Monday, November 29, 2010

Air Conditioning Helps Recovery

A study from the University of Montana in Missoula shows that athletes recover from hard workouts faster in room temperatures of 72 F than in 91 F (International Journal of Sports Medicine, August 2010). Nine male participants completed one- hour time trials at 91 degrees F, followed by recovery in rooms at 91 degrees F or 72 degrees F. They were given recovery carbohydrate beverages at zero and two hours. Four hours after the time trial, the athletes in the air conditioned room had much higher muscle glycogen levels (105 vs 88 mmol/kg).

Intense exercise causes the soreness that signals muscle damage that is necessary for muscle growth. Intense exercise also depletes your muscles of glycogen. The faster you replace glycogen, the quicker you recover and the sooner you can exercise intensely again. Athletes who can take the most intense workouts with adequate recoveries improve the most. This study shows that in hot weather, you will replace used-up muscle glycogen faster in air conditioning than at higher temperatures.

Saturday, November 27, 2010

Training in Heat to Improve Performance

A paper from the University of Oregon shows that training in the heat can improve racing performance in the cold (Journal of Applied Physiology, October 2010). Twenty competitive cyclists continued their regular training. In addition, they completed ten 1.5-hour training sessions at 50 percent of their maximum effort (VO2max). However one group rode in a lab heated to 104 degrees, the other group rode in 55 degree lab.

The cyclists who were heat acclimated improved their time-trial performance four to eight percent, while the cold-trained group did not improve.

Training in the heat makes you a better athlete because it cools your body better. Since more than 70 percent of the energy used to drive your muscles is lost as heat, the harder you exercise, the more heat you generate and your body temperature rises. With each increase in body temperature, your body requires more oxygen to turn food to energy. Since lack of oxygen is the limiting factor to how fast you move and how much power your muscles generate, any increase in body temperature slows you down.

Training in the heat increases blood volume so you have more blood available to carry heat from hot muscles to your skin where the heat can be dissipated. sweating begins earlier and is more profuse to cool your skin, and the heart pumps hot blood to the skin faster. All these factors lower body temperature.

Some athletes may decide to heat train by wearing plastic or thermal suits. It could be dangerous because it prevents sweat from evaporating and a person could overheat and pass out or even die. You can help protect yourself from heat stroke by knowing the progressive signs of rising body temperature. See my report on the dangers of swimming in warm water

Monday, November 22, 2010

Ice Delays Recovery from Injuries

More than 30 years ago I coined the term RICE (Rest, Ice, Compression, Elevation) for the acute treatment of athletic injuries. Now a study from the Cleveland Clinic shows that one of these recommendations, applying ice to reduce swelling, actually delays healing by preventing the body from releasing IGF-1 (Insulin-like Growth Factor-1), a hormone that helps heal damaged tissue (Federation of American Societies for Experimental Biology, November 2010).

When germs get into your body, your immunity sends cells and proteins into the infected area to kill the germs. When muscles and other tissues are damaged, your immunity sends the same inflammatory cells to the damaged tissue to promote healing. The response to both infection and tissue damage is the same. Certain cells called macrophages rush to the damaged tissue to release IGF-1 which helps heal muscles.

Healing is delayed by cortisone-type drugs, nonsteroidal anti inflammatory drugs such as ibuprofen, applying cold packs or ice, and anything else that blocks the immune response to injury. Now the treatments for an acute injury include Rest (stop exercising), Compression and Elevation (to reduce swelling), but no ice.

Tuesday, November 16, 2010

Soap Removes Vitamin D

Vitamin D deficiency is very common, even among athletes who spend a lot of time outdoors. Seventy-three percent of athletes tested in a private practice were vitamin D deficient (Clinical Journal of Sport Medicine, September 2010). If you spend a lot of time in the sun and still have low vitamin D, you may have a genetic susceptibility to vitamin D deficiency, or you may just use too much soap (The Lancet, published online June 9, 2010).

Your epidermis (outer layer of skin) makes cholesterol and converts it to 7-dehydrocholesterol. Some 7-dehydrocholesterol remains in the skin, but much of it is secreted in oil to the skin's surface. There exposure to ultraviolet light converts it to previtamin D3 (cholecalciferol). Since both skin oil and vitamin D3 are fat soluble, and not water soluble, a shower does not wash away vitamin D, but using soap does. To preserve vitamin D, use soap where you need it, but don't lather it over your whole body.

Fur and feathers in some animals block UV rays from skin, but their skin oils carry 7-dehydrocholesterol to their hair and feathers where UV light converts it to previtamin D3. They get their vitamin D by licking and grooming their hair or feathers.

