Predicting Race Potential

There are a number of methods to predict your potential time at a distance from a distance and time you already know or have achieved. Some require some solid math and patience (especially for the math-challenged). Other approaches use a chart that you just look up your corresponding distances/times. And of course, some are put online and take the mental gymnastics out of it. There are actually quite a few formulas available. But this should give you an introduction to using them.

Here, I’ll demonstrate the calculations for; Horwill’s Law, Running Trax tables, Galloway’s formula, vVO2max time trial test. Then I’ll compare them with real performances (mine).

In each case, the distance/time is assuming an all out race effort. So, when it says your “mile time” it means an all out single mile time trial or raced mile on a track while feeling fresh and with a complete and proper warm up in moderate environmental conditions. A flat and precisely measured road course could subsititute.

Horwill’s Law is simple and straight forward math. Take a distance and time and determine the pace per 400 meters (Ok, a quarter mile will be close enough too.. except for the engineers and accountant types in the readership). Now, every time you double the race distance, add 4 seconds to that 400 meters (elite are 2-3 seconds per 400). You can just as easily add about 16 seconds per mile pace. So, if you can run a mile in 8:00 we could estimate that you can run at a pace of 8:16 per mile for two miles or about 16:32. Or you could run about 8:24/mile for 5K which is 26:02.

J. Gerry Purdy developed a point scale for distances called Running Trax. It is based on years of statistical data analysis. For simplicity, “world bests” sort of anchor the high side and equaling 1000 points. Since tables have not been updated recently, some world records actually are higher than 1000. There is a software that you can obtain with the book. If you can run at 8:00 mile that is awarded 230 points. A similar 230 point effort for two miles would be 16:25 (229 points). Or you could run 26:12 for 5K.

Jeff Galloway uses the following method. It is based on personal data and experience. Take your one mile time and adjust it as follows: add 33 seconds for your pace for a 5K; or multiply it by 1.15 for 10K pace; or multiply by it by 1.2 for half marathon pace; or you can multiply it by 1.3 for marathon pace. So, if you run a 8:00 mile this system estimate that you could run 8:33 per mile for 5K or 26:30. It is limited to those distances but you could interpolate intermediate distances/times.

A scientific method based on research of many elite runners as well as supported in many research studies is to use a percentage of your vVO2max. You can find this pace by doing a 6:00-7:00 time trial. The research varies a bit depending on whether we are measuring elite or completely non-conditioned runners (from 4:00 to as much as 8:30, with most of us falling in between and the most common number used is 6:00). Personally, as a coach I use a 1600 or 2000 meter time trial depending on the caliber of the runner. With this method you divide your per mile pace by the percentage of VO2max attained by well trained individuals to get your projected pace. You divide by .95 for 5k, .90 for 10k, .80 for the marathon. Marathon times vary widely depending on level of ability and conditioning however. If you time trial yielded 8:00 then your projected 5k pace is 8:25/mile or 26:06 for the 5k. It is also limited but you could interpolate intermediate distances/times.

As you can see, these are reasonable projections and each offer similar times. (26:02, 26:06, 26:30, 26:32) You will find variations in calculations as distances move up or down. Some will seem more accurate on distances that are close together (i.e. 5k projected to 10k) and less accurate the larger the gap (i.e. mile to marathon). You will probably find one method or formula that just is easier to use.

There is an important caveat to all this prediction stuff. It assumes that you:
1. Have completed appropriate training for the given projected distance.
2. The course is flat.
3. The weather is moderate (i.e. in 60-70F degree range).
4. The race is appropriately paced (i.e. even paced).
5. You are appropriately rested, feel good or fresh and it is a “good” race.

My experience with using these is that none are perfect. Some are easier to use than others. Some may be more accurate for beginners than more experienced runners. For some individuals one formula may be more accurate than another formula. But, be careful not to advocate one formula “because it is accurate for you”. It may not work as well for someone else. My personal preference is a scientific basis so I use the vVO2max research approach. Ultimately, what is easiest and works for you is what is important. As you can see from the table with my personal examples, they are all reasonably close.


These calculations also reveal what I trained for most of the time – 5k-10k distances. I never trained for the half mile or half marathon. I was only semi-serious about the marathon and have only run four half-marathons ever. I believe I could have run in the 2:28 and 1:10 range for each respectively.

A real mis-use of these calculations is to take them as gospel. The five assumptions I listed are seldom attained. Therefore, it will be rare these are absolutely precise. In any event they can do several very beneficial things.

1. They provide an estimate of your abilities if you train appropriately.
2. They give you a reality check on “goal” times you’ve set for various distances.
3. They provide guidance for “goal paced” runs.
4. They provide a nice comparison of efforts you have already run at various distances.
5. If there is a wide discrepency in your projected and real times, it most likely indicates you need to change your training.
6. They can provide motivation.

 Use them in good health!


