The first type of speedwork we’ll look at is threshold training. In the 1980s, Jack Daniels (the world renown exercise physiologist and running coach – not the whisky guy!) introduced the term ‘cruise intervals’ to runner. These, along with tempo runs have become the mainstay of threshold training.
But what do the terms mean?
Threshold training – during running, the muscles obtain fuel from a process called glycolysis. As a bi-product of this process, lactic acid can be formed. When exercising gently enough, the body is able to utilise this lactic acid to help fuel the running effort. However, once you start running harder, the lactic acid can build at a pace that the body is unable to clear from the muscles. The point where the acid build up is occurring at the maximum rate at which the body can clear and use it is known by various different terms most commonly lactate threshold or anaerobic threshold. Threshold training is training at a pace that is designed to improve the body’s threshold ie to increase the speed at which the lactate rises at a pace which the body is unable to use.
Tempo runs – tempo runs are continuous runs at a pace that is designed to boost your lactate threshold. The effort required is the same as one you would use if racing for an hour. So, if you complete a 10k in 60 minutes, your 10k would be your threshold pace. For the Paul Tergats of this world who run a half marathon in 60 minutes, their half marathon pace would be their threshold pace. For most club runners it will be somewhere between 10k pace and 10 mile pace. Daniels would suggest that ideally a tempo run should be 20 minutes long (with additional warm up and cool down). Other coaches would include longer tempo runs for marathon runners eg Pfitzinger & Douglas include an 11k tempo run in Advanced Marathoning.
Cruise intervals – the aim of cruise intervals is to run a longish interval at threshold pace with a short recovery so that the lactate level remains fairly constant throughout the session. By running cruise intervals, a runner could run for longer periods at threshold pace than during a tempo run. An example would be for a runner whose threshold pace is 6 minute miling, a cruise session could be 4 x 1 mile with 60 seconds rest between each interval. This would give the runner 24 minutes at threshold pace – more than our 20 minute tempo run. Another use for cruise intervals is to throw a couple of mile intervals at threshold pace into a weekly long run.
There is an almost unbreakable link between race pace and lactate threshold. Your 10k pace will be very close to 2.5% above your threshold pace and your half marathon pace will be very close to 2.5% below it. Fortunately, lactate threshold responds well to training and can be improved by most runners. Daniels and most coaches would advocate plenty of tempo runs and cruise intervals to boost it.
But are they right???
Watch this space and train smart!!