Manipulations of leg mass and moment of inertia: effects on energy cost of walking.

PURPOSE To investigate effects that independent alterations in limb mass and moment of inertia about a transverse axis through the hip have on metabolic and mechanical power of walking and peak electromyography (EMG) amplitude. It was hypothesized that increases in metabolic cost would parallel increases in mechanical power, and that EMG amplitude would increase with greater limb mass or limb moment of inertia. METHODS Metabolic and mechanical power and lower-extremity EMG were measured on 14 healthy adults walking at 1.5 m.s. Four leg-loading conditions were employed: 1) no load (NL) on the legs; 2) a baseline load (BSLN) condition, with a mean of 2.0 kg per leg distributed on the proximal and distal shank; 3) a load condition with a mean of 2.0 kg per leg distributed on the proximal and distal shank, such that lower-extremity moment of inertia was increased 5% about the hip (MOI5) from the BSLN, but having the same lower-extremity mass as BSLN; and 4) a load condition with a mean of 2.8 kg per leg, concentrated proximally on the shank to increase total lower-extremity mass by 5% (Mass5) from BSLN, but having the same moment of inertia as BSLN. Total subject mass was constant between conditions, as unused leg loads were carried in a waist belt. RESULTS Changes in mechanical power paralleled changes in metabolic cost as hypothesized. Energy cost increased significantly (4.2%) from NL to BSLN, and from BSLN to MOI5 and Mass5 (3.4 and 4.0%, respectively). EMG did not effectively explain changes in metabolic cost. CONCLUSION Independent alterations in limb mass and moment of inertia about the hip joint influence energy cost similarly.

[1]  T P Andriacchi,et al.  Walking speed as a basis for normal and abnormal gait measurements. , 1977, Journal of biomechanics.

[2]  R W Norman,et al.  Mechanical energy analyses of the human during local carriage on a treadmill. , 1981, Ergonomics.

[3]  S R Simon,et al.  Analysis and synthesis of human swing leg motion during gait and its clinical applications. , 1981, Journal of biomechanics.

[4]  Morrison Jb,et al.  Kinematic symmetry of the lower limbs. , 1984 .

[5]  J. F. Yang,et al.  Electromyographic amplitude normalization methods: improving their sensitivity as diagnostic tools in gait analysis. , 1984, Archives of physical medicine and rehabilitation.

[6]  P. E. Martin Mechanical and physiological responses to lower extremity loading during running. , 1985, Medicine and science in sports and exercise.

[7]  J. Hamill,et al.  The force-driven harmonic oscillator as a model for human locomotion , 1990 .

[8]  H B Skinner,et al.  Ankle weighting effect on gait in able-bodied adults. , 1990, Archives of physical medicine and rehabilitation.

[9]  H B Skinner,et al.  Ankle weight effect on gait: orthotic implications. , 1993, Orthopedics.

[10]  M. Nash,et al.  Energy expenditure of trans-tibial amputees during ambulation at self-selected pace , 1994, Prosthetics and orthotics international.

[11]  E. Ayyappa,et al.  Influence of prosthetic foot design on sound limb loading in adults with unilateral below-knee amputations. , 1994, Archives of physical medicine and rehabilitation.

[12]  J. Czerniecki,et al.  EFFECT OF ALTERATIONS IN PROSTHETIC SHANK MASS ON THE METABOLIC COSTS OF AMBULATION IN ABOVE-KNEE AMPUTEES , 1994, American journal of physical medicine & rehabilitation.

[13]  C D Mote,et al.  The prediction of metabolic energy expenditure during gait from mechanical energy of the limb: a preliminary study. , 1995, Journal of rehabilitation research and development.

[14]  P. Leva Adjustments to Zatsiorsky-Seluyanov's segment inertia parameters. , 1996 .

[15]  J. Lehmann,et al.  Mass and mass distribution of below-knee prostheses: effect on gait efficacy and self-selected walking speed. , 1998, Archives of physical medicine and rehabilitation.

[16]  R. Waters,et al.  The energy expenditure of normal and pathologic gait. , 1999, Gait & posture.

[17]  J B Bussmann,et al.  Effects of prosthetic mass and mass distribution on kinematics and energetics of prosthetic gait: a systematic review. , 1999, Archives of physical medicine and rehabilitation.

[18]  Gail Frost,et al.  mechanical and Metabolic Work of Persons with Lower-extremity Amputations Walking with Titanium and Stainless Steel Prostheses : a Preliminary Study , 1999 .

[19]  P. E. Martin,et al.  Walking symmetry and energy cost in persons with unilateral transtibial amputations: matching prosthetic and intact limb inertial properties. , 2000, Archives of physical medicine and rehabilitation.

[20]  J. Bussmann,et al.  Comparing predictive validity of four ballistic swing phase models of human walking. , 2001, Journal of biomechanics.