---- Research Corner ----
Lactate Threshold
What's it all about?
Research says...
Lactate is produced as a side reaction in
a metabolic process called glycolosis. Glycolosis is the body's energy system that breaks down
carbohydrates (glucose) that are stored in muscle and liver to produce
energy. Lactate IS NOT the cause of acidosis - that burning sensation
your feel in the muscle - but
rather it is the byproduct of glucose breakdown during intense exercise. So
lactate is actually an indirect measure of acidosis or muscle fatigue.1
Your Lactate Threshold (LT) is a marker
showing how much exercise (or physical work) you can sustain before the evidences of glycolosis
are present. More specifically LT is that point in your exercise
level where you begin to accumulate lactate in the blood and breathing becomes
noticeably more labored (ventilatory changes). LT usually corresponds to a
15K running pace or a 30-40 minute time trial on a road bike.
Your LT can be evaluated by
several methods that include monitoring your heart rate, oxygen consumption and Power output or speed at LT. With appropriate training
technique you can increase
your LT which will enhance your body's ability to increase energy production
through mitochondrial respirations ( or more aerobic pathways) thus decreasing the
reliance on energy from glycolosis (anaerobic). Which means you can spare your
glycogen (ie., your stored carbohydrates) which are in limited supply
compared to the large amount of energy you have available from fat storage.
Additionally, smart endurance training will improve
your acidosis-buffering effect, thereby decreasing fatigue allowing for a
longer tolerance of challenging workouts and an enhanced training effect
allowing for even more intense training.
Here are some the recommendations from the literature on how to improve your
LT:
-
An intense workout that is slightly above
the LT is considered by some researchers to be the best for boosting LT
2
-
20 minutes or more of training at a HR
just above the LT is enough to significantly increase LT 3
-
LT tends to be higher in older runners
with one study showing the average LT at 85% of MaxVO2 for older runners
and 79% for younger. Keep in mind that MaxVO2 scores are lower in the
older athletes since they tend to decline with age. 4
-
Research suggests that training
programs that are a combination of high volume, interval and steady-state
workouts have the most pronounced effect on lactate threshold improvement.
5
Further applications:
Knowing your heart rate at LT allows the
heart rates of other training zones to be calculated. For example, base
endurance training (the longer slower training in zone 2) is typically 90-95% of your
LT heart rate and the harder LT interval training in zone 4 is about 105% of LT
while tempo training workouts are usually right around LT. The
prescription of training using individual heart rate zones based on the LT
heart rate (from exercise testing) can have a profoundly beneficial effect on
training adaptation.
Retesting: If training goes well and the
HR prescription proves to be ideal for moving the threshold higher (to the
right) then the program is working. If however, the results are not as
effective as planned then modifications in the training plan would be
warranted.
1. Robergs, R.A. Ghiasvand, F., & Parker,
D. 2004. Biochemistry of exercise-induced metabolic acidosis. American
Journal of Physiology - Regulatory, Integrative and Comparative Physiology,
287, R502-16.
2. Increased Training Intensity Effect on
Plasma Lactate, Ventilatory Threshold, and Endurance.". Medicine an Science
in Sports and Exercise, Vol 21 (5), pp 563-568, 1989.
3. Changes in Onset of Blood Lactate
Accumulation (OBLA) and Muscle Enzymes after Training at OBLA, European
Journal of Applied Physiology, Vol 49, pp 45-57, 1982
4. Lactate Threshold and Distance Running
Performance in Young and Older Endurance Athletes," Journal of Applied
Physiology, Vol 58(4) pp 1281-1284, 1985
5. Robergs, R.A. , & Roberts, S. 1997.
Exercise Physiology: Exercise , Performance, and Clinical Applications, St.
Louis, MO: Mosby
The information and programs are for informational purposes only. They do
not substitute for the advice of a qualified health care professional or
physician.
The Fit Stop Human
Performance & Health Enhancement Lab, 2006
'
(760) 634-5169
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kjnico@fitstop-lab.com