Welcome to the Cruise (Intervals)

This week, it appears that patience and its virtues have begun to reward me:

I finally managed to get more than 30 miles, a mix of road and treadmill running. More importantly, I'm not limping or walking like a person two decades my senior.

This means I can begin to train toward a couple of 5,000-meter road races. (Sure, I did that one on Thanksgiving Day, but it was more like three one-mile repeats and a 187-meter sprint to keep from looking too slow for the photographers...that one doesn't count.)

So, I decided the third day of each three-day run cycle would be my "speed" day, as long as it didn't occur on a Sunday, which is my "sorta-long" day. To see whether my body was really prepared to handle shorter, but more-intense efforts, I tossed a few 400-meter, kilometer, or mile repeats on at the end of my 5-mile treadmill runs. Those were fun, but the most fun workout so far is the one I did last Friday. For lack of a better term, I'll call it a "progressive tempo" run; two one-mile repeats at long run pace to warm up, followed by 20 minutes of slow acceleration from long run pace up to where my heart rate was just below 160 beats per minute.

Dr. Jack Daniels' and Jimmy Gilbert's research of distance runners of all ability levels back in the late 1970s spawned an abundance of pace calculators and charts in print and on the world wide web; utilized by many running coaches to guide their own training intensities. The charts enable runners to take the performance from race distances as short as 1500 meters or as long as a marathon and determine the maximum amount of oxygen they use in an activity, measured in liters per kilogram of body weight. That ballpark measure of physical potentiality (The potential for physical performance is definitely NOT the same as the ability, as many coaches will tell you.) aligns to, in many cases, a second chart of pace ranges to focus on specific training benefits. Daniels, in his Running Formula, recommends a person who starts back into a race training regimen (like me) to work to raise the lactate threshold, then to improve the VO2 max, and finally, to improve running economics and speed.

In Running Formula, Daniels states that a runner's lactate threshold - the measure of exercise intensity above which more lactate is produced than can be utilized for fuel - is improved by training runs at what he calls "T"-pace. These training runs can be "cruise intervals" of several minutes in duration - between a kilometer and a mile in distance - with very brief resting periods (which, frankly, I was already doing as part of my training), all the way up to sustained runs of a "comfortably-hard" nature of an hour. The tempo workout is one where, as Daniels says, going too fast is not as good as running the correct pace for the workout. Go either too high or too low and you're running what he calls "quality junk" mileage.

Tempo runs are a good reason to own and use a GPS (or accelerometer) -enabled training watch, or at least a running watch and a course with known distance splits. In the case of road or running path courses, I like one with scenery I can enjoy, not so much to take my mind off the discomfort, but to reinforce a comfortable state where I'm still working hard (a tree-lined, smooth out-and-back from the CBD through the Lower Garden District to Audubon Park is one of my favorites in my recent memory). But if you live in an area where weather conditions are variable or less-than-optimal during certain times of the year, or training is constrained by time, or (in my case) need to manage variables (e.g., potty breaks and injury risks) a treadmill can help make sure the effort is within the "sweet spot." Tempo runs can be as short as 20 minutes or as long as an hour...even a little more, but a pace which can be sustained for longer than 70 minutes is most likely too slow.

So what constitutes a "reasonable" tempo run pace? Folks who don't feel inclined with looking at pace charts can always take their 5K pace and add about 25 seconds per mile; the average 10K pace also works well. Runners who haven't run either of those distances recently can always use the very subjective ratio of perceived effort. Tempo run pace would be about an eight or nine on the one-to-ten (one equals "too-easy," ten equals "my-chest-will-explode-in-three-steps") scale...just about 90-percent of maximum heart rate for most experienced runners.

Some software programs, such as TrainingPeaks, over time, can calculate and adjust the average pace or heart rate for a 45-to-60 minute continuous run, based on heart rate and pace data uploaded over time. Not too surprisingly, the pace at which my heart rate was at threshold aligned dead-on to the ideal "T" pace recommended in Daniels. And yes, the tempo felt the blend of both comfortable and hard; a pace I felt I could have maintained for an addtional 20 minutes had I not already done 20 as a warm-up and planned to stop.

Effective run workouts don't necessarily have to be hard, all-out efforts. It depends on the desired goal of the workout; are you working to improve your body's ability to process lactate as fuel, are you looking to improve your body's ability to take in oxygen, or do you want to get faster with what you already have? Are you patient enough for the adaptations to come?