1-arm, variable-angle, incline dumbbell press and trunk stabilization on a Swiss ball
Video on June 9, 2013
Resistance: 105 lb. dumbbell
Swiss ball diameter: 55 cm (22 in.)
Bodyweight: 181 lbs. (82.3 kg)
Ratio of resistance to bodyweight: 0.58 (58%)
Similar concept to the 1-arm supine dumbbell press on a Swiss ball, this movement has significant advantages to conventional incline presses with either dumbbells or a barbell with an incline bench. First, significant yaw is introduced by the synergistic combination of asymmetric loading (use of one dumbbell) and instability from the Swiss ball. Second, by varying hip position via hip extension/flexion, you can modify the angle of your spine with respect to gravity effectively changing the incline angle and, consequently, the recruitment contributions from the deltoids, triceps, and pectoral engagement. A supine (i.e. “bench press”) has an angle of 0 degrees and a shoulder press has an angle of 90 degrees whereas an incline press is 45 degrees and sometimes, with a pin selector, adjustable to 30 or 60 degrees. In contrast, this movement encompasses an infinite range of angles in real-time just by moving the hip angle even during the course of a single repetition.
This movement has different properties than the supine press version (0 to 25 degree spine angle) when the external load is great enough. In this video the load is almost 60% of bodyweight and the spine is around 45 degrees. Also, in previous videos I was using a 65 cm Swiss ball and in this one it is 55 cm. The increased load along with a smaller diameter ball transforms this movement from a incline press with stability challenges to primarily a trunk stabilization/balance movement with the press being secondary. If you watch my trunk and legs they are working hard to maintain equilibrium and, additionally, because the point of support for the ball has shifted from the lower cervical/upper thoracic spine area to mid-thoracic, extreme effort must be made to maintain a stiff trunk through prolonged isometric contraction along with partial holding the breath to stiffen the diaphragm like when doing heavy squats or deadlifts. Yaw is increased from the higher load and the longer lever arm from the smaller ball’s lower contact point on the spine to the center of mass of the dumbbell increase the level of difficulty significantly (the load could cause thoracic hyperextension if not resisted). This movement would have value if you just held a heavy dumbbell in the extended, locked position for 20 seconds. Perhaps something to tinker with and develop.
A different perspective on the evolution of weight training
Imagine a hip flexion/extension continuum where at one extreme you have maximal hip flexion where your legs are almost touching your chest. You would be in a deep squat and your spine would be close to straight up like the bottom position in the Olympic snatch. This would be close to a “shoulder press”. Now, at the other extreme, if the hip joint is extended to where a line through the hip and shoulder joints is parallel to the floor you would have a “bench press” (provided the ball diameter is correct to accommodate this position). Would an “incline bench” have been invented if Swiss balls made for heavy resistance training were invented first? If function weighs in, the answer is no. This is the single most important movement you can perform in the pressing movement repertoire if efficient and general force production to the real-world is your objective.
Mentally the most striking aspect of this movement is the powerful connection between the pressing movement (the control of the velocity and position of the dumbbell in space) AND awareness of your hip position AND micro-positioning of your feet to maintain balance and counteract torque from the effects of yaw. Place your opposite hand on the rib cage of the loaded side to increase the asymmetrical load. Your entire body is very actively engaged with a 100% duty cycle: no resting! Because you are (or can be) on a steep angle with a large degree of hip flexion, please realize you are in a deep squat (below parallel) with a dumbbell overhead with a spine angle of 45 degrees. This is not really an “incline press”, is it? In other words, if you cleaned a heavy dumbbell and then squatted to below parallel and stayed there while pressing would you call that a seated press? In a normal incline press, either seated or standing, you get zero integration of dynamic upper and lower body control; all you are doing is statically pressing two dumbbells or a barbell. There is nothing else happening worthy of mention. This is even more pronounced if you are using some kind of pressing machine which further isolates you from real benefits. What is the outcome of doing that besides big pecs?
addressing yaw and roll
As with any movement where yaw is a potent factor affecting whole-body performance, unrecoverable roll can come into play suddenly if your center of mass breaches your base of support. Given the summation of forces generated by the asymmetric load (your center of mass is deviated to the side of the single dumbbell and the heavier it is the more the impact) plus yaw (the dumbbell moves laterally with respect to your centerline because the ball rolls side-to-side), this produces a torque with rotation about the axis running through your spine causing roll. If this happens you need to know your exit strategy in advance which is to dump the dumbbell to the floor. Don’t fight it, let it go! Make sure this can be done safely so that you and no one else gets injured. To minimize roll, modify your base of support (the position of your feet and the contact point of the ball with the floor compose the base of support) with hip abduction (your knees move from the midline to outside your body from the hip joints, see the video).
addressing shear forces
Additionally, the coefficient of static friction matters greatly in this movement because of shear forces. Why and where does shear arise? In contrast to the supine version of this movement where your bodyweight presses vertically (i.e. a normal force with respect to gravity) against the Swiss ball and in alignment with the ball’s surface to the floor (your back is not going to “slide” against the ball and the ball is not going to “slide” against the floor), this movement introduces a force vector component that is tangential to two pairs of contact surfaces (shirt to ball and ball to floor) called the shear force component and is vital to the integrity and safety of performing this movement. If your shirt were superglued to the ball and the ball were superglued to the floor, then the materials under shear may undergo strain (become damaged or deform). But without the superglue this will not happen because the shear force will exceed the force corresponding to either the coefficient of static friction of your shirt to the ball or the ball to the floor. What this means is that you must wear a shirt and the floor cannot be smooth and the ball surface should not be smooth.
So what happens? As you approach a vertical spine angle the normal force vector component becomes negligible and the tangential force vector component is dominant. Yaw becomes a big problem because of its role in shear. Either the ball could slide against the floor causing unrecoverable roll, or, if your body slides against the ball this will cause unrecoverable roll. The shear results in a slide (coefficient of static friction is violated) causing an acceleration in a lateral direction which breeches base of support causing roll. In the video I am using a Swiss ball that is burst proof to 350 lbs. and has a rough surface (see image).The newest version has a 500 lb. rating. The floor is made of rubber. Be careful. Extreme physics are in play here and physical laws like the coefficient of static friction and Newton’s laws are not negotiable.
For more information:
BIONX SUPERMODEL (pdf)