ENERGY-COST OF STAIR CLIMBING AND DESCENDING ON THE COLLEGE ALUMNUS QUESTIONNAIRE

In calculating the physical activity index (PAI) on the college alumnu s questionnaire, it is assumed that 8 kcal are expended for every 20 s teps climbed. This value is equal to an energy cost of 0.40 kcal.step( -1). Since it is assumed that subjects climb and descend an equal numb er of stairs, the total value reflects the energy cost of stepping up (estimated at 0.30 kcal.step(-1)) and stepping down (estimated at 0.10 kcal.step(-1)). However, these values appear to be based on theoretic al calculations rather than empirical observation. The purpose of this study was to quantify the energy cost of stair climbing and stair des cending by measuring oxygen uptake. Twenty subjects performed continuo us stair-climbing and stair-descending on an escalator at a stepping r ate of 70 steps.min(-1). Heart rate was monitored by telemetry, and ox ygen uptake was measured by the Douglas bag technique from 5 to 7 min. Results showed that the gross energy cost of stair climbing is 8.6 ME Ts, and that of stair descending is 2.9 METs. Thus, for a 70-kg person the gross caloric costs of ascending stairs (0.15 kcal.step(-1)) and descending stairs (0.05 kcal.step(-1)) are one-half of the values prev iously assumed. In conclusion, the algorithm for calculating PAI on th e college alumnus questionnaire should be modified to reflect a total cost of 0.20 kcal for going up and down one step. Even more precise es timates can be obtained by adjusting for body weight (going up and dow n one flight of stairs requires 1.63 MET.min).