Biomedical subjects

C J Gore

Publications and source records attributed to C J Gore.

At least 37 records · Page 2Linked to original sources

PubMed2000

Beta-hydroxy beta-methylbutyrate (HMB) supplementation does not influence the urinary testosterone: epitestosterone ratio in healthy males.

Six healthy, recreationally active, males undertook two weeks supplementation with beta-Hydroxy beta-Methylbutyrate (HMB). Supplementation was in capsule form with 3 g consumed each day in three even doses of 1 g at main meals. Mid stream urine samples were collected prior to, as well as, after one and two weeks of supplementation and subsequently analysed for testosterone and epitestosterone. The testosterone: epitestosterone ratio was not affected by 2 weeks of HMB supplementation (mean +/- SD baseline 1.02 +/- 0.68; week one 0.98 +/- 0.61; week two 0.92 +/- 0.62). Our results support the claim that supplementation with HMB at the doses recommended will not influence the urinary testosterone: epitestosterone ratio and thus not breach doping policies of the International Olympic Committee for exogenous testosterone or precursor administration.

Adult↗

PubMed2000

The relationship between body mass index and waist circumference: implications for estimates of the population prevalence of overweight.

OBJECTIVE: Body mass index (BMI) based on self-reported height and weight is a systematically biased, but acceptable measure of adiposity and is commonly used in population surveys. Recent studies indicate that abdominal obesity is more strongly associated with obesity-related health problems than is adiposity measured by BMI. The purpose of this study was to determine the relationships of both measured and self-reported BMI with measured waist circumference in a randomly selected sample of Australian adults. DESIGN: Cross-sectional survey with self-reported and laboratory-based measures of adiposity. SUBJECTS: 1140 randomly-selected Australian adults aged 18-78 y resident in the city of Adelaide, South Australia. MEASUREMENTS: Data on self-reported and measured height and weight as well as measured waist circumference were drawn from the Pilot Survey of the Fitness of Australians database. The proportion of men and women with acceptable BMI (BMI</=25 kg/m2) and with excess abdominal adiposity (>/=94 cm for men and >/=80 cm for women) was determined. Differences in the prevalence of overweight based on BMI alone or BMI and waist circumference were also determined. RESULTS: Compared with the prevalence based on self-reported BMI alone, the prevalence of overweight among men based on self-reported BMI and waist circumference combined was 2.4%, 5.3%, 19.1% and 7.5% greater for men aged 18-39 y, 40-59 y, 60-78 y and for all men, respectively. Among women, compared with the prevalence based on self-reported BMI alone, the prevalence of overweight based on the combined measures was 9.9%, 24.0%, 33.3% and 20.6% greater for women aged 18-39 y, 40-59 y, 60-78 y and for all women, respectively. CONCLUSIONS: If waist circumference is used as the criterion, then the prevalence of overweight among Australian adults, and probably other Caucasian populations, may be significantly greater than indicated by surveys relying on self-reported height and weight. The development of valid self-reported measures of waist circumference for use in population surveys may allow more accurate epidemiological monitoring of overweight and obesity.

Abdomen↗

PubMed2000

Reticulocyte parameters as potential discriminators of recombinant human erythropoietin abuse in elite athletes.

