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Power Requirements for Swimming a World-Record 50-m Front Crawl

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Huub M Toussaint
Huub M Toussaint
Huub M Toussaint
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Martin Johannes Truijens at Vrije Universiteit Amsterdam
Martin Johannes Truijens
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61
Power Requirements for Swimming
a World-Record 50-m Front Crawl
Huub M. Toussaint and Martin Truijens
Peak performances in sport require the full deployment of all powers an athlete
possesses. How factors like mechanical power output, technique, and drag, each
in itself but also in concert with each other, determine swimming performance is
the subject of inquiry in this case study.
At constant speed, a swimmer is subjected to the resistive forces of water, that
is, drag (Fd) depending on a drag factor K and the swimming speed squared (v2;
see Equation 1). In order to overcome these resistive forces the swimmer has to
generate power (Pd, ie, force times velocity) according to
Pd = Fd · v = K · v2 · v = K · v3 (1)
In swimming, Pd is not equal to the total mechanical power (Po) a swimmer
has to deliver: The generation of propulsion in a uid always leads to the loss of
mechanical power that will be transferred in the form of kinetic energy from the
swimmer to the uid. Thus, in competitive swimming 2 important mechanical-power
terms of the total power (Po) can be discerned: power used benecially to overcome
drag (Pd) and power lost in giving water a kinetic-energy change (Pk). Hence,
Po = Pd + Pk (2)
The ratio between the useful mechanical power spent to overcome drag (Pd)
and the total mechanical power output (Po) is dened as the propelling efciency,
ep.1,2
eP
P
P
P P
pd
o
d
d k
= =
+
(3)
Combining Equation 1 with Equation 3, it appears that swimming speed
depends on power output, a drag factor, and propelling efciency:
vP e
K
=
⋅
o p
3
(4)
These theoretical considerations will be put to use by predicting individual
power requirements for swimming a world record in the 50-m freestyle based on
experimental data obtained with the MAD system (see Figure 1),3 in which the
swimmer pushes off from xed pads with each stroke. These 16 push-off pads,
The authors are with the Faculty of Human Movement Sciences, Vrije Universiteit, Amsterdam, The
Netherlands.
CASE STUDIES
International Journal of Sports Physiology and Performance, 2006;1:61-64
© 2006 Human Kinetics, Inc.
62 Toussaint and Truijens
Power Requirements in Swimming 63
placed 1.35 m apart, are attached to a 22-m-long, highly rigid aluminum rod that is
mounted 0.8 m below the water surface. The rod is connected to a force transducer
enabling direct measurement of push-off forces. Subjects use their arms only for
propulsion; their legs are oated with a small buoy. If a constant swimming speed is
maintained, the mean propelling force equals the mean drag force. Hence, swimming
1 lap on the system yields 1 data point for the speed-drag curve (see Figure 2).
Figure 1 — System to measure active drag (MAD system).
Figure 2 — Drag dependent on speed for subject JK.
62 Toussaint and Truijens
Power Requirements in Swimming 63
The MAD system can also be used to estimate propelling efciency. Given
that the xed push-off pads below the water enable the generation of propulsion
without loss of energy to the water, all-out sprints performed on the MAD system
enable faster swimming than all-out sprints when swimming “free.” Consider-
ing that power to overcome drag relates to swimming speed cubed and assuming
equal power output in two 25-m sprints (free and MAD), the ratio of speed cubed
sprinting all-out “free” relative to the speed cubed sprinting all out on the MAD
system reects ep:
eP
P
K v
K v
v
v
pd
o
free
MAD
3
free
3
MAD
3
= = ⋅
⋅
=
3
(5)
Swimmer JK is a world-class sprinter (50-m best time = 22.14 seconds) ranked
fourth at the 2003 World Championships in Barcelona and was the silver medalist
at the 2004 Olympic Games. The question was raised as to what power output is
required for JK to break the 50-m front-crawl world record (21.64 seconds).
