LACTATES AND COMPETITIVE PERFORMANCES
Bonifazi, M., Martelli, G., Marugo, L., Sardella, F., & Carli, G. (1993). Blood lactate accumulation in top level swimmers following competition. The Journal of Sports Medicine and Physical Fitness, 33, 13-18.
This study involved extensive testing of swimmers at four 25 m Italian Championship and "European Cup" meets. Lactates were taken 5 min after event completion [Harrison et al. (1992) say it should be 1 minute after - see reference this issue of Coaching Science Abstracts].
Relationships also were determined for crawl stroke events between:
- Two 400 m repetitions at constant speeds separated by a 20 min rest period, at 85% and 100% of maximum speed. The speed equivalent to 4 mM was interpolated between the measures and deemed to be the criterion of aerobic capacity (V4).
- Best time in crawlstroke races.
The day after competitions, two submaximal trials were conducted in a previously performed event. Those two values were joined in a La--Velocity graph and extrapolated to the La obtained after the previous race to reveal an estimated velocity. That relationship was determined.
The statistical analyses consisted of many ANOVA and Student t tests for comparisons and many individual correlations to determine the significance of relationships. These procedures raise the specter of inflated alpha levels due to the increased probability of obtaining findings purely through chance because of the many opportunities provided.
- In 5 of 13 events males recorded significantly higher La values than females. There were more events where there was no difference than difference.
- When V4 was related to crawl stroke events, it was related to only 400 and 800 m events in females, and 200, 400, and 1500 m events in males. This supports the assumption that V4 primarily is an aerobic test for it relates to those events that are very markedly aerobic.
- When La measures were compared between events, in both sexes the following differences were significant:
- 50 FR with 200 FR and 800/1500 FR;
- 100 FR with 800/1500 FR;
- 400 FR with 800/1500 FR; and
- 800/1500 FR with all BR, BK, FL, and IM events.
A variety of other sex dependent differences were revealed but did not seem to "make sense" from an hypothesized energy demand by event interpretation.
- When all data were pooled, the modal value and the range of all values was less for women than for men. This suggests that women respond differently to men, particularly in terms of magnitude, in La in swimming.
- When the two post-event, submaximal swims were performed and the La "line-of-fit" extrapolated to the velocity corresponding to race La, the relationship between each expressed as (m/s)3 was r = .98 (Pearson Product Moment), an extremely high value.
The observed La levels were less than those reported for running events of a similar duration. This is because, in swimming:
- there is a smaller active muscle mass;
- a lower maximal oxygen uptake;
- an increased muscle blood flow during work; and
- a different body position.
The lower levels are in agreement with Howat and Robson (1992 - see reference this issue of Coaching Science Abstracts). If La values are lower for swimming than running, one has to question why the 4 mM, a running value, was selected for comparison with swimming speeds? It would seem that it would be better to use 3 mM for women and 3.5 mM for men as determined by Howat and Robson for the "criterion of aerobic capacity".
The mechanisms for women usually recording lower La values than men are as follows:
- they have an inborn "glycogen sparing" metabolic profile (they use fats more efficiently);
- there is less pronounced glycolytic activity in skeletal muscle,
- they have a higher capacity for lactate oxidation, and
- they have a smaller active muscle mass.
However, despite those differences the majority of events displayed no significant difference between the La values recorded by the groups according to sex.
Several references that were cited were particularly selective and did not reveal others which contradict those chosen to serve as the basic premises for arguments used to derive conclusions.
- The few and often inconsistent differences between events, sex groups, and submaximal performances suggest that La is not a particularly valuable index of swimming work. The authors conclude that the only notable finding of the study was the high relationship between the post-event submaximal swims and the extrapolated event speed. It would be interesting to determine such a relationship if the submaximal performances were conducted prior to competitions rather than after.
- La values in competitions are not particularly sensitive to the demands of events. In general, 800 and 1500 m events differ to the majority of other events in terms of the level of La demonstrated 5 min after the completion of races.
- One should be wary of placing much emphasis on La recordings associated with swimming training or competitive performances.
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