When Your Wetsuit Turns on You

Wearing a wet suit in the wrong conditions can lead to anxiety and panic, according to the results of a study by Drs. K. F. Koltyn and Wm. P. Morgan at the Department of Kinesiology at the University of Wisconsin-Madison, which was funded by the University of Wisconsin Sea Grant Institute. This is a synopsis of their study.

Panic is the primary cause of death in scuba diving, especially when it precedes an uncontrolled ascent that result in death. If, for example, a diver is too warm or too cold, it is possible that anxiety might occur and provoke a panic response.

On land, aerobic exercise reduces anxiety. But does that work in diving?

Preliminary research on the interaction of exercise, water temperature, and wet suits reveals different anxiety responses for different temperatures. In a study six years ago by K. F. Koltyn, C. L Shake, and Wm. P. Morgan, ten certified divers completed 30 minutes of finning in warm (29°C) and cold (18°C) water without a wet suit.

As might be expected, in the cold water anxiety decreased significantly when divers wore a wet suit and increased significantly when they did not.

However, in the warm water, anxiety increased significantly when divers wore a wet suit. There was no significant change when they did not.

Because of these results, Drs. Koltyn and Morgan examined how a wet suit influenced temperature and anxiety during underwater swimming. They wanted to determine the effect of wearing a wet suit on air consumption, respiration rate, breathing distress, heart rate, perception of effort, and how these variables affected anxiety.

Thirteen male certified divers (mean age 25) were tested in an indoor pool with water at 24°C (75.2°F). On separate days, the divers wore a bathing suit, and the second a quarter-inch neoprene wet suit, without hood or gloves. Core temperature was measured before, during, and after underwater exercise with a rectal thermometer attached to a 2 m extension attached to a digital display thermometer. Heart rate, respiration rate, and compressed air use were assessed throughout the study.

Once submerged, the divers became neutrally buoyant, then rested for 10 minutes at 1.5 meters. They answered test questions (the Body Awareness Scale and the State-Trait Anxiety Inventory) using a clipboard and grease pencil. This was followed by a 20-minute moderately paced kicking swim. The divers made subjective ratings of perceived exertion (arms, legs, and overall) via an underwater communication system during the swim. Rate of breathing was recorded. They rested again, and completed questions. After they left the pool, thermal and comfort ratings were assessed and the test questions repeated.

Results

As expected, during swimming the divers' heart rate, respiration rate and air consumption increased significantly in both the bathing-suit and wetsuit conditions. In the wet suits, however, heart rate and air consumption were significantly higher.

Wearing a quarter-inch wet suit resulted in a significant increase in core temperature and led the divers to feel warm. In comparison, core temperature remained unchanged after underwater exercise while wearing a nylon bathing suit; these divers reported a "neutral" feeling, neither warm nor cold.

When clad in a wet suit, the divers registered a significant increase in anxiety immediately after swimming, while in bathing suits they did not. Fifteen minutes after swimming, the anxiety was significantly lower when clad in a bathing suit rather than in a wetsuit.

Perceived exertion increased significantly after swimming in the wet suit, while in a bathing suit the rise was insignificant. Wearing the wet suit was associated with increases in heart rate, respiration rate, and air consumption, but these were independent of anxiety responses. In other words, divers can be aware of their breathing without experiencing anxiety responses.

These results demonstrate that

• the anxiety-relieving effect of underwater exercise occurs in the absence of an increase in core temperature.
• an increase in core temperature is actually associated with elevated anxiety.

Because increased anxiety can lead to panic and panic can cause uncontrolled ascents, unnecessarily wearing a wet suit in tropical water increases diving risk. And you surely burn more air.

Ben Davison