Advertisement
Research Article
‘Whip from the hip’: thigh angular motion, ground contact mechanics, and running speed
Kenneth P. Clark, Christopher R. Meng, David J. Stearne
Biology Open 2020 9: bio053546 doi: 10.1242/bio.053546 Published 21 October 2020

Article Figures & Tables

Figures

  • Fig. 1.
    Fig. 1.

    Thigh angular position versus time for two representative subjects, with dashed regions of the graph indicating the ground contact phase. (A,C) Male recreationally trained athlete at sub-maximal and maximal speeds. (B,D) Male sprinter at sub-maximal and maximal speeds. Faster running speeds were achieved with higher frequencies and greater total amplitudes of thigh angular motion, resulting in greater thigh angular velocities. At top speed, the slope of the angular position versus time curve during ground contact was steeper for the sprinter (D) than for the recreationally trained athlete (C), indicating a greater absolute value of the average angular velocity of the stance thigh during ground contact (ωc). Per Eqn 6, greater ωc was a direct determinant of the faster top running speed attained by the sprinter.

  • Fig. 2.
    Fig. 2.

    Kinematic variables for a single representative subject (male sprinter) across his individual range of speeds. (A) Ground contact time, Tc. (B) Step rate, SR, and step length, SL. (C) Total thigh excursion during ground contact phase, θc, and total thigh excursion from peak extension through peak flexion, θtotal. (D) Average thigh angular velocity during entire gait cycle, ωavg, and lower limb vertical velocity at instant of touchdown (Ankle Vztd).

  • Fig. 3.
    Fig. 3.

    Kinematic variables for all subjects across all speeds (n=154). Best-fit equations and P-values listed here where appropriate, with R2 values presented in accompanying panels. (A) Ground contact time (Tc=0.78x−0.89). (B) Step rate (SR=0.31x+1.58, P<0.0001) and step length (SL=0.72x0.49). (C) Total thigh excursion during ground contact phase (θc=−0.01x2+0.20x+0.22) and total thigh excursion from peak extension through peak flexion (θtotal=0.51x0.56). (D) Average thigh angular velocity during entire gait cycle (ωavg=0.82x−0.08, P<0.0001).

  • Table 1.
  • Table 2.
  • Fig. 4.
    Fig. 4.

    Kinematic variables for all subjects across top speed trials (n=40). Best-fit equations and P-values listed here, with R2 values presented in accompanying panels. (A) Ground contact time (Tc=−0.013x+0.23, P<0.001). (B) Step rate (SR=0.30x+1.78, P<0.0001) and step length (SL=0.10x+1.14, P<0.0001). (C) Total thigh excursion during ground contact phase (θc=−0.03x+1.28, P=0.014) and total thigh excursion from peak extension through peak flexion (θtotal=0.07x+1.03, P<0.001). (D) Average thigh angular velocity during entire gait cycle (ωavg=0.77x+0.58, P<0.0001).

  • Fig. 5.
    Fig. 5.

    Lower limb vertical velocity at instant of touchdown (Ankle Vztd) for all subjects and trials (n=154). Best-fit equations and P-values listed here, with R2 values presented in accompanying panels. (A) Ankle Vztd versus running speed (Ankle Vztd=0.27x−0.02, P<0.0001). (B) Ankle Vztd versus average thigh angular velocity during entire gait cycle (Ankle Vztd=0.33x+0.01 where x is ωavg, P<0.001).

  • Fig. 6.
    Fig. 6.

    Simplified planar representation of the ground contact phase. (A) Geometry of the ground contact leg, including: symmetrical θtd and θto, θc, L0 and Lc. (B) θtd and θto during the ground contact phase. This framework assumes that the leg angle (from ball of foot to hip, θtd or θto in A) is equal to the thigh angle (θtd or θto in B, respectively).

  • Fig. 7.
    Fig. 7.

    Simplified representation of thigh angular motion during the entire gait cycle. This representation assumes symmetrical anti-phase flexion and extension values during ground contact and flight phases. Thigh angular kinematics as a function of time are determined by the parameters of frequency (f=1/T, where T is the period) and amplitude (A). The figures in inset diagrams a–g illustrate the thigh angular position in correspondence with the angular motion presented in the graph. The dashed regions of the graph indicate the ground contact phase, with ωc corresponding to the slope of the angular position versus time curve from touchdown (+0.5 radian) to takeoff (−0.5 radian).

  • Fig. 8.
    Fig. 8.

    Example graphs of thigh angular position versus time for one limb, examining the theoretical effects of altering frequency (f=1/T) and amplitude (A). In A–C, the gray line has f=1.33 Hz and A=0.60 radians. The purple line illustrates the effects on thigh angular velocity that result from altering frequency and amplitude. (A) Increasing A without altering f. (B) Increasing f without altering A. (C) Increasing both A and f. The dashed regions of the graph indicate the ground contact phase, with average ωc corresponding to the slope of the angular position versus time curve. In all three panels, the purple line has greater ωc than the gray line because of increased A and/or f.

Back to top

RSSRSS

Keywords

 Download PDF

Email
Research Article
‘Whip from the hip’: thigh angular motion, ground contact mechanics, and running speed
Kenneth P. Clark, Christopher R. Meng, David J. Stearne
Biology Open 2020 9: bio053546 doi: 10.1242/bio.053546 Published 21 October 2020
del.icio.us logo Digg logo Reddit logo Twitter logo CiteULike logo Facebook logo Google logo Mendeley logo
Citation Tools
Alerts

Article Navigation

Other journals from The Company of Biologists

Advertisement

Biology Open and COVID-19

We are aware that the COVID-19 pandemic is having an unprecedented impact on researchers worldwide. The Editors of all The Company of Biologists’ journals have been considering ways in which we can alleviate concerns that members of our community may have around publishing activities during this time. Read about the actions we are taking at this time.

Please don’t hesitate to contact the Editorial Office if you have any questions or concerns.

2020 at The Company of Biologists

Despite 2020’s challenges, we achieved a lot at The Company of Biologists. In the midst of the pandemic, we have seen long-term projects and new ventures come to fruition. Read our full lowdown of 2020.

Interview- Sebastian Markert

Sebastian Markert is first author of a paper in BiO using C. elegans to model amyotrophic lateral sclerosis. In an interview, he talks about the potential implications of his work and his future plans.

Three communities to support biologists to everywhere

Online communities have never been more important. If you’re looking for somewhere to meet fellow scientists, take part in topical discussions and find virtual events in your field, take a look at each of our community sites:

  • The Node: the community site for and by developmental biologists
  • preLights: the preprint highlights service run by the biological community
  • FocalPlane: the community site for microscopists and biologists alike