Interval Readiness Checklist: Proceed, Modify, or Postpone

Structured intensity sessions are where adaptations happen — but low-quality hard sessions are wasted stress. Use this short, science-based interval readiness checklist as a pre-interval gate: three signals, three clear outcomes. This is not caution. It is quality control.

Why a pre-interval gate matters (and what to check)

Hard work only pays when you can execute it well. A quick gate prevents poor VO2 max intervals or threshold sessions from becoming needless fatigue. Check three signals in order:

1. Sleep & recovery
2. Readiness trend (HRV / RHR / TSB)
3. Warm-up response (power/HR/cadence response and perceived effort)

If all three are green: execute the planned session. If signals are mixed: reduce the dose (shorter or fewer intervals, lower intensity). If signals show red flags: pivot to aerobic support work (Zone 2 or active recovery) and protect adaptation.

Signal 1 — Sleep & recovery

What to look for

• Last night’s sleep duration and quality: <6 hours or fragmented sleep is a cautionary signal.
• Recent recovery metrics (WHOOP/Oura/N+One readiness): a notably low recovery score or elevated resting heart rate (RHR +4–6 bpm above baseline) is a red flag.

Practical thresholds

• Green: ≥7 hours of solid sleep or recovery score within your normal range.
• Amber: 6–7 hours, light sleep or moderate reduction in recovery score — consider dose reduction.
• Red: <6 hours, or recovery score severely depressed, RHR elevated >6 bpm — pivot to support work.

Why it matters

Sleep drives the physiological processes that consolidate training adaptations. Poor sleep blunts power output and increases injury and illness risk (see Fullagar et al., Sports Med.). Treat sleep as the first gate, not a suggestion.

Signal 2 — Readiness trend (short-term context)

What to read

• Use a 3–7 day trend in HRV, resting HR, and TSB (N+One aggregates CTL + ATL = TSB for you).
• Look for direction and magnitude: is the athlete trending toward freshness or fatigue?

Decision rules

• Three green signals (sleep + steady HRV/RHR + neutral/positive TSB): proceed.
• Mixed signals (one low, others OK): reduce dose — fewer intervals, shorter duration, or drop from VO2 to threshold/sweet spot.
• Red (HRV sharply down, RHR up, TSB strongly negative): postpone hard intervals.

Practical example: VO2 max intervals vs threshold session

• If HRV is slightly depressed but TSB is neutral, swap VO2 max intervals for a shorter threshold session or a sweet-spot block. If HRV is sharply down and TSB <-10, avoid both — go aerobic support.

(For more on reading TSB without anxiety, see our guide.)

Signal 3 — Warm-up response (the decisive gate)

A 20–30 minute warm-up is not optional — it’s diagnostic.

What to watch during warm-up

• Power: can you hit 30–60s at 95–105% of planned interval intensity without extreme struggle?
• Heart rate: is HR creeping to interval levels during the warm-up? Rapid early HR rise suggests limited readiness.
• Perceived effort: RPE 1–3 during warm-up is expected; RPE 5+ is a warning.