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     Juerg Senior Member Username: Juerg Post Number: 1527 Registered: 04-2006 |
here is an interesting article, which supports our new findings in humans as well. The cardiac output has a direct effect on lactate turn over in humans as well. Here first the abstract : Lactate kinetics in exercising Thoroughbred horses: regulation of turnover rate in plasma J. M. Weber, W. S. Parkhouse, G. P. Dobson, J. C. Harman, D. H. Snow and P. W. Hochachka Physiology Unit, Animal Health Trust, Newmarket, Suffolk, United Kingdom. Plasma lactate turnover rate of Thoroughbred racehorses was measured by bolus injection of [U-14C]lactate at rest and two levels of sub maximal treadmill exercise (3-4 m/s trot, 6% incline, and 6.5 m/s horizontal canter). Our goals were 1) to determine the relative effects of changes in cardiac output and in plasma lactate concentration on turnover rate [using cardiac output data from Weber et al. (28)] and 2) to assess the importance of lactate as a metabolic fuel in a trained animal athlete. Lactate turnover rates were 9.3 mumol.min-1.kg-1 (rest), 75.9 mumol.min-1.kg-1 at the beginning of the trot protocol [45% maximum O2 uptake (VO2max)], 50.3 mumol.min-1.kg-1 later in the same protocol (50% VO2max), and 66.1 mumol.min-1.kg-1 during the canter protocol (55% VO2max). Both changes in cardiac output and in plasma lactate concentration had a significant effect on turnover rate. Variation in plasma lactate fluxes of Thoroughbreds during exercise follows the standard mammalian pattern, but this substrate only plays a minor role as an oxidizable fuel in horses. The oxidation of plasma lactate accounts for less than 5% of metabolic rate (VO2) during submaximal work. Adjustments in cardiac output and in metabolite concentration represent, respectively, the coarse and fine controls for the regulation of plasma metabolite turnover rate Now in humans we see that in the second part of a FaCT CLR test the lactate turn over ( use of lactate as an energy source ) seem to be directly influenced by the cardiac hemodynamic. Meaning : If the CCT is or stays above 30 sec the lactate turn over is very slow. As soon the CCT drops below 30 seconds the lactate turn over is increased dramatically. The CO ( cardiac output can go in 2 directions. It remains high due to a high EDV / SV but a drop in HR or the opposite. A still very high HR ( slow HR recovery, but a drop in EDV/SV. Now the discussion here will remain: In horses maximal HR does not change : ( Leonnie) , so the CO will be not changing either as CO is HR x SV. If maximal HR does not change so does SV not change dramatically , as SV is dependent on EDV and EF %. If EDV structurally increases so will max. HR change due to the connection between LVET and heart size. So here is an interesting potential difference between the human and other animals heart to a heart of horses. @ possibility : 1. The horses really react physiologically different than any other animal. 2. The believe in max HR not changing is a myth in horse trainers and earlier or later will change , as soon we can test more efficient EDV and SV in horses as well. Cheers Juerg | ||
| Juerg Senior Member Username: Juerg Post Number: 1529 Registered: 04-2006 |
Here is an interesting article I got sent as a part of the discussion we have on the Human Forum under FaCT testing and lactate recovery. Here to read and follow if you are interested the discussion on teh FaCT thread. The Japan Racing Association (JRA) established the first international race, "The Japan Cup" in 1981. (The race has formally awarded international Group 1 status by the International Cataloguing Standards Committee in 1992 and now has carried out somewhere around the end of November as the 13th race of the World Series Racing Championship). At the time the difference of racing performance was clear between the Japanese and Euro-American horses. However, the Japanese breeders and personnels of race have continued their efforts to obtain good stallions and mares from abroad and to improve their procedures for handling and training racehorses. At last in 1998, Seeking the Pearl won the overseas group 1 race (Fr, Prix Maurice de Gheest) for the first time as the Japanese racehorse. After this event Japanese racehorses continuously took an active part in overseas races. For instance, Taiki Shuttle (1998, Fr, Prix Jacques le Marois), Agnes World (1999, Fr, Prix de l'Abbaye de Longchamp, 2000,U.K , Darley July Cup), El Condor Pasa (1999, Fr, Grand Prix de Saint-Cloud, 2nd -Prix de l'Arc de Triomphe), Stay Gold (2001, IRE, the Dubai Sheema Classic). These results clearly prove that Japanese racehorses have been improved in quality. It was T.M. Opera O (JPN, 19 96, Opera House/Once Wed) who played an important role in rece nt Japanese racing. He retired at December 2001. Career Wins/Starts is 14/26. He won 7 Japanese G1 races (1.25-2miles, including the Jap an Cup in 2000: defeating Fan tastic Light and Montjeu.) The number of these champion ships is a Japanese record. It is a noteworthy number con sidering advancement of all Japanese racehorses. T.M. Opera O triumphed at 2000 Arima Kinen (Grand Prix) We attempted to evaluate the performance potential of T.M. Opera O with exercise physiology. There have been many reports that the performance potential of racehorses was evaluated. How- ever, there is no report of the top-level racehorse. To clarify the performance potential of such a racehorse offers the key to understand the nature of prowess. In