An exploration of the association between frailty and muscle fatigue

Abstract

Frailty is increasingly recognized as a geriatric syndrome that shares common biomedical determinants with rapid muscle fatigue: aging, disease, inflammation, physical inactivity, malnutrition, hormone deficiencies, subjective fatigue, and changes in neuromuscular function and structure. In addition, there is an established relationship between muscle fatigue and core elements of the cycle of frailty as proposed by Fried and colleagues (sarcopenia, neuroendocrine dysregulation and immunologic dysfunction, muscle weakness, subjective fatigue, reduced physical activity, low gait speed, and weight loss). These relationships suggest that frailty and muscle fatigue are closely related and that low tolerance for muscular work may be an indicator of frailty phenotype.

Fatigue in older adults: an early indicator of the aging process?

“…Fatigue is a general reaction to many biological processes after intensive and/or long-lasting work, because metabolic demands cannot be met. This may occur outside the central nervous system, e.g., in muscles, after heavy and intensive stimulation, as feedback from joints, muscles and tendons (23). Muscle fatigue has been defined as a fall in the maximum force-generating capacity of the muscle and its failure to maintain the required force, resulting from muscle activity, but reversible by rest.…”

“…Muscle fatigue has been defined as a fall in the maximum force-generating capacity of the muscle and its failure to maintain the required force, resulting from muscle activity, but reversible by rest. Muscle fatigue is considered to be both a "negative" consequence of physical activity and a "positive" safety mechanism, to prevent injury or death during exercise (23). Centrally conditioned fatigue is more complex, and entails both chemical and hormonal factors in nerve cells and their synapses, e.g., as changes in neurotransmitter levels in various brain structures (24), but also psychological factors such as endurance, motivation (25,26), mood, and expectation of task difficulty (23,27).…”

“…However, other types of age-related decline may also play a role, e.g., age-related decline in the nervous and sensory system (95), immunological system (150-152) and anemia (23). Additional explanations may include pain, sleep, medication and health behavior.…”

Launching a new initiative

“…These authors acknowledged that frail older adults respond remarkably well to exercise but emphasized that more research was required to support exercise as a means to reverse frailty. A number of factors inclusive of but not limited to age, disease, inactivity, malnutrition, neuromuscular remodelling, and hormonal deficiency are synonymous with both frailty and muscle fatigue, leading to lower tolerance for muscular work (Theou et al 2008). Theou et al (2011) proposed that performance-based measures be considered effective screening tools for frailty.…”

Síndrome de fragilidade aumenta a suscetibilidade à ventilação mecânica?

“…ventilação mecânica 6,7,9 e, dessa forma, tais pacientes ficam mais vulneráveis a complicações da própria ventilação mecânica, como aspiração e pneumonia nosocomial. 9 Contextualmente, desnutrição, sarcopenia e delírio são marcadores da síndrome de fragilidade 10 que, associados à idade avançada, são fortes preditores de insuficiência respirató-ria. 5 Interação desses fatores pode culminar com a vulnerabilidade fisiológica resultante da prejudicada reserva homeostática e subsequente redução da capacidade do organismo para suportar o estresse.…”