Shape Up: Marathons can be step in wrong direction for fat
Published 18/10/2010 | 05:00
The Adidas Marathon is almost upon us, which means that many of its participants at this stage are tapering down their training to prepare for the task that awaits.
I admire the discipline and preparation of these athletes and the many sacrifices they have undertaken to enable them to complete the 26.2 miles around Dublin's fair city. The achievement of this goal is not just about its completion but the journey, the lessons learnt, and the person they have become in attempting it.
For many, marathon day represents the culmination of five months' planning, discipline, dedication, persistence and hard work.
So why, then, are runners' physiques sometimes at odds with all this hard work? Elite runners will resemble the gaunt image of John Treacy in his hey-day, whilst others will be overweight and carrying excess timber. But why is long-distance running not the most-efficient method for fat loss?
Marathon runners are renowned for clocking up a colossal number of miles during their preparation. The longer you run, the greater the release of stress hormone cortisol. Cortisol is known as the grinch of body-building as it leads to muscle wastage.
This leads to a more sinewy and emaciated look on experienced long-distance runners as the body starts to lose muscle in response to long aerobic efforts.
As muscle burns calories, and a reduction in muscle reduces calories burned, this would help explain the look of some beginner runners who appear to be carrying excess timber, even after months of training.
Cortisol is like a truck load of timber getting delivered to your house. Some people will burn it and lose muscle whilst others will store it and build an extension out the back with it and gain fat.
Robert Zapolsky, in his book 'Why Zebra's Don't Get Ulcers', explains that we are under constant stress.
When a zebra gets chased by a lion, the stress is temporary and he will either live to tell the tale or he will be the lion's dinner. If the zebra lives, his stress levels will soon return to normal.
In training, however, our stress lasts much longer and in marathon training, it can last for two hours. For the first 20 minutes of exercise our body responds by producing testosterone and we maintain this for roughly 40 minutes. Testosterone helps us build muscle, which burns calories. After that time we produce more cortisol.
There are more efficient methods to improve your health in less time and burn fat while you're doing it. Last year the American College of Sport's Medicine's 'Exercise and Sport Sciences Review' published a paper saying that intense aerobic interval training provided many benefits for the heart, compared to low or moderate intensity exercise.
It increases maximal oxygen uptake, heart muscle contractile function, slows down ageing, reduces cardiac dysfunction in metabolic syndrome and overall it improves quality and length of life by avoiding fatal heart attacks.
It also increases your basal metabolic rate, which is the minimum calorific requirement needed to sustain life in a resting individual, and it increases excess post-exercise oxygen consumption (EPOC).
EPOC is the oxygen uptake, above resting values, used to restore the body to pre-exercise condition. EPOC is accompanied by elevated fuel consumption.
Diana Schwarzbein, an endocrinologist from the Endocrinology Institute of Santa Barbara in California, says that cardiovascular aerobic training increases cortisol secretion, which accelerates ageing and leads to more stress, impairs the immune system and it can lead to insulin resistance.
Our goal in training for fat loss is to improve insulin sensitivity so that our muscles can utilise the foods we eat better and store less as fat.
In an exercise and time-poor society, it is encouraging that research studies consistently state that high intensity aerobic interval training, performed three days a week for six weeks, is a powerful method of increasing our muscles' capacity to oxidise fat.
For many of those training for the marathon, the goal is purely to run the race, to complete the course in whatever time, so fat loss mightn't be high up on their agenda.
Whatever the objective, the key is to train hard and train frequently in order to achieve your goal.