Apnea

What We SAID

In exercise science, there’s a principle known as SAID, or ‘specific adaptation to imposed demands’: when your body is exposed to a stress, it responds by improving your biomechanical and neurological ability to handle that stress. 

Start doing pull-ups regularly, and your body will get better at pull-ups, increasing the strength in your lats and biceps, and reinforcing the tendons in your shoulders and elbows.

But SAID also dictates that adaptation is specific. So while practicing pull-ups will make you better at pull-ups, it won’t necessarily improve your ability to pull yourself up a mountain face while rock-climbing.

For years, the gospel of SAID kept most athletes locked into the most literal version of their sport. If you wanted to train for a marathon, you’d simply go for increasingly long runs.

Let Us Be (Less) Specific

Over time, however, scientists began to discover that adaptation wasn’t quite as specific as initially believed. Because most sports depend on a constellation of intertwined skills and abilities, other types of training could often develop those constituent skills and abilities more effectively than simply (or solely) practicing the goal sport itself. 

Rather than just going for long runs, for example, marathoners began to integrate interval and tempo work – practicing the skill of running faster for short distances, and then working on sustaining a higher pace for gradually greater distances. Though neither type of run was as ‘specific’ as a long-distance jog, they helped runners improve faster than long-distance jogging alone, and athletes began to set new records, year after year.

As athletes and coaches further experimented, they began to see that even more distantly-related variants of the initial task could be valuable. In the early days of the competitive marathon, for example, weight-training was considered anathema to running. By now, virtually all marathoners have extensive weight-lifting programs. And the details of those programs have evolved over time, too. While runners initially used light weights for a large number of reps (reasoning that it more closely mirrored the endurance-heavy nature of the goal task), now elite runners instead tend to focus on developing skills like power-endurance in the weight room. Though a heavy set of cleans is a far cry from a long-distance jog, it turns out to pay greater dividends on the road than time spent doing multiple sets of 20-rep leg extensions.

Far, Far Away

Today, some of high-level athletes’ training modalities seem ridiculously distant from the sort of specific training that once dominated the show. For example, hyperthermic conditioning – or, sitting in a sauna or steam room – has recently come into vogue. Scientists discovered that regular time in the sauna boosts plasma volume and blood flow to your heart and muscles, increasing endurance in even highly-trained athletes.

In other words, while adaptation may be specific, a modern and science-based understanding of training has a much broader definition of what, exactly, ‘specific’ might mean.

Most of us have limited time (and energy) to devote to fitness, so it makes sense for us to focus on the things that give the most bang for the training buck. And from that perspective, a few sessions a week of strength training and metabolic conditioning are all you need to get into great shape.

But because Composite works with pro, semi-pro, and serious amateur athletes, we’re also always on the lookout for things (like hyperthermic conditioning in the sauna) that can help juice out additional percentage points of performance gains.

That’s what led us to a series of recent experiments with apnea tables, an idea borrowed from the world of spearfishing and free-diving (a sport of diving to SCUBA depths while simply holding your breath).

Let’s Get Metabolic

To understand why apnea tables work, you first need to know a bit about energy metabolism. When we work out at high levels of intensity, our bodies route around our cells’ mitochondria (which generate energy in a more sustainable, but slower, way) to create energy directly, in the rest of the cell. That process, anaerobic metabolism, is much faster, though it creates an increasing build-up of lactic acid as a by-product, called metabolic acidosis. Eventually, as enough lactic acid builds up, we hit what’s called the lactate threshold: we ‘feel the burn,’ and need to slow down or stop.

But where that threshold is, exactly, varies from person to person. In short, the higher the threshold, the more metabolic acidosis you can tolerate, and the greater your exercise endurance.

As you exercise, your body also creates carbon dioxide, or CO2. And CO2 is a buffer against lactic acid. So the higher the level of CO2 in your blood, the more metabolic acidosis you can tolerate.

We’ve long known that’s one of the ways endurance training works: you increase your tolerance of CO2, which increases your tolerance for metabolic acidosis, which increases your performance and endurance.

Just (Don’t) Breathe

But while you can improve CO2 tolerance indirectly through exercise, it turns out you can also train it directly.

When you’re holding your breath, your body doesn’t actually monitor the amount of oxygen in your blood. Instead, it monitors the amount of CO2. As it climbs, you feel like you need to breathe. But that feeling has a lot of margin of error built in. Most people can only hold their breath for 30-45 seconds, due to CO2 tolerance, but it takes a full 180 seconds, or three minutes, before your oxygen levels really begin to drop.

So free-divers and spearfishers have developed ways to improve CO2 tolerance, in an attempt to hold their breath for longer and longer durations. (With practice, a decent free-diver can go 5-6 minutes on a single hold.)

Their main training tool is called an apnea table, which alternates static periods of breath-hold with decreasing periods of recovery breathing. 

It looks like this:

Round 1 – Hold 1:00 – Breathe 1:30

Round 2 – Hold 1:00 – Breathe 1:15

Round 3 – Hold 1:00 – Breathe 1:00

Round 4 – Hold 1:00 – Breathe 0:45

Round 5 – Hold 1:00 – Breathe 0:30

Round 6 – Hold 1:00 – Breathe 0:15

Here’s a good iPhone app that does a more tailored, dynamic, and easily counted version of the same thing. (It’s what we and our athletes have been using.)

With increasingly brief durations to catch your breath between holds, and less time to flush the carbon dioxide from your blood, your CO2 level will slowly climb over the course of the protocol. Which, in turn, builds your ability to tolerate the increased CO2. (Nota bene: if you’re doing it right, you should likely feel a little light-headed by the end. Sit or lie down while you’re practicing, so that you don’t injure yourself if you happen to pass out. And never, ever try this in water; drowning is tacky.)

From what we’ve seen, most free-divers recommend trying this just once a week, as well as a weekly workout on an oxygen table (where the breathing periods are constant, but the holds increase). While we suspect the latter would be beneficial to endurance, too, we've focused our experiment solely on the CO2 / apnea table, to better isolate its effects.

Great Success!

And, in short, the effects have been pretty impressive. One of our athletes 500m row times had held steady at 1:47 for the past few years. After just six weeks of apnea table practice, however, he pulled a 1:42 – a whopping 5% improvement. And, at least as importantly, a slightly slower row (2:00/500m) now seemed far, far easier in terms of perceived exertion, leaving him much less gassed when one shows up mid-workout. 

We’ve seen similar improvements on running and metabolic conditioning times; the athletes on whom we’ve been testing the apnea tables have seen 3-8% performance bumps across the board. 

At less than 15 minutes of weekly time commitment, it seems more than worth trying out. If you do, let us know how it goes; we're definitely curious to test this further, and will report back with more data once we do.