The blood acid base and gastrointestinal response to three different forms of sodium citrate encapsulation.

Enterically coated (ENT) or delayed-release (DEL) capsules may lessen gastrointestinal symptoms (GIS) following acute sodium citrate (SC) ingestion, although the effects on blood acid-base balance are undetermined. Fourteen active males ingested 0.4 g.kg-1 body mass (BM) SC, within gelatine (GEL), DEL and ENT capsules or 0.07 g.kg-1 BM sodium chloride control (CON). Blood acid-base balance and GIS were measured for 4 h. Ingestion form had no significant effect on total GIS experienced (GEL: 2 ± 7; DEL: 1 ± 8; ENT: 1 ± 4 AU). Most (7/14) participants experienced zero symptoms throughout. Peak GIS typically emerged ≤100 min post-ingestion, with a similar time to reach peak GIS between ingestion form (GEL: 36 ± 70; DEL: 13 ± 28; ENT: 15 ± 33 AU). Blood [HCO3-] was significantly higher with ENT versus GEL (ENT: 29.0 ± 0.8; GEL: 28.5 ± 1.1 mmol.L-1, P = 0.037). Acute ingestion of a reduced SC dose elicited minimal GIS, producing significant changes in blood [HCO3-] from rest, irrespective of ingestion form (GEL: 6.0 ± 0.9; DEL: 5.1 ± 1.0; ENT: 6.2 ± 0.8 mmol.L-1). The necessity of individualized ingestion strategies is also challenged, with sustained increases in blood [HCO3-] of ≥4 mmol.L-1 for up to 153 min highlighted. If commencing exercise at peak alkalosis augments subsequent performance above starting at a standardized time point where HCO3- is still elevated remains unclear.

High dose Nitrate ingestion does not improve 40 km cycling time trial performance in trained cyclists.

This study evaluated the chronic effects of nitrate (NO3-) ingestion over three days, on 40 km TT performance in 11trained cyclists (VO2max: 60.8 ± 7.4 ml.kg-1.min-1; age: 36 ± 9 years; height: 1.80 ± 0.06 m; body mass: 87.2 ± 12.0 kg). Utilising a double-blind randomised cross-over design, participants completed three 40 km TT on a Velotron® ergometer following the ingestion of either a 140 ml of "BEET It sport®" NO3- shot containing 12.8 mmol or 800 mg of NO3-, a placebo drink or nothing (control). Performance, oxygen consumption (VO2), blood bicarbonate (HCO3-), pH and lactate (BLa) and ratings of perceived exertion (RPE) were measured every 10 km throughout the TT. The present findings show that NO3- ingestion had no effect on TT performance (NO3-: 4098.0 ± 209.8 vs. Placebo: 4161.9 ± 263.3 s, p = 0.296, ES = 0.11), or VO2 (p = 0.253, ES = 0.13). Similarly, blood lactate and RPE were also unaffected by the experimental conditions (p = 0.522, ES = 0.06; p = 0.085, ES = 0.30) respectively. Therefore, these results suggest that a high dose of NO3- over three days has limited efficacy as an ergogenic aid for 40 km TT cycling performance in trained cyclists.

Energy expenditure and fitness response following once weekly hill climbing at low altitude.

This work sought to determine the fitness responses and energy expenditure (EE) following once-weekly hill climbing for 16 weeks on different slopes. A cohort of 98 healthy, sedentary subjects (49 female, 49 male) completed the program at their preferred climbing pace. Body composition, resting metabolic rate (RMR) and VO2max were measured. EE was measured on 4 slopes (11.6°, 19.9°, 14.9°, and 28.6°) at the subjects' preferred speed. In males, weight, body mass index, fat mass significantly decreased (P<0.05), and RMR showed an increasing trend, but the difference was not significant (P=0.051). In females, the muscle mass increased significantly, and fat (%) and fat mass significantly decreased (P<0.05). Absolute and relative of VO2max, ventilation (VE) improved significantly in both sexes (P<0.01). Energy expenditure was similar on different slopes, but shows gender-specific values of approximately 50.4 and 33.6 kJ/min for males and females, respectively. The regression equation of EE (kJ/min)=[1.724×(female=1, and male=2)+(-0.072×age)+0.106×weight+0.024×HR+0.136×slope+1.487×velocity]×4.2. In conclusion, hill climbing at a subjects' preferred velocity is a vigorous-intensity physical activity for energy cost and, performed once weekly, enhances cardiorespiratory fitness and reduces fat mass, therefore making it a viable exercise for most people.

