An Age-Related Morphometric Profile of Skeletal Muscle in Healthy Untrained Women

Abstract

There is a paucity of data on muscle biopsies in females of mixed ages in terms of age-related changes. Cross sections of autopsy material including the quadriceps femoris and biceps brachii muscles were obtained from 23 healthy women, aged 24–82 years, who had suffered sudden death. We calculated the percentage of the number, and the mean diameter, of type I and type II muscle fibers within the fascicles as well as in their peripheral parts. The number of type II fibers were shown to reduce significantly with age (p < 0.005), especially in the fascicle periphery, but the percentage of type 1 fibers did not alter significantly. It was noted that type II fibers diminished in size with age, indicating a relationship between fiber size and age. This result became more apparent in the fascicle periphery (p < 0.05). In women, type II muscle fibers were seen to reduce in size and number with advancing age. We postulate that regular physical activity can increase the size of type II muscle fibers, thus helping to both prevent and treat age-related muscle loss.

Age-related degeneration of the lumbar paravertebral muscles: Systematic review and three-level meta-regression

“…Indeed, given the predominance of type I fibres in the lumbar paravertebral muscles (Kimura, 2002;Mannion et al, 1997;Ng et al, 1998;Parkkola et al, 1993a;Sirca and Kostevc, 1985) and that type I fibres tend to accumulate fat deposits with age (Choi et al, 2016;Gueugneau et al, 2015) whilst fast-twitch fibres typically exhibit greater atrophy with age (Gueugneau et al, 2015;Lexell et al, 1988;Novotny et al, 2015), it is unsurprising that fat infiltration was the more apparent degenerative feature in the lumbar musculature. Although the findings in this review can be explained by established mechanisms that contribute to the development and morphological expressions of age-related sarcopenia (Bougea et al, 2016;Doherty, 2003;Klitgaard et al, 1990;Larsson et al, 1979;Vettor et al, 2009;von Haehling et al, 2010), confidence in the findings is diminished somewhat by the substantial variance between studies. However, disparate methods and population characteristics amongst studies included in this review were able to explain a large proportion of variance and shed light on which factors play a pivotal role in moderating the agerelated changes in lumbar paravertebral muscle morphology.…”

Role of Menopausal Transition and Physical Activity in Loss of Lean and Muscle Mass: A Follow-Up Study in Middle-Aged Finnish Women

“…Aging has been shown to decrease muscle fiber area and there is evidence, albeit conflicting, of a shift in the muscle fiber type ratio towards a slower or more hybrid phenotype [38][39][40]. Most studies have reported that aging causes more visible changes in the size of type II fibers, while the size of slow type I fibers stays relatively unchanged in both sexes [41][42][43][44]. The role of aging in muscle tissue myosin expression has been previously studied in women in one cross-sectional study that compared 30-and 68-year old women, and the results also suggested a shift toward a slower phenotype in the older group [40].…”

“…Therefore, we cannot totally exclude the possibility that small sample size may have affected our results. When interpreting the results, it is also important to note that both muscle fiber CSA and fiber/myosin isoform proportions are known to be affected by the site of biopsy [41,44], and this might also have affected our results. Although we were obviously not able to obtain the follow-up biopsy from the exact same location as at baseline, an effort was made to take it from the closest proximity (~1 cm apart).…”

Comprehensive morphometric assessment of deltoid muscle development in children: A cross-sectional study

“…Other authors 15 point to an equivalent number of type 1 and 2 fibres in males. The relative number of each fibre type is highly dependent on exercise, age 16 and gender. 17 …”