verify if the long-term exposure to such programs is the major modifiable factor explaining bone acquisition during adolescence. METHODS: A prospective cohort study comparing the development of bone mass in the lumbar spine, proximal femur and distal radius was carried out over a three-year period in two groups of adolescents: elite basketball players and age-matched controls. Baseline hormone levels and bone remodelling were evaluated. Bone mass, hours of physical exercise, diet, unhealthy habits, anthropometry and menstrual cycle were assessed at baseline and yearly. Differences in acquisition of bone mass were assessed by two-way repeated measures analysis of variance (ANOVA). RESULTS: Elite basketball training and competition appears to increase bone mass in girls aged 14-18 years. The most pronounced benefits were observed in lumbar spine and proximal femur, sites most directly involved in the exercise and subjected to greatest impact. CONCLUSION: The intensive basketball training and competition in adolescent females increases bone mass in the lumbar spine and femur, skeletal sites submitted to high impact in this sport. No significant gain in bone mass was observed in age-matched, normally active, controls.

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The effect of heavy, long duration aerobic exercise on low density lipoprotein (LDL) susceptibility to oxidation and on distribution of LDL subfractions was studied. Six well-trained runners, previously fasted, ran continuously for 4 h. Controlled intake of liquid and food was permitted during exercise. Total plasma and LDL triglyceride increased significantly. LDL susceptibility to oxidation, measured as conjugated dienes formation, was modified significantly (P < or = 0.05) after running (14% reduction in lag phase time, and 8% increase in maximal curve slope). The percentage of electronegative LDL form (named LDLB) also increased significantly (P < or = 0.05) after exercise both basally (from 7.3% to 11%) and after 2h of induced oxidation (from 40.6% to 52.3%). Neither LDL susceptibility to oxidation nor increase of LDLB was statistically associated with food consumed during the race or modifications of triglycerides suggesting that this effect was due to exercise rather than food-related. The pattern of LDL subfractions was type A in all athletes before and after running. The oxidative LDL changes, seen in exercise conditions similar to those of hard training or competition, demonstrated an unfavourable effect of very intense exercise on lipoprotein metabolism.

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Regular practice of dynamic physical exercise produces cardiovascular, metabolical, biochemical, hematological and endocrine changes among the most important ones. To reach the majority of these effects, it is not necessary to perform particularly intense training. The equivalent to one hour of active walking per day would be sufficient. However, the improvement of the physical condition is only achieved with specific training programmes. Changes originated by training are due to the effects of the actual exercise and to the modifications of the cardiovascular risk factors. Apart from this, the repercussion of regular physical exercise on conduct and personality should not be underestimated. Physical exercise is a complementary treatment measure which turns out to be the more efficacious the best prevention measures and conventional treatments are complied with.

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Serum creatine kinase isoenzyme 2 concentrations (CK 2 mass) were measured in marathon runners during training and 1 and 2 days after a race and compared with values from 36 acute myocardial infarction (AMI) patients whose total CK and (or) CK 2 activities were similar to those of runners in the basal state. During training, runners had CK and CK 2 activities 53% and 43% above reference values, respectively, and 36% had CK 2 activity > 5% of total CK. Nine runners (26%) showed CK 2 mass values > 6 micrograms/L but < or = 10 micrograms/L; 35 of the AMI subjects, despite having CK activities similar to those of runners, had values > 10 micrograms/L. The ratio of CK 2 mass to total CK activity was significantly (P < 0.0002) different between sexes for runners. At 1 and 2 days after racing, 100% of CK and CK 2 activities and 71% and 57% of the percentages of CK 2 activity, respectively, were abnormally high; 57% and 43% of CK 2 mass values were > 10 micrograms/L, being comparable with those observed for the AMI group. Basal CK 2 mass values of the runners appeared only slightly higher than that for sedentary subjects, but after exercise half the subjects presented increased values similar to those observed for AMI subjects. The ratio of CK 2 mass to total CK activity appeared unaltered by exercise in all but one of the samples assayed, indicating its utility in evaluating CK 2 mass increases originating in skeletal muscle.

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