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Last column I wrote about the dose-response phenomenon and the need to stress a

system, but not over-stress it. The Overload Principle is a component of this idea that

identifies the positive stressors that lead to appropriate training adaptations (look up

Hans Selye for its genesis). Within the Overload Principle is the idea that stresses must

be specific, are reversible, and are individual. Each of these parameters is worthy of a

full column. In this column, I will discuss the concept of specificity since in recent years

specificity has been turned on its head.


The concept of specificity is pretty easy to understand – you train what you want to get

better at. For example, to become a better bike racer, you ride bikes rather than walk a

dog. The reason for these specific adaptations is the way the body senses stress and

does something about it. I have touched on this a couple of times, but the cell senses

something that is unusual or difficult, relays that information to its machinery, and begins

making proteins to make that stress less “stressful” the next time it encounters it. For

example, you do bicep curls (bad example for bike racing since big biceps are not a

prerequisite for bike racing) and your muscle gets bigger over time because the muscle

cell is told to make more proteins that help with force production. Although the bicep curl

example is easy to understand because of the visual results, more appropriate for bike

racing is that riding your bike to increase the making of structures that deliver and use

oxygen to produce energy. These adaptations are what we know as “training”.



Depending on how you learned to train, or who dictates your training, there are a

variety of training styles. Some think that you need to ride many miles at a slow pace,

while others question the utility of this approach because it is not how you race. Some

advocate training at thresholds, whereas others avoid thresholds and train above or

below it – again because unless you are doing a time trial, you don’t race continuously

at a threshold (as an interesting aside, when the training patterns of elite Scandinavian

skiers have been explored, it is apparent that almost all training lies at very high or very

low intensity with very little at “thresholds”). If you adhere strictly to the importance of

training specificity, you would train like you race. However, what the demands of racing

are was not entirely understood for a long time, until the appearance of powermeters.

One of the biggest advantages of powermeters is that they allowed athletes to quantify

the demands of racing so that those demands could be repeated in training. The ability

to quantify the demands or racing was important to adding more specificity to training.

To this point, I have made the point that the body adapts to the stresses placed on it;

therefore, you impose specific stresses to improve those specific areas. Traditional

endurance exercise training induces numerous adaptations in muscle such as the

making of mitochondria and the enhanced ability to use glucose and fats as fuel,

which makes one better at sustaining work for a long period of time. Therefore, to be

a better aerobic endurance athlete, you have to train with many hours of prolonged

aerobic activity…or do you? In 2005, the first of a number of research articles came

out demonstrating that short, high intensity sprint efforts had the same physiological

adaptations that one would expect if they were doing prolonged endurance exercise.

In the first study, 4-7 all-out 30-second sprints performed 6 times over two weeks had

the same benefits as traditional endurance training. This study was amazing in that it

flew in the face of training specificity. If was very surprising that efforts that were only

30 second long and did not require oxygen (because the exercise used non-aerobic

energy systems) were having adaptations that improved the aerobic system. Since the

original study, many studies have tested various permutations of the original protocol

and reproduce endurance exercise-like effects. Can you imagine the impact that this

had for those that don’t like to exercise? In a mere 2.5 min of accumulated exercise,

one could have the same benefit as an hour of exercising. The popular press latched

onto this study quickly.


What does this mean for you as a cyclist? It is hard to say for sure, but high intensity

interval training (HIIT), also known as sprint interval training (SIT), definitely has its

place in the training arsenal. For those that are time crunched (think masters athletes)

this type of training is really important. Obviously, the high intensity intervals solely by

themselves are not a practical strategy because they will lead to accumulated fatigue

and burn out. In addition, for those that are weight conscious, the caloric expenditure

from these workouts might not be enough to keep caloric expenditure high enough

to manage or lose weight. But, on the plus side these workouts offer a way to have

measurable improvements with less time investment. Also, they are a way to reach

peak levels of fitness. As a scientist, however, the most interesting part about these

workouts is that they total defy the concept of specificity and leaves one wondering why

efforts that don’t require oxygen result in adaptations that increase oxygen delivery and



Studies of high intensity interval training continue and the most interesting application

of the research has been in using these exercise approaches for chronic disease

prevention (again, think of those that dislike exercise). The positive health effects

of prolonged activity can be realized in very short bouts of exercise. In addition,

accumulating some exercise-training benefits from these brief bouts of exercise can be a

gateway to more prolonged exercise in those that previously did not exercise. For peak

performance, or simply disease prevention, the concept of specificity got a whole lot

more complicated.


More reading:

Burgomaster KA, Hughes SC, Heigenhauser GJ, Bradwell SN, Gibala MJ. Six sessions

of sprint interval training increases muscle oxidative potential and cycle endurance

capacity in humans. J Appl Physiol. 2005 Jun;98(6):1985-90.

Gibala MJ, Little JP, Macdonald MJ, Hawley JA. Physiological adaptations to low-
volume, high-intensity interval training in health and disease. J Physiol. 2012 Mar

1;590(Pt 5):1077-84.