VARIOUS PHYSIOLOGICAL THRESHOLDS MOSTLY MEASURE DIFFERENT FACTORS IN SWIMMERS
Johnson, J. K., Battista, R. A., Pein, R., Dodge, C., & Foster, C. (2009). Comparison of monitoring tools for training intensity in swimmers. ACSM 56th Annual Meeting, Seattle, Washington. Presentation Number 1839.
This study determined the relationship between the blood lactate threshold and the ventilatory threshold in swimmers. Division III collegiate swimmers (M = 8; F = 7) performed an incremental tethered VO2 test and an incremental 6 x 200-m swim to measure the blood lactate threshold. The ventilatory threshold and respiratory compensation threshold were detected using the v-slope method and confirmed by ventilatory equivalents. Blood lactate threshold was determined as the first inflection in the blood lactate-velocity curve as well as the interpolated speed at a blood lactate level of 4 mmol. Heart rate threshold was defined as a percentage of maximum heart rate. Velocity and power output were calculated for each of the 200 m swims.
There was no significant relationship between heart rate at lactate and ventilatory threshold or between heart rate at lactate and respiratory compensation threshold. There was a minor correlation (r = 0.60) between the percent of maximum velocity at lactate and ventilatory threshold. The percent of maximum power at lactate threshold was significantly correlated with both percent maximum power at ventilatory threshold and respiratory compensation threshold. In contrast, no significant correlation was found between any of the thresholds in terms of percent of maximum heart rate.
Implication. These results suggest that lactate, ventilatory, and respiratory compensation thresholds represent individually separate swimming training intensities and are not broadly interchangeable or physiologically related.
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