The effects of caffeine ingestion on time trial cycling performance.

AIM: The purpose of this work was to determine the effects of caffeine ingestion on cycling time trial (TT) performance in well trained male subjects. METHODS: Eight males, with the following physical characteristics (Mean +/- SD) age 30.2+/-10.1 years, height 180.3+/-7.1 cm, mass 70.4+/-5.1 kg, VO2max 63.6+/-4.4 mL.kg(-1).min(-1) undertook three 1 h TT performances on a VelotronPro cycle ergometer, in a double blind, random fashion. The trials were Control (C), Placebo (Pl) and Caffeine (CAF). The CAF and Pl were given 60 min prior to exercise in a dose of 6 mg.kg(-1) body mass. Prior to ingestion, 60 min post ingestion, and at the end of the TT, subjects gave 10 mL of venous blood which was analysed for lactate, glucose, and free fatty acids. Expired air was collected throughout each test by indirect calorimetry. RESULTS: The cyclists rode significantly further in CAF trial (28.11+/-1.32 km) than they did in the C (26.69+/-1.5 km, P < 0.03) or Pl (27.0+/-1.5 km, P < 0.03) trials. No significant differences were seen between C and Pl trials (P > 0.88). No differences between C and Pl were seen in heart rate data throughout the TT (p > 0.05). The free fatty acid (FFA) concentrations were significantly higher in the CAF trials both post ingestion (P < 0.005) and post exercise (P < 0.0001) than either C or Pl trials. CONCLUSION: We concluded that performance was improved possibly based upon a greater reliance on fat metabolism, as indicated by increased FFA and a lower respiratory exchange ratio (RER).

The effects of a nucleotide supplement on the immune and metabolic response to short term, high intensity exercise performance in trained male subjects.

AIM: The aim of this work was to determine the ergogenic effects of a nucleotide supplement on the metabolic and immune responses to short term high intensity exercise in volunteer, trained, male subjects. METHODS: Thirty moderately trained male subjects were randomly divided into 3 equal sized groups, control (C), placebo (P) or experimental (E). Each subject undertook a 2 min maximal exercise test prior to, and after 60 days, on either a nucleotide (E) or placebo supplement. Prior to exercise testing unstimulated saliva samples and blood samples were taken. Saliva was analysed for cortisol and IgA, while blood was analysed for lactate, lactate dehydrogenase and creatine kinase. RESULTS: The postexercise C value was significantly higher than the pre-exercise concentration (P<0.0001; for C, P, and E). In the postsupplement C analysis, the E postexercise group was significantly lower than either the C (P<0.005) or the P group (P<0.05). In the pre- and postsupplementation periods, the pre-exercise SIgA values were significantly higher than the postexercise values (P<0.0001). However, in the postsupplementation period, the SIgA value in the E group was significantly higher than either the P (P<0.05) or C (P<0.05) groups. There were no significant changes in blood lactate, lactate dehydrogenase, or creatine kinase concentrations post supplementation. CONCLUSIONS: We concluded that a chronically ingested nucleotide supplement blunts the response of the hormones associated with physiological stress.

Criteria and other methodological considerations in the evaluation of time at V.O2max.

