Advertisement
Journal Articles
Exploring dynamic similarity in human running using simulated reduced gravity
J.M. Donelan, R. Kram
Journal of Experimental Biology 2000 203: 2405-2415;

Summary

The Froude number (a ratio of inertial to gravitational forces) predicts the occurrence of dynamic similarity in legged animals over a wide range of sizes and velocities for both walking and running gaits at Earth gravity. This is puzzling because the Froude number ignores elastic forces that are crucial for understanding running gaits. We used simulated reduced gravity as a tool for exploring dynamic similarity in human running. We simulated reduced gravity by applying a nearly constant upward force to the torsos of our subjects while they ran on a treadmill. We found that at equal Froude numbers, achieved through different combinations of velocity and levels of gravity, our subjects did not run in a dynamically similar manner. Thus, the inertial and gravitational forces that comprise the Froude number were not sufficient to characterize running in reduced gravity. Further, two dimensionless numbers that incorporate elastic forces, the Groucho number and the vertical Strouhal number, also failed to predict dynamic similarity in reduced-gravity running. To better understand the separate effects of velocity and gravity, we also studied running mechanics at fixed absolute velocities under different levels of gravity. The effects of velocity and gravity on the requirements of dynamic similarity differed in both magnitude and direction, indicating that there are no two velocity and gravity combinations at which humans will prefer to run in a dynamically similar manner. A comparison of walking and running results demonstrated that reduced gravity had different effects on the mechanics of each gait. This suggests that a single unifying hypothesis for the effects of size, velocity and gravity on both walking and running gaits will not be successful.

