Abstract
Triceps surae (TS) muscle volume can be estimated in young adults by only considering the maximal anatomical cross-sectional area (ACSAmax) and the length of the muscle due to the presence of a constant muscle-specific shape factor. This study aimed to investigate if this simplified muscle volume assessment is also applicable in older adults or if muscle-specific shape changes with aging. MRI sequences were taken from the dominant leg of 21 older female adults. The boundaries of all three TS muscles (SOL, soleus; GM, gastrocnemius medialis; GL, gastrocnemius lateralis) were manually outlined in transverse image sequences, and muscle volume for each muscle was calculated as the integral of the obtained cross-sectional areas of the contours along the whole length of the muscle (measured volume) and, in addition, by using the average muscle-specific shape factors of each muscle obtained from the ratio of the measured volume and the product of ACSAmax and the muscle length (estimated volume). There were no differences in the measured and estimated muscle volumes (SOL: 357.7 ± 61.8 vs. 358.8 ± 65.3 cm3; GM: 179.5 ± 32.8 vs. 179.8 ± 33.3 cm3; GL: 90.2 ± 15.9 vs. 90.4 ± 14.8 cm3). However, when using the reported shape factors of younger adults instead, we found a significant (p < 0.05) overestimation of muscle volume for SOL and GM with average RMS differences of 6.1 and 7.6%, respectively. These results indicate that corrections of muscle-specific shape factors are needed when using the previously proposed simplified muscle volume assessment as aging may not only be accompanied with muscle atrophy but also changes in the shape of skeletal muscle.
Highlights
Muscle volume reportedly undergoes tremendous changes with maturation (O’Brien et al, 2010), several pathologies (Zoabli et al, 2008; Ji et al, 2013), mechanical loading (Folland and Williams, 2007), immobilization (Oates et al, 2010), or aging (Morse et al, 2005a)
A significant (p < 0.01) muscle effect was found for all analyzed morphological parameters within the triceps surae (TS) with the soleus muscle (SOL) showing the largest muscle length, ACSAmax, and volume, followed by the gastrocnemius medialis (GM) and gastrocnemius lateralis (GL) (Table 1, Figure 2)
The maximum anatomical cross-sectional area (ACSA) was located at 59.3 ± 3.5, 75.0 ± 4.3, and 80.6 ± 5.1% of the shank length for the SOL, GM, and GL, respectively, and the inter-subject variability of the ACSAmax location ranged between 5.8 and 6.4%
Summary
Muscle volume reportedly undergoes tremendous changes with maturation (O’Brien et al, 2010), several pathologies (Zoabli et al, 2008; Ji et al, 2013), mechanical loading (Folland and Williams, 2007), immobilization (Oates et al, 2010), or aging (Morse et al, 2005a). This is of functional relevance as muscle volume is an important determinant of the muscle mechanical power (O’Brien et al, 2009) and physical performance (Chelly and Denis, 2001). The generalizability of the reported TS shape factors of young adults’ muscles to muscles that underwent atrophy due to aging cannot be assumed a priori and needs to be verified
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
