You're racing against another person for 26 miles and as you approach the last quarter-mile, the two of you start to sprint as fast as you can. Your leg muscles start to burn, and they hurt so much that you can't keep up and you lose the race. If you had known about lactic acid tolerance training, you could have won.
You can train yourself to sprint faster at the end of a race by running several 60- to 120-second sprints flat out once or twice a week in practice. When you run without pushing yourself hard, you are able to get all the oxygen that you need, and sugar and fat are broken down into carbon dioxide and water, which you breathe out through your lungs. However, when you break into a sprint, you can't get all the oxygen that you need and large amounts of lactic acid accumulate in your muscles. They make your muscles more acidic, causing them to burn and hurt.
Training to buffer or neutralize the lactic acid can help you to sprint faster at the end of a race.
Once or twice a week, work out by running hard for 60-second intervals followed by jogging slowly for a two-minute recovery periods, and repeat these alternating intervals until your legs start to stiffen up between 12 and 16 repetitions. Other workouts consist of eight to 10 repetitions of running hard for 90-second intervals and jogging four-minute recoveries, or four to six repetitions of running hard for two-minute intervals and and jogging five-minute recoveries.
Q: I don't seem to have much energy anymore. Should I take iron pills? -- D.H., Baltimore
Remember those old ads that claimed a lack of iron caused tiredness? The Federal Trade Commission called the ads illegal because the vast majority of people who are tired will not gain vigor by taking iron.
A diet rich in iron and fat can actually be harmful by causing heart attacks. When you take in extra calories and fat, your liver manufactures large amounts of fat and cholesterol, which eventually end up as the bad LDL cholesterol in your bloodstream. Iron and copper convert LDL cholesterol to oxidized LDL cholesterol which forms plaque in the arteries. A recent report from Finland showed that high iron levels can markedly increase your chances of developing a heart attack.
You can find out if you have high blood-iron levels by asking your doctor to check blood iron, iron binding capacity and ferritin. Since blood-iron levels vary considerably, they are not a good measure of iron. Ferritin is the form of iron that is stored in your liver, spleen, bone marrow and other tissues. High ferritin levels can indicate if you have too much iron, but ferritin can be falsely elevated when you have arthritis or other diseases that cause swelling.
What can you do to reduce your iron intake? The same foods that are rich sources of animal fat are also rich sources of iron: meat, eggs, chicken. Foods that are low in fat are usually low in iron: fruits, vegetables, whole grains and beans.
Dr. Mirkin is a practicing physician in Silver Spring specializing in sports medicine and nutrition.