PubMed Health⌕ Search

Biomedical subjects

A D Rogol

Publications and source records attributed to A D Rogol.

At least 19 recordsLinked to original sources
PubMed1992

Exercise training at and above the lactate threshold in previously untrained women.

We examined the effects of training at and above the lactate threshold in previously untrained women. Twenty-four untrained eumenorrheic women (age = 31.3 +/- 4.0 yrs, wt = 66.2 +/- 7.6 kg, ht = 166.4 +/- 5.8 cm) were assessed at baseline [during days 1-3 of the menstrual cycle (MC)] and every 4 MC after that (for 1 year) for VO2 and velocity (V) at LT, fixed blood lactate concentrations (FBLC) of 2.0, 2.5, and 4.0 mM, and Max. Subjects were assigned to control (C, n = 7), at LT/LT, trained 6 days/week at the velocity associated with LT, (n = 9) or above LT (greater than LT, trained 3 days/week at the velocity midway between V LT and V Max and 3 days/week at V LT, n = 8) groups. Exercise prescriptions were adjusted after each assessment and each group progressed similarly in weekly mileage. No between group differences were observed before training. After training the greater than LT group had significantly higher values than the C and /LT groups for LT (p less than 0.05). For FBLC of 2.0, 2.5, and 4.0 mM and Max, the greater than LT group values were greater than the C group (p less than 0.05). No differences were observed after training between the /LT and C groups. Although the greater than LT group had higher VO2 and V Max values than the /LT group after training, these differences were not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

The effect of training intensity on ratings of perceived exertion.

We examined the effects of intensity of training on ratings of perceived exertion (RPE) at the lactate threshold (LT), fixed blood lactate concentrations (FBLC) of 2.0, 2.5 and 4.0 mM and peak in 25 untrained eumenorrheic women (mean +/- SD: age = 30.9 +/- 4.1 yrs; height = 165.7 +/- 5.9 cm; weight = 65.5 +/- 7.6 kg) who completed one year of run training. Subjects were recruited as sedentary controls or were randomly assigned to one of two training groups: 1) at the lactate threshold (at LT) or 2) above the lactate threshold (greater than LT). The at LT group trained at velocity LT and the greater than LT group trained at the velocity midway between velocity LT and peak velocity. Training subjects were reevaluated every fourth menstrual cycle and training intensity was adjusted. The control group was reassessed at menstrual cycle 12. Before training no among group differences were observed for VO2 or velocity at LT, FBLC and peak. Both training groups increased VO2 at LT, FBLC and peak as a result of training (p less than 0.05), with the greater than LT group exhibiting greater improvement than the at LT group (VO2 at LT, FBLC of 2.0, 2.5 and 4.0 mM and peak increased by 6.4, 5.3, 5.1, 4.0 and 4.7 ml/kg.min-1 for at LT and by 10.4, 9.2, 8.6, 5.1 and 5.9 ml/kg.min-1 for greater than LT; p less than 0.05). Similar findings were observed for the velocity associated with these lactate concentrations. No pre/post differences were observed in VO2 or velocity for the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Dietary patterns, eating behaviors, and bone mineral density in women runners.

Although reduced gonadal steroid hormone concentrations appear to play a major role in lower trabecular bone mineral density (BMD) in women with athletic amenorrhea, dietary deficiencies and eating behaviors may also affect BMD in women runners. To investigate this possibility, dietary patterns (7-d records), eating-disorders inventory (EDI), and BMD were examined in nine nonrunning eumenorrheic control (Contl) and 32 women runners classified as eumenorrheic (n = 19, Eumen) and oligo/amenorrheic (a group in which some were oligomenorrheic and some were amenorrheic; Ol/Am, n = 13). Runner groups had similar cardiorespiratory fitness, body composition, and training characteristics. Lumbar spine BMD was lower in the Ol/Am runners (-12%, P less than 0.05) but proximal femur BMD did not differ. Dietary intake and EDI subscale scores were similar among the groups. However, there was an inverse trend between EDI subscale scores for bulimia and ineffectiveness and femoral BMD in the Ol/Am runners (r = -0.62 to -0.71, P less than 0.05). These results suggest that self-reported dietary intake and/or eating behaviors do not predict reproductive-function alterations in women runners, but eating behaviors may be associated with lower BMD in Ol/Am runners.

Adolescent↗
PubMed1992

Durability of the reproductive axis in eumenorrheic women during 1 yr of endurance training.

