Strength Training Using Motor Imagery
Body sense can produce the same strength gains with fewer repetitions
Posted September 12, 2011
Body sense is the ability to feel our movements, body sensations, and emotions in the present moment. In this blog, I've written a lot about how body sense can enhance our enjoyment of and gains from exercise. Runners who scored higher on tests of body sense, for example, used less oxygen, ran faster, and with less build-up of muscle tension. Taking frequent rest breaks during running (so-called interval training) leads to better oxygen consumption, more cardiac output, increased speed and agility, and better fat metabolism. I think these interval training effects are related to an increased tendency to pay attention to our bodies as they calm down and cool down, which then spreads to more body sense while doing the activity. In fact, slowing down any physical activity - from tai chi, to yoga, to athletic and musical practice - increases body awareness, reduces stress and pain, and gives people more confidence in their movement.
So, in different types of movement activities body sense adds to the benefits and in turn enhances our desire and willingness to re-engage in the activity. The more we feel ourselves, the better we feel and the more likely we are to repeat what makes us feel good.
A study published in August 2011 in the journal Frontiers in Movement Science and Sport Psychology, adds another way in which body sense can enhance your workout: by imagining muscle contraction in place of actually doing some of the reps. Forty-three healthy sports students (20 female) did arm and leg isometric contractions on machines with real weights three times per week for 4 weeks. They were randomly assigned to one of 4 groups. One group did only real muscle contractions. Three groups interspersed real and imaginary contractions in ratios of either 1 real to 3 imaginary, 2 real to 2 imaginary, or 3 real and 1 imaginary. The students "were instructed to imagine maximal contraction efforts as vividly as possible, using kinesthetic imagery ('you should imagine the sensation associated with a contraction effort, but your muscles must stay relaxed')." Observers checked to make sure that the imaginary contractions were not accompanied by small muscle movements. At the end of each workout session, the students rated the vividness of their kinesthetic images on a scale from 1 (no imagery could be performed) to 5 (vivid imagery could be performed). There was also a control group who did no exercise at all.
Results show that all of the groups did better on a test of maximum voluntary muscle force than the control group. In addition, there was no statistical difference between the all real contraction group and the groups that did imaginary contractions part time. The bottom line: imaginary contractions when used in place of real contractions during a workout can have the same payoff. This was true even if imaginary contractions were done on up to ¾ of the reps.
What has this got to do with body sense? In order to do an imaginary muscle contraction well, you have to pay attention to your body. Try it now. Imagine doing an isometric contraction without actually moving or tensing your muscles. It might be easier if you did a few real ones first, after which you would have a better body memory of how it feels. The clincher for me was that this study also found that the student's reported vividness of the motor imagery was correlated with strength gains. In other words, the better a person is at feeling the sensations of muscle movements in their body, the more likely the imaginary work will help to build their muscles.
Past research on motor imagery shows that the same brain areas are activated when imagining a movement compared to actually doing it. These motor areas overlap with mirror neuron areas in the motor cortex, making us very adept at imitating another's movements or feeling an empathic response in our own bodies when watching someone move expressively. It also follows that being more in tune with our own body sense actually enhances our ability to sense into another person's body.
Could we improve our strength or agility simply by imagining and not actually doing the work? Arm chair sports, like watching a sporting activity on TV, is not going to make you gain strength, lose weight, or feel more fit because you are not likely to be doing motor imagery while watching, except maybe in having the motor image of getting up to get a drink or a snack while being glued to the chair.
In what way, then, would your own motor imagery of watching a sport help your body? In order for this to work, you have to take a single movement (like a golf or tennis swing), "replay" it in your own body sense multiple times, and then take it onto the playing field and try it out. This is how coaching works. You watch the coach demonstrate or tell you how to execute an action, and then you try it in on your own body. You have to pay attention, in slow motion, to all the places you are executing the movement properly and where you are not.
So, you need body sense both in the imaginary phase and in the action phase. I wish the people who did that study on imaginary weight lifting had the students rate the vividness of their body sense while doing the actual contractions. I'll bet that the imaginary contractions enhanced body sense during the real exercise periods, which may be the real explanation for the effect. But, you could try it yourself and see what happens.