title: N-acetyl-4-aminophenol and musculoskeletal adaptations to resistance exercise training.
abstract: N-acetyl-4-aminophenol (ACET) may impair musculoskeletal adaptations to progressive resistance exercise training (PRT) by inhibiting exercise-induced muscle protein synthesis and bone formation. To test the hypothesis that ACET would diminish training-induced increases in fat-free mass (FFM) and osteogenesis, untrained men (n = 26) aged ≥50 years participated in 16 weeks of high-intensity PRT and bone-loading exercises and were randomly assigned to take ACET (1,000 mg/day) or placebo (PLAC) 2 h before each exercise session. Total body FFM was measured by DXA at baseline and week 16. Serum bone-specific alkaline phosphatase (BAP) and C-terminal crosslinks of type-I collagen (CTX) were measured at baseline and week 16. Vastus lateralis muscle biopsies were performed at baseline and weeks 3 and 16 for prostanoid, anabolic, and catabolic gene expression by RT-PCR. In exercise-compliant men (ACET, n = 10; PLAC, n = 7), the increase in FFM was not different between groups (p = 0.91). The changes in serum BAP and CTX were not different between groups (p > 0.7). There were no significant changes in any of the target genes at week 3. After 16 weeks of PRT, the mRNA expressions of the anabolic marker p70S6K (p = 0.003) and catabolic marker muscle-atrophy F-box (MAFbx) (p = 0.03) were significantly reduced as compared to baseline in ACET. The mRNA expression of the prostanoids were unchanged (all p ≥ 0.40) in both groups. The administration of ACET (1,000 mg) prior to each exercise session did not impair PRT-induced increases in FFM or significantly alter bone formation markers in middle aged and older men.
authors.affiliation: College of Nursing, University of Colorado Anschutz Medical Campus, Mail Stop C288-19, 13120 East 19th Avenue, Aurora, CO 80045-2527, USA. catherine.jankowski@ucdenver.edu
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Jankowski
authors.forename: Wendolyn S
authors.initials: WS
authors.lastname: Gozansky
authors.forename: Paul S
authors.initials: PS
authors.lastname: MacLean
authors.forename: Benjamin
authors.initials: B
authors.lastname: Shulman
authors.forename: Pamela
authors.initials: P
authors.lastname: Wolfe
authors.forename: Robert S
authors.initials: RS
authors.lastname: Schwartz
authors.forename: Wendy M
authors.initials: WM
authors.lastname: Kohrt
mesh_terms: D000082:Acetaminophen / Q000494:pharmacology*; D000222:Adaptation, Physiological; D000469:Alkaline Phosphatase / Q000097:blood; D001842:Bone and Bones / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D016022:Case-Control Studies; D024042:Collagen Type I / Q000097:blood; D015444:Exercise; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D010012:Osteogenesis / Q000187:drug effects; D010455:Peptides / Q000097:blood; D055070:Resistance Training; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D024042:Collagen Type I; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D000082:Acetaminophen; D000469:Alkaline Phosphatase