Search PubMed⌕ Search

Biomedical subjects

L D Zwiren

Publications and source records attributed to L D Zwiren.

5 recordsLinked to original sources
PubMed1991

Estimation of VO2max: a comparative analysis of five exercise tests.

Thirty-eight female subjects (M +/ SD = 33 +/- 3.0 years) had VO2max measured on the cycle ergometer (M +/- SD = 37.3 +/- 6.4 ml.kg-1.min-1) and on the treadmill (M +/- SD = 41.3 +/- 6.6 ml.kg-1.min-1). VO2max was estimated for each subject from heart rate (HR) at submaximal workloads on the cycle ergometer using the Astrand-Rhyming nomogram (A/R) and the extrapolation method (XTP). VO2max was also estimated from three field tests: 1.5-mile run (RUN) (independent variable [IV] = time), mile walk (WALK) (IV = time, age, HR, gender, body weight), and the Queens College Step Test (ST) (IV = HR during 5-20 s recovery). Repeated measure ANOVA revealed significant mean differences between the criterion cycle ergometer VO2max versus A/R and XTP (20 and 12% overestimation). The WALK, RUN, and ST VO2max values were not significantly different from the criterion treadmill VO2max. The correlation between criterion VO2max estimated from the WALK and RUN were r = .73 (SEE = 4.57 ml,kg-1.min-1) and r = .79 (SEE = 4.13 ml.kg-1.min-1), respectively. The ST, A/R, and XTP had higher SEEs (13-13.5% of the mean) and lower r s (r = .55 to r = .66). These results suggest both the WALK and RUN tests are satisfactory predictors of VO2max in 30 to 39-year-old females.

Adult↗
PubMed1983

Comparison of circulatory responses to submaximal exercise in equally trained men and women.

In previous studies comparing circulatory responses to exercise in men and women, the habitual physical activity of the groups was not documented. Thus, it is possible that sex differences observed were partly a function of differences in level of physical condition. The purpose of this study was to compare central circulatory responses to submaximal bicycle ergometer exercise in equally trained men and women. Cardiac output (Q), stroke volume (SV), heart rate (HR), and arteriovenous oxygen content difference [(a-v)O2 diff] were determined at approximately 30%, 50%, 70%, and 90% VO2max in 18 male and 18 female trained young adults. Q was determined by the CO2 -rebreathing method. The men and women had similar training backgrounds and nonsignificantly different mean VO2max in ml . kg FFW-1 . min-1 (62.3 and 60.3, respectively). Mean differences between men and women in Q (0.44 l . min-1), HR (23 bts . min-1), and (a-v)O2 diff at 1.5 l . min-1 and in heart rate at various percentages of VO2max (2-4 bts . min-1) were smaller than in previous research. Smaller sex differences in various VO2max expressions in the present study suggest that there was a difference between males and females in habitual physical activity in earlier research. It is concluded that a portion of previously reported sex differences in certain circulatory responses to submaximal exercise was a consequence of different levels of physical condition of the male and female subjects. The magnitude of gender-related differences in circulatory responses to submaximal exercise appears to be smaller than previously thought.

Adult↗
PubMed1975

Maximal oxygen consumption test during arm exercise--reliability and validity.

The reliability and validity of a continuous progressive arm test, in which maximal 02 consumption (V02 max arm) is determined, were analyzed. Forty-one men (28.2 +/- 8.8 yr) performed the test twice. Eighteen additional men (22.6 +/- 5.6 yr) performed the arm test, as well as the treadmill run, in which maximal O2 consumption VO2max leg) was determined. The validity of the VO2 max arm test was computed, using VO2 max leg as a criterion for the individual's aerobic capacity. The reliability coefficients of VO2 max arm, VEmax arm, and HRmax arm were 0.94, 0.98, and 0.76, respectively, indicating a high reliability of the testmthe validity coefficient of VO2max arm was only 0.74. The regression equation of VO2max leg on VO2max arm was y = 24.4 + 0.9 +/- 4.4 (Syx). These findings indicate that, following the suggested protocol, the individual repeatedly uses the same muscles and does reach an all-out stage. However, different individuals apparently are aided by their trunk and leg muscles to different degrees, which lowers the validity of this test as a predictor of aerobic capacity.

Adult↗
PubMed1975

Responses to exercise of paraplegics who differ in conditioning level.

The purpose of this study was to evaluate the cardiopulmonary function and body composition of sedentary and highly active paraplegics. Four age-matched groups of men (n = 41) were studied: wheelchair-bound sedentary (WS), wheelchair-bound athletes of international caliber (WA), able-bodied sedentary (NS), and able-bodied athletes of national Israeli teams (NA). Although of similar height, WS were significantly (p less than .05) heavier and more obese (skinfolds) than WA and NS. Maximal oxygen consumption (VO2max arm), as measured during arm ergometry by direct open circuit spirometry, was significantly lower in WS (19.58 plus or minus 5.53 ml/kg per min) than in WA (35.00 plus or minus 7.55). The latter had significantly higher VO2max arm than did NS (25.79 plus or minus 3.98). However, no significant difference was observed between WA and NA (38.05 plus or minus 6.25). A similar trend, favoring WA over WS, was shown for maximal minute ventilation and maximal oxygen pulse. Functional lung volumes (FVC, FEV1.0, MBC) did not differ significantly between WA and WS. Heart rates at submaximal work loads were higher in WA than in NA, but markedly lower than in WS. Clear-cut conclusions can be obtained only by a longitudinal study, but these data suggest a marked decrement in cardiopulmonary functions, related to the oxygen transport system, in men whose lower limbs have been immobilized for years. A reversed trend is shown for paraplegics who regularly activate their upper limbs and trunk muscles.

Adult↗