Table 1. Physiologic characteristics of 6 elite distance runners on the AlterG® Anti-Gravity treadmill® by velocity and different levels of body weight support. Data are means (±SD).

Variable	8 min·mile–1 (3.35 m·s–1)	pa	7 min·mile–1 (3.84 m·s–1)	p	6 min·mile–1 (4.47 m·s–1)	p	5 min·mile–1 (5.36 m·s–1)	p
VO2 (ml·kg–1·min–1)
0% BWS	35.00 (1.55)		41.35 (1.66)		48.27 (2.03)		59.43 (1.68)
20% BWS	24.30 (2.29)	<.001	28.05 (2.02)	<.001	33.93 (3.16)	<.001	40.96 (4.73)	<.001
40% BWS	23.67 (2.27)	<.001	25.79 (2.42)	<.001	31.31 (3.76)	<.001	37.37 (4.76)	<.001
Test for 20% vs. 40% BWS		.724		.243		.204		.037
Net VO2 (ml·kg–1·min–1)
0% BWS	29.34 (1.85)		35.68 (1.93)		42.60 (1.72)		53.76 (1.51)
20% BWS	19.29 (1.61)	<.001	23.04 (1.89)	<.001	28.38 (3.03)	<.001	35.96 (4.60)	<.001
40% BWS	18.63 (2.15)	<.001	20.75 (2.28)	<.001	26.28 (3.65)	<.001	32.36 (4.64)	<.001
Test for 20% vs. 40% BWS		.433		.086		.028		.536
RER (ratio of VCO2 / VO2)
0% BWS	0.85 (0.07)		0.89 (0.05)		0.91 (0.04)		1.00 (0.02)
20% BWS	0.80 (0.04)	.033	0.88 (0.04)	.478	0.88 (0.03)	.159	0.90 (0.05)	<.001
40% BWS	0.85 (0.06)	.974	0.87 (0.04)	.340	0.87 (0.03)	.097	0.88 (0.03)	<.001
Test for 20% vs. 40% BWS		.045		.779		.746		.471
HR (Beats Per Min)
0% BWS	123.4 (6.2)		134.5 (5.3)		151.8 (6.0)		171.5 (5.6)
20% BWS	105.4 (7.7)	.001	114.5 (8.0)	<.001	126.3 (10.0)	<.001	145.4 (13.7)	<.001
40% BWS	101.4 (12.0)	<.001	107.3 (10.1)	<.001	117.9 (10.6)	<.001	133.9 (12.2)	<.001
Test for 20% vs. 40% BWS		.484		.207		.138		.035
RPE (6-20)
0% BWS	9.3 (1.9)		11.7 (2.0)		14.3 (1.4)		16.8 (1.5)
20% BWS	8.3 (1.2)	.251	10.0 (2.0)	.058	12.3 (1.4)	.024	14.3 (1.2)	.005
40% BWS	7.3 (1.0)	.024	9.2 (1.5)	.005	12.0 (1.3)	.009	14.2 (1.3)	.003
Test for 20% vs. 40% BWS		.251		.338		.700		.847