Rudolph H. Dressendorfer

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 athletes cardiac enlargement differs from most pathologic conditions which have heterogeneous effects on specific cardiac chambers.

Hypozincemia in Runners

Experienced runners were studied to determine the relationship between mileage and zinc levels in the blood. A low animal protein diet may be one factor in zinc depletion.

Increased Morning Heart Rate in Runners: A Valid Sign of Overtraining?

In brief: An elevated resting pulse rate is generally considered a marker of overtraining in endurance athletes who greatly increase their workout distance. This study supports that assumption, demonstrating increased morning heart rates in 12 men who ran twice their regular training mileage during a 500-km (312-mile) road race over 20 days. After the first week of running, morning pulse rates were slightly reduced, but thereafter they progressively increased, becoming 10 beats min(-1) higher (p <.01) as the race ended. Blood pressure, oral temperature, body weight, sweat loss, and blood glucose, lactate, insulin, and Cortisol levels were not related to the increase in morning heart rate.

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.

Physical Training During Pregnancy and Lactation.

Do pregnant or lactating women risk impairing their or their infants health by strenuously exercising? This study adds some interesting insights.

Plasma mineral levels in marathon runners during a 20-day road race

In brief Sports nutritionists generally think an athletes increased mineral requirements can be satisfied by a greater but well-balanced caloric intake. This study supports that concept, demonstrating that 12 male runners who consumed an unrestricted, isocaloric diet maintained normal plasma mineral levels without using mineral supplements during a 500-km (312-mile) road race. None of the nine minerals tested (calcium, phosphorus, sodium, potassium, chloride, magnesium, iron, copper, and zinc) showed tendencies to become persistently reduced over the 20-day period.

The Muscular Overuse Syndrome in Long-Distance Runners

In brief: Indicators of muscular injury from overtraining were studied in 12 male runners during a road race held over 20 days. Dally mileage averaged 17.3 miles per day, twice their regular training distance. Most of the runners reported persistent mild-to-moderate thigh muscle soreness or stiffness. Serum creatine kinase (CK), an enzymatic marker of muscle tissue injury, was elevated on mornings after running but returned to normal values when the runners rested for two days after day 10. Thigh circumference became significantly reduced during the race, suggesting that the unaccustomed high running mileage also produced thigh muscle atrophy.

Fetal Heart Rate Response to Maternal Exercise Testing

Active women are becoming more interested in maintaining physical fitness while pregnant. This preliminary study shows that fetal heart rate responses to maternal exercise are within the normal range.

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

SummaryTo evaulate 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<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.

Physiological Profile of a Masters Runner

A champion middle-distance runner laid off for 44 years, then resumed training and competition at age 70. Physiological tests support the role of genetic endowment in cardiorespiratory fitness.