The Elastic Limits of Human Performance

What defines our ability to sustain a prolonged stressful effort

I never really liked the word ‘endurance’ which comes from Old French ‘endurer’ meaning "make hard, harden; bear, tolerate; keep up, maintain." Not very cheerful is it?
But I am changing my mind thanks to Alex Hutchinson, author of Endurance: Mind, Body and the Curiously Elastic Limits of Human Performance. I love this book first because it is extremely well-researched and second because it highlights how important words are.

Muscles don´t really ‘fail’

Have you ever trained so hard that you felt your muscles were failing (the so-called train to failure practice)? In fact, muscles don´t fail and the limits we encounter when we train hard aren’t due to failing muscles but to our brain wanting to protect us. Our brain doesn´t want our muscles to fail. It wants to keep a reserve of energy for emergencies, so it controls how hard we can work out. In other words, in a long endurance challenge, our muscles are not incapable but unwilling.

Positive thoughts get us further

Words in our head, just like a smile or frown, are influential. They affect our sense of effort and how far we can push. Samuele Marcora gathered 24 volunteers to do a cycling test to exhaustion. Then 12 of them were taught how to use positive self-talk before they did another similar test two weeks later. The other 12 weren´t. What happened? In the second test, the self-talk group last 18% longer and their perceived effort was also less pronounced. In another test, cyclists were shown happy or sad faces. Those who were shown happy faces cycled longer.

When I feel tired while running, I repeat the mantra used by Mark Divine, a retired SEAL officer and trainer of elite athletes (not saying I am one of them!). It just makes me smile and I do get a little energy boost. Here it is: Looking good. Feeling good. Ought to be in Hollywood! Give it a try next time you feel low on energy while exercising and see if it works for you too!

Thirst vs dehydration

I always believed that dehydration increases core temperature, which we want to avoid. But if only has a limited impact. What matter however are external weather conditions as well as metabolic rate. Anyway, according to physiologists to improve endurance and performance, we should focus on avoiding thirst, rather than dehydration (of course if we ignore our thirst, then we ultimately run the risk of becoming dehydrated).

When I go running, I always take a small bottle of water and drink a sip about every 1 or 2 km depending on the weather. I was very glad to read that a later study found that swallowing small mouthfuls of water - like I do - doesn’t make any difference to the overall hydration level and yet boosts performance by 17 percent (OMG I would be even slower if I didn’t take a sip regularly!)

Here again, perception is key. Thirst increases our sense of perceived effort. Apparently it is the cooling effect of the water down the throat that quench our thirst. Experiments where some athletes were given water via a tube down the throat while others could drink it normally showed that we need to feel the liquid to feel less thirsty.

…anything that moves the ‘effort dial’ in your head up or down will affect your endurance, even if it has no effect on your muscles or heart of VO2 max. (Alex Hutchinson, Endurance)

I simplified a lot and there is far far more in the book - including a lot of opposite views on the role of the brain, muscle fatigue, protein, carbs and fasting, oxygen, hydration etc… so I would highly recommend reading the book if you are interested in the topic.

But what I would love to find out about is what dies it mean for people living with MS. Can we also develop endurance following similar approaches? Can we move the ‘effort dial’ too? Should we? Aren´t muscles actually failing in some cases due to MS? I will dig into the huge research field of physical activity and MS and hope to find some answers. If you have come across any book or articles on the topic, please share. Thanks.

Have a wonderful week

Much love

Veronique