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 ver dot O-2 (max)), we hypothesized that the ratio of inverse foot-ground c ontact time (1/t(c)) to heart rate (HR) during steady-speed running would a ccurately predict (V) over dot O-2 (max). Given the direct relationship bet ween 1/t(c) and mass-specific O-2 uptake during running, the ratio 1/t(c).H R should reflect mass-specific O-2 pulse and, in turn, aerobic power. We di vided 36 volunteers into matched experimental and validation groups. (V) ov er dot 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 runnin g speeds. In the experimental group, aerobic fitness index (1/t(c).HR) was nearly constant across running speed and correlated with (V) over dot O-2 ( max) (r = 0.90). The regression equation derived from data from the experim ental group predicted (V) over dot O-2 (max) from the 1/t(c).HR values in t he validation group within 8.3% and 4.7 ml O-2.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 con stant speed can provide accurate estimates of maximal aerobic power.