Longitudinal Changes in Muscle Mass and Function in Older Men at Increased Risk for Sarcopenia - The FrOST-Study.

BACKGROUND: Declines in muscle mass and function are inevitable developments of the advanced aging process. Corresponding dimensions of longitudinal changes in at-risk populations are still scarce although clinically relevant. The present study monitored changes in morphologic and functional sarcopenia criteria related to sarcopenia in older men with low muscle mass over a period of 24 months. OBJECTIVES: The main objective of the present study was to determine whether changes in muscle mass and function were comparable across the body. Our hypothesis was that both (1) fat free mass (FFM) and (2) function decline at a significantly higher rate in the lower versus the upper extremities. DESIGN: We conducted an observational study of 24 months. SETTING: Community dwelling men living in the area of Northern Bavaria were initially included in the Franconian Sarcopenic Obesity (FranSO) study by the Institute of Medical Physics University of Erlangen-Nürnberg, Germany. PARTICIPANTS: One hundred and seventy-seven (177) men (77.5±4.5 years) within the lowest skeletal muscle mass index (SMI) quartile of the FranSO study were included in the present 24 month analysis. MEASUREMENTS: Fat free mass (direct-segmental, multi-frequency Bio-Impedance-Analysis (DSM-BIA)), handgrip strength (hand-dynamometer) and 10-m habitual gait velocity (photo sensors) were assessed at baseline and 24-month follow-up. RESULTS: Lower extremity fat free mass (LEFFM: -2.0±2.4%), handgrip strength (-12.8±11.0%) and gait velocity (-3.5±9.0%) declined significantly (p<.001) during the follow-up period, while upper extremity FFM was maintained unchanged (UEFFM: 0.1±3.1%). Changes in LEFFM were significantly higher (p<.001) compared with UEFFM, however contrary to our expectation the decline in handgrip strength representing upper extremity muscle function was 3.7-fold higher (p<.001) than the decline in gait velocity. CONCLUSION: Medical experts involved in diagnosis, monitoring and management of sarcopenia should consider that parameters constituting morphologic and functional sarcopenia criteria feature different rates of decline during the aging process.

Changes of Maximum Leg Strength Indices During Adulthood a Cross-Sectional Study With Non-athletic Men Aged 19-91.

Age-related loss of muscle mass and function, also called sarcopenia, was recently added to the ICD-10 as an independent condition. However, declines in muscle mass and function are inevitable during the adulthood aging process. Concerning muscle strength as a crucial aspect of muscle function, maximum knee extension strength might be the most important physical parameter for independent living in the community. In this study, we aimed to determine the age-related decline in maximum isokinetic knee extension (MIES) and flexion strength (MIFS) in adult men. The primary study hypothesis was that there is a slight gradual decrease of MIES up to ≈age 60 years with a significant acceleration of decline after this "changepoint." We used a closed kinetic chain system (leg-press), which is seen as providing functionally more relevant results on maximum strength, to determine changes in maximum isokinetic hip/leg extensor (MIES) and flexor strength (MIFS) during adulthood in men. Apart from average annual changes, we aimed to identify whether the decline in maximum lower extremity strength is linear. MIES and MIFS data determined by an isokinetic leg-press of 362 non-athletic, healthy, and community-dwelling men 19-91 years old were included in the analysis. A changepoint analysis was conducted based on a multiple regression analysis adjusted for selected co-variables that might confound the proper relationship between age and maximum strength. In summary, maximum isokinetic leg-strength decline during adulthood averaged around 0.8-1.0% p.a.; however, the reduction was far from linear. MIES demonstrated a non-significant reduction of 5.2 N/p.a. (≈0.15% p.a.) up to the estimated breakpoint of 52.0 years and an accelerated loss of 44.0 N/p.a. (≈1.3% p.a.; p < 0.001). In parallel, the decline in MIFS (10.0 N/p.a.; ≈0.5% p.a.) prior to the breakpoint at age 59.0 years was significantly more pronounced. Nevertheless, we observed a further marked accelerated loss of MIFS (25.0 N/p.a.; ≈1.3% p.a.) in men ≥60 years. Apart from the "normative value" and closed kinetic chain aspect of this study, the practical application of our results suggests that sarcopenia prophylaxis in men should be started in the 5th decade in order to address the accelerated muscle decline of advanced age.