Comprehensive information about diving and undersea medicine for the non-medical diver, the non-diving physician and the specialist.
Physical Fitness for Sports Divers
DOWNLOAD this article
The underwater environment causes a diver to be at a tremendous disadvantage due to:
--the difficulty in propulsion through the surrounding water;
--through rapid heat loss to water generally colder than body temperature;
--breathing gas of compressed density;
--the diver uses an altered cardiorespiratory system from a changed environment;
--in order to prevent damage to air-containing spaces in the body, the diver has to accommodate to changes in gas volume and pressure;
--accommodation to the effects of the partial pressure of gases that can cause toxic, narcotic, stimulatory and gas solubility changes to bodily functions.
with full scuba gear have been tested for the amount of work
divers must be in good physical condition to do a sustained swim at 1
or about a 1.15 mph ). One met = 3.5 ml/kg/minute, and since VO2
is 40, a diver swimming 1 knot should be able to reach and sustain 13
on the treadmill. (Some feel that this speed is quite slow and 13
mets is high.)
Swimming at about 60 % of maximum [about 24 ml/kg/min] is slightly below the anaerobic threshold can be sustained for long periods of time since it is not lactate producing. *
The medical evaluation should consider absolute, relative, or temporary disqualifying conditions as well as excessive smoking and substance abuse. Poor muscle tone, lack of conditioning, obesity and other evidence of dietary indiscretion should be a stimulus to advise the diver about fitness. A medical condition that could injure the diver or his buddy diver should disqualify the diver. The buddy-diver system is the universally recognized practice of pairing scuba divers for mutual safety and implies that each of the pair is fully capable of providing effective aid to the other. Limitations in one of the buddy pair upsets this balance of safety.
Obesity represents a hazard to divers because of the common lack of adequate physical condition in obese individuals and because inert gas exchange and its relationship to decompression sickness are modified unfavorably. Total body fat of less the 22% in males, and less than 28% in females is desirable.
Chronic diseases known to be of higher incidence in the elderly present special problems in diving. A significant and important problem in the elderly is the high incidence of cardiovascular disease. Atherosclerosis can affect flow to the brain, heart. kidneys, or skeletal muscles. These disorders may go undetected and high exercise demands induced by swimming with diving gear may result in inadequate oxygen supply and abnormal function of a tissue or organ. Of most importance is the presence of coronary atherosclerosis with coronary artery disease, heart attack or sudden death may occur in unfit divers with coronary disease. Avoidance of serious cardiac problems while diving can be achieved through appropriate screening evaluation (Linaweaver 1977). Exercise testing is a useful means of screening in elderly individuals prior to instituting a diving program.
Sport diving imposes no legal limits on age, but most diver training organizations require candidates to be 15 years old for full certification. Training is provided to younger candidates who receive conditional certification until age 15. Children divers should use dive profiles which minimize risk for decompression sickness to eliminate concern for injury to growing tissues. Equipment must be properly fitted to the young diver. Equipment designed for adults may be unsafe for a child of small body habitus. Individual variation in development, strength, maturity, and intelligence is too wide to set a fixed minimum age for diving. Customarily, 15 years is the usual minimum age for sport diving in the United States.
Women usually have a lower strength capacity than men and a lower aerobic capacity. Women have a higher percentage of body fat. Sedentary women approximate 25% body fat while trained athletic women reach 10-15%. Trained males however average 7-10% body fat. Increased body fat in women provides better insulation from heat loss during diving, and increased buoyancy.
In assessing fitness to dive in women, the same considerations applied to men regarding general health, physical capacity, mental stability, and training should be used.
Divers with neck
and back problems may develop nerve injuries from heavy lifting,
and other diving related activities. Some individuals with severe
of the spine (herniated
may be unable to dive safely due to limitation of motion or severe pain.
Coronary Artery Disease
Coronary artery disease is the most highly prevalent, life-threatening disease in the United States. Its seriousness and prevalence demand special mention in divers. Two million people per year develop this disease, and over 500,000 people per year die from coronary artery disease (American Heart Association 1981). The basic abnormality of coronary disease is partial or complete obstruction of one or more arteries which supply the heart. In the presence of increased work demands, the heart becomes oxygen starved.
There are several consequences of inadequate oxygen supply to the heart during diving. Oxygen deprived heart muscle may develop sudden reduction in pumping function.. Marked shortness of breath and lung congestion will occur with exercise. Although coronary heart disease is usually manifested by chest pain in most afflicted people, the most troublesome person with coronary disease is the person who has no symptoms but who develops marked oxygen deprivation detected only by electrocardiogram. Such people are at greater risk for sudden death since they developed no premonitory symptoms when oxygen deprivation to the heart occurs.
Heart Surgery and Angioplasty
Patients with successful coronary bypass surgery or balloon angioplasty have returned to sport diving. Careful evaluation of the diver’s condition after recovery from surgery and successful demonstration of acceptable exercise capacity will allow some individuals to return to diving.
Detection of heart disease is particularly important in divers beyond the age of 40. Significant coronary disease may exist without symptoms, only to become evident during stress induced by exercise or anxiety. Diving is an environment which can provoke the first symptoms of coronary disease. In many cases the first symptom is sudden death.
Testing for coronary heart disease
be done by exercise stress testing, and should be done in diver
over the age of 40 or those with known or suspected coronary heart
(Bruce and Hornstein 1969).
1. Bruce, RA, et al, 1974. Separation of effects of cardiovascular disease and age on ventricular function with maximum exercise. Am. J. Cardiol. 34:757-763
2. Bruce and Hornstein, 1969. Exercise stress testing in evaluation of patients with ischemic heart disease. Prog. Cardiovasc. Dis. 11:371-391
3. Bruce and McDonough, 1969. Stress testing in screening for cardiovascular disease. Bull. N.Y. Acad. Med., (2) 45: 1288-1305.
4. Dembert and Keith,1986. Evaluating the potential pediatric scuba diver. Am. J. Dis. Children 140: 1135-1141
5. Ellestad and Wan, 1975 Predictive implications of stress testing. Circ 51:363-369.
6. Folkow 1971. Role of Sympathetic Nervous System in Coronary Heart Disease and Physical Fitness. Pp. 68-73. Larson and Malmborg, eds.
7. Heath et al. 1980. A physiologic comparison of young and older endurance athletes. J. Appl. Physiol. 51:634-640.
8. Linaweaver 1977. Physical examination requirements for commercial divers. J. Occup. Med. 19:817-818.
9. Linaweaver 1963. Injuries to the chest caused by pressure changes, compression and decompression. Am. J. Surg. 105:514-521.
10. Master 1950. The two step electrocardiogram: a test for coronary insufficiency. Ann. Int. Med. 32: 842-863.
This page is compiled and maintained by
Ernest Campbell, MD, FACS