High-intensity and progressive trials of resistance exercise have shown significant effects on BMD at vertebral and hip sites. Studies in general have shown that the exercise must be continued to maintain the benefit that the additional gain is lost within a few years of the program if the protocol is not continued. Assessment of skeletal muscle BAY 80-6946 using imaging Imaging offers the potential for an anatomic site-specific assessment of multiple

targets related to skeletal muscle physiology. Imaging has an important role in research studies of sarcopenia etiology and response to intervention. The primary imaging target in skeletal muscle mass assessment is lean body mass assessment by DXA, which involves use of standard clinical bone densitometers to decompose nonbone

tissue into lean and fat body mass components. Measurements may be obtained of total body lean and fat mass as well as regional measures in the central and appendicular skeleton. As this is an extremely widespread and well-known technology, which is commonly used in clinical studies in both bone and muscle research, we will refer the readers to several reviews that lay out the technical Selleckchem GSK126 considerations for DXA soft tissue assessment [112–116]. CT imaging may be employed to quantify bulk characteristics of muscle and body composition that are highly related to muscle strength and to overall functional ability in the elderly. In particular, CT imaging is widely used to study muscle and fat in epidemiologic studies of body composition. Typically, acquisitions have included single cross sections at the L1/2 or L4/5 intervertebral space to image body fat or volumetric measurements obtained in the abdomen and in the thigh, usually relating to the midthigh Carnitine palmitoyltransferase II or to a bony landmark [23, 83, 88, 117–121]. As shown in Fig. 4, the key variables quantified include the

total muscle CSA of the midthigh, the CSA values of the quadriceps and hamstrings, the total CSA of subcutaneous fat, and the attenuation coefficients of the total thigh muscle and the hamstrings and quadriceps separately. The CSA values of the total thigh muscle and quadriceps muscle are positively associated with increasing knee extensor strength [118]. The CSA declines with age, as does the muscle strength, and is smaller in females than in males [117–119]. Another property of great interest to the study of sarcopenia is the mean attenuation coefficient [23, 117–119], which is computed within all of the muscle regions after a threshold is applied to exclude depots of fat embedded within each muscle group. In elderly subjects, the mean attenuation coefficient, when calculated in this manner, has been shown histologically to correspond to fat accumulation within and between the muscle cells. The increasing fat infiltration into the muscle with aging may be an important, if not central, aspect of sarcopenia.