E-Poster Presentation ESA-SRB-ANZBMS 2021

The relationships between muscle mass and function with bone remodelling markers in older adults: effects of acute aerobic and resistance exercises (#762)

Cassandra Smith 1 2 , Danielle Hiam 3 , Alexander Tacey 1 2 , Xuzhu Lin 1 , Mary N Woessner 1 , Navabeh Zarekookandeh 1 , Joshua R Lewis 4 5 , Marc Sim 4 5 , Markus Herrmann 6 , Gustavo Duque 2 7 , Itamar Levinger 1 2
  1. Institute for Health and Sport (iHeS), Victoria University, Melbourne, VIC, Australia
  2. Australian Institute for Musculoskeletal Sciences (AIMSS), University of Melbourne, Melbourne, VIC, Australia
  3. Institute for Physical Activity and Nutrition (IPAN), , Deakin University, Melbourne, VIC, Australia
  4. School of Medical and Health Sciences, Edith Cowan University, Perth, Western Australia, Australia
  5. Medical School, University of Western Australia, Perth, WA, Australia
  6. Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, Graz, Austria
  7. Department of Medicine- Western Health, University of Melbourne, Melbourne, VIC, Australia

Purpose: Age-related muscle mass/strength loss affects independence and quality of life. Bone-muscle crosstalk is potentially mediated by bone remodelling markers (BRMs) including osteocalcin (OC). We tested the hypothesis that BRMs are correlated with baseline muscle mass/function which would predict BRM-responses after acute exercise. We also assessed the relationship between BRMs and insulin resistance (HOMA-IR).

Methods: Thirty-five older adults (25 women/10 men, 72±6 yrs) participated. Baseline assessments included body composition (DXA), muscle strength (grip, leg press) and physical performance (PPT, timed-up-and-go; gait speed, stair ascend/descend). Leg muscle quality (LMQ=leg press/leg lean mass) and stair climb power (SCP=force x velocity) were calculated. Participants performed (randomised) 30 mins aerobic (cycling 70%HRPeak) and resistance exercise (leg press 70%RM, jumping). C-terminal telopeptide of type I collagen (CTX), procollagen of type I propeptide (P1NP), total (t)OC, undercarboxylated (uc)OC, glucose, insulin and HOMA-IR were assessed pre/post-exercise. Data was analysed using linear mixed models and beta-regressions.

Results: No difference in BRMs-responses to AE and RE, therefore data analysed together. Poorer PPT was related to lower baseline ß-CTX, P1NP and ucOC (all p<.05). Higher strength (LMQ, grip and leg) was related to higher baseline P1NP (all p<.05). Exercise decreased ß-CTX, tOC, insulin and HOMA-IR (all p<.05).  ucOC remained unchanged. Participants  with higher baseline muscle strength (SCP, LMQ, leg and grip) had lower post-exercise ß-CTX and tOC (all p <.05). Higher baseline ß-CTX, P1NP, tOC and ucOC was associated with lower post-exercise insulin resistance (HOMA-IR) (all p<.05).

Conclusions: Older adults with higher baseline BRMs are linked to greater muscle function and lower insulin resistance. Acute exercise decreases ß-CTX and tOC, and higher baseline muscle strength was related to lower responses of these specific BRMs. Despite mechanisms behind the specific component of bone-muscle crosstalk remaining unclear, BRMs may be used to identify individuals with poorer muscle function and insulin sensitivity.