About Dean Hebert

I’m a mental game coach, author and speaker. I work with individual athletes, parents, coaches, and teams on sports performance enhancement. Beyond my academic post-graduate work in sports psychology - the psychology behind athlete performance – I am a certified Mental Games Coaching Professional (MGCP) and certified hypnotherapist. I’ve authored several books and hundreds of articles. “Coach, I didn’t run because…” (2008) is a seriously light-hearted look at making excuses not to workout and how to overcome them. “Focus for Fitness” (2009) and “Screw the Goals Give me the Donut” (2010) are two of my eBooks on mental game approaches for the everyday athlete. I wrote these because I believe that everyone can benefit from the powerful mental techniques that the world’s best athletes use. I have been cited in Runners World, Best Health magazine (CN), SWEAT Magazine, and the Washington Examiner amongst many other publications. I have been a featured mental games coach in Runner’s World and for the internationally acclaimed trail running resource - I also regularly appear on sports and fitness talk shows such as LTKFitness, Runnersroundtable and for more than three years I have co-hosted a weekly video series with Coach Joe English for I specialize in mental toughness training. My clients include tennis, synchronized swimming, golf, race-kart, soccer, motocross, volleyball, MMA, cycling (road, off-road, time-trialist), running, duathlon and triathlon, basketball, football and baseball athletes. I have coached world-class athletes and athletes internationally. I have a passion for working with youth athletes and helping them apply mental game skills and techniques to all areas of life. Most importantly, my aim is to have people enjoy sports and life to their fullest through peak performances.
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3 Responses to Predicting Race Potential

  1. I would really appreciate your help. I’m running a marathon on May 10 and would like to do better than 3:39. I ran a 30k in 33 min at the end of March. My mileage is around 75-80k/week. I’ve done a lot of training on hilly ground, some hill workouts, some tempo sessions and in the last three weeks one speedtraining session/weekly–these workouts started with 1st week: 2 sets of 300/400/300; 2nd week 2 sets 400/300/400; 3rd week: 200/400/800/1200/400/200. During the last workout I tried to be consistent averaging each 200 at about 50-51 sec but did 45 sec in the very last 400.
    I have done 3:39 on the course that I am running on May 10th but would really like to do better. The 30k at 2:33 could have been under 2:30 –I went out a bit too fast I believe.
    Your help is greatly appreciated giving me some guidance ion what I should do pacewise. It takes me at least 30 min to warm up at the bigiong of a long rrun/race so I would definitely want to be conservative with this particular race to ensure that I don’t jeopardize what I would like to achieve.
    Very best,
    Clara Northcott
    P.S. I am a 800 specialist in my age category in Canada-my best time is about 2:47 (50-54)

  2. Dean Hebert says:

    First, keep up the good work on that 800… wonderful times.

    Ok, without knowing every detail of your training it’s hard to make definitive recommendations. Let me start with observations then get to the race recommendation. At this point there is nothing you can do on the training end, it’s too late for that. But I’ll make some training observations from what you have stated.

    Your mileage is more than sufficient. For a 3:00-3:30 marathoner only a few weeks and only a few runners need to be at 80k (50 miles) per week. Most all my runners are 55-70K per week (35-45 miles). A critical element in marathon training is goal paced running. Your goal pace is for sub-3:39 (about 5:10/k or 8:18/mile). Doing more runs at that pace and less miles will serve you far better. Efficiency in running is pace-specific. By the way a little known fact: older runners will benefit more (i.e. get in better condition) from higher quality running than from adding more miles.

    Quality work as you mentioned is a good direction. However, it’s added in too late. It needs to be integrated throughout all phases of your training. This is critical to overall conditioning. In the past coaches used to think you only added it in towards the end of training programs for “peaking”. This is completely unfounded in the science today. Quality work for marathoners should be longer reps (400-1600 reps).

    Tempo runs @ your 10k race pace for 2-3 miles is optimal and should be integrated all along the program as well. Not necessarily every week but regularly.

    Hill work is good as an early season strengthening workout. After that however, it will tend to slow you down… you’ll be strong and slow. So, gravitate away from hills as the program progresses. If the course you will be running is hilly on race day, then of course running hilly courses during training is important but that is different than doing hill repeats as a phase.

    One final training point – be sure your last long run is at least 3 weeks prior to your race or you will show up on race day feeling fresh perhaps but with muscle tissue damage still lingering from that last long run… it’ll get you in the later miles.

    Ok, now for your race. Your 30k pace indicates you should be able to do your sub-3:39 marathon. So, pacing indeed becomes the number one variable you now control along with hydration/nutrition. So, the rule of thumb is goal pace approximately plus or minus 10 seconds per mile is what you should shoot for in your pacing. Slower than that and it is doubtful you will make up the time deficit. Faster than that, you will not have banked any time at all – in fact you will lose far more through the additional fatigue created from a too fast start.

    So, with a goal of about 8:15/mile (5:09/k); go out no slower than about 8:25/mile (5:15/k) and no faster than 8:05/mile (5:03/k). Of course the terrain of the course must be considered, I’m assuming a fairly level course for pacing purposes. Naturally, an uphill section will slow you and a downhill will speed it up a bit.

    I hope this makes sense. Good luck.. let me know how you do.

  3. Clara Northcott says:

    Hi, Many thanks for this.
    I will most definitely apply your suggestions and will let you know how I progress.
    Many thanks, Clara

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