Tempo Runs

A tempo run, sometimes called a threshold run, is a common part of many training programs as coaches believe it is an effective way of improving lactate clearance. However, the science indicates that tempo paced runs should be avoided in favor of other paces. Tempo pace represents the no man's land between Long Slow Distance and High Intensity Interval Training. They can improve performance in the untrained, but not as well as other types of training. For highly trained runners Tempo Runs may actually be counterproductive.

1 What is a Tempo Run?

A Tempo Run intended to be run at or near the pace corresponding to the Lactate Threshold. Lactate Threshold can be thought of as the transition from mostly aerobic to mostly anaerobic metabolism. In well trained athletes, paces below the Lactate Threshold can be kept up for prolonged periods (several hours), where paces about the Lactate Threshold typically cannot be maintained for more than an hour.

2 The Tempo Myth

There is a prevalent myth that Tempo runs are an important part of a training program. The idea is that running at Lactate Threshold pace improves Lactate clearance and thus improves performance.

• Jack Daniels, author of Jack Daniels Running Formula says "Threshold, or T-pace, running is one of the most productive types of training that distance runners can do".
• Hal Higdon in "Marathon The Ultimate Training Guide" says "Exercise scientists now tell us that doing tempo runs is the most efficient way to raise your lactate threshold - that is, your ability to run at a fast pace without accumulating lactic acid in the bloodstream".
• Matt Fitzgerald in his book "Run Faster" says "Threshold training is a major part of every running coach's training system", and that "enable runners to sustain faster and faster running paces
• "Threshold runs … stimulate aerobic-system adaptations and other physiological changes that enable runners to sustain faster and faster running paces for longer and longer stretches of time"

3 The Science of Tempo Runs

The idea that training at threshold intensity is particularly effective has no evidence.

• Tempo runs can improve performance in untrained subjects. However these studies did not compare how effective tempo runs are over other forms of training.
• In recreational 10K runners, there is not as much improvement from training at Lactate Threshold as from polarized (low/high) training.
• Training at Tempo paces is ineffective for trained athletes, and may even be counterproductive.
• Training at lower intensity (blood lactate < 2 mmol/l) is more effective at improving performance at the Lactate Threshold than training at the Lactate Threshold (3-6 mmol/l).
• A 2007 randomly assigned 12 sub-elite 5K & cross country runners to one of two training programs. The Z1 program had 80% LSD, 10% Tempo, and 10% HIIT, whereas the Z2 program had 65% LSD, 25% Tempo, and 10% HIIT. The Z1 group that did less time at Tempo pace improved their race performance more than the Z2 group. (Their simulated 10K times improved 35 seconds more, 157 second improvement rather than 121 second improvement.)
• A 2009 review of the science of training intensity noted that recreational runners typically fall into a "black hole" of too much Lactate Threshold running. They noted "Training intended to be longer and slower becomes too fast and shorter in duration, and interval training fails to reach the desired intensity. The result is that most training sessions end up being performed at the same threshold intensity."
• The performance of elite 5k/10K runners is related to total time spend in low intensity training, not higher intensities.
• Polarized training has been shown to be more effective than high volume/low intensity, threshold/tempo, or High Intensity Interval Training. The polarized training used two High Intensity Interval Training and two long (150-240 minute) low intensity sessions.
• It has been observed that elite athletes exercise 80% of the time at low intensity (blood lactate < 2 mmol/l) and 20% of the time at Lactate Threshold or High Intensity Interval Training. (Sadly this study did not have any breakdown between Lactate Threshold or High Intensity Interval Training.)
• A 1991 study of elite runners found that they spent little of their time training at lactate threshold, something that was then considered sub-optimal. Note that this is in spite of the prevalent belief of coaches in the value of Lactate Threshold training.
• A study of rowers before the world championship found they spent the majority of their time in the rowing equivalent of Long Slow Distance (<2 mmol/l) with 4-10% of High Intensity Interval Training (6-12 mmol/l) and no training at Lactate Threshold.
• An analysis of the training of elite junior cross-country skiers found they spent 75% of their time at low intensity, 17% at high intensity, and only 8% around Lactate Threshold. The study concluded "It appears that elite endurance athletes train surprisingly little at the lactate threshold intensity."
• There is anecdotal evidence of two world class athletes that improved their performance after de-emphasizing threshold training.

4 Why Are Tempo Runs Ineffective?

The science does not give us a clear answer as to why Tempo runs are relatively ineffective. My personal guess is that Tempo pace is still mostly aerobic, so it has similar benefits to running at a slow pace, but it can't be kept up so long. High Intensity Interval Training probably has dramatically different benefits to Tempo or Long Slow Distance. There is a common claim that Tempo runs have mental benefits, but the scientific evidence does not bear that out in real world performance improvements.