title: Skeletal muscle damage in the rat hindlimb following single or repeated daily bouts of downhill exercise.
abstract: This study was conducted to quantify and compare the extent of fibre degenerative and regenerative processes in different muscles of the rat hindlimb following single or repeated daily bouts of treadmill exercise. Wistar rats were used as non-exercised controls, or subjected to one, five, or ten (n = 8 per group), 30-minute daily bouts (-16 degrees, 12-15m.min-1) of downhill exercise. Soleus (S), vastus lateralis (VL), medial gastrocnemius (MG), plantaris (P), and tibialis anterior (TA) muscles were analyzed from transverse cryosections stained with either H&E for morphological alterations indicative of fibre degeneration or regeneration, or mATPase activity for determination of fibre type. Results showed that in all groups, the percentage of morphologically altered fibres (%AF) was greater in S (4-8%) than in MG, VL, P, or TA (1-2%). The %AF across all muscles was greater following only one, versus multiple exercise bouts, or versus no exercise. The proportions of AF of different histochemical types followed the same distribution as the fibre type in the muscle area examined. These direct assessments indicate that the extent of fibre degenerative and regenerative processes varies among the different muscles involved, and is greater following a single bout, compared to repeated daily bouts of exercise.
authors.affiliation: School of Physical and Health Education, University of Toronto, Canada.
authors.forename: H K
authors.initials: HK
authors.lastname: Smith
authors.forename: M J
authors.initials: MJ
authors.lastname: Plyley
authors.forename: C D
authors.initials: CD
authors.lastname: Rodgers
authors.forename: N H
authors.initials: NH
authors.lastname: McKee
mesh_terms: D000251:Adenosine Triphosphatases / Q000032:analysis; D000818:Animals; D004396:Coloring Agents; D015925:Cryopreservation; D003593:Cytoplasm / Q000648:ultrastructure; D004801:Eosine Yellowish-(YS); D005260:Female; D005456:Fluorescent Dyes; D006416:Hematoxylin; D006614:Hindlimb; D008867:Microtomy; D018485:Muscle Fibers, Skeletal / Q000145:classification / Q000201:enzymology / Q000648:ultrastructure; D018482:Muscle, Skeletal / Q000201:enzymology / Q000473:pathology* / Q000648:ultrastructure; D009929:Organ Size; D051381:Rats; D017208:Rats, Wistar; D012038:Regeneration; D012420:Running / Q000502:physiology*
chemical_list: D004396:Coloring Agents; D005456:Fluorescent Dyes; D000251:Adenosine Triphosphatases; D004801:Eosine Yellowish-(YS); D006416:Hematoxylin