No description available.

No description available.

No description available.

No description available.

No description available.

Eight healthy males performed two rides to exhaustion at a work load corresponding to 125% Q02 max, one hr after ingesting either NaHCO3 (E) or NaCl (C). Mean + SE pre-exercise blood pH, HCO3 and base excess (BE) values were respectively 7.42 + 0.01, 28.2 + 1.5 mmol/l and 2.02 + 0.1 mmol/l for the E condition, and 7.39 + 0.01, 24.4 + 0.7 mmol/l and -0.4 + 0.7 mmol/l for the C condition (P < 0.05 for all variables). Cycling time to exhaustion (E = 100.66.1; C = 98.6 + 5.7 sec) and total "02 during recovery (E 17.7 + 0.9; C = 17.3 + 0.8 1/30 min) did not differ between treatments. Blood pH, HCO3 and BE were significantly higher while the hydrogen ion to lactate ratio (LH+I/ELAI) was significantly lower in E than in C during recovery. Blood LA levels were also greater in E than in C during the latter part of recovery although peak individual values were not significantly different between trials CE = 14.4 + 0.4; C = 13.3 + 0.0 mmol /1) . In view of the insignificant differences in cycling time, peakLA production was greater in E than in C. Rather it individual LA and total recovery 002, it is not likely that Given this protocol, alkalosis does not help to sustain an appears that LA efflux was enhanced by the NaHCO3 feeding. Additionally, the return of the acid-base status in blood to resting conditions was more rapid during alkalosis does not help to sustain an intense exercise bout. These data suggest, however, that NaHCO3 may be of benefit following repeated work bouts.

The purpose of this study was to investigate the influence of oral NaHCOa administration on the alteration of acid-base balance and performance of high-intensity interval swimming. Ten male college swimmers were studied on five test days within a two-week period. Each test day consisted of five 100-yd freestyle swims with a two-minute rest interval between each bout. Subjects received two NaHCO3, two placebo and one no-drink treatments for the five test days. One hour before the onset of swimming the subjects were given 300 ml of citric acid flavored solution containing either NaCl (placebo) or NaHC03 (experimental), or received no drink. The dose of NaHCO3 solution was 0.25 9/kg-1 body weight. Before the sprint trial test a 300-yd warmup swimming was performed followed by a nine-minute rest. Performance times for each 100-yd swim were recorded. Blood samples were obtained before and one hour after treatment, two minutes after warmup and the last bout of swim. Blood, pH, lactate, standard bicarbonate (SBC) and base excess (BE) were measured. After the statistical analysis had shown there were no differences between the corresponding values of two trials for the same treatment, the data for identical treatments were combined and reanalyzed statistically as one group. All the corresponding variables between placebo and no-drink revealed no differences. Performance times of the fourth and fifth swimming bouts were faster (P < 0.05) and blood lactate after exercise was higher (P < 0.05) in NaHCO3 condition. Blood pH, SBC, BE were higher (P < 0.05) at post-treatment, post-warmup and post-last bout of swim in NaHCO3 condition. The difference between NaHCO3 and the other two conditions on the increment of lactate (2.0 mM) was proportional to that on the decrement of SBC (2.2 meq/1) after exercise. The data from the placebo and NaHCO3 treatments shown a positive correlation between hydrogen ion and lactate concentrations (r = 0.923) and a negative correlation between SBC and lactate concentrations (r = -0.941) after warmup and exercise. These data are in agreement with previous findings that during repeated bouts of exercise pre-exercise administration of NaHCO3 improves performance, possibly by facilitating the efflux of lactate and hydrogen ions from working muscles and thereby delaying the onset of fatigue.

The aim of the studies described in this thesis was to investigate the effects of the intensity of treadmill walking and training status on lipoprotein metabolism in the fasted and postprandial states in normolipidaemic individ uals. Twelve young (28±2 years) adults walked on the treadmill on two occasions, for 90 min at low intensity (30% maximal oxygen uptake, V02max) and moderate intensity (60% V02max) after an overnight fast. Venous blood samples were taken during, immediately, 1 and 24 hours after the end of each walk, all in the fasted state. Both exercise bouts reduced the serum triacylglycerol (TAG) concentrations 24 hours after exercise but these decreases were independent of the intensity of the previous exercise bout. In the light of the suggestion that the fasted state may not be a sensitive model to study the TAG metabolic capacity, the above experiment was repeated in young adults (n=12), with the two bouts of treadmill walking taking place 16 hours prior to the ingestion of a high fat meal 0.3 g fat·kg body weight·l , 67% energy from fat). In addition a third trial was introduced in which volunteers did not exercise prior to the ingestion of the meal (control trial). Venous samples were obtained in the fasted state and after the ingestion of the meal at hourly intervals for 6 hours. Moderate, but not low intensity, walking significantly attenuated (26%) the total lipaemic response to the meal compared with the control trial (5.51±0.5 mmoJ.l-l.h vs 7.40±0.7 mmol·J-l·h; p<0.05). However, the moderate intensity bout expended twice the energy expended during low intensity exercise as the two bouts were of similar duration (90 min). The third study, therefore, examined the effect of the intensity of walking on the lipaemic responses to a similar high fat meal in young adults (n=9), when the energy expenditure of the two walking bouts was held constant (90 min at 60% V02max vs 180 min at 30% V02max). In addition, expired air samples were collected before and after the meal in order to examine the metabolic responses to this meal. Both bouts of exercise attenuated to a similar degree (=30%) the total serum TAG response to the meal compared with the non-exercise trial (5.46±0.63 mmol·J-l·h and 5.53±0.58 mmol-l-l.h at low and moderate intensity respectively vs 8.09±1.09 mmol·J-l·h; p<0.05). Mean respiratory exchange ratio over 6 hours after the meal was lower (p<0.05) in both exercise trials than in the control trial indicating an enhanced fat oxidation during the observational period. All the above three studies were conducted in young adults. The aim of the last study was two-fold (i) to examine whether a bout of moderate intensity walking (60% V02max) would influence the lipaemic and metabolic responses to a fat meal in middle-aged women, as already shown for young adults and (ii) to test the hypothesis that this effect would be greater in trained individuals, by comparing these responses between a trained (n=9) and an untrained (n=13) group. Walking attenuated the total postprandial TAG response to the meal compared to the control trial in both trained (4.9±O.3 mmol·j-1·h vs 7.0±O.S mmol·j-1·h; p<O.OS) and untrained (7.0±O.8 mmol·j-1·h vs 8.4±O.8 mmol·P·h; p<O.OS) women groups. The TAG response to the meal was not significantly different between the two groups in the control trial but it was lower (p<O.OS) in the trained compared to the untrained group 16 hours after the exercise trial. In both groups walking enhanced fat oxidation and decreased fat storage during the postprandial period to a similar degree. The studies described in this thesis have shown that, in young adults and in middle-aged women, one prolonged bout of walking reduces the magnitude of postprandial lipaemia during the recovery period. This effect appears to be dependent on the energy expended during exercise, rather than on its intensity per se, and may be greater in the trained state.

No description available.

No description available.