Sarcopenia Especially Loss of Strength Indicates Age Related Mortality

Strength as a product of muscle mass, neuromuscular control and energetics is a better predictor of impending mortality.

Age related sarcopenia is a result of decreased regeneration of muscle mass but also relates to the brain body network disconnection syndrome and the decreased strength and endurance.

BDNF increases muscle endurance and network connectivity.

Exercise and fasting increase BDNF.

Ursolic acid increases strength and is an exercise and fasting mimetic.  Ursolic acid likely increases BDNF.

Exercise, fasting and Ursolic acid is likely synergistic in increasing strength, reducing dementia (brain network disconnection syndrome)  and reducing mortality.

https://biomedgerontology.oxfordjournals.org/content/61/1/72.full

Strength, But Not Muscle Mass, Is Associated With Mortality in the Health, Aging and Body Composition Study Cohort

1. Anne B. Newman ¹ , 
2. Varant Kupelian ² , 
3. Marjolein Visser ³ , 
4. Eleanor M. Simonsick ⁴ , 
5. Bret H. Goodpaster ⁵ , 
6. Stephen B. Kritchevsky ⁶ , 
7. Frances A. Tylavsky ⁷ , 
8. Susan M. Rubin ⁸ , 
9. Tamara B. Harris ⁴ and 
10. on Behalf of the Health, Aging and Body Composition Study Investigators

+ Author Affiliations

1. Address correspondence to Anne B. Newman, MD, MPH, University of Pittsburgh, Department of Epidemiology, 130 N. Bellefield Avenue, Room 532, Pittsburgh, PA 15213. E-mail: newmana@edc.pitt.edu

• Received January 28, 2005.
• Accepted July 30, 2005.

Abstract

Background. Although muscle strength and mass are highly correlated, the relationship between direct measures of low muscle mass (sarcopenia) and strength in association with mortality has not been examined.

Methods. Total mortality rates were examined in the Health, Aging and Body Composition (Health ABC) Study in 2292 participants (aged 70–79 years, 51.6% women, and 38.8% black). Knee extension strength was measured with isokinetic dynamometry, grip strength with isometric dynamometry. Thigh muscle area was measured by computed tomography (CT) scan, and leg and arm lean soft tissue mass were determined by dual energy x-ray absorptiometry (DXA). Both strength and muscle size were assessed as in gender-specific Cox proportional hazards models, with age, race, comorbidities, smoking status, level of physical activity, fat area by CT or fat mass by DXA, height, and markers of inflammation, including interleukin-6, C-reactive protein, and tumor necrosis factor-α considered as potential confounders.

Results. There were 286 deaths over an average of 4.9 (standard deviation = 0.9) years of follow-up. Both quadriceps and grip strength were strongly related to mortality. For quadriceps strength (per standard deviation of 38 Nm), the crude hazard ratio for men was 1.51 (95% confidence interval, 1.28–1.79) and 1.65 (95% confidence interval, 1.19–2.30) for women. Muscle size, determined by either CT area or DXA regional lean mass, was not strongly related to mortality. In the models of quadriceps strength and mortality, adjustment for muscle area or regional lean mass only slightly attenuated the associations. Further adjustment for other factors also had minimal effect on the association of quadriceps strength with mortality. Associations of grip strength with mortality were similar.

Conclusion. Low muscle mass did not explain the strong association of strength with mortality, demonstrating that muscle strength as a marker of muscle quality is more important than quantity in estimating mortality risk. Grip strength provided risk estimates similar to those of quadriceps strength.

OLDER adults with reduced muscle strength have higher mortality (1–6). Muscle strength is closely related to the absolute quantity of muscle mass, which is also reduced with aging (7–10). This decrease in muscle mass (sarcopenia) is thought to contribute to the development of functional limitations and disability in old age (11,12), and potentially might explain part of the association between strength and mortality. Previous studies (1–4) have used only weight, creatinine excretion, or derived anthropometric measures to estimate muscle mass. Thus the role of muscle mass in mediating the strength–mortality association has not been adequately determined.

Strength might also predict mortality because it is reduced with disease and deconditioning. For example, lower extremity arterial ischemia can cause lower muscle strength and function (13). Pain from osteoarthritis may prevent activity resulting in atrophy from disuse. Intervention studies show the potential for large improvements in strength with small increases in lean mass (14), illustrating the importance of activity and exercise. Markers of inflammation are also related to lower strength (15) and lean mass, as well as to a decline in strength (16). However, in the Women's Health and Aging Study, comorbidity and inflammatory markers did not explain the association of lower grip strength with mortality (3).

The Health, Aging and Body Composition (Health ABC) Study was designed to determine the role of body composition changes in the risk of poor health outcomes including death and functional limitation in older adults. In this report, we sought to determine whether low muscle mass, measured with computed tomography (CT) scanning and dual energy x-ray absorptiometry (DXA), would explain an association of strength with mortality with and without adjusting for hypothesized causes of sarcopenia, including physical activity, disease, and inflammatory markers. Finally, we were able to compare associations on the basis of isokinetic quadriceps strength versus isometric grip strength