Ambulatory estimates of maximal aerobic power from foot -ground contact times and heart rates in running humans

Seeking to develop a simple ambulatory test of maximal aerobic power (V˙o 2 max), we hypothesized that the ratio of inverse foot-ground contact time (1/ t c) to heart rate (HR) during steady-speed running would accurately predictV˙o 2 max. Given the direct relationship between 1/ t c and mass-specific O2uptake during running, the ratio 1/ t c · HR should reflect mass-specific O2 pulse and, in turn, aerobic power. We divided 36 volunteers into matched experimental and validation groups.V˙o 2 max was determined by a treadmill test to volitional fatigue. Ambulatory monitors on the shoe and chest recorded foot-ground contact time ( t c) and steady-state HR, respectively, at a series of submaximal running speeds. In the experimental group, aerobic fitness index (1/ t c · HR) was nearly constant across running speed and correlated withV˙o 2 max ( r = 0.90). The regression equation derived from data from the experimental group predicted V˙o 2 max from the 1/ t c · HR values in the validation group within 8.3% and 4.7 ml O2 · kg−1 · min−1( r = 0.84) of measured values. We conclude that simultaneous measurements of foot-ground constant times and heart rates during level running at a freely chosen constant speed can provide accurate estimates of maximal aerobic power.