Biomedical subjects

T G Babb

Publications and source records attributed to T G Babb.

21 records · Page 2Linked to original sources

PubMed1991

Lung volumes during low-intensity steady-state cycling.

The use of inspiratory capacity (IC) to estimate end-expiratory lung volume (EELV) during exercise has been questioned because of the assumption of constant total lung capacity (TLC). To investigate lung volumes during low-intensity steady-state cycling, we measured EELV by the open-circuit N2 washout method (MR-1, currently Sensormedics 2100) in eight healthy men while at rest and during unloaded and 60-W cycling. TLC was calculated by adding EELV and IC. Measurement variation of TLC was 142 ml at rest, 121 ml during unloaded cycling, and 158 ml during 60-W cycling. TLC did not differ significantly among the three conditions studied. EELV decreased during unloaded (P less than 0.002) and 60-W cycling (P less than 0.001) compared with rest. End-inspiratory lung volume increased only during 60-W cycling (P = 0.03). The decrease in EELV accounted for 100% of the increase in tidal volume during unloaded cycling. Although minute ventilation was similar in the subjects during unloaded cycling, we noted that breathing patterns varied among the subjects. The increase in respiratory frequency was negatively correlated to the change in tidal volume (R2 = 0.54, P = 0.038) and to the change in end-inspiratory lung volume (R2 = 0.68, P = 0.012). We conclude that TLC does not differ significantly during low-intensity steady-state cycling and that use of IC to estimate changes in EELV is appropriate.

Adult↗

PubMed1991

Ventilatory response of moderately obese women to submaximal exercise.

To investigate the effect of moderate obesity on ventilatory responses to graded exercise, we compared the ventilatory responses of ten moderately obese (35 +/- 5 percent body fat) and nine leaner women (22 +/- 2 percent body fat) during walking on a treadmill with incremental increases in percent grade. Speed remained constant at 3.0 mph. In the obese women, VO2 in l/min and ml/FFW/min, fb (b/min), VE (l/min), and HR were significantly greater (P less than 0.05) at all four absolute workloads. At 10.0 and 12.5 percent grade, VO2 (ml/kg/min) was smaller and VE/VO2 was greater in the obese women. The difference in VE/VO2 suggests a lower ventilatory threshold for the obese women. Percent VO2 max and R (VCO2/VO2) were significantly different at 12.5 percent grade only. When VO2 was divided by HR (oxygen pulse), the two groups were not significantly different at any of the four workloads tested. The groups were compared further at workloads representing approximately 55, 65, 75, and 85 percent of VO2 max. HR was not significantly different at any of the four relative exercise intensities. VE was significantly greater in the obese at 85 percent of maximum only (P less than 0.05) and fb was significantly greater at 55, 75, and 85 percent of maximum. Whereas cardiorespiratory responses of moderately obese women are increased at absolute workloads when compared to that of leaner women, HR is similar at comparable intensities of exercise. VE is also similar at comparable intensities of exercise below ventilatory threshold but fb is greater. The effect of the higher fb on exercise tolerance is unknown.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1989

Exercise end-expiratory lung volumes in lean and moderately obese women.

End-expiratory lung volumes (EELV) and expiratory flow rates were determined in 10 moderately obese (mean, 35 percent fat) and 10 relatively lean women (22 percent fat) at rest and during exercise on a treadmill at 55 and 85 percent of VO2max. Expiratory reserve volume (ERV) as a percentage of forced vital capacity (FVC) was used as an index of EELV. Differences in body weight, body fatness, and VO2max were significant (P less than 0.05). The resting EELV in the obese women was less than (P less than 0.01) that in the leaner women (32 vs 37 percent). During exercise at the two intensities, the EELV remained near the resting value in the obese women (approximately 30 percent). In contrast, the leaner women experienced an initial decrease in EELV during exercise at 55 percent of VO2max (i.e., from 37 to 32 percent) (P less than 0.01); thereafter, the EELV changed no further during exercise at 85 percent of VO2max. There were no significant differences in relative expiratory flow rates at rest or during exercise between the obese and lean women. In conclusion, moderately obese women fail to decrease their EELV during exercise in contrast to leaner women who do. A non-linear respiratory system pressure-volume curve, plus increased resistance as maximal flow is approached may combine to determine a lower limit of EELV during exercise.

Body Composition↗