Drag dependent on speed for JK equals 27.37v1.821 (Figure 2). The maximal
power output while swimming with arms only was found to be 220 W while reach-
ing a speed of 2.06 m/s (March 2003, see Figure 3). Sprinting with arms only in a
free-swimming condition, a speed of 1.88 m/s was obtained, yielding a calculated
propulsive efciency of 78%. When sprinting with arms and legs on the MAD
system, a speed of 2.22 m/s was achieved, requiring a total power output of 281 W.
With these performance factors a “free” swimming speed of 2.10 m/s was attained,
the start not included, yielding a 50-m time of 22.14 seconds.
Figure 3 — Power output swimming arms only (dots) and 50-m time (squares) for subject
JK. Note that not all tests are equally spaced in time.
64 Toussaint and Truijens
Breaking the world record requires a speed improvement of at least 2.3%
leading to a total power requirement of 320 W. Considering that the highest power
output ever measured in JK is 297 W (swimming with arms and legs) and that an
adequate taper should increase power output by about 10%,4 setting a world record
should be within this swimmer’s reach, at least when physical-performance factors
are taken into consideration.5
In this context it is interesting to note that the use of the MAD system as a
water-based strength-training device has been evaluated. A study revealed that a
group sprinting on the MAD system 3 times a week improved race times for free
swimming on 50 m, 100 m, and 200 m6 signicantly more than a control group.
This was attributed to a greater improvement in power measured on the MAD
system relative to the control group.
References
1. Alexander RM. Swimming. In: Alexander RM, Goldspink G, eds. Mechanics and
Energetics of Animal Locomotion. London, UK: Chapman & Hall; 1977:222-249.
2. Toussaint HM, Beelen A, Rodenburg A, et al. Propelling efciency of front crawl
swimming. J Appl Physiol. 1988;65:2506-2512.
3. Toussaint HM, de Groot G, Savelberg HHCM, Vervoorn K, Hollander AP, van Ingen
Schenau GJ. Active drag related to velocity in male and female swimmers. J Biomech.
1988;21:435-438.
4. Mujika I, Padilla S, Pyne D. Swimming performances changes during the nal 3 weeks
of training leading to the Sydney 200 Olympic Games. Int J Sports Med. 2002;23:582-
587.
5. Toussaint HM, Truijens MJ. Biomechanical aspects of peak performance in human
swimming. Animal Biol. 2005;55:17-40.
6. Toussaint HM, Vervoorn K. Effects of specic high resistance training in the water on
competitive swimmers. Int J Sports Med. 1990;11:228-233.
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Full-text available
  • Feb 2019
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Propelling efficiency of front crawl swimming
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Full-text available
  • Jan 1989
In this study the propelling efficiency (ep) of front-crawl swimming, by use of the arms only, was calculated in four subjects. This is the ratio of the power used to overcome drag (Pd) to the total mechanical power (Po) produced including power wasted in changing the kinetic energy of masses of water (Pk). By the use of an extended version of the system to measure active drag (MAD system), Pd was measured directly. Simultaneous measurement of O2 uptake (VO2) enabled the establishment of the relationship between the rate of the energy expenditure (PVO2) and Po (since when swimming on the MAD system Po = Pd). These individual relationships describing the mechanical efficiency (8-12%) were then used to estimate Po in free swimming from measurements of VO2. Because Pd was directly measured at each velocity studied by use of the MAD system, ep could be calculated according to the equation ep = Pd/(Pd + Pk) = Pd/Po. For the four top class swimmers studied, ep was found to range from 46 to 77%. Total efficiency, defined as the product of mechanical and propelling efficiency, ranged from 5 to 8%.
