Details of Lactate Testing by J. Olbrecht, Ph.D. (1999)


Published


Lactate tests are used to determine the conditioning profile of the swimmer with respect to his aerobic and anaerobic metabolic performance. Within the scope of the training process, the lactate tests are therefore a very important “link” to maximize the training efficiency.

 

For many years the interpretation and use of lactate in training was based on empirical assumptions lacking any scientific evidence about the real significance of blood lactate readings. As a consequence, coaches were faced with contradictory results, unrealistic interpretations and with inconsistent implementations in training. Success in competition was then rather a lucky strike than the result of a systematic, purposive and scientific founded procedure.

 

This article will present some new findings on basic lactate research which account for the misleading lactate interpretations and provide some new ways of working with lactate to minimize these misinterpretations and so increase the training efficiency.

 

Lactate pitfalls

There are two major factors that affect the significance  of blood lactate:

  1. the test procedure/protocol
  2. the metabolic processes leading to blood lactate

 

  1. the test procedure/protocol

Depending on the test protocol a swimmer may get different lactate values at a same swimming speed and consequently also different lactate curves. For example:

*the longer the effort, the higher the lactate concentration for the same speed

*a step test will provide lower lactate values than a one or two speed test with the same interval (swim distance) and at the same submaximal speed. For maximal or near to maximal intensities the lactate readings in the step test will be higher (fig. 1).

(step test—3 or more repetitions of the same interval distance or effort time with ca 1 minute rest between the repetitions. During each rest break one single blood sample is taken. one or two speed test—only 1 or 2 repetitions of the same interval distance. The rest break between the 2 repetitions lasts at least 15 min. during which several blood samples are taken to determine the highest lactate concentration.)

 

These differences in lactate values are not related to the conditioning of the swimmer but are due to a different test protocol. Moreover:

*lactate tests in the morning or in the evening provide also

different readings for the same effort. Indeed, an exercise in the afternoon produces on average 1 mmol/l lactate less than the same effort in the morning

*a very extensive and long workout or a few sprints before a lactate test exert a statistically significant influence (resp. lower and higher lactate concentrations for the same speed) on the lactate readings (fig. 2)

*muscle strength training within 24 hours before the lactate test results in higher values after a submaximal workout and lower concentrations after an all-out effort.

 

It is thus very important to plan the lactate tests taking into account the above mentioned interactions.

 

  1. the metabolic processes leading to blood lactate

The external factors of influence, as described above, can easily be controlled in order not to disturb the interpretation of the blood lactate values. But, much more difficult is to get the right insight in the origin of a blood lactate concentration. Over the last 5 years basic research corroborated that lactate is a very complex parameter mainly affected by the athlete’s oxygen uptake, lactate production and elimination. Depending on the characteristics of the effort, these 3 metabolic sub processes will be activated differently. The same lactate concentrations measured after different types of efforts are thus the result of a different participation of the 3 metabolic processes and will consequently enclose a different message. We therefore tried to trace back a lactate concentration to the valuation of the determining “drivers” and found that the origin of most lactate values could be described as a function of the maximal oxygen uptake )=the aerobic capacity) and the maximal glycolytic rate (=the anaerobic capacity) also called the maximal lactate production rate; lactate here rather refers to pyruvate than to lactate accumulating in the muscle which may lead to some confusion, but, from a metabolic point of view there is no real problems since the concentration ration of lactate and pyruvate in the whole process is 1:1.

 

Figure 3 presents a schematic overview of the metabolic energy supply in athletes. The aerobic capacity is determined by the rate of “combusting pyruvate,” linked with the consumption of oxygen. The higher the swimmer’s oxygen uptake per minute, the more pyruvate (via acethyl-CoA) will be broken down to water (H20) and carbon dioxide (CO2), the more energy per minute will be provided by the aerobic system and the faster the swimmer will be able to swim “aerobically.”

 

The glycolysis (part of the anaerobic system) needs to deliver enough pyruvate to be used by the aerobic system. If not enough pyruvate is supplied, the organism will try to find another acethyl-CoA provider such as the lipolysis (fat combustion). This may be the case in very well endurance (aerobic) trained athletes but is quite unusual for less endurance trained swimmers. If on the other hand, too much pyruvate is provided by the glycolysis (too much = more than can be assimilated by the oxygen system), the surplus pyruvate is converted to muscle lactate. But, if this happens in high quantities, the pH will decrease in the muscle and the arisen acidosis will inhibit further rate of glycolysis activity (slow down). Muscle lactate may afterwards be converted back to pyruvate as the aerobic system screws up the consumption of pyruvate (this means that also the oxygen uptake increases) or move to the blood circuit and enter the muscle elsewhere to be combusted (via conversion to pyruvate) there by the aerobic metabolic process.

