You leave me breathless.

    This article will attempt to illuminate principles of breath
  control that I have derived from many years of experience with the
  sport of distance swimming. For those unfamiliar with movement
  through water, almost everything is at least four times more
  resistive than on land. For example, a 400-meter run is pretty close
  in time to a 100-meter freestyle swim. In the water, the more
  movement is forced, the more the liquid medium resists. For anyone
  who pushes the body out of its comfort zone both on land and in the
  water, knowing how to control breathing is the answer to having a
  good race. While most of what follows is related to swimming, you may
  easily adapt these breath control concepts to any sport. I feel they
  are of particular relevance to triathletes, who--through their
  movement in water, with the mechanical advantage of a bike, and
  finally on land--run the gamut of vigorous exercise.
    Breath control is key to putting the body through prolonged
  vigorous activity and having it not desert you. What constitutes
  "prolonged" is reflective of body physiology and relative to choice
  of endeavor. Sprinters need to control their breathing to prevent
  fading quickly toward the end of relatively brief but intense
  muscular movement. For them, "endurance" can mean one to two minutes,
  and sometimes less. Middle distance and distance people have the
  physiologic ability (along with proper training) to transfer oxygen
  to meet demand for much longer. But in each case breath control is
  what needs to be practiced, trained, and remembered come race time,
  no matter what the sport.

Overview

Rapid vigorous movement, whether sudden or prepared, is expected to bring about the body's compensating mechanisms. These include the most visible and obvious: increased depth and rapidity of breathing. There have been many scientific experiments whereby normal athletes at sea level were given pure oxygen to inhale before and after intense exercise in assumption of either delaying oxygen debt or enhancing recovery. Neither the arterial blood content of oxygen was increased nor the recovery time diminished. Since this proves that the body cannot store or accumulate oxygen to any great extent, the superficial interpretation of this intense breathing response would be that it is simply the body's way of bringing back its supply of usable oxygen. But this is only partially correct.

I submit that rather than simply developing an oxygen deficit as a consequence of intense body movement, the build-up of carbon dioxide (CO2) from increased metabolism is the main cause of the sometimes nearly paralyzing symptoms of breathlessness.

Even a benign situation like being tired (or bored) can cause the body to work at compensation by causing a yawning sequence. This happens more to cause the blow off (forced exhalation) of increased CO2 than it does to cause the inhalation of more oxygen.

One gets drowsy and begins to yawn in a car with several passengers because of the build-up of CO2 in the air rather than any measured decrease in oxygen content. And this manifestation would be even more apparent and occur more quickly in aerobically conditioned athletes because of their ability to extract more oxygen from the ambient air per unit time and leave more CO2 to build-up.

I have also noticed on many occasions that exposure to cold can bring on the yawning reflex; here, due to the increased metabolism (shivering, etc.) necessary to raise body temperature, more CO2 gets produced which is then needed to blow off forcefully.

Unlike plants and trees, which nature has adapted to utilize CO2 in a productive way (the manufacture of oxygen), human physiology has had to come up with metabolic pathways to neutralize or "detoxify" CO2 since its production to excess has deleterious effects.

What happens to the body when it is asked to endure the vigorous activity of swimming fast? Depending upon the duration, intensity, and specific type of movement through water--and, of course, the physical condition and aptitude of the athlete--breathlessness is the endpoint for which to train. This is not an easy thing to ask of an athlete, especially on a constant basis. It is one thing to become short of breath during vigorous land-based exercise; the body usually responds in its natural way of rapid respiration, in-and-out, without much thought given to controlling this process in any way other than the desire to recover as quickly as possible. But do the same in water, and we see a very different picture. No matter how athletic the participant, if one cannot control the breathing part of swimming for as long as the race lasts, the whole technical aspect of the stroke usually breaks down, and movement through water becomes at first less efficient, then downright counterproductive. This negativity is magnified because as one moves faster through the water, the liquid medium holds the swimmer back with resistance that is either squared (under the surface) or cubed (at the surface).

A land-based athlete might analyze this and say, "Why bother?" An experienced swimmer, on the other hand, comes to realize that in the final analysis, it is breath control that dictates speed throughout the race. Miss-pace the race by taking it out too fast, or make the mistake of holding breath too much in the beginning, and all too often the back end of the swim becomes more of a struggle than the swimmer bargained for, all because of the sensation that oxygen is in very short supply.

