the life cycle, but science is now being used to treat the deterioration of the human body so that the aging population can live with independence and comfort. Difference from sarcopenia Sarcopenia is defined as loss of muscle tissue as a natural part of the aging process. This does not include loss of muscle strength, which is defined by Dynapenia. Muscle strength appears to be a critical component in maintaining physical function, mobility, and vitality in old age, which is why it's imperative to identify and study contributing factors of Dynapenia. A longitudinal study on the age-related changes in muscle strength, quality, and inter muscular fat showed an increase in adipose tissue infiltration of mid thigh skeletal muscle in both men and women ranging between 70 and 79 years-old during a 5-year period. The increase in fatty tissue infiltration occurred regardless of changes in weight or subcutaneous thigh adipose tissue. The study also found that the decrease in muscle strength due to aging was 2-5 times greater than the loss of muscle size. These results demonstrate the age-related progression of muscle weakness and muscular fat infiltration regardless of changes in muscle mass or subcutaneous fat, reinforcing that muscle quality is lost with aging. Signs and symptoms The age-associated deterioration of force-generating properties of skeletal muscles can be directly associated with increased risk of physical disability, functional impairments, and increased mortality. Dynapenia can contribute to increased risk of falling as well as feeling weak and/or fatigued. With regard to the relation of higher levels of muscular strength to a lower risk of premature death, studies by Newman et al. have shown that grip and knee extensor muscle strength are strongly correlated with mortality. For women, they observed crude hazard ratios of 1.84 for grip strength and 1.65 for knee extensor strength. For men, they observed crude hazard ratios of 1.36 for grip strength and 1.51 for knee extensor strength. More recent studies by Xue et al. have observed that faster decline in hip flexor and grip strengths individually predicted mortality after accounting for potential contributors. Manini et al. recently conducted an informal meta-analysis that showed significant correlation between low levels of muscle strength and poor physical performance and/or physical disability in 90% of the studies. Together, these studies provide evidence that dynapenia in older adults is strongly correlated with increased risk of physical disabilities and mortality, and decreased physical function. Diagnosis