|
As long as I have been involved in the sport
of cycling (since 1984), base has not carried
this definition. Base has almost always
been defined as something to do with long,
easier rides before higher intensity training or
racing begins, and it has been suggested that
this approach is a prerequisite for future
performance. Some base traditionalists
have been known to prescribe power or heart-rate
ceilings in order to limit training intensity
for many weeks or months during their base
period. The rationale is that this builds
“endurance” and enhances future higher intensity
training. The issue with this more
traditional approach is that endurance is
primarily a function of 20MP, as 20MP influences
nearly every power-duration relationship in
cycling. The primary benefit of long, low
intensity rides is that they train your body to
sit on the bike for longer; however, these
efforts have a limited impact on 20MP, and by
definition, overall cycling performance.
How does 20MP dictate nearly all the
power-duration relationships? There are
two main parts, but they are both connected.
First, intensities above 20MP cannot be
sustained for very long and require recovery
below that intensity to repeat the effort.
Basically, every little bit harder than 20MP an
effort is the shorter the duration that effort
can be sustained. The power-duration
relationships become curvilinear in that the
duration drops exponentially as power rises
above 20MP. Whether climbing in a mountain-bike
race or road race, holding a wheel in a
cross-wind, time-trialing, or positioning for a
sprint, 20MP influences the intensities
sustainable during these efforts and what
capacity is available to launch above it before
failure and necessary recovery. In other
words, the higher the 20MP, the higher the
absolute powers which are sustainable for
durations shorter than 20 minutes up to the
genetic limitations of fiber type and
neuromuscular make-up.
Figure 1. Sample of power-duration
curve.
Second, the duration one can sustain a given
power output below 20MP increases with
decreasing intensity, and this relationship is
rather linear with a shallow slope. In
other words, small drops in power result in
large increases in duration. This is
primarily due to an energy source shift away
from glycogen as intensities decrease below 20MP
(as implied by Holloszy and Coyle, 1984; Coyle
et al. 1988; Romijn et al. 1993).
Generally, more fats are used to generate that
energy and glycogen is spared. Put more
simply, the higher the 20MP, the longer a lower
absolute power can be sustained and the faster a
power relative to 20MP will be. For
example, my 20MP is about 290 watts right now.
For every little bit easier I ride below 290w
the duration I can hold that lower power
increases. If I was to improve my 20MP to
310w, I suddenly would be able to ride at 290w
for a lot longer than 20 minutes. I very
well could ride at 290W for an hour. By
increasing my 20MP, I increase the amount of
time I can spend at every power level below it.
Longer rides are not absolutely necessary for
improvement in power-duration relationships –
improve 20MP and everything else for longer
durations will follow.
These two parts of basically the same principle
illustrate how 20MP strongly influences
power-duration performance. The higher
your 20MP, the more power you can sustain for
nearly every duration attempted (some extremely
short sprint-like efforts may not be changed).
This is one reason why 20MP is the base of
cycling performance.
Traditional base often suggests that there are
unique physiological adaptations which only
occur during slower, longer rides. This is
not the case with the exception of glycogen
storage in the particular muscle fibers used
during these lower power rides. Let’s take
a look at a summary of the primary components
which come together to produce 20MP in order to
illustrate how long, slower rides only have a
limited and secondary role in performance.
20MP is primarily a product of two things:
mitochondrial density or activity and oxygen
delivery. There are other aspects which
affect 20MP such as clearance of metabolic
byproducts, acid tolerance, motor-unit
recruitment patterns, a small “anaerobic” power
component, and the like, but for purposes of
comparison to lower intensity training (and
traditional base definitions), mitochondrial
density and O2 delivery are the most applicable.
Mitochondria are the energy factories of working
muscle cells. Basically, the higher the
mitochondrial density a muscle cell has the more
power it can generate over time.
Mitochondrial markers do not appear to increase
under low intensity conditions very quickly.
They appear to only increase when the rate of
energy demand over time in an individual muscle
fiber outstrips the cellular mitochondrion’s
ability to provide it. The maximum
stimulus for mitochondrial development as a
whole appears to exist at the edge of aerobic
power production or 20MP (as suggested by
Dudley, 1982 and subsequently Terjung, 1995).
When you ride hard enough for long enough such
that the muscle fiber overload is nearly
maximized, it appears that the biochemical
environment is primed for mitochondrial growth –
and this is a good thing. Lower powered
efforts predominantly only use muscle fiber
profiles which have already mostly adapted to
this stimulus in prior training. These
muscle fiber-profiles are already equipped and
respond much slower since as a whole, the
biochemical stimulus for mitochondrial growth is
minimal – one just isn’t going hard enough to be
very productive.
O2 delivery is similar. Vascularity only
adapts if the rate of muscular oxygen demand
increases. Gains in blood-vessel measures
appear to respond similarly to mitochondrial
measures in that it is the rate of oxygen demand
which stimulates the greatest demands for
vascular adaptation as mitochondrial
improvements appear to parallel vascular
improvements (Coggan et al. 1992; Poole, 1996;
Charifi et al. 2004; McAllister et al. 2005).
The heart responds in much the same way.
If the heart is not forced to pump hard and
fast, it is just pumping. Lower
intensities do not provide the same stimulus for
O2 delivery as 20MP focused training.
