Higher or lower?

With elite marathon runners regularly knocking out more than 100 miles a week in training, many of us believe that upping our training volumes is a recipe for success. But is adding extra miles really that beneficial? Roy Stevenson asks: just what is better for distance running – high mileage or low mileage?

Since the dawn of distance running, coaches and runners have debated the merits and disadvantages of high mileage over low mileage. In an attempt to answer the age-old question about which is most effective, we’ve reviewed what the coaches and exercise scientists say about the merits of high mileage run at low intensity, versus lower mileage done at a higher intensity. The answer is not clear-cut because the research is conflicting.

Many runners and coaches have questioned whether it is necessary to run 100 miles per week for optimal aerobic conditioning, as Arthur Lydiard has dogmatically preached since the 1960s. At what point does high volume running reach the point of diminishing returns? Can you get better results by running less at a faster pace? Where does faster running fit into the overall scheme of training programmes? Does high mileage at low intensity causes more injuries than lower mileage done at a higher intensity? To date, our answers to these questions are being answered as much by experience and intuition as by research.

Photo: Increasing your mileage suddenly can cause more injuries. A good training foundation will help you cope with the demands of faster-paced running

A question of physiology

One thing is clear: many runners cannot handle high mileage whether it’s due to faulty biomechanics, lower motivation levels, an immune system that crashes under the stress, or insufficient energy to sustain this volume of running. By the same token, many runners thrive on high mileage - they’ll cruise through a 20-miler, grinning like a Cheshire cat.

First, then, why do runners need lots of long, steady paced running? We need some high mileage to prepare us for the rigours of the faster running that is going to follow. Jack Daniels, PhD, in his book Daniels’ Running Formula, says we “need to spend some time subjecting the body to low-intensity stress, mainly to prepare the body for more quality training, and also to develop those components of fitness that respond well to low-stress training”.

In favour of long running, a study by Esteve-Lanao compared the influence of different volumes and intensities on performance in eight sub-elite runners. They found a strong relationship between time spent training at low intensity and 4k and 10k performances. Further proof was provided by Fiskerstrand and Seiler’s study of Norwegian rowers. Between 1970 and 2001 they showed improvements in VO2 max of 12 per cent and improved 6-min rowing ergometer performance by 10 per cent when low-intensity training volume increased by 20 per cent, from 924 hours/year to 1,128 hours/year, over this time period.

In his investigation into the topic of high volume and high intensity training, Paul Laursen concluded that “it would appear that the insertion of these low-intensity training sessions has a positive impact on performance, despite being performed at an intensity that is markedly lower that that which is performed during intense competition”.

Here are some of the main physiological changes that happen to our cardio-vascular, muscular, and neuro-muscular systems when we become well conditioned aerobically.

Timescales

How long does it take to get solid gains from high mileage? Depending on our starting fitness, we need six-ten weeks of higher mileage to reap the benefits, according to former head of Ball State University’s exercise science programme, David Costill, PhD, in his book Inside Running: Basics of Sports Physiology, because our body adapts quite slowly to it.

What does the research say about the optimal training distance for runners? A study by Costill in 1976 found that elite US runners cover between 100-150 miles per week. Fink’s study in 1977 shows that VO2 max increases in runners between 50 and 75 miles per week. Beyond that, lab tests show no further improvement. Costill theorises that optimal mileage for runners is between 60 and 90 miles per week and is the point of diminishing returns.

There are few studies on total weekly mileage run by distance runners, so it’s hard to establish the optimal training mileage for runners in practical terms. Lumian’s study of marathon runners in 1965 found that 60 per cent ran 45 to 52 miles per week, and a staggering 40 per cent ran more than 100 miles per week.

Yet, a study on first time marathoners by Grant in 1984 shows that high mileage may not be as necessary as we believe, at least for success in the marathon. This group found that marathon runners do not need excessively high volumes of mileage to complete their event. The researchers surveyed 88 beginner runners in the 1982 Glasgow Marathon, and found they averaged only 60km (38 miles) per week for 12 weeks before the race, ranging from 24km (14 miles) to 104km (64 miles).

Photo: Make sure more miles doesn't just mean junk miles. Training should be a mix of lower intensity running and shorter, faster-paced efforts

Why do we do it?

