Cardio equipment at the gym, a bike computer, or a top-end GPS fitness computer shows your speed, power, or calories per hour, but no clear indication of how your body is handling the work. How aerobic or anaerobic are you? Is your aerobic fitness increasing, or are you compensating with anaerobic energy? Is it time to increase intensity?

You're working hard; but are you working smart?

Heart rate formula's don't help because our aerobic and anaerobic capacity change as our fitness increases and decreases; heart rate formula's assume fitness never changes and is the same for everyone, a major flaw. In fact heart formulas were never intended to set exercise intensity; the age-heart rate relationship was simply a population statistical average. A fit person can increase heart rate during exercise by as much as 100 bpm above resting with no significant increase in lactate while an untrained person will have lactate values skyrocket at 50 bpm above resting.

Heart rate values assessed with lactate values validate the correct heart rate values, which change as a persons fitness changes. There are competitive season and off season changes in how heart rate correlates with lactate threshold, recovery heart rate, and intensive interval values. Are you using the same training heart rate values all year?

Lactate testing provides a no-guess-work clinically accurate indication of how aerobic or anaerobic we are (we're always a little of both).

We can get good data from a laboratory VO2 Max test as well, and I do recommend VO2 testing for athletes and fitness enthusiast, the advantage of lactate testing is the very low cost and do it anywhere ease of use.

Your muscles always produce lactate, even at rest. Resting blood lactate values are about 0.8 - 1.5 mmol/L. Lactate increases incrementally with exercise intensity. When you achieve a certain intensity where lactate increases exponentially you are crossing the lactate threshold ("LT"), which on average occurs at around 4.0 mmol/L of lactate. See lactate curve graph below.

Fatigue onset is rapid above the LT, but efforts just below the LT can be sustained for hours by well trained athletes. To increase how long you can maintain your highest output in endurance events, you must increase your power at LT and strive to raise your LT to your highest genetic potential.


Lactate testing is used to evaluate fitness, changes in fitness, and provides the correct heart rate zones for an individual to exercises at.

Lactate testing is beneficial for everyone whether just getting started with fitness or trying to gain the edge in elite athlete development.

Training too hard too soon is the most common exercise mistake. It's a waste of time to hammer away at diminishing returns with transient improvement, soreness, and injury.

A proper fitness assessment starts you off right and prevents overdoing it.


Lactate analyzers don't test for lactic acid. The machines measure the presence of lactate dehydrogenase, an enzyme involved in complex muscle metabolism, converting pyruvate to lactate.

Blood lactate levels reflect to what degree steady state exercise is aerobic and anaerobic (there is always a mix of the two), and more importantly; changes in aerobic/ anaerobic metabolism that occur from training.

Above is a classic lactate curve comparison depicting blood lactate levels during a test where exercise intensity is increased in fixed stages. Comparing repeated tests as fitness increases will show a lower lactate for a given intensity. This is a result of both producing less lactate and clearing lactate faster at any given intensity due to adaptations primarily in the muscles mitochondria, capillaries, lactate transporters, and the liver. Heart rate will generally decrease for a given intensity as you become more fit, but using the same heart rate zones as your fitness increases will sell you short as heart rate will not account for the changes in metabolism that are indicated with lactate testing.

An untrained persons LT is between 50% and 60% percent of their max heart rate, and in a trained individual is between 70% and 85% of max heart rate. The same person at the same age can have very different lactate thresholds, depending on how "trained" they are. Heart rate formulas don't account for this variable, and can't monitor the gradual increase in LT over months or years of exercise. If you're just starting exercise, 60% of your max heart rate may be too intensive, if you're already fairly fit 75% - 80% might not be intensive enough. How could you know where you're at without measuring?

More power at LT and shifting your LT to a higher percentage of your maximum output is the most important factor for increasing performance whether you are an endurance athlete or simply looking to get more fit. If you can't measure your LT, you'll waist a lot of exercise time trying to "ballpark" it. Too much training at or above the LT results in overtraining, training too far below the LT will not improve LT performance.

