Characterizing upper limb muscle volume and strength in older adults: A comparison with young adults

Abstract

Aging is associated with loss of muscle volume (MV) and force leading to difficulties with activities of daily living. However, the relationship between upper limb MV and joint strength has not been characterized for older adults. Quantifying this relationship may help our understanding of the functional upper limb declines older adults experience. Our objective was to assess the relationship between upper limb MV and maximal isometric joint moment-generating capacity (IJM) in a single cohort of healthy older adults (age≥65 years) for 6 major functional groups (32 muscles). MV was determined from MRI for 18 participants (75.1±4.3 years). IJM at the shoulder (abduction/adduction), elbow (flexion/extension), and wrist (flexion/extension) was measured. MV and IJM measurements were compared to previous reports for young adults (28.6±4.5 years). On average older adults had 16.5% less total upper limb MV compared to young adults. Additionally, older adult wrist extensors composed a significantly increased percentage of upper limb MV. Older adult IJM was reduced across all joints, with significant differences for shoulder abductors (p<0.0001), adductors (p=0.01), and wrist flexors (p<0.0001). Young adults were strongest at the shoulder, which was not the case for older adults. In older adults, 40.6% of the variation in IJM was accounted for by MV changes (p≤0.027), compared to 81.0% in young adults. We conclude that for older adults, MV and IJM are, on average, reduced but the significant linear relationship between MV and IJM is maintained. These results suggest that older adult MV and IJM cannot be simply scaled from young adults.

Is My Model Good Enough? Best Practices for Verification and Validation of Musculoskeletal Models and Simulations of Movement

“…Using MRI-based PCSAs with known size relationships should avoid the need to artificially increase the specific tension parameter to inflate muscle strengths. The relative distribution of muscle strengths can change as a function of age in the upper extremity [115] and lower extremity [116], though linear scaling laws hold among individuals of similar age. MRI-derived volumes will allow development of improved age-matched musculoskeletal models.…”

An age- and gender-related three-dimensional analysis of rotator cuff transverse force couple volume ratio in 304 shoulders

“…Vidt et al [23] observed a significant decrease in the musculature of the upper extremities in patients over 65 years of age relative to younger patients. In our study, analyzing the RCTFC muscle volume on non-pathologic shoulders, we found significant differences in the muscle volume of the rotator cuff in the different age groups (Table 2).…”

“…These two observers were blinded in space and time, with 3 weeks between the measurements of one observer and the other. For each thoracic CT, the muscle limits in each projection were determined, and manual segmentation was performed for the volume, using a technique similar to those reported in related studies [6,22,23]. However, we modified this technique as we first segmentate the muscle in an oblique reconstruction, parallel to the muscle studied (subscapularis, infraspinatus and teres minor); subsequently, the remaining volume was manually segmented in coronal, sagittal, and axial projections, confirming that the muscle was segmented in its totality in the four projections ( Fig.…”

“…Rotator cuff muscle volume has been quantified by employing various imaging techniques in patients [6,11,12,17,23,24], cadavers [13,16,21,22], sheep [5] and primates [18,20]. Piepers et al [17] quantified the muscle volume correlation of the subscapularis muscle regarding the teres minor and infraspinatus in a series of 27 computed tomography scans in 21 patients, finding no significant differences among RCTFC components in healthy shoulders.…”

“…Vidt et al [23] determined the variations of muscle volume in older adults ([65 years of age) and young adults in 18 patients using magnetic resonance muscle segmentations, reporting significant reductions in muscle volume and strength in the older adults. At present, human studies that quantify muscle volume and the ratio existing between the RCTFC muscles present various limitations because they were performed on small samples and their results fail to describe the existing variations regarding age and gender.…”