Yeah I know another training article blah blah blah. Its a good one though. Take your time grab a coffee and read through it. I've highlighted areas I think are quite important
Lactate threshold: its significance and determination via field-test
BY CHARLES HOWE
Imagine yourself on the starting line of an auto race. All cars have identical aerodynamic characteristics (i.e.,
the same body), so you’re wondering what each one has “under the hood.†Now, suppose your own engine is
the most powerful in the race the – it can reach 500 horsepower – but there’s just one problem: when you try to
sustain more than 80% of those 500 horses for a few minutes, a sort of governor kicks in that makes it cut back
until various engine conditions reach a particular operating range. Your principal opponent, on the other hand,
has an engine that can only reach 475 hp maximum – 5% less than yours – but his governor kicks in at 90% of
that, or 428 hp – a full 7% more than you can maintain on a prolonged basis.
The horsepower-governor analogy helps illustrate the relationship between the central and peripheral
determinants of endurance performance, i.e., maximal oxygen uptake (VO2max), and lactate threshold (LT),
respectively:
1. the first sets the upper limit of ATP (adenosine triphosphate) production via aerobic metabolism, and is
determined primarily by cardiac output (CO), the ability of the heart to pump oxygen-carrying blood to
the working muscles; CO in turn depends on cardiac stroke volume (SV): CO = SV × HR (the Fick
equation); ATP is the sole and direct source of energy used by working muscles
2. the latter determines the percentage of VO2max that can be utilized for an extended period (6 minutes or
longer), and correlates with the density of mitochondria (the locus of aerobic ATP production) within the
working muscles, as well as the extent of capillarization present, two adaptations that depend largely on
years of specific endurance training at an adequate intensity
VO2max is determined in a lab by analyzing expired gasses during a “ramped†test on a calibrated ergometer
cycle, wherein increasing work loads are imposed in a specific protocol until exhaustion is reached. LT is
determined along the way, prior to exhaustion, through analysis of blood samples, with the ratio of expired CO2
to inspired O2 (known as respiratory exchange ratio, or RER) being used a check.
On a practical level, the importance of LT is primarily in setting training levels (such as these), as well as gauging pace during intervals
and time trials, however, it need not be determined in a lab; average power over a 40-60 minute test TT, or
“functional threshold power†(FTP), serves well as a “proxy†since it correlates very closely with VO2 at LT
(although power at LT, as determined in the lab, will be somewhat lower than FTP). Such a test gives a “bottom
line†measure that integrates all physiological determinants of endurance performance (VO2max, LT, and
efficiency), and so is an excellent practical alternative to a ramped lab test.
The drawback to functional field testing is that it is self-administered, rather than carried out under the watchful
eye of a coach or exercise physiologist in a lab or other controlled setting, and can therefore be affected by
environmental conditions, the motivation and concentration of the test subject, as well as (to a lesser extent) his
or her judgment and skill in pacing correctly. For consistent and reliable test results, make sure you are
adequately rested, with no illness or infection present, while avoiding extremes of temperature (especially heat)
and wind. Flat terrain is recommended, but a steady, continuous uphill grade can also be used, and even a
rolling to hilly course will do if the same one is used each time (average power on a rolling/hilly course, or in
variably windy conditions, will be somewhat less than for a windless, constant-grade test of similar duration). It
may take a few attempts to get the pacing just right and the wattage “dialed in†(Figure 1), but once it is, average
power achieved in any carefully executed threshold test should be highly repeatable from day-to-day.
