Letter to the Editor

Li Y, Niessen M, Chen X, Hartmann U. Maximal lactate steady state in kayaking. Int J Sports Med 2014; 35: 939–942

We write this letter to express our concerns about the interpretation of results from a recent study of Li et al. [7], which aimed to determine the maximal lactate steady state (MLSS) during kayaking exercise.

Firstly, we would like to congratulate the authors for the study and the hard work that is known for conducting MLSS determination in athletes, due to numerous visits to laboratory. Indeed, the study presents a novelty, which was the direct measurement of MLSS, in a group of teenager kayakers. However, we have found some inconsistencies during the interpretation of the results, which should be addressed.

The main reason discussed by the authors to justify their study is related to the mode of exercise (i. e., kayaking), which involves little muscle mass exercising compared to cycling or running exercise, in light of usage of fixed blood lactate concentration ([La]) of 4 mM (i. e., LT4). Although the relationship between [La] at MLSS and different muscle mass engaged was demonstrated previously by Beneke at al. [3], we think there is also another likely reason for the higher [La] at MLSS, found by Li et al. [7].

Since Beneke et al. [4] reported the influence of test interruptions on MLSS determination, other studies have investigated the differences between the ‘continuous’ and ‘intermittent’ MLSS [2] [5] [6]. Beneke et al. [4] demonstrated that the inclusion of 30-s pause after every 5-min (as used by Li et al. [7]) modify the workload and [La] at MLSS when compared to continuous cycling protocol. The mean [La] value at MLSS was 4.7±1.5 mM (continuous protocol) and 5.7±1.3 mM (intermittent protocol using 30-s pauses; p>0.05 and Cohen’s Effect Size – ES=0.71), showing a trend to be higher when using the intermittent model [4]. The other 2 studies conducted by our group confirmed this fact, by using continuous and intermittent (1-min pause after every 5-min; ratio 5:1) MLSS determination during running ([La]=3.7±0.9 vs. 4.4±1 mM; p<0.02 and ES=0.80) and cycling ([La]=4.1±0.9 vs. 4.9±1.2 mM; p<0.01 and ES=0.76) [5] [6] respectively.

The conclusion by authors which [La] at MLSS was 5.4 mM in kayaking should be interpreted with caution. Based on aforementioned studies [4] [5] [6], one can observe that the interruptions (i. e., intermittent protocol) during the 30-min constant workload test might lead to higher [La] and exercise intensity compared to continuous protocol. We would like to point out this fact, since the workload for prescribing interval training at MLSS intensity should be adjusted in accordance to the intermittence used to determine it. Thus, we would suggest that the fixed [La] of 5 mM (i. e., LT5) should be used for kayakers when they intend to perform interval training at MLSS using long intervals (e. g., ~5-min) and reduced pauses (e. g., 30-s to 1-min). For continuous exercise if considering that the workload and [La] would be lower, LT4 could be used as an option.

Finally, there are other 2 confusing factors in the study: a) the age of the athletes, which could influence on [La] values [1]; and b) the small sample size (n=8 decreasing to 6). Therefore, in our opinion the generalization of results should be limited, considering these aspects.

• References

• 1 Almarwaey OA, Jones AM, Tolfrey K. Maximal lactate steady state in trained adolescent runners. J Sports Sci 2004; 22: 215-225
• 2 Barbosa LF, de Souza MR, Caritá RA, Caputo F, Denadai BS, Greco CC. Maximal lactate steady-state independent of recovery period during intermittent protocol. J Strength Cond Res 2011; 25: 3385-3390
• 3 Beneke R, Von Duvillard SP. Determination of maximal lactate steady state response in selected sports events. Med Sci Sports Exerc 1996; 28: 241-246
• 4 Beneke R, Hütler M, Von Duvillard S, Sellens M, Leithäuser RM. Effect of test interruptions on blood lactate during constant workload testing. Med Sci Sports Exerc 2003; 35: 1626-1630
• 5 Dittrich N, de Lucas RD, Beneke R, Guglielmo LGA. Time to exhaustion at continuous and intermittent maximal lactate steady state during running exercise. Int J Sports Physiol Perform 2014; 9: 772-776
• 6 Grossl T, de Lucas RD, Souza KM, Guglielmo LGA. Time to exhaustion at intermittent maximal lactate steady state is longer than continuous cycling exercise. Appl Physiol Nutr Metab 2012; 37: 1047-1053
• 7 Li Y, Niessen M, Chen X, Hartmann U. Maximal lactate steady state in kayaking. Int J Sports Med 2014; 35: 939-942