摘要:

SummaryThe objectives of this study were to determine the effect of 1) dexamethasone (DEX) on serum osteocalcin concentration (OC) in untrained and trained horses and 2) DEX, administered weekly, on serum OC and metacarpal bone mineral content in horses during training. Inexperiment 1, the baseline concentrations of OC and endogenous Cortisol (COR) were determined every 2 h during a 24 h period. Inexperiment 2, DEX (0.2 mg/kg bwt i.v.) was administered before and after 6 weeks of exercise training. Inexperiment 3, horses received either 0.2 mg/kg bwt i.v. DEX (n=5) or saline (n=5) i.v. on a weekly basis for 8 weeks, with the horses exercising 5 times per week. Metacarpal mineral content was measured weekly on each forelimb by photon absorptiometry. Inexperiment 1, serum COR concentration fluctuated between mean (± s.e.) 82 ± 4 (0800 h) and 22 ± 2 (2000 h) ng/ml, but significant variations in serum OC were not detected. Inexperiment 2, serum OC was decreased between 6 and 36 h after DEX treatment both pre‐ and post training. Inexperiment 3, serum OC was not different at any sampling time during any 7 day period after saline administration. In contrast, each week after DEX, serum OC was decreased between 6 and 48 h. However, differences in serum OC (P=0.055) and bone mineral content (P=0.055) between treatment and control groups were not detected over the 8‐week period. It was concluded that dexamethasone administered weekly to horses in exercise training altered the pattern of serum osteocalcin, but there was no change in metacarpal bone mineral c

ISSN:0425-1644    

DOI:10.1111/j.2042-3306.1995.tb04971.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryAcclimation to treadmill exercise and to a respiratory gas collection mask were studied in 3 groups of Thoroughbred or Standardbred horses. Heart rate and plasma lactate concentration were measured at rest and at the completion of each speed increment during a series of acclimating runs at 4, 6 and 8 m/s on a treadmill inclined at a 10% slope. No significant differences were found in the heart rate at 4, 6 or 8 m/s between acclimating runs for any of the groups, except for a reduction between runs 1 and 2 at 4 m/s in a group of 19 racehorses that received 2 acclimating runs (Group 1). Heart rate values at 4 and 6 m/s were significantly higher during the subsequent exercise test in a group of 12 racehorses that received 4 prior acclimating runs (Group 3). Plasma lactate concentration was significantly reduced at 4 and 6 m/s from run 1 to 2 inGroup 1and at all speeds in a group of 6 experimental horses (Group 2) between run 1 and subsequent runs. There was also a significant reduction in plasma lactate concentrations at 6 and 8 m/s between runs 2 and 4 inGroup 2and between runs 3 and 4 at 8 m/s. A temperament scoring system was used to describe the behaviour of the horse on the treadmill. With the exception of 1 horse, the temperament score improved significantly, indicating acclimation to the treadmill after the first acclimating run inGroups 2and3.We conclude that acclimation occurred in the majority of horses after 1 or 2 exposures to treadmill exercise and a gas collection mask. However, there was substantial variability between horses and care must be taken when interpreting submaximal heart rate and plasma lactate data. This has important implications for the use of common measurements of exercise capacity such as V200and VLA4, which rely on values obtained during submaximal exercise.

ISSN:0425-1644    

DOI:10.1111/j.2042-3306.1995.tb04972.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryThe aim of this study was to document the 24 h urinary Cortisol concentrations during a rest day and a day that included prolonged exercise. The influence of exercise on disposition (plasma, urine) of a dose of Cortisol (1 mg/kg) was also assessed. Six adult saddle horses were used. In one experiment, urinary Cortisol elimination rates were measured during rest and prolonged exercise (56 km, 12 km/h) corresponding to about 50% of the V̇O2max. In another experiment, horses received, according to a crossover design, an intravenous (i.v.) bolus administration of Cortisol (1 mg/kg) either at rest or during the same prolonged exercise.The urine Cortisol concentration was lower than 100 ng/ml in the control resting horse. It was increased by exercise but the maximal concentration was lower than 300 ng/ml and returned to control values by 10 h after the end of exercise. After 1 mg/kg Cortisol i.v. Cortisol clearance was decreased by exercise (552 ± 143 vs. 452 ± 59 ml/kg/h, mean ± s.d.), but the difference was not significant The peaks of urinary Cortisol ranged from 760 to 21,967 ng/ml and occurred 0.8 to 6.9 h after Cortisol administration depending on the time of the first urination after administration. The return to values below 100 ng/ml was observed after 21 h in all horses. The 1000 ng/ml threshold for Cortisol control in urine after i.v. Cortisol (1 mg/kg) is specific (conservative) but of low sensitiv

ISSN:0425-1644    

DOI:10.1111/j.2042-3306.1995.tb04973.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryThe exercise intensity of horses competing in the cross country phase of an advanced horse trial (Group 1; n=17) and an advanced 3‐day combined training event (Group 2; n=7) over a similar course on the same day was investigated. Environmental conditions during the trial were cool. Heart rates were continuously recorded at 5 s intervals by a heart rate monitor. Mean ± s.d. heart rates forGroup 1andGroup 2were 167.7 ± 24.0 beats/min and 171.4 ± 19.2 beats/min, respectively, (P>0.05). Plasma lactate concentrations were determined at rest, within 60 s post exercise and 10 min post exercise. Mean lactate concentrations were highest immediately post exercise (Group 1=15.18 ± 5.79 mmol/l;Group 2=19.10 ± 4.22 mmol/l) and had declined significantly in 10 min (Group 1=11.15 ± 6.56 mmol/l;Group 2=16.06 ± 6.11 mmol/l). Lactate concentrations were not significantly different between groups at each time period. We concluded that the work effort for the cross country phase was not different between advanced horse trial and 3‐day competitions for horses competing under similar conditions during non stressful environmental

ISSN:0425-1644    

DOI:10.1111/j.2042-3306.1995.tb04974.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

ISSN:0425-1644    

DOI:10.1111/j.2042-3306.1995.tb04975.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

ISSN:0425-1644    

DOI:10.1111/j.2042-3306.1995.tb04976.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

ISSN:0425-1644    

DOI:10.1111/j.2042-3306.1995.tb04977.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

ISSN:0425-1644    

DOI:10.1111/j.2042-3306.1995.tb04978.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

ISSN:0425-1644    

DOI:10.1111/j.2042-3306.1995.tb04979.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

ISSN:0425-1644    

DOI:10.1111/j.2042-3306.1995.tb04980.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY