As a firefighter and trainer and in New York City for the past nine-teen years, I've experienced many frigid, New York City winters. I've learned how important it is to protect yourself against the elements, whether battling a tenement fire at 3 AM, when the outside air temperature is hovering at zero degrees, or just jogging over the piles of snow in Central Park, you've got to take measures to protect yourself.
Hypothermia, or the general cooling of the human body, is the technical term for what we refer to as freezing. Mild hypothermia can occur when your core body temperature is between 96° and 99° F, and you'll begin to shiver. Intense shivering (shivering increases body heat producton by four to five times) will set in from about 91° to 95°, and will become less intense at temperatures below 90°. Beware, at the point when shivering begins to diminish, you're headed into severe hypothermia, a possibly life threatening condition.
Severe Hypothermia
- Shivering becomes less intense
- Muscular rigidity sets in
- Unclear thinking, irrational behavior, and possible amnesia can occur
- Move to a warmer atmosphere and seek medical attention immediately
Exercise and Hypothermia
As long as core body temperature is maintained, and sufficient insulative clothing is worn, it is rarely too cold to exercise. By the time inhaled cold air reaches the lungs it's already warmed up to a safe temperature. However, if you suffer from asthma be advised that breathing cold air can trigger an attack.
Luckily the body is able to produce enough heat to maintain core body temperatures under relatively severe cold conditions. Aerobic exercise actually makes this job easier. Three quarters of the energy produced by the body during exercise is converted to heat. Aerobic capacity seems to be unaffected by cold when core body temperatures are maintained. If core (and muscle temperatures) do drop, cardiovascular endurance is similarly reduced. The colder temps in the muscles themselves seem to set off a greater anaerobic metabolism, producing more lactic acid and associated muscle burn. This results in an overall reduction in strength and power that can produced in muscle tissue in severely cold weather.
Wind Chill Index (see chart below)
When headed outdoors for a workout we need to pay attention to the Wind Chill Index instead of just consulting outside air temperatures. Wind increases the rate at which insulating air surrounding the body is whisked away, replaced with colder outside air. Consult a Wind Chill Index (WCI) before excerising outdoors in cold weather. As a general rule, use caution when headed out with WCI of less than minus 20° F. Anything under minus 70° F is considered too dangerous to exercise.
Proper Clothing
Use up to four layers with a ventilation layer next to the skin. One or two layers of insulation under a protective outer shell works best. Be sure to wear gloves and a hat. Large amounts of heat is lost through the top of the head. Keep the neck and throat area covered with a scarf or turtleneck.
Other Options
Cold weather is no reason to skip your workout, but if you feel it's too cold to head outside, bring the workout indoors. Consider a treadmill or other piece of exercise equipment. Circuit training in the gym, or at home using dumbbells, is another great way to get an aerobic workout without having to step foot outside. Click the link to related workout for a great winter circuit workout.
WIND CHILL CHART
Wind
(mph) | Temperature (° F) |
|---|
| 35 | 30 | 25 | 20 | 15 | 10 | 5 | 0 | -5 | -10 | -15 | -20 | -25 |
|---|
|
| 5 | 32 | 27 | 22 | 16 | 11 | 6 | 0 | -5 | -10 | -15 | -21 | -26 | -31 |
|---|
| 10 | 22 | 16 | 10 | 3 | -3 | -9 | -15 | -22 | -27 | -34 | -40 | -46 | -52 |
|---|
| 15 | 16 | 9 | 2 | -5 | -11 | -18 | -25 | -31 | -38 | -45 | -51 | -58 | -65 |
|---|
| 20 | 12 | 4 | -3 | -10 | -17 | -24 | -31 | -39 | -46 | -53 | -60 | -67 | -74 |
|---|
| 25 | 8 | 1 | -7 | -15 | -22 | -29 | -36 | -44 | -51 | -59 | -66 | -74 | -81 |
|---|
| 30 | 6 | -2 | -10 | -18 | -25 | -33 | -41 | -49 | -56 | -64 | -71 | -79 | -86 |
|---|
| 35 | 4 | -4 | -12 | -20 | -27 | -35 | -43 | -52 | -58 | -67 | -74 | -82 | -92 |
|---|
| 40 | 3 | -5 | -13 | -21 | -29 | -37 | -45 | -53 | -60 | -69 | -76 | -84 | -92 |
|---|
| Wind speeds above 40 mph have little additional chilling affect |
Related:
The Firefighter's Workout Book contains over 50 illustrated exercises and routines, including strength, aerobic and stretching programs for every level of fitness.