AIM: Many previous studies have examined the time limit at which an individual can maintain VO(2max) (T(lim) VO(2max)) during high-intensity continuous and intermittent runs to exhaustion. The main purpose of the present study was to examine the effects of employing different criteria used in previous investigations during T(lim) VO(2max) evaluation. METHODS: Seven moderately trained competitive runners completed 2 running tests to exhaustion, during which metabolic data was obtained from breath-by-breath gas analysis. The 1(st) test was an incremental test to evaluate VO(2max) and the minimal running velocity at which VO(2max) was elicited (v VO(2max)). The 2(nd) test was a continuous single velocity test at v VO(2max) from which the time to attain VO(2max) (TA VO(2max)) and T(lim) VO(2max) were subsequently evaluated. Time at VO(2max) was evaluated employing 6 specific criteria. Intra-individual differences in T(lim) VO(2max) values due to applying the different criteria were analysed using a one-way ANOVA, with significant differences between pairs identified using Tukey's HSD posthoc test. Significance was set at p<0.05. RESULTS: A one-way ANOVA demonstrated that significant differences (F=4.03, p=0.005) existed between T(lim) VO(2max) values generated by employing the six different criteria. CONCLUSIONS: The present study provides support that employing different criteria in the evaluation of T(lim) VO(2max), such as those used in previous investigations, leads to significantly different T(lim) VO(2max) values. However, the practical implications of these measurement differences require further investigation.

Time at or near VO2max during continuous and intermittent running. A review with special reference to considerations for the optimisation of training protocols to elicit the longest time at or near VO2max.

Several authors have suggested that training at or near VO2max (i.e. > or = 95% VO2max) is the most effective training intensity to enhance VO2max and that for highly trained endurance athletes, training at or near VO2max may be necessary to increase it further. Consequently, there is an interest in characterising training protocols that allow the longest time at or near VO2max (T@VO2max). Intermittent running protocols have been found to be more effective than continuous protocols for increasing T@VO2max. Intermittent protocols can be manipulated by altering the warm-up intensity and timing, work and relief interval velocity and duration, amplitude, interval number per set, and the number of sets performed. To increase T@VO2max it is recommended that work interval intensity should generally range between 90% and 105% vVO2max and relief interval intensity between 50% vVO2max and the lactate threshold velocity. Work and relief interval durations should be between 15 and 30 seconds. The warm-up period prior to the intermittent protocol should be about 10 to 15 minutes in duration at 1 or 2 km x h(-1) below the lactate threshold velocity, with no gap between the warm-up and the intermittent protocol. When designing intermittent training protocols for the enhancement of VO2max, the simultaneous enhancement of other physiological performance determinants should also be considered. Further experimental research is required to identify the specific physiological responses and adaptations to various intermittent running protocols that are designed to elicit the longest time at or near VO2max, before recommendations can be given to competitive endurance runners.

The effects of a nucleotide supplement on salivary IgA and cortisol after moderate endurance exercise.

AIM: The aim of this work was to determine the ergogenic effects of a nucleotide supplement on salivary immunoglobulin A (SIgA) and cortisol (C) responses after prolonged endurance cycle exercise. METHODS: Fourteen moderately trained male subjects (mean body mass and VO2max) completed 2 90-min cycle ergometer trials (60% VO2max) prior to and after 60 days of either a nucleotide (E group, n=7) or placebo (P group, n=7) supplement. Each of the subjects provided an unstimulated saliva sample prior to and following the exercise for determination of SIgA and C. RESULTS: SIgA was significantly lower after exercise trials in both E and P groups (P<0.0001) prior to as well as after the supplementation period. However, SIgA was significantly higher (P<0.01) in the E group than the P group after supplementation. There were no significant (P>0.11) differences in pre-exercise C level. Postexercise C concentrations were significantly (P<0.001) higher than pre-exercise levels in both groups of subjects. However, after the supplementation period, C concentration was significantly (P<0.0001) lower after exercise in E compared to P. CONCLUSIONS: This work suggests that a nucleotide supplement, given chronically may offset the hormonal response associated with demanding endurance exercise.

The relationship between the lactate turnpoint and the time at VO2max during a constant velocity run to exhaustion.

