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Biomedical subjects

A Weltman

Publications and source records attributed to A Weltman.

At least 73 records · Page 4Linked to original sources
PubMed1991

Perceptual responses and blood lactate concentration: effect of training state.

The present study investigated the effect of training state on ratings of perceived exertion obtained at the lactate threshold (LT) and fixed blood lactate concentrations (FBLC) of 2.0, 2.5, and 4.0 mM. Runners (N = 20) and nonrunners (N = 29) completed a progressive horizontal treadmill (TM) running test which allowed identification of the TM velocities associated with the LT and FBLC. Runners attained significantly higher TM velocities, greater VO2, greater VE, greater heart rate, and a lower ventilatory equivalent for oxygen (VE/VO2) at each exercise intensity, with the exceptions of heart rate at 4.0 mM and VE/VO2 at the LT. Compared to nonrunners, runners also attained higher VO2, VE, and heart rate relative to peak values at LT and 2.0, 2.5, and 4.0 mM. Despite these relative and absolute physiological differences, there were no differences between groups in local, central, or overall ratings of perceived exertion (RPE) (Borg scale) at any condition. The data from both groups were combined to give the following means and SD for overall RPE during horizontal running: at the LT-11.0 +/- 2.0, and at FBLC of 2.0 mM-13.7 +/- 2.1, 2.5 mM-14.5 +/- 1.8, and 4.0 mM-16.5 +/- 2.3.

Adult↗
PubMed1991

Effect of exercise modality on ratings of perceived exertion at various lactate concentrations.

The effect of exercise modality on the relationship between ratings of perceived exertion (RPE), blood lactate concentration, oxygen uptake (VO2), and heart rate (HR) was examined in 29 untrained male subjects who completed counterbalanced VO2max/lactate threshold (LT) protocols on a cycle ergometer (CE) and treadmill (TM). Heart rate, VO2, and RPE were determined at power outputs corresponding to LT and fixed blood lactate concentrations (FBLC) of 2.0, 2.5, and 4.0 mM and during maximal exercise. A repeated measures ANOVA indicated that, despite significant differences across exercise modality in HR and VO2 at LT, FBLC, and maximal exercise, no significant differences in RPE were found between exercise modalities during leg exercise. Mean (+/- SD) respective values for overall RPE at LT and FBLC of 2.0 mM, 2.5 mM, 4.0 mM, and max were 10.2 (2.2), 13.1 (2.1), 14.1 (2.3), 15.9 (2.3), and 18.8 (1.3) for the CE and 10.8 (1.9), 13.8 (1.8), 14.6 (1.6), 16.2 (2.6), and 18.5 (1.5) for the TM. It was concluded that exercise modality does not affect the perception of exertion at LT, FBLC, or maximal exercise and that a strong relationship exists between RPE and blood lactate concentrations.

Adult↗
PubMed1990

Clinical utility of cycle exercise for the physiologic assessment of growth hormone release in children.

The clinical utility of exercise as a stimulus for the physiologic assessment of growth hormone (GH) deficiency was examined in healthy children. In response to exercise tests performed on different days, serum GH concentrations exceeded 7 micrograms/L on both days in 9 of 10 children. Although there is variation in this method of physiologic testing in the response of serum GH concentration (significant mean differences in GH peak values, 27.1 vs 19.8 micrograms/L for the two tests), the exercise test proved clinically valid in that diagnostic levels of GH were exceeded on both days 90% of the time. We conclude that this exercise evaluation protocol has clinical utility for the assessment of GH deficiency in children.

Adolescent↗
PubMed1990

Reliability and validity of a continuous incremental treadmill protocol for the determination of lactate threshold, fixed blood lactate concentrations, and VO2max.

