Part 1 Research
One of the most frequently debated subjects amongst runners is weekly mileage. How much mileage should I run? The conventional wisdom holds that higher mileages lead to improved performances; i.e. if I am running 25 miles a week now, then by increasing to 40 my performance will improve. Additionally, the high mileage training methods used by the vast majority of elite runners are frequently used as proof of the effectiveness of high mileage training programs. Does high mileage result in improved performance and is it necessary in order to maximize performance? Let’s take a look at what both scientific research and running experts have to say on the matter. We will examine this issue from 4 perspectives – research, tapering, injury, and elite training methods. All four of these topics relate to training volume and the conventional wisdom that more = better. From our examination, we should be able to formulate a reasonable approach to correct training volume.
As we begin, please realize that weekly mileage is just a way of measuring volume of training. Volume can be expressed by weekly mileage or by number of running days per week.
What does research have to say on the subject?
Conventional wisdom holds that increasing mileage leads to improved performance. What do scientific research and exercise physiologists have to say about the necessity of high volume training?
“Judging from current training methods, the greatest gains in aerobic capacity are achieved when runners train three to five days per week…Even among highly trained runners, there are some who may respond better to training four days per week, while others may thrive on six or seven days per week with two daily training sessions.”1
“As for training volume, more is not necessarily better. In a study of collegiate swimmers, one group trained for 1.5 hours daily while another group performed two 1.5-hour exercise sessions daily. Despite one group exercising at twice the daily exercise volume of the other, no differences in swimming power, endurance, or performance time improvements were observed between groups”2
“Is it better to train 2 or 5 days a week if duration and intensity are the same for each training session? Unfortunately, a precise answer is unavailable to this question. Although some investigators report that training frequency is an important factor in eliciting cardiovascular improvements others maintain that this factor is considerably less important than either exercise intensity or duration. Studies using interval training showed that training 2 days per week resulted in VO2max changes similar to those observed when training 5 days per week. In other studies for which total exercise volume was held constant, there were no differences in VO2max improvements when training frequency was 2 versus 4 or 3 versus 5 days per week…It seems that the extra investment of time needed to increase training frequency may not always be that profitable in inducing improvements in physiologic function.”3
“In one study, healthy young adults achieved a 25% improvement in VO2max after 10 weeks of interval training by bicycling and running for 40 minutes, 6 days a week…Following the same protocol…subjects continued to maintain the intensity and frequency of training for an additional 15 weeks, but they reduced training duration from the original 40-minute sessions to either 26- or 13- minute sessions per day. Almost all of the VO2max and performance increases were maintained despite this two-thirds reduction in training duration (author’s note: Short-term endurance (approx 5 min) was maintained by both groups. Long-term endurance (2 h or more) remained the same in the 26-min group but decreased 10% in the 13-min group)…However, if the intensity of training was reduced and frequency and duration held constant, even a one-third reduction in intensity caused the VO2max to decline.”4
The above study, more than any other, raises the question about the role of volume versus intensity. When volume of training was maintained (40 minutes per day, 6 days per week), but intensity was decreased by just 1/3, performance, as measured by VO2max, declined. How would you like to experience a decrease in fitness and performance even though your training volume remained high? Even more important, this study illustrates the role intensity plays in improving and maintaining performance.
“A study at the University of Northern Iowa examined the quantity part of this dilemma. In the study, 51 college-aged men and women volunteered to be part of an 18-week marathon-training program. Although the participants were reasonably fit at the start of the study, none of them had successfully completed a marathon. In fact, most weren’t even running 10 miles a week before beginning the program.
The students were divided into a high-mileage group and a low-mileage group. The high-mileage group began running an average of 23 miles a week and progressed to 48 miles a week by the end of the 18-week program. The low-mileage group ran 20 percent less mileage, starting at 18 miles per week and maxing out at 39 miles. Both groups ran identical weekend long runs, starting with an hour and advancing to 21/2 hours.
The quality of training for the two groups was also identical. Both groups trained at 75 percent of their maximum heart rate, a pace that quality-wise could be considered moderate.
