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Biomedical subjects

R H Dressendorfer

Publications and source records attributed to R H Dressendorfer.

At least 19 recordsLinked to original sources
PubMed2006

Effect of resistance training on risk of coronary artery disease in women with multiple sclerosis.

The effects of a lower-extremity progressive resistance-training program (PRT) on risk factors for coronary artery disease (CAD) were determined in patients with multiple sclerosis (MS). Twelve ambulatory women with MS (47.3+/-4.7 years; Expanded Disability Status Score (EDSS), 4.00+/-1.37) completed twice weekly lower-body PRT for 8 weeks. Knee extensor and ankle flexor strength improved significantly (p<0.05) after training, and self-reported fatigue decreased (p<0.05). Serum triglyceride concentrations decreased (p<0.05) but body-weight and fatness, blood pressure, and serum glucose, total cholesterol and high-density lipoprotein cholesterol were unchanged. However, the number of CAD risk factors that reached the clinical threshold for each subject declined after PRT, suggesting that resistance training can promote CAD risk reduction in ambulatory female MS subjects.

Activities of Daily Living↗
PubMed2000

Reversal of runner's bradycardia with training overstress.

OBJECTIVE: To elicit a criterion elevation (> 10%) in resting heart rate (HR) with training overstress, and subsequently test the hypothesis that such "reversed bradycardia" (RB) negatively affects running performance. DESIGN: Prospective before-and-after intervention with a comparison group. SETTING: General community. PARTICIPANTS: 21 healthy male marathon runners. INTERVENTION: Voluntary doubling of training miles on 14 consecutive days. MAIN OUTCOME MEASURES: Left ventricular (LV) function by echocardiography, HR, and plasma epinephrine (PE) at rest and during submaximal exercise, and 15 km road run performance. RESULTS: Two days after the training overstress, 12 runners met the criterion (RB group), showing an average elevation in resting HR of 16% (range: 11 to 23%). The RB group also exhibited hyperkinetic LV shortening (p < 0.05), elevated exercise HR (p < 0.001), increased PE at rest and during exercise (p < 0.05), and reduced 15 km performance (p < 0.05). The other nine runners who maintained a stable resting HR during the intervention showed no significant outcome changes. CONCLUSIONS: In addition to muscular overuse, heightened sympathetic drive likely contributed to the observed reversal of bradycardia. The development of this stress-related cardiac perturbation was associated with a decrement in running performance, confirming the hypothesis.

Adaptation, Physiological↗
PubMed1994

Zinc status and interleukin-1 beta-induced alterations in mineral metabolism in rats.

Changes in zinc (Zn) metabolism and interleukin-1 beta (IL-1 beta) release occur as part of the physiological response to tissue injury and trauma. In the present study, the influence of Zn status on the response to continuous low-dose IL-1 beta administration was evaluated. Rats were fed 50 micrograms Zn/g (adequate zinc; AZn) or 5 micrograms Zn/g (marginal zinc; MZn) diets for 14 days. On day 15, rats were infused via osmotic minipumps, with IL-1 beta (2.3 ng/hr) or saline (control, C) and euthanized 1, 3, or 7 days later. In the AZn rats, IL-1 beta infusion resulted in increased plasma copper (Cu) concentrations and ceruloplasmin (Cp) activity, and decreased iron (Fe) concentrations throughout the 7d period. These effects were most pronounced on d1 and d3. A similar trend was observed in the MZn rats, but IL-1 beta-induced increases in plasma Cu and Cp activity were less than in the AZn fed rats. In MZn and AZn IL-1 beta infused rats, plasma Zn was decreased on Day 1, and Day 3, respectively, compared with their respective controls. AZn IL-1 beta-infused rats were characterized by high liver Fe, Zn, and metallothionein (MT) concentrations on Day 1; by Day 7, only MT concentrations remained elevated. Liver MnSOD activity was 13%-29% higher in both the AZn- and MZn-IL-1 beta-infused rats than their respective controls on Day 3 and Day 7, with most significant increase observed on Day 7. These data show that Zn status can influence the response to low-dose IL-1 beta; this influence of Zn should be considered when IL-1 beta is given therapeutically.

Animals↗
PubMed1991

Acute reduction in maximal oxygen uptake after long-distance running.

