Effects of gender, age, and fitness level on response of VO2max to training in 60-71 yr olds.

The adaptive response of maximal aerobic power (VO2max) to endurance exercise training was compared in 53 men and 57 women, aged 60-71 yr. The subjects were healthy and had been sedentary for at least 2 yr. Pretraining VO2max was measured during graded treadmill walking on two occasions.

Plasma glucose kinetics in a well-trained cyclist fed glucose throughout exercise.

We hypothesized that when plasma glucose availability is maintained by carbohydrate (CHO) ingestion, trained cyclists can utilize plasma glucose at very high rates during the later stages of prolonged exercise (10). To test this hypothesis, a well-trained male cyclist was studied during exercise to fatigue at 70% VO2max when ingesting glucose throughout exercise. A primed continuous infusion of [U-13C]glucose was begun after 60 min of exercise to measure rates of plasma glucose appearance (Ra), disappearance (Rd), and oxidation (R(ox)).

Effects of aging, gender, and physical training on peripheral vascular function.

Background: Blood pressure and total peripheral resistance increase with age. However, the effect of age on vasodilatory capacity has not been characterized.

Methods And Results: To delineate the effects of aging, gender, and physical training on peripheral vascular function, we measured blood pressure during submaximal and maximal treadmill exercise and measured blood pressure, calf blood flow, and calf conductance (blood flow/mean blood pressure) at rest and during maximal hyperemia in 58 healthy sedentary subjects (men aged 25 +/- 5 and 65 +/- 3 years and women aged 27 +/- 5 and 65 +/- 4 years) and in 52 endurance exercise-trained subjects (men aged 30 +/- 3 and 65 +/- 4 years and women aged 27 +/- 3 and 65 +/- 3 years).

Effects of treadmill exercise to exhaustion on the insulin response to hyperglycemia in untrained men.

The effects of a single bout of exercise to exhaustion on pancreatic insulin secretion were determined in seven untrained men by use of a 3-h hyperglycemic clamp with plasma glucose maintained at 180 mg/100 ml. Clamps were performed either 12 h after an intermittent treadmill run at approximately 77% maximum O2 consumption or without prior exercise. Arterialized blood samples for glucose, insulin, and C-peptide determination were obtained from a heated hand vein.

Exercise training enhances leg vasodilatory capacity of 65-yr-old men and women.

To determine whether extremity vasodilatory capacity may be augmented in older persons by endurance exercise training, lower leg blood flow and conductance were characterized plethysmographically at rest and during maximal hyperemia in 9 men and 10 women aged 64 +/- 3 (SD) yr before and after 31 +/- 6 wk of walking and jogging at 70-90% of maximal oxygen uptake for 45 min 3-5 days/wk. Maximal oxygen uptake expressed as milliliters per kilogram per minute improved 25% in men and 21% in women (P less than 0.01).

Effect of exercise on glucose disposal: response to a maximal insulin stimulus.

We used the euglycemic clamp to assess the effects of exercise on maximally insulin-stimulated glucose disposal. In 11 young men, a 60-min bout of exercise had no significant effect on the rate of glucose disposal during a euglycemic clamp performed approximately 30 min postexercise in which plasma insulin was raised to approximately 2,500 microU/ml (a maximal insulin stimulus). The maximal rate of glucose disposal attained during the clamp averaged 15.

The effect of training specificity on maximal and submaximal physiological responses to treadmill and cycle ergometry.

The purpose of this study was to investigate the effect of training specificity during maximal and submaximal treadmill (TM) and bicycle ergometer (BE) exercise. A group of trained runners (RG, no. 7) and trained bikers (BG, no.

Insulin secretory capacity in endurance-trained and untrained young men.

Insulin secretion in response to glucose stimulation is reduced in endurance-trained humans. In this study, a modified hyperglycemic clamp, with a superimposed arginine infusion and fat meal, was performed on eight endurance-trained and nine untrained men to determine whether insulin secretory capacity is reduced by exercise training. Raising the plasma glucose concentration to approximately 450 mg/dl resulted in a plasma insulin response in the trained men that was approximately 64% lower than that of the untrained (peak values: 54 +/- 8 vs.

Exercise and recovery ventilatory and VO2 responses of patients with McArdle's disease.

