Results from a 5K or 10K race can also be used to determine your FTPa, LTHR, and/or FTPw for running or cross country skiing.
If your all-out 10K time is close to an hour; then you can use the average pace, heart rate, and/or power from the race as your FTPa, LTHR, and/or FTPw. If you’re new to running or cross country skiing, you can use the same data from a 5K race as your FTPa, LTHR, and/or FTPw. These results are often good estimates without further manipulations required.
If you’re an experienced runner with a 10K time less than 45 minutes; then your race results from races shorter than a 10K will be higher than your FTPa, LTHR, and/or FTPw (which, remember, corresponds to a race effort of about an hour in duration). In that case, the race results are similar to the results of the 20-minute time trial discussed in the previous section. So, multiply your average heart rate or average power from a 5K running race by .95 to arrive at your LTHR or FTPw. This is a general rule, so you may need to play with this a bit as you gain experience interpreting the results.
For example, let’s say you run a 5K in 20 minutes with an average heart rate of 170 and average power of 285. Multiply 170 by .95 to arrive at an estimated LTHR of 162. Multiply 285 by .95 to arrive at an estimated FTPw of 271.
To determine pace from the race results, first consider the type of course it is. Remember, pace zones are relevant to the particular terrain. If the race was mostly flat, then the average pace of the 5K race could be used. But if the course was a trail race with lots of climbing, then you wouldn’t want to use the average pace as the basis for your pace zones that you plan to use during track workouts.
Running coach and exercise physiologist Pete Pfitzinger notes that experienced runners at shorter distances have a FTPa that is typically 10-15 seconds per mile slower than 10K race pace and 20-30 seconds per mile slower than 5K race pace. If this applies to you, then you can take your average pace over a 5K or 10K race and add a per mile time within those ranges to estimate your FTPa. For example, if you run a 5K in 18 minutes with an average pace of 5:48/mile; then your FTPa would be somewhere between 6:08/mile to 6:18/mile.
Another way to find your FTPa based on these 5K results is to use the Alp Fitness Equivalent Running Performance Calculator to find an “equivalent running performance” for a race closer to an hour; then determine the average pace for that equivalent performance. Since FTPa is the maximal pace you can consistently sustain for 45 minutes to an hour, the pace of that equivalent performance would be a good estimate of your FTPa. For example, plugging a 5K time of 18 minutes into the equivalent running performances calculator shows an equivalent 10-mile performance of 1:01:36 or 6:09/mile. This pace could be a good estimate of your FTPa — and it’s comparable to the Pfitzinger estimate used above.
Remember, extrapolating from any field test or race merely gives an estimate of your threshold values. As you gain experience using field tests and examining race results, you’ll learn to more effectively interpret the results and dial in your threshold values.