A lot of people in my profession (MMA) have been training with a gas mask or snorkel. I've always chalked up to seeing a buff dude on "Generation Kill" running with a gas mask, so other people started doing it. Or watching a Wanderlei Silva running stairs with a snorkel on youtube and thought if it works for him, it must for me.
What is your take on restricted breathing or Hypoxic training? Is it worth it? Does a breathing ladder produce the same results? Is there a benefit for those who live at a lower altitude and will be performing at a higher altitude (climbing, fighting in a different city, etc)
First, I think your assessment of how this BS started is correct. The images you mentioned plus those of Sean Sherk wearing a gas mask and killing himself on the Airdyne might convince others to try the "technique". One only need look at top athletes in other sports where oxygen utilization is a factor to learn if they have also "discovered" and are using restricted breathing to improve performance. If they aren't, and the use is confined to one particular sport, the tool or technique is likely a fad with no supporting evidence for it.
Somewhere along the way people began to think that harder is better, and if the training means/ intensity really sucks it will produce even greater results. But, to paraphrase a smarter guy, "difficult does not mean beneficial" and this is not restricted to any particular sport or task. Fighting is guaranteed to be hard when you do it, and a certain amount of specific training that matches this level of difficulty is essential but not everything must be done to that level. In other words, getting aggro may train one's attitude and ability to suffer but it doesn't improve technique.
Restricted breathing and hypoxic training are two different things. Restricted breathing taxes the musculature to stimulate structural changes influencing respiration. The stress of hypoxic training stimulates functional, or systemic changes, ideally causing the body to respond by increasing red blood cell genesis.
If the point of the (gas mask and snorkel) training is to cause hypoxia, which has been shown to produce a minor increase in red blood cell production, the limited exposure caused by what most appear to be doing won't produce any results. The standard intermittent hypoxic training protocol used to accelerate erythropoeisis requires normobaric hypoxia in five-minute intervals (with 1:1 recovery breathing normoxic air) for a total of 90 minutes/day, five days/week for three weeks before any results are seen. A gas mask or snorkel does not change the O2 content of the inspired air it simply makes it harder to inhale that air, which suggests the point is not hypoxia but to exercise the breathing musculature to a greater degree than happens under normal training conditions.
Restricted breathing - basically weight training for the breathing muscles - can strengthen the diaphragm and associated breathing musculature, and may (or may not) result in the ability to inhale more air into the lungs. The thesis is that more forceful inhalations allow one to take in a greater total volume of air, and that more forceful exhalations get rid of more CO2 to make room for more O2-rich air to come in. However, getting more air into the lungs doesn't guarantee improved exercise capacity (studies are equivocal) and there are other potential weak links further down the chain.
Resistance/ Strength Training
First, it should be noted that many of the studies relied on to support resistance training for breathing musculature are done on subjects with chronic obstructive pulmonary disease (COPD), and not athletes though several relevant studies have been done.
One study (N=1) demonstrated an 11% improvement in half-mile run time after 28 days of breathing resistance training. While I prefer conclusions reached using more study subjects, this is a compelling anecdote. I note this study because the resistance exercises consisted of 3-5 sets of ten repetitions per workout and a total of 19 sessions, which is very different than a 30-minute run or repeated intervals with gas mask or snorkel, i.e. structured training vs. "fucking myself up."
Another study (N=20) used an eight-week breathing training program and produced what the researchers deemed a significant increase in exercise capacity: from 5 minutes @ 245w on an exercise bike to 6 minutes @ 305w while the control group made no gains. The subjects were "healthy" to begin with, as opposed to being partially-trained or well-trained athletes so they fall into the category of folks for whom "everything works" in the context of training. But such studies do help sell the thesis and the product.
Of greater value - especially for endurance athletes - is respiratory training aimed at increasing the endurance of the breathing musculature instead of its strength. Usually this is done with a Spiro-Tiger device that allows one to progressively increase breathing rate and tidal volume. Normally such hyper-ventilation would cause respiratory alkalosis but the Spiro-Tiger uses different sizes of re-breathing bags to make sure the amount of carbon dioxide in the blood is held constant. I've some experience with this device but I don't currently use it as the benefits were not clear enough to merit the training time required. However, I do know of several world class athletes who use it.
Of the studies I have read, the most significant was done in 2003 (published in '04) with a group (N=20) of "fit" cyclists, meaning they had a mean VO2 Max of 56ml/kg/min, trained more than three hours per week, and rode well enough that neurological improvements would not affect test results. Not fit by our standards but not sedentary. The subjects (N=10) did 20x 45-min sessions of endurance type training of the breathing musculature while one control group (N=4) did 20x 5-min sessions, basically sham training/ placebo, and the remainder (N=6) did nothing. Trainees increased breathing musculature endurance by 12% and improved 4-5% in a bicycle TT consisting of constant work at 80% of VO2 Max for 45 minutes. Interestingly, respiratory muscle strength was not changed by this training so improvements are assuredly along the endurance axis, which may or may not be taxed by the snorkel or gas mask training.
