Here’s another post summarizing stuff I’ve been reading and thinking about recently.
Music and exercise
Earlier this week I went out for what was supposed to be an easy three mile run. It was in fact easy for the first half, but then the music changed. My Spotify playlist shifted from reggae to Metallica. When Enter Sandman came on I picked up the pace, and halfway through Master of Puppets I was racing like a berserker. I finished with the fastest time of the summer.
This made want to do a little research into the connection between music and sport performance. It turns out that there has been a lot of research. A recent review found evidence that listening to music during exercise enhances physical performance, improves physiological efficiency, reduces perceived exertion, and, not surprisingly, makes the whole thing a little bit more fun. USA Track and Field banned the use of headphones during official races in 2007 because it wasn’t safe. People were mad.
Parkour robots
Here’s a video that is fun and scary at the same time.
Why are the robots doing parkour? It’s a logical way to test for generalized movement dexterity.
Glycemic index
A new study tries to determine whether glycemic index matters for obesity prevention and weight loss. (Glycemic index is a number between zero and 100 which represents the relative rise in blood sugar two hours after consuming a particular kind of food.)
The answer, based on analysis of more than 43 observational studies and 30 meta-analyses of RCTs, is no, not really. 70% of the observational studies found that high-GI diets were correlated with either the same or better body mass index than low-GI diets. And the analysis of the controlled trials concluded that low-GI diets were generally no better than high-GI diets for reducing body weight or body fat.
How many studies have been done on this nutritional variable? At least 10,000.
Monkeys choke under pressure
This study reports that:
we trained three rhesus monkeys to perform a difficult reaching task in which they knew in advance the amount of reward to be given upon successful completion. Like humans, monkeys performed worse when potential rewards were exceptionally valuable. Failures that occurred at the highest level of reward were due to overly cautious reaching, in line with the psychological theory that explicit monitoring of behavior leads to choking.
In other words, the monkeys choked. Interesting that monkeys are self-conscious enough for this to happen. I speculate that most animals (e.g. dogs) are not. For more on why self-conscious monitoring of your movement leads to poor performance, check out my recent podcast with Nick Winkelman.
Confusion about variability
The concept of variability in motor performance technique can be confusing because there are many different kinds of variability to which the term might refer. Some aspects of variability are good and we want to increase them, while others are bad and we want to reduce them, and yet others should remain at some goldilocks level of not too much and not too little. The video below from Rob Gray, at his excellent Perception and Action Podcast, has some clear distinctions that appear in some helpful graphics in the first four minutes of the video. These are:
Variability in practice. You want some, so that you are not just repeating the same drills over and over, but not so much that you are out there playing a different sport each day.
Variability in the non-essential elements of good movement technique, which we often want to increase, giving us more ways of performing under different conditions. For example, in a golf swing it is not essential that your backswing have a certain length, and you want to be able to hit good shots with many different length backswings.
Variability in the essential aspects of good technique, which we want to reduce as much as possible, so that certain fundamentals are executed without fail on each repetition. In golf this might be a certain position of the body during impact.
Variability in the outcome of the movement, which we want to reduce as much as possible, meaning that we always have a successful outcome on each repetition.
Rob also usually defines Nikolai Bernstein's concept of a synergy in terms of variation: a synergy occurs when a variation in one technical variable is compensated by a variation in another variable to produce a stable outcome. For example, a basketball shot that involves more or less wrist flexion on each repetition might (note: I’m just speculating here) produce a constant fight path if those changes are compensated by more or less elbow extension at the same time. So maintaining the synergy or the relationship between the two variables would be essential, whereas the absolute values of the variables would be nonessential.
More on functional versus non-functional variability here.
An impressive leap from a bobcat
A case study in back pain
Adam Meakins, who is a physical therapist and very good writer and educator about back pain, recently injured his back while deadlifting, caught the injury on video, and has been publishing daily videos of his recovery, along with his expert rationale on which treatments he is using and not using. Unfortunately, he's received a great amount of unsolicited and questionable treatment advice from other therapists (much of it provided with an insulting tone.) Bronnie Lennox Thompson, who I interviewed here, has some valuable comments about it. She asks:
Why are there so many clinicians offering unsolicited opinions, without examining Adam, and without listening to his preferences, and without referring to the evidence?
… I’m struck with the thought that many people just don’t know what to say – and so offer advice because that’s one way to deal with their own disquiet at helplessness. Clinicians, we need to develop better skills at managing our OWN emotional responses. We need to develop greater skills at sitting with our uncertainty. We need to stop leaping in with unsolicited advice that we offer just because we’re not comfortable doing nothing.
Excellent points.
Love the jumping robots. Robot movement seems to have advanced a huge amount in the last few years.