addition it will become a valuable index to evaluate the performance potential of other horses with exercise physiology. In this article, the exercise physiological findings of T.M. Opera O for ten months from March 2001 are presented. Also we would like to prove a part of his prowess. There are various factors affecting the racing performance, which are cardiac, respiratory and muscle function, physical constitution, biomechanics, etc. Firstly, we monitored the heart rate using the electrocardiogram at rest (Holter-type Electrocardiograph, Japan)1 and exercise (Acculex, Finland)2. Secondly, we measured the blood lactate after exercise using the lactate analyzer (YSI 1500 SPORT, Japan)3, because it is produced by anaerobic and submaximal exercise and so the aerobic exercise ability can be estimated from it. Finally, we carried out the echocardiography (EUB-6000, 2~4MHz, Japan)4 at rest to examine the cardiac function. The heart rate at rest was 25 beat per minute. Those of racehorses have been reported as 26-50beat per minute (Fregin, 1982). It has been thought that the heart rate at rest varies with degree of stimu- lation with automatic nerve: sympathetic and parasympathetic nerve (Hamlin et al., 1972). It is reasonable to suppose that the heart rate of racehorse trained well is low with a highly active parasympathetic nerve as same as human athlete. It is inferred from this that the heart rate of T.M. Opera O is low with a highly active parasympathetic nerve. Next, we present his heart rate and blood lactate change after exerc ise compared with other racehorses. We measured the heart rate and blood lactate at work-out, and we compared the average of T.M. Opera O (total five measurement) with the average of ten other racehorses (one measurement). We selected ten racehorses at random from various classes (from maiden horse to winner of group race). We monitored heart rate every five seconds using heart rate meter. There has been a report that recovery heart rates at 5 minutes after exercise were correlated with fastest winning time in standardbred horses (Marsland WP, 1968), so we used this index. Blood lactates were compared using the venous blood collected at 10 minutes after exercise. Equipped holter type Electrocardiograph with blanket The heart rate of T.M. Opera O at 5 minutes after exercise was lower than those of other ten horses. The average heart rate (112.4 beat per minute) of T.M. Opera O differed significantly in comparison with that (128.5 bpm) of other ten horses (Welch's t-test p<0.05). There was no difference in their maximal heart rates at exercise. The result clearly shows that the heart rate recovery of T.M. Opera O is more rapid than other horses after exercise. The average blood lactate (16.49mmol/L) of T.M. Opera O differed significantly in comparison with that (20.54mmol/L) of other ten horses (Welch's t-testAp<0.05). The blood lactate is influ- enced by exercise intensity. However, because all exercise was done at almost same level (maximal or submaximal exercise) in this trial, the difference between the two clearly shows that T.M. Opera O could afford to supply much aerobic energy without using anaerobic energy in comparison with other ten horses. There has been a report that the majority of the energy (90 percent) was supplied aerobica- lly during a race of 2400 m (Eaton.M.D., 1994). Therefore, it is considered that T.M. Opera O with better aerobic exercise ability could run with advantage. Finally, we make observations about echocardiography of T.M. Opera O. Creating an ultrasound image of the left ventricular outflow tract, a stroke volume of heart was calculated on the follow- ing formula. SV=VTIX(AoD/2)2X3.14 (SV: stroke volume, VTI: velocity time integral, AoD: aorta diameter) There has been a report that stroke volumes in the resting thoroughbreds were 593-1164ml, or 1.2-2.6ml/kg (Eberly et al., 1964). The stroke volume of T.M. Opera O was 1448ml, or 2.98ml/kg. His stroke volume largely surpassed values of the report. It is possible that we had a margin of error because of noninvasive test using echocardiography. However, even though we took this into consideration, his volume was still high. We also can say that T.M. Opera O had good oxygen-carrying capacity of the blood due to his high stroke volume. Consequently, it is clear that T.M. Opera O had an advantage over other horses when they ran. After exercise, blood was taken from him to measure blood lactate We examined a wall thickening of left ventricle supplying all parts of the body with blood. There has been a report that left ventricular walls at end-diastole and end-systole were 2.0`2.9cm and 3.2 `4.5cm (Reef, et al., 1991). That of T.M. Opera O was 3.56cm and 4.95cm. This data supports the capacious stroke volume of T.M. Opera O. It is inferred from this data that extraordinary cardiac output of T.M. Opera O produced by strong force of the heart's contractions. We performed some exercise physiological tests of T.M. Opera O to analyze his performance potential in this study. As a result, his prowess was confirmed not only by his racing performance but also by scientific basis. It is clear that the data gained from this study become a very useful index when we evaluate performance potential of other horses for the future. However, we analyzed only some factors to measure performance potentials in spite of the fact that performance of a racehorse was affected by a number of factors. We must continue considering the methods of ability rating for racehorses including new methods. |