This study investigated using reticulocyte (retic) parameters as indirect markers of human recombinant erythropoietin (r-HuEPO) abuse in elite athletes. Absolute reticulocyte count (# retic), the per cell haemoglobin content of reticulocytes (CHr), reticulocyte haemoglobin mass per litre of blood (RetHb) and red blood cell:reticulocyte haemoglobin (RBCHb:RetHb) ratio were assessed using flow cytometry. Venous blood was drawn from 155 elite athletes from six sports during regular training to establish reference ranges (95% confidence interval) for these parameters. The reference ranges were compared with those of a non-athletic population (n = 23), four groups of athletes (n = 24) before and after exposure to simulated altitudes (2,500-3,000 m for 11-23 nights), two groups of elite cyclists (n = 13) before and after four weeks of training at natural altitude (1,780 and 2,690 m), and with those of non-athletic subjects from a separate study (n =24) before and 1-2 days after they were injected with 1,200 U x kg(-1) r-HuEPO over a 9-10 day period. Generally the changes induced by r-HuEPO injection exceeded by approximately 100% the magnitude of the changes associated with natural altitude exposure. Simulated altitude exposure did not significantly alter the reticulocyte parameters. From the sample of 155 non-users and 24 r-HuEPO users, the population mean and variance, as well as the 95% confidence limits for the population mean and population variance, were estimated. Relative to arbitrarily chosen cut-off levels, the confidence limits for the rate of true positives and rate of true negatives were also calculated. Based on the lowest rate of false positives and highest rate of true positives, the best discriminator between r-HuEPO users and non-users was # retic, marginally superior to RBCHb: RetHb ratio and RetHb. At a cut-off for # retic of 221 x 10(9)x L(-1) we could be 95% sure that we would find no more than 7 false positives in every 100,000 tests. We would expect to pick up 51.8% of users, and could be 95% sure of picking up at least 38% of current or recent users. This result highlights the potential power of retic parameters for detecting r-HuEPO abuse among athletes. However, the efficacy of these cut-offs for detecting r-HuEPO abuse is unknown if an athlete is a chronic user or stops using r-HuEPO several weeks before being tested.

Bicycling↗

PubMed2000

Skinfold thickness varies directly with spring coefficient and inversely with jaw pressure.

PURPOSE: The main aims of this study were to: 1) determine whether heavy use of Harpenden calipers caused deterioration of the spring coefficient (force per unit length), 2) to quantify the change in skinfold thickness per unit change in jaw closing (downscale) pressure, and 3) to develop a calibration range for these calipers. METHODS: Part a) The change in spring force per unit length after at least 100,000 cycles of opening and closing five different springs was measured on a load cell. Part b) The dynamic downscale jaw pressure exerted by six pairs of Harpenden springs was measured on one caliper. Two were new pairs of springs (N1 and N2), two were 25-yr-old springs (O1 and O2), and two pairs (S1 and S2) had been used for less 1 yr. The six spring pairs were used to measure skinfold thicknesses at nine sites, in triplicate, on 20 subjects with the order of springs randomized and counterbalanced. Part c) The downscale jaw pressure of 78 Harpenden calipers was measured at eight jaw gaps. RESULTS: Part a) The springs did not change their characteristics after >100,000 cycles. Part b) At each skinfold site, the lowest thickness was recorded for S2 which exerted the highest jaw pressure (9.04 g x mm(-2)) and conversely the highest thickness was for N1 which exerted the lowest jaw pressure (8.02 g x mm(-2)). Increasing the downscale jaw closing pressure from 8.0 to 9.0 g x mm(-2) reduced a skinfold thickness by approximately 10%. Part c) The mean downscale jaw pressure was 7.82 +/- 0.25 g x mm(-2). CONCLUSIONS: In summary, it is suggested that if accurate skinfold measures between different Harpenden calipers are required, the downscale jaw pressure should be in the range of 7.40-7.82 and 7.85-8.21 g x mm(-2), at jaw gaps of 5 and 40 mm, respectively. These jaw pressures can be achieved by servicing the caliper pivot and indicator gauge to minimize frictional losses, adjusting the caliper jaw alignment, and by selecting springs that have a spring coefficient in the range 1.10-1.15 N x mm(-1).

Calibration↗

PubMed2000

Impaired interval exercise responses in elite female cyclists at moderate simulated altitude.

The effect of hypoxia on the response to interval exercise was determined in eight elite female cyclists during two interval sessions: a sustained 3 x 10-min endurance set (5-min recovery) and a repeat sprint session comprising three sets of 6 x 15-s sprints (work-to-relief ratios were 1:3, 1:2, and 1:1 for the 1st, 2nd, and 3rd sets, respectively, with 3 min between each set). During exercise, cyclists selected their maximum power output and breathed either atmospheric air (normoxia, 20.93% O(2)) or a hypoxic gas mix (hypoxia, 17.42% O(2)). Power output was lower in hypoxia vs. normoxia throughout the endurance set (244+/-18 vs. 226+/-17, 234+/-18 vs. 221+/-25, and 235+/-18 vs. 221+/-25 W for 1st, 2nd, and 3rd sets, respectively; P< 0.05) but was lower only in the latter stages of the second and third sets of the sprints (452+/-56 vs. 429+/-49 and 403+/-54 vs. 373+/- 43 W, respectively; P<0.05). Hypoxia lowered blood O(2) saturation during the endurance set (92.9+/-2.9 vs. 95.4+/-1.5%; P<0.05) but not during repeat sprints. We conclude that, when elite cyclists select their maximum exercise intensity, both sustained (10 min) and short-term (15 s) power are impaired during hypoxia, which simulated moderate ( approximately 2,100 m) altitude.

