Keiran has been my personal trainer for more years than I can remember. I am trying to convince him that I no longer need to do pushups, swats and weights. Instead, I can do it all in my imagination.

Exercising in your imagination may be fine but does it improve your muscles? It appears from a number of studies that it just might.

One of my pet hates are hip abductions. Raising one leg sideways and then pulsing it. There are even machines designed to train that specific set of muscles. It is these machines that pay a key part of one of the studies.

Improving Hip Muscles.

Researchers put together groups of college athletes. They played football, basketball and rugby. The different sports were randomized into three groups. The first group were assigned to a regular training session to improve their hip abduction muscles. The second group were a “control”. They carried on with the normal training regime common to all the groups. The third group were the most interesting. They were the “imaginary” group. The group was not just to imagine that they were doing an abduction exercise. Instead, they were to imagine the muscles and that they were contracting maximally.

Each participant was tested for strength at the beginning and the end of the study. They used a hip flexor machine. The subject stood next to the padded bar and attempted to raise his left leg sideways. Weights were added to the bar. The final weight achieved was taken as the pre and subsequently post measure of strength. Measures were also taken pre and post of blood pressure and heart rate.

The training took place over the next two weeks. It consisted of five sessions per week. Participants in the imaginary and physical groups attended sessions at the gym. An “imagination” participant mentally envision himself using the hip flexor machine. For four sets of eight repetitions, each set being followed by a 60 second period of rest. They were to imagine increasing the lifted weight by five pounds each day. Those doing the physical exercises performed the same routine but on a real machine.

Mental and physical training both produced substantial increases in strength. 32 Ib and 36 Ib respectively. The control treatment yielded a nonsignificant increase of only 6 Ib. Mental results were lower than actual exercise but not statistically so. The systolic pressure of both “exercised” groups dropped relative to the control group pre versus post. So too did the resting heart rate.

How does mental strength influence physical strength?

A separate study offers some insights. In this case the muscle to be strengthened was much smaller. They focused on the ability of the little finger of the dominant hand to press sideways. Respondents laid their hand palm down in a fixed position. They pressed their little finger sideways as hard as they could on to a pressure sensitive plate. This constituted the “pre-test”. Measures of heart rate and blood pressure were taken. This time during the real or imaginary exercise. The finger was also given an MRI scan to measure the size of the muscle pre and post.

The mental training lasted for 12 weeks. Each week the participants attended for five sessions a week of fifteen minutes. Participants were instructed to perform mental contractions of the fifth finger. They were to abduct it for 5 sec followed by a 5 sec rest. They repeated this fifty times with a two-minute rest after the first 25. Again, they were not just to imagine doing the exercise. Instead to imagine stimulating the muscle to its maximum extent as they had done in the pre-test. The physical training involved participants using the same machine as in the pre-test. They had the same training schedule as the mental group.

The “mental exercise group” increased the strength of their finger by 35% compared to a control group. The physical exercise group did better at 53%. Both groups showed increased muscle size as measured with the MRI. During the exercise both groups showed increased blood pressure and heart rate. Average heart rate during the mental exercise increased from an average of 72bpm to 78 bpm. Not bad given how small the muscle.

Particpants also had electrodes attached to their finger and brain. This assessed both the stimulus sent to the muscle and activities in the brain associated with muscle action. There are two ways in which muscle strength can increase. The muscles themselves can become stronger. Alternatively, the intensity of the stimulus to muscle can increase. "Mental training” had increased the power of the activation signal sent from the brain to the muscle. They tracked participants for six weeks after the end of the training. The muscle strength of the mental group increased further. It lasted until the end of measurement.

Is Kieran out of a Job?

The results are only indicative. Even with the mental exercise it seemed that you need a trainer. Someone to motivate the task. If I am going to a training session with a trainer why only do it mentally? Kieran is too good to waste.

There is a more serious point. There are people who cannot undertake physical training. They may have a chronic disease. They may be recovering from an operation. Many of them are older. A controlled amout of mental exercise may allow them to maintain the muscle tone that they need when they recover. All the evidence shows exercise improves health and mortality. Does “mental exercise” help? It costs nothing to try.