Strength and Power of Knee Extensor Muscles

In the studies of human neuromuscular function, the function of leg muscles has been most often measured, particularly the function of the knee extensors. Therefore, this review will be focused on knee extensors, methods for assessment of its function, the interdependence of strength and power, relations that describe these two abilities and the infl uence of various factors on their production (resistance training, stretching, movement tasks, age, etc.). Given that it consists of four separate muscles, the variability of their anatomical characteristics affects their participation in strength and power production, depending on the type of movement and motion that is performed. Since KE is active in a variety of activities it must be able to generate great strength in a large and diverse range of muscle lengths and high shortening velocities, in respect to different patterns of strength production, and thus different generation capacities within the muscle (Blazevich et al., 2006). It has been speculated that KE exerts its Pmax at workloads close to subject’s own body weight or lower (Rahmani et al., 2001), which is very close to the maximum dynamic output hypothesis (MDI) of Jaric and Markovic (2009). Changes under the infl uence of resistance training or biological age are variously manifested in muscle’s morphological, physiological and neural characteristics, and thus in strength and power. Understanding the issues related to strength and power as abilities of great importance for daily activities, is also important for sports and rehabilitation. Performances improvement in sports in which leg muscles strength and power are crucial, as well as recovery after the injuries, are largely dependent on the research results regarding KE function. Also, the appropriate strength balance between knee fl exors and extensors is important for the knee joint stability, so that the presence of imbalance between these two muscle groups might be a risk factor for the occurrence of injuries. Кеy words: MUSCLE STRUCTURE / MUSCLE ARCHITECTURE / NEUROMUSCULAR FUNCTION ASSESSMENT / STRENGTH TRAINING Correspondence to: Olivera Knezevic, University of Belgrade, Faculty of Sport and Physical Education Blagoja Parovića 156, 11 000 Belgrade, Serbia, e-mail: [email protected] INTRODUCTION The motor abilities such as strength, power and their manifestations trough functional tasks have an important role in daily activities, sports and related areas sports medicine, physical education, physical therapy, rehabilitation, ergonomics (Wilson, 1996; Kadija, Knezevic, Milovanovic, Bumbasirevic, & Mirkov, 2010; Knezevic, & Mirkov, 2010). The research of neuromuscular function based on evaluation of force (strength) and power parameters has been the subject of numerous research studies. Nevertheless, there are a number of terminological prob-