Oxygen consumption and heart rate in different modes of manual postal delivery

Abstract

Oxygen consumption ([Vdot]O₂) and heart rate (HR) was measured in eleven healthy men (mean age 34·5 years) during five modes of simulated postal delivery: on level ground by foot, bicycle and push-cart, and on stairs by foot and push-cart. HR was measured telemetrically and samples of expired air were collected with a Kofranyi-Michaelis gas meter. Each delivery mode was performed twice; at the standard pace recommended by the postal authorities and at a free pace. [Vdot]O₂ and relative aerobic strain (RAS) were in the same level in on-foot and cart delivery but HR was lower in cart than in on-foot delivery. In bicycle delivery [Vdot]O₂, RAS and HR were on the same level as in stairs/on-foot and stairs/with cart delivery but significantly higher than in on-foot and cart delivery on level ground. For all delivery modes the free pace resulted in significantly higher physiological stress and strain than the standard pace. The mean values of the different delivery modes varied from 1·0 to 1·71/min for [Vdot]O₂, from 30·6 to 54·3% for RAS and from 104 to 136 beats/min for HR. On the basis of these results maximal allowable delivery times (hr/day) were proposed with respect to age, sex, delivery mode and delivery pace.

Keywords:

• Allowable work time
• Heavy work
• Strain
• Stress
• Work method