NOS3 Gene Polymorphisms and Exercise Hemodynamics in Postmenopausal Women

We tested whether the G894T and T-786C NOS3 polymorphisms were associated with exercise cardiovascular (CV) hemodynamics in sedentary, physically active, and endurance-trained postmenopausal women. CV hemodynamic parameters including heart rate (HR), systolic (SBP) and diastolic (DBP) blood pressures and cardiac output (Q), as determined by acetylene rebreathing, stroke volume (SV), arteriovenous oxygen difference (a-vO2 diff), and total peripheral resistance (TPR) were measured during submaximal (40, 60, 80 %) and maximal (approximately 100 % VO2max) exercise. NOS3 G894T genotype was not significantly associated, either independently or interactively with habitual physical activity (PA) level, with SBP, Q, TPR, or a-vO2 diff during submaximal or maximal exercise. However, NOS3 894T non-carriers had a higher submaximal exercise HR than NOS3 894T allele carriers (120 +/- 2 vs. 112 +/- 2 beats/min, p = 0.007). NOS3 894T allele carriers had a higher SV than 894T non-carriers (78 +/- 2 vs. 72 +/- 2 ml/beat, p = 0.03) during submaximal exercise. NOS3 894T non-carriers also had a higher maximal exercise HR averaged across habitual PA groups than T allele carrier women (165 +/- 2 vs. 158 +/- 2 beats/min, p = 0.04). NOS3 894T allele carriers also tended to have a higher SV during maximal exercise than 894T non-carriers (70 +/- 2 vs. 64 +/- 2 ml/beat, p = 0.08). NOS3 T-786C genotype was not significantly associated, either independently or interactively, with any of the CV hemodynamic measures during submaximal or maximal exercise. These results suggest an association of NOS3 G894T genotype with submaximal and maximal exercise CV hemodynamic responses, especially HR, in postmenopausal women.

Physical activity, hormone replacement therapy and plasma lipoprotein-lipid levels in postmenopausal women

We assessed the cross-sectional associations between hormone replacement therapy (HRT), habitual physical activity levels and plasma lipoprotein-lipid levels in postmenopausal women. Sedentary (n = 19), active nonathlete (n = 20) and endurance-trained (n = 21) postmenopausal women, with half of each group on and half not on HRT, underwent assessments of plasma lipids, VO2max, body composition, diet and common genetic variants. The groups' physical characteristics were generally similar though body weight was higher in the active nonathletes, and body fat was lower and VO2max higher in the athletes. HRT was associated with beneficial total cholesterol, LDL-C and HDL-C levels in sedentary and active nonathlete women. Plasma lipoprotein-lipid profiles were similar in women athletes on and not on HRT, with their profiles being only slightly better than sedentary and physically-active women on HRT. After controlling for HRT status, VO2max was correlated with total cholesterol (r = -0.51, p = 0.0001), LDL-C (r = -0.52, p = 0.0001), HDL-C (r = 0.25, p = 0.055), HDL 2 -C (r = 0.24, p = 0.08) and TG levels (r = -0.46, p = 0.0001). After controlling for HRT status, % body fat was correlated with total cholesterol (r = 0.43, p = 0.001), LDL-C (r = 0.38, p = 0.003), HDL-C (r = -0.29, p = 0.025), HDL 2 -C (r = -0,26, p = 0.07) and TG levels (r = 0.40, p = 0.002). Dietary fat intake was similar among the groups. APO E genotype was only associated with plasma lipid profiles in athletes, as those with at least one APO E2 allele tended to have better lipid profiles than those with only APO E3 or E4 alleles. Thus, HRT, exercise training and body composition are associated with plasma lipid levels in postmenopausal women; common polymorphic variations at key lipid metabolism-related gene loci also may interact with exercise training to affect their plasma lipid profiles.

