The Science Behind Mixing Training Intensities

Further, in the last 110 days before the games the pursuit squad had only six days of high-intensity interval training on the track. They won gold.

Billat, et al in 2001 found that a group of French and Portuguese marathon runners spent approximately 78 percent of their training time in Zone 1, 4 percent at marathon pace (correlated to Zone 2), and 18 percent in Zone 3. Similarly Billat, et al found, in 2003, that Kenyan 5K and 10K runners spent approximately 85 percent of their training kilometers at levels below lactate threshold (LT1).

Gullich, et al found that 95 percent of the training undertaken by world-class junior rowers in the 37 weeks before the national championships was at 2-mMol or less blood lactate concentration.

When taken in total, Seiler and Tønnessen advocate for an approximate intensity mix of 80:20 for low- and high-intensity training. They note that increases in training volume correlate well with increases in the physiological variables of performance.

The Recreational Athlete

So what does all this mean to the rest of us? The study did reference the training programs of recreational athlete: those who train six to 12 hours per week. In a 2001 study, Foster, et al found that most recreational athletes tend to train too hard on easy days and not hard enough on hard days.

Over time this puts the athlete into what Seiler and Tønnessen describe as the "black hole" of training intensity, where nearly every workout is completed at the same threshold intensity.

This was shown in a study by Esteve-Lanao, where athletes were prescribed a highly polarized training load of approximately 77/3/20 percent at zones 1/2/3 respectively, yet based on heart rate recording their actual training load was 65/21/14 percent for zones 1/2/3 respectively. In short, they found that athletes with limited time have a hard time following a polarization protocol.

Interestingly, they did not offer any additional insight as to the effects of these "black hole" training regimes beyond the above mentioned Esteve-Lanao study that showed an improvement in 10K times for athletes following a polarization protocol during an 11-week study.


Low-intensity training has long been the standard for endurance sports. Upon reviewing nearly 100 published articles and case studies, Seiler and Tønnessen postulated that elite-level athletes tend to progress and perform best under a program that emphasizes a high volume of low-intensity exercise (<2-mMol blood lactate concentration) mixed with focused high-intensity efforts at and above one's lactate threshold (>4-mMol).

Their belief is that this review and approach repudiates the current trend towards high intensity and steady state training in lieu of building a traditional aerobic base.

Next time, we'll look at the other side of the equation—the efficacy and effectiveness of a program built on a diet of steady-state and threshold-level workouts for those with less time to train.

Seiler, Stephen, and Tønnessen, Epsen. Perspectives in Training: Intervals, Thresholds, and Long Slow Distance. The Role of Intensity and Duration in Endurance Training. online journal, 13, 32-53, 2009.

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