A review of studies that used B mode Ultrasound to estimate age-related changes in anterior thigh skeletal muscle thickness across the adult lifespan.

Background
The purpose of this review was to synthesise and determine the age-related change per annum in muscle thickness of the anterior thigh across the adult lifespan.

Methods
Electronic databases (PubMed, SPORTDiscus and MEDLINE) were searched for primary studies that were screened for eligibility.

Results
Following screening against eligibility criteria, 27 studies were included in the quantitative analysis. Linear regression revealed a 0.02 cm (95% CI: - .01, -.03, p<0.05) decline in mean muscle thickness per annum from 18-80 years of age, a 0.03cm (95% CI: -.01 to -.05) decline per annum between 20 to 49 years of age and a 0.05cm (95% CI: -.03, - .07) decline per annum between 50 to 80 years of age. There was a 1.5cm (t (25) = 6.12, p<0.05; 95% CI= .98- 1.97cm) mean difference in muscle thickness between the youngest (18-29yrs: 5.13cm ± 0.38) and oldest adults (70-80yrs) 3.63cm ± 0.63). There was no difference in the rate of decline of mean muscle thickness between males (-0.05cm/annum, 95% CI= -.08, -.02) and females (-0.04cm/annum, 95% CI= -.07, -.02). There was a larger difference in anterior thigh muscle thickness between the youngest and oldest in females (4.98cm vs. 3.34cm, 33%, p < 0.05) compared with males (5.23cm vs. 3.98cm, 24%, p <0.05).

Conclusion
Mean anterior thigh thickness was estimated to decrease at a rate of 0.02cm per annum and this rate of decrease was greater after 50 years of age. Females were more susceptible to age-related reductions in anterior thigh muscle thickness than males.

http://dx.doi.org/10.1016/j.aggp.2024.100037