PMID- 17402423
OWN - NLM
STAT- MEDLINE
DCOM- 20070502
LR  - 20131121
IP  - 36
DP  - 2006 Aug
TI  - Effects of short-term training on insulin sensitivity and skeletal muscle glucose 
      metabolism in standardbred horses.
PG  - 226-32
AB  - REASONS FOR PERFORMING STUDY: Increased insulin sensitivity occurs after a period 
      of exercise training, but the mechanisms underlying this training-associated 
      increase in insulin action have not been investigated. OBJECTIVE: To examine the 
      effects of short-term endurance training (7 consecutive days) and a subsequent 
      period of inactivity (5 days) on whole body insulin sensitivity and GLUT-4 
      protein and the activities of glycogen synthase (GS) and hexokinase (HK) in 
      skeletal muscle. It was hypothesised that training would increase insulin 
      sensitivity in association with increased GLUT-4 protein and activities of GS and 
      HK, but that these changes would be transient, returning to baseline after 5 days 
      of inactivity. METHODS: Seven mature Standardbred horses completed training 
      consisting of 7 consecutive days of 45 min of treadmill exercise at a speed that 
      elicited 55% of pretraining maximal aerobic capacity (VO2peak). Insulin 
      sensitivity was determined by rate of glucose disposal (M) during the last 60 min 
      of a 120 min euglycaemic-hyperinsulinaemic clamp (EHC) performed before (-2 days) 
      and at 1 and 6 days following training. VO2peak was measured before (UT) and 
      after (TR) training and the period of inactivity (IA). RESULTS: Training resulted 
      in a 9% increase in mean VO2peak (P<0.05) that was maintained following 
      inactivity (IA). Mean M values were more than 2-fold higher (P<0.05) in TR than 
      in UT. Mean M was also higher (P<0.05) in IA when compared to UT. GLUT-4 protien 
      abundancewas more than 10-fold higher in TR and IA (P<0.001) than in UT. Pre-EHC 
      GS activity and GS fractional velocity were increased (P<0.05) in TR when 
      compared to UT and IA. Pre-EHC HK activity was increased (P<0.05) in IA when 
      compared to UT and TR. Muscle glycogen was 66% lower (P<0.05) in TR than in UT 
      and IA. CONCLUSIONS: Short-term training resulted in increases in whole body 
      insulin sensitivity, and GLUT-4 protein content and glycogen synthase activity in 
      skeletal muscle. The enhancements in insulin sensitivity, GLUT-4 protein and 
      glycogen synthase activity were still evident after 5 days of inactivity. 
      POTENTIAL RELEVANCE: Insulin resistance in equids has been associated with 
      obesity and predisposition to laminitis. Regular physical activity may mitigate 
      risk of these conditions via enhancement of insulin sensitivity and/or control of 
      bodyweight.
FAU - Stewart-Hunt, L
AU  - Stewart-Hunt L
AD  - Department of Biomedical Science and Pathobiologyt, University of Guelph, Guelph, 
      Ontario NIG 2W1, Canada.
FAU - Geor, R J
AU  - Geor RJ
FAU - McCutcheon, L J
AU  - McCutcheon LJ
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - Equine Vet J Suppl
JT  - Equine veterinary journal. Supplement
JID - 9614088
RN  - 0 (Glucose Transporter Type 4)
RN  - 0 (Insulin)
RN  - EC 2.4.1.11 (Glycogen Synthase)
RN  - EC 2.7.1.1 (Hexokinase)
RN  - IY9XDZ35W2 (Glucose)
SB  - IM
MH  - Animals
MH  - Area Under Curve
MH  - Female
MH  - Glucose/*metabolism
MH  - Glucose Clamp Technique/veterinary
MH  - Glucose Transporter Type 4/metabolism
MH  - Glycogen Synthase/metabolism
MH  - Hexokinase/metabolism
MH  - Horses/blood/metabolism/*physiology
MH  - Insulin/*metabolism
MH  - Male
MH  - Muscle, Skeletal/*metabolism
MH  - Oxygen Consumption/physiology
MH  - Physical Conditioning, Animal/*physiology
MH  - Time Factors
EDAT- 2007/04/04 09:00
MHDA- 2007/05/03 09:00
CRDT- 2007/04/04 09:00
PHST- 2007/04/04 09:00 [pubmed]
PHST- 2007/05/03 09:00 [medline]
PHST- 2007/04/04 09:00 [entrez]
AID - 10.1111/j.2042-3306.2006.tb05544.x [doi]
PST - ppublish
SO  - Equine Vet J Suppl. 2006 Aug;(36):226-32. doi: 
      10.1111/j.2042-3306.2006.tb05544.x.