 

The glycolysis itself also produces energy. The amount per glycogen molecule is very small, but since the glycolysis reacts very fast and starts simultaneously in a great number of muscle fibers a considerable high amount of energy can be delivered by this system per second. However, the high rate of activity is limited by the occurrence of the acidosis.

 

Besides the glycolysis there is another better known anaerobic metabolic process, i.e. the anaerobic alactic system which is able to provide an enormous amount of energy per second without production of lactate (a-lactic) and without using oxygen (anaerobic). This energy supply, however, is very limited in time (max. effort ca 5 sec). Its contribution in competition events as well as its importance regarding the interpretation of lactate test results is therefore also restricted.

 

Since the anaerobic glycolysis has to provide most of the fuel for the aerobic system and since this part of the anaerobic metabolism will never produce lactate, this anaerobic work will never be apparent in the lactate concentrations (neither in blood nor in the muscles). Moreover the better the swimmer’s endurance the greater this “hidden” anaerobic contribution. Indeed, it could be calculated that a world class swimmer provides about 25% more anaerobic work than a regional level swimmer to attain a blood lactate concentration of 4 mmol/1 (fig. 4).

 

Nearly the same difference in anaerobic contribution between a poor and good endurance trained swimmer was found for interval training exercises (fig. 5). Indeed, calculations revealed that to achieve 3 mmol/1 lactate in different aerobic interval exercises a well endurance trained swimmer (speed at 4 mmol/1 lactate on 400 m = 1.5 m/s, i.e. 4:26.7) has to provide 25% more anaerobic lactic energy than a less endurance trained athlete (speed at 4 mmol/1 lactate on 400 m =1.333 m/s, i.e. 5:00.0). Moreover, despite the same 3 mmol/1 lactate at the end of different aerobic interval exercises, the percentage of the total energy provided by the anaerobic lactic system increases as the intervals get shorter. The rate of anaerobic lactic energy supply however increases as the intervals of the sets lengthen. A longer rest period, 30 sec instead of 10 sec, does not influence the rate of anaerobic lactic energy supply, but allows the swimmer to swim faster and leads to a higher percentage of the total energy provided by the anaerobic lactic system.

 

In order to derive from lactate tests both key factors of the conditioning profile (the aerobic and anaerobic capacities) a software program has been built, based on the basic metabolic regulation model of Prof. Dr. A Mader. A comparative study on calculated and measured oxygen uptake using this software for runners showed very close likeness. Figure 6 shows the mean values of the aerobic and anaerobic capacities for different strokes and gender and type of swimmers (sprint, middle or long distance swimmers).

 

However, it would be too simplistic to assume that the coach’s job only consists in improving both the swimmer’s aerobic and anaerobic capacities. Indeed, the aerobic and anaerobic capacities need to be developed in the right proportion to each other in order to achieve the best performance in competition.

 

Examples:

*A distance swimmer with a too high anaerobic capacity cannot activate his aerobic (endurance) capacity to its highest level.

Result: he has a weak aerobic power and despite a good aerobic capacity he will register poor performances in long distance competitions.

 

*A sprinter with a too low aerobic capacity will acidify more quickly and will therefore not be able to activate his anaerobic capacity to its highest level.

Result: He has a weak anaerobic power. A better aerobic capacity would enable him to burn up more pyruvate instead of converting it to lactate and thus delay the acidification in the muscle cell. With the same anaerobic but a higher aerobic capacity he would be able to use his anaerobic capacity more (higher anaerobic power) and perform better on short events.

 

Adjusting both the aerobic and anaerobic capacities to each other (fine-tuning) is one of the main objectives of the precompetition phase.

 

The importance of the unraveling of the lactate readings into both capacities becomes obvious when comparing these results with those of a “classic” representation and interpretation of lactate test results.

 

Example 3: The “classic” method of interpreting and implementing lactate test results advised two runners with identical lactate curves to complete the same training volumes and intensities. According to the above mentioned lactate software, however, both athletes had, despite converging lactate curves, a different conditioning profile. Consequently the weakest athlete did not receive the appropriate training advice (fig. 9) and had to interrupt the training program repeatedly due to “overuse injuries.”

 

Since the aerobic/anaerobic threshold (lactate threshold or MaxLass, fixed or individual, aerobic or anaerobic threshold) is not a primary and basic component of the conditioning profile, but rather a derivation of the contribution of the aerobic and anaerobic capacities during a long lasting submaximal effort, we chose to abandon its assessment for defining the conditioning profile and/or its use for providing training advice. This does of course not mean that the aerobic/ anaerobic threshold is meaningless. Indeed, there is a very close relation between the aerobic/anaerobic threshold and the performance in a competition event lasting longer than 2 minutes. But, in order to trace back the key components of the swimmer’s conditioning profile the assessment of the aerobic and anaerobic capacities proved to be a much more significant and appropriate procedure (for more information see internet www.lactate.com).

