Table 2 Relationship of ACC data to the respective criterion measure (oxygen uptake, mLkgmin) and mean step counts per stage.

	PCC (r)
Activity (VMU/ct·sec-1)	.97 *
Vertical peak (g·sec-1)	.95 *
Mean Step Counts (min-1)	.99 *

A tabular report of validity statistics: Pearson’s Product Correlation Coefficient (PCC) for ACC Vector Magnitude Units (VMU) and Vertical peak output versus oxygen uptake, ml.min.kg.* p < 0.01