Tuesday, July 21, 2009

History becomes legend

"And some things that should not have been forgotten were lost. History became legend. Legend became myth" Galadriel, Lord of the Rings.

This quote from "Lord of the Rings" reminds me of some of the trends and theories that float around the health and fitness world. It seems that some take a little pinch of science and morph it into theories which sound good, but ultimately don't achieve anything.

Take, for example, the idea of a "fat burning" zone. I've heard this a lot around the bodybuilding traps these days - "I'm only walking, to ensure that I stay in my fat burning zone and that I don't burn muscle by exercising intensely. "

Let me say for a start that the statement as is doesn't make sense from this little exercise physiologist's point of view:
a) Yes, there is a heart rate zone where the body uses fat as substrate for fuel more (eg 50-75% of Max HR) but the truth is that the body runs on carbohydrates, either by the process of gluconeogenesis or glycolysis. Fat is converted into carbohydrate for use as fuel. At higher heart rates, the body relies more on carbohydrate (which comes from stored sources, ie glycogen). Unless you're in a super deficit and eating a very low protein diet, it's highly unlikely that doing high intensity work will cause any muscle loss whatsoever. The joke is that when you are doing very intense strength training your heart rate will peak way above the "golden fat burning zone" that some of these bodybuilder types will promote! What happens then, burning muscle? Hardly - rather setting the body up to gain lean mass if nutrition principles are sound.

b) One secret to becoming a lean mean fat burning machine is to actually concentrate on getting fitter. Yep, get fitter and you will train your body to preferentially use fat as substrate during exercise and rest. This means instead of having to walk, you can run for half the time, half the stress and the same caloric expenditure occurs! At the end of the day, fat loss is related to caloric expenditure, "afterburn", and process of recovery from strength training bouts. On this note, I get told that "if I run, I'll release too much cortisol and I'll be catabolic". Whilst it is true that training switches on catabolic hormones, a fit runner will release far less cortisol than an inefficient one - and addressing post workout nutrition/correct supplementation will go a long way in flipping the switch towards a more anabolic environment.

c) I have to add that overdoing the cardio is no good for athletes who are focused on strength training. When I hear of competitors doing two hours of cardio a day to get lean, big question marks can then start to be raised about retaining muscle etc however 30 minute bouts of intense cardio interspersed with the lighter stuff shouldn't hurt anyone's cause, particularly if nutrition is sound.


Training today: Back and triceps with Shelley. After a slowish start, we both got into it and caned it!
Cardio: total slug fest today (ie nothing). But hey, I stayed in my fat burning zone...heh heh


Frankie said...

Nothing like a good Ex Phys rant. I can't WAIT to get back to uni next week! he he

Andrea said...

I love your scientific mind liz!

ss2306 said...

Was this a 'WANKER' alert? I'm hearin' ya.

Kek said...

Oh noes! I didn't stay in my fat-burning zone this morning! How will I ever get lean? ;o)

That's almost my favourite myth. Wish I had a dollar for every time that's been trotted out....