Conversion Table for Running on Lower Body Positive Pressure Treadmills

Abstract

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.

Physiological Responses to Treadmill Running With Body Weight Support in Hypoxia Compared With Normoxia

“…Hypoxia induced a rise of ~12 bts . min -1 at all levels of body weight support studied, which though not enough to completely restore the cardiovascular strain observed during non-supported running, may be sufficient to match cardiovascular strain up to a level of 15-20% BWS 10,18 . Our perceptual data indicate that the imposition of hypoxia per se does not increase overall or localised subjective ratings of perceived exertion, at least at the low running speed studied.…”

“…Indeed, a conversion table is now available in order to guide practitioners in their decision making 10 . The reduction in oxygen consumption at 30% BWS within the present investigation are comparable to those observed by Kline et al, (2015; our data 27%, Kline data = 24% decrease in V̇O2).…”

“…A conversion table is now available to help inform decision-making regarding matching the metabolic cost of different speeds (6.4 -16.1km . hr -1 ) and different levels of BWS of 50, 60, 70, 80 and 90% under normoxic conditions 10 .…”

“…Whereas in aging, obese and stroke patients LBPP can facilitate an aerobic stimuli for individuals that would otherwise have difficulty exercising 7 . However with LBPP the metabolic cost of running is reduced, with increasing BWS leading to greater reductions in both V̇O2 and exercising heart rates 6,[8][9][10] . For example, walking with 75% BWS reduced energy expenditure by 45% compared with a non-supported walk 8 .…”

“…For example, walking with 75% BWS reduced energy expenditure by 45% compared with a non-supported walk 8 . However the metabolic cost of running at increasing levels of BWS can be offset by increasing treadmill speed 6,8,10 .…”