The same procedure was used for the bench press. Core muscle
activation was measured by using electromyography (EMG; it measures
the “electrical activity of muscles”). As the instability of the surface
increased and less weight was used, the recruitment of core musculature
decreased.
A 2012 Norwegian study published in
The Journal of Strength and
Conditioning Research
measured the force output of leg and core
muscles in isometric squats performed on a stable surface (floor), power
board, BOSU ball, and balance cone.
The study examined from stable to extremely unstable. An isometric
contraction simply means the muscle does not move while force is being
produced. In this case, the athletes squatted with maximal force against
a bar they were unable to move, with their thighs slightly above 90
degrees. The bar contained an electronic device that measured the
amount of force the athletes could produce. The electrical activity of
muscle was also measured. These measurements insured there was no
chance of bias or an incorrect formula being used.
The results showed force production decreased 7 percent on the power
board, 19 percent on the BOSU ball, and 24 percent on the balance
cone. Recollect that this is a contraction where the athlete is not moving;
adding movement and transition phases as in a stable squat would
further decrease force production with instability. Quadriceps had the
greatest electrical activity with stable squats.
Athletes such as Alpine skiers that are required to compete on unstable
surfaces can derive benefits from unstable surface training. In addition,
stability ball work is effective with abdominal exercises and
rehabilitation, although there is no need to perform traditional strength
exercises with barbells or dumbbells on stability balls. The benefits are
limited and risk for injury is high.
The bottom line is that to gain lean muscle and get stronger, you need to
use heavy resistance on a stable surface.
Medicine Balls
Medicine balls
usually range between 2 and 18 pounds. They are an
excellent means of training for upper-body speed-strength. Medicine
balls are made of soft material (leather, rubber, and stuffing), so they can
safely be caught, repelled, or thrown. While you can throw a dumbbell, it
would be inadvisable to try to catch one, and you certainly would not try
it at high speed. Another advantage of medicine ball training is that
compensatory acceleration training can be done with literally no inertia
because when you release the ball, the resultant stress on the joints is
far less.
medicine balls:
A medicine ball (also known as an exercise ball, a med
ball, or a fitness ball) is a weighted ball roughly the diameter of the
shoulders (approx. 13.7 inches), often used for rehabilitation and
strength training. Medicine balls are usually sold as 2-25 lb (1-11 kg)
balls and are used effectively in plyometric weight training to increase
explosive power in athletes in all sports. Some medicine balls are in the
form of weighted basketballs.
