This is a great article which clears a lot of misconceptions about “threshold” training. Click here to read the full article or read through the highlights below.
Where does the lactic acid theory come from?
The acid theory held sway from an early “frog’s-legs” experiment before the First World War. Voltage was applied to dissected frog’s legs, and ph measurements were taken until the muscle fatigued. The ph at the end of the experiment was much lower than the start, showing presumed “lactic acidosis”.
The conclusion was that acid was the cause of fatigue, and the acid was present due to the lack of oxygen to transport it away. The lack of oxygen was probably due to the lack of a body (and lungs) being attached to the legs! It took the Lactate Shuttle work of George Brooks and his discoveries (see end of this article), from the 1970′s up until today, to change the world’s understanding of lactate physiology.
So what does happen?
Unsurprisingly, your body doesn’t work like this. Lactate accumulation, during increasing exercise intensity, is a constantly rising continuum. But lactate isn’t just exercise induced. You always have some (even now while reading this), you just get more of it when you exercise and when you exercise even harder, you get even more.
While we’re at it, let’s clear up another confusion. It’s not Lactic Acid! Lactic Acid is a neutralizing food additive that is produced from sour milk and used in bakery products, cheeses, frozen desserts, jams and jellies to name but a few. It won’t make you go faster. It just makes food taste nice. Lactate, is lactic acid minus a proton.
Many people use the term lactic to describe lactate. It’s like using the term him and her for humans. Yes, we’re all human but as you know there is a world of difference between men and women! Well lactic and lactate are just like men and women. Similar but different.
Lactate is a by-product, not a waste product, of exercising. It should be seen as your friend not your enemy. Although, as with all things in life, everything in moderation.
Lactate is an output of anaerobic exercise and an input for aerobic exercise. When you ride within the grey area that’s the boundary of both, you’re potentially in to a free ride. The person that maximises their wattage at this boundary point is on to a winner. Quite literally.
If you can produce the same or more power with less resultant lactate, you’re becoming much more efficient as a cyclist. Cycling is an endurance sport and efficiency is key to conserving your valuable energy resources. No use being the best sprinter in the race if you’re not there at the end to use it.
At the point just before the Onset of Blood Lactate Accumulation is the Maximum Lactate Steady State level. This is the point you want to move up your power and speed, and down your heart rate, scale. Measure your OBLA, train to improve your MLSS, go off and win some time trials, stay away in a break, or climb like a god.
Some added points
If you want a real live example of how this works then we should look no further than the world of IronMan athletes (like riding partner Richard Davy on the right) and marathon runners. I’m sure you’ve seen the scenes at the end of the London Marathon or an IronMan event when the skinny leaders come across the line utterly exhausted.
Well here’s a surprise for you. Their lactate measurements at the end of the event are stupidly low. The good ones cruise at 1 mmol above their baseline for the majority of the event. And ramp up to their maximum lactate steady state level as the race moves on. And for the swim and run they haven’t even got a power meter!
These top athletes run right on the edge of their MLSS, remaining aerobic, using predominantly fat for fuel, saving carbs and recycling their pyruvate to get their race winning fuel for free. When did you last see a marathon runner throwing a load of power bars and gels down their throat in a race?
We all try to race like a 100 metre sprinter. We should be thinking with an ultra-endurance athlete’s mindset if we want to be more successful in our quest for greatness. At least for 99.9% of our chosen event.
Why the hell do my legs hurt?!
The burning in your legs is caused by muscle polar and de-polarisation! It’s to do with ionisation not acid.
The Cori Cycle
The Cori Cycle is a training partner of the Lactate Shuttle. It has a different function but it’s complimentary to your understanding of lactate and going faster.
The Cori Cycle describes the metabolic pathway that uses our blood to transport the energy by-product lactate to the processing marvel that is our liver.
Once in the liver, the lactate is converted to glycogen, then to glucose through a process called gluconeogenesis. The blood is then used to transport the glucose back to the muscles. Once in the muscle it converts back to glycogen for fuel, is used and if you’re still going flat out is converted back to lactate. Simple!
This process cannot be sustained indefinitely. You don’t get something for nothing in this world; there’s a price to pay for everything.
The liver cleverly attaches two stored ATP molecules to the incoming lactate to change it to outgoing glycogen. But it costs the liver six ATP molecules to be able to do this. So the liver suffers a four molecule deficit for each “upgrade” it carries out.
Sooner or later (around 30 minutes depending on pre-event hydration and fuelling levels) the energy giving stocks will be exhausted. When that happens, you bonk, you stop.
The only way to get back in to ATP credit is to back off the intensity until you reach a level of positive balance. From there, you have to surf the wave that is lactate balance if you want to get to the end of the day before the time cut-off.