Obesity gene variant and elite endurance performance

beta2-adrenergic receptor (ADRB2) Gln27Glu genotype was determined in sedentary (n = 19), active (n = 20), and elite endurance athletic (n = 24) Caucasian postmenopausal women. Age was similar in all physical activity and ADRB2 genotype groups. ADRB2 genotypes were in Hardy-Weinberg equilibrium in sedentary and active women, but not in the athletes (chi(2) = 4.28, P <.05), due to the near absence of ADRB2 Glu27Glu homozygotes among the athletes. Weight tended to be higher in ADRB2 Glu27Glu women (63.5 +/- 1.8 v 57.7 +/- 1.7 and 60.0 +/- 1.8, P =.08), as did body mass index (BMI) (25.0 +/- 0.4 v 22.9 +/- 0.6 and 23.4 +/- 0.5 kg/m(2), P =.05), due to a higher fat mass in Glu27Glu women (24.1 +/- 1.0 v 18.1 +/- 1.4 and 20.1 +/- 1.4 kg, P <.05). Maximal O2 consumption was lower in ADRB2 Glu27Glu than in ADRB2 Glu27Gln and Gln27Gln genotype women (25.4 +/- 1.1 v 32.4 +/- 1.5 and 29.1 +/- 1.7 mL/kg/min, P <.05). We conclude that the Glu27Glu ADRB2 genotype may dissociate from and the Gln27Gln and Gln27Glu genotypes may associate with elite endurance performance in older women.

Moderate physical activity is associated with higher bone mineral density in postmenopausal women

OBJECTIVES

To determine the associations between different levels of habitual physical activity, hormone replacement therapy (HRT), and bone mineral density (BMD) in postmenopausal women.

DESIGN

Cross-sectional.

SETTING

Academic medical center.

PARTICIPANTS

Twenty sedentary women, 20 active nonathletic women, and 23 endurance-trained athletes, all of whom were postmenopausal, with half of each group on and half not on HRT.

MEASUREMENTS

BMD and body composition determined by dual energy x-ray absorptiometry, maximal oxygen consumption (VO2max), dietary history by questionnaire, and vitamin D receptor (VDR) genotyping on deoxyribonucleic acid.

RESULTS

Body weight was higher in the active nonathletic than in the sedentary and athletic women. Body fat was lower and VO2max higher in the athletic women than in the sedentary and the active nonathletic women. Physical activity level was significantly associated with BMD in three of the five measurements taken (L1-L4 lumbar spine, trochanter, total body; all P < .05). These differences were also generally significant after adjusting for body weight. The association between physical activity status and BMD at the neck of the femur and Ward's triangle bordered on significance (P = .07-.09). At most sites, the active nonathletic women had higher BMD than did the sedentary and athletic women. HRT was significantly associated only with total body BMD (P < .05). The groups were similar in terms of dietary habits (protein, calcium, sodium, phosphorus intake); VDR genotypes; and family, smoking, and nutritional histories.

CONCLUSION

Given the similarity of the groups with respect to other factors that affect BMD, it appears that prolonged low-to-moderate-intensity physical activity, but not the same number of years of higher-intensity training for competitive events, was independently associated with higher BMD.

FABP2 genotype is associated with insulin sensitivity in older women

This study determined whether sequence variations in genes related to glucose and insulin metabolism are associated with insulin sensitivity in postmenopausal women after accounting for habitual physical activity levels, body composition, and hormone-replacement therapy (HRT). Eighteen sedentary, 19 physically active, and 23 athletic postmenopausal white women underwent a frequently sampled intravenous glucose tolerance test to determine insulin sensitivity (S(I)) and dual-energy x-ray absorptiometry to determine body composition. After accounting for the effects of body composition, habitual physical activity levels, and HRT status, S(I) was 26% lower in subjects with the Thr54 fatty acid-binding protein 2 (FABP2) allele compared with Ala54 homozygotes (4.3 +/- 0.5 v 5.8 +/- 0.6 microU x 10(-4)/min/mL; P <.05). Angiotensin-converting enzyme genotype was not significantly associated with S(I). There were no significant associations between Gln27Glu beta(2)-adrenergic receptor or Pro12Ala peroxisome proliferator-activated receptor gamma variants and glucose or insulin kinetic parameters. It was concluded that FABP2 genotype influences insulin sensitivity independent of body composition, habitual physical activity levels, and HRT status in postmenopausal white women.

Is there a disassociation of maximal oxygen consumption and maximal cardiac output?

PURPOSE

The purpose of the present study was to determine whether maximal cardiac output (Q) is affected by the duration of the maximal exercise test.

