Conducting exercises such as lifting weights in the proper manner is crucial to both safety and getting the full benefit from the particular exercise. WellPath Coordinator Andy Weiler said that many common exercises are done improperly, and he offers insight on how to correct that. Here, some sample exercises are illustrated by Salt River Pima-Maricopa Indian Community Council Member Tom Largo.
For example, Weiler said moving a free weight (dumbbell, kettlebell) horizontally does not actually provide the resistance necessary to promote muscle strength.
“Often I observe exercisers moving free weights in a horizontal motion. This is common as part of an exercise movement such as bench flys or ‘Arnolds,’” Weiler said. “To evaluate the effectiveness of this movement, we need to consider some simple physics and exercise physiology.”
Physics: The force of gravity is measured as weight. Gravity is a constant force that pulls downward. So when we lift a free weight in a manner that changes its elevation (hence the term “lifting”), then we are working against gravity. Gravity provides the resistance necessary to make our bodies adapt to weight lifting. The adaptation is physiological and the desired end result is increased strength and muscle size.
When we move a free weight horizontally instead of vertically, then we are not working against gravity (other than to prevent the weight from falling). So Council Member Largo is lifting the dumbbell from the floor to the height pictured, but when he brings his arms together in toward the midline of his body, and then moves the dumbbells out toward his shoulders, there is nothing really resisting this motion.
To provide resistance and help gain strength for horizontal movement, exercise scientists use a variety of equipment (cables, elastic tubing) that allows the horizontal movement to cause vertical lift of weights. In the example below, Councilman Largo uses a cable system to provide resistance against his moving his arms horizontally toward the midline of his body. The entire time he moves his arms horizontally the weight is being elevated and he has to overcome gravity to put the weight in vertical motion. So if he is using 40 lbs. of weight, then as he moves his arms toward the midline of his body he must provide the same force (effort) required to lift the 40 lbs. In fact, for every inch he moves his arms horizontally, the cable is lifting the weight 1 inch.
So the question often arises: Why do we feel our muscles getting tired when we perform horizontal motion with a free weight?
Exercise Physiology: “There are three main ways we classify muscular contraction, which is the tension caused by muscle when it is working,” Weiler said. “One way is when a muscle contracts and shortens, another is when a muscle contracts and lengthens, and the third way is when the muscle contracts and there is no movement. This is called isometric contraction.
Isometric contraction increases strength even when the muscle isn’t changing length and it does t cause fatigue and other changes (example: increased blood pressure). However, isometric contractions do not cause much improvement in strength when the muscle is shortening or lengthening (during movement). Any time you are moving a joint, the muscle is either shortening or lengthening.
So in our example, the muscles required for Council Member Largo to hold the dumbbells in the fixed position are working isometrically. The muscles eventually become tired of holding the weight in the air. So this exercise will help Council Member Largo be stronger holding weights in the air but won’t help him actually lift weight. The exercise isn’t achieving the intended purpose; Council Member Largo isn’t getting any stronger moving his arms horizontally.
When he uses the cable system, the muscles required to move his arms horizontally now must overcome the gravity of the weight, as horizontal movement is causing a lifting of weights. He becomes stronger moving his arms horizontally.