Menstrual cycle (MC) alterations occur in some endurance-training women. We hypothesized that a prospective running program would evoke alterations in MC phase lengths and in the physiological frequency of pulses of luteinizing hormone (LH) and/or diminish 24-h integrated serum LH concentrations in some women. In addition, we postulated that women who train more intensively (above the lactate threshold) would show alterations in gonadotropin release earlier in the training program or to a greater degree. To test these hypotheses, we examined the effects of different exercise intensities on physiological and endocrine responses. Twenty-three healthy eumenorrheic gynecologically mature (postmenarchal age 17.8 +/- 0.9 yr) untrained women undertook a 1-yr training program at one of two exercise intensities, one at a velocity corresponding to the lactate threshold (LT) and the other halfway between that of LT and peak running velocity, or served as controls. Training distance was the same in each exercise group. Physiological measurements were repeated every four MC to track changes in fitness and readjust training velocities. The lengths of the MC and the follicular and luteal phases were determined from hormonal concentrations. Body composition, nutritional intake, and pulsatile release of LH were determined. The women ran approximately 790 miles. Each group improved physiologically, with the greater than LT group improving to a greater degree. A less than 2-day decrease in the luteal phase length was observed only in the greater than LT group. No significant changes for any parameter of pulsatile LH release were noted between exercise groups. No significant changes in nutritional intake and only small changes in body composition were noted in either exercise group despite the added energy expenditure of exercise. We conclude that a progressive exercise program of moderate distance and intensity does not adversely affect the robust reproductive system of gynecologically mature eumenorrheic women.

Adult↗
PubMed1992

Reproductive hormones and bone mineral density in women runners.

We examined the relationships among reproductive hormone concentrations and bone mineral density (BMD) in 43 women runners classified as eumenorrheic (n = 24), oligomenorrheic (n = 8), or amenorrheic (n = 11). Results were compared with a eumenorrheic nonrunner control group (n = 11). Serum 17 beta-estradiol, progesterone, and dehydroepiandrosterone sulfate concentrations were determined in daily blood samples for 21 days, and integrated concentrations (areas under the curve) were calculated. BMD was assessed at the lumbar spine and proximal femur by dual-photon absorptiometry. As expected, 17 beta-estradiol, progesterone, and lumbar spine BMD were higher in the control and eumenorrheic runner groups than in the oligomenorrheic and amenorrheic runner groups (P less than 0.05). Progesterone concentration was significantly correlated with lumbar spine BMD in the eumenorrheic runners (r = 0.61). None of the steroid hormones was significantly related to BMD in the oligomenorrheic/amenorrheic group. The present data suggest that circulating levels of gonadal steroid hormones affect axial BMD in eumenorrheic runners.

Adolescent↗
PubMed1992

Endurance training amplifies the pulsatile release of growth hormone: effects of training intensity.

The effects of intensity of run training on the pulsatile release of growth hormone (GH) were investigated in 21 eumenorrheic untrained women. The O2 consumption (VO2) at the lactate threshold (LT); fixed blood lactate concentrations (FBLC) of 2.0, 2.5, and 4.0 mM; peak VO2; maximal VO2; body composition; and pulsatile release of GH were measured. Subjects in both the at-lactate threshold (/LT, n = 9) and above-lactate threshold (greater than LT, n = 7) training groups increased VO2 at LT and FBLC of 2.0, 2.5, and 4.0 mM and VO2max after 1 yr of run training. However, the increase observed in the greater than LT group was greater than that in the /LT group (P less than 0.05). No change was observed for the control group (n = 5). No among- or within-group differences were observed for body weight, although trends for reductions in percent body fat (P less than 0.06) and fat weight (P less than 0.15) were observed in the greater than LT group, and both training groups significantly increased fat-free weight (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Exogenous androgen does not alter hypothalamic proopiomelanocortin gene transcript levels in the sexually immature male rat.

To investigate possible mechanisms whereby the augmentation of hypothalamic proopiomelanocortin (POMC) messenger ribonucleic acid (mRNA) levels occurs with pubertal development, we employed the techniques of testosterone administration and in situ hybridization histochemistry in sexually immature male rats. Six animals from each of the following groups were studied: (1) untreated controls (CTRL); (2) empty capsule (SHAM); (3) testosterone capsule (TEST), and (4) untreated adults (ADLT). Capsules were implanted at 21 days of age. Groups 1-3 were sacrificed at 35 days of life; group 4 at 55 days. Ventral prostate and seminal vesicle weights were obtained to assess the biologic effect of testosterone. Hybridizations were performed on coronal brain slices through the region of the arcuate nucleus using a 35S-labeled oligonucleotide probe complementary to a 30-base sequence within POMC mRNA. Anatomically matched tissue sections (11 per animal, from the retrochiasmatic region rostrally to the premammillary nucleus caudally) were exposed to x-ray film, followed by densitometric analysis. The mean serum testosterone concentration of the TEST group was significantly greater than that of the ADLT animals; values for the CTRL and SHAM rats were undetectable. The accessory sex organ weights of the ADLT animals were greater than those of the TEST rats; both values were greater than those of the CTRL and SHAM groups which were indistinguishable. Increased levels of hypothalamic POMC mRNA were observed in the male rat after pubertal development.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Elevated growth hormone secretory rate in premature infants: deconvolution analysis of pulsatile growth hormone secretion in the neonate.

