Muscle Fatigue during High-Intensity Exercise in Children

Abstract

Children are able to resist fatigue better than adults during one or several repeated high-intensity exercise bouts. This finding has been reported by measuring mechanical force or power output profiles during sustained isometric maximal contractions or repeated bouts of high-intensity dynamic exercises. The ability of children to better maintain performance during repeated high-intensity exercise bouts could be related to their lower level of fatigue during exercise and/or faster recovery following exercise. This may be explained by muscle characteristics of children, which are quantitatively and qualitatively different to those of adults. Children have less muscle mass than adults and hence, generate lower absolute power during high-intensity exercise. Some researchers also showed that children were equipped better for oxidative than glycolytic pathways during exercise, which would lead to a lower accumulation of muscle by-products. Furthermore, some reports indicated that the lower ability of children to activate their type II muscle fibres would also explain their greater resistance to fatigue during sustained maximal contractions. The lower accumulation of muscle by-products observed in children may be suggestive of a reduced metabolic signal, which induces lower ratings of perceived exertion. Factors such as faster phosphocreatine resynthesis, greater oxidative capacity, better acid-base regulation, faster readjustment of initial cardiorespiratory parameters and higher removal of metabolic by-products in children could also explain their faster recovery following high-intensity exercise.From a clinical point of view, muscle fatigue profiles are different between healthy children and children with muscle and metabolic diseases. Studies of dystrophic muscles in children indicated contradictory findings of changes in contractile properties and the muscle fatigability. Some have found that the muscle of boys with Duchenne muscular dystrophy (DMD) fatigued less than that of healthy boys, but others have reported that the fatigue in DMD and in normal muscle was the same. Children with glycogenosis type V and VII and dermatomyositis, and obese children tolerate exercise weakly and show an early fatigue. Studies that have investigated the fatigability in children with cerebral palsy have indicated that the femoris quadriceps was less fatigable than that of a control group but the fatigability of the triceps surae was the same between the two groups. Further studies are required to elucidate the mechanisms explaining the origins of muscle fatigue in healthy and diseased children. The use of non-invasive measurement tools such as magnetic resonance imaging and magnetic resonance spectroscopy in paediatric exercise science will give researchers more insight in the future.

Skeletal age and explosive strength in young volleyball players

“…However, because of their invasive nature, metabolic responses in children and adolescents according to maturational development are limited. However, based on the aforementioned studies, it is possible to hypothesize that lower hormonal circulation and amounts of type ibers II, may explain, in part, the diferences in explosive strength performance among maturational 24 . Body changes in height and body mass inherent to maturational process 5,10 have been proposed by some authors to explain diferences in performance and muscle strength according to anthropometric variables 6,11 .…”

Dietary acid load and renal function have varying effects on blood acid-base status and exercise performance across age and sex

“…Moreover, adolescents have higher oxidative capacity compared with adults at rest (Ratel et al 2006), which could enable a more efficient utilization of H + in tricarboxylic acid cycle. Growing adolescents also have higher needs for protein to ensure the growing and maturation of the tissues and the efficacy to use nitrogen is increased (Giovannini et al 2000).…”

Changes in Myofibrillar and Mitochondrial Compartments during Increased Activity: Dependance from Oxidative Capacity of Muscle

“…As children muscle mass is much less in comparison with adults, they generate lower absolute power during intensive muscle activity. Children's muscles are better equipped for oxidative than glycolytic pathways during increased functional activity and have lower capacity to activate type II (fast-twitch) fibers [10]. Oxidative capacity of skeletal muscle increases with aerobic type of muscle activity, and an age-associated decline in oxidative capacity is related to the reduction in fitness [11].…”