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Age and physiological adjustment to continuous, graded treadmill exercise.

Abstract Fifty males, aged 10—65, taking part in the Tecumseh Community Health Study, walked continuously on a treadmill at 3 miles per hour. The grade was increased 3% after 3 min. at each level. Heart rate, ventilation, O2 uptake, and CO2 production were recorded each minute. The purpose of this particular analysis was to determine if a steady state were reached at various grades and if the time required for the acquisition of a steady state was related to age. There was little or no relationship between acquisition of a steady state and age. By the third minute at each level almost all subjects had achieved a plateau or slight decrease in O2 uptake. Carbon dioxide production generally was still increasing during the third minute at each level. Except at the lowest work load, heart rate continued to increase throughout the 3 min. at each level, regardless of age of subject. After the first three work loads, ventilation had not reached a steady state by the third minute, regardless of age of subjects.