Link between stroking parameters and lactate concentration in swimming

Link Between Stroking Parameters And Lactate Concentration In Swimming

Dr. GJohn Mullen Biomechanics, Blog, Competition, Dr. John Mullen, Latest&Greatest 2 Comments

Background On Stroking Parameters and Lactate Concentration

Swimming is a unique sport where volumes much larger than the actual distance competed are used as training. Often times, this over distance training is used to improve “feel” for the water. Unfortunately, after long swims, swimming biomechanics are believed to become impaired. Moreover, many practices consist of repeated efforts of intermittent efforts, despite the notion that training at or below maximal lactate steady state is believed to improve endurance capacity.

The highest exercise workload that can be maintained over time without continual blood lactate accumulation has been termed maximal lactate steady state (MLSS). During exercise within a severe domain, changes in intramuscular fatigue-inducing factors such as phosphocreatine, inorganic phosphate, and hydration ions and the depletion of anaerobic sources yield exhaustion.

This study attempts to associate changes in stroke parameters (distance per stroke, stroke rate, and stroke index) with changes in blood lactate concentration when swimming at steady state and above MLSS. Moreover, this was performed at intermittent (MLSSi; similar to swimming practices) and continuous exercise (MLSSc).

What was done

Thirteen male swimmers who had participated in training for at least 3 years (17 km per week for at least 2 weeks prior to testing) were included in this study. The mean 400-m free performance recorded during the testing was 5:13.83, 69.3% of the world-record.

The swimmers performed a 400-m all-out swim to estimate aerobic speed. Then, MLSSc was determined by two to three 30-min sub-maximal constant speed swims and; 2) determination of MLSSi from the performance of the two to three 30 -min sub-maximal intermittent swims. To confirm correct speed was maintained an mp3 player attached to goggles beeped every time the swimmers were required to pass a red marker placed on the bottle of the pool.

For the MLSSc the swimmer performed a 30minute sub-maximal swim with blood lactate taken at the 10th and 30th minute. For the MLSSi, the swimmers performed a series of 12 repetitions of 150-s swims interspersed with 30 s of passive recovery (5:1).  

The time to complete 5 stroke cycles was recorded for each lap was used to calculate SR. DS was calculated as the ratio between the speed and SR. SI was the product of speed and DS.

Results

The swimmers were swimming faster at MLSSi but with similar average blood lactate and heart rate when compared to MLSSc. SR increased only between the 10th and 3rd min during the test swum above MLSSc. No significant interaction effect for SI was found. SI decreased significantly between the 10th and 30th min of the test swum at 102.5% MLSSc. SI decreased significantly between the 10th and 30th min of the test swum at and above MLSSi.

Conclusion

The main findings of this study were that: a) the speed at MLSS was greater in the intermittent condition and was the result of a greater SR; b) SR increased not only during the exercise swum above continuous MLSS (102.5 %) but also during the intermittent exercise performed at MLSS. However, DS and SI decreased throughout all exercise (i. e., from 10 th to 30 th min), irrespective of the exercise intensity (at and above the speed corresponding to MLSS) or the exercise condition (continuous and intermittent); and c) the changes in [La] were not related to changes in the stroking parameters. The hypothesis that there was a relationship between blood lactate accumulation and stroking parameters was not supported.

Practical Implication

This study challenges the notion that stroke alterations are due to biomechanical alterations. This brings to light the notion that fatigue and stroke disturbances are multi-factorial in regional-level freestyle swimmers.

Reference:

  1. Oliveira MF, Caputo F, Dekerle J, Denadai BS, Greco CC. Stroking Parameters during Continuous and Intermittent Exercise in Regional-Level Competitive Swimmers. Int J Sports Med. 2012 May 16.

Originally Posted June 2012

Comments 2

  1. a very interesting study that calls into question presuppositions. the practice of training remains very complex.
    Congratulations.

  2. Dave Marsh used to encourage speeding up stroke rates (counter-intuitive) during the last stages of the race. Do you think this is a great coping strategy to combat fatigue while simultaneously maintaining timing and “coupling” in the biomechanical context?

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