Mental imagery involves envisioning oneself performing a physical activity without actually doing it. It is currently used by many high-level athletes to enhance their physical performance. While the method is well-accepted for maintaining focus and consistency of technique, its use has recently been examined for improving strength as well.
In a study by Lebon, Collet and Guillot in the Journal of Strength and Conditioning Research (vol. 26, no. 6, pp. 1680-1687, 2010) male college athletes who had not been weight training were put on a program of bench-press and leg-press training 3 times per week for 4 weeks. The only difference between the training groups was that the imagery group visualized doing each exercise during the between-set rest periods while the control group performed another thought task.
Both groups improved in strength and the number of repetitions they could perform with 80% of the maximal weight they could lift during pre-training tests. However, the imagery group improved 26% in leg press strength vs. 21% in the control group. Repetitions with 80% of pre-training max increased 92% in the imagery group vs. 79% in the control group. Both between-group differences were statistically significant. There were no differences between training groups as to changes in bench-press performance and neither group showed any significant increases in muscle-size.
It is known that the strength gains resulting from the first few weeks of training are largely due to neuromuscular adaptations rather than muscle-size increases. Mental imagery may enhance the neuromuscular component of strength change and thus the most applicable to novice lifters. It is not clear why the method was effective for the leg press but not the bench press.