METHODS

Nine healthy men (N = 6) and women (N = 3) performed three separate maximal treadmill exercise tests, separated by at least 24 h, and underwent a body composition assessment by hydrostatic weighing, all within a 2-wk period. A baseline maximal exercise test was performed to establish VO(2max). The second and third tests, assigned randomly, were designed to elicit the subjects' predetermined VO(2max) in either 6 or 12 min. Heart rate (HR), blood pressure (BP), minutes of ventilation, and oxygen consumption (VO(2)) were measured during all tests. At the end of the 6- and 12-min tests, Q was measured using an acetylene rebreathing technique. Stroke volume (SV), mean arterial pressure (MAP), total peripheral resistance (TPR), and arteriovenous O(2) difference were calculated using standard equations.

RESULTS

Repeated-measures ANOVA indicated that there were no significant differences in HR and VO(2max) between the baseline, 6-min, and 12-min tests. Paired t-tests revealed significantly greater Q (25.1 +/- 5.6 vs 23.7 +/- 5.2 L.min-1) and SV (138.3 +/- 31.5 vs 130.5 +/- 31.2 mL) in the 6- versus 12-min tests, respectively. There were no significant differences in systolic BP, diastolic BP, MAP, TPR, or arteriovenous O(2) difference.

CONCLUSIONS

Despite there being no difference in VO(2max) between the two tests, the 6-min maximal exercise test resulted in a significantly greater Q than the 12-min test, because of a significantly greater SV. Thus, there was a disassociation between VO(2) and Q during maximal exercise.

Insulin sensitivity in postmenopausal women: independent and combined associations with hormone replacement, cardiovascular fitness, and body composition

OBJECTIVE

The effects of combined physical activity and hormone replacement therapy (HRT) on insulin sensitivity in postmenopausal (PM) women are unclear. The purpose of the study was to test the following hypotheses: 1) PM women who have undergone vigorous exercise training have greater insulin sensitivity than PM women who are physically active and PM women who are sedentary, and 2) PM women using HRT have greater insulin sensitivity than PM women not using HRT. We also sought to determine whether body composition or cardiovascular fitness was the stronger predictor of insulin sensitivity in these women.

RESEARCH DESIGN AND METHODS

Three groups of PM women classified as sedentary (n = 18), physically active (n = 19), and athletic (n = 23) underwent an insulin-modified frequently sampled intravenous glucose tolerance test to determine the insulin sensitivity index (SI) and dual-energy X-ray absorptiometry to determine body composition.

RESULTS

There was a significant association between both physical activity (P = 0.036) and HRT (P = 0.007) and fasting plasma insulin levels. The athletic PM women had the lowest plasma insulin levels and the highest SI. Across all physical activity levels, PM women using HRT (n = 29) had significantly lower fasting plasma insulin levels and a lower SI than PM women not using HRT (n = 31). HRT was significantly (P = 0.025) associated with intravenous glucose tolerance (KG); the women not using HRT had a higher K(G); than the PM women using HRT (0.83 +/- 0.08 vs. 0.60 +/- 0.05% per minute). Percent body fat (r = -0.37, P = 0.004) and VO2max (r = 0.35, P = 0.007) were similar predictors of SI.

CONCLUSIONS

We conclude that, although overall HRT was associated with an attenuated SI, vigorous exercise training was independently associated with the greatest SI. In addition, PM women using HRT may benefit from having lower plasma insulin levels, but they may also have a lower SI.

Determinants of body composition in postmenopausal women

BACKGROUND

Little is known about the effects of different levels of long-term physical activity on total body and regional fat and whether hormone replacement therapy interacts with physical activity level to affect body composition in postmenopausal women.

METHODS

We determined the associations between different levels of habitual physical activity, hormone replacement therapy (HRT), and total and regional body composition in postmenopausal women. Twenty sedentary, 20 active nonathletic, and 23 endurance-trained women (approximately half on HRT) had total and regional body composition assessed by dual-energy x-ray absorptiometry. The athletes and active nonathletic women had been active for the same number of years and the same number of hours per week.

RESULTS

The athletes and sedentary women weighed the same, but the active nonathletic groups on and not on HRT weighed 3-12 kg more (p < .05). Athletes had less trunk, arm, leg, and total body fat than sedentary and active nonathletic women (p < .05). Women on HRT tended to have lower total body (p = .07), but not regional, fat values. Linear regression analyses indicated that VO2max in ml/kg/min was the major independent determinant of total and regional body fat accounting for 52% to 70% of their variances. Athletes had greater caloric and carbohydrate intake than their less active peers, but all groups had similar protein, fat, saturated fat, monounsaturated fat, and polyunsaturated fat intakes.