The biggest decision in training choice and
prescription addresses the cost-benefit
relationship between time and intensity.
Hypothetically, if you trained at lower
intensities for large amounts of time (per
day/week for many weeks) and increased the
training power a few watts every week, you might
eventually reach your genetic limits for O2
delivery and mitochondrial density and therefore
maximize your 20MP. The costs incurred
with this approach are time and the large volume
of overall fatigue caused by exposure to the
weather and the mental and physical stress of
all those endless hours on the bike. This
fatigue can result in immune-system depression,
psychological depression, depression of “good”
hormone levels, and over-use injuries caused by
such huge volumes of repetitive motion to name a
few. These potential liabilities suggest
that this approach may not be worth it,
especially when you can accomplish the same
adaptations in a small fraction of the time.
Why waste your time and incur these significant
costs? Even professional riders do not
have time to waste. Time is better spent riding
harder, recovering sooner, and avoiding
unnecessary fatigue when building your base.
There is a proper application for those longer,
easier rides which shift adaptations towards
glycogen storage in lower powered muscle fiber
profiles, but they are not the base of cycling
performance. 20MP is this base.
|
|
The many variables which compose individual
performance are often hard to learn how to
manage. Proficient management of training
variables requires the incorporation of the
science of physiology, the advances provided in
performance measurement offered by such items as
power meters, and the experienced interpretation
and application of both to performance.
Experience can help direct efforts in the
absence of expensive tools since improving
performance is still all about identifying that
which limits it. This is often the role of
a good coach when combined with the
understanding that the ultimate thing a coach
can do is teach you how to be your own coach.
There is no more powerful a tool than the
super-computers we all have. We can all
use a little more software, but generally, your
super-computer already knows this:
“You have to train hard and rest hard to go your
fastest.”
Happy training and have some fun out there!
That’s really what sport is all about!
Works Cited and Additional Readings:
Charifi N, Kadi F, Feasson L, Costes F, Geyssant
A, Denis C. “Enhancement of microvessel
tortuosity in the vastus lateralis muscle of old
men in response to endurance training.” J
Physiol. 2004 Jan 15; 554 (Pt 2): 559-69.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=14578492
Coggan, Andrew. “Training
and racing with a power meter: an
introduction”. 25 March 2003.
http://www.midweekclub.ca/articles/coggan.pdf
Coggan AR, Spina RJ, King DS, Rogers MA, Brown
M, Nemeth PM, Holloszy JO.“Skeletal muscle
adaptations to endurance training in 60- to
70-yr-old men and women”. J Appl Physiol. 1992
May;72(5):1780-6.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?
cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=1601786
Coyle EF, Coggan AR, Hopper MK, Walters TJ.
“Determinants of endurance in well- trained
cyclists.” J Appl Physiol. 1988 Jun; 64 (6):
2622-30.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=3403447
Dudley GA, Abraham WM, Terjung RL. “Influence of
exercise intensity and duration on biochemical
adaptations in skeletal muscle.” J Appl Physiol.
1982 Oct; 53 (4): 844-50.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=6295989
Holloszy JO, Coyle EF. “Adaptations of skeletal
muscle to endurance exercise and their metabolic
consequences.” J Appl Physiol. 1984
Apr;56(4):831-8.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=6373687
McAllister RM, Jasperse JL, Laughlin MH. “Nonuniform
effects of endurance exercise training on
vasodilation in rat skeletal muscle.” J Appl
Physiol. 2005 Feb;98(2):753-61.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15448126
Poole DC, Mathieu-Costello O. “Relationship
between fiber capillarization and mitochondrial
volume density in control and trained rat soleus
and plantaris muscles.” Microcirculation. 1996
Jun;3(2):175-86
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=8839439
Romijn JA, Coyle EF, Sidossis LS, Gastaldelli A,
Horowitz JF, Endert E, Wolfe RR. “Regulation of
endogenous fat and carbohydrate metabolism in
relation to exercise intensity and duration.” Am
J Physiol. 1993 Sep;265(3 Pt 1):E380-91.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=8214047
Terjung, Ronald L. “Muscle adaptations to
aerobic training.” Gatorade Sports Science
Institute. SSE#54-Volume 8 (1995) Number 1.
http://www.gssiweb.com/reflib/refs/27/d0000000200000068.cfm?pid=87&CFID=1482974&CFTOKEN=75089253
About our Contributor:
Kirk Willett, is a twenty-year+ participant
in the sport of cycling who has competed in 17
different countries on 5 different continents.
Originally from Pullman, Washington, his racing
career has ranged from his roots as a Pacific
Northwest junior and amateur competitor to time
with the U.S. National Team and then on to
professional competition as a member of the
Mercury Cycling Team including events such as
the Tour of Switzerland. He was also a
director with the Mercury Cycling Team and then
directed the Prime Alliance professional team
full-time from 2001 through 2003. He has
also been a coach and advisor to members of both
the Mercury and Prime Alliance professional
teams in addition to other Pacific Northwest
athletes.
Kirk is currently a medical student attending
Oregon Health Sciences University building on his exercise
science education from Washington State
University. He resides in Portland, Oregon
with his wife Tina and two sons. He is a
strong advocate for clean, ethical sport and
encourages all athletes to take the same pledge
he did as a young amateur: “I will never
participate in doping no matter what I stand to
gain.
|
