Costill, D. L. (1998). Training adaptations for optimal performance. Invited lecture at the Biomechanics and Medicine in Swimming VIII Conference, Jyvaskulla, Finland.

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"We are led to think that performances are related to the volume of training that athletes do, and I want to show you this is totally wrong because we have seen that performances continue to improve while not being related to volume."

"Different individuals have different responses to the same training. By training everybody the same way, which we are forced to do because of facilities, etc., we may destroy as many talents as we produce."

"Skill (biomechanics) is extremely important in swimming. Physiology does not select an Olympic champion. Skill is the major factor. Without swimming skill, one can never benefit from physiological changes."


Swimming strength is important. Upper body strength is a good predictor of success in swimming. If sprint swimming was correlated to power, and most events in swimming are sprints, the coefficients would be significant. Sprinters can be differentiated from distance swimmers by the power they can generate.

Using semi-tethered force measurement training responses can be monitored. After pre-season measurements are recorded swimmers typically get stronger. But then, as the training load continues to increase even more, arm power gets weaker. At the highest training loads, arm power is even less than in the pre-season state. Losing arm strength loses sprint capacity. Most coaches recognize this loss of strength with excessive training and program a taper so that power can be recovered. A taper enhances arm-power recovery and performances.

How Much Training?

Costill has shown that a group of mature swimmers training once a day, when matched to a group training twice a day, recorded similar performance levels when both groups changed to training only once a day. The two-a-day group showed the classic loss of arm power and performance. At the same time the one-a-day group exhibited stable sprint performances. After taper, both groups performed similarly. What was the value in the extra work?

Does Land Strength-training Help?

Two matched groups of mature swimmers, one swimming only, the other performing dry-land strength training, were tracked and measured. Both groups improved in swimming power and strength gains. The supplementary land-training provided no added benefit. Costill attributes the lack of specificity in the land-training to the lack of transfer. He stated: "You can gain strength by swimming. If you want to overload the muscle then do sprint swimming".


There are two ways to taper: reduce volume initially and keep a low volume until competition or gradually reduce the training volume. For swimmers who tend to be overtrained, the first alternative is preferable.

When comparing performances before and after tapering at least a 3.5% 'improvement should be expected in both male sprinters and distance swimmers.

Females do not get the same magnitude of benefit from a taper as do males. Females should be expected to improve 1.4%. Costill attributes the gender difference to the fact that women do not recover as much arm power in a taper as do men.

Mood changes. Swimmers' moods change with adaptation to training. However, once adaptation is complete moods return to normal. It is only in overtrained swimmers that mood states are altered. Since mood does not change between adapted states and during taper, a taper is not psychological (at least from a mood standpoint).

Muscle fiber changes. When muscles rest in a taper, the Type II muscle fibers (fast twitch) get bigger. The number of myosin filaments increases in the appropriate muscles' fibers. The Type II fibers are faster and larger and demonstrate increased peak tension after a taper. It is in the Type II muscle fibers that most of the taper effect occurs.

Implicatioons. Large training volumes for swimming are hard to justify from a physiological viewpoint. Large volumes require slower velocity, which in turn increases the amount of non-specific training.

  1. Sprint training is needed to maintain and improve sprinting power and performance.
  2. Excessive training volumes can reduce Type II fiber power, which results in depressed performances.
  3. Supplementary strength training does little if anything to improve swimming power.
  4. An adequate taper restores muscle power and sprinting speed.
  5. Females (+1.4%) do not respond to a taper with the same magnitude as do males (+3.5%).

Return to Table of Contents for Training for Swimming.

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