Analyzing feed-forward loop relationship in aging phenotypes: Physical activity and physical performance

Arindam RoyChoudhury, Thuy Tien L. Dam, Ravi Varadhan, Qian Li Xue, Linda P. Fried

Research output: Contribution to journalArticlepeer-review


We present evidence of feed-forward loop relationships and positive association between physical activity and performance levels, which are components of frailty, using measures from 431 high functioning women initially aged 70-79 years followed over 7 visits. Physical activity levels were assessed using a questionnaire. Grip strength was measured using a handheld dynamometer and usual walking speed was measured over 4-m. The results suggest that a reduction in physical activity would not only degrade physical performance, but it would further reduce physical activity through declines in physical performance. As both physical activity and physical performance impact frailty, improvement of physical activity could help reduce frailty directly as well as indirectly via improved physical performance. Our findings support a priori hypothesis that feed-forward loops are present in the phenotype of frailty, which is due to dysregulated energetics. A methodologically broader implication is that we introduce modeling and analysis of feed-forward loop data here. The feed-forward loop, as we define it, is different from the concept of feedback loops used in biochemical systems. Generalizing our model of two-variable feed-forward loop, three, four or multivariable feed-forward loop can be applied to other biological systems.

Original languageEnglish (US)
Pages (from-to)5-11
Number of pages7
JournalMechanisms of Ageing and Development
StatePublished - Aug 26 2014


  • Dynamical systems
  • Frailty
  • Physical activity
  • Strength
  • Walking

ASJC Scopus subject areas

  • Aging
  • Developmental Biology


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