Biomechanics and Medicine in Swimming XI

BiomechanicsandmedicineinswimmingXi
Mechanical and Propulsive Efficiency of Swimmers
in Different Zones of Energy Supply
Kolmogorov, s.V. 1,2 , Vorontsov, A.r. 2 , rumyantseva, o.A. 1 ,
Kochergin, A.B. 2
1 Pomor State University, Arkhangelsk, Russia
2 All-Russian Swimming Federation, Moscow, Russia
Dimensionless coefficients for mechanical and propulsive efficiency (e g ,
e p ) have been studied using physiological and biomechanical methods in
swimming various strokes. The research has been conducted in the three
zones of energy supply: below the threshold of anaerobic metabolism
(AT), above the zone of maximal oxygen consumption (VO 2 max ) and
in the zone between AT and VO 2 max . The highest values of e g and e p for
male and female swimmers have been revealed in the zone between AT
and VO 2 max . In all the three zones of energy supply the values of e g are
higher for male swimmers. At the same time the values of e p are equal
for male and female swimmers.
Key words: Metabolic and mechanical power, efficiency, velocity
IntroductIon
Development of efficient technologies to train swimmers assumes
solving of an important theoretical and practical problem of interdependence
between energy supply, on the one hand, and swimming
biomechanics, on the other one. In case of biological objects’ steady
non-stationary motion in water, at the first stage metabolic energy is
transformed with losses into mechanical one, which at the second stage
is transformed with additional losses into useful activity result, i.e. into
swimming velocity. To describe precisely basic mechanisms of the phenomenon
under study, this process of human swimming was formalised
in form of mathematic model (Kolmogorov, 1997):
v 0 =P ai × e g × e p /Fr �
110
f .d .�
, (1)
in which v 0 is mean swimming velocity at the competition or training
distance (m·s -1 ); P ai is power of active energetic metabolism (W);
e g is dimensionless coefficient of mechanical efficiency, i.e. ratio of total
external mechanical power (P to ) to P ai ; e p is dimensionless coefficient of
propulsive efficiency, i.e. ratio of useful external mechanical power (P uo )
to P to ; F r(f.d.) is frontal component of active drag force (N).
Hence, the goal of this research has been to investigate experimentally
regularities of metabolic energy transformation into swimming
velocity at different zones of energy supply on the basis of equation 1.
Methods
The research was conducted at the period of spring training mesocycle
lasting from January to April. Twenty-nine university swimmers (15
female subjects aged from 17 to 22 and 14 male subjects aged from
18 to 23) took part in the research. Correct studying of regularities of
metabolic energy transformation into useful activity result is possible
only in conditions when character and direction of training load carried
out by the subjects during the training mesocycle, are taken into
consideration. Therefore, the time of experimental investigation of this
process in the three different zones of energy supply was coordinated
with certain periods of purposeful technical and functional training. It is
this circumstance that explains the order of tests.
In February the first test was conducted in the zone of energy supply
below the threshold of anaerobic metabolism (AT). Test 1 was carried
out in a swimming pool on the basis of training series of 8×200 m by the
basic stroke with 45 s breaks.
In March the second test was conducted in the zone of energy supply
above the maximal oxygen consumption (VO 2 max ). Test 2 was carried
out in the flume, with peri-limiting metabolic power being applied in
swimming by the basic stroke. The work lasted one minute for sprinters
and two minutes for medium distance swimmers.
In April the third test was conducted in the zone of energy supply
between AT and VO2 max . Test 3 was carried out in the flume in the
course of training series of 3×1 minutes (for sprinters) and 3×2 minutes
(for medium distance swimmers) by basic stroke, intervals of work and
rest being altered as 1:1.
Preliminary, individual swimming velocities in all the three zones
of energy supply were calculated for each subject on the basis of special
tests in the swimming pool.
To define experimentally variables in equation 1, a complex of physiological
and biomechanical research methods was applied.
The power of active energetic metabolism (Pai , W) in all the three
tests was calculated as a ratio of energetic expenditures at the test distance
(E, J) to work time at this distance (t, s). Energetic expenditures
were defined experimentally by the method of indirect calorimetry. For
this purpose, all necessary gaseous parameters of the ventilation air were
measured with the help of the mobile system “MetaMax” and lactate
concentration was determined in capillary blood before and after the
test. When the research was conducted in the swimming pool (test
№ 1), gas analytical measurements were taken during rest breaks between
training distances. When the research was conducted in the flume
(tests № 2 and № 3), gas analytical measurements were taken before,
during and after the test. All experimental results were reduced to conditions
of STPD. Quantitative values of E were calculated on the basis
of special equations (Capelli et al., 1998; Zamparo et al., 1999), which
correspond entirely to the three studied zones of energetic supply and
are described in detail in the specified papers.
Total external mechanical power (Pto ), frontal component of active
drag force (Fr(f.d.) ) and useful external mechanical power (Puo ) were
defined using a biohydrodynamic method (Kolmogorov, 2008), which
consists of a complex of independent biomechanical and hydrodynamic
methods to measure necessary physical values. At first, total external
mechanical power (Pto max ) was defined by the method of small perturbations
at the maximal swimming velocity (v0 max ) (Kolmogorov et.
al., 1997). Afterwards, the corresponding value of Pto exp was calculated
for every experimental swimming velocity in the studied zones of energetic
metabolism (v0 exp ) on the basis of the well-known (Touissant and
Truijens, 2005) and verified experimentally dependence between these
parameters (Kolmogorov and Koukovyakin, 2001):
3 3
Pto exp =Pto max /v0max× v0exp . (2)
The frontal component of active drag force under conditions of swimmer’s
steady non-stationary forward motion (Fr(f.d.) ) was defined experimentally
for every experimental swimming velocity (v0 exp ) using the
corresponding hydrodynamic method (oriented specially to measure
this physical value) (Kolmogorov, 2008). This paper describes in detail
the theory, necessary mathematic models and practical technology to
define Fr(f.d.) within the whole range of v0 exp relevant for the research.
Useful external mechanical power (Puo ) was defined from the following
equation:
P uo = Fr (f.d.) × v0exp.
(3)
When the parameters, indicated above, were defined for every experimental
swimming velocity in the studied zones of energetic metabolism
(v 0 exp ), dimensionless coefficients of mechanical (e g =P to exp /P ai ) and propulsive
(e p = P uo / P to exp ) efficiency were calculated.
results
Tables 1 and 2 represent experimental results of the studied process in
dolphin swimming by a female subject and in brass by a male subject,
correspondingly. These tables give only key parameters of P ai , e g , e p , F r(f.d.)
and v 0 exp which are necessary to solve quantitatively equation (1) and