Fifteen male runners were tested on two occasions to determine the reliability of a continuous incremental level running treadmill protocol (C), with 3-min stages, for lactate threshold (LT) and fixed blood lactate concentration (FBLC) (2.0 mM, 2.5 mM, 4.0 mM) assessment. Test-retest (T-RT) reliability coefficients for velocity at LT, 2.0 mM, 2.5 mM, and 4.0 mM were r = 0.89, 0.91, 0.95, and 0.95, respectively (velocity ranged from 215.3 m/min at LT to 273.6 m/min at 4.0 mM). Mean differences in T-RT velocity values ranged from 0.7 m/min (at LT) to 6.0 m/min (at 2.5 mM; 252.3 m/min vs 258.3 m/min; NS) and the standard errors of measurement were less than +/- 10.0 m/min. Similar results were observed for VO2, with T-RT r values ranging from r = 0.82 (at LT) to r = 0.88 (at 2.0 mM) (VO2 ranged from 47.2 ml/kg.min-1 at LT to 60.9 ml/kg.min-1 at 4.0 mM; VO2 peak = 65.6 ml/kg.min-1). Mean differences in T-RT VO2 values were less than 1.4 ml/kg.min-1 (NS) and the standard errors of measurement were less than +/- 2.95 ml/kg.min-1. Interinvestigator and intrainvestigator reliability coefficients were high and ranged from r = 0.91 to r = 0.99. Validity of C was assessed in an additional 16 male runners who completed C and a criterion discontinuous (D) protocol (using a series of 10-min stages) for LT and FBLC assessment. Results indicated that C and D resulted in similar VO2 and velocity values at LT and FBLC.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Percentages of maximal heart rate, heart rate reserve and VO2max for determining endurance training intensity in male runners.

The use of 60%-95% of maximal heart rate (HR), heart rate reserve (HRR) and VO2max as exercise training intensities was examined in male runners, and these intensities were related to VO2 observed at the lactate threshold (LT) and fixed blood lactate concentrations (FBLC) of 2.0, 2.5, and 4.0 mM. Thirty-one subjects (means age = 29.9 +/- 9.1 yrs; means ht = 177.3 +/- 8.2 cm; means wt = 69.2 +/- 9.9 kg) completed a level running treadmill protocol. The mean values at LT, FBLC of 2.0, 2.5, 4.0 mM and max for VO2 were 52.7, 56.4, 58.0, 61.2 and 63.5 ml/kg.min -1, respectively: for velocity they were 237.4, 252.2, 260.6, 274.4 and 286.5 m/min, respectively; and for HR were 165.7, 172.7, 176.5, 182.3 and 187.4 bts/min, respectively. The majority of subjects were not above LT (N = 20), until an intensity of 90% HR max was attained. At 95% HR max the majority of subjects were above 2.0 mM (N = 23) and 2.5 mM (N = 17) but below 4.0 mM (N = 26). For HRR, 85% HRR was necessary for the majority of subjects to be above LT (N = 20), 90% HRR resulted in the majority of subjects being above 2.0 mM (N = 19), while 95% HRR was required for the majority of subjects to be above 2.5 mM (N = 23). At 95% HRR 14 subjects were above 4.0 mM. For % VO2max, the intensities required for the majority of subjects to be above LT, FBLC of 2.0, and 2.5 mM were 90%, 95% and 95% VO2max, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Effects of training specificity on the lactate threshold and VO2 peak.

We examined the effects of training specificity on the lactate threshold (LT) and VO2peak. Sixteen male subjects completed VO2peak/LT protocols on the cycle ergometer (CE) and treadmill (TM) before and after a training program. The subjects were assigned to run training (N = 5), cycle training (N = 6), and control groups (N = 5). Subjects trained 4 day/week for 10 weeks at approximately 89% of pre-training VO2peak. Results indicated that run training increased VO2 at LT (VO2LT) within both the CE and TM protocols (17.9 to 22.5 ml/kg.min-1 for CE, 22.7 to 36.0 ml/kg.min-1 for TM, p less than 0.05) with the 58.5% increase in VO2LT for TM being greater than the 30.3% increase for CE (p less than 0.05). Cycle training resulted in a 38.7% increase in CE VO2LT (19.7 to 27.4 ml/kg.min-1, p less than 0.05) with no significant improvement in TM VO2LT (23.6 to 24.0 ml/kg.min-1). Similar increases in VO2peak were observed for CE and TM protocols for both cycle and run training groups (VO2peak increased by 11.9 to 20.7% in both CE and TM regardless of training mode). No changes were observed in the control group for any variable. The present data suggest that increases in LT resulting from training may be specific to the mode of exercise.

