...ah, yes, back to the ole "sperm and egg" again...
Has all this exercise been a waste of time?
If the hours you've spent at the gym this year haven't delivered the results you wanted, the latest fitness news probably didn't make you feel any better.
At the Australian Health and Medical Research Congress in Sydney, obesity geneticist Claude Bouchard reported the results of a study showing that, for an unhappy few, even regular exercise has little benefit.
"There is astounding variation in the response to exercise," says Bouchard. "The vast majority will benefit in some way, but there will be a minority who will not benefit at all."
Are you one of the unhappy few? And if so, what can you do about it?
Bouchard's comments are based on data collected from the HERITAGE Family Study. As part of the study, 742 people from 213 families were put through a strict 20-week exercise program. Each subject was required to exercise three times per week for an average of 42 minutes.
The team found that exercise improved maximum oxygen consumption, a measure of aerobic fitness, by an average of 17%. Some volunteers improved by over 40%. Others, however, showed no improvement at all. Similar patterns were seen with cardiac output, blood pressure, heart rate and other markers of fitness.
Bouchard reports that the impact of exercise on insulin sensitivity - a marker of risk for diabetes and heart disease - also varied. It improved in 6 out of 10 volunteers. But in the rest, there was no change.
It's worth pointing out that subjects taking part in the study were not given instructions about diet. The fact that insulin sensitivity didn't change might have been because they weren't eating properly.
What's more, the workout routine used in the study wasn't a very effective one.
The program started at 55% of VO2max (the equivalent of a brisk walk) for 30 minutes per session, three times per week. It gradually increased to 75% of VO2max (the equivalent of a steady run) for 50 minutes per session. It was kept at this level for the last six weeks of training.
Subjects taking part in the 20-week trial lost, on average, less than two pounds of fat. That's about 3.5 grams of fat per week. These results are consistent with other trials showing that three days per week of moderate-intensity aerobic exercise has little effect on weight loss in the absence of a controlled diet.
A more frequent or more intense exercise program would have delivered far better results, in terms of fat loss, aerobic fitness and other markers of health.
Researchers from the Cooper Institute in Dallas, for example, have shown that fit but overweight men are less likely to die from cardiovascular disease than lean men who are unfit.
In other words, being fit can counter some of the health risks linked to excess body fat.
Exercise is also a great way to deal with metabolic obesity. Metabolically obese individuals have a normal weight based on traditional criteria. However, their blood sugar and insulin levels are far higher than would be expected based on their weight alone. This increases the risk for type II diabetes and cardiovascular disease.
In one study at the University of Vermont, almost 2 out of 10 women were classed as being metabolically obese. But there was very little difference between the women in terms of weight and body fat.
The metabolically obese women weighed slightly more (132 pounds) than the normal women (129 pounds). Their body fat percentage was also slightly higher (32% vs. 27%).
A workout routine that combines both resistance and aerobic exercise is one of the best ways to beat metabolic obesity.
Both forms of exercise increase the ability of your body to remove sugar from the blood. However, they each work in a slightly different way.
When you train with weights, you gain muscle. And it's this extra muscle that helps to clear the sugar (also called glucose) from your blood.
Aerobic exercise, on the other hand, enhances glucose uptake independently of changes in muscle mass, increasing both the number and function of glucose transporters. These help to transport sugar from the blood into the muscle.
The bottom line
Exercise is not a waste of time, even though there might be times when you feel like it is.
All you can do is get the most out of your own body. There'll be times when you see results very quickly. But there will also be times when you feel like you're stuck on a plateau, and nothing seems to be working. What really counts is where you end up, not how long it takes you to get there.
Exercise is more than a way to change your body. For some, it's an excellent way to improve the way you feel.
Putting in a good workout can give you a real sense of accomplishment. You'll become less tense. As your strength increases, so will your confidence and independence. I believe that exercise is one of the best ways to deal with the frustration and stress life throws at you.
The benefits of exercise can't always be condensed into a list of things you can test for. Remember that the things you can measure don't always count, and what counts can't always be measured.
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