Improving aerobic capacity, improving lactate threshold and improving economy are three ways to improve cycling performance. This article focuses on improving lactate threshold as a means of improving cycling performance, which essentially means going faster at the same perceived rate of exertion.
Lactate threshold (LT) is often referred to as aerobic threshold (AT), ventilatory threshold (VT) or functional threshold power (FTP). Lactate threshold is the maximum exertion level an athlete can sustain for approximately one hour. Lactate threshold is the level at which an athlete begins to “redline” – go above that level for too long, and the athlete explodes in a lactic bath; race below that level, and our cyclist leaves something on the table.
Physiologically, lactate threshold is the level of exercise intensity at which lactate begins to accumulate rapidly in the blood. As intensity increases, carbohydrate use for energy production increases rapidly, and lactic acid begins to rise as a byproduct of burning carbohydrate as fuel. With the rise in lactic acid, lactate levels increase as a buffer against hydrogen ions that begin to accumulate in the blood.
Contrary to popular belief, lactate is not the problem for the athlete seeking to improve cycling performance. Increased lactate presence in the blood is more of an indicator of threshold as the hydrogen ions begin to accumulate. Hydrogen is the real culprit. Lactate seeks to buffer the muscles that are now operating in an increasingly acidic environment. Hard, frequent breathing, combined with lactate buffering agents, is the body’s attempt to release hydrogen ions from the blood and retain ph balance.
Thus, measuring lactate presence in the blood is a convenient way of measuring hydrogen. During a laboratory lactate threshold test, frequent blood draws are taken as the exercise intensity is systematically increased. Lactate threshold in most athletes occurs at measurement of 4mMol. (Lance Armstrong’s LT was reportedly measured at 6mMol). Lactate levels tend to rise gradually to this point, after which additional increases in exercise intensity result in a hyperbolic increase towards 8mMol or higher – the proverbial lactic bath – which is not sustainable for long.
Whereas aerobic threshold or VO2 max or aerobic capacity is largely a genetic gift that can be optimized through training, lactate threshold is highly trainable. The more fit you are, the longer you can sustain an effort at lactate threshold. Lactate threshold is often expressed as a percentage of VO2 max, and 80-85% of VO2 max is a common lactate threshold level for fit athletes.
So, in our earlier example of our cyclist with a VO2 max measured at 330 watts on the bike, that athlete is seeking to improve lactate threshold to the point where 264-280 watts can be sustained for a one-hour period. Given that 10 watts often translates into 1 mile per hour on a time trial bike, moving threshold closer to 85% of VO2 max is the goal for our cyclist.
How to Raise Lactate Threshold as a Percent of VO2 Max
According to Joe Friel, there are two ways to improve lactate threshold: train your body to remove Hydrogen (H+) more quickly, and/or train your body to become better at tolerating H+.
As with training the VO2 max, a cyclist can increase the volume of training at or above 50% of VO2 max (above 165 watts in our example). This approach used in isolation will take a long time and may not ultimately result in achieving lactate threshold potential watts.
Another approach is to train at moderately high intensity over long intervals with a short recovery. For our cyclist with a VO2 max of 330 watts, beginning an interval training program at 75% of VO2 max, or 250 watts, is effective way to begin moving the lactate threshold higher. So, in the early weeks of a build program, our cyclist might begin with 2 intervals of 10 minutes duration at 250 watts with 5 minutes recovery in between. Over an 8-12 week period of time, the frequency of intervals, the rate of exercise intensity measured in watts and/or the duration of intervals would be increased in order to achieve lactate threshold intensity.
A training program that includes increasing amounts of time at endurance pace (165-190 watts) to build aerobic endurance and a progressive interval training program with intervals just below or at lactate threshold (264-289 watts) is an effective way to improve lactate threshold. Improve lactate threshold = improve cycling performance = go faster on the bike.