 

Criteria for a reliable lactate test

  1. avoid influences of external factors by well planning the

tests in the training program.

 

  1. value always the aerobic and anaerobic part of the metabolic Using the software program as described above is actually the best way to reveal the strengths of both capacities. Without such a program a lactate test should at least consist in a submaximal effort of minimum 4 minutes and a short (between 30-45 sec) all-out effort. The latter enables an estimation of the anaerobic capacity. Based on these results it is possible to relativize the position of the lactate curve as well as any threshold value. For example:

*a high lactate reading after the short all-out test indicates a good anaerobic capacity; a favorable lactate curve will then certainly also stand for a good aerobic capacity allowing the swimmer to train intensively and reach good competition results.

 

*a low lactate reading after the short all-out exercise, on the other hand, will refer to a weak anaerobic capacity. A favorable lactate curve may then clearly overestimate the swimmer’s aerobic capacity. Consequently the training load (intensity as well as volume) must be kept rather low. It is not unusual for swimmers with such a conditioning profile to perform better in training or on lactate tests than in competition.

 

It must however be clear that a lactate reading after a short all-out effort provides only an estimation of the anaerobic capacity. Indeed, a swimmer who can really exploit maximally a poor anaerobic capacity may also reach reasonable lactate readings after the all-out exercise and can therefore be overestimated as far as his aerobic capacity is concerned. If, on the other hand, a swimmer, for whatever reason, sets in only a part of his anaerobic capacity, a low lactate reading will be found after the short all-out. This low lactate value is then rather an underestimation of his anaerobic capacity and will lead to an inappropriate reduction of training load. It is therefore always advisable to double-check the results of the all-out tests and the interpretation of the lactate readings with respect to the aerobic capacity with some qualitative observations made during training. These qualitative (not quantifiable = without a numeric value) observations are set up in a chart of criteria (tab. 2) to characterize the swimmers’ level of aerobic and anaerobic capacity. By means of this table the coach can typify and range his swimmers in one of the 4 categories below:

 

  1. swimmers with a high aerobic and a low anaerobic

capacity

  1. swimmers with a high aerobic and a high anaerobic

capacity

  1. swimmers with a low aerobic and a low anaerobic capacity
  2. swimmers with a low aerobic and a high anaerobic

capacity

 

This typification is very important to reduce the risks of misinterpretations and wrong training advice by means of the classic, less sophisticated lactate tests.

 

Let’s take an example:

A lactate test (e.g. 400 m free at submaximal speed followed by 15 min active rest and 100 m free all-out) revealed a good anaerobic threshold (e.g. a high 4 mmol/1 speed on 400 m) and a low maximal lactate level after the short all-out effort (the 100 m free max.). Based on the classic interpretation method these test results indicate that the swimmer has a good aerobic but a low anaerobic capacity. If this diagnosis fits with the swimmer’s typification by means of the capacities’ level chart (tab. 2), the coach may be quite confident about the interpretation of the lactate readings. If, on the other hand, the typification refutes the lactate results, i.e. a high anaerobic capacity deduced from the chart versus a low anaerobic capacity derived from the lactate results, caution is recommended. This contradiction may indicate that the low maximal lactate value after the 100 m free all-out is not due to a weak anaerobic capacity but rather to a lack of anaerobic power (low use of anaerobic capacity). The analysis of the effectuated training period has to shed light and adduce evidence to corroborate this hypothesis.

 

Whether the training for the next period should be adapted or not in consequence of this conditioning profile (high aerobic and anaerobic capacity and low anaerobic power) will actually depend on the current training phase:

*In the build-up phase there is no need for special training adjustments except to avoid training exercises such as voluminous extensive workouts which could further break down the aerobic power.

*In the pre-competition phase, on the other hand, the anaerobic power exercises have to receive the highest priority.

 

The above given example shows that it is extremely important to “confront” the classic interpretation of the lactate readings with the capacities’ level chart in order to validate the “lactate based” advice/objectives for the next training period. In the case of a contradictory diagnosis (classic interpretation of a lactate test versus capacities’ level chart) always choose for the least risky training advice. Say this were too “soft,” it is always possible to catch up, but once you have gone too far, i.e. trained too hard, it may take up to 6 weeks to recover.

 

We can conclude that lactate tests are actually the best and most practical procedure to reveal the metabolic performance of the muscle. However, it is very important to trace back the origin of the lactate value in order to understand and to define the underlying capacities (aerobic and anaerobic) of the metabolic process.

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