title: The mechanics and energetics of human walking and running: a joint level perspective.
abstract: Humans walk and run at a range of speeds. While steady locomotion at a given speed requires no net mechanical work, moving faster does demand both more positive and negative mechanical work per stride. Is this increased demand met by increasing power output at all lower limb joints or just some of them? Does running rely on different joints for power output than walking? How does this contribute to the metabolic cost of locomotion? This study examined the effects of walking and running speed on lower limb joint mechanics and metabolic cost of transport in humans. Kinematic and kinetic data for 10 participants were collected for a range of walking (0.75, 1.25, 1.75, 2.0 m s(-1)) and running (2.0, 2.25, 2.75, 3.25 m s(-1)) speeds. Net metabolic power was measured by indirect calorimetry. Within each gait, there was no difference in the proportion of power contributed by each joint (hip, knee, ankle) to total power across speeds. Changing from walking to running resulted in a significant (p = 0.02) shift in power production from the hip to the ankle which may explain the higher efficiency of running at speeds above 2.0 m s(-1) and shed light on a potential mechanism behind the walk-run transition.
authors: Department of Biomedical Engineering, North Carolina State University, 4130 EBIII, 911 Oval Drive, NC 27695-7115, USA. djfarris@ncsu.edu
authors: Dominic James
authors: DJ
authors: Farris
authors: Gregory S
authors: GS
authors: Sawicki
references: J Exp Biol. 2007 Sep;210(Pt 18):3255-65
references: 17766303
references: Arch Phys Med Rehabil. 2010 Jun;91(6):951-7
references: 20510989
references: J Exp Biol. 2005 Mar;208(Pt 5):799-808
references: 15755878
references: J Exp Biol. 1997 Feb;200(Pt 4):821-6
references: 9076966
references: Exerc Sport Sci Rev. 2000 Jul;28(3):138-43
references: 10916707
references: J Exp Biol. 2002 May;205(Pt 10):1485-94
references: 11976359
references: Gait Posture. 2008 Jul;28(1):135-43
references: 18158246
references: J Exp Biol. 1996 Apr;199(Pt 4):801-14
references: 8788087
references: J Physiol. 1977 Jun;268(2):467--81
references: 874922
references: J Exp Biol. 2008 Dec;211(Pt 23):3744-9
references: 19011215
references: J Exp Biol. 1982 Apr;97:23-40
references: 7086342
references: Acta Physiol Scand. 1994 Mar;150(3):315-23
references: 8010138
references: Comp Biochem Physiol A Mol Integr Physiol. 2002 Dec;133(4):1087-99
references: 12485693
references: Eur J Appl Physiol. 2003 Jan;88(4-5):297-316
references: 12527959
references: J Exp Biol. 1982 Apr;97:41-56
references: 7086349
references: J Biomech. 2010 Feb 10;43(3):412-9
references: 19879583
references: Hum Nutr Clin Nutr. 1987 Nov;41(6):463-71
references: 3429265
references: J Exp Biol. 1982 Apr;97:57-66
references: 7086351
references: J Biomech. 2007;40(1):157-64
references: 16364330
references: Gait Posture. 1998 Jan 1;7(1):77-95
references: 10200378
references: Gait Posture. 2006 Apr;23(3):383-90
references: 16029949
references: J Exp Biol. 2005 May;208(Pt 10):1963-70
references: 15879076
references: J Exp Biol. 2009 Mar;212(Pt 5):738-44
references: 19218526
references: J Biomech. 2009 Jun 19;42(9):1282-7
references: 19394023
references: Exerc Sport Sci Rev. 2009 Jul;37(3):130-8
references: 19550204
references: J Appl Physiol (1985). 2004 Dec;97(6):2266-74
references: 15258124
references: Gait Posture. 2007 Mar;25(3):380-4
references: 16784858
references: Nature. 1990 Jul 19;346(6281):265-7
references: 2374590