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O-50 Use of a mathematical model to monitor metabolic training adaptations in swimming: preliminary results of a long term follow-up of more than 900 swimmers of different performance level
  1. Jan Olbrecht
  1. Department of Biosystems, KU Leuven, Belgium

Abstract

Despite the common use of lactate tests to optimise training for top athletes, the interpretation and application of these tests are rarely underpinned with scientific evidence. This lack of scientific evidence inspires both support and criticism. Mader (1984) mathematically described the regulation of ATP-rephosphorylation in skeletal muscle applied to human activity. This model was used by Olbrecht (1989) to establish a simplified calculation scheme to quantify the oxidative and glycolytic energy delivery rates resulting in post exercise blood lactate concentrations. As, such outcomes are rarely documented in literature, we aim to report our findings with respect to gender, performance level and commonly used lactate test results.

A database was built with 6677 tests (crawl, breast- and backstroke) on 971 swimmers (f 448, m 523) among whom 136 with a follow-up of at least 4yrs, 210 selected for Olympic Games (56 medals) and 249 racing in Long Course World Championships (LCWC; 109 medals). All swimmers were classified according to their yearly selection for national (N), European (E) or LCWC/Olympic Games (W). The simplified calculation scheme was used to estimate both maximal capacities, oxygen uptake (VO2max) and lactate production (VLAmax), as well as the aerobic power (AEP = the oxygen uptake at MaxLass). Beside the model outcomes, common lactate test results such as the swimming speed at 4mmol/l lactate on 400m (V4400) and the highest lactate after a maximal effort (LAmax) were determined.

VO2max (ml/min*kg), VLAmax (mmol/s*kg), AEP (ml/min*kg) and V4400 (m/s) were significantly lower (p = 0.016 to 0.026) for female than for male swimmers and increased significantly (p = 0.001 to 0.006) from national to world performance level (mean±SE, from N to W, VO2max f: 52.5 ± 0.3 to 59.5 ± 0.4, m: 63.4 ± 0.2 to 71.4 ± 0.4 – VLAmax f: 0.37 ± 0.01 to 0.49 ± 0.01, m: 0.56 ± 0.01 to 0.75 ± 0.02 – AEP f: 38.2 ± 0.3 to 41.1 ± 0.4, m: 43.8 ± 0.2 to 46.4 ± 0.4 – V4400 f: 1.194 ± 0.002 to 1.245 ± 0.004, m: 1.277 ± 0.002 to 1.323 ± 0.004). The percentage of VO2max at V4400 (%V4400) and at AEP (%AEP) was significantly higher (p = 0.025 and 0.031) for female than for male swimmers and decreased significantly (p = 0.014 to 0.016) with the performance level (mean±SE, from N to W,%V4400 f: 72.9 ± 0.8% to 68.4 ± 0.7%, m: 68.0 ± 0.3% to 64.6 ± 0.6% –%AEP f: 78.1 ± 0.2% to 75.7 ± 0.4%, m: 74.7 ± 0.2% to 70.7 ± 0.4%).

Correlations between V4400 and VO2max (r = 0.53) and between LAmax and VLAmax (r = 0.07) were very weak but statistically significant. Differences between consecutive tests regarding V4400 and LAmax did not correlate with the concurrent differences in respectively VO2max and VLAmax. The only correlation, relevant for practice, was found between V4400 and AEP (r = 0.74, p < 0.001).

We can conclude that both capacities, VO2max and VLAmax, and the aerobic power AEP, estimated with the simplified model, reflect the performance level of the swimmers. The lack of correlations between VO2max and V4400 and between VLAmax and LAmax clearly shows that both capacities reflect different aerobic and anaerobic information as compared to common lactate test results such as V4400 and LAmax. The capacities characterise the underlying metabolic processes leading to the blood lactate and are necessary to accurately select appropriate training objectives and optimise training.

References

  1. Mader A. Eine Theorie zur Berechnung der Dynamik und des steady state von Phosphorylierungszustande und Stoffwechselaktivität der Muskelzelle als Folge des Energiebedarfs, Habilitationschrift Köln 1984: Deutsche Sporthochschule Köln.

  2. Olbrecht J, Mader A, Heck H, Hollmann, W. (1992). The importance of a calculation scheme to support the interpretation of lactate tests. In: D Maclaren, T Reilly, A Lees (Eds). Swimming Sciences VI, Biomechanics and medicine 1992 London, E & F.N. Spon; 243–249.

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