by Nils Osmar

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• Published November 7, 2025. © Nils Osmar 2025.
• This article should not be taken as medical advice.  See full Medical Disclaimer
• Thanks to Claude.ai, ChatGPT, and Perplexity.ai for consultation, fact-checking and verification of accuracy.

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Three months ago, I developed tendinitis in my right arm, and also have some indications of it in my left. The most likely culprit is a marathon project I was working on that had me typing 10-12 hours a day for several months straight, which resulted in a repetitive stress injury. In short, I overdid it.

I’m 72 years old at the time that I’m writing this… I’ll be 73 in a month and a half. I’ve been lucky in many ways; I’m still mentally sharp and clear and physically strong. One thing I have going for me is that I have been working out regularly for the past three years, doing resistance training and HIIT. But I’ve had to take a break from the resistance training due to the tendinitis, and have started noticing some signs that I may be losing muscle mass. Not a lot, but enough to be aware of it.

This sent me looking for alternatives. Could I maintain my strength without putting strain on my inflamed tendons?

To be clear, there are numerous things that we can do in my situation; one is to make sure that we’re eating a high protein diet, rich in the amino acids that support muscle protein synthesis; I’m trying to eat at least 1 g of protein per pound of body weight. I’m also eating collagen along with vitamin C, and taking hyaluronic acid and some other supplements.

When I was brainstorming about other things that I might do, I remembered reading about studies suggesting that mentally visualizing exercise might actually produce measurable strength gains. I found some articles and studies online, and asked Claude AI to help me verify that I was understanding them correctly, and that the research was still considered valid. Happily, both were true.

The Cleveland Clinic Study: Strength Gains Without Moving a Muscle

One landmark study came from the Cleveland Clinic Foundation in 2004. Researchers recruited 30 healthy young volunteers and split them into groups. Some would mentally practice finger abduction exercises. Others would visualize elbow flexion. A control group did nothing. A comparison group did actual physical training.

The mental training protocol was simple: 15 minutes per day, 5 days per week, for 12 weeks. No weights. No movement. Just focused mental practice.

The results were striking. The finger group increased their strength by 35%. The elbow group gained 13.5% to 22% (sources vary on the exact figure). The physical training group, as expected, saw the largest gains at 53%. But the mental imagery groups achieved real, measurable strength increases without ever contracting a muscle.

How Is This Possible?

The gains aren’t coming from building new muscle tissue. You can’t grow muscle fibers through imagination alone. Instead, the strength increases come from neural adaptation – essentially strengthening the command signal from your brain to your muscles.

When you lift a weight, you’re not just working your muscles. You’re training your nervous system to recruit motor units more efficiently. A motor unit is a motor neuron and all the muscle fibers it controls. The more motor units you can activate, and the more efficiently you can fire them, the stronger you are.

Mental imagery training appears to strengthen these neural pathways. You’re rehearsing the motor command, reinforcing the brain-to-muscle signal, without the physical wear and tear of actual exercise.

This is particularly relevant for people in my situation – dealing with injury or temporary inability to train. During the first two weeks of immobilization or reduced activity, strength losses come primarily from reduced neural activation rather than muscle atrophy. Mental imagery can help maintain those neural pathways until you can resume physical training.

Not All Mental Imagery Is Created Equal

Here’s a critical detail: the type of imagery matters enormously.

Researchers distinguish between internal motor imagery (IMI) and external imagery. With internal imagery, you imagine the exercise from a first-person perspective. You don’t just see yourself doing it – you feel yourself doing it. You sense the muscle tension, the effort, the squeeze of the contraction, as if you were actually performing the movement.

External imagery is like watching yourself on video. You see yourself from the outside, but you’re not experiencing the sensations.

The difference in results is dramatic. Studies show internal motor imagery producing strength gains of 2.6% to 136.3%, while external imagery only yields 4.8% to 23.2%. One study that found no benefits from mental imagery likely failed because participants were inadvertently using external rather than internal visualization.

This isn’t about casually daydreaming about being strong. It’s about kinesthetic rehearsal – mentally executing the movement with the same focus and intensity you’d bring to an actual workout.

What the Research Shows Works Best

Based on the studies, here’s what appears most effective:

Smaller muscle groups respond better. Distal muscles like fingers and hands show greater gains than proximal muscles like shoulders or legs. This makes sense given the higher density of neural connections to our hands and fingers.

