1. The Overload Principle
The Cells are Sensitive
We are biological organisms composed of an interdependent assortment of billions of individual cells. It has been said
that "every cell in our body is psychological". This may sound crazy, but in a sense it is true. Every cell is in some form
or another sensitive to certain forms of stress, and capable of initiating a specific response.
Training is a cyclical process of tearing down and building up
Part of understanding this overload principle is knowing that the adaptations we are trying to stimulate require sysnthesis
of new biological material. This is a process that takes time! Even as you sit reading, your body is constantly in a state
of deterioration and repair. Some cells, like red blood cells are dying out completely at the rate of 2-3 milllion every second,
and being replaced just as fast! Others, like muscle cells, hang around much longer, but are constantly repairing themselves
from within. When we train, we do additional, specific damage to some cells, and use up cellular resources (fuel, water, salts
for example). When you walk off the track or get out of the pool after a workout, you are WEAKER, not stronger. How much weaker
depends on the severity of the exercise stress. The cells always seek to maintain homeostasis, or the status quo, so
the cellular and systemic stress of exercise elicits not just a repair to former levels, but an adjustment or buildup of the
stressed system that serves to minimize the future impact of the stressor. For example, the depletion of muscle glycogen to
low levels by a lengthy exercise session triggers a rebound increase in glycogen storage level. The loss of salts in the sweat
on the first hot Summer day initiates a process of adaptation whereby we eventually sweat more but lose less salt. This GENERAL
ADAPTATION SYNDROME was described by Hans Selye, and expanded by Yakovlev. If the stress is too small in either intensity
or duration, little or no adaptation growth is stimulated. But, if the stress is too severe, "growth" is delayed or even prevented.
Maintaining homeostasis in the face of chronic stress means increasing the synthesis of specific proteins (mitochondrial
enzymes for example) that enable the cell to respond to future demands with less disruption. The optimal training program
would be one that maximally stimulated these positive adaptations, while minimizing the cellular and systemic stress thrown
at the body in order to trigger the changes. Very hard training does damage and sometimes threatens our health by transiently
lowering our resistance to infection. Not to mention the fact that it can stress our time schedules and relationships. Put
in real world training terms, we should try to do the least training possible that still achieves the desired results. This
program would then incorporate the appropriate recovery time; 1) long enough to allow the synthetic processes
time to occur, while 2) not so long that reversion back towards the previous cellular state could begin. Finally. our
overall training program would have to recognize that some cellular adaptations have a faster response time than others. For
example, plasma volume increases dramatically within a week of hard training, while capillary growth occurs slowly years of
training. This knowledge will impact the relative amount of training we dedicate to achieving specific adaptations.
Thresholds and Diminishing Returns
If we put this Overload Principle into action, we are talking about exercise. When we train, we choose some specific intensity
and duration of effort (or sometimes IT chooses us!). Then we repeat these efforts with some specific frequency.
Add in the mode(s) of exercise and you have a training program. Since even the most untrained body has a built reserve
capacity to handle a substantial degree of stress, there is a minimum threshold for intensity and duration of stress that
must be exceeded before additional adaptations are triggered. This is the minimum training threshold. For example,
in untrained people starting an exercise program, we do not see significant improvements in exercise capacity unless the training
intensity exceeds 50% of their maximal oxygen consumption, but this isn't too difficult to achieve. If you have been doing
nothing, almost anything helps. However, this threshold level increases as we become more fit. In elite young and older
athletes, the threshold for a positive training response may exceed 80% of VO2 max. So does this mean that
every training session should be above this intensity? No, this is an important lesson to learn, usually discovered after
repeated injuries, overtraining, and staleness. Exercise at below the higher training threshold can be important for maintaining
existing adaptations while allowing growth processes to occur. What we are faced with as we continue training is
a diminishing return on our training investment. The better adapted we are to exercise, the more difficult it is to
induce further positive changes. Emerging from this fact is the use of periodization of training, a phrase which is
rampant in the literature these days. At the elite level the diminishing returns on training investment are clearly evident
as athletes train 3 hours per day in order to be 1/2 of one percent faster than if they trained 1.5 hours per day, assuming
they stay healthy! So, we each have to decide how important that last 0.5 percent is to us.
