title: Acute loading and aging effects on myostatin pathway biomarkers in human skeletal muscle after three sequential bouts of resistance exercise.
abstract: To determine the influence of age and resistance exercise on myostatin pathway-related genes, younger (n = 10; 28 ± 5 years) and older (n = 10; 68 ± 6 years) men underwent four testing conditions (T1-T4). A baseline (T1) muscle sample was obtained, whereas the second and third biopsies were obtained 48 hours following the first and second training sessions (T2, T3), and a final biopsy was taken 24 hours following T3. The training sessions consisted of 3 sets of 10 repetitions (80% of one repetition maximum) on leg press, hack squat, and leg extension exercises. Follistatin (FST) messenger RNA was greater in older compared with younger men at T1 and T2 (p < .05). Follistatin-like 3 (FSTL3) messenger RNA was greater in older compared with younger men at T1 and T4 (p < .05). In older men, there was a significant decrease in myostatin (MSTN) messenger RNA at T4 (p < .05). Older men contained less active (Ser-425 phosphorylated) SMAD3 (p-SMAD3) protein than younger men at T3 and T4 (p < .05).Although it is well known that younger individuals possess a greater hypertrophic potential to resistance exercise, it appears that older individuals may paradoxically possess a more favorable resistance exercise response regarding myostatin pathway-related genes and a protein marker of pathway activity. Future research is warranted to examine the physiological significance of this age-dependent mechanism.
authors.affiliation: Department of Health and Exercise Science, University of Oklahoma, Norman, OK 73019-6081, USA.
authors.forename: Vincent J
authors.initials: VJ
authors.lastname: Dalbo
authors.forename: Michael D
authors.initials: MD
authors.lastname: Roberts
authors.forename: Kyle L
authors.initials: KL
authors.lastname: Sunderland
authors.forename: Chris N
authors.initials: CN
authors.lastname: Poole
authors.forename: Jeff R
authors.initials: JR
authors.lastname: Stout
authors.forename: Travis W
authors.initials: TW
authors.lastname: Beck
authors.forename: Mike
authors.initials: M
authors.lastname: Bemben
authors.forename: Chad M
authors.initials: CM
authors.lastname: Kerksick
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D015415:Biomarkers / Q000378:metabolism; D003199:Computer Systems; D004032:Diet; D015444:Exercise / Q000502:physiology*; D038681:Follistatin / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D015151:Immunoblotting; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology*; D055435:Myostatin / Q000378:metabolism*; D010766:Phosphorylation; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism; D055070:Resistance Training; D051900:Smad3 Protein / Q000378:metabolism; D013997:Time Factors; D055815:Young Adult
chemical_list: D015415:Biomarkers; D038681:Follistatin; D055435:Myostatin; D012333:RNA, Messenger; C497790:SMAD3 protein, human; D051900:Smad3 Protein