CONCLUSIONS

Intense training, but not low- to moderate-intensity physical activity, is associated with markedly lower levels of total and regional body fat in postmenopausal women. HRT has less of an effect on body composition than intense exercise training in postmenopausal women.

Enhanced cardiovascular hemodynamics in endurance-trained postmenopausal women athletes

PURPOSE

We sought to determine whether older women athletes who had habitually performed vigorous endurance exercise training had higher stroke volumes and cardiac outputs than sedentary postmenopausal women during maximal exercise.

METHODS

Seventeen endurance-trained, postmenopausal women athletes (age 65 +/- 4 yr; VO2max 2.11 +/- 0.31 L x min(-1), 38.3 mL x kg(-1) x min(-1)) and 14 sedentary, postmenopausal women (age 63 +/- 5 yr; VO2max 1.41 +/- 0.22 L x min(-1), 23.7 +/- 3.5 mL x kg(-1) x min(-1)) performed maximal treadmill exercise while cardiac output (via acetylene rebreathing) and other cardiovascular hemodynamics were measured. Approximately half of the subjects in each group were on hormone replacement therapy (HRT).

RESULTS

The greater VO2max of the athletes was the result of a greater cardiac output (12.8 +/- 1.6 vs. 9.3 +/- 1.4 L x min(-1)) resulting from their significantly larger stroke volume (80 +/- 10 vs 57 +/- 10 mL) at maximal exercise. There were no significant differences in maximal cardiac output or maximal stroke volume related to HRT status in the sedentary women or athletes.

CONCLUSIONS

These data indicate that endurance-trained, competitive, postmenopausal women have higher stroke volumes and cardiac outputs during maximal exercise, than their sedentary peers. However, these data suggest that HRT may not affect maximal CV function in sedentary or endurance-trained postmenopausal women.

Ambulatory blood pressure after acute exercise in older men with essential hypertension

We sought to determine whether reductions in blood pressure in hypertensives after acute exercise persist for more than the 2 to 3 h found in controlled laboratory settings. Subjects (n = 11) were obese (32 +/- 4% body fat), sedentary (VO2max 27 +/- 4 mL/kg/min) 60 +/- 6-year-old men with stage 1 or 2 essential hypertension. Ambulatory blood pressure was recorded on 1 day preceded by 45 min of 70% VO2max treadmill exercise and on another day not preceded by exercise. Systolic blood pressure was lower by 6 to 13 mm Hg for the first 16 h after exercise (P < .05) compared to the day without prior exercise. Twenty-four-hour, day, and night average systolic blood pressures were significantly lower on the day after exercise. There was a trend for peak systolic blood pressure to be lower during the entire 24 h and the day portion of the recording; peak systolic blood pressure was significantly lower during the night portion of the recording after exercise. Systolic blood pressure load (percent of systolic blood pressure readings >140 mm Hg) was reduced during the entire 24 h and the day portion of the recording after exercise. Diastolic blood pressure was lower for 12 of the first 16 h after acute exercise (hours 0 to 4, 5 to 8, 13 to 16) (P < .05) compared to the day without prior exercise. Twenty-four-hour, day, and night average diastolic blood pressure was also significantly lower on the recording after exercise. Peak diastolic blood pressure was lower over the entire 24-h period. Diastolic blood pressure load (percent of diastolic blood pressure readings >90 mm Hg) was lower during the entire 24 h and the day portion of the day after exercise. Preliminary data also suggest that common genetic polymorphisms at the angiotensinogen, lipoprotein lipase, and angiotensin converting enzyme loci may affect the blood pressure-lowering response after acute exercise. Thus, in sedentary, obese hypertensive men a single aerobic exercise session reduced blood pressure enough to result in significantly lower 24-h average systolic, diastolic, and mean arterial blood pressure. This could result in a reduced cardiovascular load during the 24 h after acute exercise in older hypertensive men.

