FULL RANGE OF MOTION
According to a study by Brazilian researchers performing weight-training exercises through a full range of motion produces greater strength gains then partial range of motion exercises. Strength gains were still achieved with partial range of motion but not nearly as significant.
In the study Full ROM training was 50% more effective than restricted range of training or partial movements.
Incorporating full ROM also assists in keeping the body free of injury and can increase flexibility.
Remember to breathe and consult a personal trainer if you are beginning any exercise program.
Journal of Strength and Conditioning Research, 26 2140-2145 2012