At what point does the improvement from increasing weekly mileage become marginal?

Question

Firstly, I understand that different runners react in different ways to training, and so a specific case cannot be made to each runner.

When starting out running, there is a lot to be gained from incrementally increasing weekly mileage, eg going from 10 miles a week, to 20 miles a week. Generally, the improvement is brought about from the increase in cardio fitness, as well as the additional strength built up from the increased mileage. However, there must be a point at which the gains are very slight.

Professional, or Olympic athletes, are known to train over 100 miles/week (I believe I read somewhere that Mo Farah's average week is ~120-130 miles). The top-end of non-professional athletes often train towards to 100 miles/week mark (although that must be tricky balancing work and training!).

My question is; at what point does the performance improvement, brought about by the increased mileage, become marginal? Considering 3 popular race distances, 10km, Half Marathon and Marathon, and assuming an 80/20 (easy/hard effort) training load, with an easy long run taking ~30% of the weekly mileage.

And, for context;

As a 22-year old male, currently sitting just below 70% on the age-graded times for 5km, 10mi and Half Marathon, (18:28, 66:38, and 1:28:14 PBs respectively [no 10km raced recently]) I am considering upping my weekly training load from ~50km (31mi) to about 50mi over the course of 3 or so months, in order to attempt to head towards the 80% age-grade times for 5km, 10km and HM (16:08, 33:35, and 1:14:04, respectively). The HM PB was the result of a good 12-week training period over the summer (50km/week during and for ~6 weeks after), and the 10mi PB hit in November, however I broke my collarbone shortly after, and am restarting the training again.

Answer 1

There are two big mistakes that most amateur runners make. They go too hard on their easy days, and not hard enough on their hard days. This usually means they don't get as much out of their speedwork as they could, and they don't go easy enough to really get a good recovery.

For the average runner targeting a 5k, they can usually get by with 30ish miles a week. Add another 10-15 for a 10k, and 50+ for a half marathon. I advocate a time based program with 3 short runs, 2 medium runs and 1 long run per week with a rest day. The long run for a half marathon program should be anywhere from 1:30 to 2 hours. Your medium run is 1/2 that, and your short runs are 1/2 your medium.

So say that you have a long run currently of 80 minutes. 2 medium runs of 40 minutes, and 3 short runs of 20 minutes. Your 5k race pace is right under 6 minutes, so I wouldn't be going much faster than 7 to 7:30/mile. That brings you to a little over 30 miles at 7 min pace. Every couple of weeks, add a couple minutes to your short runs (So if you add 2 mins to the short run, it will add 4 to the medium runs, and 8 to the long). Keep that progression until you get to 50ish miles per week.

Once you get to that point, you can keep the mileage, and start adding speedwork. There are two types, interval and threshold. Interval is short distance, long recovery, done at faster than race pace. So for your 5k, current race pace is 6 minutes, or 1:30 per quarter mile. A good interval set would be a mile or two warmup, and 8-12 x .25 mile at 1:15 or 1:10, with 2-3 mins rest between each quarter, and then a mile or two warmdown. If you easily make every quarter, then next time lower the time (So 1:05-1:10). If you make most of them and then start missing by a few seconds, you're in the ballpark. This type of workout is designed to increase your top end speed (race pace).

The second type is threshold work. This is longer distances, done slower than race pace but somewhat near it, shorter recovery. So again for your 5k, a couple miles warmup, then something along the lines of 8-12 1/2 mile runs, at 1:40-1:50, on 20-30 seconds rest (This is also called on the 2:00, as your run time + rest = 2 minutes). Again, if you make them all, or miss, adjust times accordingly. (Although, if you could go out now, and do 12 1/2 miles on the 2:00, you should probably have a better 5k PB). Threshold workouts are designed to increase the time you can spend at or near race pace.

Rest, nutrition and hydration are key elements, but those vary from individual to individual, so you will need to experiment with what works best for you.

And, don't be a slave to your schedule. If you go to do a workout and you truly are just dead, don't be afraid to bag it and take a rest day. Learn what your body is telling you, sometimes it's just "I don't wanna", other times you really need that rest.

For the racing, especially the short distances (5k and to some extent 10k), you need to be able to both take it out fast, and bring it home fast. If you get into the quarter mile sprint for position on a 5k and that kills your legs, that's something you need to train for. Same for the finish, if you just can't get your legs to move faster, you either paced it just perfect or went too hard. But you should be able (most of the time) to summon a last 2-300 meter dash for the finish.

Answer 2

It's not going to be a huge issue if you bump up your training to 50 miles a week, you should still see some general improvements across your races.

It's a tricky question asking only if the running will lead to increases without factoring wider concerns, such as different types of training, diet, and to some extent rest/sleep.

And what constitutes a marginal gain in terms of just miles ran? You could run a 100 miles but your pace might not increase at all.

I'd consider changing your perspective entirely to increasing the pace in those hours once your doing 50 miles a week. Also you should consider for the longer races how you tactically conserve energy and when you push a little harder. For a 5km the aim is to just maintain a really high pace from the get go.

Although running should be the focus you'll see greater gains if you mixed in some strength training for a couple of hours spaced out in the week.

I think at the elite level you only really see marginal gains when you only 'do more' of the exercise. Greater gains come from rounding out your fitness in terms of flexibility / balance / endurance / strength.

Professional athletes might do 130 miles a week but it really tells you nothing about the team that's monitoring them or their rest periods, what they are eating and how they fuel.

Doing 50 miles a week and setting achievable pacing targets will get you into the top 80%. I would seriously doubt after 70-80 miles a week anything is more than marginal gains for anyone if it's only through running.

After that you need to go 'bigger picture'.

Answer 3

Very nice PBs :) I was approaching those times this winter but now Im taking a break to get rid of heel pain so that I can start attempting to figure out the whole speed work thing.

I think miles is a bad mark to go off of. Time on your feet is the key factor combined with the number of days your training. The main reason is because those professional athletes can jog at 6-7 min/mile and their hard workouts are 4-5 min/mile. Thats about 40% faster than me so their 100 mile week would change to about 60 miles which is funny because Ive been doing 50-70 miles/week.

I may be playing the statisticians game by making the numbers match my opinion, but Greg McMillian says the same thing about training. In fact his training plans in "YOU (Only faster)" are mostly time based except for marathon training where there are minimum distances req'd for the long run.

Ive also noticed that more miles or time on my feet helps me keep a good effort going for a longer amount of time. Last winter I stopped running longer runs and my mileage dropped while I focused on a fast 5k. After a few months my times got faster but I had a harder time to go at a strong effort for the whole distance, so I am wondering now if I ran more often maybe my times would have been even faster.

Just to brag and make a final point let me add that before taking a break I hit a half marathon at 92% average heart rate and nearly broke 1:30 on a very windy day with winds averaging at 15 mph. After freaking out about my heart rate I found an example of a professional targeting the same for a marathon, so I could possibly achieve an even higher heart rate. I got in pretty good shape to hit this heart rate by doing just 50-70 miles per week, so in my opinion doing more than 100 miles per week would result in over training.

There are a few people here that can give a better answer - maybe even a coach or two, so dont accept one until a few more answers are posted. Though I hope mine will help some :)