Acetaminophen and Impaired Musculoskeletal Adaptations to Exercise Training

• Change in Total Body Fat-free Mass [ Time Frame: 16 weeks ] [ Designated as safety issue: No ]
  change from baseline to 16 weeks in fat-free mass measured by DXA (Hologic Discovery W, version 12.6)
  
  

• Change in Total Body Fat Mass [ Time Frame: 16 weeks ] [ Designated as safety issue: No ]
  Change from baseline to 16 weeks in total body fat mass.
  
  
• Changes in Upper Body Strength. [ Time Frame: 16 weeks ] [ Designated as safety issue: No ]
  Strength was measured using the one-repetition maximum method. Upper body strength was a composite of bench press, overhead press, seated row, and lateral pull-down strength.
  
  
• Change in Lower Body Strength [ Time Frame: 16 weeks ] [ Designated as safety issue: No ]
  Strength was measured using the one-repetition maximum method. Lower body strength was a composite of knee flexion, knee extension, and leg press strength.
  
  

The commonly used pain relievers acetaminophen and ibuprofen may impair musculoskeletal adaptations to progressive resistance exercise training by inhibiting exercise-induced muscle protein synthesis.

To test the hypothesis that acetaminophen and ibuprofen would diminish training-induced increases in fat-free mass, untrained men (n=26) aged ≥ 50 years participated in 16 weeks of high-intensity progressive resistance exercise training and bone-loading exercises and were randomly assigned to take ACET (1000 mg), ibuprofen (400 mg) or placebo 2 hours before each exercise session.

The primary outcome was the change in total body fat-free mass measured by dual-energy X-ray absorptiometry (DXA) at baseline and week 16. Our primary interest was in the comparison of the acetaminophen and placebo groups.