If the research shows we don’t need 100 miles per week, why do so many runners persist with this level of mileage? We can only guess at the reasons. It is likely that long distance running sessions (in excess of 19 miles) strengthens the connective tissue and muscle fibres, better preparing them for the rigours of further long distance training and racing. Perhaps Lydiard’s figure has set the gold standard, and runners are reluctant to do any less. When it comes down to it, runners will believe a coach who has achieved success in the field over what an exercise physiologist finds in a lab setting.

Most savvy coaches agree that the real key to running success is to establish how much you can handle before breaking down, and then work within that range, to allow a safety margin for good health and injury prevention. Perhaps rather than using a one-size-fits-all 100 miles per week guideline, we should find our personal limit, somewhere between 60-90 miles per week. And, as Costill advises, runners who cannot handle 60 miles per week are better off running less than this to avoid becoming overstressed or over-trained.

Certainly one of the biggest criticisms of high mileage is that it can lead to excessive ‘junk miles’ done at a slow pace, which does little more than boost the runner’s mileage total for the week. This applies as much to elite runners as recreational runners. A 1991 study of 13 elite New Zealand distance runners by Robinson showed that many runners do high mileage with little high intensity, and therefore may not be as productive as if they had done some shorter training efforts at a faster pace.

A study by Seiler in 2006 had similar findings. They estimated that well-trained athletes, including world-class elite runners, regularly perform 75 per cent of their training at intensities below lactate threshold, despite competing at much higher levels. It is likely that, had the runners in both these studies trained at a higher percentage of their anaerobic threshold, they would have achieved faster performances.

And here is where we get to the crux of the contentious issue of high versus low mileage. The problem is that most long distance training is done at considerably slower than racing pace, and therefore does little to improve anaerobic capacity and does not develop the neurological patterns of muscle fibre recruitment that are needed during a race. The benefits of faster paced training, whether of the interval training or tempo pace running variety, cause an entirely different series of adaptations that are essential for distance racing success.

Therefore, it is crucial that much of our running is done at a pace specific to the distance we train for. If, for example, we are training for the marathon, and want to complete the 26.2 miler comfortably and competitively, we obviously need to run higher mileage than say, a 10k road racer, while conversely, a 10k runner will be better off at a faster pace and doing less mileage than the marathoner.

Coaches and exercise scientists agree that both low intensity, longer mileage, and shorter, higher intensity running are important training elements, no matter what event we race over - but it’s the ratio of these two training factors that is the key. Our training must have a blend of shorter, high-intensity and high volume, lower intensity training for optimal performance.

Which training method causes the most injuries?

Increasing our mileage suddenly has been found to cause more injuries, but high intensity training also increases injury rate. Long distance running tends to cause more repetitive strain injuries, where a weak point in the runner’s bio-skeletal framework is worn down over weeks or months of running, and the injury eventually grinds him to a halt. High intensity training injuries tend to be more of the sudden muscle strain variety.

Just as many runners are injured during their high intensity training phase as are injured during their conditioning phase. Regardless of the cause, it is wise to allow recovery days between both types of sessions, and to ease into high volume or high intensity workouts.

A series of experiments using higher intensity running for marathoners at Furman University Human Performance Laboratory, South Carolina, resulted in some interesting performances. The running programme designed by Pierce, Murr and Ross, described in their book Run Less Run Faster, shows that we can improve our VO2 max, running speed at lactate threshold, and running speed at maximal oxygen consumption, with as little as three days of high-intensity running per week plus a couple more days of cross-training. Seventy per cent of their runners ran personal best times in the marathon, or completed their first marathon, using this training regimen.

Perhaps runners who feel compelled to do more than 90 miles a week might be better off inserting some cross-training sessions (swimming, deep water running, cycling, etc.) into their programme. This would maintain their fitness, prevent boredom, minimise risk of injury because of the variation in exercise, and possible boost VO2 max if done correctly.

There is something that you may be able to learn from this. If you’re a high mileage, low intensity runner, you will undoubtedly benefit from doing some shorter, higher intensity training. Likewise, if you’re a short, fast runner, who considers 10 miles to be a major long run, you’ll be surprised at how much you can improve by working on your base fitness for a few weeks before commencing interval or tempo running.