Cardiovascular hemodynamics with increasing exercise intensities in postmenopausal women

We sought to determine the cardiovascular responses to increasing exercise intensities in postmenopausal women with different physical activity levels and hormone replacement therapy (HRT) status. Forty-four women (11 sedentary, 19 physically active, 14 master athletes; 24 not on HRT, 20 on HRT) completed treadmill exercise at 40, 60, 80, and 100% of maximal oxygen consumption. Oxygen consumption, heart rate, blood pressure, and cardiac output, determined via acetylene rebreathing, were measured at each exercise intensity. HRT did not affect cardiovascular hemodynamics. Stroke volume (SV) decreased significantly between 40 and 100% of maximal oxygen consumption in all groups, and the decrease did not differ among groups. The greater oxygen consumption of the athletes at each intensity was due to their significantly greater cardiac output, which was the result of a significantly greater SV, compared with both of the less active groups. The athletes had significantly lower total peripheral resistance at each exercise intensity than did the two less active groups. There were no consistent significant hemodynamic differences between the physically active and sedentary women. These results indicate that SV decreases in postmenopausal women as exercise intensity increases to maximum, regardless of their habitual physical activity levels or HRT status.

VO2 max is associated with ACE genotype in postmenopausal women

Relationships have frequently been found between angiotensin-converting enzyme (ACE) genotype and various pathological and physiological cardiovascular outcomes and functions. Thus we sought to determine whether ACE genotype affected maximal O2 consumption (VO2 max) and maximal exercise hemodynamics in postmenopausal women with different habitual physical activity levels. Age, body composition, and habitual physical activity levels did not differ among ACE genotype groups. However, ACE insertion/insertion (II) genotype carriers had a 6.3 ml . kg-1 . min-1 higher VO2 max (P < 0.05) than the ACE deletion/deletion (DD) genotype group after accounting for the effect of physical activity levels. The ACE II genotype group also had a 3.3 ml . kg-1 . min-1 higher VO2 max (P < 0.05) than the ACE insertion/deletion (ID) genotype group. The ACE ID group tended to have a higher VO2 max than the DD genotype group, but the difference was not significant. ACE genotype accounted for 12% of the variation in VO2 max among women after accounting for the effect of habitual physical activity levels. The entire difference in VO2 max among ACE genotype groups was the result of differences in maximal arteriovenous O2 difference (a-vDO2). ACE genotype accounted for 17% of the variation in maximal a-vDO2 in these women. Maximal cardiac output index did not differ whatsoever among ACE genotype groups. Thus it appears that ACE genotype accounts for a significant portion of the interindividual differences in VO2 max among these women. However, this difference is the result of genotype-dependent differences in maximal a-vDO2 and not of maximal stroke volume and maximal cardiac output.

Improvement of insulin sensitivity by short-term exercise training in hypertensive African American women

African American women have a high prevalence of insulin resistance, non-insulin-dependent diabetes mellitus, obesity, and hypertension that may be linked to low levels of physical activity. We sought to determine whether 7 days of aerobic exercise improved glucose and insulin metabolism in 12 obese (body fat >35%), hypertensive (systolic blood pressure > or =140 and/or diastolic blood pressure > or =90 mmHg) African American women (mean age 51+/-8 years). Insulin-assisted frequently-sampled intravenous glucose tolerance tests were performed at baseline and 14 to 18 hours after the 7th exercise session. There was no significant change in maximal oxygen consumption, body composition, or body weight after the 7 days of aerobic exercise. The insulin sensitivity index increased (2.68+/-0.45 x 10[-5] to 4.23+/-0.10 x 10[-5] [min(-1)/pmol/L], P=.02). Fasting (73+/-9 to 50+/-9 pmol/L, P=.02) and glucose-stimulated (332+/-58 to 261+/-45 pmol/L, P=.05) plasma insulin levels decreased. Additional measures related to the insulin resistance syndrome also changed with the 7 days of exercise: basal plasma norepinephrine concentrations were reduced (2.46+/-0.27 to 1.81+/-0.27 nmol/L, P=.02) and sodium excretion rate increased from 100+/-13 to 137+/-7 mmol/d (P=.03); however, there was no change in potassium excretion or 24-hour ambulatory blood pressure. We conclude that a short-term aerobic exercise program improves insulin sensitivity in African American hypertensive women independent of changes in fitness levels, body composition, or body weight. The present study indicates that short-term exercise can improve insulin resistance in hypertensive, obese, sedentary African American women and confirms previous reports that a portion of the exercise-induced improvements in glucose and insulin metabolism may be the result of recent exercise.

