Force, velocity and energy dynamics of nine load-moving muscles

• Published in: Medical engineering & physics Vol. 19; no. 1; pp. 37 - 49
• Main Authors: Baratta, R.V., Solomonow, M., Best, R., D'Ambrosia, R.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 1997; Elsevier Science
• Subjects: Animals; Biological and medical sciences; Biomechanical Phenomena; Biomedical Engineering - instrumentation; Biophysics - instrumentation; Cats; contraction; efficiency; Electric Stimulation; energy; Energy Metabolism; Fundamental and applied biological sciences. Psychology; Gravitation; Hindlimb; Muscle; Muscle Contraction - physiology; Muscle, Skeletal - physiology; muscle-force; Space life sciences; Stress, Mechanical; Striated muscle. Tendons; Vertebrates: osteoarticular system, musculoskeletal system; contraction; muscle-force; efficiency; Muscle; energy; Potential energy; Gravitational force; Fissipedia; Carnivora; Hindlimb; Force measurement; Dynamic characteristic; Experimental study; Muscle contraction; Loading test; Vertebrata; Mammalia; Animal; Cat; Kinetic energy
• ISSN: 1350-4533; 1873-4030
• DOI: 10.1016/S1350-4533(96)00036-7

Nine architecturally different muscles of the cat's hindlimb were investigated with respect to the kinetic energy, the potential energy, and the force variations associated with shortening contractions against gravitational loads. Insight about the energy dynamics of contractile muscle can provide a unifying concept for models of muscle performance capability. In this study, it was found that as contractions shortened from passive equilibrium against a constant mass load, acceleration and deceleration phases appeared. These phases were associated with muscular force variations of up to 25% of the mass weight in fast twitch muscles at low loads. In contrast, slow twitch muscles were associated with less than 10% force variations when shortening against a gravitational load. It also was found that optimal loads exist which maximize each muscle's ability to impart kinetic and potential energy; these optimal loads tend to be in the mid-force range for highly pennate muscle and in the low-force range for fusiform muscles. It was concluded that the kinetic energy provided by each muscle is a small percentage of that calculated from its length-force relationship, especially at low loads. This study confirms that the efficiency of kinetic energy conversion is very low at low loads (gradually improving as the loads increase) and thereby substantiates early experiments with heat and metabolic energy.