Adult↗
PubMed1990

Prediction of lactate threshold (LT) and fixed blood lactate concentrations (FBLC) from 3200-m running performance in women.

The present study evaluated the accuracy of predicting velocity and oxygen consumption (VO2) at the LT lactate threshold and FBLC fixed blood lactate concentrations from a 3200-m time trial in women. Forty-four women (mean age = 31.1 yrs, mean ht = 164.9 cm, mean wt = 65.0 kg) completed a treadmill protocol for the determination of LT and FBLC and a 3200-m time trial. Velocity and VO2 values at LT, FBLC of 2.0 2.5, and 4.0 mM, and peak were determined. Mean VO2 and velocity ranged from 27.8 +/- 10.8 ml/kg.min-1 at LT to 42.5 ml/kg.min-1 at peak and from 129.8 +/- 44.0 m.min-1 at LT to 187.0 +/- 52.4 m.min-1 at peak, respectively. Results indicated that a 3200-m time trial (mean time = 20.6 +/- 6.6 min) was a good predictor of VO2 and velocity at LT, FBLC, and peak. Correlation coefficients (using a quadratic model) for velocity ranged from R = 0.96 to R = 0.98 with SEE ranging from 9.0 to 13.1 m.min-1. Correlation coefficients for VO2 ranged from R = 0.94 to R = 0.96 with SEE ranging from 2.8 to 3.6 ml/kg.min. The validity of these regression equations was examined in 13 women who completed a 12-month running program (VO2 LT, VO2 at FBLC of 2.0, 2.5 and 4.0 mM, and VO2 peak increased by 34.7, 19.9, 16.9, 11.9, and 5.4%, respectively, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Release of luteinizing hormone and growth hormone after recovery from maximal exercise.

Pulsatile properties of luteinizing hormone (LH) and growth hormone (GH) release were evaluated in 19 eumenorrheic untrained females [mean age 31.1 +/- 1.1 yr, height 165.2 +/- 1.4 cm, weight 64.8 +/- 2.1 kg, peak oxygen uptake (Vo2) 41.6 +/- 1.4 (SE) ml.kg-1.min-1] during the early follicular phase of the menstrual cycle (days 3-4 after the onset of menses). Each subject was studied during two consecutive menstrual cycles under each of two conditions in random order: 1) no formal exercise for 72 h (C) and 2) 12-24 h after two maximal exercise bouts (peak Vo2/lactate threshold treadmill evaluation and a 3,200-m time-trial run or a maximal Vo2 inclined treadmill test) performed on consecutive days (EX). Blood sampling was performed every 10 min for 12 h. LH and GH pulsatile parameters were identified and characterized by the Cluster pulse detection algorithm. No significant differences were noted in the number of peaks, peak amplitude, interpeak interval, peak increment, or 12-h integrated concentrations between C and EX for LH or GH. We conclude that maximal exercise protocols typically used for exercise evaluation do not have an effect on the pulsatile characteristics of LH or GH release in untrained women during the early follicular phase of the menstrual cycle if 12-24 h of recovery are allowed before evaluation of the pulsatile secretion of gonadotropins or GH.

Adult↗
PubMed1990

Reliability of estimates of pulsatile characteristics of luteinizing hormone and growth hormone release in women.

