Hyperventilation and hypoxic training
What's the difference, and are they both dangerous?
By Judith Sperling, Assistant Director - Risk Management, Training & Development, UCLA Recreation
Hyperventilation, breath-holding, shallow water blackout and hypoxic training are terms that aquatic professionals frequently encounter and that can be confusing, especially when trying to determine what safety policies to implement at an aquatic facility. Additionally, it is important for aquatic professionals to provide their lifeguards with sufficient accurate information regarding these topics so they are fully equipped to prevent dangerous activities and appropriately react to emergencies.
Hyperventilation is a series of deep breaths followed by forced exhalation prior to breath-holding. This is done in an attempt to remain underwater for a longer period of time. This works because it decreases the level of CO2 in the blood. CO2 is responsible for triggering the need to breathe. With less CO2 a swimmer will not feel a need to take a breath as quickly and can remain under water longer. This, however, does not mean that the swimmer does not need oxygen. Oxygen levels are being depleted. In fact, oxygen levels can be depleted more quickly if the swimmer is moving or swimming rather than remaining stationary. If oxygen levels in the blood drop sufficiently before CO2 levels trigger the need to breathe, the swimmer will become unconscious. This is also commonly referred to as shallow water blackout. Obviously, an unconscious swimmer will breathe water into their lungs and will die if not rescued and resuscitated.
For this reason, a number of agencies have standards or policies prohibiting hyperventilation or breath-holding. The American Red Cross refers to hyperventilation in its Swimming and Water Safety text as "potentially dangerous" and "risky" and in its Safety Training for Swim Coaches as "a dangerous practice that may result in drowning." The American Red Cross's Lifeguarding text also refers to how hyperventilation can result in a passive drowning victim and that patrons should be directed not to engage in prolonged breath-holding (greater than 30 seconds). The medical advisory committee of the YMCA of the USA states that YMCAs should prohibit extended underwater breath-holding. The Department of Morale, Welfare and Recreation (MWR) of the U.S. Navy policy states, "This practice of hyperventilating and extended breath holding is prohibited at MWR aquatic facilities. Signs will be posted prohibiting breath-holding and hyperventilation." The Canadian Forces Personnel Support Agency (CFPSA), while recognizing the need to train certain military personnel by engaging in high-risk aquatic activities such as extended breath-holding (anoxia training), also states "...they must do so under the direct supervision of a 'buddy' (the buddy may not be an on-duty lifeguard). In addition, anyone wishing to do anoxia training must inform the lifeguard prior to commencing the session."
It is clear that hyperventilation and prolonged breath-holding are dangerous and aquatic professionals need to develop prevention and education strategies. Tom Griffiths, Director of Aquatics and Safety Officer for Athletics at Pennsylvania State University advocates the prevention of competitive and repetitive breath-holding. All pools at Penn State post a sign stating, "No prolonged underwater swimming or breath holding" and "Competitive and repetitive breath holding can be deadly." In Dr. Griffith's May 2004 article "Playing it Safe" for Aquatics International, Tom reminds us that "those most likely to succumb to 'shallow water black out' are the most skilled people in the pool." Lifeguards tend not to pay as close attention to the highly skilled which could mean a missed rescue. To prepare lifeguards for this scenario, they need education and training. The American Red Cross and the YMCA both provide this information in their lifeguard training texts and the Red Cross has an in-service training outline which includes prolonged breath-holding information in its Lifeguard Management CD-ROM. Despite the fact that these agencies have included information in their training manuals, most facilities do not have policies addressing this issue. Dr. Griffiths conducted a six month survey of nearly 300 aquatic professionals and found a significant number did not have rules or signs banning prolonged underwater swimming and breath-holding. To emphasize that these risks are genuine, 11% of the sample experienced 'breath-holding' rescues requiring resuscitation, with one third of those being fatal.
Aquatic facility managers should consider having policies and/or signs to mitigate the risks of hyperventilation and prolonged breath-holding. The City of Los Angeles' City Wide Aquatics does have such a policy. Aquatics Director Joe Batarse provides education and training for lifeguards and managers so they are familiar with the policy and can prevent this practice. Aquatic facility managers should also consider the different types of programs that they offer when training lifeguards regarding prolonged breath-holding. Programs such as synchronized swimming, underwater hockey and snorkeling (both stand alone and incorporated as part of a scuba program) may require additional information for lifeguards to use to assess participants in these activities and to recognize when someone needs assistance or rescue.
While not common in the U.S., it is important to acknowledge an 'extreme sport' generally known as static apnea. Typically, when we think of hyperventilation or competitive breath-holding, we picture the swimmer who desires to swim increasingly longer distances underwater. Static apnea is a competitive sport particularly popular in Europe with enthusiasts who attempt to increase time underwater in a static or motionless position. The sport is practiced in pools, usually sitting on the bottom, and typically includes the use of weights. There are two world associations, AIDA and CMAS. These associations also govern other competitive freediving sports that include underwater distance swimming with and without fins. Astonishing times have been achieved in the sport. The 2006 static apnea world record for women is 7 minutes, 30 seconds and for men, 9 minutes, 4 seconds. Typically, aquatic professionals encounter the sport when an enthusiast is visiting their pool and wants to continue training. The recently well publicized television stunt of David Blaine's "Drowned Alive" could further popularize "breath-holding sport" and bring more enthusiasts wishing to "practice" in aquatic facilities. It is important for aquatic facility managers to recognize the implications of allowing such training in their pool. Consider the fact that we train our lifeguards to regard anyone who is submerged or face down and motionless for 30 seconds as a passive drowning victim, and we require them to check on the victim's condition immediately. It is difficult if not impossible for our lifeguards to know when a static apneist is in trouble since he/she will be underwater for much longer than 30 seconds. Certainly this should never be allowed during a recreational swim period as the lifeguard attention required to supervise this activity would dangerously decrease attention needed for other persons in the pool.
