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Effect of exercise-induced dehydration on lactate parameters during incremental exercise.
Int J Sports Med. 2005 Dec; 26(10):854-8.IJ

Abstract

Cyclists often use heart rate limits or power output zones, obtained from lactate parameters during incremental exercise testing, to control training intensity. However, the relationship between heart rate or power output, and blood lactate can be changed by several factors including dehydration. Therefore, in the current study we investigated the impact of exercise-induced dehydration on lactate parameters during graded exercise. Nine triathletes completed two test sessions in random order, with a 1-week interval. Each session consisted of 2 graded cycling tests to exhaustion (pretest, posttest), interspersed by a 2-h endurance exercise bout. In one session the cyclists received adequate fluid replacement (EH, 1350 ml . h (-1)) whilst in the other session dehydration was not prevented (DH, 225 ml . h (-1)). Subjects received equal amounts of carbohydrates (150 g) during either condition. The 4-mmol lactate threshold (OBLA) and the d (max) lactate threshold (TH-Dm) were calculated from the power : lactate curves. Weight loss was 0.5 +/- 0.3 kg in EH versus 2.5 +/- 0.2 kg in DH (p < 0.05). Heart rate (HR) at TH-Dm remained unchanged in all test occasions. Conversely, HR at OBLA increased by approximately 10 beats . min (-1) from the pretest to the posttest (p < 0.05), in both EH and DH. Compared to the pretest, in the posttest power output at TH-Dm was reduced (minus approximately 12 %, p < 0.05) in DH, but not in EH. Gross mechanical efficiency at TH-Dm was 20.7 +/- 1 % in the pretest in EH and was not different from the pretest value in DH (21.4 +/- 0.7 %, n.s.). Gross efficiency decreased in the posttest in DH (18.4 +/- 0.6 %, p < 0.05), but not in EH (20.2 +/- 0.8 %, n.s.). It is concluded that heart rate rather than power output should be used to monitor training load in cyclists exercising in environmental conditions predisposing to dehydration. Furthermore, in the latter condition, adequate rehydration is essential to preserve optimal mechanical efficiency.

Authors+Show Affiliations

Exercise Physiology and Biomechanics Laboratory, Department of Kinesiology, Faculty of Physical Education and Physiotherapy, K. U. Leuven, Tervuursevest 101, 3001 Leuven, Belgium.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

16320170

Citation

Van Schuylenbergh, R, et al. "Effect of Exercise-induced Dehydration On Lactate Parameters During Incremental Exercise." International Journal of Sports Medicine, vol. 26, no. 10, 2005, pp. 854-8.
Van Schuylenbergh R, Vanden Eynde B, Hespel P. Effect of exercise-induced dehydration on lactate parameters during incremental exercise. Int J Sports Med. 2005;26(10):854-8.
Van Schuylenbergh, R., Vanden Eynde, B., & Hespel, P. (2005). Effect of exercise-induced dehydration on lactate parameters during incremental exercise. International Journal of Sports Medicine, 26(10), 854-8.
Van Schuylenbergh R, Vanden Eynde B, Hespel P. Effect of Exercise-induced Dehydration On Lactate Parameters During Incremental Exercise. Int J Sports Med. 2005;26(10):854-8. PubMed PMID: 16320170.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effect of exercise-induced dehydration on lactate parameters during incremental exercise. AU - Van Schuylenbergh,R, AU - Vanden Eynde,B, AU - Hespel,P, PY - 2005/12/2/pubmed PY - 2006/3/17/medline PY - 2005/12/2/entrez SP - 854 EP - 8 JF - International journal of sports medicine JO - Int J Sports Med VL - 26 IS - 10 N2 - Cyclists often use heart rate limits or power output zones, obtained from lactate parameters during incremental exercise testing, to control training intensity. However, the relationship between heart rate or power output, and blood lactate can be changed by several factors including dehydration. Therefore, in the current study we investigated the impact of exercise-induced dehydration on lactate parameters during graded exercise. Nine triathletes completed two test sessions in random order, with a 1-week interval. Each session consisted of 2 graded cycling tests to exhaustion (pretest, posttest), interspersed by a 2-h endurance exercise bout. In one session the cyclists received adequate fluid replacement (EH, 1350 ml . h (-1)) whilst in the other session dehydration was not prevented (DH, 225 ml . h (-1)). Subjects received equal amounts of carbohydrates (150 g) during either condition. The 4-mmol lactate threshold (OBLA) and the d (max) lactate threshold (TH-Dm) were calculated from the power : lactate curves. Weight loss was 0.5 +/- 0.3 kg in EH versus 2.5 +/- 0.2 kg in DH (p < 0.05). Heart rate (HR) at TH-Dm remained unchanged in all test occasions. Conversely, HR at OBLA increased by approximately 10 beats . min (-1) from the pretest to the posttest (p < 0.05), in both EH and DH. Compared to the pretest, in the posttest power output at TH-Dm was reduced (minus approximately 12 %, p < 0.05) in DH, but not in EH. Gross mechanical efficiency at TH-Dm was 20.7 +/- 1 % in the pretest in EH and was not different from the pretest value in DH (21.4 +/- 0.7 %, n.s.). Gross efficiency decreased in the posttest in DH (18.4 +/- 0.6 %, p < 0.05), but not in EH (20.2 +/- 0.8 %, n.s.). It is concluded that heart rate rather than power output should be used to monitor training load in cyclists exercising in environmental conditions predisposing to dehydration. Furthermore, in the latter condition, adequate rehydration is essential to preserve optimal mechanical efficiency. SN - 0172-4622 UR - https://www.unboundmedicine.com/medline/citation/16320170/Effect_of_exercise_induced_dehydration_on_lactate_parameters_during_incremental_exercise_ L2 - http://www.thieme-connect.com/DOI/DOI?10.1055/s-2005-837460 DB - PRIME DP - Unbound Medicine ER -