Premature infants have higher circulating concentrations of growth hormone (GH) than term infants. Previous investigations of these differences have used sampling frequencies of every 30 min with subsequent application of pulse detection algorithms, such as the CLUSTER program, to assess serum GH pulse parameters. To determine differences in GH secretory rates or GH t1/2 values between premature and term infants, we have sampled 11 neonates at 15-min intervals. We performed deconvolution analysis of the resultant plasma GH values to estimate GH secretory and clearance parameters. Five premature infants (gestational age range 24-34 wk) and six term infants (gestational age range 38-42 wk) were sampled every 15 min for 6 h. All subjects had indwelling arterial catheters. GH was measured (in duplicate) by RIA using 10 microL of plasma. Premature infants had higher secretory burst amplitudes (2.2 +/- 0.13 micrograms/L/min versus 1.4 +/- 0.27 micrograms/L/min, p = 0.02), higher production rates (product of the total number of bursts and the mean mass of GH secreted per burst, 811 +/- 173 micrograms/L/6 h versus 283 +/- 77 micrograms/L/6 h, p = 0.03), and a higher mass of GH per secretory burst (106 +/- 25 micrograms/L versus 38 +/- 11 micrograms/L, p = 0.049) than term infants. The integrated plasma GH concentration exhibited a strong trend toward a higher value in the premature infants (18,100 +/- 800 micrograms/L versus 10,200 +/- 2,700 micrograms/L, p = 0.067).(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗
PubMed1992

Endogenous growth hormone secretion and clearance rates in normal boys, as determined by deconvolution analysis: relationship to age, pubertal status, and body mass.

Mean plasma GH concentrations increase in normal boys during mid- to late-puberty. To investigate the nature of the pituitary secretory events and/or altered metabolic clearance responsible for these serum GH concentration changes, we performed multiple-parameter deconvolution analysis of 46 24-h serum GH concentration-time series obtained from normal boys at various stages of puberty and young adulthood. The subjects ranged in chronological age from 7-27 yr. The height and weight of each subject were between the 5th and 95th percentile for age. The calculated daily mass of GH secreted was greatest (P less than 0.001) in late pubertal boys (mean +/- SE, 1810 +/- 250 micrograms/24 h) and was triple the value in prepubertal boys (610 +/- 65 micrograms/24 h). When the values were normalized and expressed as mass of GH secreted per unit (m2) body surface area or per L distribution volume, GH secretion in late pubertal boys was still significantly greater than that in any other group (P less than 0.05). These values for late pubertal boys were nearly double the corresponding values for prepubertal boys (1160 +/- 160 vs. 600 +/- 58 micrograms GH/m2.24 h and 440 +/- 63 vs. 270 +/- 25 micrograms GH/L vol.24 h, respectively). When the effect of clearance mechanics on serum GH concentrations was removed mathematically, the primary change in predicted GH secretory burst parameters during pubertal development was an increase in GH mass released per burst resulting from an increase in the maximal rate of GH secretion attained within the bursts. These changes in the amplitude of GH release events were specific, in that they were largely independent of any accompanying alterations in duration or frequency of the GH secretory bursts or in serum GH half-life. Correlation analysis revealed that the 24-h GH secretion rate varied inversely with the subjects' body mass index SD score (r = -0.65; P less than 0.01), suggesting that differences in body mass, even within the normal range, contribute to the wide variability in daily GH secretion rates among normally growing children. The plasma insulin-like growth factor-I concentrations of all subjects correlated positively with the calculated 24-h GH secretion rate (r = 0.51; P less than 0.001). In summary, the primary neuroendocrine alteration responsible for the augmented serum GH concentrations characterizing mid- to late-puberty in boys is an increased mass of GH released per pituitary secretory episode resulting from an increased maximal rate of GH secretion within each burst.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1992

Properties of spontaneous growth hormone secretory bursts and half-life of endogenous growth hormone in boys with idiopathic short stature. Genentech Collaborative Group.

