Triathletes: Exploring Lactate Threshold Testing

"Can you do three more minutes?" I winced my way through the end of a 30-minute blood lactate threshold cycling test inside a fluorescent-lit lab. The strain in my legs and pounding heartbeat made the 10 tiny pin pricks on my fingers feel entirely inconsequential. Coach Gareth Thomas, designer and operator of the Los Angeles-based Trio sports science and training center, supervised my discomfort with calm detachment. Like Count Rugen as he tortured Wesley in "The Princess Bride."

I grunted something incoherent, so Thomas increased resistance on the CompuTrainer and I pedaled ever harder. Not even a minute later, as my cadence dropped below Thomas' pre-determined baseline, the test was mercifully over.

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I wanted to explore the potential benefits of lab-based lactate threshold testing in my never-ending personal quest for better training and racing data. I also sought a reason why my wattage on the bike had been consistently lower for the past several weeks than my targeted functional threshold power (FTP) goals. What I learned changed my training habits, but not in the way I expected.

Understanding your lactate threshold and VO2 max can help you make smarter training, nutrition, pacing and racing decisions. For the uninitiated, peak VO2 max measures the size of your proverbial racing engine. That's largely based on genetics. As part of a VO2 max test though, Thomas will see how much fat and carbohydrate you burn and when you stop burning it, along with the intensity at which you stop burning fat. The latter is referred to as anaerobic threshold. Knowing how you process carbohydrate and fat will enable you to better create a nutrition plan to sustain your desired race pace. And with better fueling comes increased performance—a supercharged engine.

A lactate threshold (LT) test measures aerobic efficiency and stability. Thomas notes that scientists are not quite sure exactly the depth of lactate's role in the body but he said it's a great marker for efficiency. In general, low levels of lactate are the sign of an efficient aerobic system. The LT test also measures steady-state threshold, which is the last intensity where lactate concentrations stay the same as time progresses.

"Training is about becoming a complete athlete, maximizing potential in all areas so that whatever engine you own can perform at its highest level," Thomas said. "To me, the lab is the number-one place to monitor, measure and access where you are at, so that you can play your way to optimal performance through correctly prescribed training."

More: How to Control Your Breath in Training

Lab time costs money though. Provided you have a power meter and a heart rate monitor, the most common way to determine LT and Vo2 max zones is to perform a 20-minute or one hour field test for cycling or a 30-minute run test. These sessions will closely approximate your training zones. A blood-based test will more precisely confirm them, but at a higher price. Each Trio lab session costs $195, and Thomas recommends testing every 9 to 12 weeks to measure progress. He added that cycling data shouldn't be used to establish running zones and vice versa, so that's twice the fees to consider.

Two renowned coaches I connected with, Siri Lindley and Joe Friel, each acknowledged the benefits of lab lactate threshold testing but agreed that the costs were an issue. One of Lindley's athletes actually worked with Thomas in the past and while the experience was helpful, price was a factor. Lindley, based in Boulder now, hasn't been able to find a lab near her to conduct similar testing at an affordable price. "We don't depend on testing like that so (I) didn't push to find someone to do it," she said. When Friel was more active coaching athletes, he'd have them test in the lab once a year during the base period of their season while adding regular field tests every 3 to 6 weeks. "Heart rate remains fairly constant over the course of the season but power and pace can (and should) change dramatically," Friel explained. "If the various factors (weather, food, course, etc.) are controlled then this is more like a 'standardized' race and gave us real-life data that could be applied to training and racing. It's also 'free' so we can repeat it as often as needed."

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The benefit gained from my lab experience is arguably priceless though. For as long as I've known my coach, he's chided me on occasion for training harder than I need to. Something about "extra credit" not always applying to training intensity. (But it sure is good for Strava trophies!) This unfortunate truth manifested itself in my lab results. While my lab-tested VO2max was on the high side (close to 13 mmol), efficiency apparently is not my strong suit. I'm good at suffering, in other words. The steady-state threshold data, the power one can sustain for an hour, yielded borderline suboptimal performance levels. Sometimes it's easy to ignore what someone is telling you—even if it's that coach you're paying. Ignoring someone when they show you scientifically verifiable data is a lot harder.

Thomas suggested a training regimen heavily focused on improving aerobic and lactate threshold zones, which would feel easy to me based on where I had been training. While my coach was planning to prescribe the same program, my time with Thomas convinced me to simply trust and follow said plan more than I might have on my own.

More: Role of Rest in the Offseason

Four weeks after visiting Trio, I conducted a one hour FTP field test. While it may have been a fluke, my steady-state threshold was dramatically higher than the numbers Thomas had set. A near 30-watt difference. However, all my "improvement" did was reset my FTP to a few watts north of where it was prior to the Trio lab testing. Why? Thomas said it's only possible to judge metabolic progress in a like-for-like situation, so I'd have to revisit the lab to confirm real progress. He added that age groupers with less "metabolic talent" and conditioning should think of steady-state threshold as between 75 to 90 percent of FTP. "In a TT effort over 60 minutes, you will for sure be able to hold higher than SST," Thomas said. "So perhaps you are fitter, perhaps the same. They are different measures in reality."

If money were no issue I'd revisit the lab. As it stands, Thomas' analysis would adequately explain the watts displayed in the field test as it pertains to the lab-prescribed SST—gaining a few watts along the way possibly thanks to my Ironman Arizona build phase. I'd recommend lab-based performance testing to anyone as a way to further validate field testing. In the future, I may employ lab testing in the weeks leading up to an A-race to finalize appropriate power and running zones. In the meantime, I'll simply do a better job following my coach's training plan—something he might think as almost...inconceivable.

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LAVA Magazine

Founded in 2010 and named after the iconic volcanic rock fields found at the Ironman World Championship in Hawaii, LAVA Magazine is the world's premier triathlon magazine. Along with the magazine's stunning photography and design, every issue is full of the newest gear debuts and reviews, training advice from the world's best coaches, and in-depth athlete profiles. Go to Lavamagazine.com for up-to-the-minute training, racing and triathlon news, and follow them at @LavaMagazine.
Founded in 2010 and named after the iconic volcanic rock fields found at the Ironman World Championship in Hawaii, LAVA Magazine is the world's premier triathlon magazine. Along with the magazine's stunning photography and design, every issue is full of the newest gear debuts and reviews, training advice from the world's best coaches, and in-depth athlete profiles. Go to Lavamagazine.com for up-to-the-minute training, racing and triathlon news, and follow them at @LavaMagazine.

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