When lactate production exceeds the rate at which it can be broken down in the cell, the blood lactate concentration grows at a near linear rate until ~4 mmol. From there, all bets are off as exponential growth in the overtaxed muscles floods the bloodstream until lactate can be taken back up by the muscles when at rest.
OBLA is not the lactate threshold
During anaerobic exercise, this onset of blood lactate accumulation (OBLA), is very often conflated with the slightly more familiar lactate threshold. But the lactate inflection point (LIP), is the intensity at which the blood concentration of lactate begins to increase exponentially.
Tiny blood samples are a popular way of measuring lactate blood concentration. However, they are costly and are far more easily collected at rest. So, in lieu of available testing kits, we can anecdotally express it as 85% of maximum heart rate or 75% of VO2 max.
Tools for predicting aerobic capacity and exercise intensities that do not include lactate measurements and the uncertainties it comes with help proliferate the concepts without the additional burden(s).
How does training affect lactate levels?
As blood lactate concentrations increase, performance decreases, and fatigue sets into the muscles. For example, this sensation is when your arms and legs are on fire at the track. Or as your breath speeds up during rest intervals at the swimming pool.
At rest, this effect is the training’s influence upon lactate production because availability depends on the now circulating lactate’s eventual re-uptake into the musculature.
The critical speeds at which you can meet OBLA measure the amount of power or velocity that an athlete can achieve at a given level of training.
The data support the hypothesis that a steady state training intensity which approximates VOBLA will increase VOBLA and will result in measurable local metabolic adaptations in the active skeletal muscles of well-trained runners without a significant change in maximal aerobic power.B Sjödin, et al
Anaerobic threshold (AnT) is sometimes defined equivalently to the lactate threshold (LT). But its contribution to exercise intensity actually becomes less and less a percentage of the overall workload. When blood lactate exponentially increases aerobic metabolism is what keeps athletes moving. Possibly even helping the reuptake of lactate at very low intensities..
Fartlek workouts demonstrate OBLA best
Fartlek and interval training are very similar; the main difference being the structure of the continuous exercise. A Swedish word, Fartlek means ‘speed play’.
This speed play is a combination of long continuous running (generally aerobic), involving consistent changes to the initial pace/intensity (generally anaerobic bursts) throughout the run.
Try out this Fartlek workout from Runner’s World
Fartlek No. 4, Week 4 is the granddaddy of them all and will complete your month of fartlek running prior to hitting the track.
After a warm-up, perform the following surges, all followed by a 2-minute easy jog: 5 minutes, 4 minutes, 3 minutes, 2 minutes and 1 minute.
Your effort should increase as the length of the surge decreases. The 5-minute surge is at 80 percent of full effort. The 4-minute surge is at 85 percent of full effort. The 3-minute surge is at 90 percent of full effort. The 2-minute surge is at roughly 95 percent of full effort and the 1-minute surge is at nearly 100 percent of full effort.
This workout is designed to mimic the increase in effort that you must make in order to race at your highest level for the 5K and 10K distances. Don’t worry about pace or heart rate. Just focus on effort. Learn your body.GREG MCMILLAN
Distance and mid distance workouts performed this way challenge speeds at the maximum lactate steady state (MLSS) and exponential nature of accumulation after OBLA.
Supplementation is another challenge
β-Alanine (βA) has been shown to improve performance. This study was the first to examine the effects of βA on OBLA during incremental treadmill running.
After 28 days of 6.0 g·d-1 of βA supplementation, the βA group had a delay in OBLA as determined by increases in HR@OBLA and %MaxHR@OBLA.
On day 29 (post-supplementation), subjects in the βA group had a significant increase (p = 0.034) in %VO 2max @OBLA while no changes were observed in the PL group.Thomas Jordan, et al
Yet despite superficial positive outcomes, supplementation for performance gains may be a long term loss. Introducing βA into performance, may not allow the body to make the necessary physiological adaptations to the increased workload(s). Albeit neuromuscular changes might. But to perform at the increased levels, athletes would need to continue supplementation during events.
No shortcuts with training adaptations
OBLA has a significant impact on how quickly a person fatigues during sports, how easily they can maintain high training loads, and ultimately affects an athlete’s overall performance. Just please stop with the lactic acid excuses.
In the vast, intricate theatre of the human body, there’s an interlude – not quite discernible at first – where the muscles, those bundles of fibers so dutiful in their contractions and extensions, begin to cry out in a microscopic revolt. It starts with the cells, those tiny diligent workers, finding themselves in an economic downturn of oxygen, the very currency of their effort. With every exertion, they turn increasingly to anaerobic means, a sort of underground and less efficient metabolic economy. And as they do, they produce lactic acid, not out of spite, but as a mere byproduct, like the exhaust from an old car.
This acid doesn’t just sit idly; it accumulates, steadily, like clouds foreshadowing a storm. The muscles, in their ever-loyal duty, attempt to clear this growing debt, but there comes a threshold – a tipping point – where the acid, like a crowd gathering at a protest, becomes palpable. It’s here, in this physiological narrative, that the athlete or the casual jogger or the person late for a bus feels that unmistakable burn. It’s not just pain; it’s a signal, a Morse code of sorts, hinting that the boundaries of endurance are nigh.
But like all things, it’s not merely a matter of chemistry or biology. For in the mind of the one running or cycling or swimming, there’s a dialogue – a negotiation between the desire to press on and the increasing weight of this lactate rebellion. It’s in this space, this liminal zone of effort and exhaustion, that so much of our human story, our will, and our fragility play out.