Off Season Intervention (Part I): Fitness is in Your Muscles,
not the Cardiovascular System!
By Rich Strauss
11 Nov 2008
We have bad news and good news for you. The bad news is that
once you
finish this article, you are going to want to cancel that winter
schedule of base building, aerobic mileage-oriented, zone 1-2 training.
The good news is that by the time you finish reading, you’ll be ready
to set up your best triathlon season yet!
Before we begin, a warning: What you are about to read goes against
every single email newsletter or training article that will hit your
inbox between now and January. The “Go Slower to Get Faster” off-season
theme not only makes zero physiological sense, it’s utterly wrong.
Recycled year after year by the latest coach of the month trying to
make a name for him/herself, these ideas have become woven into the
cultural fabric of our sport.
At Endurance Nation (www.endurancenation.us), we are changing the
triathlon game by focusing exclusively on age-group triathlon training
that leads to measurable, quantifiable results. What you are about to
read is the foundation of our approach to training and exactly what led
to 82 athletes in fall of 2007 to, in just 16 weeks, improve their 10k
times by an average of 2:30, improve upon their previous half marathon
best by 4:47 and boost their power on the bike by an average of 15%.
Fitness is in the muscles, not the cardiovascular system.
In other words, running with a higher heart rate doesn’t make you
faster, it just means you have a higher heart rate while running.
Running faster by working harder is what makes you faster. If you want
to run, bike or swim faster next racing season, you will need to run,
bike (or swim) faster in training. By putting the focus on the muscles
(which we control) vs. heart rate (which is out of our control) we add
a new level of awareness and agency to our training. Let’s take a
closer look at how muscles power our exercise.
We control the force of muscle contractions primarily by recruiting and
using more motor units. Small-force contractions use fewer motor units.
In order to produce more force, we begin to recruit more motor units.
Motor units are called into action based on what is called the "size
principle." According to the size principal, low force contractions
recruit small, mainly slow twitch motor units. Higher force
contractions recruit mainly large, fast-twitch motor units. As the
force requirement increases, the motor units recruited get larger and
more fast-twitch. For example, high force activities such as jumping or
sprinting will recruit primarily large, fast-twitch motor units. Lower
force activities such as a slow jog will recruit primarily smaller,
slow-twitch motor units. As we move from jogging slowly to running
faster, we begin to recruit larger, fast-twitch motor units.
Here’s a real-world example to make things clearer: Imagine that you
are doing a graded exercise test on a treadmill or exercise bike.
During a graded exercise test, the exercise intensity is increased
every minute going from very light to maximal effort. At the start, you
begin to engage slow-twitch muscle fibers, using primarily fat as fuel
and no lactate is produced. As the intensity increases, you begin to
engage some intermediate fibers and just a few fast-twitch fibers (as
well as the already active slow-twitch fibers). You have activated a
few fast-twitch fibers, producing some lactate. However, because you
are not producing much lactate, and your slow-twitch fibers can consume
lactate as a source of fuel, lactate levels do not increase
significantly. As the intensity increases further, you begin to
activate additional fast-twitch fibers. They produce lactate and
consume carbohydrates primarily.
Eventually you will reach an exercise intensity that results in more
lactate production than your slow-twitch fibers can clear. This point
is called the lactate threshold and it is marked by a rise in the level
of blood lactate. Lactate accumulation can contribute to fatigue
because it can reduce the capability of muscles to produce force (by
inhibiting anaerobic glycolytic pathways). Therefore, we can exercise
at intensities just below our lactate threshold for quite a while, but
we fatigue quickly at intensities above our lactate threshold.
A few critical things to point out:
• Aerobic vs. Anaerobic exercise. Note that the body moves in and out
of different energy-producing systems as more and different types of
motor units are recruited to do more work. This does not happen at some
definitive line, such as under this line equals 100% aerobic, but cross
that line and it's 100% anaerobic.
• At lower intensities we are only training the muscles we are
recruiting. By exercising at higher intensities, we recruit a higher
percentage of both our slow- and fast-twitch fibers, forcing them all
to adapt. At higher intensity levels we get all of the "go longer"
adaptations we want from the slow-twitch fibers, while also accruing
the "get faster" adaptations from our fast-twitch fibers. If you want
to ride fast, you have to ride fast. If all you do is ride slow, you'll
get very good at riding very slowly!
• Lactate threshold is nothing more than a reasonably identifiable
blood marker at which we can infer that we've recruited nearly 100% of
our slow-twitch fibers, as well as lots of fast-twitch fibers. We sit
on this threshold because it is just that: a threshold. You can sit
right there for a long time, forcing lots of good changes in your
muscles. Too far under LT and you don't recruit enough motor units. Too
far above LT and you can't sit there long enough. Just at or just under
LT is optimal.
