title: Age-dependent effects of treadmill exercise during a period of inactivity.
abstract: The objective of this study was to investigate the effect of a treadmill exercise protocol to prevent muscle weakness, atrophy and alterations in calcium regulation in adult, old and very old rats. Adult (7-12 months), old (29-30 months) and very old (34-36 months) F344BNF(1) rats were randomly assigned to weight bearing (WB), weight bearing exercise (WBX), non-weight bearing (NWB) and non-weight bearing exercise (NWBX) groups. The WB group was considered the sedentary-control animals. NWB rats were hindlimb unweighted for 14 days. WBX and NWBX groups were exercised on a treadmill for approximately 15 min four times daily. The contractile properties [diameter, peak active force (P(0)), specific tension (P(0)/CSA)] of single myosin heavy chain type II fibers and Ca regulation [Ca(2+) dependent ATPase activity] were determined. Fiber diameter reduced by 24% in the very old rats with NWB. P(0) and P(0)/CSA declined in the young adult and very old rats with NWB. NWBX attenuated these changes in the young and very old rats. Ca(2+) dependent ATPase activity increased with treadmill exercise during non-weight bearing in the young animals. In conclusion, the treadmill exercise is beneficial in attenuating the non-weight bearing-induced changes in the individual MHC type II muscle fibers of the gastrocnemius muscle.
authors.affiliation: Department of Physical Medicine & Rehabilitation, University of Minnesota, 420 Delaware Street SE, Minneapolis, MN 55455, USA.
authors.forename: P
authors.initials: P
authors.lastname: Arora
authors.affiliation: Department of Physical Medicine & Rehabilitation, University of Minnesota, 420 Delaware Street SE, Minneapolis, MN 55455, USA.
authors.forename: A D
authors.initials: AD
authors.lastname: Husom
authors.affiliation: Department of Ophthalmology, University of Minnesota, Minneapolis, MN, USA.
authors.forename: D A
authors.initials: DA
authors.lastname: Ferrington
authors.affiliation: Department of Physical Medicine & Rehabilitation, University of Minnesota, 420 Delaware Street SE, Minneapolis, MN 55455, USA.
authors.forename: L V
authors.initials: LV
authors.lastname: Thompson
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D007103:Immobilization / Q000502:physiology; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018656:Muscle Fibers, Fast-Twitch / Q000502:physiology; D018908:Muscle Weakness / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control; D009133:Muscular Atrophy / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control; D018995:Myosin Heavy Chains / Q000032:analysis; D005082:Physical Exertion / Q000502:physiology*; D020033:Protein Isoforms / Q000032:analysis; D051381:Rats; D011916:Rats, Inbred F344; D012519:Sarcoplasmic Reticulum / Q000201:enzymology; D016474:Weight-Bearing / Q000502:physiology
chemical_list: D020033:Protein Isoforms; D018995:Myosin Heavy Chains; D000252:Calcium-Transporting ATPases