There are complicated physiological processes that occur in cascade fashion when body movement becomes more demanding than staying in one's "comfort zone." There are dictums and theories about oxygen deficit versus oxygen debt; about recovery oxygen uptake or excess post-exercise oxygen consumption. I will discuss what I feel is the prime motivator to breathe, why we do this, and what happens if we don't.

Some Physiology of the Respiratory Response to Exercise

Metabolically, moving fast in any fashion (for more than just a few seconds) creates biochemical demands that must be "caught up to" and dealt with by the body. The forced deep exhalations automatically succeeding vigorous movement are one way the body tries to bring back its overall pre-activity condition (homeostasis). CO2 is one of the end products of metabolism; it cannot be prevented from forming, but it can be prevented or at least delayed from building up. If there is muscular movement, CO2 is produced. If CO2 is produced in low enough amounts (light to moderate movement) it can be easily carried away by circulating blood through the muscles; there will be no build-up and no sensation to want to breathe vigorously. The typical breathing mechanism will allow for this transported CO2 to be adequately blown off at the lungs. The better the condition of the athlete, the more readily this process takes place.

Eventually, the more CO2 produced, however, the greater the responding respiration becomes. Any time CO2 production rises to a greater extent than can be handled by the rate and depth of breathing, blood will leave the lungs with some residual CO2 in it to be recirculated through the heart and then on to the arterial blood supply and to the body's various tissues and organ systems. If there is more CO2 in the circulating blood, there is less room for oxygen to circulate. One of the typical end-result physical markers I look for in this case is seeing a face with blue lips (cyanosis) at the completion of an anaerobic hard swim.

Since CO2 is being produced throughout the body with vigorous activity, adding more to the immediate tissue environment from the circulating blood only deepens its negative effects. One such effect is actually a rescue mechanism of sorts: there are CO2 sensors in the arterial blood supply which, when stimulated, produce the sensation of "air hunger." This, I feel, is the primary stimulus that causes the breathing center of the brain to want to engage in forced respiration, not what might be construed as a relative lack of oxygen.

With rapid inhalation and exhalation of ambient air, the oxygen exchange is really not that dramatic. As an example of quick inhalation-exhalation oxygen exchange, I submit the scenario of giving CPR to one who needs resuscitation. The ambient air contains 21% oxygen on average; forced air from a rescuer into the victim only contains about 16% oxygen; this shows that the body removes only about 5% of oxygen from quickly-inspired air. In addition, even with well-trained athletes, it takes time for all the respiratory trained mechanisms to kick in--sometimes as much as three minutes, so maximum oxygen consumption and oxygen exchange don't really come into play as quickly as the build-up of CO2.

Physiologic Effects from Exposure to Altered Oxygen in Ambient Air

To put this discussion in proper perspective, I must mention the importance of the amount of available oxygen in the ambient air where and when vigorous movement is initiated. Right from the start, the amount of oxygen in the air and its corresponding pressures do have an effect on athletic performance. Let's look at the powerful influence of available oxygen at different altitudes.

If one trains at sea level where the relative oxygen content of the ambient air is 21%, and the barometric pressure is 760 mmHg (mercury), and the atmospheric oxygen pressure is 160mm Hg, the alveolar oxygen pressure averages about 110 mmHg, and the arterial blood oxygen pressure rises to 96 mmHg. The body gets used to this constant oxygen supply at this pressure while the adaptive enzymes become "trained" to extract what oxygen they have to work with from moment to moment.

Take the altitude up to 3,000 feet and we see the barometric pressure drop to 687 mmHg, the atmospheric oxygen pressure drop to 142 mmHg, the alveolar oxygen pressure drop to 94 mmHg, and the arterial blood oxygen pressure drop to 83 mm Hg. This is an almost 14% drop in blood oxygen content from sea level.

Go to a mile high and the parameters drop to 631 mmHg barometric pressure, 132 mmHg atmospheric oxygen pressure, 85 mmHg alveolar oxygen pressure, and 75 mmHg arterial blood oxygen pressure, a 22% drop in blood oxygen content from sea level. At 8,000 feet high, we observe an almost 35% drop in blood oxygen content from sea level.