The present investigation examined the relationship between the running velocity at the lactate turnpoint (vLTP) and the time at which VO2max can be sustained (TVO2max) during a continuous run to exhaustion at the minimal running velocity that elicits VO2max (vVO2max). Seven moderately-trained endurance runners undertook three tests on a treadmill. The first test was to determine vVO2max; the second to determine the time to exhaustion during a constant velocity run at vVO2max (Tlim vVO2max) and TVO2max; and the third to determine the vLTP. Pearson's correlation coefficient was used to determine the association between the vLTP (%vVO2max; i.e. the relative vLTP) and TVO2max, and between other selected physiological variables. Correlations between the relative vLTP and TVO2max, expressed as a percentage of T(lim vVO2max (the relative TVO2max; r=0.82), and between TVO2max and Tlim vVO2max (r=0.89), were significant at the p<0.05 level. All other correlations between selected measured physiological variables were found to be statistically insignificant. The main finding of this present study is that the relative vLTP demonstrated a significant positive correlation with the relative TVO2max. The physiological mechanism by which the lactate turnpoint may influence the relative TVO2max has not been elucidated, but may be due to a combination of decreasing the time to attain VO2max and increasing Tlim vVO2max. The present investigation has demonstrated that the lactate turnpoint may influence the relative time at which VO2max can be sustained during a continuous run to exhaustion at vVO2max, although further research is required to substantiate these findings.

Portable gas analyser Cosmed K4b2 compared to a laboratory based mass spectrometer system.

AIM: The purpose of this study was to systematically test the accuracy of an automated, portable, gas analysis system, the Cosmed K4b2 with a laboratory based mass spectrometer system, the Morgan EX670 across a number of gas and ventilation parameters. METHODS: Eight subjects (mean+/-SE) age, 23.7+/-1.1 y, height, 1.78+/-0.01 m, mass, 74.4+/-2.1 kg performed a V.O2max test and a submaximal exercise test at 150, 200, 250 and 300 Watts (W), on an SRM cycle ergometer. The Morgan EX670 system and the K4b2 were randomly connected in series, using the same breath for the calculation of gas and ventilatory parameters. RESULTS: The K4b2 system reads significantly higher than the Morgan EX 670 for both VO2 and V.CO2 at 250 (VO2/V.CO2: p<0.05, p<0.002), and 300 W (VO2/V.CO2: p<0.002, p<0.005). Unsystematic bias between the 2 analysers varies between 1% and 16% and systematic bias between 3% and 8%. CONCLUSION: There are some significant unsystematic and systematic differences between these 2 systems and laboratories should endeavour to utilise either one or the other piece of equipment to test their subjects.

A comparison of the lactate Pro, Accusport, Analox GM7 and Kodak Ektachem lactate analysers in normal, hot and humid conditions.

This study aimed to compare the performance of a new portable lactate analyser against other standard laboratory methods in three conditions, normal (20 +/- 1.3 degrees C; 40 +/- 5 % RH), hot (40 +/- 2.5 degrees C; 40 +/- 5 % RH), and humid (20 +/- 1.1 degrees C; 82 +/- 6 % RH) conditions. Seven healthy males, ([Mean +/- SE]: age, 26.3 +/- 1.3 yr; height, 177.7 +/- 1.6 cm; weight, 77.4 +/- 0.9 kg, .VO(2)max, 56.1 +/- 1.9 ml x kg x min(-1)) undertook a maximal cycle ergometry test to exhaustion in the three conditions. Blood was taken every 3 min at the end of each stage and was analysed using the Lactate Pro LT-1710, the Accusport, the Analox GM7 and the Kodak Ektachem systems. The MANOVA (Analyser Type x Condition x Workload) indicated no interaction effect (F(42,660), = 0.45, p > 0.99, Power = 0.53). The data across all workloads indicated that the machines measured significantly differently to each other (F(4,743) = 14.652, p < 0.0001, Power = 1.00). The data were moderately to highly correlated. We conclude that the Lactate Pro is a simple and effective measurement device for taking blood lactate in a field or laboratory setting. However, we would caution against using this machine to compare data from other machines.

Acute versus chronic sodium bicarbonate ingestion and anaerobic work and power output.

