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Re: Response to: Endurance in young athletes: it can be trained

Dear Editor

With regard to the Leader by ADG Baxter-Jones and N Maffulli [1] we would like to extend our appreciation to the authors for their interest in this never ending “hot debate”.

The authors clearly point out difficulties and potential pitfalls of exercise testing, exercise prescription and the interpretation of acute responses and of the chronic adaptation to exercise training during growth and maturation.[1] We totally support the conclusion that appropriate endurance training in children and adolescents lowers blood lactate levels (BLC) at given workload and improves peak oxygen uptake and performance at anaerobic threshold (AT). However, we strongly feel that the comments on AT especially with respect to so called “lactate criteria” do not consider the current state of knowledge in this field of science.

There are a huge number of different concepts of AT that use BLC, ventilatory measures or the combination of both.[2] In theory the BLC based concepts of AT are supposed to identify the highest exercise intensity at which a steady state of BLC can be identified during a prolonged constant workload. The corresponding steady state BLC is defined as the maximal lactate steady state (MLSS).[3,4] Depending on the testing condition AT measurements determine a workload which correlates with the MLSS workload but which may not be identical to the latter.[3] Therefore behaviour of the BLC during prolonged constant workload exercise conditions has been systematically analysed for individuals aged between 9 and 32 years.[5-11] Differences in experimental methods have been analysed [5] and the procedures were validated against methods previously established and exclusively used in the adult population.[12] The results show that at given exercise intensities up to the level of the workload corresponding to the MLSS the BLC appears to be independent of age across the whole range of maturation from pre-puberty to adulthood.

We agree totally that the acute response and chronic adaptation to exercise of young athletes is not yet fully understood. However, based on the current state of knowledge there is no evidence for the statement:
“In general, BLC levels are lower in children and adolescents than in adults at any given exercise intensity”

and in fact experimental results support the opposing view point.

References

(1) Baxter-Jones ADG and Maffulli N. Endurance in young athletes: it can be trained. Br J Sports Med 2003; 37: 96-97.

(2) Loat CE, Rhodes EC. Relationship between the lactate and ventilatory thresholds during prolonged exercise. Sports Medicine 1993;15(2):104-115.

(3) Beneke R. Anaerobic threshold, individual anaerobic threshold, and maximal lactate steady state in rowing. Med Sci Sports Exerc 1995;27(6):863-867.

(4) Heck H, Mader A, Hess G, et al. Justification of the 4-mmol/l lactate threshold. Int J Sports Med 1985;6:117-130.

(5) Beneke R, Schwarz V, Leithäuser R et al. Maximal lactate steady state in children. Ped Exerc Sci 1996;8(4):328-336.

(6) Beneke R, Heck H, Schwarz V, et al. Maximal lactate steady state during the second decade of age. Med Sci Sports Exerc 1996;28(12):1474-1478.

(7) Beneke R, Leithäuser RM, Schwarz V, et al. Maximales Laktat-Steady- State bei Kindern und Erwachsenen. Dtsch Z Sportmed 2000;51:100-104.

(8) Heck H. Laktat in der Leistungsdiagnostik. Wissenschaftliche Schriftenreihe des deutschen Sportbundes. Schorndorf: Verlag Karl Hofmann, 1990.

(9) Mocellin R, Heusgen M, Korsten-Reck U. Maximal steady state blood lactate levels in 11-year-old-boys. Eur J Pediatr 1990;149: 771-773.

(10) Mocellin R, Heusgen M, Gildein HP. Anaerobic threshold and maximal steady-state blood lactate in prepubertal boys. Eur J Appl Physiol 1991;62:56-60.

(11) Williams JR, Armstrong N. Relationship of maximal lactate steady state to performance at fixed blood lactate reference values in children. Ped Exer Sci 1991;3: 333-341.

(12) Beneke R. Methodological aspects of maximal lactate steady state – implications for performance testing. Eur J Appl Physiol 2003;89:95-99.