The development of hypoxic training is credited to the legendary swimming coach Dr. James Counsilman of Indiana University. Hypoxic training is 'low oxygen' training and involves the reduction or elimination of breathing while training. In swimming, this typically involves breathing every 5, 7 or 9 strokes or limited underwater swimming. It was originally thought that reducing levels of oxygen would result in physiological adaptations similar to high altitude training. In addition, it is also believed that reducing the number of breaths would increase the swimmer's speed as breathing tends to increase drag. Subsequent research has proven that sea-level hypoxic training does not produce any physiological adaptations. Hypoxic training, however, remains popular as it familiarizes swimmers with the discomfort and stress of low oxygen and can discipline swimmers to keep strong techniques during the stress of a race.
Some swimmers and coaches have taken hypoxic training to the extreme by combining it with hyperventilation, with tragic results. The scenario is almost always either "lung buster 25 repeats" or underwater swims to maximum distances. For this reason, the CFPSA has defined hypoxic training by limiting it to "exercise at levels of reduced oxygen" rather than no oxygen from extended breath-holding. USA Swimming recommends that "...hypoxic training should be carried out only under close supervision." The American Red Cross states, "Hypoxic training (breathing on a restricted schedule) may be used safely in a training program of experienced swimmers in good physical condition with proper supervision and instruction. The number of repeats of practice sets of hypoxic training should be limited. Adequate time for recovery will vary from swimmer to swimmer. Hypoxic training should be limited to older and more experienced swimmers....To prevent hyperventilation, have swimmers take only one, or at the most, two deep breaths before beginning hypoxic training." Lung capacity diminishes with age, so Kevin Milak, technical editor for Swimming Technique magazine, recommends that "Masters swimmers using hypoxic training should be watched very carefully." Although there are differing opinions regarding the value of hypoxic training, there is large support for doing so only under close supervision.
In the development of a policy to address these issues, be sure to define terms that you use when prohibiting or restricting activity, such as the CFPSA did in their 'Aquatic & Water Safety Policy' when they defined hypoxic training. One city researched had a very strong policy prohibiting 'free diving and hypoxic training,' which was confusing because it was known that they had a local swim club that used hypoxic training. However, they defined hypoxic training as involving "an individual holding their breath underwater as long as possible." While this definition does not accurately reflect the current prevailing definition of hypoxic training, their definition did help to clarify exactly what this city was trying to prohibit.
In my opinion, hyperventilation should always be prohibited. Strategies to minimize or eliminate the risks of hyperventilation, prolonged or extended breath-holding and hypoxic training are:
- signs prohibiting or restricting the activity
- in-service training and education for lifeguards and coaches on what rules should be enforced, what to look for, how to react, and emergency action plans
- policies that prohibit or restrict the activity
- policies that require any one or more of the following: supervision, buddy system, notification of lifeguard, permission of management, permission of parents, signing waivers
Aquatic professionals may choose any one or more of these strategies to address their particular needs. Assessment of aquatic programming, lifeguard training, audiences and resources must take place in order to determine which strategies will most effectively address the dangers associated with hyperventilation, prolonged breath-holding, and hypoxic training at a particular facility.
- ABC News, David Blaine: 'Drowned' Alive http://abcnews.go.com/GMA/story?id=1913098&page=1
- American Red Cross, Lifeguarding, 2007.
- American Red Cross, Safety Training for Swim Coaches, 1996.
- American Red Cross, Swimming and Water Safety, 2004.
- Aquatics International, Playing it Safe, Tom Griffiths, May 2004.
- Association Internationale Pour Le Developpment De L'Apnee, www.aida-international.org
- Athletic Business, Game On - Don't Hold Your Breath, Paul Steinbach, Jan 2007.
- Canadian Forces Personnel Support Agency, Updated Direction on Hypoxic (Anoxia) Training, Nov 2003.
- Confederation Mondiale des Activites Subaquatiques, www.cmas.org
- Swimming Technique, Lowdown on Hypoxic Training, Kevin Milak, Jul-Sep 2003.
- Tom Griffiths, Aquatic Safety Research Group, LLC., unpublished research.
- USA Swimming, Safety/Loss Control Manual, Nov 2005.
- USA Swimming, Speedo Tip of the Week, Freestyle Breathing Mechanics, Terry Laughlin, Nov 15, 2004.
- U.S. Navy, BUPERINST 1710.11C, Chapter 15 Aquatic Programs and Facilies, 1523. Hyperventilation and Breath-Holding.
- YMCA, Statement of the YMCA of the USA Medical Advisory Committee, Jan 2004.