Niall O’Crualaoich is back again with an in depth look at strength training and the principle of interference.  And no that’s not referring to what his wife does when he’s trying to use the squat rack in his kitchen…!

The topic of weight training for runners turns into a complicated discussion for most club and State / national distance runners. While we understand the need for injury prevention strategies, some runners fear weight training as they suspect a detrimental effect on performance. In conditioning this is called the principle of interference. I will discuss this principle in relation to distance runners (marathon distance and above) but as in life there are different opinions and you should educate yourself before undertaking any course of action. The best thing, in my opinion, you can do for your running is to get a coach or join a running club. A club will give you access to coaching and a wealth of knowledge as well as providing motivation.

But I digress; I want to touch on the science of running and a principle where most runners (and some coaches) could do with contemplating.

The principle of interference may be defined as

Training to improve some components simultaneously may result in compromised gains in one of these components” (Setanta College, 2010).

This implies that training certain components of fitness at the same time can lead to the interference effect. For example, training for hypertrophy (increasing muscle size) and increasing aerobic stamina at the same time will lead to the athlete making slower progress (or no progress at all), even though there may be increases in both of the components being trained just not to the same level as training compatible training elements together. I, as a coach would have subscribed to this principle in the past. I believed, at one time, that to be a better long distance runner, one had to run long, nearly to the exclusion of other fitness components such as speed and weight training. This logic and the anecdotal advice from other coaches had led me to believe, in the past, that the principle of interference was absolute.

Anecdotally from numerous runners I have heard a belief that strength training makes the athlete too big and bulky and therefore too slow. While excess weight in the long distance runner does indeed make the athlete slower (SC Dennis, 1999). Performance is determined by an advantageous strength to weight ratio and excess fat, adds to the weight and contributes nothing to the strength or power output of the athlete. Logically this would give the lighter athlete the advantage in a race. This logic only holds up if the lighter athlete is not too far under weight for his or her body height and type. (Lebrun, 2006) As to where this optimal bodyweight range lies? That is dependant on so many factors and is well outside the scope of this very general article.

What I have learnt over the years has made me question the absolute nature of interference and its application in the strict sense. Hickson wrote the “…interference of strength development by simultaneously training for strength and endurance” in 1980. (Hickson, 1980) The same author wrote eight years later about how strength and endurance combined amplified endurance performance. (Hickson RC, 1988), This does not directly contradict his original work but shows that the principle of interference is not absolute. And neither should the training regime of any athlete be so one sided. In this I mean that nearly all methodologies for marathon training now include speedwork, so if speedwork aids the long distance runner (being the opposite of long slow distance and should logically interfere with Long slow distance), why should the correct weights program not do the same?

Paavolainen et al also showed a marked improvement in runners while concurrently training with explosive strength training in well trained athletes. (Paavolainen L, 1999) This study showed no increase in the athletes VO₂ max, but the study showed the explosive strength training improved the runner’s neuromuscular characteristics and running economy.

Millet et al showed that heavy weight training led to improved maximal strength and running economy with no significant effects on the VO2 kinetics pattern in heavy exercise with a study done on triathletes. (Millet GP, 2002)

And while these studies that show that heavy or explosive strength training show no real effect on the VO₂ kinetics (Oxygen uptake) they also show no detrimental effect on running. In actual fact they all show running improvement. Better running economy can only benefit the long distance endurance and maintain the efficient gait for longer which in turn lead to better race times.

Therefore I have to conclude that the principle of interference as it applies to coaching of endurance athletes has shifted monumentally in recent years. The incorporation of strength training for both injury prevention, as I have in the past and for performance improvement going forward is a must for most runners. Most of these studies have shown that weight training in both elite and novice adults has improved running performance. Of course one must be mindful of fatigue and over training while my athletes train two opposing components of fitness simultaneously. This I believe to be the biggest threats to an endurance athlete no matter what the sport or the training method being used in that training cycle. Overtraining syndrome is a very real and present danger that does not just affect elite athletes but every runner. But that is a topic for another day!


Hickson RC, D. B. (1988). Potential for strength and endurance training to amplify endurance performance. Journal of Applied Physiology , 6595) 2285-2290.

Hickson, R. (1980). Interference of strength development by simultaneously training for strength and endurance. European Journal o Applied Phusiological Occupations Physiology , 45(203)255-263.

Lebrun, C. (2006). The female athlete triad. Women’s Health medicine , 3(3)119-123.

Millet GP, J. B. (2002). Effects of concurrent endurance and strength training on running economy and .VO(2) kinetics. Medicine and Science of Sports and Exercise , 34(8) 1351-1359.

Paavolainen L, H. K. (1999). Explosive-strength training improves 5-km running time by improving running economy and muscle power. Journal of Applied Psychology , 85(5)1527-1533.

SC Dennis, N. T. (1999). Advantages of smaller bodymass in humans when distance-running in warm, humid conditions. EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY AND OCCUPATIONAL PHYSIOLOGY , 79(3)280=284.

Setanta College, I. (2010, Week 5 Lecture 1). Module 1. Setanta College.

Niall O’Crualaoich

One thought on “Interference (or should Runners weight train or not?)

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>