Missing one session: what to do
Missing a single session mid-week is not a problem. If you missed a Tuesday easy run, do not try to cram it in on Wednesday alongside your planned Thursday quality session. Just skip it and continue. One easy run has no measurable effect on a 12-week plan.
If you missed a quality session (tempo or intervals), you have two options: move it by one day if your schedule allows, or skip it entirely. Do not double up — running a hard session and trying to catch up a second hard session the following day increases injury risk without meaningful fitness gain.
The session that cannot be moved or skipped is the long run. If you miss your long run for the week, either shift it by one or two days (running Sunday instead of Saturday), or accept a short-run week and continue normally the following week with the next scheduled long run distance. Don't try to make up the distance later.
Missing a full week due to illness
If you miss an entire week due to a cold or flu, drop back one week in the plan and continue. If you were in week 6, return to week 5 and progress from there. This accounts for the aerobic detraining that occurs during illness and gives your body a genuine recovery before you resume harder sessions.
Do not return to quality sessions (tempo, intervals) on the first day back after illness. Run 2–3 days of easy running at reduced effort before attempting anything hard. Your cardiovascular system recovers faster than your immune system, and runners frequently re-injure or relapse by returning to hard training too quickly.
Illness-related missed weeks are different from injury-related ones. After illness, return to running as soon as you feel genuinely well — not just symptom-free. With injury, the clearance to run comes from the injury resolving, and the rebuild is more gradual.
- →1 week missed (illness): drop back one week in plan, resume with easy runs first
- →1 week missed (travel, work): continue normally from where you stopped
- →2 weeks missed: return to previous training phase, rebuild for 1–2 weeks
- →3+ weeks missed: reassess goal time and race date — a 12-week plan needs 12 weeks
Missing two or more weeks
Two weeks of complete inactivity results in measurable aerobic detraining — roughly 5–8% reduction in VO2max. This is recoverable, but it changes your plan trajectory. Don't resume at the week you left off.
Return to the previous training phase. If you were in the speed phase (weeks 7–9) and missed two weeks, return to the strength phase (weeks 4–6) for 1–2 weeks before resuming speed sessions. Your long run should be shorter than where you were — rebuild distance at the 10% rule.
If the gap was caused by injury, get clearance before returning to quality sessions regardless of how much time has passed. Bone stress injuries, IT band syndrome, and plantar fasciitis all require full resolution before resuming hard training. Running through these usually extends the injury timeline significantly.
How to adapt your plan rather than restart it
Restarting a plan from week 1 after a mid-plan disruption is almost never the right answer. The aerobic fitness you built in weeks 1–5 doesn't fully disappear in two weeks. Rebuilding the entire base phase wastes that fitness and extends your training timeline unnecessarily.
Adaptation means adjusting where you re-enter the plan based on what you missed and why — not discarding the plan. A runner returning from one week of illness re-enters one week earlier than they left. A runner returning from two weeks returns to the previous phase. A runner returning from four or more weeks reassesses whether their race date is still achievable.
Your PaceForm PDF includes a rules page — 'When life gets in the way' — that covers every missed-session scenario. These rules follow the same principles as the original plan: the 10% mileage rule, recovery week placement, and phase sequencing. Use it to make the call yourself rather than guessing.
When should you consider moving your race date?
Consider moving your race if you have missed 4 or more weeks of structured training, particularly in the later phase of the plan. Missing 4 weeks of the speed or taper phase removes the sessions that specifically prepared you for race pace and race conditions. Starting that race puts you at injury risk for a result that won't reflect your real fitness.
Also consider moving the date if the disruption was due to injury and you returned to running fewer than 4 weeks before the race. Four weeks is the minimum time needed for the body to consolidate basic race readiness — anything less means racing undertrained.
Moving a race is not failure. Running an undertrained race that sets your fitness back by weeks or months is the more expensive outcome.