the number of calories consumed by subject performing an exercise routine is approximated with a computer having a predetermined cycle time during which the distance travelled by the subject is determined . indications of the subject weight , sex and age are entered into a memory of the computer to cause the computer to compute and store an indication of the number of calories the subject burns in traversing a predetermined distance during the computer cycle time . the calories consumed by the subject during the cycle time are calculated from the stored indication and the distance travelled during the cycle time . the indications of calculated consumed calories are accumulated over several consecutive cycle times . to determine distance travelled , signals from a pedometer are combined in the computer with a subject &# 39 ; s stored stride length signal . the pedometer includes a mercury switch having an envelope containing contacts and a mercury globule for selectively wetting and bridging the contacts in response to cyclic motion of the subject . the entire structure is mounted in a watch case .