Location: Jean Mayer Human Nutrition Research Center On AgingTitle: Circulating interleukin-6 is associated with skeletal muscle strength, quality, and functional adaptation with exercise training in mobility-limited older adults
|GROSICKI, GREGORY - Georgia Southern University|
|BARRETT, BRITTANY - Jean Mayer Human Nutrition Research Center On Aging At Tufts University|
|ENGLUND, DAVIS - Jean Mayer Human Nutrition Research Center On Aging At Tufts University|
|LIU, CHRISTINE - Jean Mayer Human Nutrition Research Center On Aging At Tufts University|
|TRAVISON, THOMAS - Hebrew Senior Life|
|CEDERHOLM, TOMMY - Uppsala University|
|KOOCHEK, AFSANEH - Uppsala University|
|VON BERENS, ASA - Uppsala University|
|GUSTAFSSON, THOMAS - Karolinska Institute|
|BENARD, TOWNSEND - Jean Mayer Human Nutrition Research Center On Aging At Tufts University|
|REID, KIERAN - Jean Mayer Human Nutrition Research Center On Aging At Tufts University|
|FIELDING, ROGER - Jean Mayer Human Nutrition Research Center On Aging At Tufts University|
Submitted to: The Journal of Frailty and Aging
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/31/2019
Publication Date: 9/13/2019
Citation: Grosicki, G.J., Barrett, B.B., Englund, D.A., Liu, C., Travison, T.G., Cederholm, T., Koochek, A., Von Berens, A., Gustafsson, T., Benard, T., Reid, K.F., Fielding, R.A. 2019. 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 and Aging. 9:57-63. https://doi.org/10.14283/jfa.2019.30.
Interpretive Summary: Advancing age is characterized by chronic, low-grade inflammation that is suspected to contribute to reductions in skeletal muscle size and performance. This study investigated relationships between muscle health and inflammation (i.e., Interleukin-6) in older adults with compromised functional capacity. Among these disability-prone individuals, inflammation was predictive of muscle fat infiltration, weakness and poor physical function (e.g., stair climb ability). Moreover, individuals who were able to reduce inflammation via exercise training exhibited the greatest improvements in physical function (e.g., walking speed). Collectively, these findings underscore the functional relevance of heightened inflammation in older adults and the value of therapeutic strategies seeking to reduce inflammatory levels.
Technical Abstract: Background: 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. Objectives: To investigate relationships between circulating IL-6, skeletal muscle health and exercise adaptation in mobility-limited older adults. Design: Randomized controlled trial. Setting: Exercise laboratory on the Health Sciences campus of an urban university. Participants: 99 mobility-limited (Short Physical Performance Battery (SPPB) =9) older adults. Intervention: 6-month structured physical activity with or without a protein and vitamin D nutritional supplement. Measurements: 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. Results: 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). Conclusions: 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.