Data That Matters, Part One

posted Feb 28, 2010, 5:28 PM by Donald Vescio   [ updated Dec 30, 2011, 10:04 AM ]
There is a tremendous range of data available for today’s multisport athlete and it can be daunting to figure out what values are of most use in improving performance.  VO2, lactate threshold, anaerobic threshold, heart rate zones, critical power, normalized power, pace--what do these terms mean, what are their predictive value, and how should we use them?   

What follows is the first of a two-part series that will help you make sense of data collection and analysis for performance athletes.  

Data That’s Interesting, But Not Useful 
There is a lot of data available to athletes that are interesting, but not necessarily useful in improving personal performance.  For endurance athletes, the “gold standard” data point is one’s VO2 max, which is a measure of the body’s ability to process oxygen during exercise.  A high VO2 max value normally is associated with superior endurance performance; world class cyclists, runners, and swimmers generally will have VO2 max values in excess of 80 ml/kg/min.  (To put this in perspective, Greg Lemond reportedly had a VO2 value of 92.5.) 

The problem with VO2 max, however, is that it is largely genetically determined; in other words, a trained individual’s VO2 value will not vary significantly throughout the training year.  As an indicator of athletic potential, VO2 data has some predicative value, but it has limited use as a means of establishing workouts and tracking performance.  Values like max heart rate also function like VO2—while interesting, it has no real utility for day-to-day training and performance assessment. 

Data That’s Interesting and Useful 
Useful data is data that can be collected easily and consistently and has value for both assessing past performance and predicting future activity.  A good example of useful data is one’s lactate threshold, which is a measure of when lactate begins to accumulate in the body during exercise.  As lactate accumulates in the body, muscle contraction is impacted, power output decreases, perceived effort increases, and discomfort is experienced.  An easy way to understand lactate threshold is the highest level of exertion one can sustained for a period of approximately 30 minutes. 

Unlike VO2, one’s lactate threshold does respond to training.  As fitness increases through a structured program of intervals and rides near threshold, one is able to raise the point at which lactate accumulates, which means that the same athlete will be able to exercise longer and at a higher intensity.  Lactate threshold can be measured in a number of ways, including ramp tests on a treadmill or ergometer, or through blood sampling by an experienced exercise physiologist or other trained professional.  (Interestingly, multisport athletes should establish their lactate thresholds for each event, as it does assume a sport-specific component.) 

Putting Data in Context 
Imagine the profiles of two hypothetical athletes: Gabriella and Chloe.  Gabriella is a genetically gifted triathlete who has a high—82 ml/kg/min—VO2; unfortunately, Gabriella does not train on a regular basis, so her lactate threshold is relatively low.  Chloe does not have similar genetic potential—her VO2 is 70 ml/kg/min—but she is conscientious in her training and has a very high lactate threshold.  Assuming that Gabriella and Chloe are approximately the same age, height, and weight, chances are excellent that Chloe will beat Gabriella when racing side-by-side. 

When collecting data, it is important to recognize that one cannot rely on a single type of data when developing an effective training program.  A cyclist, for instance, has perhaps the greatest opportunity to collect all kinds of data: speed, distance, heart rate, power, etc.  Focusing on heart rate or perceived effort alone does not necessarily mean that one will be exercising at an optimal level (for instance,  a cyclist could spinning at a very high rpm in a very small gear, which would result in a high heart rate, but low power output and low average speed), similarly, focusing on power alone does not measure the impact that the effort has on one’s effort (it is possible that an individual may experience vastly different heart rates/perceived efforts for intervals at the same power).  The goal in data collection and use is that values should be collected that reflect both bodily stress (e.g., lactate threshold) and actual performance (e.g., average power) both for the duration of specific exercise sessions and for extended periods of time. 

What’s Next? 
This installment only has touched the very basics of data collection and analysis.  The next installment will focus on tracking specific types of data over time as a way to assess overall training.

Go to part two