2. The Principle of Specificity
I think it is safe to say that the media and shoe makers have combined to confuse many young and older athletes about the
Principle of Specificity. Nike, and all the folks who sell exercise equipment would like you to believe that "Cross-training"
is a key to peak performance. The concept sells more sports shoes and exercise machines, but is it true? Well, no. Any sport
you pursue places highly specific demands on your body in at least two major ways. First, the exercise will have a very
specific pattern of joint and muscle coordination. For a rower, there is absolutely no substitute for rowing. Ditto for
swimming. Even when we try to duplicate the basic movement of a sports skill with strength training exercises, the transfer
of increased strength to the actual sports movement is often small or absent. In the worst case this type of training can
detract from performance of the real skill due to disruption of technique. Second, the exercise will place high metabolic
demands on a very specific group of muscles. For example, running and cross-country skiing appear to involve many of the
same muscles, used in a similar movement pattern. Yet, several research studies have demonstrated that there is NO relationship
between VO2 max measured by treadmill running and VO2 max measured by cross country skiing in a group
of elite-trained skiers. In contrast, there is a strong relationship between on snow skiing and performance on a skiing specific
test such as the douple poling test.
A high endurance capacity in a specific sport requires both 1) high oxygen delivery (cardiac output) and 2) high local
blood flow and mitochondrial density in the precise muscles used. The only way to optimally develop the second component
of endurance is to train those exact muscles by doing your sport!
Is there ever a place for cross training?
The answer to that question is definitely yes! BUT, we need to understand as athletes what the limited purpose and value
of the alternate exercise mode is. For example, I am a rower by choice. That is the sport I compete in. During the Spring
and Summer back in Austin, Texas , 90% of my endurance training was performed on the water, rowing. However, in the late Fall
and Winter (non-competitve period), I rowed less on the water than I could have (No ice in Austin), probably half as much.
Why? Mostly because I was mentally tired of rowing, but also because of the weather and time constraints. Sometimes I would
row on the indoor machine, by no means a perfect substitute for the technique of rowing, but a good simulation for developing
basic rowing endurance. But to be honest, on most days, I hate being on that machine for more than about 30 minutes. Embracing
the expression "the mind needs rest, but the body needs work", I would often mix in running or cycling on an ergometer with
my rowing to increase my total aerobic exercise volume without growing mentally stale. A little bit of cross-training helped
maintain my general aerobic base, while allowing me to mentally recharge my batteries in anticipation of another cycle of
intense training on the water with my rowing partners. Even when I was running or cycling, I knew that it would be the quality
and quantity of rowing that would win or lose upcoming races.
Another reason to "cross-train" is to avoid injury and maintain muscular balance DURING a period of intense sport specific
training. One of the keys to success in sport is staying healthy over the long haul. Weight training by itself will almost
certainly do nothing for a runner's 10k time, but if weight training maintains muscular balance in her abdominal wall and
low back, preventing injury, then it is contributing to her becoming a faster runner. Why? Because it keeps her running! And,
cycling isn't running. But if cycling takes the pressure off tired knees and hips on a recovery steady-state day, then it
will probably make the next running workout better. Cross training should always be limited to those activities that allow
us to do our event-specific training workouts with greater enthusiasm and intensity, or less risk of injury. It is a cautiously
administered supplement, not a substitute!
3. The Reversibility Principle
If people were as economical as their bodies, we would not have problems with personal debt and excess world waste production.
The human body is nothing if not thrifty! The iron and protein in those millions of blood cells that die each day is almost
completely re-used to build new blood cells! The body does not build proteins it doesn't need (except maybe those that make
up the Appendix?), and it doesn't retain proteins that are no longer needed! For the athlete, the unfortunate consquence of
this thriftiness is the rapid reversibility of training adaptations if training is stopped. But of course, you already knew
this. You might not know some of the details like: How rapid? Which adaptations deteriorate the fastest? Does it make a difference
if I have been training for years? What about reducing training level but not stopping? There are so many important questions
on the topic of "detraining" that I will examine them in a separate article.
4. The Principle of Individual Differences
Last but not least on the list of Training Principles is the Principle of Individual Differences.
