title: The fastest runner on artificial legs: different limbs, similar function?
abstract: The recent competitive successes of a bilateral, transtibial amputee sprint runner who races with modern running prostheses has triggered an international controversy regarding the relative function provided by his artificial limbs. Here, we conducted three tests of functional similarity between this amputee sprinter and competitive male runners with intact limbs: the metabolic cost of running, sprinting endurance, and running mechanics. Metabolic and mechanical data, respectively, were acquired via indirect calorimetry and ground reaction force measurements during constant-speed, level treadmill running. First, we found that the mean gross metabolic cost of transport of our amputee sprint subject (174.9 ml O(2)*kg(-1)*km(-1); speeds: 2.5-4.1 m/s) was only 3.8% lower than mean values for intact-limb elite distance runners and 6.7% lower than for subelite distance runners but 17% lower than for intact-limb 400-m specialists [210.6 (SD 13.2) ml O(2)*kg(-1)*km(-1)]. Second, the speeds that our amputee sprinter maintained for six all-out, constant-speed trials to failure (speeds: 6.6-10.8 m/s; durations: 2-90 s) were within 2.2 (SD 0.6)% of those predicted for intact-limb sprinters. Third, at sprinting speeds of 8.0, 9.0, and 10.0 m/s, our amputee subject had longer foot-ground contact times [+14.7 (SD 4.2)%], shorter aerial [-26.4 (SD 9.9)%] and swing times [-15.2 (SD 6.9)%], and lower stance-averaged vertical forces [-19.3 (SD 3.1)%] than intact-limb sprinters [top speeds = 10.8 vs. 10.8 (SD 0.6) m/s]. We conclude that running on modern, lower-limb sprinting prostheses appears to be physiologically similar but mechanically different from running with intact limbs.
authors.affiliation: Locomotor Performance Laboratory, Department of Applied Physiology and Wellness, Southern Methodist University, Dallas, Texas, USA.
authors.forename: Peter G
authors.initials: PG
authors.lastname: Weyand
authors.forename: Matthew W
authors.initials: MW
authors.lastname: Bundle
authors.forename: Craig P
authors.initials: CP
authors.lastname: McGowan
authors.forename: Alena
authors.initials: A
authors.lastname: Grabowski
authors.forename: Mary Beth
authors.initials: MB
authors.lastname: Brown
authors.forename: Rodger
authors.initials: R
authors.lastname: Kram
authors.forename: Hugh
authors.initials: H
authors.lastname: Herr
mesh_terms: D000332:Aerobiosis / Q000502:physiology; D000465:Algorithms; D001186:Artificial Limbs; D001696:Biomechanical Phenomena / Q000502:physiology; D001835:Body Weight / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology; D005684:Gait / Q000502:physiology; D006801:Humans; D007700:Kinetics; D007866:Leg / Q000033:anatomy & histology / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology; D010101:Oxygen Consumption / Q000502:physiology; D010807:Physical Endurance / Q000502:physiology; D012420:Running / Q000502:physiology*