Quantifying training intensity distribution in elite endurance athletes: is there evidence for an "optimal" distribution?
Level 4 - case-series / case-control
Prospective observational case series tracking training sessions without a control or comparative intervention
PubMed 16430681 · doi:10.1111/j.1600-0838.2004.00418.x
What was done
Eleven male well-trained junior cross-country skiers underwent treadmill testing to exhaustion to determine ventilatory thresholds (VT1, VT2), VO2max, and maximal heart rate, establishing a three-zone model. Over 32 consecutive days, 384 training sessions (347 endurance, 37 strength) were monitored using continuous heart rate recording and session Rating of Perceived Exertion (RPE). Blood lactate was also measured in a subset of 60 consecutive sessions.
What was found
Across 318 endurance sessions, training intensity distribution showed a polarized pattern: - Heart rate analysis: 75 +/- 3% in zone 1 (<VT1), 8 +/- 3% in zone 2 (VT1-VT2), and 17 +/- 4% in zone 3 (>VT2). - Session RPE: 76 +/- 4% in zone 1, 6 +/- 5% in zone 2, and 18 +/- 7% in zone 3. - Blood lactate (60 sessions): 71% <=2.0 mM, 7% between 2.0 and 4.0 mM, and 22% >4.0 mM (mean = 9.5 +/- 2.8 mM).
Why it matters
This study provides empirical quantification that competitive endurance athletes organize their training in a polarized model, spending ~75% of volume below threshold and 15-20% above, with minimal time at threshold intensity. It also demonstrates strong agreement among heart rate, RPE, and blood lactate monitoring.
Limits
The study is limited by a small sample size of 11 male junior athletes over a single 32-day period. The observational design did not test an intervention or evaluate whether this distribution produces superior performance outcomes compared to other models.
Cited by
- supports The 80/20 training intensity model originated from training logs of elite athletes showing roughly 80% of sessions were at low intensity and 20% at high intensity.