The test-retest reliability of estimates of pulsatile LH and GH release was evaluated in 23 eumenorrheic women during the early follicular phase of the menstrual cycle. Each subject was studied during two successive or near-successive menstrual cycles by repetitive blood sampling every 10 min for 24 h. Pulsatile parameters for LH and GH release were identified and characterized using the Cluster pulse detection algorithm. For LH, no significant differences existed in any parameter mean between the two 24-h admissions. Correlation coefficients for consecutive 24-h studies ranged from r = 0.22 (P less than 0.32) for number of LH peaks to r = 0.79 (P less than 0.0001) for 24-h integrated LH values (area under the concentration vs. time curve). No significant mean differences in any parameter were observed for consecutive 24-h GH evaluations. Correlation coefficients for 24-h GH ranged from r = 0.25 (P less than 0.34) for nadir to r = 0.71 (P less than 0.002) for incremental peak increase. Cosinor analysis was used to determine significant 24-h variations in LH and GH concentrations. Statistically significant differences existed between admissions for the amplitude of the nyctohemeral LH rhythm and its acrophase (time at which maximal hormone value was attained), but no mean differences were found for mesor (mean concentration). Correlation coefficients for LH were r = 0.10 (P less than 0.65), r = 0.43 (P less than 0.08), and r = 0.78 (P less than 0.0001) for phase, amplitude, and mesor, respectively. No significant mean differences existed for any parameter of nyctohemeral GH rhythms. Correlation coefficients were r = -0.18 (P less than 0.52), r = 0.49 (P less than 0.72), and r = 0.14 (P less than 0.80) for 24-h GH amplitude, phase, and mesor, respectively. We conclude that comparisons of mean and integrated LH and GH concentrations over a 24-h interval in the early follicular phase of the menstrual cycle are reliable; however, certain pulsatile properties responsible for the achievement of the mean daily concentrations of LH and GH may be nonuniform from menstrual cycle to menstrual cycle. In addition, nonuniformities may exist in the nyctohemeral rhythms of serum concentrations of LH and GH in the adult woman between cycles when a single 24-h time series is the basis for the analysis.

Adult↗
PubMed1990

Physiological effects of a weight loss regimen practiced by college wrestlers.

The effects of weight loss (dehydration) techniques (which mimicked techniques used prior to actual competition) used by intercollegiate wrestlers on selected physiological parameters (strength, anaerobic power, anaerobic capacity, the lactate threshold (LT), and peak aerobic power) were examined in seven intercollegiate wrestlers. During the 36 h weight loss period, subjects lost 3.3 kg (4.9% body weight), all of which occurred during the 12 h prior to weigh-in, using exercise in a rubberized sweat suit. Weight loss resulted in a reduction in upper body but not lower body strength measures (peak torque and average work per repetition). Anaerobic power and anaerobic capacity were significantly reduced in a dehydrated state (81.4 kgm.s-1, normal weight; 63.9 kgm.s-1, weight loss; 1984.3 kgm.40 s-1, normal weight; 1791.4 kgm.40 s-1, weight loss). Analyses of treadmill data revealed the following: 1) velocity was decreased at LT (4.4%) and peak (6.5%) during weight loss (P less than 0.05); 2) VO2 peak was significantly reduced with weight loss (6.7%, P less than 0.05); 3) treadmill time to exhaustion was significantly reduced in the weight loss state (12.4%) (35.7 min, normal weight; 31.3 min, weight loss). It was concluded that typical wrestling weight loss techniques result in deleterious effects on strength, anaerobic power, anaerobic capacity, the lactate threshold, and aerobic power.

Adolescent↗
PubMed1989

The effects of specificity of training on rating of perceived exertion at the lactate threshold.

To determine the effects of cycle and run training on rating of perceived exertion at the lactate threshold (LT), college men completed a 40-session training program in 10 weeks (n = 6 run training, n = 5 cycle training, n = 5 controls). Pre- and post-training variables were measured during graded exercise tests on both the bicycle ergometer and treadmill. ANOVA on the pre- and post-training difference scores resulted in similar improvements in VO2max for both testing protocols, regardless of training mode. The run training group increased VO2 at the LT by 58.5% on the treadmill protocol and by 20.3% on the cycle ergometer. Cycle trainers increased VO2 LT only during cycle ergometry (+38.7%). No changes were observed in the control group. No differences for RPE at the LT were found before or after training, or between testing protocols for any group. Perception of exercise intensity at the LT ranged from "very light" to "light". The relationship between RPE and %VO2max was altered by the specific mode of training, with trained subjects having a lower RPE at a given %VO2max (no change in RPE at max.). It was concluded that RPE at the LT was not affected by training, despite the fact that after training the LT occurs at a higher work rate and was associated with higher absolute and relative metabolic and cardiorespiratory demands.

