| Author | Message | ||
     Robh Senior Member Username: Robh Post Number: 393 Registered: 12-2007 |
Posted on the Google Wattage list :- "I'd like your opinion about this test, if you use it as control test for your athletes, if you find this usefull or it's still better to use others submaximal test. If so, which one(s) you still prefer? In this link there's the Basso slopes www.mapeisport.it/public/IvanBasso/endur ance.pdf And this is the protocol and equation used: PREDICTION OF TIME TO EXHAUSTION FROM BLOOD LACTATE RESPONSE DURING SUBMAXIMAL EXERCISE IN COMPETITIVE CYCLISTS. Sassi A, Marcora SM, Rampinini E, Mognoni P, Impellizzeri FM The aim of this investigation was to develop and validate a new method to predict time to exhaustion (pTE) from blood lactate variables measured during a submaximal non-exhaustive constant workload cycling test in professional cyclists. A multiple regression equation to estimate pTE from blood lactate variables measured within the first 10 min of a submaximal test and TE was determined in 40 competitive cyclists. Predicted TE reliability [individual coefficient of variation (CV)] was calculated in eight amateur cyclists who repeated the proposed test three times. Seasonal variations of pTE were monitored in 12 professional cyclists. Validity of pTE was determined by the known-group difference method in 49 professional cyclists. The prediction equation was: log(n)TE = 4.2067 - 0.8221(log(n) B) - 0.2519 (log(n) C), where B is the lactate concentration at the 10th minute of the constant workload test and C is the lactate slope calculated between the 5th and 10th minute (adjusted r (2) =0.83, root mean square error in cross validation=23.1%). Predicted TE CV was 11.7%. The pTE obtained at the beginning of the season and the best and worst tests performed during the competitive season, resulted 162, 224 and 103% higher than the basic period test, respectively (P<0.05). Predicted TE was the only parameter discriminating elite from subelite professional cyclists. In conclusion, this study demonstrates that pTE is a valid and practical alternative to incremental tests and direct measures of endurance capacity requiring exhaustive efforts for the evaluation of competitive cyclists. Eur J Appl Physiol. 2006 May;97(2):174-80. | ||
| Juerg Senior Member Username: Juerg Post Number: 1130 Registered: 04-2006 |
Hey Rob. Thanks for this info. It looks very interesting and I have to do some more indepth reading to completely get a proper understanding on it. At a first glance it is a very smart way to actually try to get this result. If we look it from a very different angle, meaning from an energy point of view and from the view we look at lactate . Lactate as not being the source of fatigue , but being the source of energy. Here some thoughts. In the above study it seems, that they use lactate as a way of calculating Fatigue". So they use the values of lactate as a sign , that if the values where higher, than the athlete may "fatigue" earlier. Now here the problem. If they would have given glucose or direct lactate to the test person, the lactate values would have been even higher , but the duration of "fatigue" would have been drawn further out. In that case, their conclusion would have been very hard to explain. Now the way they made their conclusion, was without additional feeding. This leads to the unfortunate conclusion by many readers, that the level of lactate had a direct influence of the "fatigue". When in fact it is exactly the opposite. Explanation why I think in that direction. If you go from our point of view, that lactate is a very efficient energy source, than you will come to the conclusion, that as higher the lactate, the more energy is used.( oxygen independent) So there is a limitation ( without feeding ) on lactate metabolisme ( production ) as it is limited to oxygen independent and O2 dependent metabolisme. So athletes , who had a higher lactate level used up the available energy faster, than the athletes with potentially lower level . ( Given the possibility , that their muscel fiber ratios where similar and that the energy storage ability was similar as well ). So when using lactate the so called ESC ( energy system capacity (= total energy that can be produced ) was different than the once with the lower lactate. The guys with the lower lactate have a better EPS ( energy power system ) = total energy per time unit used. So here my theoretical thoughts : If they had a higher lactate level , than they were more in the ESC system compared with the one , who where lower in lactate , and this guys where more in the EPS system. To make it more in numbers: ATP and CP energy productions are very extreme ESC ATP produces 72kcal/min +- for a time of 9 - 10 sec Lactate is somewhat better and more towards the EPS with 36 kcal/min for about 1 min 20 sec. In comparison to Oxygen dependent energy production which is somewhere of 7.2 - 19.1 kcal / min but for a duration of 2 h 20 and longer. So this would give a physiological explanation , versus the above mathematical complicated calculation. End result may be the same. When we see higher lactate values we shift more from the EPS system or for us easier the Oxygen dependent system , to the ESC of or us the oxygen independent system, where you use lactate as one of the better energy substrate, but with a much shorter time frame , before you run out of this ability.