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Shelley Harper
Member
Username: Eventmad
Post Number: 8
Registered: 8-2005
| | Posted on Wednesday, Nov 1, 2006 - 5:19 am: |   |
Hi Dr O
Please can you help me. Please can you explain the value of measuring lactate in race / performance horses as a fitness indicator. Please could you also confirm when this should be run. My understanding of lactate is as follows: -
When there is no oxygen present the glucose is converted to lactate instead of energy. Therefore the measurement of lactate relates to anaerobic metabolism. However, I don't understand the value of measuring lactate. What exactly are you looking for ? Should you run lactate prior and immediately after exercise ?
Thanks Shelley ( United Kingdom ) |
Robert N. Oglesby DVM
Moderator
Username: Dro
Post Number: 16986
Registered: 1-1997
| | Posted on Wednesday, Nov 1, 2006 - 8:35 am: | |
Hello Shelly,
Though energy (2 ATP) is still derived as glucose is converted to lactate you are right the amount of accumulated lactate is proportional to the amount of anerobic metabolism. Aerobic energy production is more efficient but slower than anerobic system, which has to take over during even fairly short periods of maximal exercise. The more efficiently the horses muscles are working the more aerobic energy production that occurs prior to the take over and the lower the lactate production per unit of exercise.
From the paragraph above you might assume that the best racers might produce less lactate when racing but that is not always true because they do more work to win. This makes measuring lactate is a tricky thing and requires care and knowledge to interpret properly.
Lactate can be used to measure a change in fitness in the individual under controlled conditions. Under conditions of controlled, measured, submaximal exercise measuring blood lactate can be one indicator of fitness. For best results the exercise should be done in the exact same way each time and the blood taken at the same time, and the blood handled the same way. Obviously exactness is impossible so the results are only as good as how well you measure and control the exercise. As the results are charted over time they can be used as one factor to determine if the horse is still getting fitter as evidenced by a decreasing lactate level. When it flattens the horse may be about as fit under the current training regimen that he is going to get.
It is more difficult to compare lactate levels between horses to try and get an idea of competitiveness. I think the best supported technique is the velocity over a specified distance where the horse reaches a certain level of lactate in the blood. The faster the horse goes before reaching a certain level the more competitive he is thought to be:
Equine Vet J. 1997 Sep;29(5):365-9.
Estimation of performance potential of standardbred trotters from blood lactate concentrations measured in field conditions.
Courouce A, Chatard JC, Auvinet B.
Unite de Medecine du Sport Humaine et Equine Comparee (Pegase-Mayenne), Centre Hospitalier General, Laval, France.
The purpose of this study was to examine the relationship between V4 (velocity which results in a blood lactate concentration of 4 mmol/l), age and racing performance of Standardbred trotters and to establish V4 normal values to select good and poor performers. The specific influence of racing (RT) and training (T1 and T2) tracks was also examined. A total of 159 horses were divided into 5 age-groups from 2 to 6 and over and performed 330 standardised exercise tests of 3 steps performed at increasing speeds. The velocity of the horses was measured with a tachometer on the sulky. Blood lactate concentrations were measured from the jugular vein after each step. For the 5 age-groups, mean V4 values increased significantly (P < 0.05) with age between 2 and 4 years. After 5 years, this increase was reduced and became nonsignificant. The highest V4 values were obtained on the racing track (RT) and the lowest on the training tracks (T1; P < 0.05). No significant difference was found between RT and T2 nor between T1 and T2. Horses were defined as good performers (GP) when finishing between the first and the fifth place in a race or poor performers (PP) when finishing lower than fifth. V4 was significantly higher for GP than for PP (P < 0.05). Normal value of V4 were established for good and poor performers taking into account the 95% confidence interval of the data. Therefore, V4 depends on age and track and can be considered an important parameter to evaluate trotters' racing potential.
I am not aware of a well defined relation that can be used to judge fitness between the pre and post test levels but then again this may be something I am not aware of.
DrO |