The key difference between the two groups: The high-mileage group trained 6 days a week, while the low-mileage group only trained 4 days a week. On Mondays and Wednesdays the low-mileage group didn’t run while the high-mileage group ran for 45 minutes.
At the end of the 18 weeks, the runners in both groups had nearly identical stats: Exact same reduction in percentage of body fat (10 percent). Equivalent gain in muscle mass (3 to 5 percent). Similar improvement in max V02.
And when it came to the most important stat of all–marathon-finishing time–the two groups were equally similar: the men in both groups averaged 4:17, and the women averaged 4:51. So despite taking 2 extra days off per week, the low-mileage runners performed just as well as the high-mileage runners during the marathon.”5
There are two really interesting things about this study. Conventional wisdom says that beginner runners experience the greatest performance improvements and that at relatively lower mileages increases in mileage have the greatest effect, i.e. increasing mileage from 20 to 40 miles a week has a greater impact than increasing mileage from 80 to 100 miles per week even though both are an increase of 20 miles per week. Since this study used both beginner runners and relatively low mileage, conventional wisdom would have predicted a significantly greater magnitude of improvement for the high mileage group in this study. Conventional wisdom would have been wrong. Instead, both groups performed equally well, indicating that increased mileage had no effect on performance. Notice that the intensity and specificity (i.e. 75% and weekly long run) were the same for both groups and that both groups performed the same. Intensity and specificity caused the improvements observed in this study.
A study conducted by the Naval Health Research Center examined the changes in fitness of 1703 basic training recruits assigned to 25 divisions between April and August 1996. The authors stated, “The purpose of this study was to determine whether there is a relationship between overall fitness improvement and varying amounts of running and movement mileage.” The study classified each recruit’s initial fitness as either ‘Excellent-Superior’, ‘Good’, or ‘Poor-Fair’, by determining baseline fitness with a 1.5 mile run. During the course of the study, the running and movement mileage amongst the 25 divisions varied widely. At the end of the study, the Poor-Fair group had improved their run time by 15.6%. The Good group improved by 7.3%. The Excellent group improved 2.9%. The study concluded that “the magnitude of fitness improvement, as measured by run time improvement, was directly related to baseline fitness level, but not related to movement mileage or high intensity run mileage accrued during training.”6 Don’t misconstrue the authors’ use of the term high intensity run mileage as meaning speed work. Typical basic training runs are not speed work, but are instead increasing distance runs culminating in a final distance run conducted in formation. In this case the authors are referring to the divisions who ran significantly further overall distances than the average.
“But the only way we shall ever establish the ideal training program that produces maximum benefit in terms of enhancing performance while minimizing the risk of injury or overtraining, with minimum input, will be by studying, in carefully controlled experiments, the effects of different types and amounts of training on competitive performance. Sadly, though, there are too few of these studies. In 1991, in one of the first studies of its kind, David Costill and colleagues found that the performance of a group of collegiate swimmers did not improve when they increased their daily training volume from 90 to 180 minutes. In fact, the sprinting performance of the longer-training swimmers was marginally impaired by their heavier training. There is an almost total dearth of similar studies conducted among runners.”7
The bottom line is that there is insufficient research comparing different training protocols to each other to definitively say what training volume is optimal. However, there is enough evidence to suggest that the conventional wisdom of more = better is inaccurate to some degree and that intensity and specificity of training play a much more important role in performance than does volume of training.
- Costill, D. (1986), Inside Running, Basics of Sports Physiology, 103
- McArdle, Katch, Katch (1996). Exercise Physiology, 406
- McArdle, Katch, Katch (1996). Exercise Physiology, 406
- McArdle, Katch, Katch (1996). Exercise Physiology, 408
- Eyestone, Ed, (2003), Runnersworld.com
- Trank TV, Ryman DH, Minagawa RY, Trone DW, Shaffer RA. Med Sci Sports Exerc. 2001 Jun;33(6): 1033-8.
- Noakes, T (2001), The Lore of Running, 4th ed, 171