Cardio · 5 minute read
Building a cardio base when you've never done one
Most people who say they hate cardio have only ever done the wrong kind. Hard, short, breath-stealing intervals at full effort. That is a perfectly fine training method, but it is the wrong way to start.
A base is what makes the rest of the work possible. Built correctly, it converts a non-runner into a 5K finisher in 9 weeks. Built badly, it produces shin splints and a quit date.
Here is the ramp Forgd ships with, and the reasoning behind each phase.
Phase 1, weeks 1 to 3: walk-run intervals
Three sessions per week. Each session is 20 to 25 minutes total.
- Week 1: 1 minute jog, 2 minutes walk, repeated 7 times.
- Week 2: 1 minute jog, 90 seconds walk, repeated 9 times.
- Week 3: 90 seconds jog, 90 seconds walk, repeated 8 times.
The jogging pace is conversational. If you cannot say a full sentence aloud while running, slow down. Speed is irrelevant in this phase. Connective tissue (tendons, ligaments, the smaller stabilizers around the knee and ankle) adapts on a slower timeline than the cardiovascular system, and pushing pace before that tissue is ready is the most common cause of early injury.
Phase 2, weeks 4 to 6: continuous easy running
Three sessions per week. Sessions grow from 20 to 30 minutes.
- Week 4: 20 minutes continuous easy.
- Week 5: 25 minutes continuous easy with a 1-minute walk break in the middle if needed.
- Week 6: 30 minutes continuous easy.
"Easy" is defined by heart rate, not pace. If your watch supports zones, this is upper Zone 1 to lower Zone 2. If it does not, use the talk test: two-sentence conversations should be possible without breaking the running form.
You will be slow. That is the point. Aerobic capacity is built almost entirely below the lactate threshold, and pace adaptations come for free once the engine is bigger.
Phase 3, weeks 7 to 9: length plus one quality day
Three sessions per week, one of which adds a small amount of intensity.
- Week 7: 35 minutes easy, 30 minutes easy, 30 minutes with 4 x 1 minute pickups at 5K effort.
- Week 8: 40 minutes easy, 30 minutes easy, 30 minutes with 5 x 1 minute pickups.
- Week 9: 5K time trial (or your first event), 30 minutes easy, recovery walk.
The pickups are not intervals. They are 60 seconds at the pace you would hold for a hard 5K, with full walking recovery between. Their job is to teach your legs what "fast" feels like before race day, not to build fitness.
Pace versus heart rate
Almost every beginner runs the easy days too hard. The cure is to use heart rate as the ceiling and ignore pace entirely on Phase 1 and Phase 2 sessions. Your easy heart rate is roughly 180 minus your age, plus or minus 5. Drift above it and the run is no longer easy, no matter what your watch says about pace.
Phase 3 quality work uses pace and effort. Easy work uses heart rate.
When to skip a session
Resting heart rate up 7 or more from your baseline. Sleep under 6 hours. Soreness that affects your gait. Any of these and you walk that day instead. Missing a session never costs you fitness; pushing through one when you should not have done can cost you weeks.
What Forgd does
The Cardio module ships the 9-week base ramp out of the box. The plan reads from your Apple Health resting heart rate and sleep data each morning and downgrades the day's session automatically when the recovery flags trigger. You can skip the downgrade with one tap, but the prompt is there.
After week 9 the app branches. Most people ramp into a 10K plan; runners with a goal event get periodized programming through their race. Cyclists and rowers follow the same logic with sport-appropriate phases.
The slow weeks are not a limitation. They are the program.