As a child, I remember sitting in my backyard watching my father give my older brother a boxing lesson. "Keep your feet planted and use your body," he would say. I thought to myself, 'why is he talking about planting the feet and using the body, when you punch someone with your fist?' At that time I thought you had to have strong hands, or at least strong arms to land a great punch. In the years since, I've learned power doesn't come from the arms, but from the body.

At 2005, APTA Combined Sections Meeting, the symposium "The Female Athlete's Shoulder" covered different aspects of rehabilitation and conditioning of the female athlete's upper extremities. One part of the presentation emphasized the role of core stability in the rehabilitation and over all performance of the upper extremities.
During the symposium, I found myself returning to the backyard of my childhood when one speaker, Barb Hoogenboom, MHS, PT, SCS, ATC, started talking about core stability. 'Why is she talking about the core and trunk in an upper extremity symposium?' I wondered. Then I quickly recalled my lesson: Power comes from the body. Her experience has led her to conclude that a strong core is the foundation for strong performance.
"My colleagues and I call it the 'butt and gut,' which is just a catch phrase we use to describe the relationship between the trunk, spine, pelvis and the proximal lower extremities," said Hoogenboom.
The 'but and gut' is the centerpiece to optimal performance and function, according to Hoogenboom, in anyone from the elite athlete to a patient recovering from hip replacement surgery. "Core stability is inherent to human function. To be able to ambulate and do activities of daily living, you need to utilize the muscular stabilizers of your trunk. To me, it's just a part of big-picture thinking for every client and every patient."

CORE IMPORTANCE
When Hoogenboom was asked to speak at the CSM symposium, she felt her job was "to paint a picture of how this core is so important to function of the distal and proximal upper extremities."
To do this, Hoogenboom emphasized two points. She credits the work of Ben Kibler, MD, from Lexington, KY, for her knowledge of the first concept, the kenetic chain. "The kenetic chain is the route by which energy and forces are transmitted from your lower extremities, through the core and then out through your upper extremities," said Hoogenboom.
"For example, in the windmill pitch in softball, your feet are on the ground but you have to transmit the energy through your core to your upper extremity and then to the softball," she explained. In athletics, according to Hoogenboom, when the kinetic chain is disrupted by core weakness, performance can suffer.
The other point Hoogenboom described as "an old, well-accepted notion that comes from PNF, or proprioceptive neuromuscular facilitation. It's the concept that proximal stability is a necessary prerequisite for distal mobility and function."
Hoogenboom researched the PNG literature and found information addressing how the upper extremities build on proximal stability from the core - or the "butt and gut." "We won't have good aim with softballs or positioning of our arms in a pool when swimming if we don't have a stable core from which to work," she said.

THE RIGHT MUSCLES
In athletes, it is imperative to be in top form in order to succeed in competition. Training and conditioning are part of the process of reaching that level of fitness. However, many athletes will make the mistake of looking to the mirror to see what progress their bodies have made. Eventually, the athlete's goals can become aesthetic in nature, rather than performance-driven. Hoogenboom warned, however, what you see is not always what you get.
She said people tend to spend a lot of time focused on their physical presentation and fail to consider function. "Society tell us that, aesthetically, a flat stomach or a sculpted abdomen is beautiful - and I would be hard-pressed to say that it doesn't look good. But the function of that is less than optimal," said Hoogenboom.
The rectus Abdominus, she explained, is the muscle group responsible for the six-pack look. It is meant to flex the trunk. "Many back authorities and people who treat the spine would say that we all too often flex it too much and thereby place excessive forces on the lumbar spine," said Hoogenboom.
"In sit-ups, the rectus Abdominus dominates and diminishes input by the obliques and other important muscles," she said. "I hear of athletes who do thousands of sit-ups and crunches in a week. My question is, does it really help and is it important to performance? The predominant answer is that it really doesn't."
The other important muscles Hoogenboom mentioned are the transverses Abdominus, the multifidi, the pelvic floor and the psoas. While working each of these may not have as dramatic results aesthetically as the rectus Abdominus, function and performance can be improved by simply paying closer attention to them during training.
Hoogenboom describes the transverses Abdominus as a major physical stabilizer of the core. It has been described as functioning like a corset or a weight lifting belt. This muscle is one of the most important muscles in core stability, yet, according to Hoogenboom, it is one of the most underutilized.
"The transverses Abdominus is the first active muscle in the stabilization of the trunk, and it pre-activates before upper extremity tasks. It's what we call anticipatory postural control," she said. "It's continually active with all activities of the upper extremity and the trunk, but also very important in the upper extremity motions, like shoulder lifting or shoulder flexion. That shows it is a real postural stabilizer," she said.
Working hand-in-hand with the transverses Abdominus are the multifidi, short segmented muscles between vertebrae. The performance of one is linked directly to the performance of the other. Together they have the job of supporting the spine during movement. "Multifidus muscles complete the ring of stability. They are so important in their stabilization function that in an injured person, they will atrophy or become less able to perform their function," said Hoogenboom.
Another muscle group the transverses Abdominus seems to work closely with is the pelvic floor. "There are studies that show that with increased pelvic floor muscular activity," said Hoogenboom.
Finally, the psoas is a very important muscle for positioning and stability of the lumbar spine in flexion and extension. "If your psoas is really tight, you'll be stuck in an extended position of the lumbar spine, which disadvantages other muscle groups from working. In fact, it disadvantages your multifidi and makes it harder to contract your transverses Abdominus," said Hoogenboom..