BACKGROUND: The aim of this study was to compare and contrast the effects of acute versus chronic sodium bicarbonate ingestion. PARTICIPANTS: Eight male, (mean+/-SE): age, 20.8+/-0.4 yrs; height, 179.6+/-0.6 cm; body mass, 79.4+/-0.85 kg, Sigma7skf, 48.6+/-4.8 mm, VO2max=55.9+/-0.8 ml x kg(-1) x min(-1)) volunteer subjects, ingested NaHCO3 in either a dose of 0.5 g x kg(-1) body mass acutely or the same dose daily over a period of six days in order to determine whether there were any differences in performance of 90 sec maximal cycling ergometry. INTERVENTION: After subjects undertook an initial control (C) test session, all were then randomly assigned to one of two groups, acute or chronic NaHCO3 ingestion. Subjects in the acute ingestion (AI) group completed their supplemented test on day one, and then on the following day. Chronic ingestion (CI) subjects completed the test after one day of chronic ingestion as well as following six days of bicarbonate ingestion. Following ten days rest, subjects repeated the protocol in the opposite group. MEASURES: Blood samples were taken pre- and postingestion, daily, and pre- and postexercise and were analysed for, pH, Base excess (BE), HCO3-, PO2, PCO2, Na+, K+, Cl-, and lactate. RESULTS: Both the chronic (CI) and acute ingestion (AI) groups were significantly different to the control (C) value (p<0.001 and p<0.05, respectively). CONCLUSIONS: We would suggest using chronic ingestion as a means to improve high intensity work rather than the acute ingestion of sodium bicarbonate. The ingestion of sodium bicarbonate, over a period of six days, significantly improved work output two days after bicarbonate ingestion ceased.

A comparison of two different shuttle run tests for the estimation of VO2max.

The aims of this experiment were twofold. The first was to determine whether there was a significant difference between two types of 20-m shuttle run test used to estimate VO2max, these being the Canadian version (CT) and the European versione (ET). The second aim was to determine which of the two tests best estimated direct VO2 measurement in our laboratory. To accomplish the first aim, 500 schoolchildren aged 12 to 16 years were randomly chosen from schools within Tasmania to undertake the two tests within seven days of each other. On the day of testing the children were assigned to one of the two tests and had no knowledge as to which test was being undertaken. Half of the children underwent the CT test first while the other half undertook the ET test first. Seven days after the first test was completed the appropriate second test was undertaken. The instructions to each child centred around the necessity to complete as many shuttles as possible staying in time with a pre-recorded signal. A relationship between the two sets of shuttle run data indicated that there was a significant correlation between the ET and CT, r = 0.834 (p < 0.0001). A Student's "t" test revealed that when the estimates of VO2max were compared however, there was a significant difference between the two tests (p < 0.0001). The ET estimated (Mean +/- SEM) VO2max at 34.9 +/- 0.45 ml.kg-1.min-1 whereas the CT estimated VO2max at 43.3 +/- 0.40 ml.kg-1.min-1. When this data was correlated, the co-efficient dropped to r = 0.761 which was still significant (p < 0.001). In order to accomplish the second aim, fifty children were chosen at random to undertake a VO2max test (DM) which was conducted via standard open circuit spirometry using a Quinton Metabolic Cart (QMC). The highest correlation was DM:ET being r = 0.93 whereas DM:CT was r = 0.87, both being significant at p < 0.001. When the data was compared there was a significant (p < 0.05) difference between DM and ET. DM measured VO2max as 37.6 +/- 0.37 ml.kg-1.min-1 whereas ET underestimated DM and measured VO2max at 34.7 +/- 0.56 ml.kg-1.min-1. The CT (41.9 +/- 0.62 ml.kg-1.min-1) over estimated DM by 11.4% however, the difference here also being significant (p < 0.01). This results of this study would suggest that teachers and coaches should use either one test or the other in the estimation of VO2max as the two tests differ significantly in their estimation. Of these two test versions, the ET underestimates direct VO2max measurement but is more accurate than the CT, so we feel this is the test of choice.

Critical power may be determined from two tests in elite kayakers.

