23 December 2007

Exercising Efficiently, the Intensity Debate:

There has been a debate raging for some time regarding how we should exercise. One side argues for anaerobic based training and the other for aerobic based training. The essential question being debated is whether or not we can exercise more efficiently. However, as we will find, this is a rather vague question as there is no set criteria to deem what efficiency is in this instance.

The older school of thought supported the aerobics craze. Everyone knows the old exercise videos from the 80’s with girls in coloured swimsuits jumping up and down for hours on end. If you don't, consider yourself lucky. Aerobics systems they argued burn more fat for fuel than anaerobic systems, and thus are better for fat loss. But the anaerobic fans retort that post exercise recovery from anaerobic exercise has the greatest affect on fat burning. In turn the Aerobics group advocate that aerobic exercise or “cardio” as its often called is better for the heart as it improves cardiovascular health and the circulatory system.

The more modern trend has been a move away from aerobics and into the weight room where anaerobic exercise has come to dominate. The anaerobic supporters argue that extensive aerobic exercise causes injury; however the aerobic supporters argue the same of intensive anaerobic exercise, so it’s a draw on that front. Anaerobic exercise also has the added benefit of stimulating more muscle growth and improving bone density. Another thing that is sometimes too lightly overlooked is the increase in hormones that anaerobic exercise causes.

The debate between the two groups has largely revolved around fat loss, which is really only one small category of total health and wellbeing. Regarding fat loss the anaerobic supporters often argue that one only has to compare the physique of a sprinter to a marathon runner to see the benefits of added muscle and hormonal changes as a result which typically mean the sprinter also has lower body fat levels! Yet as far as I am aware type 1 muscle fibres (which are best at endurance work) tend to burn fat much more effectively than type 2 muscle fibres (which are best at brief intense work).

Genetic experiments on mice have certainly had interesting results and can help to shed light on the difference between the muscle types (and by association types of exercising). There are many sites which cite these genetic tests on mice, but this one: http://www.sciencenewsmagazine.org/articles/20041030/bob9.asp seems to be quite in depth and as such I shall use it as a reference.

Mice who have had their genes altered so as to give them more fast twitch muscles (dubbed “Schwarzenegger mice”) have a much easier time growing muscle and staying strong. However, the shocking part is that these mice can gain strength without exercise simply by being injected with a certain gene! “Young mice injected with the gene grew stronger and more muscular, even without exercise.

On the other hand: “Another set of experiments, by scientists at the Salk Institute in San Diego, produced mouse muscles that just keep going without fatiguing...Ronald Evans and his colleagues had started out with the intention of engineering mice that stay trim. To do this, the researchers inserted genes that code for a fat-burning protein called PPAR-delta…The mice that resulted stayed slender, even when fed a high-fat diet, but also developed an unusually large number of slow-twitch muscle fibers, the type the body relies on during extended exertion. ‘This change produced the 'marathon mouse,' able to run twice the distance of its normal littermate,’ vans says.

Personally I would argue that it seems that the slow twitch mice win when it comes to maintaining a low body fat, while the fast twitch mice win when it comes to strength and muscle mass. So ultimately the question then becomes what are we trying to accomplish more efficiently through exercising? Most people wish simply for fat loss, and in the case of mice it would seem that slow twitch endurance based work would serve one better, however again we can compare the images of a sprinter to a marathon runner and wonder.

The debate rages on and it seems that each side has ample ammunition, we will find no answers on the battle field. In particular the recent increase in popularity of
“High Intensity Interval Training (HIIT):” has thrown another spanner in the works, but this itself deserves its own article and so I shall write one in the future.

Common sense would seem to suggest that while one method of exercising may be slightly superior to another (of course this also depends largely on what your goals are!), it is ultimately best to do what you are comfortable with. Most people forget that we are only human. For instance, while in theory we may gain best results from doing something everyday, maybe in reality the most we can consistently do it so that it is sustained is once every second day. What this ultimately means is if you like marathon running then do it, on the other hand if you like sprinting then do that!

Of course I would ask that we look further than just the aesthetics here and look at our total wellbeing. From a point of overall health it would seem self-evident that doing both aerobic and anaerobic activity will be best for our health. This would indeed allow for a more moderate exercise routine which would probably yield better results long term anyway.

It is also interesting to think that we should not all be doing the same thing. When one thinks about it, it makes perfect sense, but often we simply do not think about it and follow the herd instinct of doing what others are doing. The simple truth is that while we are genetically not that dissimilar from one another (say in comparison to a soy bean) we do vary and thus we as a society should be more open to the idea that different people require different things based on their differing genetics. Sprinting might help make your friend lose weight given his biological chemistry, but maybe you’d have more luck with aerobic work. In the future we will no doubt have gene testing which will help us to be able to work with our strengths, but until then all I can say is experiment, enjoy the process, and figure out yourself what you enjoy doing and what works for you.

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