(Stu once asked me what would make him stronger so that he could attack again and again. The answer suprisingly is most likely to be in having a higher lactate theshold/greater aerobic power and not necessarily as Paul H's article seems to suggest more anaerobic power - see point 2)
Wide and rapid variation in the energy demands of road cycling has led some, such as Dr. Arnie Baker, M.D., in
Smart Cycling, to conceive of it as an anaerobic sport, but this is contradicted by what is already known:
1. most energy for a single maximal effort over 70 seconds, starting from a rested state, comes from aerobic
sources (Figure 2)
2. in four 30 second bouts of exercise, each separated by complete recovery, most of the energy utilized by
the third bout comes from aerobic sources (Figure 3), and the predominance of aerobic metabolism
becomes even more pronounced during longer exercise bouts (Figure 4), not to mention continuous
exercise, such as any road race, where intensity is lower, and recovery is not nearly as complete
2
3. the extent to which anaerobic energy sources are taxed (and blood lactate is produced) for a given set of
race demands will be determined by how much and often threshold power is exceeded, therefore, the
higher it is, the less they will be called upon, while the more often it is exceeded, the more anaerobic
sources are taxed. Furthermore, within the context of any road (i.e., endurance) event, how quickly one
recovers from short, intense efforts is actually more reflective of aerobic, not anaerobic fitness, since 1)
fatigue during intense exercise is related to changes in high energy phosphate (ATP) levels, 2) 100% of
ATP resynthesis within working muscle occurs via aerobic metabolism, and 3) the rate of ATP
resynthesis is correlated with mitochondrial respiratory capacity
(If you wanna know why time trialist can often do so well in road races (the guy who beat me at Rusper and one the following week is a well known TT strong man, see below)
4. racing categories and time trial performance both correlate much more highly with sustainable threshold
power than with anaerobic capacity or sprinting power.
Thus, it often goes unrecognized that greater aerobic ability (in particular, a high mitochondrial density within
muscle) enhances the ability to sprint or attack in almost all race situations. The reason is that short-term power
production is reduced when the effort is initiated from prior exercise (as opposed to from rest), and this reduction is
in direct proportion to high-energy phosphate levels within the muscle. In other words, the really “strong†riders
seem to be able to attack repeatedly, or when the pace is already very high, and then recover more quickly than
others, largely because their muscles are more aerobically fit, not because they have markedly greater “lactate
tolerance,†and despite the seeming importance of sprinting ability in determining race outcome, it is more the case
that the sprinter with the highest threshold power wins. Adam Myerson, a pro/elite-level field sprinter, summed it
up nicely by noting that sprinting ability may be what helps you win the game (race), but having a high threshold
power is what allows you to play the game in the first place, and influences how well you can play at the end.
Another insightful comment was recently offered by Andy Birko at Wattage Forum:
(here's one for sprinters without sustainable power. I bet if you tested Adam it would be his aerobic power that had made the most significant gains oin the last 18 months rather than his anaerobic power or sprinting prowess)
[color=#0080BF]“When rested, I’ve got a pretty decent sprint (for a Cat. 4) at around 1100 Watts or so. When I hide, suck
wheel, etc., in a long race, I can produce about 800 Watts or so in the final sprint. When I’m pulling, chasing
etc., I’m lucky if I can hit 650 Watts by the end. There’s another guy in my club whose sprint speed is about
the same as mine (I don’t know his power), and when we do sprint drills, the result is split about 50/50. When
we do our monthly time trial, he goes about 10 seconds faster on his road bike than I do on my TT bike.
Guess who beats whom more often when we do our training races.
Anaerobic capacity is like a bank – every time you go over LT, you’re drawing from the bank, and again,
the further and longer you go above LT, the quicker you’re withdrawing. You can only replenish the bank
when below LT, so recovery from anaerobic efforts is directly related to how often and how much you go
above LT, as well as long you stay there, so the higher your LT, the stronger your anaerobic efforts can be
without draining the bank as much.â€[/color]
This interpretation is spot-on, and is essentially the same as what was presented in a recent study in the Journal
of Applied Physiology. It explains why “genetic sprinters†need to be careful to “conserve their sprintâ€
throughout most any road race; as Jim Martin (masters national match sprint champion, but only a Cat. 3 on the
road) describes it: “I often to spend the whole race sitting in and suffering, waiting for the 1 km to go sign.â€
Further, world and Olympic match sprint champion Marty Nothstein is generally unable to contest for the win
once the ‘smack’ really starts to go down in national-level points races and Madisons on the track, as well as
road criteriums; despite his world-class sprint ability, and even though he has greatly improved his aerobic
ability (threshold power), as evidenced by his win at the 2003 New York City Championship (a 100 km
criterium), it still apparently is not enough to handle the repeated surges thrown at him by riders such as Colby
Pearce, Jame Carney, etc. Even for a points racer, most training time should be spent working on threshold
power, although the new rule awarding 20 points – but no other benefit – for lapping the field tends to tip the
balance a bit more towards those who can sprint well.
Or in other words, it’s an aerobic sport, damn it!
Charles Howe is neither an exercise physiologist nor a USA CyclingTM licensed coach, but you can learn a fair
amount by hanging around the right people. Special thanks to Andrew Coggan, Ph.D., for his contributions to
this article.[/color][/size]