( time to exhaustion ) So the test is a very interesting part and it is absolutely possible to get some very nice help out of it . It is as so often a question of how many time you use a test and as better and closer you think in a specific idea, as more you can use it to "predict" certain outcomes either as a calculation or as information gathered by the biomarkers. Summary : As lactate is used as an energy source, but with limited supply in a certain intensity the values can possibly be used to predict upcoming exhaustion. I think the idea in the above study is based on lactate as a potential reason of "fatigue" and by interferring during the test with nutritional intervention the study would have potentially given no result. Due to the fact of no interference, the result is the same as lactate level will be higher and the energy delivery system therefor earlier exhausted ( more oxygen independent trend ). Last but not least : The extreme drop of 20 % performance information by Basso seems to me very high from off season the race season. This would mean in a 10 km runner, who can run 30 min a 36 min run is his limit. That would be considered, that something is teribly wrong . A maraton runner with a time of 3 hours only can run 3 h 36 min after 1 - 3 month not sick but less training. We never ever see in our top athletes this incredible change . This unfortunately leads to the "bad" idea, whether the drop , respectively the incredible "improvement" during the race season is based on real physiological changes or rather based on some ( after that season proven )physiochemical intervention ? When we look , that VO2 is the product of CO ( cardiac output )and (A-V) o2 difference. and CO is a structural situation which not will change that strong.( exception of a disease or complete bed rest ) The pulmonary system is build on a structural change as well and will not change in the off season at all ( maintenace work ) , than we may loose some of the systems responsible for A- V O2 difference, which is plasma volume and a bit Hb levels, but with a healthy food intake the Hb in fact may actually increase, rather than drop. The potential increase is maximal allowed to a level of 50 Hct. The regular Hct testing we see, shows a very small change in Hct on our athletes and the only change in performance is the workouts , where they push the CGM to a bit of a higher level. 20 % is a lot , as this would be in a 60 min TT 12 min and we never see this difference with the exception of a sickness over a longer time period. If you look closely you can see, that this incredible better performance in the test from Basso was achieved as longer the time, but in the high end you see a very small difference between the performance , than you have to ask: Intramuscular coordination is lost relatively fast during rest period. , Enzymatic reactions are lost relatively fast, so why do we see in that area a relative small drop, as we have to assume that during a rest period the athlets will do less high end workouts, but may enjoy some longer relaxed rides with friends and family . In the above case we see a big drop exactly there, where we see very little loss ( as it is build over yeasr due to structural workouts ), and a big improvement , where we see very little improvement, ( as structural imporvement take time over years ) . Only an incredible gain of weight ( Ulrich ) may to a certain extend explain the watt / Kg ratio change, but even in Ulrich's case it seems that some physiochemical intervention in the improvement of the A-V O2 difference where to blame for the difference in winter and sommer performance. This thoughts should not interfer with the proposed methodes, but it would be nice to have that tested on athletes which have very little or no connection to some specific "training- interventions . " For the records: Te result we have in the original work from Conconi,in the development of the conconi test ,had as well the unfortunately situation , that many of the test people where running on the so called deflection point with some specific help , and as the test method was applied to normal users ( see study done by Chlebek, Smart , Sanders and Feldmann (defelctionpoint in comparison with real running speed during a Jasper -Banff relay )the so called anaerobic threshold was far off the actuall deflection point determent by the Conconi test. This was in the mean time done in many research projects all over the world. |