The 80/20 ratio applied to your goal race

The percentages in the "Understanding Training Zones" article are based on endurance training research, particularly the polarized training model (Seiler, 2010) and the 80/20 rule proposed by Stephen Seiler and Erik Tønnessen.

Here's the science behind these distributions and how they would look when training for a certain distance:

1. Marathon & Ultramarathon (80% Zone 1 & 2, 10% Zone 3, 10% Zone 4 & 5)

• Why so much Zone 1 & 2?

  • Long-distance events are primarily aerobic, meaning they rely on oxidative metabolism (Foster et al., 2001).

  • The ability to efficiently use fat for fuel is crucial, and this is best developed in Zone 2 (Brooks & Mercier, 1994).

  • Studies on elite marathoners and ultramarathoners (Seiler, 2010) show they spend 80% or more of their training time in lower-intensity zones.

• Why only 10% high-intensity?

  • Too much time in Zone 3 and above leads to excessive fatigue and a higher risk of overtraining (Midgley et al., 2006).

  • Limited but strategic use of Zone 4 and 5 improves lactate threshold and running economy without causing burnout (Jones & Carter, 2000).

2. Half Marathon (70% Zone 1 & 2, 15% Zone 3, 15% Zone 4 & 5)

• A slightly higher proportion of tempo (Zone 3) and threshold work (Zone 4) is needed to sustain a strong half-marathon pace.

• Threshold training (Zone 4) enhances lactate clearance, which is key for distances requiring sustained efforts above aerobic threshold (Billat, 2001).

• VO2 max intervals (Zone 5) improve overall speed and efficiency, helping runners maintain pace in the latter half of the race.

3. 5K/10K (60% Zone 1 & 2, 20% Zone 3, 20% Zone 4 & 5)

• Higher-intensity training is emphasized because shorter races require greater anaerobic contribution.

• Zone 4 & 5 training improves running economy and neuromuscular adaptations, essential for shorter races (Midgley et al., 2006).

• A higher percentage of tempo running (Zone 3) helps runners sustain race pace longer before fatigue sets in.

• A strength training routine is very important, especially early in the season, as this ratio is very speed focused and will cause a lot of stress on the body.

Why Follow These Guidelines?

• Endurance adaptations happen primarily in Zone 1 & 2.

• Too much Zone 3 training leads to stagnation—it's neither easy enough for recovery nor hard enough for significant stimulus (Seiler, 2010).

• Zone 4 & 5 improve performance but must be used sparingly to prevent overtraining (Midgley et al., 2006).