Saturday, April 13, 2013

Michael Mosley's "The Truth About Exercise"

This week I watched a fascinating show dealing with recent research on exercise.  “The Truth About Exercise,” which originally aired last year on the BBC, takes host Michael Mosley on a series of visits around the UK to learn about the new ideas and how they may be applicable to his own situation. 

The first stop is Loughborough University, where many UK Olympic hopefuls train, including hurdler Will Sharman.  Mosley asks the athlete whether he enjoys training and Sharman replies “There are some things within my training components that are grueling and I don’t enjoy them at the time.  It’s horrible.”  This corresponds pretty closely to Mosley’s own attitude toward exercise but he challenges Sharman to a race anyway.  During a practice run he pulls a muscle and falls down.  This event introduces the first truth about exercise, “You can easily hurt yourself if you’re not prepared.”

After this ignominious beginning, Mosley meets with Dr. Keith Tolfrey and goes for a jog around an outdoor track.  He wears a face mask that allows the scientist to measure how much oxygen and carbon dioxide he is using and calculate how many calories he is burning at his current pace.  At the rate of 16 calories per minute, Tolfrey tells him, it would take 55 minutes to burn off a cappuccino, a banana, and a blueberry muffin.  The moral? “If you really want to lose weight and keep it off, you have to control what you eat as well.”  On the other hand, even when exercise does not result in weight loss, it confers other benefits, like reducing the amount of fat circulating in the bloodstream.

In order to learn how this works, Mosley travels to his second destination, the University of Glasgow, where Dr. Jason Gill treats him to a huge Scottish breakfast, with fat equivalent to what most people eat in a day.  A comparison of blood samples from before and four hours after breakfast shows that the amount of fat in Mosley’s blood has doubled as a result of the meal.  This fat will end up as fatty deposits on the walls of the blood vessels and in other parts of the body.  The most dangerous scenario is that it may become visceral fat and surround internal organs such as the liver.  From a previous medical test, Mosley knows that he has too much visceral fat.  Also, his father was diabetic.  Dr. Gill then instructs Mosley to go for a long walk.   

The next day Mosley is served the same lavish breakfast but the walking has triggered an enzyme that offsets the effects of the meal.  When his blood is tested again four hours later, the amount of fat is one-third less than it was after the previous day’s breakfast.  The drawback is that the walk took 90 minutes, too much time to fit in on a regular basis.

Mosley’s third stop is the University of Nottingham, where Prof. Jamie Timmons is working to find ways to get more people to exercise.  Previous research by Timmons has shown that people respond to exercise in very different ways.  Based on a four-year study, Timmons and his colleagues determined that out of 1000 people 15% were over-responders to exercise, while 20% were non-responders who did not improve their fitness by exercising.  Eleven genes determine the category for any given individual.  Timmons also measures Mosley’s insulin sensitivity (a predictor of diabetes) and VO2max (an index of overall fitness).  Timmons then has Mosley do a HIT (high intensity training) routine in which he pedals as fast as he can on a stationary bike for 20 seconds, then rests, then repeats the process twice more for a total of one minute of exercise.  Mosley is instructed to repeat this sequence three times per week, three minutes of exercise in all.

At the fourth destination the focus shifts from intense exercise to non-exercise.  Dr. James Levine discusses NEAT (non-exercise activity thermogenesis), which is the miscellany of up-walking-around movement that each person does each day.  Mosley and two other people are equipped with special underwear that measures how active they are and Mosley turns out to be very sedentary.  Over the next 24 hours he makes a conscious effort to be more active, walking, riding a bike, and taking the stairs rather than the elevator.  With very little effort he burns an additional 500 calories compared with the previous day.  According to Levine, new studies show that being sedentary is very destructive to the body.  He says, “There should never be an hour when you’re sitting down.”  Even people who go to the gym may not be doing enough if they are sitting for most of the day.

In order to learn about the influence of the subconscious brain on exercise Mosley makes his fifth journey, to visit Dr. Emma Ross at the University of Brighton.  There he exercises in a low-oxygen chamber and discovers that the brain can be like an overly cautious parent influencing a person to work less hard than he is actually capable of doing.  With additional sessions he finds that he is able to do more than he could at first. 

Mosley has now been following the 12-minutes-per-week HIT routine for one month and he returns to Jamie Timmons to learn whether the program has affected his fitness.  The good news is that his overall insulin sensitivity has improved by 23%, a welcome surprise given his family history of diabetes.  On the other hand, his VO2max, a measure of aerobic fitness, has not improved at all.  As Timmons already knew based on the blood test, Mosley is a non-responder.  Timmons sums up the experience with these words: “The truth about exercise is that it should be tailored to the individual.”  In Mosley’s case this means that he intends to continue the HIT routine, keep trying to increase his NEAT, and remember that “The chair is a killer.”

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