Inheritance of a cardiac arterial asymmetry in mice.

A pair of coronary arteries supplies the interventricular septum of the heart of Mus musculus. The members of this pair tend to be of unequal size, which permits distiniction between specimens displaying left asymmetry and those showing righit asymmetry. Three inbred strains (C57BL/1O, DBA/1, and Bulb/c) differ with regard to this asymmetry. However, variation exists within strains, which suggests that nongenetic factors also influence the development of the asymmetry. Right arterial asymmetry is dominant over left asymmetry.

Effect of long-term moderate physical exercise on plasma lipoproteins. The National Exercise and Heart Disease Project.

As part of the National Exercise and Heart Disease Project, 223 postcoronary men, aged 30 to 64, were randomly assigned to moderate exercise or control groups. Levels of total plasma cholesterol, high- and low-density lipoprotein (HDL and LDL) cholesterol, and triglycerides were measured. At baseline, alcohol intake, weight, and skin-fold thickness but not treadmill work capacity correlated with triglyceride or HDL cholesterol levels. After one year, no clinically important change in lipid levels was observed in either group. Using multiple regression analysis of the combined groups, changes in several independent variables, including work capacity change, were not predictive of changes in lipid levels. Thus, changes in levels of fitness and/or regular exercise did not substantially influence HDL cholesterol or other lipid levels.

Exercise conditioning and cardiopulmonary fitness in cystic fibrosis. The effects of a three-month supervised running program.

Exercise intolerance is common in cystic fibrosis (CF). We examined the effects of a supervised three-month running program on exercise tolerance, pulmonary function, cardiorespiratory fitness (peak oxygen consumption), and respiratory muscle endurance in CF patients. We studied 31 patients, 21 exercise and ten control, aged 10 to 30 years, with pulmonary involvement ranging from mild to severe. The exercise and control groups were not significantly different with respect to age, sex, pulmonary function, exercise tolerance, or cardiorespiratory fitness. After three months of physical conditioning, the exercise group had significantly increased exercise tolerance and peak oxygen consumption and significantly lower heart rates for submaximal work loads, while the nonexercising (control) group was unchanged in all these variables. The FEV1 decreased significantly in the control group. There were no other significant changes in pulmonary function in either the control or exercise group. Respiratory muscle endurance increased significantly in the exercise patients, and did not change in the control patients. There were no adverse effects of the program. The data suggest that a supervised running program can increase CF patients' exercise tolerance and cardiorespiratory fitness, perhaps in part by increasing respiratory muscle tolerance. The effects of a much longer program deserve study.

Limitations of marathon running in the rehabilitation of coronary patients: anatomic and physiologic determinants.

Prescribed, supervised exercise training has proved valuable in the rehabilitation of selected coronary patients. However, long distance (marathon) running has limited cardiovascular value in the rehabilitation of patients for a majority of occupations, which involve predominantly upper extremity effort. The age of patients with coronary heart disease and the severity of the lesions preclude the wide application of marathon running to the general coronary heart disease population. Less than 6/1000 subjects with coronary heart disease have been estimated as potentially being able to achieve by high-level training a maximum Vo2 sufficient to complete a marathon race in 5 hours. The hazards of high-level-activity-induced cardiac arrest that is reversible mandates the availability of CPR equipment and personnel in the immediate vicinity of all coronary patients and most coronary-prone patients who are undertaking such heroic activity. Over-publicized marathon running by a few subjects has aroused unrealistic expectations for the majority of coronary heart disease subjects and probably similarly for a considerable number of coronary-prone subjects, many of whom have "silent" coronary disease.

Umbilical artery waveform during bicycle exercise in normal pregnancy.

Eighteen healthy pregnant women in the last half of gestation exercised to 85% of their predicted maximum heart rate on a bicycle ergometer. Pulsed Doppler flow studies before the exercise and during the recovery period were taken close to the umbilical artery's placental insertion site. The systolic-to-diastolic ratio (S/D) of the umbilical artery waveform did not change significantly during the period of observation. In three women, however, a significant increase in the S/D ratio occurred in the first few minutes post-exercise; this was due to a transient fetal bradycardia. In one woman, the S/D ratio remained high despite return of a normal fetal heart rate.

Evaluating the cardiac patient for exercise therapy. Role of exercise testing.

Several types of exercise tests and their use are reviewed. Suggestions are made for modification of tests to enhance their value in the counseling of normal individuals and patients with cardiac problems regarding occupational, recreational, and training activity. Also discussed are indications and contraindications to testing, end points in testing, and evaluation of test results.

Benefits of Arm Exercise in Cardiac Rehabilitation.

Knowing the importance of arm exercise as well as leg exercise, and the physiological benefits of both, can aid the physician in designing a rehabilitation program for cardiac patients.

Characteristics of National-Class Race Walkers.

In brief: Physiological and selected Psychological characteristics of nine highly trained race walkers were studied and the results compared to those for distance runners and other athletes of similar age. The percent body fat of the race walkers was similar to or lower than the other athletes. Their VO2 max of 62.9 ml· kg(-1)· min(-1) was significantly higher than active men of comparable age and similar to or higher than many athletes, but significantly lower than world-class endurance athletes.