We All Start Somewhere....different
It is usually practical to describe physical characteristics based on some AVERAGE. On average, American men are currently
5' 9" (1.75 m) tall and about 170 pounds (77kg). But, walk down a busy street and you will see that there is considerable
variability! It shouldn't be too surprising that there is also a lot of variability in our internal charactersitics. Heart
size, muscle mass, bone diameter, fiber type composition, position of mucle attachments on bone, fat distribution pattern,
joint flexibility etc. all vary from individual to individual. Two examples: On average, a 25 year old untrained man
will have a maximal oxygen consumption of 45 ml/min/kg. However, there are completely untrained people that have walked into
a lab, got on a treadmill and had a VO2 max of 70 ml/min/kg. I tested a fellow exactly like this myself once. I
was teaching a class and he "volunteered" to perform a cycling max test. I predicted his max for the class based on his exercise
history (little if any). Imaging my surprise as his VO2 kept climbing and climbing as I increased the workload
on the bike! He didn't bother to tell me his sister had rowed in the Olympics until after the test! There are equally "healthy"
untrained young men whose max is only 35 ml/min/kg. That's a 2X difference in aerobic capacity before they do the first workout!
This is a physiological gap that will not be closed, no matter how hard the "less endowed" fellow trains. If the high VO2
guy trains very hard, he might reach 80 ml/kg/min, a 14% increase. The low VO2 guy can train equally hard
and possibly reach 50 ml/kg/min, a larger 42% increase. The gap can narrow (to 60% here), but it will not go away. Genetics
place limitations on our body.
Example number two: On average, the fiber type distribution in the thigh muscles of a male (or female) is roughly
50% slow and 50% fast fibers. However, in a study by Simoneau et al, 1989, muscle biopsies from the vastus lateralis (outside
thigh) of 418 males and females revealed a range of from 15% slow fibers to 85% slow fibers in different people. Coefficients
of variation approached 30%. Again we see that there is considerable genetic variation in a variable that has significant
impact on performance. So, we each have to focus on approaching the outer boundaries of OUR OWN physical potential.
Different Strokes for Different Folks
At the Laval University in Canada, the University of Texas at Austin, and three other Universities in the United States,
a major collaborative project is currently underway to determine the role of genetic variability associated with individual
responses to an identical training program. Fittingly, this project is called the Heritage Study. Millions of dollars are
being spent to quantify and understand the genetic foundations of a phenomenom that athletes already know full well. We
all respond differently to a training program. Some athletes can do next to nothing 3 months then train like a madman,
sweat, and spew chunks for three weeks and be in racing shape (ok, maybe too graphic). Others are "hard gainers" that seem
to lose everything if they miss a week of training. From numerous research studies involving untrained people starting an
endurance training program, it is clear the On Average, 3 months of regular endurance exercise of appropriate intensity
and duration will result in a 15-20% increase in maximal oxygen consumption, in people with typical VO2 max values.
But what these results do not say is one or two among each of those groups increased only 3 or 4% and one or two others increased
35%, despite identical training!
Some people tolerate and even thrive on, a high volume of training to reach peak fitness. Others cannot tolerate the same
workload, but reach similar performance levels if they intersperse more rest days. We each have a unique psychological makeup.
We have different strengths and "weaknesses" within our physiological performance machine that should influence training plan
design, and we have different hormonal and immune reactivity that will influence the level of stress we can tolerate and improve
under. In the field of exercise physiology, we have learned a great deal about physiological adaptations and the general methods
of training that conform to known physiology. This is very valuable information for the athlete to understand whether 24 or
64 (Of course I am biased on that score). But, remember, ANY exact training program that you copy from me or someone else
is destined to be, at best an approximation of what will work best for you, and at worst, a total failure.
The Bottom Line
Ok, you love your sport and are motivated to improve, but with so many possible training methods and "experts", What can
you do? Well, here is what I think.
First, understand what training does to your body Learn the physiology of the sport (hopefully the MAPP will help).
Know how your engine works. This will help you critically evaluate the disparate training ideas that are thrown your way.
Next, examine and learn the biomechanical principles that must be obeyed for performance success. How do you maximize
the efficiency of transfer of your engine power to performance velocity? There is no endurance sport that does not place a
premium on good technique.
Finally, keep a record of what you do! Use a notebook and pencil, or a fancy computer program, but make yourself
accountable to both the training you do in pursuit of your performance goals, and the results. If you do this, eventually
you will have arrived at your own personal prescription for success, built from solid general principles, but fine tuned to
your personal characteristics. "Success" will vary for each of you in absolute terms; completing a 10k, a new personal best,
a city championship, or maybe a world veteran's record! But it all feels the same to the person who establishes the goal,
develops a plan, and works diligently to achieve it!