Nine male marathon runners, 24 to 39 years of age, were studied during steady state and maximal graded treadmill exercise under control conditions (C) and immediately after a paced outdoor 21.1-km run averaging 89.5 min (E). The half-marathon run and both treadmill trials were performed at 239 +/- 33 m/min. Oxygen uptake (VO2), respiratory exchange ratio (RER), heart rate (HR), plasma lactate concentration (PLa), and rating of perceived exertion (RPE) were measured in the steady state at 0% grade and at the fatigue end point. Compared to C, mean values in E were significantly lower (p less than 0.05) for time to exhaustion (6.0 vs 4.1 min), VO2max (60.0 vs 56.3 ml/kg/min), peak RER (1.18 vs 1.06), and PLa (9.7 vs 7.8 mM/L), whereas maximal HR (184 vs 184 b/min) and peak RPE (19.6 vs 19.9) were not significantly different between trials. Submaximal VO2 during steady-state runs was similar between C and E (44.4 vs 45.0 ml/kg/min; p = NS). Since the attainable VO2max decreased after E, the percentage of VO2max utilized during steady-state runs was higher, averaging 74% in C and 80% in E (p less than 0.05). In the steady state during E, HR (153 vs 161 b/min) and RPE (13.2 vs 14.8) were higher (p less than 0.05), and the increase in PLa from rest (2.7 vs 1.9 mM/L) was lower (p less than 0.05). Submaximal HR during graded exercise in E was 7 to 8 b/min higher (p less than 0.05) at a given VO2, indicating reduced heart rate reserve.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Effects of 7 successive days of unaccustomed prolonged exercise on aerobic performance and tissue damage in fitness joggers.

The effects of 7 successive days of prolonged jogging on aerobic performance and biochemical markers of muscle and red blood cell damage were examined in 10 moderately fit men, ages 27 +/- 2 yr (mean +/- SE). The subjects jogged for 2 h per day at 78 +/- 4% of maximal heart rates and covered a total of 129 +/- 2 km, nearly eight times their regular weekly training distance. At baseline, maximal oxygen uptake (VO2max) during treadmill tests averaged 3.45 +/- 0.24 L/min, or 44.7 +/- 1.4 ml/kg/min. On follow-up tests 2d after the week of increased training, VO2max (3.56 +/- 0.17 L/min) and treadmill performance were not significantly improved. Body weight declined from 79.5 +/- 4.6 kg to 77.8 +/- 4.4 kg (p less than 0.05) because of reduced body fatness (16.8 +/- 2.3% to 13.6 +/- 1.7%, p less than 0.05). Weight-adjusted VO2max increased to 46.4 +/- 2.0 ml/kg/min (p less than 0.05). However, heart rate and systolic blood pressure were not significantly changed at rest, or during submaximal and maximal treadmill exercise. Mean hemoglobin concentration at treadmill testing declined from 14.9 +/- 0.3 g/dl to 13.3 +/- 0.3 g/dl (p less than 0.05). Leg muscle soreness, especially in the thigh region, persisted in all subjects after 3 d. Soreness was accompanied by chronic elevations (p less than 0.05) in serum levels of myoglobin, creatine kinase (CK), lactic dehydrogenase (LD), aminoaspartate, and the isoenzymes CK-MB and LD1,2. Serum haptoglobin levels after jogging fell from 86 +/- 9 mg/dl to 60 +/- 8 mg/dl (p less than 0.05), suggestive of footstrike hemolysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Development of runner's anemia during a 20-day road race: effect of iron supplements.

Intense training for long-distance running has been associated with reduced hemoglobin (Hb) levels and low iron stores. Whether iron supplementation helps prevent this "runner's anemia" remains controversial. To determine the relationship between iron status and the early stage of reduced Hb levels in male runners, we examined hematologic variables in 15 healthy men (ages 25 to 47 yrs) who ran twice their regular training distance in 20 days during a 500-km road race. Nine of the runners took iron-containing tablets which provided an average of 36 mg/d of iron, while the other six did not take iron supplements. Only one of the 15 subjects had a low Hb concentration (less than 14 g/dl) before the race. After 10 days (285 km), low Hb levels (p less than 0.001) were found in 12/15; six of these runners took iron supplements. However, following a 2-day rest period and five more days of running, only 5/15 and 7/15, respectively, had low Hb levels. Serum iron, ferritin, total iron binding capacity, and percent transferrin saturation values remained within normal limits and did not change significantly. Reticulocyte counts progressively increased, becoming 8-fold higher than at baseline (p less than 0.001), irrespective of the use of iron supplements. "Runner's anemia" developed in 11/15 (73%) of the subjects, independently of their iron status and iron intake. The reductions in Hb were accompanied by parallel decreases in RBC count and hematocrit, and by a significant reticulocytosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Effects of a 15-d race on plasma steroid levels and leg muscle fitness in runners.

