Run or Ruck Substitution

You can substitute running or rucking as required by injury or whatever other circumstances with a bike, assault bike, rower, swimming or any other single mode endurance method. The key is converting the assigned programming to time.

**Note: These substitutions will do for general endurance improvement, but will not improve your running-specific endurance or rucking-specific endurance.**


Convert the assigned distance to the estimated time, the plug in to the Run Calculator or Ruck Calculator.

Example: 3 Mile run for time and follow on interval progressions.... Estimate what your 3-mile run time would be, then plug it into the Running Calculator. This will provide the intervals and per-mile pacing used in MTI programming. Use these times to determine what your assigned time will be on your substitute exercise (bike, assault bike, rower, etc). I estimate that I can run 3-miles in 21:00. I plug my estimated assessment time into the calculator, which says my 1-mile intervals should be 6:10-6:18. The programming is 2 Rounds of 1-Mile Intervals. So, on the bike (or whatever other substitute), I'll do 2 Rounds of very hard 6:10-6:18 intervals. Follow the distance, intensity, and/or rounds of intervals in the programming, and use the same training mode (bike, swim, etc).

Below is a reference chart for estimating assessment times when substituting the run or ruck.


  • Great: < 20 minutes
  • Good: 20:00-22:00
  • Average: 22:00-25:00
  • Below Average 25:00-30:00
  • Poor: > 30:00

Ruck Run

  • Good: 30-35 minutes
  • Average: 35-40 minutes
  • Poor: 40+ minutes