We analyzed endogenous GH secretory dynamics and MCRs by a novel quantitative deconvolution technique in 20 boys with idiopathic short stature (ISS) and 35 boys of normal stature in Tanner stage I of puberty. We tested the null hypotheses that 1) ISS is not associated with any alterations in the frequency, mass, amplitude, or duration of spontaneous GH secretory bursts and/or the 24-h GH production rate; and 2) the half-life of endogenous GH is not altered in ISS. The boys with ISS had a mean (+/- SEM) bone age of 8.0 +/- 0.42 yr and a chronological age of 10 +/- 0.50 yr. The latter was similar to the chronological (and bone) age of the normal boys of 9.8 +/- 0.23 (and 9.3 +/- 0.34) yr. Mean height SD scores were significantly lower in ISS boys, viz. -2.7 +/- 0.15 in ISS vs. +0.34 +/- 0.13 in normal boys (P less than 0.001). Plasma insulin-like growth factor-I concentrations were similar in the two groups, as were (24-h) mean serum GH concentrations, viz. 3.5 +/- 0.29 micrograms/L in ISS and 4.1 +/- 0.49 micrograms/L in normal boys (P = NS). Deconvolution analysis revealed that the mean number of GH secretory events per 24 h was similar in normal and ISS boys, viz. 9.6 +/- 0.76 (normal) vs. 8.4 +/- 0.55 (ISS), and that there was no significant difference in mean GH interburst intervals. The amplitude, mass, and duration of computer-resolved GH secretory bursts also did not differ in normal and ISS boys. The half-lives of endogenous GH were estimated to be 16 +/- 0.77 min in the ISS and 18 +/- 0.93 min in the control boys (P = NS). The calculated daily GH secretion rate per unit distribution volume was not significantly reduced in ISS, i.e. 194 +/- 19 micrograms/L.day in ISS vs. 177 +/- 19 micrograms/L.day in control boys. Moreover, daily GH secretion rates corrected for body mass index (weight/height2) in the twp groups were not significantly different. In summary, the present cohort of boys with ISS manifested no significant alterations in GH secretory burst frequency, duration, mass, or amplitude or in the half-life of endogenous GH compared to normal boys in Tanner stage I of pubertal development. Indeed, whether daily GH secretion rates are expressed per unit distribution volume or per unit body mass index, groups of boys with ISS and normal height controls secrete similar total amounts of GH. We conclude that the overall dynamics of GH secretion and clearance in boys with ISS considered as a whole cannot be distinguished readily from physiological patterns observed in prepubertal boys of normal height.

Adolescent↗
PubMed1992

Anabolic-androgenic steroids and the adolescent.

This article has reviewed some of the hormonal and behavioral maturation that occurs during adolescence, which are characterized by remarkable physical changes and behavioral vulnerability. Risk taking of many varieties is common and drugs (including anabolic-androgenic steroids) form a part of the prevailing culture in many places. These steroids probably are not severe health hazards when taken intermittently and in low to moderate doses. The 17-alkylated derivatives are clearly the more likely to cause hepatotoxicity. Thus, the scare tactics formerly used (severe constitutional side effects) are doomed to failure. The tenuous link between these drugs and objective behavioral and addictive effects must be strengthened before health strategies based on this issue can be validated. Clearly, the lack of scientific information has impeded, if not precluded, the formulation of an effective health education strategy. The most potent deterrent to the use of steroid drugs by athletes must be the moral issue of fair play and maintaining a "level playing field." We strongly support directed research in these areas and hope that the credibility of the scientific community can be regained after its faulted "stop steroid use" campaigns based on the lack of steroid efficacy in bringing about desired results or on their dire consequences have been replaced with credible evidence to refute their use on these and other grounds.

Adolescent↗
PubMed1992

Long-term endurance training alters the hypothalamic-pituitary axes for gonadotropins and growth hormone.

In a prospective fashion we have studied the impact of chronic exercise of two intensities on the hypothalamic-pituitary-end organ axes for gonadotropins and GH in gynecologically mature, previously sedentary women. Physiologic alterations are evident in both axes with a doubling of 24-hour mean serum GH concentrations at 1 year and smaller, transient changes in pulsatile LH release during the first four menstrual cycles. The latter period of physiologic adaptation should be studied more intensively with more frequent exercise evaluation. Perhaps more significant "adaptation to stress" would be quantitated. We also emphasize that gynecologically less mature women were not studied and only the early follicular phase was evaluated. Adaptive changes of greater magnitude (including amenorrhea) might have been produced if a different group of women, a markedly different training regimen, or a different phase of the menstrual cycle were studied. Finally, whether or not they participate in physical training, younger amenorrheic women are at increased risk for diminished lumbar spine bone mineral content and skeletal fractures.

Exercise↗