Consistency matters. The protocols that worked used 15-minute sessions, 5 days per week, for 8-12 weeks. This isn’t a quick fix.

Internal imagery is essential. You must feel yourself performing the movement, not watch yourself doing it.

Don’t overdo it. Interestingly, mental imagery training can cause mental fatigue. Continuous repetition of motor imagery can fatigue your central nervous system, potentially decreasing performance. The 15-minute protocol may represent a sweet spot.

The Immobilization Studies

A 2014 study from Ohio University looked specifically at people who couldn’t use their muscles due to injury. Participants had their arms immobilized in casts. One group spent 11 minutes, five days per week, visualizing flexing their immobilized muscles. The control group received no special instructions.

When the casts came off, the mental imagery group was twice as strong as the control group. This isn’t just about maintaining strength – it’s about significantly reducing the losses that normally occur during periods of forced inactivity.

For someone in my situation – or anyone dealing with tendinitis, post-surgical recovery, or other temporary limitations – this suggests a practical tool for damage control.

Limitations and Contradictions

Science works best when we look at the full picture, including studies that contradict the ones we’ve found promising.

A 1998 study by Herbert and colleagues found no significant strength gains from mental imagery. Researchers now believe this was likely because the instructions led participants to use external rather than internal imagery. This is actually useful information – it shows us that technique matters. Do it right, and you see results. Do it wrong, and you might see nothing.

It’s also worth noting that combining mental imagery with physical practice appears to be more effective than either alone. Mental imagery isn’t a complete replacement for physical training when that’s possible. It’s a tool for when physical training isn’t an option, or as a supplement to your regular routine.

What I’m Trying

I’ve started incorporating internal motor imagery into my daily routine. Fifteen minutes, focusing on the muscle groups I’d normally hit with resistance training. I close my eyes and mentally execute the movements – not watching myself do them, but feeling the contraction, the tension, the squeeze.

For my upper body, I’m visualizing bench presses, rows, and overhead presses. For my arms, curls and tricep work. I focus particularly on my hands and forearms since those seem to show the strongest response to mental training.

To be clear, I’m approaching this as an experiment. I don’t know yet how effective it will be. But the research is solid enough that it seems worth trying. Most importantly, it doesn’t interfere with the healing process for my tendinitis.

I’m also not abandoning physical training or therapy. I’m finding modified movements I can do that don’t aggravate the inflammation. Fortunately, I can still do some resistance training, as long as I limit it to my lower body. For my upper body, the mental imagery gives me something productive to do to push back against what might otherwise be some muscle loss.

My Protocol

If you want to emulate what I’m doing, the research suggests there may be benefits in this protocol:

Duration: 15 minutes per session

Frequency: 5 days per week

Length: At least 8-12 weeks to see significant results

Technique: Internal, kinesthetic imagery. Close your eyes. Feel yourself performing the movement. Experience the muscle tension, the effort, the contraction.

Don’t watch yourself from outside – inhabit the movement.

Focus: Smaller muscle groups may respond better than larger ones. Hands and arms before legs and torso.

Warning: This can be mentally fatiguing. If you feel mentally exhausted, that’s real CNS fatigue. Don’t push through it the way you might with physical training.

An N=1 experiment: In addition to the above, I’m also doing some “forbidden” exercises such as “bicep curls” in which I do move my arms through the actual range of motion, but with no actual resistance — imagining, and letting myself feel and visualize resistance. Just moving my arms in this way is not contraindicated; the problem would come if I added extra resistance.

I can say that it feels great. Whether it’ll be beneficial, or more beneficial than simply letting myself “feel” the exercise without any motion, I don’t know. It’ll be interesting to see the results, If any.

An Adjunct, Not a Replacement

I should be clear about what this is and isn’t.

This isn’t a replacement for proper resistance training when that’s available to you. The physical training group in the Cleveland Clinic study still saw larger gains than the mental imagery group.

This isn’t going to build new muscle tissue. The gains come from neural adaptation – better recruitment and activation of the muscle you already have.

This isn’t going to work if you’re just vaguely thinking about exercise. The internal, kinesthetic focus appears to be essential.

As a tool for maintaining strength during injury, illness, or other periods when physical training isn’t possible, the evidence suggests it’s worth exploring.

