Delayed metabolic changes after strenuous exertion in trained young men

Twenty apparently healthy, young male volunteers, aged 18-25 (mean 19.3, SD 1.4) years received a 6 months standardized, graded outdoor physical training and were screened for serum magnesium concentration (S-Mg), serum calcium concentration (S-Ca), serum aspartate amino transferase (S-AST), serum alanine amino transferase (S-ALT), serum creatine kinase activity (S-CK), other laboratory variables, weight, and VO2 ml.kg-1.min-1 [corrected] (VO2 max), before a 70 km march, as well as at 1, 24 and 72 h and 18 days after. Maximal aerobic power, body weight, haemoglobin, haematocrit, serum creatinine, total protein and albumin remained unchanged throughout. Immediately after the march, S-Mg did not change, S-AST, S-ALT and S-CK rose, but the rise was not statistically significant, while small but significant rises in S-Ca (P less than 0.05, Student's t-test) and serum cholesterol (P less than 0.01) normalized at 24 h. At 72 h after the march, a significant fall in S-Mg was found (P less than 0.01), together with a second significant rise in S-Ca (P less than 0.05). After 18 days, with no intervening marches or dietary changes, S-Mg remained significantly lowered (P less than 0.05), mean S-ALT and S-CK became significantly raised for the first time (P less than 0.001 and P less than 0.01 respectively), whereas S-Ca normalized. Concomitantly, for the first time there was now a significant rise in blood sugar (P less than 0.001), serum triglycerides (P less than 0.01), and a second rise of serum cholesterol (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)