Training calculators
Add one interval workout to a mostly easy week while keeping hard minutes inside a conservative aerobic-base budget.
Updated 2026-06-15
Base-safe interval workout generator
Add one interval workout to a mostly easy week without letting hard minutes crowd out the aerobic base.
Sport
Interval focus
Aerobic base signal
Base readout
Ready for intervals
100% easy before
New interval dose
18 min
6% hard after
Hard cap
25 min
25 min budget left
Easy after
94%
282 min easy/base
Controlled threshold intervals
10-15 min easy jog, then a few relaxed pickups.
Main set
3 x 6 min controlled threshold.
Recover
3 min very easy between reps.
Cool down
10 min easy jog.
Placement
Keep at least 48 hours away from the long session or another hard day.
Session 1
Easy aerobic.
Session 2
Controlled threshold intervals, about 60 min total.
Session 3
Recovery easy.
Session 4
Easy aerobic.
Session 5
Long easy, about 90 min.
Rule 1
Replace one easy session with the interval session instead of adding extra weekly load.
Rule 2
Keep the session hard enough to create a signal, but controlled enough to repeat next week.
Rule 3
Keep the next day easy, and keep the long session easy unless the plan says otherwise.
How it works
Use this generator when you want to add intervals without turning a base week into a hard week. It estimates a conservative hard-minute budget from your current aerobic base, then suggests one workout and an easy-first sample week.
How to use it
- Choose running or cycling and the interval focus you want to add.
- Enter your current weekly aerobic minutes, easy sessions, existing hard minutes, consistency, and longest easy session.
- Use the generated workout as a starting point, replacing one easy session rather than adding a large new load.
Questions
Does this replace a coach-built plan?
No. It is a conservative planning tool. Use it to sanity-check the first interval workout in a base week, then adjust for injury history, race goals, and recovery.
Why does the generator cap hard minutes?
The goal is to add a clear stimulus without crowding out the easy aerobic volume that supports the base. If current hard minutes are already high, the tool may recommend holding intervals.
Can beginners use it?
Yes, but a fragile base should start with relaxed strides, spin-ups, or no formal intervals. Build consistent easy volume before adding hard threshold or VO2 work.