Laboratory and field assessments were made on eighteen male distance runners. Performance data were obtained for distances of 3.2, 9.7, 15, 19.3 km (n = 18) and the marathon (n = 13). Muscle fiber composition expressed as percent of slow twitch fibers (%ST), maximal oxygen consumption (VO2max), running economy (VO2 for a treadmill velocity of 268 m/min), and the VO2 and treadmill velocity corresponding to the onset of plasma lactate accumulation (OPLA) were determined for each subject. %ST (R-.47), VO2max (r greater-than-or-equal-to .83), running economy (r greater-than-or-equal-to .49), VO2 in ml/kg min corresponding to the OPLA (r greater-than-or-equal-to .91) and the treadmill velocity corresponding to the OPLA (r greater-than-or-equal-to .91) were significantly (p<.05) related to performance at all distances. Multiple regression analysis showed that the treadmill velocity corresponding to the OPLA was most closely related to performance and the addition of other factors did not significantly raise the multiple R values suggesting that these other variables may interact with the purpose of keeping plasma lactates low during distance races. The slowest and fastest marathoners ran their marathons 7 and 3 m/min faster than their treadmill velocities corresponding to their OPLA which indicates that this relationship is independent of the competitive level of the runner. Runners appear to set a race pace which allows the utilization of the largest possible VO2 which just avoids the exponential rise in plasma lactate.

The present study describes a modification of the equilibration CO2-rebreathing technique for determining cardiac output (Q), utilizing the Beckman Metabolic Measurement Cart (MMC) to provide partial automation of the procedures described by Jones et al. (Clinical Exercise Testing. Philadelphia, PA: Saunders, 1975). Q was determined in six normal healthy males to establish the reliability of the technique at rest, and during exercise at power outputs of 49 and 98 W, or 300 and 600 kpm/min. An additional 11 patients, who were symptomatic for coronary artery disease and scheduled for right and left heart catheterization, were used in validating these procedures against Q determined by the thermodilution method. The automated CO2-rebreathing procedure was found to be reliable at rest and during exercise, and demonstrated a direct linear relationship with VO2 (r = 0.90). Also, this procedure correlated (r = 0.87) with the thermodilution method during supine rest, and both methods were quite consistent between trials within the same subject. It was concluded that the CO2-rebreathing procedure used in this study, as interfaced with the Beckman MMC, provides reasonable estimates of Q, both in patients during supine rest, and in normal healthy subjects at rest and during low to moderate levels of exercise.

WILMORE, JACK H., PAUL A. VODAK, RICHARD B. PARR, ROBERT N. GIRANDOLA, and JOHN E. BILLING. Further simplification of a method for determination of residual lung volume. Med. Sci. Sports Exercise. Vol. 12, No. 3, pp. 216–218, 1980. This paper describes a modification of the standard oxygen-dilution technique for determining residual lung volume, whereby rapid responding oxygen and carbon dioxide analyzers are used to determine the point of nitrogen equilibration, and a five-liter rebreathing bag is substituted for the standard spirometer. This simplified method reduced the total test time to five min or less for duplicate determinations, and eliminated the need for a nitrogen analyzer and a spirometer. This method was found to be both reliable (r = 0.99) and valid (r = 0.92), with a standard error of prediction of 125 ml, and a mean difference of only eight ml, when compared with the established oxygen-dilution technique on a sample of 76 healthy men and women, 19 to 55 years of age. In a subsample of 13 subjects, residual volume was also determined with the nitrogen washout technique, which correlated r=0.89 and r=0.91 with the established and modified oxygen-dilution techniques respectively. The use of assumed values for the initial and final alveolar concentrations of nitrogen did not appear to significantly influence the final results.

Laboratory and field assessments were made on eighteen male distance runners. Performance data were obtained for distances of 3.2, 9.7, 15, 19.3 km (n = 18) and the marathon (n = 13). Muscle fiber composition expressed as percent of slow twitch fibers (%ST), maximal oxygen consumption (Vo2max), running economy (Vo2 for a treadmill velocity of 268 m/min), and the Vo2 and treadmill velocity corresponding to the onset of plasma lactate accumulation (OPLA) were determined for each subject. %ST (R greater than or equal to .47), Vo2max (r greater than or equal to .83), running economy (r greater than or equal to .49), Vo2 in ml/kg min corresponding to the OPLA (r greater than or equal to .91) and the treadmill velocity corresponding to the OPLA (r greater than or equal to .91) were significantly (p less than .05) related to performance at all distances. Multiple regression analysis howed that the treadmill velocity corresponding to the OPLA was most closely related to performance and the addition of other factors did not significantly raise the multiple R values suggesting that these other variables may interact with the purpose of keeping plasma lactates low during distance races. The slowest and fastest marathoners ran their marathons 7 and 3 m/min faster than their treadmill velocities corresponding to their OPLA which indicates that this relationship is independent of the competitive level of the runner. Runners appear to set a race pace which allows the utilization of the largest possible Vo2 which just avoids the exponential rise in plasma lactate.

in younger adults (Kohrt et al. 1991). The interrelationships of age, \i02max, and training status are evident when the loss inVO,max with age is compared for active and sedentary individuals (Figure 3-5). When the cardiorespiratory responses of an older adult are coinpared with those of a young or middle-aged adult at the same absolute submaximal rate of work, stroke volume for an older person is generally lower and heart rate is higher from the attempt to maintain cardiac output. Because this attempt is generally insufficient, the A-+0, difference must increase to provide the same submaximal oxygen uptake (Raven and Mitchell 1980; Thompson and Dorsey 1986). Some researchers have shown, however , that cardiac output can be maintained at both submaximal and maximal rates of work through a higher stroke volume in older adults (Rodeheffer et al. 1984). The deterioration in physiological function normally associated with aging is, in fact, caused by a combination of reduced physical activity and the aging process itself. By maintaining an active lifestyle, or by increasing levels of physical activity if previously sedentary, older persons can maintain relatively high levels of cardiovascular and metabolic function, including irO,max (Kohrt et al. 199 1)) and of skeletal muscle function (Rogers and Evans 1993). For example, Fiatarone and colleagues (1994) found an increase of 113 percent in the strength of elderly men and women (mean age of 87.1 years) following a lo-week training program of progressive resistance exercise. Cross-sectional thigh muscle area was increased, as was stair-climbing power, gait velocity, and level of spontaneous activity. Increasing endurance and strength in the elderly contributes to their ability to live independently. Differences by Sex For the most part, women and men who participate in exercise training have similar responses in car-diovascular, respiratory, and metabolic function (providing that size and activity level are normal-iced). Relative increases in\jO,max are equivalent Figure 3-5. Changes in 00, max with aging, comparing an active population and sedentary population (the figure also illustrates the expected increase in VO, max when a previously sedentary person begins an exercise program) A-Active adults R&&on in activity plus weight gain Sedentary adults Physiologic Responses and Long-Term Adaptations to Exercise for women and men (Kohrt et al. 1991; Mitchell et al. 1992). Some evidence suggests that older women accomplish this increase inVO,max mainly through an increase in the AGO, difference, whereas younger women and men have substantial increases in stroke volume, which …