Whether your motivation is Boston, Hawaii, your age group, or the clock, improvement is the goal for most endurance athletes.While we exercise for mental clarity, health, and to spend time with friends, I’ve yet to meet an athlete who doesn’t pay attention to the clock at the finish line. Often, race results are the only feedback mechanism an athlete uses. Unless you race regularly, that’s not the best way to determine what worked, or did not work, while preparing for an event. Training metrics can be as general or detailed as you want, but to stay on track, you must measure and analyze something!
Your background, personal preferences, and/or a coach will determine what training metrics you should use. They range from RPE (Rate of Perceived Exertion, or how you feel while exercising) to more technical concepts, such as power output. Each metric has its pros and cons, and if you are unable to interpret the information you obtain, it won’t be of much use. Running out to buy a power meter without instruction or an understanding of power values, for instance, will do little more than give you a new gadget to play with. With that in mind, let’s look at some common training metrics.
RPE, or rate of perceived exertion, is based on one of two numerical scales and represents how hard you feel you’reworking. The Borg Scale is 6-20, with 6 representing no exertion and 20 maximum exertion. A 0-10 scale, with 0 representing no exertion and 10 maximum exertion, might be a little easier to use, since each number represents a 10% change in perceived effort. If you feel like you are exercising at 70%,then you are at a 7 on the 0-10 scale. For example, if you ran 3 miles at a 7 last week and the same run feels like a 6 this week, you can see that you’ve improved. The downside with RPE is its openness to interpretation. If you are new to endurance sports, RPE will provide sufficient feedback for your first year or two while developing your aerobic base. Beyond that, you’ll want a more accurate way to measure your progress. At the same time,there’s no reason to use RPE exclusively if you are new to endurance training.
Pace, determined by distance and time, is a commonly-used metric. Let’s stick with our 3-mile run example. If your run took 27 minutes last week, you were running at a 9-minute per mile average pace. This week, the same 3-mile run took only 26:30 so your average pace was 8:50 per mile, a 10-second improvement in your average pacing. The downside of pace is the number of variables that must be controlled for accuracy. A 3-mile run on a track with no wind at a comfortable 65 degrees is not the same as a 3-mile beach run on a windy day with the temperature at 95 degrees. Weather and surface conditions need to be similar when using pace; either that or you must make an adjustment for varying conditions.
Heart rate monitors are another feedback mechanism that measures your progress in beats per minute (BPM). This reflects the intensity of your workout. If we take our 3-mile run example and compare average heart rates from one week to the next, we can see if the run was easier or harder based on heart rate. If you averaged 150 BPM last week and did the same run at 145 BPM this week, we would deem this an improvement in cardiovascular efficiency. The drawback to heart rate is similar to pace. Several variables can impact the data. Caffeine, lack of sleep, terrain, and environmental conditions can skew heart rate data and should be considered when analyzing heart rate information.
Power is the new kid on the block when it comes to running metrics, but it has been used widely in cycling. Power is considered the most direct measure of output without the variable considerations needed in the metrics discussed previously. In cycling, power meters measure how much force a cyclist applies to the pedal and is not impacted by perception, conditions, terrain, or nutrition. Power meters for running are new to the market and base their power numbers on algorithms. It’s the same idea as cycling, measuring how much force your foot applies to the ground. Power in cycling is well established,and as technology in running improves, it will become the most accurate metric to determine output. The downside to power is the learning curve. It takes some time to get acquainted with the values and what they mean.
Each training metric has its pros and cons, but the take-home message is the importance of tracking and analyzing something to determine the efficacy of your training. For someone new to endurance training, it is easy enough to start with RPE and then heart rate followed by pace and power. There’s nothing wrong with moving straight to advanced metrics as long as you understand how to interpret them and don’t fall into the “paralysis by analysis” trap. Just make sure you measure something, watch how that value changes over the course of your training program, and then make adjustments, as necessary.