Ultrafit: Fitness in the blood

A vein in my forehead is about to burst. Sweat streams off my nose. I'm on a stationary bike, hooked to cords and monitors, a hamster on a wheel, legs spinning, lungs gasping, heart-rate racing to 168 beats per minute -- dit-dit-dit-dit-dit-dit-dit -- and climbing higher still.

"Come on, let's hit 170!" shouts Ben Popp, founder of Endurance Athlete, a St. Paul fitness company.

My fingertip is bloody, perforated already with a half-dozen pricks. My head is woozy. Then the three-minute session ends.

"OK, give me that finger," says Popp, grabbing my wrist, a medical needle in hand.

Popp is searching for my blood lactate threshold, a point where lactic acid floods muscle cells too fast for the body to metabolize the excess. This threshold is where athletes "feel the burn," a physiological parameter at which speed, power and efficiency start to suffer under the pain of anaerobic stress.

Professional athletes, notably Nordic skiers and endurance-sports competitors, have sought blood lactate tests for more than a decade. Alongside fitness identifiers such as body mass index, VO2 max (aerobic capacity), heart rate and body composition tests, a blood lactate profile helps prescribe workout regimens individualized for the physiological makeup and fitness level of each athlete on a roster.

Indeed, blood lactate readings can distill the efficiency of exercise to a cellular level, providing a peek at the inner workings of millions of muscle cells, where oxygen, enzymes, glycogen, lactic acid and other infinitesimals mix to pound out movement and power. Trainers and coaches take test results and apply them to heart-rate-based workouts structured for maximum physical efficiency.

"It's about training smarter, not harder," said Popp, a former semi-pro skier who coached college athletes for five seasons before founding Endurance Athlete in 2001. "The goal with any workout should be to do the minimal amount of work possible to elicit the physiological response that you need to make a difference."

With such claims, blood lactate tests are just now entering the mainstream fitness vernacular. Popp says everyday exercisers, recreational athletes and dieters can benefit from the precise fitness plans generated by a lactate profile.

"People who work 50 or 60 hours a week and have just a few hours for fitness can increase their productivity," Popp added.

Piotr Bednarski, founder of the personal-training company Go! Training in Minneapolis, said lactate tests help athletes to ensure that they are not overdoing it. "Some citizen athletes train too hard, which is detrimental," Bednarski said. "I can monitor somewhat scientifically when people need to cut back, or when performance is suffering."

At the pro level, Bednarski offered Caitlin Compton, a 27-year-old U.S. Biathlon Team skier, as example: "Compton never got sick, never showed signs of stress," Bednarski said. "But by analyzing her lactate level I could see when she was overworked and in need of a break from training."

Just one piece of the puzzle

Handheld blood monitors now sell for $250 or less, putting lactate testing in the realm of the common exerciser. But a lactate profile is just one piece of the fitness puzzle, Bednarski said. As with any such test, a person's unique anatomical factors and life circumstance are weighed against the cold numbers.

"A lactate profile is simply a physiological descriptor, like height and weight," said George Brooks, an exercise physiologist, professor of integrative biology at the University of California, Berkeley, and an expert in the field since the 1970s. "There's no silver-bullet test. You do a dietary assessment, body composition, max heart rate and lactate -- it's all part of an overall look at the athlete."

Dr. Shannon Sovndal, founder of Thrive HFM, a training company for athletes in Boulder, Colo., administers blood-based tests to only 20 percent of his clients. He said there is a cachet developing around knowing your lactate level.

"For some recreational athletes it's another bell or whistle," he said.

Sovndal prefers to measure physical output with a power meter on a bike and with heart rate checks in the field. "The [blood analysis] lab tests are useful for the elite athletes who follow a precise training plan," he said.

Other coaches apply the test more liberally. Reid Lutter, program director for the St. Paul-based Minnesota Valley Ski Team, said members as young as 18 undergo frequent lactate tests. "When these kids are training 500 or 600 hours a year, we want to make sure they are making the best use of their time," he said. "Lactate levels are one indicator."

For Chad Giese, a former pro skier from St. Paul who's long promoted training based on lactate levels, blood readings dictated his monthly, weekly or even daily interval workout regimens. Giese, 31, sometimes trained with a lactate monitor in his water-bottle belt. He'd ski a lap or do an interval, then stop to prick a finger. "It was an instant picture that let me train at my most optimal level," he said.

'A generally fit guy'

My test with Endurance Athlete -- a $200 procedure performed over two hours on a Thursday evening -- established a framework for Popp to draw up a personal fitness plan. He pushed me at six increasingly difficult levels on a bike and then a treadmill, pricking my finger to take blood after each session.

From there, Popp charted my lactate levels alongside my heart rate. A graph slowly began to develop, revealing a profile of where my cells began to flood with excess lactate.

Popp identified my lactic threshold as corresponding with a heart rate intensity of about 154 beats per minute. He noted a dead zone around 140 to 147 beats per minute where training for me is highly inefficient.

I left with a general idea of my physical shape. Two days later, Popp e-mailed me a personalized fitness plan:

"Based on our tests, you are a generally fit guy," the plan's introduction read. "You are slow compared to a bike racer, but you aren't a bike racer. You are slow compared to a 5k runner, but you aren't a 5k runner. You are fit for what you do -- ultras, orienteering, etc. With some guided training and planning you will see great improvements in your competitive results."

Sounded all good to me.

Stephen Regenold is a Twin Cities writer and author of a syndicated column, www.thegearjunkie.com.