PubMed Health⌕ Search

Biomedical subjects

R B Cobb

Publications and source records attributed to R B Cobb.

6 recordsLinked to original sources
PubMed1983

Adaptations of forearm circulation to varied intensities and sets of heavy exercise.

Nine male and five female college students were tested on four occasions to determine the effects of various exhaustive weightlifting stimuli on forearm blood flow as measured by strain-gauge plethysmography. Maximum voluntary dynamic wrist curl strength was determined in the first session, which was followed by random treatments of exercise with 70, 80, and 90% of the weight subjects could curl only one time (1 RM) on three separate days. During each treatment, after a 15-min rest, subjects performed three sets of exercise movements at a pace of 0.5 Hz until voluntary exhaustion. Each set of continuous repetitions was followed by a 166-s recovery period. Blood flows (ml flow X 100 ml tissue-1 X min-1) were determined at 10, 36, 62, 88, 114, 140, and 166 s of recovery. Data were analyzed using ANOVA tests for a three (intensities) by three (sets) complete factorial design with repeated measures on all factors. Generally, 90% flows were significantly (P less than 0.05) lower than both 70 and 80% flows. Also, 70% flows were statistically equal to 80% flows. There were significant (P less than 0.05) set effects at 10, 36, 114, and 166 s of recovery. Blood flows for set 3 exceeded those for set 1 at 10, 36, 114, and 166 s of recovery, and blood flows for set 2 exceeded those for set 1 at 166 s of recovery.

Female↗
PubMed1982

Frequency of intensive, prolonged exercise as a determinant of relative coronary circumference index.

This study determined the effects of 10 weeks of intensive swimming 0, 1, 5, and 10 times per week on relative coronary circumference index (RCCI), which was calculated as the ratio of cardiac ventricular weight to the sum of the circumferences of the right and left main coronary arteries. Sixty-nine Wistar rats swam continuously for 30 to 51 min per session while carrying 1.0% to 1.25% of their individual body weights. Hearts were prepared using routine histological methods and were analyzed for RCCI, coronary circumference, heart mass, and regressed heart mass. Data were analyzed for linear, quadratic, and cubic trends relative to exercise frequency. Mean values for wet weight RCCI were 98.82, 99.16, 91.04, and 90.21 mg per planimeter unit for groups exercising 0, 1, 5, and 10 times weekly (P less than 0.01 for linear trend). Regressed mean ventricular dry weights exhibited expected significant linear increases of 4.89%, 5.66%, and 6.12% over sedentary control rats. The RCCI was clearly shown to undergo a significant linearly graded decrease with increasing frequencies of exercise.

Animals↗
PubMed1981

Central ventilatory depression by oral propranolol.

Propranolol, 20 mg, was given orally four times daily for 5 days and placebo four times daily for 5 days in a randomized, double-blind fashion to nine healthy subjects. At the beginning of the study and on the last day of each medication pulse rate, blood pressure, airways resistance, maximum expiratory flow versus volume (using air and using 80% helium and 20% oxygen), spirometry before and after inhaled isoproterenol, and ventilatory and occlusion pressure responses to rebreathing carbon dioxide were measured. Results were compared by the Wilcoxon signed-rank test. Propranolol was associated with decreases in pulse rate (P = 0.002), systolic blood pressure (P = 0.024), and diastolic blood pressure (P = 0.027). There were no differences in airway resistance or the change of expiratory flow with helium-oxygen. Propranolol did not alter the preisoproterenol spirometry values but did reduce the response to isoproterenol. There were decreases in ventilatory responses (P = 0.004) and occlusion pressure responses (P = 0.006) at an end-tidal carbon dioxide of 60 mm Hg. Propranolol's beta-adrenergic blockade suppresses central ventilatory response to carbon dioxide.

Administration, Oral↗