The performance of a skeletal muscle during movement is determined by the interaction of its intrinsic properties with the mechanical properties of the system to which it is linked. These interactions are complex and predictive equations are limited in some respects by the lack of empirical data on the performance of muscle under loading conditions that replicate those found during movement. Muscles serve three major mechanical functions during movement: producing force, producing work, and providing stability. These different functions are linked to differences in the length trajectory (sequence of length change) in relation to the motor activity of the muscles. Although we know that all three of these functions are performed by humans in walking and running, we know little of the conditions under which individual muscles operate while performing each function. Further we have no empirical data on the quantitative importance of each function to the cost of locomotion.
The specific aims of this project are to: 1) Examine the in vivo contractile parameters (operational lengths, length trajectories, and amounts of series elasticity) for muscles that are active only while performing positive work in running and jumping; 2) Examine the prediction that during running and jumping actively lengthening muscles function to help stabilize the movement; 3) Quantify the relative energetic importance of the different mechanical functions served by muscles during running; 4) Measure the efficiency of fast and slow muscles under conditions of varying power output; 5) Quantify the influence of velocity dependent activation and deactivation on mechanical function of fast and slow muscles. The mechanical function of muscles used in running and jumping will be assessed in vivo using sonomicrometry and electromyography. Blood flow measurements using fluorescently labeled microspheres will be used in conjunction with other measures to estimate the relative contribution of the different limb muscles to the energy cost of running. In vitro work with the muscles used in jumping and running and computer modeling will examine the optimum conditions for accelerating inertial loads. Mouse muscles will be used to examine the influence of length trajectory and cycle frequency on mechanical performance and efficiency. This project is predicated on the assumption that examining how muscles are used in animals during movement allows us to better predict the design parameters important in human movement and will improve our understanding of both normal and dysfunctional human movement. Such studies will eventually assist in designing rehabilitative strategies that require an understanding of the diverse roles of muscles during movement.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
5R01AR047337-04
Application #
6727467
Study Section
Geriatrics and Rehabilitation Medicine (GRM)
Program Officer
Nuckolls, Glen H
Project Start
2001-02-01
Project End
2006-01-31
Budget Start
2004-02-01
Budget End
2005-01-31
Support Year
4
Fiscal Year
2004
Total Cost
$301,150
Indirect Cost
Name
Northeastern University
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
001423631
City
Boston
State
MA
Country
United States
Zip Code
02115
Carr, Jennifer A; Ellerby, David J; Rubenson, Jonas et al. (2011) Mechanisms producing coordinated function across the breadth of a large biarticular thigh muscle. J Exp Biol 214:3396-404
Carr, Jennifer A; Ellerby, David J; Marsh, Richard L (2011) Function of a large biarticular hip and knee extensor during walking and running in guinea fowl (Numida meleagris). J Exp Biol 214:3405-13
Watson, Rebecca R; Rubenson, Jonas; Coder, Lisa et al. (2011) Gait-specific energetics contributes to economical walking and running in emus and ostriches. Proc Biol Sci 278:2040-6
Carr, Jennifer A; Ellerby, David J; Marsh, Richard L (2011) Differential segmental strain during active lengthening in a large biarticular thigh muscle during running. J Exp Biol 214:3386-95
Umberger, Brian R; Rubenson, Jonas (2011) Understanding muscle energetics in locomotion: new modeling and experimental approaches. Exerc Sport Sci Rev 39:59-67
Ellerby, David J; Marsh, Richard L (2010) The mechanical function of linked muscles in the guinea fowl hind limb. J Exp Biol 213:2201-8
Rubenson, Jonas; Marsh, Richard L (2009) Mechanical efficiency of limb swing during walking and running in guinea fowl (Numida meleagris). J Appl Physiol (1985) 106:1618-30
Marsh, Richard L; Ellerby, David J; Henry, Havalee T et al. (2006) The energetic costs of trunk and distal-limb loading during walking and running in guinea fowl Numida meleagris: I. Organismal metabolism and biomechanics. J Exp Biol 209:2050-63
Ellerby, David J; Marsh, Richard L (2006) The energetic costs of trunk and distal-limb loading during walking and running in guinea fowl Numida meleagris: II. Muscle energy use as indicated by blood flow. J Exp Biol 209:2064-75
Rubenson, Jonas; Henry, Havalee T; Dimoulas, Peter M et al. (2006) The cost of running uphill: linking organismal and muscle energy use in guinea fowl (Numida meleagris). J Exp Biol 209:2395-408

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