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Swimming Performance Changes During the Final 3 Weeks of Training Leading to the Sydney 2000 Olympic Games
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  • Nov 2002
The purpose of this study was to determine the magnitude of the swimming performance change during the final 3 weeks of training (F3T) leading to the Sydney 2000 Olympic Games. Olympic swimmers who took part in the same event or events at the Telstra 2000 Grand Prix Series in Melbourne, Australia, (26 - 27 August 2000), and 21 - 28 d later at the Sydney 2000 Olympic Games (16 - 23 September 2000) were included in this analysis. A total of 99 performances (50 male, 49 female) were analysed. The overall performance improvement between pre- and post-F3T conditions for all swimmers was 2.18 +/- 1.50 % (p < 0.0001), (range - 1.14 % to 6.02 %). A total of 91 of the 99 analysed performances were faster after the F3T and only 8 were slower. The percentage improvement with F3T was significantly higher (P < 0.01) in males (2.57 +/- 1.45 %) than in females (1.78 +/- 1.45 %). In conclusion, the pre-Olympic F3T elicited a significant performance improvement of 2.57 % for male and 1.78 % for female swimmers at the Sydney 2000 Olympic Games. The magnitude was similar for all competition events, and was achieved by swimmers from different countries and performance levels. These data provide a quantitative framework for coaches and swimmers to set realistic performance goals based on individual performance levels before the final training phase leading to important competitions.
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Biomechanical aspects of peak performance in human swimming
Article
  • Mar 2005
Peak performances in sport require the full deployment of all the powers an athlete possesses. How factors such as mechanical power output, technique and drag, each individually, but also in concert, determine swimming performance is the subject of this enquiry. This overview of swimming biomechanics focuses on three performance factors: (i) generation of propulsion in water; (ii) drag encountered by the body during swimming; and (iii) propulsive efficiency. Theoretical considerations will be put to use by predicting individual power requirements for swimming a world record in the 50 m freestyle based on experimental data.
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Effects of Specific High Resistance Training in the Water on Competitive Swimmers
Article
  • Jul 1990
A new training device derived from the MAD-system (system to measure active drag, Hollander et al. (8], providing fixed push off points in the water for swimming, the front crawl is described. The effects of training on this device (called POP from fixed Push Off Point) are determined by comparing the increase in performance of a training group (n = 11) to a control group (n = 11). The control group continued the normal training program. During ten weeks the training group followed the same program, but three times per week sprints performed on the POP were substituted for normal free swimming sprints. Despite the fact that training time and volume were equal, the training group showed a significantly greater improvement in force (from 91 to 94 N, 3.3%), velocity (from 1.75 to 1.81 m.s-1, 3.4%) and power (from 160 to 172 W, 7%) as measured on the MAD-system, and an increase in distance per stroke in free swimming. The training group showed a significant improvement in race times for 50 m (from 27.2 to 26.6 s), 100 m (from 59.3 to 57.4 s) and 200 m (from 129.6 to 127.3 s). It is concluded that the POP is a specific training device especially suitable for increasing maximal power output during swimming.
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Active drag related to velocity in male and female swimmers
Article
  • Feb 1988
  • J BIOMECH
Propulsive arm forces of 32 male and 9 female swimmers were measured during front crawl swimming using arms only, in a velocity range between 1.0 m s-1 and 1.8 m s-1. At constant velocity, the measured mean propulsive force Fp equals the mean active drag force (Fd). It was found that Fd is related to the swimming velocity v raised to the power 2.12 +/- 0.20 (males) or 2.28 +/- 0.35 (females). Although many subjects showed rather constant values of Fd/v2, 12 subjects gave significantly (p less than 0.01) stronger or weaker quadratic relationships. Differences in drag force and coefficient of drag between males and females (drag: 28.9 +/- 5.1 N, 20.4 +/- 1.9 N, drag coefficient: 0.64 +/- 0.09, 0.54 +/- 0.07 respectively) are especially apparent at the lowest swimming velocity (1 m s-1), which become less at higher swimming velocities. Possible explanations for the deviation of the power of the velocity from the ideal quadratic dependency are discussed.
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Mechanics and Energetics of Animal Locomotion
  • 222-249
  • Rm Alexander
  • Swimming
Alexander RM. Swimming. In: Alexander RM, Goldspink G, eds. Mechanics and Energetics of Animal Locomotion. London, UK: Chapman & Hall; 1977:222-249.