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For more than fifty years, athletes in sports requiring endurance have used a training technique called carbohydrate loading. A recent study from South Africa shows that this technique slows sprint performance of cyclists ( Journal of Applied Physiology , January 2006).

Competitive bicycle racers ate a high fat or high-carbohydrate diet for six days followed by a high-carbohydrate diet for one day and completed time trials on their bikes. Then they ate the opposite diet for six days followed by a high carbohydrate diet for one day and repeated their time trial. Diets did not affect their times or power output for 100 kilometers (62 miles), but the high fat diet slowed their sprint performance over one kilometer (0.6 miles.)

Muscles get their energy from sugar and fat stored in muscles and coming into muscles from the bloodstream. The limiting factor in how fast an endurance athlete can exercise is the time it takes to transport oxygen from the blood in the lungs to the muscle. Muscles require far more oxygen to burn fat than to burn sugar for energy. So when a muscle runs out of its stored sugar, called glycogen, it becomes less efficient, hurts, is difficult to co-ordinate and slows you down. Many previous studies show that it doesn’t make any difference what an trained endurance athlete eats on the week before competition because the muscles of trained athletes store the most glycogen when they reduce training for several days, regardless of what they eat. Any difference in the muscle and fat concentration inside muscles becomes unimportant during endurance competition.

This study shows that a high-fat diet before sprint competition hurts performance. A high fat diet causes muscles to burn a higher percentage of fat. Using fat for energy requires more oxygen than carbohydrates do, and how fast you can sprint 0.6 miles on a bicycle is limited by how rapidly you can deliver oxygen to muscles.

Dr. Gabe Mirkin has been a radio talk show host for 25 years and practicing physician for more than 40 years; he is board certified in four specialties, including sports medicine. Read or listen to hundreds of his fitness and health reports at http://www.DrMirkin.com

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Not getting enough exercise? It’s a normal feeling - we all recognize this, and still many things get in our way of actually doing exercise. You witness people crowded into gyms working out, and consider : I have to go to the gym, pay for my member’s fee, then lift some weights. It seems like loads of bother, isn’t there something I can do that’s not going to blow a lot of my precious time - maybe something that’s actually pragmatic?

So you might consider cycling, as bicycling around is a wonderful way to get fit. You can cycle to work or to the shops, so it’s very practical. It’s also very cheap - there’s no gasoline required and the maintenance are negligable. It’s also environmentally friendly. Oh, and it gets you fit too!

But lots of people are reluctant to get a bike because it’s TOO much exercise. As odd as that sounds, it could be because they might live in a very hilly location, be elderly or suffer from particular ailments that make bicycling too much effort for their capabilities. And for some people, it’s not realistic cycling to their work simply because they sweat too much because of the efforts of cycling.

Now it’s time to talk about e-bikes, or electric bikes. Electric bikes give you a rest on the severe hills merely by turning your hand on the grip and letting the electric motor kick in - you don’t need to do any peddling then. Then when you feel up to it, just pedal. So you get your moderate exercise and clean air without over-doing it. Electric bikes are also very cost-effective to operate needing only a daily battery re-charge if you do about 30-40k a day, although most individuals need only a couple of re-charges a week as they are not doing this kind of mileage. For the more adventurous, there are even electric mountain bikes for those who want to get out into the countryside but don’t quite have the calf muscles to scale the slopes.

These days the real cost of getting an e-bike have come right down in price, so you can find yourself saving a lot of cash on fuel, bus fares, gym memberships etc. by purchasing and on a regular basis using an e-bike.