O040 - IMPROVEMENTS IN MUSCLE-SPECIFIC STRENGTH FOLLOWING A MULTIMODAL BEHAVIORAL INTERVENTION IN OBESITY AND OSTEOARTHRITIS

O040

IMPROVEMENTS IN MUSCLE-SPECIFIC STRENGTH FOLLOWING A MULTIMODAL BEHAVIORAL INTERVENTION IN OBESITY AND OSTEOARTHRITIS

F. T. Vieira^1,*, K. Godziuk^1,2, M. Forhan³, C. M. Prado¹

¹Agricultural, Food & Nutritional Science, University of Alberta, Edmonton, Canada, ²Physical Therapy and Rehabilitation Science, University of California, San Francisco, San Francisco, United States, ³Occupational Science & Occupational Therapy, University of Toronto, Toronto, Canada

Rationale: Muscle-specific strength (MSS) indicates how efficiently a muscle generates force relative to its size and may provide more meaningful insights into muscle health than muscle mass or strength alone. This study investigated changes in MSS following a multimodal behavioral intervention (MBI) in individuals aged 40-75 years with BMI≥35kg/m² and knee osteoarthritis.

Methods: Secondary analysis of the immediate post-intervention timepoint from the POMELO RCT, which compared a MBI to usual care at 9 months. The 12-week MBI included whole-body resistance exercise 3x/wk, nutrition counseling, and biweekly nutrition and self-management education. Participants with complete body composition (DXA) and muscle function (handgrip strength [HGS], 30-s sit-stand test [STS]) at 12 weeks were included. Groups were similar at baseline. Upper limb MSS (MSS_UL) was defined as the ratio of HGS:arms lean soft tissue (LST), and lower limb MSS (MSS_LL) as the ratio of STS:legs LST.

Results: Thirty-three individuals had full data at week 12 (n=16 intervention); 72.7% female, mean age 65.2±7.1y and BMI  42.5±4.8kg/m². ANCOVA, adjusted for baseline, revealed a positive effect of the intervention compared to usual care on MSS_LL (adjusted mean [AM] ± standard error [SE]: 0.61±0.03 vs 0.45±0.03 rep/kg, p=0.008), with a large effect size (partial eta squared=0.220). No effect was observed on MSS_UL (AM±SE: 5.22±0.12 vs 4.85±0.11 kg/kg, p=0.983). Notably, STS also independently improved post-intervention compared to usual care, while HGS and LST did not.

Conclusion: MSS in the lower extremity improved following this 12-week MBI, driven by enhancements in muscle function rather than detectable changes in muscle mass. No changes were observed in the upper extremity. MSS_LL may be a useful indicator of muscle capacity, complementing traditional measures of muscle mass or strength in adults with obesity and osteoarthritis.

Disclosure of Interest: F. Vieira: None declared, K. Godziuk Grant / Research Support from: Rheumatology Research Foundation; Bethel Musculoskeletal Research Center/Orthopaedic Research Society; Canadian Institutes of Health Research, M. Forhan: None declared, C. Prado Other: Speaker engagement: Abbott Nutrition, Nutricia, Nestle Health Science, Novo Nordisk