Using a simple rope-pulley system that mechanically couples the arms, legs, and treadmill reduces the metabolic cost of walking

Table 1 Biomechanical and metabolic data for subjects

Variable	Normal mean ± SD	Assisted mean ± SD	% change	n	p
Net metabolic power (W/kg)	3.04 ± 0.58	2.53 ± 0.38	− 16.78*	n = 8	0.001
Gross metabolic power (W/kg)	4.38 ± 0.59	3.87 ± 0.36	− 11.64	n = 8	n/a
Gross V̇O₂ (L/min)	0.921 ± 0.133	0.832 ± 0.156	− 9.67	n = 8	n/a
Normalized (L/min/kg)	0.013 ± 0.002	0.012 ± 0.001	− 7.69	n = 8	n/a
Respiratory exchange ratio	0.85 ± 0.04	0.80 ± 0.06	− 5.88	n = 8	0.077
Stride frequency (Hz)	0.91 ± 0.08	0.90 ± 0.08	− 1.10	n = 8	0.121
Vertical impulse (N·s)	404.47 ± 120.17	404.80 ± 116.13	0.08	n = 8	0.962
Normalized (N·s/BW)	0.5523 ± 0.016	0.5538 ± 0.017	0.27	n = 8	0.842
Braking impulse (N·s)	− 24.55 ± 7.09	− 36.28 ± 12.14	47.78*	n = 8	0.001
Normalized (N·s/BW)	− 0.0337 ± 0.001	-0.0492 ± 0.002	45.99*	n = 8	0.000
Propulsive impulse (N·s)	24.63 ± 7.36	13.53 ± 4.33	− 45.06*	n = 8	0.003
Normalized (N·s/BW)	0.0337 ± 0.001	0.0192 ± 0.002	− 43.03*	n = 8	0.000
Assistive impulse (N·s)	n/a	16.39 ± 10.21	n/a	n = 7	n/a
Normalized (N·s/BW)	n/a	0.0208 ± 0.001	n/a	n = 7	n/a
Peak assistive force (N)	n/a	52.05 ± 21.99	n/a	n = 7	n/a
Normalized (% BW)	n/a	6.93 ± 1.81	n/a	n = 7	n/a

All comparisons were made between normal and assisted walking conditions with significance at P < 0.05. *Signifies significant differences between walking conditions. All comparisons were tested at an alpha level of 0.05 using a two-sided, paired samples t-test. n/a = not applicable

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