Acids↗

PubMed2000

A novel method utilising markers of altered erythropoiesis for the detection of recombinant human erythropoietin abuse in athletes.

BACKGROUND AND OBJECTIVE: The use of recombinant human erythropoietin (r-HuEPO) to enhance athletic performance is prohibited. Existing tests cannot readily differentiate between exogenous and endogenous EPO. Therefore the aim of our study was to investigate possible indirect detection of r-HuEPO use via blood markers of altered erythropoiesis. DESIGN AND METHODS: Twenty-seven recreational athletes were assigned to three groups prior to a 25 day drug administration phase, with the following protocols: EPO+IM group (n = 10), 50 Ukg(-1) r-HuEPO at a frequency of 3wk(-1), 100 mg intramuscular (IM) iron 1wk(-1) and a sham iron tablet daily; EPO+OR group (n = 8), 50 U.kg(-1) r-HuEPO 3wk(-1), sham iron injection 1wk(-1) and 105 mg of oral elemental iron daily; placebo group (n = 9), sham r-HuEPO injections 3wk(-1), sham iron injections 1wk(-1) and sham iron tablets daily. Each group was monitored during and for 4 weeks after drug administration. RESULTS: Models incorporating combinations of the variables reticulocyte hematocrit (RetHct), serum EPO, soluble transferrin receptor, hematocrit (Hct) and % macrocytes were analyzed by logistic regression. One model (ON-model) repeatedly identified 94-100% of r-HuEPO group members during the final 2 wk of the r-HuEPO administration phase. One false positive was recorded from a possible 189. Another model (OFF-model) incorporating RetHct, EPO and Hct was applied during the wash-out phase and, during the period of 12-21 days after the last r-HuEPO injection, it repeatedly identified 67-72% of recent users with no false positives. INTERPRETATION AND CONCLUSIONS: Multiple indirect hematologic and biochemical markers used simultaneously are potentially effective for identifying current or recent users of r-HuEPO.

Adult↗

PubMed1999

Exercise-induced hypoxaemia in highly trained cyclists at 40% peak oxygen uptake.

A group of 15 competitive male cyclists [mean peak oxygen uptake, VO2peak 68.5 (SEM 1.5 ml x kg(-1) x min(-1))] exercised on a cycle ergometer in a protocol which began at an intensity of 150 W and was increased by 25 W every 2 min until the subject was exhausted. Blood samples were taken from the radial artery at the end of each exercise intensity to determine the partial pressures of blood gases and oxyhaemoglobin saturation (SaO2), with all values corrected for rectal temperature. The SaO2 was also monitored continuously by ear oximetry. A significant decrease in the partial pressure of oxygen in arterial blood (PaO2) was seen at the first exercise intensity (150 W, about 40% VO2peak). A further significant decrease in PaO2 occurred at 200 W, whereafter it remained stable but still significantly below the values at rest, with the lowest value being measured at 350 W [87.0 (SEM 1.9) mmHg]. The partial pressure of carbon dioxide in arterial blood (PaCO2) was unchanged up to an exercise intensity of 250 W whereafter it exhibited a significant downward trend to reach its lowest value at an exercise intensity of 375 W [34.5 (SEM 0.5) mmHg]. During both the first (150 W) and final exercise intensities (VO2peak) PaO2 was correlated significantly with both partial pressure of oxygen in alveolar gas (P(A)O2, r = 0.81 and r = 0.70, respectively) and alveolar-arterial difference in oxygen partial pressure (P(A-a)O2, r = 0.63 and r = 0.86, respectively) but not with PaCO2. At VO2peak PaO2 was significantly correlated with the ventilatory equivalents for both oxygen uptake and carbon dioxide output (r = 0.58 and r = 0.53, respectively). When both P(A)O2 and P(A-a)O2 were combined in a multiple linear regression model, at least 95% of the variance in PaO2 could be explained at both 150 W and VO2peak. A significant downward trend in SaO2 was seen with increasing exercise intensity with the lowest value at 375 W [94.6 (SEM 0.3)%]. Oximetry estimates of SaO2 were significantly higher than blood measurements at all times throughout exercise and no significant decrease from rest was seen until 350 W. The significant correlations between PaO2 and P(A)O2 with the first exercise intensity and at VO2peak led to the conclusion that inadequate hyperventilation is a major contributor to exercise-induced hypoxaemia.

