If someone asked you, “What is your swimming base interval?” Would you know how to answer?  Knowing your “base” interval is the number one most important key if you want to improve your swimming whether it’s on your own or with a Master’s group. 

It’s much like running in the sense that you have to have tempo, fartlek, easy and long runs all pegged off a particular pace or heart rate. If you had no idea what your 5(k) race pace was, how difficult would it be to set an appropriate training program to improve your time? 

In swimming, “base” is the interval you can hold comfortably at a 70% effort for the duration of your swim. You need to be able to swim at least 20 minutes to find your base. Once "base" is determined all other pacing can be derived from your "base". 

How to find your “base”:
Warm up at least 400: Rest 10” between each: 100 swim, 100 drill (heads up polo swim and one arm swim drill with other arm in lead like superman), 100 kick on side one arm lead superman, 100 sw.

Then, 4 x 25: 5 strokes hard off the wall no breath getting the heart rate up. Finish the rest of the 25 as a relaxed swim with regular breathing pattern, R-20″. 

Main Set:
1 x 500 at Threshold-pace which is 85 to 90% (GET YOUR TIME!). Then take this total time, for example 9:40. Divide it by 5 (breaking it into time per 100 = 1:55). 1:55 is your BASE!

Next try swimming 5 x 100 on 1:55.
If you come into the wall with only 3 to 5” rest before you have to go again this is the perfect “base”. If you can’t make this set of 500 then I would add 5” to your "base" making it 2:00/100 yds. A Master’s Group Workout is written according to base. A set might look like this below:

‍
300 easy warm up.
5 x 100 on B (means swim 5 x 100 and leave on the 1:55)
5 x 100 on B+5 (means add 5” to your base and leave each 100 on 2:00)
5 x 100 on B-5 (means subtract 5 seconds and sprint but leave on the 1:50)

CD: 100 drills

Total—1900 yds.