On the other hand, some have hypothesized that this type of training (using the Spiro-Tiger device) also benefits neurological capacities, meaning that one can breathe at near-VO2 Max rate and volume without the physical cost/ stress to skeletal muscles, do so frequently, and this may improve respiratory efficiency during sport performance at that intensity.
Training breathing rate and depth to match physical motions of the sport may also improve performance. This could happen with cycling and running. Swimming imposes inefficient breathing rhythm as well as compressing breathing musculature, though not to the same degree as rowing. The trunk muscles engaged in the rowing motion restrict thoracic expansion so rowers must breathe between strokes, still rhythmically, but generally at higher rates and shallower than a runner or cyclist. Fighters cannot take advantage a rhythmic breathing efficiency.
Filling the lungs with more O2 does not guarantee uptake into the bloodstream. Blood rushing through the vast capillary network of the lungs must offload CO2 and grab O2 on its way through. This is affected by hemoglobin concentrations, and also by the speed of the flow. At very high intensity of effort and high cardiac output (which is higher again in trained athletes than in lesser trained one) blood is flowing through the pulmonary network so fast it can't offload CO2 and enrich itself with as much O2 as is possible at lower heart rates. Blood may leave the lungs only saturated to 90% with O2 when normal O2 saturation should be 97% or higher (at sea level). The more fit you are the lower the O2 concentration in the blood at peak output but there's nothing to be done about this. It's one cost of increased fitness.
O2 off-loading at muscle and utilization there is a potential weak link. This is dependent on the vascular and capillary network, as well as mitochondrial density. The shorter the path from capillary to mitochondria the more efficient the process. To build this network one must include low-intensity aerobic training (to stimulate mitochondrial biogenesis in the slow-twitch fibers) as well as medium- and high-intensity training to produce similar results in intermediate and fast-twitch fibers. Post-effort creatine replenishment is an oxygen-dependent process so increased aerobic capacity in all fibers speeds recovery within the effort. In this context that means during any lull in the fighting, between rounds, etc. So, one must include consistent endurance training in the program and I think this is quite often neglected, and one certainly cannot go long while wearing a gas mask.
Poor posture can result in fatigue during sport performance. The opposite is also true, making this a chicken/egg issue: fatigue results in poor posture, which further reduces performance. In this context, a fighter who has over-developed chest/shoulder muscles that pull, and well-developed lats that push the shoulders forward may experience fatigue induced by respiratory issues: if breathing musculature must fight postural/skeletal musculature to fully inflate the lungs with every breath the net energy expenditure is greater than necessary. If breathing musculature tires first O2 uptake is reduced, starting the fatigue cascade. So training to increase strength and stability of skeletal muscles, and to correct imbalances (postural deficiency) can improve performance by reducing the load against which breathing musculature must work.
This leads to the idea that greater results may be produced by focusing on means other than "increasing the suck factor" by making it harder to breathe. If you are already too strong for the task, if your endurance is already better than required by the task, if you can't possibly improve your jiu-jitsu, takedowns and takedown defense, Muay Thai, boxing, strategy, etc. then restricted breathing training may be a useful training tool but I don't think it offers the best bang for the buck.
Restricted breathing could help one develop (psychological) tolerance to O2 deficit or higher CO2 concentrations but honestly, I think the better, more specific way to train breathing musculature and tolerance is to work against compressive resistance rather than by limiting airflow. Among swimmers it has been shown that enlarged lung capacity is a sport-specific side effect from competitive swimming, possibly due to the compression of the water and resistance to it. It has also been proven that a significant increase in the oxygen cost associated with external chest wall restriction is related to the level of chest wall restriction so being pinned against the mat, even without making an effort to escape will increase the O2 demands of the breathing muscles, while at the same time being harder to inflate the lungs. Training the breathing musculature against compressive resistance by holding sandbag, Kettlebells, barbell, etc. under conditions of high O2 demand should produce better, more specific benefits than restricted breathing. Workouts like "Tail Pipe" where a 40-45 second high-intensity effort on the rowing machine is followed by holding Kettlebells in the Rack position, a sandbag in the wedding carry position, a barbell or slosh pipe overhead, etc. and repeated several times is quite good. You could change the nature of a Breathing Ladder by choosing a light load and holding it throughout the rest periods. All of these types of workouts were developed for our fighters and BJJ competitors when I (a non-fighter) realized how much time they spent breathing against the resistance of their opponent. The problem was quite similar to going hard in the mountains while carrying a pack and I learned long ago that running in shorts and sneakers without a load never prepared me well for that.
To wrap up, you will likely gain greater benefits from working against compressive resistance than airflow restriction - even if it doesn't look as "hardcore" as running in a gas mask. That said you may earn some psychological benefit by working against restricted airflow. Similar psychological benefits may come from fine-tuning the movement/ load of a Breathing Ladder to produce genuine panic breathing as long as you enforce the rules of the rest period duration. Finally, none of this should be construed as having a positive effect on adaptation to higher altitudes, i.e. the gas mask/ snorkel caper won't cause any structural or functional adaptations that will make fighting at a higher elevation any easier, or improve performance there. If that is the objective, then true IHT/ IHE training can help, sleeping in an altitude tent can help, but the greatest benefits will come from living and training at an altitude greater than 2500m (8200') for three weeks or more. TNSTAAFL.