Thigh composition in young and elderly men determined by computed tomography

Abstract

Computed tomography (CT) was used to quantify components of the thigh in young (n = 13) and elderly (n = 11) men. Cross-sectional areas (CSA) of the total limb, total muscle plus bone, quadriceps compartment, hamstring compartment and bone were measured at each of five scan sites along the length of the thigh. Non-muscle tissue (NMT) areas within the muscle compartments were measured using changes in density based on Hounsfield units. Skin plus subcutaneous fat areas and quadriceps and hamstring lean muscle areas were calculated by subtraction. Geometric formulae were used to calculate related volumes for each thigh component. Volumes were also predicted from regression equations employing thigh length and component CSA from single mid-limb CT scans. The results showed that while total thigh CSA was not different in elderly men, they had significantly smaller total muscle plus bone (13.0%), and quadriceps (26.4%), and hamstring (17.9%) muscle areas. The elderly men also had significantly greater CSA for skin plus subcutaneous fat (37.6%), and for NMT in the quadriceps (59.4%) and hamstring (127.3%) muscle compartments. These results suggest that comparisons of relative leg muscle strength between young and elderly men may be misleading due to the decrease in actual muscle tissue associated with ageing. Appropriate quantification of muscle size and CSA must be carried out before such comparisons can be meaningful.

Modelling the influence of fat-free mass and physical activity on the decline in maximal oxygen uptake with age in older humans

“…The estimation of body density provided by the Durnin & Womersley (1974) equation was based on 24 males and 37 females aged 50-72 years and therefore may be less appropriate for our sample of older adults aged 55-86 years. In addition, the exclusion of muscle fat content (Rice et al 1990;Overend et al 1992) and intra-abdominal fat (Han et al 1997), which is known to increase with age, and the inclusion of bone in our measurements would modify the subsequent determination of FFM. These factors notwithstanding, the measurement appeared to be sensitive and resulted in a significant contribution of FFM to the decline in ýOµ,max and the difference in that variable between men and women.…”

Anaerobic power of the arms and legs of young and older men

“…For PP, the results of the present study, 1076 and 807 W for the young and older groups, respectively, were similar to those in the study of Makrides et al (1985) who reported 1037 W for healthy, young males and 760 W for healthy older subjects over 55 years. An additional comparison may be made with our previous work that determined critical power and anaerobic work capacity in young and older subjects (Overend et al 1992). In the present study, the difference found for leg PP and MP (•25%), is smaller than the difference of 40% observed in anaerobic work capacity between subjects of similar ages (25 and 71 years).…”

“…In our study, lean thigh and leg volumes were 12-14% lower in old versus young, which accounted for only approximately one-half of the loss in MP or PP. Using computed tomography, Rice et al (1989) andOverend et al (1992) found lower limb muscle areas to be approximately 26% smaller in the old when compared with the young, because of significant regions of non-muscle tissue. If this were the case in the present study, the decrease in power output of the older group would be fully explained by loss of muscle mass.…”

Modelling the influence of age, body size and sex on maximum oxygen uptake in older humans

“…As women tend to have a greater proportion of overall body fat, this reduction in sex difference is understandable. However, one feature that could confound interpretation is that older muscle shows changes in the muscle-to-fat content ratio (Rice et al 1990;Overend et al 1992). Older men demonstrate increased interstitial fat content in addition to the increases in subcutaneous fat.…”