Lactate Threshold Testing – The Whole Story
While field tests, like the functional threshold power (FTP) 20 min test or a similar type time trial for runners provides a number that science says closely correlates to the lactate threshold, these tests do not tell us the whole story. Improving power and pace are the outcomes of improving the supporting metabolic systems. But “field” tests do not allow us to measure and monitor these metabolic factors. And while some cycling-specific training systems promise a consistent 2% gain in FTP, this simply is not possible. However, while the power numbers, will not infinitely improve and ultimately have a ceiling, with a well-structured training plan, there is continual improvement sustaining threshold power, more efficiently and with less stress on the systems. A lactate test and resulting curve allow us to understand these improvements, an FTP test does not.
Lactate testing provides a wealth of information to more effectively and efficiently guide the athlete to reach their goals
Sidebar —- there is no doubt that the advent of the power meter has revolutionized training, it is objective and absolute. But I feel many have lost perspective that power is a tool, not a competition in and of itself. Power jargon and terms like TSS have become trendy talk in the group rides. But in my opinion, chasing numbers often overshadows the true objectives of training. The use of power as a definitive target, ensures we are achieving the intended objectives of the specific training zones. But in a training session, like intervals, I suggest only periodically referencing the numbers, versus laser locking on them. In my opinion a training session is most effective when we mentally connect the dots to “why” we are doing a certain workout. For example, during an interval session, I try to visualize a key section of an upcoming race, and glance periodically at the power numbers. But my primary mental focus is on pedaling with efficiency and rhythm under the higher intensity, and mentally locking on to a mantra to power and pedal through the pain. Days when I do intervals, without intention and am simply chasing power numbers and ticking off the time, are far less effective.
Julie collecting blood with a lactate meter
With this loss of perspective on the use of power, power numbers in and of themselves have become the competition. Many riders are highly motivated by abbreviated FTP tests, which yield attractive high FTP values, but typically over-estimate the FTP. In simple terms, threshold is the highest intensity that an individual can hold for one hour. It is the point where lactate production equals lactate clearance (as a result of clearance, buffering and/or metabolizing for energy). However, it is a big ask to have a recreational or master athlete perform a one-hour time trial to determine threshold. When we use these abbreviated protocols, which often result in an over-estimated FTP and consequently over-estimated training zones, the athlete either fails to achieve the prescribed power values of the workouts, and/or is missing essential “blocks” in his/her base of fitness. This athlete is essentially building toward peak performance on a weak foundation, having missed the ability to develop key physiologic and metabolic systems by training with accurate zones.
The lactate curve provides two inflection points – the aerobic threshold and lactate threshold
Lactate testing is equally valuable and insightful for runners as cyclists. In addition to pinpointing the lactate threshold, or where we start transitioning from an aerobic to an anaerobic state, the lactate curve also indicates the top of the pure aerobic zone. With field tests, we use generalized percentages to develop the training zones based on the determined threshold number. But everyone is unique and these percentages may not apply. For example, I recently tested an athlete at the Kaiser Sports Medicine Endurance Lab, who almost exclusively prescribes to high intensity interval training (HIIT), with little to no endurance training. And her lactate curve confirmed this by exhibiting an abbreviated aerobic zone, before the lactate line started to climb. But, she had a well-developed high end fitness. She was building on an inverted pyramid, in other words missing essential elements in her fitness produced by endurance training, i.e. improved mitochondrial density, capillarization and fat oxidation, and reduced lactate production. In her case the general percentages would not apply, and would have over-estimated the extent of her endurance zone.
For runners the test protocol is developed based on the individual runner’s 10 k pace
The lactate curve also helps us understand if the athlete is more aerobically– or anaerobically–inclined. A more aerobically-inclined athlete, who is endowed with more slow twitch muscle fibers, will produce less lactate, and in fact this muscle fiber type will efficiently utilize and combust the lactate for energy. The more anaerobically-inclined athlete with a high percentage of quick twitch muscle fibers will produce greater lactate and will not efficiently reprocess and utilize lactate as energy. As such, we can use the levels of lactate production to better understand an athlete’s natural strengths. With this understanding, we can help guide the athlete to capitalize on his/her natural strengths and pursue disciplines that best play to their genetic gifts.
A lactate test helps us fine-tune and further individualize an athlete’s training program
Measuring lactate production can also, in the presence of other psychological and performance criteria, help confirm over-training. In an “over-trained” state, muscles have a reduced capacity to produce lactate. In my experience, rest is the hardest “sell” to endurance athletes. Many endurance athletes are hard chargers, with a more–is–better mentality and high threshold for training loads and pain. Sometimes, more objective evidence is the only way to convince them a change in course is absolutely required.
While field tests can provide the next best thing, in terms of developing more accurate training zones, they simply do not allow us to understand the whole picture. A lactate curve is rich with information – it equips the athlete with precise individualized data to identify weak links in conditioning; helps the athlete understand his/her natural strengths; determines accurate training zones; and ultimately allows us to further refine and individualize training to help the athlete more efficiently and effectively reach his/her goal.
See you “out there…”
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