Utilization of glycogen but not plasma glucose is reduced in individuals with NIDDM during mild-intensity exercise

To test the hypothesis that substrate utilization during mild-intensity exercise differs in non-insulin-dependent diabetes mellitus (NIDDM) compared with nondiabetic subjects, seven lean healthy subjects (L), seven obese healthy subjects (O), and seven individuals with NIDDM were studied during 40 min of mild-intensity cycling (40% of peak O2 uptake). Systemic utilization of plasma glucose (Glc Rd) was determined by using isotope dilution methods. Gas exchange was measured to determine rates of carbohydrate (CHO) and lipid oxidation. During exercise, when CHO oxidation was greater than Glc Rd, the net oxidation of glycogen was calculated as the difference: CHO oxidation - Glc Rd. During mild-intensity cycling, the respiratory exchange ratio was similar across groups (0.87 +/- 0.02, 0.85 +/- 0.02, and 0.86 +/- 0.01 in L, O, and NIDDM subjects, respectively), and CHO oxidation accounted for one-half of total energy expenditure during exercise. Glc Rd increased during exercise and was greatest in subjects with NIDDM (3.0 +/- 0.2, 2.9 +/- 0.2, and 4.5 +/- 0.4 ml.kg-1.min-1 in L, O, and NIDDM subjects, respectively, P < 0.05), yet Glc Rd was less than CHO oxidation during exercise, indicating net oxidation of glycogen. Glycogen oxidation was greater in L and O than in NIDDM subjects (3.4 +/- 1.0, 2.5 +/- 0.9, and 1.7 +/- 0.8 ml.kg-1.min-1; P < 0.05). In summary, during mild-intensity exercise, NIDDM subjects have an increased Glc Rd and a decreased oxidation of muscle glycogen.

Endurance exercise training improves body composition and plasma insulin responses in 70- to 79-year-old men and women

Forty-two men and women aged 70 to 79 years were studied to assess the effects of 6 months of endurance or resistance training and subsequent cessation of training on glucose tolerance, plasma insulin responses, serum triglyceride and cholesterol levels, and plasma dehydroepiandrosterone (DHEA) levels. The endurance training group (n = 16) exercised at 75% to 85% heart rate reserve for 35 to 45 minutes three times per week; the resistance training group (n = 17) completed one set of eight to 12 repetitions on 10 Nautilus machines three times per week. No significant changes in any variables occurred in a control group (n = 9). Maximal oxygen consumption (VO2max) increased by 20% with endurance training, but did not change with resistance training. Upper- and lower-body strength increased in the resistance training group, but did not change with endurance training. Neither group changed their body weight with training, but the endurance training group elicited a significant reduction in their sum of seven skinfolds and percent body fat. Neither group altered their glucose tolerance with training; however, the endurance training group had lower plasma insulin responses after training compared with the other two groups. Serum lipid and plasma DHEA levels did not change in either the endurance or resistance training groups. Ten days of no exercise following training did not significantly alter body weight or composition, glucose tolerance, plasma insulin responses, or plasma DHEA levels in either the endurance training (n = 10) or resistance training (n = 14) group.(ABSTRACT TRUNCATED AT 250 WORDS)

Energy expenditure during bicycling

This study was designed to measure the O2 uptake (VO2) of cyclists while they rode outdoors at speeds from 32 to 40 km/h. Regression analyses of data from 92 trials using the same wheels, tires, and tire pressure with the cyclists riding in their preferred gear and in an aerodynamic position indicated the best equation (r = 0.84) to estimate VO2 in liters per minute VO2 = -4.50 + 0.17 rider speed + 0.052 wind speed + 0.022 rider weight where rider and wind speed are expressed in kilometers per hour and rider weight in kilograms. Following another rider closely, i.e., drafting, at 32 km/h reduced VO2 by 18 +/- 11%; the benefit of drafting a single rider at 37 and 40 km/h was greater (27 +/- 8%) than that at 32 km/h. Drafting one, two, or four riders in a line at 40 km/h resulted in the same reduction in VO2 (27 +/- 7%). Riding at 40 km/h at the back of a group of eight riders reduced VO2 by significantly more (39 +/- 6%) than drafting one, two, or four riders in a line; drafting a vehicle at 40 km/h resulted in the greatest decrease in VO2 (62 +/- 6%). VO2 was also 7 +/- 4% lower when the cyclists were riding an aerodynamic bicycle. An aerodynamic set of wheels with a reduced number of spokes and one set of disk wheels were the only wheels to reduce VO2 significantly while the cyclists were riding a conventional racing bicycle at 40 km/h.(ABSTRACT TRUNCATED AT 250 WORDS)