This chapter summarizes studies that examine remodelling of extracellular matrix (ECM) and role of regulatory factors of ECM during unloading and reloading. Hypokinesia has a catabolic effect on both the contractile apparatus and ECM of the skeletal muscle, causing the formation of muscle atrophy, the decrease of the synthesis of contractile proteins and disturbance of the collagen metabolism. The metabolism of fibrillar and non-fibrillar collagens in ECM plays a crucial role in exercise and sport, influencing the strength development through transmission of contractile force in skeletal muscle. The impairment of motor activity and muscle strength is accompanied by the muscle atrophy. The muscle atrophy caused by inactivity and recovery from atrophy demonstrates the plasticity of muscle. Muscle mass and volume increase in a relatively short time, but the recovery of strength takes much longer and is related with the regeneration of the muscle structures. The recovery period of the contractile apparatus and ECM structures is different in slow-and fast-twitch skeletal muscle.
Part of the book: Composition and Function of the Extracellular Matrix in the Human Body
Fostering childhood physical activity and fitness levels could have important implications for public health, given growing concerns about high obesity rates, the amount of time spent being sedentary and not getting enough physical activity already at early childhood. World Health Organization states that from 1975 to 2016, the prevalence of children and adolescents with overweight or obesity increased more than four-fold from 4% to 18% globally. Obesity prevention is critical in controlling obesity-related noncommunicable diseases, psychological, and social problems, as well as inferior academic achievement mediated by others attitude and diminished executive cognitive function. A decline of physical activity from early childhood into middle childhood and further to adolescence has been reported. Accompanying health risks from low activity and high sedentariness are comparable to those arising from obesity, and the impact extends into adulthood. Wide range of physical, mental, and cognitive health benefits related to high physical fitness levels in children have been reported. This chapter aims to summarize current evidence clarifying whether higher physical activity is associated with higher physical fitness, and whether higher physical fitness predicts healthier body composition and better cognitive functions in children.
Part of the book: Updates on Physical Fitness in Children