title: Step length and individual anaerobic threshold assessment in swimming.
abstract: Anaerobic threshold is widely used for diagnosis of swimming aerobic endurance but the precise incremental protocols step duration for its assessment is controversial. A physiological and biomechanical comparison between intermittent incremental protocols with different step lengths and a maximal lactate steady state (MLSS) test was conducted. 17 swimmers performed 7×200, 300 and 400 m (30 s and 24 h rest between steps and protocols) in front crawl until exhaustion and an MLSS test. The blood lactate concentration values ([La-]) at individual anaerobic threshold were 2.1±0.1, 2.2±0.2 and 1.8±0.1 mmol.l - 1 in the 200, 300 and 400 m protocols (with significant differences between 300 and 400 m tests), and 2.9±1.2 mmol.l - 1 at MLSS (higher than the incremental protocols); all these values are much lower than the traditional 4 mmol.l - 1 value. The velocities at individual anaerobic threshold obtained in incremental protocols were similar (and highly related) to the MLSS, being considerably lower than the velocity at 4 mmol.l - 1. Stroke rate increased and stroke length decreased throughout the different incremental protocols. It was concluded that it is valid to use intermittent incremental protocols of 200 and 300 m lengths to assess the swimming velocity corresponding to individual anaerobic threshold, the progressive protocols tend to underestimate the [La-] at anaerobic threshold assessed by the MLSS test, and swimmers increase velocity through stroke rate increases.
authors: Faculty of Sport, CIFI2D, University of Porto, Portugal. ricfer@fade.up.pt
authors: R J
authors: RJ
authors: Fernandes
authors: M
authors: M
authors: Sousa
authors: L
authors: L
authors: Machado
authors: J P
authors: JP
authors: Vilas-Boas
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D000328:Adult; D015308:Anaerobic Threshold / Q000502:physiology*; D000704:Analysis of Variance; D015444:Exercise / Q000502:physiology*; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D010807:Physical Endurance / Q000502:physiology; D013550:Swimming / Q000502:physiology*; D013997:Time Factors; D014743:Videotape Recording
chemical_list: D019344:Lactic Acid