Adult↗

PubMed1999

Skin-prick blood samples are reliable for estimating Hb mass with the CO-dilution technique.

Investigation of the impact of environmental stimuli such as altitude exposure on hemoglobin mass currently rely on invasive techniques that require venous blood sampling. This study assessed the feasibility of lancet skin pricks as an alternative to venepuncture to estimate hemoglobin mass with the carbon monoxide (CO) dilution technique, with the intent of making the technique accessible to technicians without phlebotomy training. Sixteen healthy volunteers rebreathed CO via a small-volume rebreathing apparatus. Blood was sampled simultaneously with a glass syringe (VEN) from a superficial forearm vein and with a capillary tube from either a lanced fingertip or earlobe (CAP). As a control, VEN blood was then aliquoted into capillary tubes (CONTROL-CAP). Samples were assayed for carboxy-hemoglobin (HbCO) using a diode-array spectrophotometer. Mean %HbCO was higher in CAP than VEN (bias 0.3+/-0.2%HbCO, p < 0.01), but VEN and CONTROL-CAP were not different (p = 0.55). Compared to VEN, Hb mass derived from CAP samples was overestimated by 1.7% (15+/-22 g Hb, p = 0.01). CAP samples to estimate Hb mass demonstrated a technical error of measurement of 2.7%, which is comparable to the 1.9% reported previously with VEN samples. We conclude that using CAP samples gives a reliable measure of %HbCO, and will make the estimation of Hb mass with the CO-technique accessible to technicians without phlebotomy training.

Administration, Inhalation↗

PubMed1999

Effects of a 12-day "live high, train low" camp on reticulocyte production and haemoglobin mass in elite female road cyclists.

The aim of this study was to document the effect of "living high, training low" on the red blood cell production of elite female cyclists. Six members of the Australian National Women's road cycling squad slept for 12 nights at a simulated altitude of 2650 m in normobaric hypoxia (HIGH), while 6 team-mates slept at an altitude of 600 m (CONTROL). HIGH and CONTROL subjects trained and raced as a group throughout the 70-day study. Baseline levels of reticulocyte parameters sensitive to changes in erythropoeisis were measured 21 days and 1 day prior to sleeping in hypoxia (D1 and D20, respectively). These measures were repeated after 7 nights (D27) and 12 nights (D34) of simulated altitude exposure, and again 15 days (D48) and 33 days (D67) after leaving the altitude house. There was no increase in reticulocyte production, nor any change in reticulocyte parameters in either the HIGH or CONTROL groups. This lack of haematological response was substantiated by total haemoglobin mass measures (CO-rebreathing), which did not change when measured on D1, D20, D34 or D67. We conclude that in elite female road cyclists, 12 nights of exposure to normobaric hypoxia (2650 m) is not sufficient to either stimulate reticulocyte production or increase haemoglobin mass.

Adult↗

PubMed1999

"Live high, train low" does not change the total haemoglobin mass of male endurance athletes sleeping at a simulated altitude of 3000 m for 23 nights.

