Ian Short

I’ve just read The first 20 minutes by Gretchen Reynolds. It’s a tour of the latest research into the science of exercise, which has advanced significantly over the past ten to twenty years. The author is a journalist, and it’s written in a popular style. There is no reference list, unfortunately. I zipped through it in no time; here are some of the messages that caught my attention (I haven’t checked the research literature on any of them).

A question that health science has studied is what is the relationship between levels of exercise and health benefits. The latest answer seems to be that a minimum of about three hours walking per week has a huge benefit for health. Any exercise beyond that level certainly is beneficial, but the rate of benefit decreases, and eventually hits a maximum at some extreme point. Beyond that exhaustion point you increase your chances of, say, dying from a virulent flu, or damaging your heart in some way. That point, and how it is reached, varies from person to person.

Intesive exercise is better (for health). Jogging beats walking, sprinting beats jogging. Short burst of vigorous exercise can have the same, or more, benefits than far-longer periods of gentler exercise. These short bursts should be, say, ten sets of 60 seconds, with rests in between of a minute or two.

Don’t stretch before exercise. It has been shown in a number of sports that stretching decreases performance. Tight hamstrings can be better for running that flexible hamstrings: they snap back into place faster. Instead just warm up gently – get the appropriate muscles moving.

Flexibility is largely genetic. We can adjust it a bit by streching, yoga, but in fact if we find that we can stretch farther, then often it isn’t because our muscles are more flexible – rather we have learned to tolerate, mentally the discomfort of the stretch.

Exercise burns calories, so exercising should make us lose weight. There are a few reasons why it doesn’t. The underlying reason, it seems, is that our body has a desire to reach a kind of stable weight, whatever that may be. If we use up calories by exercising, then it makes us more hungry to compensate. Also, it makes us more static, lethargic than usual after exercise, so we don’t burn as many calories outside exercise than we otherwise would. A losing battle, as the author calls it! It’s important to stress here that exactly how the body behaves varies from person to person, and is affected by genetics and the environment – and your own choices.

There are limits to how much your body compensates for loss of calories though. Experiments appear to indicate that beyond a certain limit you don’t compensate as much. Gradually, you work your way towards fitness, providing you behave sensibly. Don’t lounge around outside exercise.

If you want to improve in sport, then you have to keep pushing yourself a little further. Keep a log, time yourself, and so on. I can’t be bothered with that.

Resistance training compliments aerobic training. Weight training and similar activities has multiple benefits: longevity, brain, and it helps with running and other aerobic activities. It is particularly important for keeping control of the function of our bodies as we age. Yoga gets a special mention as an effective, diverse form of resistance exercise. And squats are praised too.

There’s a small section on barefoot running. I’ve been doing this recently, now and then. The idea, roughly, is that wearing shoes encourages us to run on our heels, and land heavily, rather than land lightly on our soles. Experimental evidence on harms/benefits is mixed. One problem is that if you remove your shoes you may continue to land heavily on your heels, but without shoes there you could injure yourself. I sometimes run in the evening with no shoes. I find that I tend to run on my soles more than I otherwise would, partly because I’m a bit nervous about landing on something sharp.

Strength training is the best way to avoid injury.

Exercising helps your brain. It helps slow memory loss. It helps rebuild brain cells. It helps reduce stress. Important for children as well as adults.

Movement is important. Don’t sit at your desk writing blogs that nobody reads. Get up, for the sake of your cells. Walk, walk, walk, as we were designed to do. Sitting for long periods can have significant long-term detrimental effects on our health. So stand up instead, and don’t stay still.