First published online May 5, 2005
Journal of Experimental Biology 208, 1963-1970 (2005)
Published by The Company of Biologists 2005
doi: 10.1242/jeb.01555
Sources of mechanical power for uphill running in humans
Thomas J. Roberts* and
Richard A. Belliveau
Department of Organismic and Evolutionary Biology, Harvard
University, Cambridge, MA 02138, USA
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Fig. 1. Net mechanical work (A), net joint excursion (B), and mean joint moment of
force (C) at the ankle during the stance period for three running inclines.
Values are mean ± S.E.M.
(N=4).
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Fig. 2. Ankle power output (A), angle (B) and moment (C) for stance during level
running (black lines) and running on a 12° incline (red lines). Data are
normalized to the fraction of stance period. Values are mean ±
S.D. for 4 subjects.
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Fig. 3. Net mechanical work (A), net joint excursion (B), and mean joint moment of
force (C) at the knee during the stance period for three running inclines.
Values are mean ± S.E.M.
(N=4).
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Fig. 4. Knee power output (A), angle (B) and moment (C) for stance during level
running (black lines) and running on a 12° incline (red lines). Data are
normalized to the fraction of stance period. Values are mean ±
S.D. for 4 subjects.
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Fig. 5. Net mechanical work (A), net joint excursion (B), and mean joint moment of
force (C) at the hip during the stance period for three running inclines.
Values are mean ± S.E.M.
(N=4).
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Fig. 6. Hip power output (A), angle (B) and moment (C) for stance during level
running (black lines) and running on a 12° incline (red lines). Data are
normalized to the fraction of stance period. Values are mean ±
S.D. for 4 subjects.
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Fig. 7. Average ground reaction force during the stance period for three running
inclines. Values are mean ± S.E.M.
(N=4).
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Fig. 8. The mean hip out-moment arm, R, for force production against the
ground increased as function of running incline. Values are mean ±
S.E.M. (N=4).
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Fig. 9. Ground reaction force-based moments (red) and limb inertia-based moments
(green) compared at the hip for level running. The total moment, calculated
from inverse dynamics (black), is the same given in
Fig. 6. Values are means for 4
subjects, error bars are omitted for clarity.
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Fig. 10. Diagrams of force and limb position at the midpoint of stance for a level
(A) and a 12° incline (B) run. Filled circles indicate the locations of
the centers of rotation of the ankle, knee and hip joints. The resultant
ground reaction force GRF is closely aligned with the hip during level running
(A), resulting in a small out-moment arm (R) and low joint muscle
moment (Mm). During incline running (B), the GRF is
oriented more forward of the hip, increasing R at the hip and
decreasing it at the knee. The increase in R at the hip allows for
higher force and work outputs at the hip during incline running. The decrease
in R at the knee decreases the external moment and limits the
external work that can be done at this joint.
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© The Company of Biologists Ltd 2005