The purpose of this study was to document the effect of 23 days of "live high, train low" on the haemoglobin mass of endurance athletes. Thirteen male subjects from either cycling, triathlon or cross-country skiing backgrounds participated in the study. Six subjects (HIGH) spent 8-10 h per night in a "nitrogen house" at a simulated altitude of 3000 m in normobaric hypoxia, whilst control subjects slept at near sea level (CONTROL, n = 7). Athletes logged their daily training sessions, which were conducted at 600 m. Total haemoglobin mass (as measured using the CO-rebreathing technique) did not change when measured before (D1 or D2) and after (D28) 23 nights of hypoxic exposure [HIGH 990 (127) vs 972 (97) g and CONTROL 1042 (133) vs 1033 (138) g, before and after simulated altitude exposure, respectively]. Nor was there any difference in the substantial array of reticulocyte parameters measured using automated flow cytometry prior to commencing the study (D1), after 6 (D10) and 15 (D19) nights of simulated altitude, or 1 day after leaving the nitrogen house (D28) when HIGH and CONTROL groups were compared. We conclude that red blood cell production is not stimulated in male endurance athletes who spend 23 nights at a simulated altitude of 3000 m.

Adult↗

PubMed1999

Utility of pwc75% as an estimate of aerobic power in epidemiological and population-based studies.

PURPOSE: Studies of physical activity often assess physical work capacity (pwc) and this is usually achieved with extrapolated estimates of maximal aerobic power (VO2max). However, extrapolation beyond the measured values may be problematic, particularly for older subjects. On a population basis, interpolated measures of pwc may provide the same information and avoid the errors associated with extrapolated measures. METHODS: This study assessed extrapolated (pwc at 150 and 170 beats x min(-1) heart rate (HR) and estimated VO2max) and interpolated (pwc at 75% of maximum HR: pwc75%) measures of pwc in a population sample of 1043 men and women aged 18-78 yr. Each measure was assessed to determine whether it showed the key characteristics of measured VO2max: a decrease with age and an increase with reported physical activity. RESULTS: Both pwc150 and pwc170 did not decline with age, estimated VO2max (est.VO2max) exhibited a spurious plateau for older age groups, while pwc75% declined approximately 9% per decade of age. All four pwc measures detected a significant difference (approximately 10-15%) between inactive and active groups classified according to a questionnaire of leisure time physical activity. CONCLUSIONS: Although the pwc75% test requires direct validation, these results suggest that it may be a useful submaximal exercise measure for epidemiological studies of aerobic power.

Adult↗

PubMed1999

Pulmonary gas exchange during exercise in highly trained cyclists with arterial hypoxemia.

The causes of exercise-induced hypoxemia (EIH) remain unclear. We studied the mechanisms of EIH in highly trained cyclists. Five subjects had no significant change from resting arterial PO(2) (Pa(O(2)); 92.1 +/- 2.6 Torr) during maximal exercise (C), and seven subjects (E) had a >10-Torr reduction in Pa(O(2)) (81.7 +/- 4.5 Torr). Later, they were studied at rest and during various exercise intensities by using the multiple inert gas elimination technique in normoxia and hypoxia (13.2% O(2)). During normoxia at 90% peak O(2) consumption, Pa(O(2)) was lower in E compared with C (87 +/- 4 vs. 97 +/- 6 Torr, P < 0.001) and alveolar-to-arterial O(2) tension difference (A-aDO(2)) was greater (33 +/- 4 vs. 23 +/- 1 Torr, P < 0. 001). Diffusion limitation accounted for 23 (E) and 13 Torr (C) of the A-aDO(2) (P < 0.01). There were no significant differences between groups in arterial PCO(2) (Pa(CO(2))) or ventilation-perfusion (VA/Q) inequality as measured by the log SD of the perfusion distribution (logSD(Q)). Stepwise multiple linear regression revealed that lung O(2) diffusing capacity (DL(O(2))), logSD(Q), and Pa(CO(2)) each accounted for approximately 30% of the variance in Pa(O(2)) (r = 0.95, P < 0.001). These data suggest that EIH has a multifactorial etiology related to DL(O(2)), VA/Q inequality, and ventilation.

Adult↗

PubMed1998

Altitude training at 2690m does not increase total haemoglobin mass or sea level VO2max in world champion track cyclists.