Thursday, November 11, 2010

Danger of Swimming in Warm Water

We don't yet know why US swimmer Fran Crippen died in Dubai, but the most likely cause is heatstroke. He disappeared in 86 degree water barely 400 meters from the finish of the six-mile World Cup race.

You are far more likely to suffer heart stroke racing in water temperatures above 80 degrees than you are to suffer heat stroke at any temperature on land. During exercise, more than 70 percent of the energy used to drive your muscles is lost as heat, so your heart has to pump extra blood from your hot muscles to your skin where you sweat. When you exercise on land, sweat evaporates and cools your skin to dissipate the heat. You produce sweat when you swim, but the sweat cannot evaporate to cool your body.

Almost all cases of heat stroke occur when you suddenly increase the intensity of your exercise, like the finishing sprint of a race. Nobody should ever die of heat stroke because your body sends you warning signals as your temperature rises. In 1965, I almost died from heat stroke in an unimportant local running race in Arlington, Virginia. I am still embarrassed by my stupidity because I ignored all the warning signs as my temperature continued to climb. First your muscles are affected, then your circulation and then your brain. As your temperature starts to rise, your muscles feel like a hot poker is pressing against them. It is normal for intense exercise to make your muscles burn, but hard exercise does not cause painful burning that feels like fire. Furthermore, the burning of hard exercise is relieved by slowing down. The muscle burning of impending heat stroke does not go away when you slow down.

As your temperature rises further, the air that you breathe feels like it's coming from a furnace and no matter how rapidly and deeply you try to breathe, you can't take in enough air. When you exercise intensely, you can become very short of breath, but the air you breathe will not burn your lungs. Burning in your lungs, not relieved by slowing down, signals impending heat stroke. When you feel that the air is so hot that it burns your lungs, stop exercising. Your heart cannot pump enough blood from your exercising muscles to your skin so heat is accumulating rapidly and your temperature is rising rapidly. Your temperature is now over 104 and continuing to exercise will raise your body temperature even further and it will start to cook your brain. Your head will start to hurt, you'll hear a ringing in your ears, you may feel dizzy, you may have difficulty seeing and then you will end up unconscious. Your temperature is now over 106 and your brain is being cooked like an egg in a frying pan.

When a person passes out, call for medical help immediately. If it is heatstroke, he should be cooled immediately, but if it is a heart attack, cooling can be fatal. Carry the heatstroke victim into the shade and place him on his back with his head down and feet up so blood can circulate to his brain. Cool him by pouring on any liquids you can find or spray him with a hose. As you cool him, he will then wake up and talk to you and act like nothing has happened. While he's sitting or lying there, his temperature can rise again and he can go into convulsions or pass out again, so he must be watched for some time afterward.

Friday, November 05, 2010

Intervals to Improve Both Endurance and Speed

Cyclists, runners, and almost all other athletes have to move very fast in training to be at their best in competition. However, you can't move very fast over long distances, so athletes use a training technique called intervals in which they move very fast for a short period, move at a very slow pace until they recover their breathe, and then move very fast again and repeat these sprints a few times in a single workout. When you train intensely, you run low on oxygen to cause lactic acid to accumulate in your bloodstream. This makes your muscles more acidic to cause them to burn and you to slow down. We now know that increasing both speed and endurance for competition requires you to train so intensely that you build up lactic acid in practice sessions. This helps the mitochondria, the furnaces in muscles, to burn lactic acid more efficiently for fuel during exercise (AMAA Journal, Fall 2009). In fact, intervals markedly improve endurance for cycling competitions that take many hours and days, because the stronger you are, the less of your maximal effort is needed to get the same pressure on the pedals (Medicine & Science in Sports & Exercise, January 2005).

Duration of Intervals
Athletes in all sports use some variation of long and short intervals. Short intervals take fewer than 30 seconds and because you do not build up significant amounts of lactic acid in that time, often you can do as many as a hundred repeats in a single workout.

Long intervals usually take two to three minutes and are very damaging to your muscles. Because you feel burning in your muscles and become very short of breath for an extended period of time, you can do only a few of these in a single workout. The longer the work/rest interval, the greater the muscle damage, utilization of oxygen and sugar, and using up of muscle glycogen (Journal of Sports Science, August 2005). Athletes in all sports that require endurance usually do both long and short intervals to help them exercise intensely longer.

