Study type: Randomized controlled trialConfidence: Low

From Mental Power to Muscle Power—Gaining Strength by Using the Mind

Ranganathan VK, Siemionow V, Liu JZ, Sahgal V, Yue GH

Year2004

Sample sizen=30

JournalNeuropsychologia

AuthorsRanganathan VK, Siemionow V, Liu JZ, Sahgal V, Yue GH

Evidence is still limited and needs further study

Summary

Healthy young adults were assigned to imagined training of finger abduction (n=8), imagined training of elbow flexion (n=8), a no-training control (n=8), or an actual physical-training group (n=6), performing 12 weeks (15 min/day, 5 days/week) of imagined maximal voluntary contraction. Imagined training alone increased finger-abduction strength by ~35% and elbow-flexion strength by ~13.5%, accompanied by rising EEG-derived cortical potentials that paralleled the strength gains. Gains did not match the physical-training group (~53%), and the control group showed no significant change. This is a small study (~8 per group) and cannot objectively verify how faithfully participants performed the mental contractions.

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DOI: 10.1016/j.neuropsychologia.2003.11.018

Key Findings

Key findings

Key point

1
Imagined training alone increased finger-abduction strength by ~35% and elbow-flexion strength by ~13.5% (both statistically significant)
2
The physically trained group gained ~53%, well beyond the imagined-training groups — mental training did not match real training
3
Cortical potentials derived from EEG rose in parallel with the strength gains, supporting a central-nervous-system adaptation
4
The no-training control group showed no significant change. Limitation: small groups (~8 per arm), and adherence/effort during imagined contractions could not be objectively verified

Related Research

Related research

Randomized controlled trial

Strength Increases From the Motor Program: Comparison of Training With Maximal Voluntary and Imagined Muscle Contractions

Journal of Neurophysiology, 1992

Thirty healthy adults (n=10 per group) were randomized to actual maximal contraction training, imagined contraction training, or no training (control) of the fifth-digit abductor muscle for 4 weeks (5 sessions/week). The imagined-contraction group increased strength by about 22% (vs. ~30% for the actual-contraction group and 3.7% for controls), while electrically evoked twitch force was unchanged in all three groups — indicating no muscle hypertrophy occurred. The gains without hypertrophy suggest the strength increase from imagined training reflects central nervous system (motor program) adaptation rather than a muscular change. This is a single, small study (n=10/group) limited to one small muscle (the fifth-digit abductor).

View study details

Randomized controlled trial

The Power of the Mind: The Cortex as a Critical Determinant of Muscle Strength/Weakness

Journal of Neurophysiology, 2014

In this RCT, 44 healthy young adults were randomized to 4 weeks of wrist-hand immobilization alone, immobilization plus daily mental imagery of strong contractions, or a no-intervention control. The immobilization-only group lost an average of 45% of wrist-flexor strength, while the immobilization-plus-imagery group lost only about 24% — roughly half as much. Measures of voluntary activation impairment and cortical inhibition were also smaller in the imagery group. The study population was healthy young adults; replication in real fracture/post-surgical patients or older adults, and direct measurement of muscle atrophy, were not part of this study.