Power Duration Curve (PDC)

The Power Duration Curve (PDC) maps your best average power, or maximal mean power (MMP), across different durations. It is a useful way to understand short-power ability, sustained threshold power, and the data behind CP and W' estimates.

What is a Power Duration Curve?

In simple terms, it plots your best efforts on one curve:

• X-axis: duration (from 1 second to hours).
• Y-axis: average power (watts).

Typically, the curve looks hyperbolic:

• Left side (short duration): very high power, representing neuromuscular explosiveness and anaerobic capacity.
• Right side (long duration): power declines and flattens, representing aerobic metabolic capability (often summarized by CP).

Key Components of the Curve

In Trainingload.ai and common sport-science models, the PDC is often described using these key parameters:

1. Maximal instantaneous power (Pmax)

The far-left end (often ~1 second or less) represents the absolute maximum power your neuromuscular system can produce. It depends largely on strength and neural recruitment.

2. Anaerobic work capacity / functional reserve capacity (W')

W′ (“W prime”) represents the total amount of “extra work” you can do above Critical Power (CP).

• When your power exceeds CP, W' begins to deplete.
• When W' is depleted, you generally need to reduce power toward CP or below.
• See: W′

3. Critical Power (CP)

CP is the model threshold that describes the high sustainable side of the curve. In practice, it is limited by fatigue mechanisms and often aligns with hard steady efforts shorter than or around an hour, depending on the athlete and model fit.

• It is the asymptote on the right side of the PDC.
• See: CP

How to interpret your PDC shape

Different curve shapes reveal your “type”:

1. Sprinter-type

• Traits: very high left side (huge Pmax), but the curve drops quickly.
• Strategy: avoid long breakaways; conserve energy in the pack and launch in the final 200 meters.

2. Time trialist-type

• Traits: unremarkable sprint end, but a flatter curve and slower decay on the right.
• Strategy: strong sustained output. Try long breakaways, or use hard pulls to deplete opponents’ anaerobic reserves.

3. All-rounder-type

• Traits: smooth curve without clear strengths or weaknesses.
• Strategy: adaptable tactically, but may lose out in extremes (pure flat sprint or very steep climbs) against specialists.

How Trainingload.ai uses PDC

Trainingload.ai uses the PDC as the evidence layer for CP, W', FTP estimates, and athlete profile review. The curve helps separate different performance questions:

1. Short duration: 5 seconds to 1 minute reflects sprint and anaerobic ability.
2. Middle duration: 3–8 minutes often reflects VO2max-oriented power.
3. Long duration: 20 minutes and beyond is more relevant to threshold and aerobic durability.

PDC quality depends on the data behind it. If you only have easy rides or one 20-minute test, some parts of the curve may be under-tested rather than truly weak.

For a direct model fit, use the fit Critical Power for training load modeling. For a file-based FTP estimate, use the estimate FTP training load from an activity file.

---

Related:

• Critical Power (CP)
• Functional Threshold Power (FTP)
• W' (Anaerobic Work Capacity)