Haemoglobin mass (Hb mass), maximum oxygen consumption (VO2max), simulated 4000 m individual pursuit cycling performance (IP4000), and haematological markers of red blood cell (RBC) turnover were measured in 8 male cyclists before and after (A) 31 d of altitude training at 2690 m. The dependent variables were measured serially after altitude on d A3-4, A8-9 and A20-21. There was no significant change in Hb mass over the course of the study and VO2max at d A9 was significantly lower than the baseline value (79.3 +/- 0.7 versus 81.4 +/- 0.6 ml x kg(-1) x min(-1), respectively). No increase in Hb mass or VO2max was probably due to initial values being close to the natural physiological limit with little scope for further change. When the IP4000 was analysed as a function of the best score on any of the three test days after altitude training there was a 4% improvement that was not reflected in a corresponding change in VO2max or Hb mass. RBC creatine concentration was significantly reduced after altitude training, suggesting a decrease in the average age of the RBC population. However, measurement of reticulocyte number and serum concentrations of erythropoietin, haptoglobin and bilirubin before and after altitude provided no evidence of increased RBC turnover. The data suggest that for these elite cyclists any benefit of altitude training was not from changes in VO2max or Hb mass, although this does not exclude the possibility of improved anaerobic capacity.

Adult↗

PubMed1998

Effects of body composition and fat distribution on ventilatory function in adults.

Clinically, gross obesity is associated with disturbances of ventilatory function, but less severe obesity is not generally thought to have a significant effect on ventilatory function. The purpose of this report was to examine cross-sectional data to determine the effects of body composition and fat distribution on ventilatory function in 1235 adults (621 men and 614 women). Forced vital capacity (FVC) was used as a measure of ventilatory function and was adjusted for age, height, smoking, and bronchial symptoms in separate models for men and women. Body fat and fat-free mass were estimated from skinfold-thickness measurements. Adjusted FVC was not significantly associated with body mass or body mass index, but was negatively associated with percentage body fat in men (P = 0.0003) and women (P = 0.043) and positively associated with fat-free mass in men (P = 0.018) and women (P = 0.0001). Handgrip strength was positively associated with adjusted FVC in both sexes (P < 0.02), suggesting that the effect of fat-free mass may be mediated by muscular strength. Adjusted FVC was negatively associated with subscapular-skinfold thickness in both sexes (P < 0.0003) and with waist circumference (P = 0.01) and waist-to-hip ratio (P = 0.03) in men. Previous reports that considered only body mass index or body mass failed to distinguish the opposing effects of fat-free mass and fat mass on FVC.

Adipose Tissue↗

PubMed1997

Reduced performance of male and female athletes at 580 m altitude.

This study examined the effect of mild hypobaria (MH) on the peak oxygen consumption (VO2peak) and performance of ten trained male athletes [x (SEM); VO2peak = 72.4 (2.2) ml x kg(-1) x min(-1)] and ten trained female athletes [VO2peak = 60.8 (2.1) ml x kg(-1) x min(-1)]. Subjects performed 5-min maximal work tests on a cycle ergometer within a hypobaric chamber at both normobaria (N, 99.33 kPa) and at MH (92.66 kPa), using a counter-balanced design. MH was equivalent to 580 m altitude. VO2peak at MH decreased significantly compared with N in both men [-5.9 (0.9)%] and women [-3.7 (1.0)%]. Performance (total kJ) at MH was also reduced significantly in men [-3.6 (0.8)%] and women [-3.8 (1.2)%]. Arterial oxyhaemoglobin saturation (SaO2) at VO2peak was significantly lower at MH compared with N in both men [90.1 (0.6)% versus 92.0 (0.6)%] and women [89.7 (3.1)% versus 92.1 (3.0)%]. While SaO2 at VO2peak was not different between men and women, it was concluded that relative, rather than absolute. VO2peak may be a more appropriate predictor of exercise-induced hypoxaemia. For men and women, it was calculated that 67-76% of the decrease in VO2peak could be accounted for by a decrease in O2 delivery, which indicates that reduced O2 tension at mild altitude (580 m) leads to impairment of exercise performance in a maximal work bout lasting approximately 5 min.

Adult↗

PubMed1997

Training-induced increases in sea level VO2max and endurance are not enhanced by acute hypobaric exposure.