Adolescent↗
PubMed1989

Molecular diagnosis of genital human papillomavirus infection: comparison of two methods used to collect exfoliated cervical cells.

Human papillomavirus infection is implicated as an etiologic agent in the development of neoplasia and invasive carcinoma of the cervix. To detect human papillomavirus infection of the cervix, cells must be collected and assayed for human papillomavirus-related deoxyribonucleic acid sequences. Gynecologists and other clinical investigators generally use an exocervical spatula scrape and an endocervical swab for cell collection, analogous to Papanicolaou smear collection. However, inadequate cell recovery is common. To overcome this problem, we have developed the cervicovaginal lavage method for human papillomavirus detection. In the present study we compared the cervicovaginal lavage method with the widely used scrape-swab method in 48 women referred for colposcopic examination. After a Papanicolaou test, two samples were obtained from each woman, either with cervicovaginal lavage followed by scrape-swab or with the scrape-swab followed by cervicovaginal lavage. Human papillomavirus types were assessed by restriction analysis and Southern blot hybridization. In 21 women (44%) test results were positive for human papillomavirus with both the scrape-swab and cervicovaginal lavage cell collection methods; in nine women (19%) test results were positive only with the cervicovaginal lavage method; and in 18 women (38%) results were negative for human papillomavirus with both techniques. None of the women had human papillomavirus detected by scrape-swab without also having it detected with cervicovaginal lavage. The human papillomavirus deoxyribonucleic acid types identified were concordant in the 21 women whose infections were detected with both sampling methods, although the second virus type was detected only with cervicovaginal lavage in one woman who had a mixed genital tract infection. We concluded that cervicovaginal lavage is a more sensitive cell collection method than the scrape-swab technique for assessing human papillomavirus infection of the cervix.

Blotting, Southern↗
PubMed1989

Prediction of lactate threshold and fixed blood lactate concentrations from 3200-m time trial running performance in untrained females.

The present study examined the effectiveness of a 3200-m time trial run for predicting VO2 and running velocity at lactate threshold (LT), and fixed blood lactate concentrations (FBLC) of 2.0, 2.5, and 4.0 mM and peak in untrained women. Thirty-nine female subjects completed a VO2peak/LT test a 3200-m time trial run. Twenty-eight subjects were randomly assigned to a validation sample and the remaining subjects were used for cross-validation purposes. In the validation sample, VO2 measurements at LT, FBLC of 2.0, 2.5, 4.0 mM, and peak were 22.5, 29.2, 31.2, 36.5, and 38.5 ml/kg.min-1, respectively. Velocities at LT, FBLC of 2.0, 2.5, 4.0 mM, and peak were 107.1, 129.7, 136.6, 155.1, and 163.2 m/min, respectively. Regression analysis in the validation group revealed that the 3200-m time trial was an accurate predictor of velocities at LT, FBLC of 2.0, 2.5, 4.0 mM, and peak with correlations of r = 0.70, r = 0.84, r = 0.85, r = 0.87, and r = 0.95, respectively, and standard errors of estimate ranging from +/- 9.5 m/min (for velocity peak) to +/- 13.7 m/min (velocity LT). Vor VO2 prediction, correlations ranged from r = 0.61 (3200-m time vs VO2 LT) to r = 0.77 (3200-m time vs VO2 peak) with the standard errors of estimate ranging from +/- 4.18 (VO2 2.0 mM) to +/- 4.87 ml/kg.min-1 (VO2 4.0 mM).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Percentages of maximal heart rate, heart rate reserve, and VO2peak for determining endurance training intensity in sedentary women.

