Sensory motor function is a combination of not only muscle strength, but motor unit recruitment HSP signaling pathway and rate of muscle contraction [44]. For example, recovery of balance following sudden perturbations requires a quick and powerful reflex response to overtake the falling momentum [45]. There was an overall decline in grip strength from

44 to 102 wk. of age. When normalized to body mass however, grip strength declined from 44 to 60 wk. only in the control, but not in the HMB condition. Moreover, normalized grip strength increased by 23% in the old HMB condition from 86 to 102 wk. of age. In addition, incline plane performance increased from young to middle aged rats that were administered HMB. Our results on overall functionality concur with Flakoll et al. [9] who previously demonstrated that 12 wk. of a cocktail containing HMB (also contained Arginine and Lysine)

significantly increased grip strength, leg extension force, as well as get up-and-go performance in older adults. Finally, changes in functionality and strength without detectable changes in LBM may indicate an increase in muscle quality. However, this is currently speculative and would need to be verified by future research. Myofiber dimensions Previous research with HMB supplementation has been restricted to indirect measures of muscle tissue which include caliper measurements [46, 47], DXA analysis SAR245409 research buy [38, 48], and limb circumference measures [9]. However, the hallmark of sarcopenia is a decline in muscle mass and then ultimately in myofiber dimensions. To our knowledge, our study is unique as we are the first to view actual changes

in muscle cellular dimensions following HMB Quinapyramine administration throughout senescence. In particular, we employed the diffusion tensor imaging (DTI) technique, which uses a powerful magnet at the NHMFL. This technique has been validated for studying changes in myofiber dimensions including myofiber length and cross sectional area (CSA) following ischemia reperfusion injury [26, 49, 50]. As predicted, no changes occurred in myofiber dimensions from 44 to 60 wk. of age. While sarcopenia was evident in the 86-wk and 102-wk control conditions, both λ 2 and λ 3, indicative of myofiber CSA were relatively maintained in the soleus and gastrocnemius muscles of rats consuming HMB. Our results are consistent with previous work from Flakoll [9] and Bair et al. [38] who found that a cocktail containing HMB was able to counter age-related losses in limb circumference. These results are also consistent with several additional muscle wasting models which demonstrated HMB could blunt muscle loss during sepsis [51], cancer [16], limb immobilization [21], and in critically ill trauma patients [52].