Normal office chairs are notorious for negatively impacting your posture, especially if you are sitting in them improperly. Slouching in your chair may also lead to a decrease in your core strength and a number of other health problems we’ll explore further in this article.
The solution? It may be replacing your office chair for a stability ball.
The Biomechanics of Sitting
Just like all our movements, sitting requires the activation and relaxation of certain muscles, and it stresses different bones. The parts of the body that are most studied regarding sitting posture is the spine and back (lumbar region) and the pelvis. The hamstring muscles also influence sitting posture, however.
The biomechanics of sitting can change significantly depending on the chair type and posture. When we stand freely, all of our weight is transferred to the floor through our feet. When we sit down, most of the weight transfer to the floor is shifted from our feet to the seat pan, armrests, and backrests. This transfer gives our feet a feeling of relief.
When we sit, we naturally tend to slouch a little to feel relief from standing. Our lumbar region is concave and curved toward the stomach, giving the appearance of “slouching.” In this posture, technically called lordotic, the vertebrae and discs are thicker toward the front of the body rather than toward the back of the body to cushion the increased pressure on this part of the vertebrae. Also, the sacrum, which is the lower part of the spine fixed to the pelvis, is angled forward.
Since the sacrum is connected to the pelvis, any rotation of the pelvis affects the vertebrae of the spine.
If the pelvis is rotated forward slightly (b), the lumbar spine curves to better maintain an upright posture. However, a backward tilt can lead to an increased flattening of the lumbar spine. This can increase kyphosis (sometimes referred to as hunchback or roundback), which is a spinal disorder where the spine has an outward curve and this results in the development of abnormal rounding of the upper back (c).
As you can see in the image below, compared to relaxed standing, both upright and slouched sitting have smaller angles. The smaller the angle in prolonged sitting, the bigger the risk for back pain and injury.
The hamstring muscles also influence sitting posture and the position of the spine. They extend from just above the knee to the pelvis, meaning they cross the hip and knee joints. As a result, the extensibility and the strength of hamstrings have an impact on back posture as well.
In fact, in people who have lower back pain related to working for long periods in front of a computer, their hamstring muscles tend to have increased activity. This means that people with back pain tended to have more tense hamstring muscles than those without back pain.
One study examined the effects of stretching the hamstrings in the workplace on posture. Researchers found that hamstring stretching exercises effectively increased hamstring extensibility, resulting in a more aligned spinal curve and a more favorable pelvic tilt.
Another study found that athletes who had injured their hamstrings had poorer lower back posture. Both of these studies are examples of the correlation between hamstring health and posture.
Experts tend to categorize sitting postures into three types: anterior, posterior, and middle.
In the anterior (forward leaning) posture (A and B in the figure below), the center of gravity is placed in front of the ischial tuberosities (“butt bones”) over the thighs, which can cause strain in the lower back. Here, the floor supports more than 25 percent of body weight.
In the posterior (backward leaning) posture, the center of gravity is behind the ischial tuberosities. This is the posture preferred for resting, but over time it can cause pain in the pelvis.
In the middle (relaxed, unsupported) posture, the center of gravity is directly above the ischial tuberosities. The floor supports 25 percent of body weight, which is ideal, and the spine is straight or only slightly curved forward. This is the ideal sitting position for posture and back health.
Since sitting statically for long periods of time is linked to low back pain, researchers have examined the connection between different postures and sitting styles and the development.
One study examined the impact of twenty minutes of sitting in different ways on trunk range of motion, muscle activity, and proprioception, which is the ability to feel how your body is oriented in the space around you.
The first sitting style was static slouched (unmoving with the spine curved forward), the second style was upright (unmoving with muscles activated to sit upright), and the third style was supported sitting with a backrest. The study found that the slouched position had the lowest activation of the abdominal muscle.
This study illustrates why it is important to remain with your back straight up, regardless of the seat of choice.
With the correct use of a stability ball, you spend your time actively balancing, so your body may naturally form a more correct posture. For some people, this can alleviate any back or core strain that you may have previously experienced sitting in a chair.