Short Intervals
You can do a lot more short than long interval workouts in a single workout. Intervals that last more than 30 seconds build up so much lactic acid that you get burning over a long duration that causes significant muscle damage. Short intervals between 10 and 30 seconds can markedly improve all aspects of speed and endurance (European Journal of Applied Physiology, September 2010). Since shorter intervals cause less muscle damage, beginners can start out by doing short intervals as short as six to ten seconds. Thirty-second intervals give you a better training effect and recovery during competition than six-second intervals (American Journal Physiol Regul Integr Comp, December 28, 2006).

Long Intervals
Most athletes do long intervals of two to three minutes. Intervals longer than that cause so much muscle damage that muscles take far longer to recover for the next hard workout. Many athletes do intervals lasting much longer than three minutes, but these very long intervals cause so much muscle damage that they do not do them more often than every few weeks.

Duration of Rest Between Intervals
The shorter you rest between intense intervals, the longer it takes to recover (Medicine & Science in Sports & Exercise, August 2005). Conditioned athletes doing four-minute intervals usually can recover for their next interval within two minutes (Medicine & Science in Sports & Exercise, September 2005).

Therefore most athletes slow down long enough to
• recover their breath,
• slow down their breathing, and
• relieve the burn in their muscles.

Then they do their next long interval. Most athletes start their next interval before complete recovery of heart rate and breathing rate. They should not do the next interval when muscle burning is still present. They usually terminate a workout when muscle burning or soreness persists.

Runners and cyclists often use heart rate monitors or a clock to determine when their heart rate has dropped low enough to start their next interval. Weight lifters usually wait for their bodies to "feel" recovered. Athletes learn their ideal interval rest duration during a workout through trial and error. You can use whatever yardstick for recovery from each interval you like, but if it takes you longer than two days to recover from an interval workout, you are probably exercising too intensely, doing too many repetitions, or not taking a long enough interval rest.

How Often to Do Intervals
Every time you do intense interval training, you cause a tremendous amount of damage to your muscles. Obviously it takes time to heal. If you try to do an interval workout again before your muscles have recovered, you put yourself at high risk for injuries and also impair your training because you can't train fast on damaged muscles. As a general rule, the only sport in which athletes try interval training more often than three times a week is swimming. Most athletes in most sports cannot recover faster than 48 hours from intense interval workouts. In sports such as running or cycling, competitive athletes do not improve by increasing their volume of low intensity exercise without also using intense training. Furthermore with interval training, many athletes have to decrease the volume of their slow recovery workouts done on the days after interval workouts.

Avoiding Over-training
Going out and exercising slowly over long distances will not give you much endurance unless you also exercise intensely once or twice a week at much shorter distances. A person can run a marathon or ride a bicycle century much faster by training fast two or more times a week. The most common mistake made by endurance athletes is to exercise so much that they can't maintain their speed training on their hard interval days. This is often seen in runners or cyclists who perform so many miles per week that their fast workouts end up much slower than they should be.

Scientists used to think that the primary cause of muscle fatigue during endurance exercise was running out of glycogen, the sugar that is stored in muscles. They now know that cumulative fatigue and soreness that does not go away are caused primarily by damage to the muscle fibers. The best way to protect muscle fibers is to strengthen them by exercising against increasing resistance by running, cycling, skiing or skating faster once or twice a week. However, every time that you exercise more intensely, your muscle fibers are damaged, so you have to allow time for recovery by exercising slowly the rest of the time.

How to Include Interval Workouts in Your Exercise Program
If you want to gain the endurance to walk, run, swim, cycle, skate, ski or dance for an extended time, pick two days, say Tuesday and Thursday, for speed and the rest of the time for less intense recovery workouts or days off.

On Tuesday, warm up and then start an interval workout by doing five-second intense intervals followed by a marked slowing of your breathing and complete disappearance of muscle burning. Only then should you start your next short interval. When your muscles start to stiffen or the muscle burning takes a long time to go away, you must stop your workout. Otherwise you may take weeks to recover from that workout. After many months, you will become stronger and you can try to work up to the point where you can do lots of 30 second intervals in a single workout.

On Thursdays, start out the same way as your Tuesdays but then try to work up to the point where you can do repeat bouts of sustained exercise for two minutes. Rest until you recover your breath and the muscle burning disappears, and then repeat these fast two-minute intervals three to eight times. Of course, these long intervals will be significantly slower than your short intervals.

WARNINGS: INTENSE WORKOUTS CAN KILL PEOPLE WITH BLOCKED ARTERIES. Before you start a new exercise program or increase the intensity of your program, check with your doctor.

Always stop exercising, particularly in interval workouts, as soon as you feel pain in one area that worsens with continued activity. Always stop a workout if you don't feel good. Never take an interval workout, or do any intense exercise, when your muscles are sore from a previous workout. On recovery days, exercise at reduced intensity.