Conversion table for running on lower body positive pressure treadmills

Lower body positive pressure (LBPP) or antigravity treadmills are becoming increasingly popular in sports and rehabilitation settings. Running at a decreased body weight (BW) reduces metabolic cost, which can be offset by running at faster speeds. To date, however, little is known about how much faster someone must run to offset the reduced metabolic cost. This study aimed to develop a user-friendly conversion table showing the speeds required on an LBPP treadmill to match the equivalent metabolic output on a regular, non-LBPP, treadmill across a range of body weight supports. A total of 20 recreational runners (11 males, 9 females) ran multiple 3-minute intervals on a regular treadmill and then on an LBPP treadmill at 6 different BWs (50-100%, 10% increments). Metabolic outputs were recorded and matched between the regular and LBPP treadmill sessions. Using regression analyses, a conversion table was successfully created for the speeds from 6.4 to 16.1 km·h (4 to 10 mph) in 0.8 km·h (0.5 mph) increments on the regular treadmill and BW proportions of 50, 60, 70, 80, 90, and 100% on an LBPP treadmill. The table showed that a greater increase in speed on the LBPP treadmill was needed with more support (p < 0.001) but that the proportion increase was smaller at higher speeds (p < 0.001). This research has implications for coaches or practitioners using or prescribing training on an LBPP treadmill.