But what about cardiovascular fitness, the Training Article Flavor of
the Month from October through January, you ask? Cardiovascular fitness
is actually adaptations occurring in three areas: blood volume, heart
stroke volume, and an increase in blood capillaries.
• Blood volume increases rapidly with an endurance training
program—sometimes by as much as 8% in the first week. In general,
trained athletes can have a blood volume that is 25% higher than
untrained individuals. While the initial increase is often blood
plasma, the red blood cell mass eventually increases as well. This
general adaptation occurs no matter what mode of endurance training is
employed.
• Heart stroke volume increases (or the amount of blood pumped by the
heart with each beat) as you become more fit. While part of this is due
to the increased blood volume, the left ventricle chamber also enlarges
(holds more blood), resistance to blood flow decreases, and more blood
is returned to the heart to be pumped. All of these adaptations occur
simultaneously, which means you are capable of pumping more blood at
maximal exercise levels. These changes can occur rapidly, especially
with high-intensity interval training.
• Muscle capillaries increase—capillaries are the small blood vessels
that deliver blood containing oxygen and fuel to your muscles.
Obviously, more capillaries mean greater blood delivery, which is a
desirable adaptation. During exercise, waste products and other
substances enter the capillaries and trigger expansion. This occurs
only in the muscles that are active during the exercise session,
regardless of exercise intensity. It is true that longer sessions
result in a stronger stimulus for capillary growth as the stimulus is
present for a longer period of time. However, short and hard sessions
provide a stimulus for this type of adaptation as well and certainly do
not reverse this adaptation, as some have claimed. In fact, the only
way to increase capillary density in and around your fast-twitch fibers
is to recruit them with harder efforts.
Think of these adaptations as reworking the plumbing in your body to
deliver more blood, and therefore oxygen and nutrients, to working
muscles. These adaptations happen very quickly and once they are
complete it is still the muscles doing the work. Therefore, the
composition and work capacity of our muscles is the limiter, not the
plumbing. At every distance that you might race as a triathlete, from
sprint to Ironman, you have plenty of cardiovascular capacity left,
even if you are pushing very hard. Therefore, cardiovascular
adaptations are not an important training consideration as far as
performance is concerned.
To summarize the science-speak:
• Most of what we call fitness is the expression of adaptations that
occur in the muscles.
• Contrary to popular/cultural belief, cardiovascular adaptations are a
relatively small and easy to achieve component of fitness.
• By exercising at all intensities, but especially at higher
intensities, we recruit all of our muscle fibers, forcing them all to
adapt so they all become better and stronger at what they do.
Train Faster to Get Faster
So what does this science-speak mean for you?
• “A rising tide lifts all boats.” By training at threshold, we come
faster at threshold. You used to be able to ride one hour at 18mph and
noodle at 16mph. Now you can hold 20mph for an hour and 18mph is the
new noodle. How do you have develop the ability to ride 18mph for 6hrs+
on race day? Well, we can tell you that no amount of riding at 16mph is
gonna get you there! You build the 18mph Noodle Fitness by riding at
20mph+ a lot! Train faster to get faster!
• Farther + Faster = Disaster. Tradition training approaches tell you
to build the aerobic engine, and then make it faster closer to the
race. Our experience, with our own training and across hundreds of
athletes, has told us that, yes, it makes sense that closer to the race
we want to focus on race-specificity: effort, position, nutrition, etc.
We want to get very good at doing the “stuff” we will do on race day so
training at an aerobic intensity during the race build makes sense
because it’s race-specific. However, traditional training tells you
this is also the time to build your Fast, after you’ve earned the right
by building a bigger engine. But this intensity on top of peak weekly
training hours is a recipe for over-training, injury and burnout. The
net is that “get faster” never happens under the traditional approach
because, right when you’re supposed to get faster, the race says you
also have to go longer and something just has to give.
• Instead we build your Fast, in the Off-Season, when there is no
requirement to also build Far.
• Finally, on a real-world level, we do this harder/faster work in the
off-season because we have plenty of time to recover, we don’t have to
compete with races (build / taper / recover), for most of us it’s cold
and dark outside, and going long at the start of a long season would
just make us nuts. In other words, it just makes sense.
As you consider your approach to off-season training this Fall/Winter,
we suggest you think long and hard about…not going longer, but going
harder. Not only will it rejuvenate your focus, it will set you up for
a great season. Good luck!
XTri
RunCoach
