Muscle lab: Bulk up with the science of bodybuilding - 健身

15:31 18 August 2010 by Jessica Hamzelou


Looking to beef up? As research sheds new light on how our muscles work, it
may be time to scrap old bodybuilding advice. New Scientist brings you top
tips for the budding Mr Universe.

What is the best way to pump iron?

Standard advice for gym bunnies is to lift as much weight as you can in a
training session. But Stuart Phillips and his team at McMaster University in
Hamilton, Ontario, Canada, reckon this might not be the best way to build
muscle. Instead, they suggest that slow and steady wins the race.

In Phillips's study, men in their early 20s lifted weights with their legs
over various periods at 30 and 90 per cent of the maximum weight they could
lift. Phillips analysed biopsies from the leg muscles before and after each
training session.

He found that the production of new muscle proteins was greatest when the men
were lifting the relatively light weights – at 30 per cent of their maximum
– until they were fatigued, and couldn't lift any more.

The idea that you should lift progressively heavier weights to bulk up is
"completely false", says Phillips. Instead, the best way to build muscle is
to lift more manageable weights until you tire out, he says.

Is it easier to rebuild lost muscle than start from scratch?

The phenomenon of "muscle memory" is a handy one for muscle buffs who take
extended breaks between workouts. The idea is that once a person has acquired
a certain level of strength for the first time, they will find it easier to
reach that point again, even if they allow their muscles to waste away in the
meantime.

Kristian Gundersen and his colleagues at the University of Oslo in Norway
reckon the explanation lies in the fact that muscle undergoes permanent
changes during training.

To investigate, Gundersen's team cut the synergist, or "helper", leg muscles
in one leg in mice, thereby increasing the amount of work for the remaining
muscle. After two weeks, the group found that the number of nuclei in the
fibres of the remaining muscle had increased by 37 per cent.

This bulked-up muscle was then left to waste by cutting off its nerve supply.
However, three months later – equivalent to around 10 human years – the
increased number of nuclei remained within the muscle fibres.

Because the nuclei of muscle fibres are key to the production of new muscle
protein, Gundersen thinks that after a bout of training, the potential to
grow muscle sticks with you for life. So no matter how much time has passed
since you were in the peak of muscular fitness, it should be easier to
achieve the second time around.

What about steroids?

Anabolic steroids are thought to work by increasing the number of muscle cell
nuclei. "If those effects are also permanent, the effects of one-time doping
could last forever," says Gundersen. "We may need to reconsider how long the
exclusion period should be for an athlete caught taking steroids."

What's that burning feeling a day or two after a workout?

The ache you feel a couple of days after particularly intensive exercise is
known as "delayed onset muscle soreness". It is thought to be caused by the
lengthening and subsequent damage of muscle fibres during strenuous
stretches. Damaged muscle cells can die off, causing inflammation and pain.
Muscle builders take note: overly arduous workouts could work your muscles
into oblivion.

What's the ideal diet for a bodybuilder?

It is important to get enough protein in your diet, from foods such as red
meat and eggs, as amino acids are essential for making new muscle proteins.
In a 2004 paper, Charles Lambert, then at the University of Arkansas in
Little Rock, and colleagues recommended that protein make up 25 to 30 per
cent of a bodybuilder's diet.

During exercise, most of the energy for muscle work comes from carbohydrates
that have been broken down into glucose and converted to glycogen. Lambert's
team reckoned carbs should make up around 55 to 60 per cent of a
bodybuilder's energy intake.

Before a photo shoot, some male models are known to go to drastic lengths to
look their most buff. A pre-shoot drinking binge dehydrates the skin, so it
is pulled taut over the muscles to accentuate them. A healthier way to look
your best would be to cut fat intake, says Phillips.

But cutting out too much fat could be a mistake. Lambert thinks fat should
make up around 15 to 20 per cent of total energy intake. Reducing fat in the
diet is known to reduce circulating levels of testosterone, which is thought
to boost muscle mass and limb strength.

Journal references: Phillips, PLoS One, DOI: 10.1371/journal.pone.0012033;
Gundersen, Proceedings of the National Academy of Sciences, DOI:
10.1073/pnas.0913935107; Lambert, Journal of the American Geriatrics Society,
DOI: 10.1111/j.1532-5415.2008.01927.x


出處： http://0rz.tw/aih3d 很想上色 但我不會= =

反正每段就看開頭跟結尾就差不多懂意思

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