Besides just improved posture and core strength, below we explain five other benefits that you may experience by replacing your office chair with a stability ball.
Keep in mind that the stability ball isn’t for everyone. In fact, if you are more likely to slouch forward and lean on your desk rather than keep your muscles activated while you use a stability ball, it may present more disadvantages, including discomfort, than advantages for you. However, the advantage of the stability ball is that it can potentially improve your posture by keeping your muscles engaged, as long as you make the conscious effort to do so.
What is the correct way to use a stability ball for sitting?
Keep your knees hip-width apart.
Keep both feet on the ground.
Straighten your spine and roll your shoulders back (you may need to adjust the position of your keyboard and computer) so that your neck is not bent.
As you sit, make slight circular or side-to-side movements with your buttocks and back to keep your abs activated.
The Benefits of Using a Stability Ball
Experiencing the negative effects of sitting in an office chair? Here are five benefits of sitting on a stability ball:
Burn Extra Calories: It's simple, really: The more we move, the more calories we burn. The more time sitting actively on the stability ball, the more you move.
Relieve Back Pain: Unfortunately, sitting on a stability ball isn't going to miraculously alleviate any pain you are experiencing. However, if you take a moment to stretch your back muscles while sitting on the stability ball, you may be able to relieve some of the pain you are experiencing.
Tone Core Muscles: While simply sitting on a stability ball will not tone your muscles, having the stability ball on-hand will make it much more practical to take a moment to do exercises to tone your abs and obliques. Back health is closely connected to core muscle strength. Research shows that core strengthening helps to reduce hip muscle imbalance and helps to reduce low back pain.
Breathe Better: When you are slouched over, your lungs are shortened, so you breathe in less air. One innovative study published in 2019 examined the impact of sitting posture on lung function. The study found that when sitting posture maintained a neutral lower back curve people had much greater air capacity and overall improved lung function. As long as you are using the stability ball properly and your muscles are activated to have a neutral sitting posture, it can help you breathe better.
Induce the Inspiration to Stretch: The stability ball, in addition to functioning as your seat, can also be a tool to help you stretch to relieve any strain you might feel. It can also provide added support when you want to get a deeper stretch that you may not have been able to perform otherwise.
Other Suggestions to Improve Posture
Choosing the right seat is just one of the things you can do to improve sitting posture and overall back health. Other things you can do on a regular basis include:
Stretch regularly. Stretching your hamstrings on a daily basis in the workplace generates a more aligned spine and a more favorable trunk inclination.
When you stand, make sure you are distributing your weight evenly on each foot.
Get up to walk at regular intervals.
Strengthen your thigh muscles.
Stretch and rotate your neck.
Sit actively. Sitting on a stability ball naturally encourages you to sit actively, but you can also sit actively in chairs and on benches by reminding yourself to center your trunk over your spine.
Use correct back support. This is particularly helpful when you are sitting in a chair. It is important to invest in good back support, choosing seating that naturally helps you sit in a neutral, yet supported, position so you can feel relaxed while sitting upright.
When you are texting or reading, keep your cellphone or book at eye level so your neck isn’t curved downward.
Avoid wearing high heels. Use shoes with good arch support on a regular basis and save your high heels for a special night out.
Choose a firm mattress and a low pillow.
Remember that sitting on a stability ball isn't going to be a panacea for the eight-hour workday. And, while using a stability ball can alleviate a lot of the strain you may experience when sitting in an office chair, many experts still argue whether it has the advantages people seek, and some research has shown that sitting on an exercise ball may have disadvantages, such as spinal shrinkage. The truth is, sitting all day—regardless of sitting in a chair versus on a stability ball—can negatively impact your health.
For best results, switch back and forth between using a chair and a stability ball. And, don't forget to stand up throughout the workday to mitigate any possible health concerns associated with sitting for a long period of time.
This article was first published by the American Fitness Professionals & Associates.