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RELATIONSHIP OF PHYSICAL FRAILTY TO PHOSPHOCREATINE RECOVERY IN MUSCLE AFTER MILD EXERCISE STRESS IN THE OLDEST-OLD WOMEN

R. Varadhan, D.W. Russ, R.E. Gabr, J. Huang, R.R. Kalyani, Q.-L. Xue, A.R. Cappola, K.Bandeen-Roche, L.P. Fried

Background: Physical frailty is a clinical syndrome associated with aging and manifesting as slowness, weakness, reduced physical activity, weight loss, and/or exhaustion. Frail older adults often report that their major problem is “low energy”, and there is indirect evidence to support the hypothesis that frailty is a syndrome of dysregulated energetics. We hypothesized that altered cellular energy production underlies compromised response to stressors in the frail. Methods: We conducted a pilot study to assess muscle energetics in response to a mild isometric exercise challenge in women (n=30) ages 84-93 years. The frailty status was assessed by a validated physical frailty instrument. Localized phosphorus (P31) magnetic resonance spectroscopy with a 1.5T magnet was used to assess the kinetics of Phosphocreatine recovery in the tibialis anterior muscle following maximal isometric contraction for 30 seconds. Results: Phosphocreatine recovery following exertion, age-adjusted, was slowest in the frail group (mean=189 sec; 95%CI: 150,228) compared to pre-frail (mean=152 sec; 95%CI: 107,197) and nonfrail subjects (mean=132 sec; 95%CI: 40,224). The pre-frail and frail groups had 20 sec (95%CI: -49,89) and 57 sec (95%CI: -31,147) slower phosphocreatine recovery, respectively, than the non-frail. This response was paralleled by dysregulation in glucose recovery in response to oral glucose tolerance test in women from the same study population. Conclusions: Impaired muscle energetics and energy metabolism might be implicated in the physical frailty syndrome.

CITATION:
R. Varadhan ; D.W. Russ ; R.E. Gabr ; J. Huang ; R.R. Kalyani ; Q.-L. Xue ; A.R. Cappola ; K.Bandeen-Roche ; L.P. Fried (2019): Relationship of physical frailty to phosphocreatine recovery in muscle after mild exercise stress in the oldest-old women. The Journal of Frailty and Aging (JFA). http://dx.doi.org/10.14283/jfa.2019.21

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