| By: Kate Underwood
Subaru
Factory Team
Nordic skiing has one of the highest aerobic requirements
of any sport. This sport demands the utilization of nearly
every muscle in the human body and explores terrain and conditions
- brutalizing competitors of the highest physiological caliber.
It is important to remember that we are currently reaching
the upper limits of performance in all sports. We have recorded
endurance capacities in our sport of 96.5 ml/kg/min VO2 and
higher in men and an excess of 80 ml/kg/min for women. We
are nearing the time when we have exhausted most training
methods in both volume and intensity and a mixture of both.
More and more we will look toward the smaller areas of physiology,
training methods and technology for improvements in the next
decade. You can already see this in the research of hyper
baric chambers and the close monitoring of blood chemistry.
The future is uncertain in the areas of training methods
and what will help athletes excel in the next decade. The
present train of thought is in the area of neuromuscular training,
or the training of the central nervous and muscle systems
and they can function together under the levels of high fatigue.
We know at this time that when we are at this high fatigue
level in the late stages of a race our primary muscles (aerobic/slow
twitch) begin to dysfunction, shut down, and subsequently
the athlete slows. This is apparent in the lost meters per
second in timing studies or slower splits on a two-lap course.
It is interesting to understand that in humans, it is always
the peripheral system (muscle) that fails first under extreme
fatigue. The central system (heart and lungs) fails thereafter.
It is at this point of demise that our primary muscles and
the oxidative slow twitch muscles (OST) diminish in performance,
force, work output, cycle rate, and all measurable parameters.
We hang on and fight to the finish. Certainly this is the
point at which most races are won and lost.
It is also during this stage of decreased function that we
attempt to recruit other muscle fibers. First we engage the
fast twitch oxidative muscles (FTO). These are fibers have
characteristics of both our slow twitch aerobic endurance
muscles and our anaerobic fast twitch muscles. The FTOs are
like our “middle distance muscles” in running
and the ones we condition by doing speed intervals at, above,
and below anaerobic threshold. In distance running we utilize
these muscles when we run at speeds and intensities from 800m
-1500m- 3000m race speeds. In our Nordic training zone levels,
this equates to level 4-5 intensity (on a level 1 to level
5 scale). If we have not trained these muscles, we can use
them, but only for a short time before they also fail us and
our speed, force , cycle rate, etc. slows again.
One of the areas of future development in the increase of
the capacities of Nordic skiers will come in the area of the
recruitment of the pure fast twitch muscles, or the non -oxidative
fast twitch muscles (NOFT). These are our pure fast twitch
sprint muscles. We rarely use NOFTs during longer races so
when we attempt to, they last for an even shorter duration
than the FTO muscles. In our Nordic zone levels, it equates
to level 5 or supra-maximal sprint speeds - or a speed that
corresponds to skiing as fast as is possible while still making
proper biomechanical movements. (During a 30-80 meter sprint,
we engage almost exclusively the NOFT fibers.)
It has been theorized that in an all out 400m running sprint,
we utilize these “exclusively fast twitch” muscles
in the first 20-40meters, (start up speed) and in the last
60- 80 meters (final kick), accounting for only 1/4th the
output of an entire 400m sprint. The rest of the race utilizes
a combination of both the “middle distance muscles”
and “exclusively fast twitch” fibers. These are
associated with the more comfortable zones we train in the
majority of the time (Levels 1-3). These are also the intensities
that we lose as we age.
In the near future, the speeds of sprint skiing will offer
a preview of both the utilization of these muscles and the
associated training methods from this discipline that will
allow long distance skiers to ski faster and faster in all
distances (m/sec). This will be apparent in both in classical
and skating races. It is not unlike the progression of higher
classical speeds in m/sec since the advent of skating technique
(Note: technological innovation shouldn’t be overlooked,
but we’re talking about bodies not skis).
The theory at this time is simply this: If you don’t
train the “exclusively fast twitch” muscles, you
can’t recruit them. When it all starts to fall apart,
they’re not going to come to the rescue. The breakdown
in the neuro-muscular function is the connection between the
nerve impulses, the motor neuron junction (where impulses
actually signal the muscle fibers to contract) and the muscle
fiber. This process is untrained in most endurance athletes
and needs to be trained at much greater levels and with much
more regularity.
These training principles can be applied to athletes of all
levels, whether they are training for a local 5-10k race or
a large 50k ski marathon. Everyone has these muscles, so anyone
can benefit from conditioning them. If you want to improve
these “exclusively fast twitch” muscles you should
be well warmed up, and aim at going in this level 5 for 30-80
meters. Rest is necessary between any fast twitch muscle workouts.
In this case, and in the future, you will see that speed
doesn’t kill. It enables.
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