Eight highly trained male kayakers were studied in an attempt to examine whether critical power (CP), based upon four tests, could be determined from a combination of any two tests. The mean age of the subjects was 26.3 (SEM 3.8) years, mean height was 180.9 (SEM 5.1) cm, and mean body mass was 81.7 (SEM 8.3) kg. Four exercise sessions of 90 s, 240 s, 600 s, and 1200 s duration were used. For each subject the total work output was plotted against the duration of each test, the CP being obtained from the line of best fit. The CP obtained from this relationship was then compared to the CP derived from six combinations (90/240, 90/600, 90/1200, 240/600, 240/1200 and 600 00 s) of various performance times. A repeated measures analysis of variance found a significant difference between the exercise intensity obtained from the line of best fit and that obtained for the combination of exercise times of 90/240 s, F(7,1) = 11.12 (P < 0.05). No other significant differences were found between the CP from the line of best fit and that from any of the other possible exercise combinations. This would suggest that any combination of time intervals except 90/240 s may be used to determine the CP of elite kayakers.

The effects of intensity of exercise on excess postexercise oxygen consumption and energy expenditure in moderately trained men and women.

This experiment investigated the effects of intensity of exercise on excess postexercise oxygen consumption (EPOC) in eight trained men and eight women. Three exercise intensities were employed 40%, 50%, and 70% of the predetermined maximal oxygen consumption (VO2max). All ventilation measured was undertaken with a standard, calibrated, open circuit spirometry system. No differences in the 40%, 50% and 70% VO2max trials were observed among resting levels of oxygen consumption (VO2) for either the men or the women. The men had significantly higher resting VO2 values being 0.31 (SEM 0.01) l.min-1 than did the women, 0.26 (SEM 0.01) l.min-1 (P < 0.05). The results indicated that there were highly significant EPOC for both the men and the women during the 3-h postexercise period when compared with resting levels and that these were dependent upon the exercise intensity employed. The duration of EPOC differed between the men and the women but increased with exercise intensity: for the men 40%--31.2 min; 50%--42.1 min; and 70%--47.6 min and for the women, 40%--26.9 min; 50%--35.6 min; and 70%--39.1 min. The highest EPOC, in terms of both time and energy utilised was at 70% VO2max. The regression equation for the men, where y = O2 in litres, and x = exercise intensity as a percentage of maximum was y = 0.380x + 1.9 (r2 = 0.968) and for the women is y = 0.374x - 0.857 (r2 = 0.825).(ABSTRACT TRUNCATED AT 250 WORDS)

Spur cell anemia (acanthocytosis) complicating idiopathic hemochromatosis.

A 65-year-old male developed a rapidly progressive disease characterized by severe hemolysis, with spur cells (acanthocytes) and liver disease. Autopsy findings were consistent with a diagnosis of idiopathic hemochromatosis. Investigation of the patient's family uncovered four out of five first degree relatives with significantly raised serum ferritin levels. A sister had biopsy proven hemochromatosis. Spur cell anemia is a recognized, though rare, complication of alcoholic liver disease and indeed the patient had a regular alcohol intake of up to 50 g daily. Although the alcohol intake could have contributed to the formation of spur cells, the possible association with hemochromatosis should be considered. A diagnosis of hemochromatosis has important implications for family members.

Induced metabolic alkalosis and its effects on 400-m racing time.

Six trained male athletes who competed regularly in 400 metre races, were studied under control, alkalotic (NaHCO3) and placebo (CaCO3) conditions to study the effect of induced metabolic alkalosis on 400 m racing time. Pre and post exercise blood samples in the three conditions were analysed for pH, bicarbonate and base excess. Following ingestion of NaHCO3, pre-exercise pH, bicarbonate and base excess levels were significantly higher than either control or placebo conditions. In the alkalotic condition the subjects ran significantly (p less than 0.005) faster (1.52 s) than either the control of placebo conditions. The post-exercise pH, bicarbonate and base excess levels were all lower in the alkalotic condition than in the others. The results suggest that NaH-CO3 can be used as an effective ergogenic aid and support the speculation that the increased extracellular buffering afforded by NaHCO3 ingestion facilitated efflux of H+ from the working tissues, thus decreasing intracellular pH and hence offsetting fatigue.