Circulating Interleukin-6 is Associated with Skeletal Muscle Strength, Quality, and Functional Adaptation with Exercise Training in Mobility-Limited Older Adults
The Journal of Frailty & Aging
Human aging is characterized by a chronic, low-grade inflammation suspected to contribute to reductions in skeletal muscle size, strength, and function. Inflammatory cytokines, such as interleukin-6 (IL-6), may play a role in the reduced skeletal muscle adaptive response seen in older individuals.
To investigate relationships between circulating IL-6, skeletal muscle health and exercise adaptation in mobility-limited older adults.
Randomized controlled trial.
Exercise laboratory on the Health Sciences campus of an urban university.
99 mobility-limited (Short Physical Performance Battery (SPPB) ≤9) older adults.
6-month structured physical activity with or without a protein and vitamin D nutritional supplement.
Circulating IL-6, skeletal muscle size, composition (percent normal density muscle tissue), strength, power, and specific force (strength/CSA) as well as physical function (gait speed, stair climb time, SPPB-score) were measured pre- and post-intervention.
At baseline, Spearman’s correlations demonstrated an inverse relationship (P<0.05) between circulating IL-6 and thigh muscle composition (r = -0.201), strength (r = -0.311), power (r = -0.210), and specific force (r = -0.248), and positive association between IL-6 and stair climb time (r = 0.256; P<0.05). Although the training program did not affect circulating IL-6 levels (P=0.69), reductions in IL-6 were associated with gait speed improvements (r = -0.487; P<0.05) in “higher” IL-6 individuals (>1.36 pg/ml). Moreover, baseline IL-6 was inversely associated (P<0.05) with gains in appendicular lean mass and improvements in SPPB score (r = -0.211 and -0.237, respectively).
These findings implicate age-related increases in circulating IL-6 as an important contributor to declines in skeletal muscle strength, quality, function, and training-mediated adaptation. Given the pervasive nature of inflammation among older adults, novel therapeutic strategies to reduce IL-6 as a means of preserving skeletal muscle health are enticing.
Grosicki, Gregory James, Brittany B. Barrett, Davis A. Englund, Christine K. Liu, Thomas G. Travison, Tommy Cederholm, Afsaneh Koochek, Åsa von Berens, Thomas Gustafsson, T. Benard, Kieran Reid.
"Circulating Interleukin-6 is Associated with Skeletal Muscle Strength, Quality, and Functional Adaptation with Exercise Training in Mobility-Limited Older Adults."
The Journal of Frailty & Aging, 9: 57-63: Springer.
doi: 10.14283/jfa.2019.30 source: https://link.springer.com/article/10.14283/jfa.2019.30