Body weight exercises, including pushups, depend on progressively disadvantageous positions to increase the resistance placed on the worked muscle groups, since adding weight would cease to make it a body weight exercise. Pushups are normally used to develop chest, triceps and shoulder muscles, but can be tweaked to target the forearms specifically by changing body position and modifying the hand’s grip style or contact with the ground.
Body weight exercises are performed without the addition of weight. In order to increase the resistance placed on the targeted muscle group, the trainer must either increase the repetitions, which develops muscular endurance, or make the repetition more difficult by adding to the range of motion or disadvantaging the muscle. The latter adjustments focus on increasing muscular strength and result in muscle growth.
The forearm muscles are responsible for controlling hand and wrist movement as well as grip strength. To target these muscles in a pushup motion, the body must be positioned to require additional work from the hands to remain stable. This can be accomplished by placing one hand on a raised object such as a medicine ball or performing a pushup in the decline position.
However, Christopher Sommer, a professional gymnastics instructor, recommends doing planche pushups. This exercise repeats the pushup motion but without the advantage of having feet on the ground, with all the weight resting on the trainer's hands, according to DragonDoor.com.
Placing additional body weight on the hands forces the wrists into an uncomfortable position and may strain the muscles in the hands and wrists. One way to avoid this problem is to perform pushups and planches with pushup handles. These elevated grips let the trainer adjust the wrist position and reduce stress placed on the joints. Another method is to perform fingertip pushups, which require the trainer to develop gripping power in order to support body weight.
Performing pushups or any exercise for the sole purpose of building forearm muscle may in fact diminish the trainer’s strength gains in that area. The body is a unit, and muscle groups are connected to one another in order to perform tasks. In his Colorado experiment, reported in the September 1973 edition of "IronMan," Aurthur Jones argued that while individual muscle groups can be worked in isolation, multijoint exercises focusing on increasing large muscle groups are more effective at producing strength gains in all related muscle groups.
Using different body positions and grip styles can place more resistance on the forearms, but the best way to increase forearm strength is to focus on improving upper-body strength overall. Pushups are a good way to improve forearm strength because they target major muscle groups in the arms, chest and back. Using positions of disadvantaged leverage or performing fingertip pushups further increases the level of difficulty for greater strength gains.