REFERENCES

    1. Alexander, R. McN
    (1989). Optimization and gaits in the locomotion of vertebrates. Physiol. Rev 69, 1199–.
    OpenUrlFREE Full Text
    1. Alexander, R. McN
    (1991). How dinosaurs ran. Scient. Am. 264, 130–136.
    1. Alexander, R. McN. and
    2. Jayes, A. S.
    (1980). Fourier analysis of forces exerted in walking and running. J. Biomech 13, 383–.
    OpenUrlCrossRefPubMedWeb of Science
    1. Blickhan, R.
    (1989). The spring-mass model for running and hopping. J. Biomech 22, 1217–.
    OpenUrlAbstract/FREE Full Text
    1. Cavagna, G. A.
    (1975). Force platforms as ergometers. J. Appl. Physiol 39, 174–.
    OpenUrl
    1. Cavagna, G. A.,
    2. Heglund, N. C. and
    3. Taylor, C. R.
    (1977). Mechanical work in terrestrial locomotion: two basic mechanisms for minimizing energy expenditure. Am. J. Physiol 233, 243–.
    OpenUrlPubMedWeb of Science
    1. Cavanagh, P. R. and
    2. Kram, R.
    (1989). Stride length in distance running: velocity, body dimensions and added mass effects. Med. Sci. Sports Exerc 21, 467–.
    OpenUrlPubMed
    1. Davis, B. L. and
    2. Cavanagh, P. R.
    (1993). Simulating reduced gravity: a review of biomechanical issues pertaining to human locomotion. Aviat. Space Env. Med 64, 557–.
    OpenUrlPubMed
    1. Davis, B. L.,
    2. Cavanagh, P. R. and
    3. Sommer, H. J.
    (1996). Ground reaction forces during locomotion in simulated microgravity. Aviat. Space Env. Med 67, 235–.
    OpenUrlAbstract
    1. Donelan, J. M. and
    2. Kram, R.
    (1997). The effect of reduced gravity on the kinematics of human walking: a test of the dynamic similarity hypothesis for locomotion. J. Exp. Biol 200, 3193–.
    OpenUrl
    1. Donelan, J. M.,
    2. Letson, B. G. and
    3. Kram, R.
    (1997). Effect of reduced gravity on running kinematics. Med. Sci. Sports Exerc 29, 81–.
    OpenUrlPubMedWeb of Science
    1. Farley, C. T. and
    2. Ferris, D. P.
    (1998). Biomechanics of walking and running: from center of mass movement to muscle action. Exerc. Sport Sci. Rev 26, 253–.
    OpenUrlAbstract
    1. Farley, C. T.,
    2. Glasheen, J. and
    3. McMahon, T. A.
    (1993). Running springs: speed and animal size. J. Exp. Biol 185, 71–.
    OpenUrlCrossRefPubMedWeb of Science
    1. Farley, C. T. and
    2. Gonzalez, O.
    (1996). Leg stiffness and stride frequency in human running. J. Biomech 29, 181–.
    OpenUrlAbstract/FREE Full Text
    1. Farley, C. T.,
    2. Houdijk, H. H.,
    3. Van Strien, C. and
    4. Louie, M.
    (1998). Mechanism of leg stiffness adjustment for hopping on surfaces of different stiffnesses. J. Appl. Physiol 85, 1044–.
    OpenUrlAbstract/FREE Full Text
    1. Farley, C. T. and
    2. McMahon, T. A.
    (1992). Energetics of walking and running: insights from simulated reduced-gravity experiments. J. Appl. Physiol 73, 2709–.
    OpenUrlPubMed
    1. Ferris, D. P.,
    2. Louie, M. and
    3. Farley, C. T.
    (1998). Running in the real world: adjusting leg stiffness for different surfaces. Proc. R. Soc. Lond. B 265, 989–.
    OpenUrlAbstract/FREE Full Text
    1. Full, R. J. and
    2. Tu, M. S.
    (1990). Mechanics of six-legged runners. J. Exp. Biol 148, 129–.
    OpenUrlAbstract/FREE Full Text
    1. Griffin, T. M.,
    2. Tolani, N. A. and
    3. Kram, R.
    (1999). Walking in simulated reduced gravity: mechanical energy fluctuations and exchange. J. Appl. Physiol 86, 383–.
    OpenUrlAbstract/FREE Full Text
    1. He, J. P.,
    2. Kram, R. and
    3. McMahon, T. A.
    (1991). Mechanics of running under simulated low gravity. J. Appl. Physiol 71, 863–.
    OpenUrlAbstract/FREE Full Text
    1. Kram, R.,
    2. Domingo, A. and
    3. Ferris, D. P.
    (1997). Effect of reduced gravity on the preferred walk—run transition speed. J. Exp. Biol 200, 821–.
    OpenUrlAbstract/FREE Full Text
    1. Kram, R.,
    2. Griffin, T. M.,
    3. Donelan, J. M. and
    4. Chang, Y. H.
    (1998). A force-treadmill for measuring vertical and horizontal ground reaction forces. J. Appl. Physiol 85, 764–.
    OpenUrlAbstract/FREE Full Text
    1. Lee, C. R. and
    2. Farley, C. T.
    (1998). Determinants of the center of mass trajectory in human walking and running. J. Exp. Biol 201, 2935–.
    OpenUrlAbstract/FREE Full Text
    1. McMahon, T.
    (1973). Size and shape in biology. Science 179, 1201–.
    OpenUrlAbstract/FREE Full Text
    1. McMahon, T. A.
    (1975). Using body size to understand the structural design of animals: quadrupedal locomotion. J. Appl. Physiol 39, 619–.
    1. McMahon, T. A. and
    2. Cheng, G. C.
    (1990). The mechanics of running: how does stiffness couple with speed?. J. Biomech 23, 1–.
    OpenUrlAbstract/FREE Full Text
    1. McMahon, T. A.,
    2. Valiant, G. and
    3. Frederick, E. C.
    (1987). Groucho running. J. Appl. Physiol 62, 2326–.
    1. Minetti, A. E.,
    2. Saibene, F.,
    3. Ardigo, L. P.,
    4. Atchou, G.,
    5. Schena, F. and
    6. Ferretti, G.
    (1994). Pygmy locomotion. Eur. J. Appl. Physiol 68, 285–.
    OpenUrlPubMed
    1. Newman, D. J.,
    2. Alexander, H. L. and
    3. Webbon, B. W.
    (1994). Energetics and mechanics for partial gravity locomotion. Aviat. Space Env. Med 65, 815–.
    OpenUrlCrossRefPubMedWeb of Science
    1. van Ingen Schenau, G. J. and
    2. Cavanagh, P. R.
    (1990). Power equations in endurance sports. J. Biomech 23, 865–.
    OpenUrlCrossRefPubMedWeb of Science
    1. Wagenaar, R. C. and
    2. Beek, W. J.
    (1992). Hemiplegic gait: a kinematic analysis using walking speed as a basis. J. Biomech 25, 1007–.
    OpenUrlPubMedWeb of Science
    1. Williams, K. R.
    (1985). The relationship between mechanical and physiological energy estimates. Med. Sci. Sports Exerc 17, 317–.
Back to top

 Download PDF

Email
Journal Articles
Exploring dynamic similarity in human running using simulated reduced gravity
J.M. Donelan, R. Kram
Journal of Experimental Biology 2000 203: 2405-2415;
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

Welcome to JEB’s new Editor Monica Daley

We are pleased to welcome Monica Daley to JEB’s Editorial team. Monica has had a long association with JEB before taking up her new role, overseeing peer review of neuromuscular physiology, terrestrial biomechanics and integrative physiology of locomotion.

In the field with Robyn Hetem

Continuing our fieldwork series, Robyn Hetem reflects on working with species ranging from aardvark to zebra, and the impact COVID-19 has had on fieldwork.

Read & Publish participation continues to grow

“It is particularly encouraging for early career researchers, as it allows them to display their research globally without the need to find costs to cover the open access option.”

Professor Fernando Montealegre-Z (University of Lincoln) shares his experience of publishing Open Access as part of our growing Read & Publish initiative. We now have over 150 institutions in 15 countries and four library consortia taking part – find out more and view our full list of participating institutions.

Nocturnal reef residents have deep-sea-like eyes

Fanny de Busserolles and colleagues from The University of Queensland have discovered that the eyes of nocturnal reef fish have multibank retinas, layers of photoreceptors, similar to the eyes of deep-sea fish that live in dim light conditions.

Mechanisms underlying gut microbiota–host interactions in insects

In their Review, Konstantin Schmidt and Philipp Engel summarise recent findings about the mechanisms involved in gut colonisation and the provisioning of beneficial effects in gut microbiota–insect symbiosis.