Anholm, J. D., Bonjour, S., Brayley, K., Blackburn, R., Conde, J., Eichman, W., Sanders, K., Hughes, W., & Pettis, J. L. (1996). Heart rate profile during prolonged high intensity cycling at low and moderate altitudes. Medicine and Science in Exercise and Sports, 28(5), Supplement abstract 413.

During prolonged constant work-load exercise, heart rate increases along with a decrease in stroke-volume changes and is collectively referred to as "cardiovascular drift." Trained cyclists (N = 20) performed flat and hilly terrain rides at sea-level (450 m) and altitude (2150-3120 m).

It was found that the heart rate response to 3-5 hours of intense exercise at altitude differed from the cardiovascular drift response observed at sea-level.

Implication. The cardiovascular response to prolonged aerobic tasks of trained cyclists is different at altitude than it is at sea-level. This supports the concept of acclimatization specificity.

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