Effects of increased training distance on resting plasma testosterone and adrenal steroid levels, serum markers of protein catabolism and muscle fiber damage, and field tests of leg muscle fitness were studied in 19 male marathon runners. Data were collected 1-2 d before and 1 d after a 400-km road race over 15 d. The runners maintained their usual training speeds even though the race distance was twice their regular mileage. Testosterone levels decreased 31% (P less than 0.01), from 23.5 +/- 1.7 to 16.2 +/- 1.0 nmol.l-1. The ratio of cortisol to testosterone increased 83% (P less than 0.01). Blood urea nitrogen (BUN) concentration increased from 16.7 +/- 0.7 to 21.8 +/- 1.0 mg.dl-1 (P less than 0.05) and serum total protein decreased from 7.09 +/- 0.10 to 6.88 +/- 0.08 g.dl-1 (P less than 0.05). Serum creatine kinase (CK) activity increased 380%, from 152 +/- 11 to 731 +/- 74 U.l-1 (P less than 0.001) and was associated with persistent leg muscle soreness. There were no significant changes in body weight, estimated lean body weight, hematocrit, or plasma cortisol, aldosterone, progesterone, androstenedione, and DHEA sulfate levels. Test scores for leg power (vertical jump), strength (dead lift), flexibility (sit-and-reach), and speed (timed stands) did not change significantly. The decrease in plasma testosterone did not correlate with the changes in either BUN, total protein, or CK. The results indicate that existent leg muscle fitness was unaltered despite the suppression of circulating testosterone and the development of early protein catabolism and muscular damage.

Adrenal Cortex Hormones↗
PubMed1986

Attenuation of exercise training effects in patients taking beta blockers during early cardiac rehabilitation.

Cardiorespiratory responses to graded treadmill tests administered 1 month after myocardial infarction or coronary bypass surgery and again after 4 weeks of aerobic training were compared in 24 patients taking beta blockers and 15 control patients. There were no significant differences before training between the groups in age, weight, ventricular ejection fraction, oxygen uptake (Vo2) during the fixed work load (1.7 mph/10% grade), Vo2 at the ventilatory threshold, or Vo2max. After training, Vo2max was significantly increased (p less than 0.05) by 16% in the beta-blocker group and by 21% in controls. However, the group taking beta blockers showed no significant change in oxygen pulse (Vo2/heart rate) at the fixed work load or at the ventilatory threshold, whereas the controls increased Vo2/heart rate at the fixed work load by 9% (p less than 0.05) and at the ventilatory threshold by 22% (p less than 0.05). Metabolic and ventilatory responses to submaximal exercise should therefore also be considered when evaluating the efficacy of exercise training in patients taking beta blockers.

Adrenergic beta-Antagonists↗
PubMed1985

Plasma aldosterone and renal function in runners during a 20-day road race.

To evaluate the effects that repeated long-distance running has on plasma aldosterone concentration and urinary excretion of solutes, fifteen male runners were studied during a 20-day, 500-km road race. Venous blood samples were taken on day 1 prior to running, on day 11 after 10 days of running, on day 13 after a 70-h rest, and on day 18 after an additional five days of running. Overnight urine samples were obtained on day 10 before and after running and on days 11, 12, and 13 during the 70-h rest period. Plasma sodium concentrations on days 13 and 18 and plasma potassium concentrations on days 11 and 13 were decreased (P less than 0.05). Plasma aldosterone levels were increased on days 11 and 18 after running and returned to pre-race levels on day 13 after 70 h of rest. Plasma cortisol concentrations were not altered. The urinary excretion rates of sodium were elevated and of aldosterone were decreased after 70 h of rest. Increase in excretion rate of urinary sodium correlated with decrease in concentration of plasma aldosterone. These findings show that plasma aldosterone levels are chronically elevated with repeated long-distance running, resulting in a decrease in urinary excretion rate of sodium.

Adult↗
PubMed1985

Symmetric cardiac enlargement in highly trained endurance athletes: a two-dimensional echocardiographic study.

