Interval Training - Adapting the Workout to Your Level

Intensity
One of the most important principles involved in improving your physical condition is that you must exercise at rates that are intense enough to overload your body's physiological systems. An overload is achieved when you train at more intense rates than your normal daily activities. Taxing your muscles, heart, and lungs will improve strength, endurance and flexibility.

One error many swimmers make is that they believe merely putting in time will provide the health and appearance benefits they seek. They train at a pace that is no more intense than casual stroll and then wonder why they don't look and feel better.

You must overload to improve!
The best way to measure your training intensity is to count your heart rate immediately after each swim.

Time each swim.
Note your breathing rate after each swim.
Monitor your feelings of effort while you swim.

You can estimate your heart rate by counting your pulse rate for six seconds immediately after each swim. Add a zero to this count, and you will have your approximate exercise heart rate per minute.

Swimming Speed
After you have been training for a while, it is a good idea to complete some time trials in order to determine how fast you can swim some of the repeat distances that you frequently use in training. You can then estimate your training intensity by swimming at certain percentages of these "all-out efforts."

The proper intensity for aerobic training is somewhere between 75 and 90 percent of your maximum speed for a particular distance. More intense swims of 90-100 percent are primarily anaerobic and do not improve the aerobic training effect.

For example:
A swimmer completes a 100-yard swim in an all-out effort in 70 seconds. To calculate the amount of time the swimmer should complete the same 100 yards at an 80 percent effort multiply the time by .20 (swimming 20 percent slower than the original all-out effort) and add that to the original time.
100% - 80% = 20% or .20
70 seconds + 14.0 seconds = 84.0 seconds

Interval Training
Interval training is used to describe the system of multiple repeat swims used by most swim training enthusiasts. An example of a typical interval set is to swim ten 100-yard swims at 80 percent effort with approximately 20-30 seconds of rest between each swim. A WSU Masters coach might write the workout as:
10 x 100 Freestyle, 20-30 seconds rest
One important guideline should be applied to the number of repeats per set—the minimum number should provide an adequate aerobic overload. It is recommended that each set be a minimum of 10 minutes long including both swimming and resting time.

The most significant improvements in aerobic endurance are achieved when the rest periods between swims are less than one-half the time required to complete the swim. This relationship is expressed as a work/rest ratio of 2:1.

Short rest periods improve aerobic fitness more effectively than longer rest periods because they don't allow the swimmers enough time to recover between repeats. The most effective aerobic fitness training occurs when a swimmer begins the next repeat with their breathing and heart rate still considerably elevated from the previous swim. This condition causes physiological systems to remain overloaded for the entire set of repeats, including both the rest and work periods.

The Most Common Set
10 x 100 Freestyle on 1:40
This means swim ten 100-yard swims in 1:40 including rest. If you swim the 100 yards in 1:20 seconds, you'll have 20 seconds rest. If you swim the 100 yards in 1:35 seconds you'll only get 5 seconds rest.

Note: For best results, your interval time should be somewhere between 10-20 seconds rest for a 100-yard swim for the first swim of the set.

Adapting the Workout to Your Ability Level
WSU Masters provides workouts for all ability levels. If you cannot swim the workout as written, the coach will adapt either the distance or time so that you will finish the set with the rest of the group. Though you may not complete as many yards as another swimmer, the intensity of the yards that you do swim should be comparable to those of the more advanced swimmers.

For Example:
Group 1 Swimmers might do:
10 x 100 Freestyle on 1:45
Group 2 Swimmers might do:
10 x 75 Freestyle on 1:45

Both groups will take the same amount of time, but will swim differing amounts, though the intensity level of both groups should be the same.
The job of the coach is to keep the group working together.