This study was designed to determine whether patients with McArdle's disease, who do not increase their blood lactate levels during and after maximal exercise, have a slow "lactacid" component to their recovery O2 consumption (VO2) response after high-intensity exercise. VO2 was measured breath by breath during 6 min of rest before exercise, a progressive maximal cycle ergometer test, and 15 min of recovery in five McArdle's patients, six age-matched control subjects, and six maximal O2 consumption- (VO2 max) matched control subjects. The McArdle's patients' ventilatory threshold occurred at the same relative exercise intensity [71 +/- 7% (SD) VO2max] as in the control groups (60 +/- 13 and 70 +/- 10% VO2max) despite no increase and a 20% decrease in the McArdle's patients' arterialized blood lactate and H+ levels, respectively.

Endurance training decreases plasma glucose turnover and oxidation during moderate-intensity exercise in men.

To assess the effects of endurance training on plasma glucose kinetics during moderate-intensity exercise in men, seven men were studied before and after 12 wk of strenuous exercise training (3 days/wk running, 3 days/wk cycling). After priming of the glucose and bicarbonate pools, [U-13C] glucose was infused continuously during 2 h of cycle ergometer exercise at 60% of pretraining peak O2 uptake (VO2) to determine glucose turnover and oxidation. Training increased cycle ergometer peak VO2 by 23% and decreased the respiratory exchange ratio during the final 30 min of exercise from 0.

The ratio of waist-to-hip circumference, plasma insulin level, and glucose intolerance as independent predictors of the HDL2 cholesterol level in older adults.

High plasma levels of HDL2, a subfraction of high-density lipoprotein (HDL) cholesterol, are associated with a reduced risk of coronary heart disease. To investigate the characteristics related to HDL2 cholesterol levels, we measured lipoprotein levels and several metabolic and anthropometric variables in 146 healthy subjects (77 men and 69 women) in the seventh decade of life. The level of HDL2 cholesterol was inversely correlated with the ratio of the waist-to-hip circumference (r = -0.

Longitudinal assessment of responses by triathletes to swimming, cycling, and running.

Fourteen triathletes (eight male, six female) were tested four times (in February, May, August, and October) to monitor adaptations to training for a triathlon (1.9-km swim, 90.3-km bike, 21.

Measurement of fat distribution by magnetic resonance imaging.

Because of the important role of intra-abdominal fat in predicting increased risk for diabetes, hypertension, and heart disease, methods to quantify intra-abdominal fat are needed. Computed tomography defines quantity of intra-abdominal fat but is associated with significant radiation risk. We explored using magnetic resonance imaging (MRI) to measure amount and distribution of intra-abdominal fat.

Ten kilometer performance and predicted velocity at VO2max among well-trained male runners.

Previous research (study 1) has shown that a significant relationship exists between 10 km run time (RT) and predicted running velocity at VO2max (vVO2max) among well-trained males heterogeneous in VO2max. Since competitive runners often display a homogeneous fitness profile, the purpose of this study was to determine the association between 10 km RT and vVO2max among a group of trained runners exhibiting nearly identical VO2max values (study 2). Running economy (RE), vVO2max, and velocity at a 4 mM blood lactate concentration (v at 4 mM BL) were calculated in both studies.

Effects of respiratory muscle endurance training on ventilatory and endurance performance of moderately trained cyclists.

This study examined the effects of respiratory muscle endurance training (RMET) on ventilatory and endurance performance among moderately trained, male cyclists. Nine subjects initially completed two cycling VO2 max tests, two endurance cycling tests for time at 95% VO2 max, a 15-s MVV test, and an endurance breathing test for time at 100% MVV. Four subjects then underwent 3 weeks of strenuous RMET while five served as controls.

Fluid shifts with successive running and bicycling performance.

Seven men and five women triathletes ran 10 km and bicycled 40 km at race pace for the purpose of studying changes in plasma, blood, and red blood cell volumes. A second trial followed 1 wk later with the order of exercise counterbalanced (running first-cycling second; cycling first-running second). Water consumption was measured by providing water bottles on the bike phase, at 3.

Physiological responses of triathletes to maximal swimming, cycling, and running.

The objectives of this study were to: (a) develop a physiological profile for a group of trained triathletes and (b) determine whether multiple modes of training result in general or specific adaptations. VO2max of 13 trained triathletes (mean = 29.5 yr) was measured during treadmill running (TR), cycle ergometry (CE), and tethered swimming (TS) over a 6-wk period encompassing a half-triathlon (1.

Effects of shoes and foot orthotics on VO2 and selected frontal plane knee kinematics.

The objective of this study was to investigate the effects of shoes and foot orthotics on running economy and selected frontal plane knee kinematics during the support phase of running. Twenty-one male runners who had been fitted with orthotics served as subjects. Subjects participated in three submaximal runs on a treadmill under the following conditions: barefoot, shoes, and shoes plus orthotics.