Twelve highly trained male endurance athletes and 12 normally active matched control subjects were studied by two-dimensional and M-mode echocardiography to evaluate changes in the right and left heart chambers associated with intense aerobic training. Maximal oxygen uptake, a measure of cardiovascular fitness, ranged from 62.1 to 82.6 ml/kg/min in the athletes and from 33.0 to 49.3 ml/kg/min in the control subjects (p less than 0.001). The athletes had significantly greater left ventricular wall thickness (p less than 0.01), left ventricular chamber area (p less than 0.005), left atrial area (p less than 0.01), right ventricular chamber area (p less than 0.002), right ventricular wall thickness (p less than 0.05), and right atrial area (p less than 0.01). Proportionality of cardiac chamber enlargement in the athletes was shown by similar ratios of both right-to-left ventricular areas and right-to-left atrial areas in the two groups. Left ventricular contractility was not significantly different between groups. Cardiac enlargement in endurance athletes enables a greater stroke volume for the performance of sustained, intense exercise; hypertrophy of the chamber walls normalizes wall stress. These changes occur symmetrically in both right and left cardiac chambers in the endurance athlete, reflecting bilateral hemodynamic loading. The symmetry of the endurance athlete's cardiac enlargement differs from most pathologic conditions which have heterogeneous effects on specific cardiac chambers.

Adult↗
PubMed1985

Enlargement of the right heart in the endurance athlete: a two-dimensional echocardiographic study.

M-mode echocardiographic studies of endurance-trained athletes have provided conflicting data for right ventricular (RV) dimensions and no data for right atrial (RA) size. Since two-dimensional echocardiography provides a more accurate measurement of the RV and RA, it was employed together with M-mode echocardiography to evaluate 12 male endurance athletes and 12 sedentary controls matched for body size and age. All subjects were screened by history, physical examination, ECG, and maximal exercise testing. RV and RA areas were planimetered in the apical four-chamber view while displaying maximal chamber sizes. Athletes had significantly greater left ventricular (LV) wall thickness (P less than 0.01), LV area (P less than 0.001), and left atrial (LA) area (P less than 0.01). They also had greater RV area (P less than 0.01), RV wall thickness (P less than or equal to 0.05), and RA area (P less than or equal to 0.01). Maintained proportionality of the cardiac chamber dimensions in the athletes was shown by similar ratios of right-to-left ventricular areas, right-to-left atrial areas, and right-to-left ventricular wall thicknesses in both groups. The symmetry of the greater athlete's heart differs from most pathological conditions which have heterogeneous effects on specific cardiac chambers.

Adult↗
PubMed1982

High-density lipoprotein-cholesterol in marathon runners during a 20-day road race.

Plasma high-density lipoprotein (HDL)-cholesterol and lipid levels were measured in 12 male marathon runners (mean age, 40 years) who ran an average of 28 km/day for ten days, rested 70 hours, then continued to run for eight more days, covering a total distance for both running periods of 500 km. Blood samples were obtained on eight mornings. After one week of running, HDL-cholesterol levels increased 18% and triglyceride levels decreased 22%. However, the three-day rest period reversed these changes. As running resumed, HDL-cholesterol levels again increased and triglyceride levels decreased. There were no significant changes in total cholesterol, body weight, or skinfold thickness despite an average caloric intake of 4,800 kcal/day. Heavy beer drinking had no discernible effect on HDL-cholesterol levels, but may have caused mild hepatic injury as suggested by significantly increased serum alanine transferase and gamma-glutamyl transferase values. This study demonstrates that HDL-cholesterol levels increase with higher running mileage and decrease within days of stopping exercise when caloric and alcohol intake remain elevated.

Adult↗
PubMed1982

Reduction of submaximal exercise myocardial oxygen demand post-walk training program in coronary patients due to improved physical work efficiency.

To assess the effects of walk training on external work efficiency and the determinants of myocardial oxygen demand (MVO2), we measured total somatic oxygen consumption (VO2), heart rate (HR), and systolic blood pressure (SBP) in eight male coronary (CAD) patients during submaximal treadmill walking before and after at least 14 weeks of prescribed exercise. Each patient was tested before and after training at the individually determined horizontal treadmill speed that induced ischemic ST segment depression in the pretraining test. Although maximal oxygen uptake (VO2 max) did not increase significantly with training, submaximal exercise HR and the product of HR and SBP were significantly (p less than 0.05) reduced by 10% (120 leads to 108/min) and 16% (185 X 10(2) leads to 156 X 10(2)), respectively, and none of the patients had ischemic ECG changes after training. The reductions in the cardiac response to exercise were due primarily to a 10% decrease (18.9 leads to 17.1 ml/kg/min, p less than 0.05) in somatic oxygen requirements (VO2), indicating that the patients became more efficient walkers and reduced their MVO2 in proportion to the decreased total VO2. Thus, enhancement of external work efficiency, an extracardiac factor, can lessen myocardial energy costs (MVO2) and thereby raise the exercise threshold for cardiac ischemia in CAD patients even when aerobic capacity (VO2 max) is not increased.

Adult↗