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238
Differences In Methods Determining The Anaerobic
Threshold Of Triathletes In The Water
Zoretić, d. 1 , Wertheimer, V. 2 , leko, G. 1
1 Faculty of Kinesiology, University of Zagreb
2 Croatian Academic Swimming Club „MLADOST“
The goal of this research is to examine the differences between three
various methods for determining the anaerobic threshold, i.e. differences
in heart frequencies with regard to the anaerobic threshold (FSanp-1,
FSanp-2, FSanp-3). 13 Croatian triathletes swam a progressive interval
test of 7 x 200 meters. The evaluation of functional ability was measured
by: maximum heart frequency, maximum speed, maximum lactate, anaerobic
threshold FS and anaerobic threshold lactate, for three different
methods. Results showed high correlation (r=0.91) between FSanp-1
(„intersection“ method) and FSanp-3 (D-max method), while the t-test
for dependant samples showed that no statistically significant differences
exist, the same demonstrating that those two different measures
for determining the anaerobic threshold are reliable in evaluating the
anaerobic threshold in swimmers.
Key words: „Intersection” method, 4 mmol/l method and d-max
method, swimming
IntroductIon
The main problem in testing swimmers and triathletes is the implementation
of a protocol in the water where ventilation parameters can’t be monitored
requiring tests that include monitoring metabolic parameters. Testing
these athletes outside the water does not ensure adequate and reliable
results due to the specificity of water training: decreased body temperature,
higher pressure volume of the heart, lower maximum heart frequency
and lower energy consumption (Maglischo, 2003). Various methods exist
for determining the anaerobic threshold based on the speed-lactate curve.
One of the methods used for establishing the anaerobic threshold is the
fixed lactate model proposed by Kindermann (1979), and upgraded by
Sjodin and Jacobs (1981) by introducing the OBLA (Onset of blood lactate
accumulation). Based on that initial model, the anaerobic threshold
was fixed at 4mmol/l, while the aerobic threshold precedes it at 2mmol/l.
A special interpretation of the lactate threshold arose after the existence
of individual differences in the blood lactate concentration, at the lactate
anaerobic threshold, was confirmed. The original method by Stegmann
and Associates (1981), defining the individual anaerobic threshold (IAT)
as the exercise intensity at which the speed-lactate curve changes its shape
from a curve to a straight linear (Maglischo, 2003). This method is also
known as the intersection method. Cheng and Kuipers have, in 1992, described
a new procedure, they call the D-max method, for determining the
anaerobic threshold, using a starting and terminating curve point. The line
is set by the basic course of variable change. Thereafter, a point is set on the
curve that is the farthest from the line. Said point represents a change in
trend and the authors believe it corresponds with the anaerobic threshold
(Maglischo, 2003).
The purpose of this paper is to determine whether statistically significant
differences exist between 3 various methods of anaerobic threshold
determination (the „Intersection” method, the 4 mmol/l method and the
D-max method), i.e. differences in heart frequencies at the anaerobic
threshold level (FSanp-1, FSanp-2, FSanp-3) during the swimmers’
progressive test. The importance of the anaerobic threshold determinant
lies in the subsequent simplicity in establishing training zones and
achieving planned training goals.
Methods
The subjects were a group of 13 Croatian triathletes of a recreational and
national level, of which there were 10 male and 3 female triathletes, at an