You can see from the above numbers that absolute available oxygen is extremely important to the body's ability to extract it for metabolic use; when oxygen is compromised in content, the ability to utilize it is diminished immediately. Here the breathing mechanism and corresponding oxygen metabolism are stressed such that not only is CO2 build-up a certainty but any help from available oxygen to try and offset this will be hard to obtain. A physical manifestation that sometimes presents when respiration is compromised and the athlete is in distress is called "dragon breathing." This is intensely labored respiration and once it begins the body must attend to the recovery from this state at the expense of all other movement.

Holding one's breath during training provides, in my opinion, only one benefit to the swimmer. It helps somewhat in the tolerance of CO2 build-up, something that could prove decisive while streamlining off the walls and into finishes. That said, I am otherwise against breath-holding while swim racing most distances.

Breathing Patterns While Swim Racing

There are two types of distress that the body must be trained to withstand: physiological and psychological. Correct physiologic adaptations are hoped for with appropriate training sets throughout the main racing season. But it is the perceived bodily response and adaptation to the swim training that will prove to be most important in producing fast swims. How you practice is how you race!

Cecil Colwin wrote an informative article on several aspects of breathing when swimming the four racing strokes (American Swimming, 2003, No. 5). I agree with his view that the inhalation aspect of the breathing cycle is noticeably shorter than the exhalation aspect. But I disagree with his assertion that the "used air" should not be forced out with any great effort lest breathlessness ensues more quickly. Exhalation must not be left to simple timing, in-and-out; as one approaches breathlessness during a race, concerted effort should be made to make sure the lungs have purged much of their stale air so more fresh air can be inhaled. Of course the breathing and movement through each stroke cycle should by rhythmic, but this comes with practice and experience. Learning to pace an event and control the breathing cycle is just as important as knowing how to swim the required stroke, maybe even more so. Many a good swimmer has taken a race out too hard and wished he/she hadn't; some are able to "feel" the mistake quickly and rely on their reserve of aerobic and anaerobic conditioning to hopefully salvage the effort, but most usually do irreparable damage physiologically (i.e., breathing-wise) and suffer the consequences.

I've seen this all too often with enthusiastic and energetic age-groupers. They get caught up in the immediate moment of competition and forget the concept of breath control for the whole race. The 100-meter freestyle is a strong example. Usually thought of as short enough to allow breath-holding as in the 50 free, the longer distance proves otherwise. Doubling the distance to 100 in water at full blast requires almost four times the energy (both actual and perceived), since stressful metabolic alterations are occurring in an accelerated rate. The back half of the race is happening in an already "unfriendly" physiologic environment.

I suggest that the only breath-holding event be the 50 freestyle, and even here, some exhalations of CO2 need to occur to assure a breath-holding strong finish. The 100 free should have the swimmer breathe every cycle going into the last 25 meters where and when the athlete's ability to breath-hold during building discomfort will allow the quickest, strongest finish possible. Needless to say, this type of breath control needs to be practiced over and over for all freestyle events over 50 meters so it becomes automatic during the "combat of racing."

I am against "double breathing" in backstroke only because of the negative influence on the smoothness of the stroke cycle; some gravitate to this breathing cycle because the head is out of the water and no coordination of head movement with breathing is absolutely necessary. But the stroke should be trained with the same breath control as freestyle: inhalation on one arm, exhalation on the other arm.

The correct breaststroke rhythm dictates one breath per cycle, and it is here that the inhalation is much shorter than the exhalation if one is to maximize the efficiency of the underwater glide. It is a good chance to blow out mounting CO2.

The butterfly, consuming the most energy per unit time of swimming, requires regular inhalation/exhalation. World records have been achieved by breathing every cycle. This is due just as much to controlling the breath--and keeping the sense of breathlessness at bay longer into the race--as for maintaining the rhythm of the stroke.

Everyone slows down toward the end of a hard race. But with proper breath control, I prefer to have my swimmers slow down less than their competition. Hopefully this will mean a fast swim. Breath control: it keeps you in it to win it.

by Edward H. Nessel, RPh, MS, MPH, PharmD

Coach Ed Nessel is the United States Masters Swimming (USMS) National Resource Librarian and an active member of the Sports Medicine and Coaches Committees. He was selected USMS Coach of the Year in 1998 and to coach at the Olympic Training Center in 2002. He was National Champion in the 100 meter breaststroke for his age bracket in 2003.