Functional impact of sarcopenia in respiratory muscles

Abstract

The risk for respiratory complications and infections is substantially increased in old age, which may be due, in part, to sarcopenia (aging-related weakness and atrophy) of the diaphragm muscle (DIAm), reducing its force generating capacity and impairing the ability to perform expulsive non-ventilatory motor behaviors critical for airway clearance. The aging-related reduction in DIAm force generating capacity is due to selective atrophy of higher force generating type IIx and/or IIb muscle fibers, whereas lower force generating type I and IIa muscle fiber sizes are preserved. Fiber type specific DIAm atrophy is also seen following unilateral phrenic nerve denervation and in other neurodegenerative disorders. Accordingly, the effect of aging on DIAm function resembles that of neurodegeneration and suggests possible common mechanisms, such as the involvement of several neurotrophic factors in mediating DIAm sarcopenia. This review will focus on changes in two neurotrophic signaling pathways that represent potential mechanisms underlying the aging-related fiber type specific DIAm atrophy.

Diaphragm abnormalities in heart failure and aging: mechanisms and integration of cardiovascular and respiratory pathophysiology

“…Beyond being active during breathing, inspiratory muscles are recruited near-maximally during expulsive behaviors, e.g., sneezing or coughing [1–3]. Therefore, loss of inspiratory muscle function can compromise gas exchange and the health of the pulmonary system.…”

“…The diaphragm is the primary inspiratory muscle and, in CHF, abnormalities of the diaphragm occur earlier or to a greater extent than in limb muscles [9–13]. Similarly, aging causes diaphragm abnormalities [14–16,1]. The combined effects of aging and CHF are unclear because experimental models typically address each condition separately.…”

The Influence of Changed Life Environment on Swallowing and Respiration in Healthy Elderly: A Comparison of Disaster Victim and Non-Victim Elderly Individuals

“…The Fukushima group (as a whole, and the subgroups representing four regions) showed a significant reduction in respiratory function with the party horn test as compared to the Nagasaki group. This may imply that elderly individuals living in Fukushima have lost skeletal muscle strength, including that of the respiratory muscles [7], due to activity-related sarcopenia [8]. Moreover, the Fukushima group showed a significant reduction in swallowing function with the RSST, with the value in the group A (Fukushima) significantly lower than that in the group E (Nagasaki).…”

A musculatura ventilatória em indivíduos sadios: influência do gênero, da faixa etária, da posição corpórea e do exercício - um estudo transversal

“…Nos seres humanos, a redução da massa e força muscular esquelética começa a ocorrer por volta dos 30 anos de idade (60). A progressão desta perda varia de meio a um por cento ao ano e o maior declínio acontece após os 65 anos de idade (61).…”

“…Indivíduos idosos podem cursar com sarcopenia diafragmática relacionada ao envelhecimento, atrofia muscular e consequente redução da capacidade de geração de força (60).…”