Changes in electrolytes and uric acid excretion during and after a 100 km run.

Physical activity leads to changes in water and electrolyte homeostasis and to enhanced purine metabolism. The typical abnormalities observed after exercise are hyperkaliemia, hyper- or hyponatremia and hyperuricemia. The possible explanations of hyperuricemia are: increased metabolism and decreased elimination of uric acid. Changes in uric acid excretion are commonly observed in disturbances of sodium and water homeostasis. The aim of this study was to evaluate changes in electrolytes and uric acid excretion during a very long period of exercise. Twenty subjects with a mean age of 40.75±7.15 years took part in a 100 km run. The route of the run was based on the university stadium track. All subjects were experienced amateur runners, with a mean time of regular running of 6.11±7.19 years. Blood was collected before the start, after every 25 km and 12 hours after the run. The levels of electrolytes, creatinine, uric acid, cortisol, aldosterone, creatine kinase, C-reactive protein and interleukin-6 were measured. Creatinine clearance, urinary potassium-to-sodium ratio, fractional excretion of electrolytes and uric acid were calculated. Seventeen runners completed the study. Significant increases in sodium (from 141.65±1.90 to 144.29±3.65mmol/l), potassium (from 4.53±0.34 to 5.03±0.42mmol/l), creatinine (from 0.88±0.11 to 1.10±0.20mg/dl) and uric acid (from 5.15±0.87 to 5.94±1.50 mg/dl) were observed after 100 km (p less than 0.05). Other significant changes during the study were noted in fractional excretions of sodium (from 0.86±0.29 to 0.33±0.13%) and potassium (from 6.66±2.79 to 18.90±10.01%), probably reflecting the decrease in renal blood flow (RBF) and increase in renal tubule reabsorption. The fractional excretion of uric acid slightly increased but without statistical significance from 5.34±1.51 to 6.09±2.34%. The results of our study showed that during very long but not very intensive exercise there is no change in uric acid excretion, although at the same time profound changes in electrolyte excretion are found. Both hyperuricemia and hyperuricosuria may be harmful, therefore it seems logical that the best way to avoid those abnormalities is to maintain fractional uric acid excretion.

The effect of the competitive season in professional basketball on inflammation and iron metabolism.

Following acute physical activity, blood hepcidin concentration appears to increase in response to exercise-induced inflammation, but the long-term impact of exercise on hepcidin remains unclear. Here we investigated changes in hepcidin and the inflammation marker interleukin-6 to evaluate professional basketball players' response to a season of training and games. The analysis also included vitamin D (25(OH)D3) assessment, owing to its anti-inflammatory effects. Blood samples were collected for 14 players and 10 control non-athletes prior to and after the 8-month competitive season. Athletes' performance was assessed with the NBA efficiency score. At the baseline hepcidin correlated with blood ferritin (r = 0.61; 90% CL ±0.31), but at the end of the season this correlation was absent. Compared with the control subjects, athletes experienced clear large increases in hepcidin (50%; 90% CI 15-96%) and interleukin-6 (77%; 90% CI 35-131%) and a clear small decrease in vitamin D (-12%; 90% CI -20 to -3%) at the season completion. Correlations between change scores of these variables were unclear (r = -0.21 to 0.24, 90% CL ±0.5), but their uncertainty generally excluded strong relationships. Athletes were hence concluded to have experienced acute inflammation at the beginning but chronic inflammation at the end of the competitive season. At the same time, the moderate correlation between changes in vitamin D and players' performance (r = 0.43) was suggestive of its beneficial influence. Maintaining the appropriative concentration of vitamin D is thus necessary for basketball players' performance and efficiency. The assessment of hepcidin has proven to be useful in diagnosing inflammation in response to chronic exercise.

A single oral intake of arginine does not affect performance during repeated Wingate anaerobic test.

AIM: The ergogenic effect of arginine has been demonstrated in research focusing on its intake before exercise. However, in these studies, the effect of arginine in combination with other various metabolites were assessed. The aim of this study was to determine whether a single oral intake of arginine, without any other compounds, 60 minutes prior to exercise, modifies performance and exercise metabolism during a repeated Wingate anaerobic test. METHODS: Six healthy, active, but not highly trained volunteers participated in the study. Subjects performed three 30s all-out supramaximal Wingate Anaerobic Tests (WAnTs) with 4 minute-interval rest periods between WAnTs. RESULTS: Arginine ingestion before exercise did not influence physical performance. Triple WAnTs resulted in a marked increase in white blood cell (WBC) count, lactate and ammonia concentrations, however there were no differences between arginine and the placebo trials. CONCLUSION: Our data indicated that 2 g of arginine ingested in a single dose, neither induced nitrite/nitrate (NOx) concentrations changes, nor improved physical performance.