Ultramarathon Bicycling and the Cardiopulmonary System

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Abstract

The purpose of this study was to investigate the effects of ultramarathon bicycling upon the cardiopulmonary systems of two ultramarathon athletes. These effects were evaluated during the Tandem Transcontinental Record Attempt (TTRA), an attempt to ride a tandem bicycle across the United States in under eight days. The athletes were successful in completing the TTRA in seven days, 14 hours, 55 minutes.

Throughout the TTRA, heart rate, blood pressure, and respiratory gases were intermittently monitored, and pertinent bicycling information regarding cadence, bicycle speed, terrain, temperature, elevation, and wind direction were recorded. Prewaking heart rates and blood pressures were essentially unchanged throughout the TTRA in both athletes. Exercise heart rates decreased in both athletes from highs of 130-170 bpm (mean 150) on Days 1 through 3, to highs of 88-112 bpm (mean 100) thereafter.

Gas analysis from Day 1 to Day 7 of the TTRA revealed (1) a decrease in breathing rate of 32% in one athlete and for both bicyclists; (2) no appreciable change in tidal volume; (3) a 10-35% decrease in minute ventilation; (4) low levels of oxygen consumption (an average of 21.03 and 28.08 ml/min/kg, or 24% and 46% of VO2 max, respectively); (5) a 16-39% decrease in oxygen consumption; (6) no substantial change in ventilatory equivalents; and (7) no noticeable change in the respiratory exchange ratios. Cadence, bicycle speed, terrain, temperature, elevation, and wind direction were taken into consideration when all results were calculated.

This study reveals a decrease in many cardiopulmonary parameters during ultramarathon bicycling which is difficult to interpret in view of a relatively constant workload.

Endurance athletic events which exceed generally accepted durations and/or distances have been termed ultramarathon. Such events have been occurring since the times of ancient Greece, when the hemerodromoi (trained foot couriers) routinely ran distances of 100-300 miles.1 Running was not the only ultramarathon event of the past. From 1763 to 1963, ice skaters raced 120 miles through the 11 cities of Friesland, Netherlands.2 In 1891, the first of the six-day bicycle races took place at Madison Square Garden, New York. Forty individuals started this high-wheeler bicycle affair, riding around a track as far as possible in six days. Six individuals finished with the winner, William “Plugger Bill” Martin, riding 1,466 miles and four laps.3 Today, ultramarathon events such as the Western States 100-Mile Endurance Run in the California Sierra Nevadas, the 750-mile Paris-Brest-Paris bicycle ride, the John Marino Open bicycle races, and the Race Across America are just a few of the many long-distance events which provide individuals an opportunity to test the limits of their physical abilities. The physiologic changes which occur when an individual's limits are pushed to such extremes are just beginning to be understood. Pilot work we have performed suggests that the physiologic changes accompanying ultramarathon bicycling may be due to one or more hypotheses (Table 1).

On May 9, 1987, two ultramarathon bicyclists began the Tandem Transcontinental Record Attempt (TTRA), an attempt to ride a tandem bicycle across the United States in under eight days. The TTRA was successful at 7 days 14 hours 55 minutes. Throughout the TTRA, heart rate, blood pressure, and respiratory gases were intermittently monitored, and pertinent bicycling information regarding cadence, bicycle speed, terrain, temperature, elevation, and wind direction were recorded. The cardiopulmonary changes observed during the TTRA provide a better understanding of the physiological effects of ultramarathoning.

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