The present study used untrained subjects to examine the effect of acute hypobaric exposure during endurance training on subsequent exercise performance at sea level. Two groups, each of nine subjects, completed 5 weeks of endurance training [cycle ergometer exercise for 45 min, three times per week at a heart rate corresponding to 70% of that achieved at the maximal O2 consumption (VO2max) either at sea level or at high altitude] in a hypobaric chamber, under either normobaric [sea level, SL; 750 mmHg (100 kPa) approximately 90 m] or hypobaric [altitude, ALT; 554 mmHg (73.4 kPa) approximately 2500 m] conditions and the changes in SL VO2max, SL endurance time and peak blood lactate during the endurance test compared. While each group showed increases in both SL VO2max (approximately 12%) and SL endurance time (approximately 71%), there were no significant differences between the groups [SL VO2max, mean (SE)-SL group: pre-training = 42.4 (3.5), post-training = 46.1 (3.5) ml.kg-1.min-1, P < 0.005; ALT group: pre-training = 40.8 (2.6), post-training = 47.2 (3.4) ml.kg-1.min-1, P < 0.01; SL endurance time-SL group: pre-training 7.1 (1.5), post-training 11.8 (2.9) min, P < 0.01; ALT group: pre-training = 7.5 (0.6), post-training = 13.3 (1.4) min, P < 0.001]. Peak blood lactate during the endurance test was not altered by either training regimen. It is concluded that acute exposure of untrained subjects to hypobaric hypoxia during endurance training has no synergistic effect on the degree of improvement in either SL VO2max or endurance time.

Adult↗

PubMed1997

VO2max and haemoglobin mass of trained athletes during high intensity training.

The correlation between relative haemoglobin mass (Hb mass, g x kg[-1]) and relative maximal oxygen consumption (VO2max, ml x kg(-1) x min[-1]) in 62 trained athletes (33 male runners, 12 male rowers and 17 female rowers) with national and/ or international competitive experience was examined. The correlation between Hb mass and VO2max was highest for the female rowers (n=17, r=0.92, p<0.0001), lower for the male rowers (n = 12, r=0.79, p < 0.005) and lowest for the male runners (n=33, r=0.48, p = 0.005). These results suggest that, within an athletic sample, Hb mass may be used to estimate potential aerobic power. In a second series of experiments, Hb mass was measured before and after three different training programs in sub-sets of the subjects used in the earlier study. Hb mass did not change following 12 weeks of intense rowing training, 4 weeks of heat training (32 degrees C), or 4 weeks of medium-altitude training (1740 m). The corresponding increases in VO2max were 7.8%, no change and 2.1 %, respectively. These results suggest that heat or altitude training does not increase Hb mass in trained athletes. Previous studies that demonstrate increases in total red cell volume following altitude acclimatization used subjects with only modest aerobic power, whereas the present study used trained subjects. It is concluded that trained athletes with erythrocythemic hypervolemia have limited capability to increase further either total red cell volume or Hb mass.

Acclimatization↗

PubMed1997

Automated VO2max calibrator for open-circuit indirect calorimetry systems.

The complete calibration of indirect calorimetry systems involves simultaneous checks of gas analyzers, volume device, and software, and this requires a machine that can mimic accurately and precisely the ventilation and expired gases of an athlete. While previous calibrators have been built successfully, none have matched the ventilatory flows produced by athletes during high intensity exercise. A calibrator able to simulate high aerobic power (VO2max calibrator) was fabricated and tested against conventional indirect calorimetry systems that use chain-compensated gasometers to measure expired volume (VE systems) and calibrated electronic gas analyzers. The calibrator was also checked against a system that measures inspired volume (VI system) with a turbine ventilometer. The pooled data from both VE and VI systems for predicted VO2 ranging from 2.9 to 7.9 L.min-1 and ventilation ranging from 89 to 246 L.min-1 how that the absolute accuracy (bias) of values measured by conventional indirect calorimetry systems compared with those predicted by the calibrator was excellent. The bias was < 35 mL.min-1 for VO2 and carbon dioxide production, < 0.50 L.min-1 for ventilator (VE BTPS), -0.02% absolute for the percentage of expired O2 and +0.02% absolute for the percentage of expired CO2. Overall, the precision of the measured VO2, VCO2, and VE BTPS was approximately 1%. This VO2max calibrator is a versatile device that can be used for routine calibration of most indirect calorimetry systems that assess the ventilation and aerobic power of athletes.

Blood Gas Analysis↗