The effects of aging on biceps brachii muscle fibers: a morphometrical study from biopsies and autopsies

Abstract

-Objectives: In order to study the morphology and size of muscle fibers, cross sections of biceps brachii samples from autopsies, up to 9 hours after death, and biopsies of 72 subjects were compared. The subjects aged 13 to 84 years in both sexes. Methods: The samples obtained from autopsies (n=47) were from subjects with sudden death, or who died after acute disease without evidence of neuromuscular involvement. The biopsies (n=25) were from patients with symptoms suggestive of inflammatory or metabolic myopathy, not confirmed morphologically. The lesser diameter of muscle fibers was measured using the ATPase reaction. Results: Morphological analysis showed that aging changes were present from the sixth decade in autopsies, and consisted of atrophy and/or type-grouping. The statistical models adjusted for females in both autopsies and biopsies were linear straight with no variation in fiber size with increasing age. The models adjusted for males in both groups were quadratic, indicating that age influenced the size of different type fibers. In males type 2 were larger than type 1 fibers, and than fibers in females. Conclusions: These values might be useful as controls, helping interpretation of changes in fiber size in samples obtained from biopsies and autopsies.KEY WORDS: biceps brachii, morphometry, aging, autopsy, muscle biopsy.Efeitos do envelhecimento sobre as fibras do músculo biceps braquial: estudo morfométrico em biópsias e autópsias RESUMO -Objetivos: Para estudar a morfologia e o tamanho das fibras musculares, foram comparadas cortes transversos do bíceps braquial autopsiados, até 9 horas após o óbito, com biopsias musculares, em 72 indivíduos de ambos os sexos e idades entre 13 e 84 anos. Método: As amostras das autópsias (n=47) foram obtidas de indivíduos que morreram subitamente, ou após uma doença aguda sem evidência de comprometimento neuromuscular. As biópsias (n=25) foram obtidas de pacientes com sintomas sugestivos de miopatias inflamatória ou metabólica, não confirmadas morfologicamente. O diâmetro menor das fibras foi obtido usando a reação de ATPase. Resultados: A análise morfológica mostrou que as mudanças induzidas pelo envelhecimento estiveram presentes a partir da sexta década para autópsias e consistiu de atrofia e grupamento de tipo. O modelo estatístico ajustado para mulheres, para autópsias e biópsias, foi linear e não indicou variação do tamanho das fibras com o aumento da idade. O modelo ajustado para homens, para ambos os casos, foi quadrático, indicando que a idade influenciou o tamanho dos diferentes tipos de fibras. Para homens, as fibras tipo 2 apresentaram-se maiores que as de tipo 1, e maiores que as das mulheres. Conclusão: Os valores encontrados podem ser úteis como controles, auxiliando na interpretação de modificações no tamanho das fibras para amostras provindas de biópsia e autópsia.

Effects of chronic heart disease on skeletal muscle fiber size

“…The mean lesser diameter obtained for all subjects of both sexes was within the normal values established by Brooke and Engel (15), 40-80 µm for males and 30-70 µm for females, using 103 samples, and by MattielloSverzut et al (16), 34-71 and 34-65 µm for type 1 fibers, and 36-79 and 32-59 µm for type 2 fibers, in males and females, respectively, using 72 samples. In males with or without chronic cardiomyopathy, type 2 fibers were larger than type 1 fibers, while in females, type 1 fibers were larger than type 2 fibers, as observed by Brooke and Engel (15) in normal muscles.…”

The Interaction of Aging and 10 Years of Racing on Ultraendurance Running Performance

“…These changes manifest as a reduced functional capacity during activities of daily living and exercise. More specifically, the agerelated alterations to physical capacity can be, at least partially, attributed to the observed changes in skeletal-muscle strength (Lynch et al, 1999), morphology (Mattiello-Sverzut, Chimelli, de Assis Moura, Teixeira, & de Oliveira, 2003), metabolism (Coggan et al, 1992a;Russ & Kent-Braun, 2004), and changes in the neuromuscular system (Laidlaw, Bilodeau, & Enoka, 2000;Thompson, 1994).…”

Synergistic effect of bodyweight resistance exercise and protein supplementation on skeletal muscle in sarcopenic or dynapenic older adults

“…It is well established that not only muscle quantity, but also muscle quality is important in older populations. The qualitative changes in skeletal muscle in sarcopenia and dynapenia can be caused by increases in fat infiltration within the skeletal muscle and decreases in the number of fast twitch fibers . Furthermore, lower muscle quality is associated with poor physical performance and leads to mobility limitations in the future .…”

“…The qualitative changes in skeletal muscle in sarcopenia and dynapenia can be caused by increases in fat infiltration within the skeletal muscle 6,7 and decreases in the number of fast twitch fibers. 8,9 Furthermore, lower muscle quality is associated with poor physical performance and leads to mobility limitations in the future. [10][11][12][13] Importantly, magnetic resonance imaging, computed tomography and ultrasonography can be used to estimate muscle quality, such as intramuscular adipose tissue (IMAT).…”