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.