ABSTRACT

Kinetic and kinematic measurements provide either direct or indirect insight into the values of the resulting forces and the moments of force acting between the body and its surroundings, i.e., at the imaginary connections of particular body segments. In addition, a subgroup of kinetic measurement methods provides pressure distributions at the supporting surfaces. A more-detailed and fundamental physical study of the behavior of various biological tissues under the influence of mechanical loading caused by movement, or by static loading, is outside the scope of this book. The reader may refer to the literature.2,24,180,181 Furthermore, by measuring kinematic quantities only and measuring and/or estimating kinetic (dynamic) quantities, the energy balance of movements measured may be estimated.12,182 –185 While this falls outside the scope of this book, it should be mentioned that in the biomechanics and physiology of activity, the “gold standard” and criterion for energy expenditure of an organism are procedures with the Douglas bag, a treadmill, and pulse and oxygen consumption measurements. These procedures should therefore, when possible, be applied simultaneously with the biomechanical measurements of the locomotions concerned.1,186

The next step toward profound locomotion analysis is based on a more-detailed modeling of the anatomical structure of the locomotor apparatus and, specifically, efforts to estimate contributions of particular muscular groups to the total resultant forces and moments in the locomotor apparatus. Attention is directed to the skeletal muscle viewed as a force actuator and a neuromechanical converter, characterized at the macroscopic level by the features of elasticity, viscosity, and mass (Section 2.3). Because muscular force is not practically susceptible to measurement in vivo noninvasively, electrical processes in muscles are accessible for measurement by means of the electromyography method. This method concerns the measurement (detection and amplification) and registration of changes in the motor unit’s electrical action potentials accompanying the process of muscular contraction (Section 2.3). Bioelectric muscle activity may provide insight into bioinformation and biocommunication (muscular coordination, speed of muscle activation) and the bioenergetic aspects of muscle function (energy expenditure necessary for muscular tissue metabolism, local muscle fatigue), both of which are of interest to the study of locomotion, healthy and pathological.