title: Assessment of alterations in triglyceride and glycogen concentrations in muscle tissue of Alaskan sled dogs during repetitive prolonged exercise.
abstract: OBJECTIVE
  To assess changes in muscle glycogen (MG) and triglyceride (MT) concentrations in aerobically conditioned sled dogs during prolonged exercise.
  
  
  METHODS
  54 Alaskan sled dogs fed a high-fat diet.
  
  
  METHODS
  48 dogs ran 140-km distances on 4 consecutive days (cumulative distance, up to 560 km); 6 dogs remained as nonexercising control animals. Muscle biopsies were performed immediately after running 140, 420, or 560 km (6 dogs each) and subsequently after feeding and 7 hours of rest. Single muscle biopsies were performed during recovery at 28 hours in 7 dogs that completed 560 km and at 50 and 98 hours in 7 and 6 dogs that completed 510 km, respectively. Tissue samples were analyzed for MG and MT concentrations.
  
  
  RESULTS
  In control dogs, mean +/- SD MG and MT concentrations were 375 +/- 37 mmol/kg of dry weight (kgDW) and 25.9 +/- 10.3 mmol/kgDW, respectively. Compared with control values, MG concentration was lower after dogs completed 140 and 420 km (137 +/- 36 mmol/kgDW and 203 +/- 30 mmol/kgDW, respectively); MT concentration was lower after dogs completed 140, 420, and 560 km (7.4 +/- 5.4 mmol/kgDW; 9.6 +/- 6.9 mmol/kgDW, and 6.3 +/- 4.9 mmol/kgDW, respectively). Depletion rates during the first run exceeded rates during the final run. Replenishment rates during recovery periods were not different, regardless of distance; only MG concentration at 50 hours was significantly greater than the control value.
  
  
  CONCLUSIONS
  Concentration of MG progressively increased in sled dogs undergoing prolonged exercise as a result of attenuated depletion.
authors.affiliation: Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK 74078, USA.
authors.forename: Erica C
authors.initials: EC
authors.lastname: McKenzie
authors.forename: Kenneth W
authors.initials: KW
authors.lastname: Hinchcliff
authors.forename: Stephanie J
authors.initials: SJ
authors.lastname: Valberg
authors.forename: Katherine K
authors.initials: KK
authors.lastname: Williamson
authors.forename: Mark E
authors.initials: ME
authors.lastname: Payton
authors.forename: Michael S
authors.initials: MS
authors.lastname: Davis
mesh_terms: D000818:Animals; D004285:Dogs; D006003:Glycogen / Q000378:metabolism*; D007700:Kinetics; D018482:Muscle, Skeletal / Q000378:metabolism*; D010805:Physical Conditioning, Animal; D005082:Physical Exertion / Q000502:physiology*; D012420:Running / Q000502:physiology; D014280:Triglycerides / Q000378:metabolism*
chemical_list: D014280:Triglycerides; D006003:Glycogen