Training too much at either end of the exercise intensity continuum results in the same thing: lot's of exercise but poor or inconsistent results. Lactate testing allows you to get the most out of your exercise time.

Lactate testing is used all over the world by researchers and athletic coaches. It is currently the gold standard for determining exercise intensity zones and a significant tool for determining whether or not training is producing the desired physiological effect.

Those starting an exercise program will experience a greater degree of change in lactate levels at a given intensity than those who are well trained, requiring more frequent updates to heart rate zones. So contrary to popular belief, frequent lactate sampling is just as important for beginners as it is for athletes.

Lactate testing is not "new". Physiologists have been measuring lactate in exercising humans for decades, and the lactate molecule was first isolated in 1789. The advent of portable analyzers has made lactate testing more accessible, so more people are using it now compared to 10 years ago.

"People have been getting fitness results without measuring lactate, so what's the point?" It's true great champions were developed without lactate testing. Now great champions are developed with lactate testing, with less wasted training time.

Lactate testing allows for a more accurate assessment, and therefore more accurate prescription of exercise.

Lactate myths

The graph below- taken from this Rhino Fitness article, shows how lactate and heart rate levels change as a person becomes more fit. A heart rate level that represents a high intensity when unfit, will represent a low intensity after a person increases their fitness. At a certain level of fitness development these adaptations begin to level out, but a person is still able to increase how fast they can go for the same heart rate and lactate. Without accurate measuring and the expertise to interpret these measurements, no person could accurately "guess" at what exact point an individuals exercise plan needs amending. But guessing is the only option if one does not measure.

The data above is from a 45 year old male who wanted to complete a marathon for the first time. We started easy and gradually increased intensity according to lactate testing results. In order to keep up with this persons increase in fitness, intensity (calories per hour) and heart rate had to be frequently amended in the early stages, but less frequently in later stages. Look at the large change in energy expenditure and comparatively smaller change in heart rate over the first few months. After one year of regular exercise this person could burn off 48% more calories in hour than when they started, and have it feel easier!

This person can easily exercise at 1000 calories per hour - nearly 100% harder than when they started. "Training plans" that have arbitrary increases in intensity such 10% increase every week don't require expertise, time, or measuring to make. Just hand out the same program to you that was handed out to the last person.

The relationship of heart rate and lactate change as you get more fit. So exercising at the same heart rate does not mean you are training at the same aerobic or anaerobic level. Ongoing lactate testing lets you know if you are keeping the fitness, becoming fatigued, or losing the fitness, more precisely than with heart rate measurements alone.

The above graph let's us beware that the statistical average of lactate threshold occurring at 4.0 mmol/L is just that; an average. To get real value from lactate testing each persons individual lactate threshold should be determined.

This individuals lactate threshold occurs at a heart rate of 155 and lactate of 5.0 mmol/l. Note the exponential increase in lactate after this point. Note at the low end a large change in heart rate corresponds in a small change in lactate, and as the lactate threshold is approached and surpassed, a small change in heart rate corresponds in a large change in lactate. These values correlate well will a shift from carbohydrates and fats for fuel to carbohydrates only; from predominantly aerobic to predominantly anaerobic; from low power output to high power output; and from time to fatigue being long to time to fatigue being short.

Lactate values provide invaluable information to the coach and to the person training. You can get fit without lactate testing, no doubt about it. Getting there is far more efficient with lactate testing, saving time, preventing under and overtraining, and providing more fact based evidence from which to make informed decisions from versus simply training a lot and wondering which part of your training is causing a training effect and what part is "junk training".

Contact Cris LaBossiere to inquire about lactate threshold testing and other lactate testing services





You can buy the Lactate Pro on line at Woodcock Cycle, or visit them in person at 433 St Mary's Rd. in Winnipeg, or call at 204 253 5896 toll free 866 211 5795.

- Cris LaBossiere

Who uses lactate testing? Every exercise lab in the world, almost all provincial, state, and national sports organizations including swimming, running, triathlon, rowing, cycling, cross country skiing, hockey.