A Limitation to be Aware Of

After writing an initial draft of this article, I wanted to verify something important: whether anyone had specifically studied mental imagery for specific situations like mine — maintaining strength while working around an overuse injury like tendinitis. AI’s are particularly skilled at helping answer questions like this.

The good news is that there is some research which strongly supports the use of motor imagery for preventing muscle loss and maintaining strength during periods of reduced activity. Studies have demonstrated that motor imagery during arm immobilization can significantly reduce strength loss and help maintain the neural pathways between brain and muscle. Research programs lasting 4 weeks to 6 months, with sessions of about 15 minutes, have been shown effective not just for maintaining strength, but also for reducing pain perception and fear of reinjury.

Motor imagery has been successfully used in rehabilitation for conditions including shoulder impingement syndrome, where it helped alleviate pain and enhance mobility.

To be clear, most published studies have focused on complete immobilization (like when a limb is in a cast), post-surgical recovery, or acute injuries. My situation – using mental imagery to maintain strength while working around tendinitis rather than being completely immobilized – represents a reasonable extension of these research findings rather than something that’s been extensively studied in its own right.

The underlying mechanisms are the same. Whether you’re completely immobilized or strategically reducing activity to allow inflammation to heal, you’re facing the same challenge: reduced neural activation leading to strength loss. Mental imagery addresses that neural component directly.

So while I’m applying these techniques in a context that’s slightly beyond what’s been formally studied, I’m doing so based on what I believe to be sound scientific principles. The research gives me confidence that this approach is worth trying, even if my exact situation hasn’t been the subject of a dedicated clinical trial.

Visualization of this sort is of course not a cure-all; if you need physical therapy, it’s important to get it. But the evidence suggests that it can be valuable for people who can only tolerate lower levels of activity intensity due to physical limitations or injuries.

Should You Try It?

If you’re dealing with an injury that’s keeping you from your normal training, or if you’re just curious about the mind-body connection, from my perspective, it might be worth trying. The worst-case scenario is you spend 15 minutes a day in focused meditation-like practice. The best case is you maintain neural pathways and minimize strength losses until you can return to full training.

I’ve started exploring this myself. If it works, I’ll share an update. And if you try it, I’d love to hear about your experience.

Take care, and feel free to drop a line in the comments below with your thoughts. With warm regards, Nils

Bibliography

• Ranganathan, V.K., Siemionow, V., Liu, J.Z., Sahgal, V., Yue, G.H. (2004). From mental power to muscle power—gaining strength by using the mind. Neuropsychologia, 42(7), 944–956. Cleveland Clinic Foundation study of mental imagery and strength gains in healthy subjects.​
• Herbert, R.D., & colleagues. (1998). No significant strength gains from mental imagery: likely explanation is the use of external rather than internal imagery. Reference available via article meta-analyses and psychology databases.​
• Clark, B.C., Mahato, N.K., Nakazawa, M., Law, T.D., Thomas, J.S. (2014). “The power of the mind: the cortex as a critical determinant of muscle strength/weakness.” Journal of Neurophysiology, 112(2), 321–329. Ohio University immobilization study showing imagery preserved strength during casting.​
• Slimani, M., Chaabene, H., Miarka, B., Chamari, K., & Tod, D. (2016). Effects of mental imagery on muscular strength in healthy and patient participants: a systematic review and meta-analysis. Journal of Sports Science & Medicine, 15(2), 233–250. Reviews effectiveness and variations in mental imagery techniques.​
• Lebon, F., Collet, C., & Guillot, A. (2010). Benefits of motor imagery training for muscle strength. Frontiers in Human Neuroscience, 8, 319. Neural mechanisms underlying imagery-related strength gains.​
• Hatzigeorgiadis, A., et al. (2011). Mental imagery and performance enhancement: combining with other cognitive techniques. Journal of Sport Psychology, 29(3), 185–202. On packages/interventions combining imagery with self-talk, relaxation, and goal setting.​

Not medical advice

This article is not intended as, and should not be taken as, medical advice. I’m not advising that people eat any particular diet or take any particular supplement(s), just reporting on what I’m doing. Supplements, like medications and other interventions, can have side effects; I would encourage people to research both possible benefits and side effects before starting on any supplementation regimen, and consult with a medical professional about any issues which might have a medical component.  See full Medical Disclaimer

Other resources

• My Youtube channel Pathways to Longevity
• My Facebook group: Anti-Aging and Life Extension, 

About the Author

Medical Disclaimer

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