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Accuracy of prediction equations to estimate submaximal VO2during cycle ergometry: The HERITAGE Family Study. Med. Sci. Sports Exerc.,Vol. 31, No. 1, pp. 183-188, 1999. It was hypothesized that more accurate equations for estimating submaximal VO2during cycle ergometry could be developed if more independent variables were used in the equation.

Adouble-blind, parallel-group, placebo-controlled study was conducted to determine the acute physiologic responses to maximal exercise consequent to chronic beta-adrenergic blockade. Twenty-eight healthy, male subjects were tested twice on a treadmill to the point of volitional fatigue using the Bruce protocol and were then randomly assigned to either the placebo (N = 14) or the beta-blockade group (N = 14). The beta-blocking agent sotalol was administered once daily (320 mg/day) for a period of seven days, after which subjects were given a third treadmill test to exhaustion. Oxygen uptake and heart rate were assessed each minute until the respiratory exchange ratio reached 0.95, at which point oxygen uptake was assessed at 30-second intervals. Beta blockade significantly reduced maximal heart rate (191 ± 8.8 versus 150 ± 13.2 beats/min, P < .05) but did not alter treadmill time to exhaustion (676 ± 44 versus 671 ± 57 sec). Maximal oxygen uptake was significantly reduced (43.6 ± 5.8 versus 42.0 ± 5.4 ml/kg/min, P < .05), but this small difference was not considered physiologically significant. No differences were identified in the placebo group for maximal heart rate (195 ± 7.2 versus 193 ± 7.2 beats/min), maximal oxygen uptake (43.9 ± 6.0 versus 43.7 ± 5.1 ml/kg/min), or treadmill time to exhaustion (701 ± 85 versus 705 ± 79 sec). Results indicate that beta-adrenergic blockade with the drug sotalol has little or no effect on physical work capacity and suggest that stroke volume and possibly peripheral oxygen extraction are enhanced at maximal exercise during beta blockade.

The Effect of beta-adrenergic blockade on obtaining a trained exercise state was determined in a sample of 27 healthy adult males (mean age 24 years). For control purposes, subjects were given two maximal treadmill exercise tests, then were randomly assigned to either a placebo group or a beta-adrenergic blocking drug group (sotalol, 320 mg/day). A third maximal treadmill test was administered one week after the initiation of medication. Subjects then participated in a 13-week training program in which they exercised 45 minutes per day five days per week at a training heart rate equivalent to 75 of measured maximal oxygen uptake. Subjects underwent a fourth maximal treadmill test at the conclusion of the training program while under medication; seven days after cessation of medication subjects performed a fifth maximal treadmill test. Maximal oxygen uptake was increased following training in both groups; however, in the beta-blocked group this was manifest only when the subjects were no longer blocked, i.e., uptake did not change while the subjects were still taking beta-blocking drugs. This observation points to the importance of both stroke volume and heart rate in defining the adaptability of the oxygen transport system.

The effects of endurance running on body composition, menstrual cycles, and gonadotropins were studied in 19 healthy, young, regularly menstruating women. Midfollicular plasma concentrations of unstimulated and gonadotropin-releasing hormone (GnRH)-stimulated luteinizing hormone and follicle-stimulating hormone were examined at baseline and after each subject’s weekly mileage had increased 30 miles (Δ30) and 50 miles (Δ50) above baseline. Mean±standard error of the mean unstimulated luteinizing hormone and follicle-stimulating hormone did not change significantly. GnRH-stimulated luteinizing hormone was 76.3±22.0μg/min/ml at baseline and declined to 20.2±4.5μg/min/ml at Δ50 (P<0.02). GnRH-stimulated follicle-stimulating hormone was 28.4±7.0μg/min/ml at baseline and declined to 9.6±2.1μg/min/ml at Δ50 (P<0.02). There were no significant correlations between changes in body composition and changes in gonadotropin responses. Eighteen subjects developed oligomenorrhea.

Nineteen women participated in a 15-month endurance training program to determine the effects of running on plasma total cholesterol, high-density lipoprotein cholesterol (HDL-C), and body composition. Women who were initially running a mean of 15.1 miles/week were selected to minimize the number of dropouts. Total cholesterol, HDL-C, and body composition (hydrostatic technique) were measured at baseline and when individual running mileage had increased above baseline by 30 (Δ30) and 50 (Δ50) mileslwk. Total cholesterol and total body weight did not change. High-density lipoprotein cholesterol was 59.6 mg/dl at baseline and increased to 63.7 mgldl and 69.4 mgldl at Δ30 and Δ50, respectively (P< .001). Lean weight increased from 42.5 kg at baseline to 43.8 kg and 44.6 kg at Δ30 and Δ50, respectively (P< .001). The increases in HDL-C correlated with the increases in lean weight (r= .65, P< .002). Subjects with the lowest baseline HDL-C had the greatest increase in HDL-C at Δ30 and Δ50 (r= −.64, P= .03 and r= −.82, P< .001, respectively). Endurance training of women results in a significant increase in HDL-C that is due either to the training itself or to the associated increase in lean weight or both.