Muscle composition in relation to age and sex

Abstract

1. A method is described enabling the determination of fat, water, electrolytes, protein, DNA, RNA and total creatine in a single sample of human muscle obtained by the percutaneous needle-biopsy technique. The amino acid content can also be analysed in the same muscle sample. 2. Fifty healthy subjects were studied: 29 between 19 and 40 years of age, 11 between 41 and 60 years of age, and 10 between 61 and 85 years of age. The two groups aged less than 60 years showed only marginal differences in muscle composition, whereas the highest age group showed increases in muscle fat content in relation to tissue weight and decreases in alkali-soluble protein content in relation to both tissue weight and tissue DNA content. Also, potassium, magnesium, total creatine and RNA contents were decreased in this age group when related to tissue DNA content. When alkali-soluble protein was used as a reference base, only magnesium content was decreased. 3. A comparison was also made between female (n = 23) and male (n = 18) subjects in the age groups below 60 years. Differences observed included a higher fat content in female muscle, and an increase in total creatine content in relation to tissue weight. The alkalisoluble protein content was lower per muscle cell in the females when calculated on the basis of DNA content. 4. The results show that in the assessment of muscle constituents, age and sex must be taken into account.

Skeletal muscle low attenuation area and maximal fat oxidation rate during submaximal exercise in male obese individuals

“…of total muscle weight of male subjects. 18 From an equation described in the literature, 19 it can be estimated that muscle should contain more than 84% of water to reach the attenuations within the LAM range. This value is clearly out of the physiological range (ie 76 AE 1%).…”

Diagnostic Performance and Reliability of Ultrasonography for Fatty Degeneration of the Rotator Cuff Muscles

“…It is a well known phenomenon that aging muscles accumulate fat [24][25][26] , and it is not uncommon to see fatty streaks in the deltoid and trapezius muscles in the MRIs of elderly patients. This is a possible source of the discrepancy between ultrasonography and MRI in distinguishing a grade-1 muscle from a grade-0 muscle.…”

NMR imaging estimates of muscle volume and intramuscular fat infiltration in the thigh: variations with muscle, gender, and age

“…Previous reports have observed an accumulation of fat within muscles during aging (Forsberg et al 1991;Frantzell and Ingelmark 1951;Hasson et al 2011), which also results in a loss of functional muscle mass. Using MRI, Kent-Braun et al (2000) have reported a similar trend of intramuscular fat (IMF) accumulation in the ankle dorsiflexor muscles with age in both genders.…”