GETTING THROUGH
While all of this information is helpful in knowing what needs to be done for optimal performance of the upper extremities, the trick is communicating the benefits to patients or clients.
"It's a hard sell. You feel like you're a used-car salesman sometimes," said Hoogenboom.
It becomes particularly tough when the individual is far more interested in developing those six-pack abs. When telling clients about working the core for upper extremity performance, Hoogenboom said, "sell them on function and performance."
An analogy that seems to work for Hoogenboom is that of tools. The hammer is a tool that was specifically developed for use when putting a nail through a dense material, like a piece of wood. One would not use a hammer to cut the piece of wood into two. That would take a lot more effort and would likely end up rendering the wood useless. Avoiding this simply requires knowledge of how to use the tools.
In our bodies, the rectus Abdominus is the muscle group that has the specific purpose of flexing the trunk, but it is not going to be ideal to concentrate on for performance and function. "Knowing your core and knowing where you are in space, you'll build your performance and build yourself into a better athlete. And you'll reduce the possibility of injury," said Hoogenboom.
In working with sports clients, Hoogenboom explained, the concept of "building a better athlete" seems to be a good way to communicate the importance of the butt and gut. Simply put, "if the muscles that looked good visually did the job, the people with six-pack abs wouldn't have injuries, but they do," she said.
Sometimes, however, rather than tell them more about the benefits, Hoogenboom will show them why it is important by simply lowering their center. For example, "if you were to do an exercise for the upper extremities and are able to use your lower extremities and your core properly, you may feel it in your arm and trunk a little bit. But if I take your legs out of it by putting you on your knees on a piece of foam, it is amazing how you feel your abs and stabilizers start to work to allow that motion to be performed properly and not place undue stress on your shoulder," said Hoogenboom.
She said putting athletes on their knees on foam is her favorite way of exemplifying the importance of the core in the performance of the upper extremities. "If you ask a tennis player to serve a ball from her knees, it's almost impossible, because her legs are so important and the transfer of force from the legs, to the trunk, to the arms is what makes a serve have velocity, force and direction," she explained.

FUNCTION FOCUS
Athletes often can be the easier clients to get through to, because they have goals of performance and are generally more in tune with their bodies, according to Hoogenboom. The non-athletic individual can pose a challenge to therapists who are trying to emphasize core strength.
Even for an athlete, it can sometimes be difficult to focus on the core muscles Hoogenboom holds in such high regard because they are seated so deeply in the trunk, particularly the transverses Abdominus. "Adding to that, in more heavily deconditioned people with more abdominal adipose, it's harder to find the transverse abs, but it's no less important," she said.
Regardless of their patient's conditions or diagnoses, however, Hoogenboom emphasized that therapists should incorporate core stability as best they can when appropriate.
"It's the basis for good posture. So even if you're sitting at a computer all day, you still have to have a reasonably stable core to avoid injury. And when I do work with older people who desire to be more active than they are, like by playing tennis or golf, we work a lot with strengthening the core. It's just about seeing that person in the big picture," she said.

RESOURCES
Hodges, P.W., & Richardson, C.A.(1997). Feedforward contraction of transverses abdominis is not influenced by the direction of arm movement. Experimental Brain Research , 114, 362-370.
Richardson, C., Jull, G., Hodges, P., & Hides, J. (1999). Therapeutic exercise for spinal segmental stabilization in low back pain. London: Churchill Livingston.
Kibler, W. (1998). The role of the scapula in athletic shoulder function. American Journal of Sports Medicine, 26(2), 325-337.
Source: The Nation's Physical Therapy Newsmagazine "Advance for Physical Therapists and PT Assistants" May 23, 2005 Vol. 16 No. 12