The use of 60%-95% of maximal heart rate (HR max), heart rate reserve (HRR), and VO2peak as exercise training intensities was examined in sedentary women, and these intensities were related to HR and VO2 observed at the lactate threshold (LT) and fixed blood lactate concentrations of 2.0, 2.5, and 4.0 mM. Thirty-three subjects (means age = 32.5 +/- 3.9 yrs; means ht = 164.2 +2- 5.0 cm; means wt = 67.6 +/- 13.9 kg) completed a VO2/LT treadmill test using a level running protocol. The values at LT, 2.0, 2.5, 4.0 mM, and peak for VO2 were 22.3, 29.0, 31.0, 36.2, and 39.1 ml/kg.min-1, respectively; for velocity were 107.0, 128.9, 135.8, 152.8, and 164.4 m/min, respectively; and for HR were 142.1, 162.9, 169.4, 183.2, and 189.7 bts/min, respectively. The minimum intensity necessary for the majority of subjects to be above LT (n = 17) was 75% HR max while 90% HR max was required for the majority of subjects to be above 2.0 mM (n = 23) and 2.5 mM (n = 19). At 95% HR max 12 subjects were above 4.0 mM. For the majority of subjects to be above LT (n = 18), 55% HRR was necessary; 75%, 85%, and 95% HRR was required for the majority of subjects to be above 2.0 mM (n = 18), 2.5 mM (n = 19), and 4.0 mM (n = 20), respectively. For percent VO2peak, the intensities required for the majority of subjects to be above LT, 2.0 mM, 2.5 mM, and 4.0 mM were 55%, 75%, 80%, and 95% VO2peak, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Generalized equation for predicting body density of women from girth measurements.

This study's purpose was to develop a generalized regression equation to predict body density in adult women. Subjects, 482 women, were hydrostatically weighed and circumference (girths) recorded for thigh, hips (buttocks), iliac, and abdomen (mean of abdomen 1 and abdomen 2). Age (range = 15-79 yr), weight (38.3-132.9 kg), and height (145.5-186.3 cm) were also recorded. Percent body fat ranged from 12.7 to 63.1%. Stepwise multiple regression was used to select the best set of predictors (from seven) of body density. Capitalization on chance was negligible due to the favorable subject to predictor ratio (57 subjects per predictor). The regression equation (N = 400) developed for predicting body density was: body density = 1.168297 - (0.002824 x abdomen) + (0.0000122098 x abdomen2) - (0.000733128 x hips) + (0.000510477 x height) - (0.000216161 x age) [SEE = 0.009486784 (4.2% body fat), R = 0.889, adjusted R2 = 0.787]. Using this equation on a cross-validation sample (N = 82) produced a predicted mean (+/- SD) of 1.016 +/- 0.017 (validation sample mean = 1.016 +/- 0.021) and a total error (SE) of 0.0082 (3.6% body fat). The use of three girth measurements, height, and age enabled us to develop regression equations to predict body density in women that are comparable in accuracy to those using skinfold calipers and, thus, are a viable alternative.

Abdomen↗
PubMed1988

Accurate assessment of body composition in obese females.

Although several generalized regression equations exist for body composition assessment the accuracy of these equations for special populations is uncertain. This study examined the ability to predict body composition variables from girth measurements in obese women. Girth measurements were taken on 156 obese women at abdomen 1 and abdomen 2 (mean value of the two was used), buttocks, and right thigh. Stepwise multiple-regression analysis generated on 110 randomly assigned subjects yielded the following equations: density (g/cc) = -0.00020(mean abdomen) - 0.00032(wt) + 0.00039(ht) + 0.97783 (R = 0.76, SEE = +/- 0.00061); % fat = 0.11077(mean abdomen) - 0.17666(ht) + 0.14354(wt) + 51.03301 (R = 0.76, SEE = +/- 2.9); fat wt (kg) = 0.62039(wt) - 0.17844(ht) + 0.09495(mean abdomen) + 5.88874 (R = 0.96, SEE = +/- 2.9); and lean body wt (kg) = 0.37939(wt) + 0.17898(ht) - 0.09494(mean abdomen) - 6.00423 (R = 0.89, SEE = +/- 3.0). Data from the remaining 46 women were used for cross-validation. These equations were valid, with validity coefficients for fat weight and lean body weight of r = 0.92 (SE = +/- 3.3 kg) and r = 0.86 (SE = +/- 3.3 kg), respectively, with no significant mean differences between actual and predicted values. The use of girth measurements is a simple and practical method of estimating fat weight and lean body weight in obese women.

Adult↗