Based on:  P434-438: Swimming Fastest, Ernest Maglischo

Developed by Dick Bower of New Orleans, Louisiana, Cruise intervals allow coaches to individualise training speeds and send-off times for a large number of swimmers with a wide range of abilities who are all training in a limited number of lanes.  This is a good description of the situation within Manchester Triathlon Club.  The testing procedure used for calculating cruise intervals also allows swimmers to track their progress over time, helping with motivation. A number of coaches within the club have been trailing the Cruise Intervals method at sessions for the past 12 months. From October 2010 this will become standard across all sessions.

The first step in using this procedure is for swimmers to complete a test set of 10x100m to determine their ideal training speeds and send-off times.  Swimmers should maintain their fastest possible pace while taking exactly 10 seconds rest between each repeat.  Experienced swimmers can manage this themselves using the pace clock, novices may need the rest to be timed. Encourage swimmers to use even pacing, if they set off too hard and slow considerably during the test the result may not be valid.

Organising the test

To run a cruise interval test set for a group of swimmers follow the steps below:

• Write down everybody’s name and set the first swimmer in each lane off together
• Set remaining swimmers off at 5 or 10 second intervals
• Note each swimmers stagger ( how long after the lane leader they set off)
• As swimmers finish write down their finish time
• Once everyone has finished, give the group a recovery set to complete
• Whilst they are swimming subtract the stagger from their finishing time and add 10 seconds as the swimmers only rested 9 times. 
• Divide the total by 10 and record the quotient.
• Round up this time to nearest 5 seconds and record their Cruise Interval.

To help you do this I’ve produced a chart that shows the swimmers finish time on the left (with any stagger taken off) and the relevant cruise interval split times for vary distances across from that. A section of which is shown below. You can download the full file at the bottom of the page:

The repeat interval does not have to be 100m for the cruise interval test set.  It can be any repeat distance that will take swimmers 1:00-1:45 to complete. Remember that if a shorter repeat is used such as 75m, this will mean the resultant cruise interval send-off time will be for 75m repeats and will have to be adjusted based on the table above for other distances. It is possible to use this same procedure to find cruise interval send-off times for backstroke, breast stroke and Individual Medley, kicking and pulling, but not butterfly. At the present time we don’t use the test for this purpose.

Dates for running CI test sets are noted on the annual training plan.  Could all results be emailed to coaching@man-tri-club.org.uk so they can be shared with the relevant members of the coaching team.

Grouping Swimmers

Swimmers with the same cruise interval can then be grouped in one lane.  As our club has a wide range of abilities we currently have to group two cruise intervals within one lane at 25m sessions (e.g. swimmers with a CI of 1:30 & 1:35/100m) and 3 at 50m session (e.g. swimmers with a CI of 1:30, 1:35 & 1:40/100m) except for Squad sessions. If this is the case then faster swimmers should be asked to wear drag shorts or towels for some sets; female swimmers should be encouraged to swim with a pull buoy. Slower swimmers can be permitted to draft during some sets or use fins. We are now beginning to ‘stream’ sessions so that we can make best use of our pool time.  The tables below show how people with different Cruise Intervals should be grouped at each session (The Lane Distribution is subject to change so always check for the latest version):

If a new swimmers attends a session then guestimate the most appropriate lane for them based on any time trial info they know.  Their average time per 100m for 750m will provide a reasonable indication that you can work with.  Encourage them to complete the test set at the earliest opportunity.

Designing Sessions using cruise intervals

One of the great things about using cruise intervals is that it makes it easy to design endurance training sets without having to give specific target times for each swimmer.  The information below supports our Categories of Training document.

Basic Endurance Sets (E1/E2a/E2b)

For basic endurance set, instruct swimmers to swim at the slowest possible pace that enables them to make the designated cruise-interval turnaround time (E.g. 1.35).  For example:

• 20 x 100 IN 1.30 and OFF 1.35
• 10 x 200 IN 3.02 and OFF 3.10

Basic endurance sets can begin from 15 minutes of swimming time and progress to 30+ minutes.

Cruise PLUS can also be used for basic endurance training.  By adding 5-10 seconds to the cruise-interval turnaround time you will have more time to complete the designated repeat meaning you can swim slower.  This is useful when swimming long basic endurance sets, on recovery days, or when a swimmer is returning from illness.  Adding 5 seconds would enable all swimmers to swim comfortably at their E2a pace, whilst adding 10 seconds would be useful for E1 / Recovery swimming.

Threshold Endurance Sets (E3)

For threshold endurance sets, swim at the fastest maintainable repeat time going off on your designated cruise interval turnaround time.  Threshold sets will usually include 20 to 30 minutes of swimming time. For example:

• 15-20 x 100 IN 1:23 ON 1:35

Overload Endurance Sets (E4)

For overload endurance sets, swim at the fastest maintainable repeat time going off on your designated cruise interval turnaround time.  Overload endurance sets will usually include 20 minutes or less of swimming time. For example:

• 8-10 x 100 IN 1:20 ON 1:35

Cruise MINUS can be used for Overload Endurance training.  By subtracting 5 seconds from the cruise-interval turnaround time you will have less time to complete the designated repeat encouraging you to swim faster in order to make the send-off time.  Overload Endurance sets using Cruise MINUS will be no longer than 15 minutes of swimming. For example:

• 8-10 x 100 IN 1:23 ON 1:30

Cruise PLUS can be used for Overload Endurance training.  By adding 5-15 seconds to the cruise-interval turnaround time you can swim the repeats faster and have more time for recovery. For example:

• 8-10 x 100 IN 1:18 ON 1:45

Last-one-fast-one (LOFO)

You may see the abbreviation (LOFO) used in cruise interval sets.  It indicates that that the last repeat of a cruise interval set should be swum faster than the others.  The purpose if this will depend upon the set but can include:

• To add some ‘speed’ training to an endurance set. 
• To see whether the set has been swum at the appropriate pace. 
• As an indicators of over-reaching to prevent over-training.

Calculating send-off times for different distance reps: The send-off time doubles as the distance doubles.  So for a swimmer with a Cruise Interval Send-Off time of 1:35, the send-off times for different distances are listed below:

• 100m: 1.35, 200m: 3.10, 300m: 4.45, 400m: 6.20
• 500m: 7.55, 600m: 9.30, 700m: 11.05, 800m: 12.40

An easy way to calculate this is to carry around a copy of the swim split calculator available in the file library. Simply find the cruise interval send-off time in the 100m column and read across for the send-off time for other distances.