Effects of sodium citrate ingestion before exercise on endurance performance in well trained college runners.

OBJECTIVE: To test the hypothesis that sodium citrate administered two hours before exercise improves performance in a 5 km running time trial. METHODS: A total of 17 male well trained college runners (mean (SD) O(2)MAX 61.3 (4.9) ml/kg/min) performed a 5 km treadmill run with and without sodium citrate ingestion in a random, double blind, crossover design. In the citrate trial, subjects consumed 1 litre of solution containing 0.5 g of sodium citrate/kg body mass two hours before the run. In the placebo trial, the same amount of flavoured mineral water was consumed. RESULTS: The time required to complete the run was faster in the citrate trial than the placebo trial (1153.2 (74.1) and 1183.8 (91.4) seconds respectively; p = 0.01). Lower packed cell volume and haemoglobin levels were found in venous blood samples taken before and after the run in the citrate compared with the placebo trial. Lactate concentration in the blood sample taken after the run was higher in the citrate than the placebo trial (11.9 (3.0) v 9.8 (2.8) mmol/l; p<0.001), and glucose concentration was lower (8.3 (1.9) v 8.8 (1.7) mmol/l; p = 0.02). CONCLUSION: The ingestion of 0.5 g of sodium citrate/kg body mass shortly before a 5 km running time trial improves performance in well trained college runners.

Effects of creatine supplementation during recovery from rapid body mass reduction on metabolism and muscle performance capacity in well-trained wrestlers.

BACKGROUND: The aim of the study was to test the hypothesis that creatine supplementation with concomitant carbohydrate ingestion during recovery period after rapid body mass reduction accelerates the restoration of body mass and physical performance in well-trained wrestlers. METHODS: A double-blind, placebo-controlled cross-over study was conducted on five young healthy male wrestlers, who reduced their body mass by 4.5-5.3% in two series of investigations separated by one month. During 17 hrs recovery period they consumed controlled diet supplemented in random order with glucose (GL trial) or with glucose plus creatine (GL+CR trial). The capacity of the subjects to perform submaximal and maximal (W(max)) intensity work was measured using 5 min intermittent intensity test exercise at the Cybex II device before (Test 1) and after body mass loss (Test 2), also after the recovery (Test 3) on both trials. RESULTS: There was no effect of treatment on the extent of body mass regain during 17 hrs recovery. A significant increase (19.2%) in W(max) from Test 2 to Test 3 was observed in GL+CR trial whereas no change was evident with GL treatment. A strong correlation (r=0.92) was established between the whole body creatine retention and the extent of change in W(max) from Test 2 to Test 3. CONCLUSIONS: The results suggest that creatine supplementation with concomitant glucose ingestion during 17 hrs recovery from rapid body mass loss does not accelerate the restoration of body mass but still stimulates the regain of physical performance in maximal intensity efforts in well-trained wrestlers.

Effect of creatine supplementation during rapid body mass reduction on metabolism and isokinetic muscle performance capacity.

Well-trained subjects (n = 6) were studied before and after losing a mean 3.0%-4.3% of body mass to determine whether muscle performance could be maintained or even enhanced by dietary creatine supplementation. During a 5-day period of loss of mass the subjects were randomly assigned to a creatine or placebo supplemented diet. All the subjects were measured before and after loss of mass on both supplements for isokinetic peak torque (PT) and work at peak torque (W(PT)) of knee extensors, also for intermittent high intensity working capacity of the same muscle group. The latter test consisted of submaximal isokinetic knee extensions at an angular velocity of 1.57 rad x s(-1) for 45 s at the rate of 30 contractions each min (submaximal work, Ws max) followed by 15-s maximal effort (maximal work, Wmax). Total duration of the test was 3 min. Haematocrit was measured and haemoglobin, ammonia, lactate, glucose and urea concentrations were analysed in blood samples obtained at rest and after cessation of muscle performance tests. The results indicated that creatine supplementation in comparison with placebo treatment during rapid body mass reduction may help to maintain muscle PT and W(PT)1 at high angular velocities, not influencing Wmax and the rate of fatigue development during Wmax, but affecting adversely Ws max. Within the limitations of the present study the reasons for the partially detrimental effect of creatine administration remain obscure, but it is suggested that impaired creatine uptake in muscle during body mass loss as well as creatine induced changes in muscle glucose and glycogen metabolism may be involved.

Effect of rapid weight loss on metabolism and isokinetic performance capacity. A case study of two well trained wrestlers.

The effect of rapid weight loss on metabolism and isokinetic performance of quadriceps femoris muscle in two well-trained wrestlers was investigated. Weight reduction by 5.1-5.8% during 3 days resulted in reduction of plasma volume by 7.4-14.8% and increase in blood urea concentration by 1.8-2.1 times. Blood lactate response to standardized 5-min isokinetic performance test exercise was not dependent on body weight status. Peak torque, time to peak torque, rate of peak torque development and maximal power output measured during single maximal contraction of the quadriceps femoris muscle, as well as muscle working ability measured during 5-min isokinetic performance test were all impaired as a result of weight reduction. Body weight of the subjects, plasma volume, blood urea concentration and muscle isokinetic performance characteristics did not return to the initial levels even after 16.5-hrs recovery period (with food and drink ad libitum) following weight loss. These findings suggest that rapid weight loss by ca 5-6% may interfere wrestlers' metabolism and impair the quadriceps femoris muscle function. Moreover, 16.5-hrs recovery period with food and drink loading may be not sufficient to eliminate the negative consequences of body weight manipulation.

Effect of creatine administration on blood urea level and postexercise glycogen repletion in liver and skeletal muscle in rats.

The aim of the present study was to assess the effect of creatinine administration on urea metabolism in sedentary and exercised Wistar rats and also on the rate of glycogen resynthesis in the liver and skeletal muscle of endurance-trained animals after exhausting exercise. Creatine treatment for 7 days significantly increased the concentration of urea in blood plasma of sedentary as well as exercised rats and this effect was also maintained in trained animals 24 h after exhausting swimming. The rate of glycogen resynthesis in the liver and skeletal muscle after glycogen-depleting exercise was not modified by creatine administration.