As you walk along, you experience lower back pain. Why is this happening? Here is a summary of the analysis:
- This article analyzes the relationship between walking and lower back pain.
- The main muscles responsible for maintaining an upright posture are the hamstrings, gluteus maximus, erector spinae, and transversospinalis muscle groups.
- The large superficial muscles of the body are responsible for major movements and posture, while the smaller superficial muscles coordinate movement, and the small deep muscles provide fine-tuning.
- If the large muscles of the legs and back are either too tight or too loose, it can lead to muscle strain and pain.
- If the large muscle groups become imbalanced, it can overwork the smaller stabilizing muscles around the spine, causing muscle strain and pain.
- Chronic overuse of the smaller muscles can reduce their flexibility, leading to misalignment of the pelvis and lumbar spine during flexion and extension, which can cause radiating nerve pain.
- It is recommended to seek assistance from professional experts to test and help train the proper muscle function, or you can try to change your walking gait and relearn how to walk.
We learn how to walk as early as 1-2 years old. Discussing the graceful, upright, rhythmic, and joyful aspects of walking can be a topic for another time. In this piece, we will continue the discussion from the previous two articles and explore why some people experience lower back pain while walking.
Try walking with your eyes closed on a straight path; some people will start to veer off course after just 5 steps, while others may make it 10 steps before drifting. Given enough space, they may even end up back at the starting point. Disaster movies often feature scenes of characters getting lost and circling back to their point of origin in the fog or darkness, and reality TV game shows use blindfolded walking challenges to create unexpected outcomes.
The reason we can’t walk perfectly straight is that the human brain has a natural lateral bias. Nearly everyone has some degree of asymmetry in their body structure—the eyes, ears, hands, and feet all have an innate sidedness. Muscle strength is also often uneven. In our day-to-day activities, we rely primarily on visual cues to subconsciously correct our direction and maintain balance. These minor adjustments happen automatically, without us even noticing.
Experts typically define “normal” blindfolded walking as when the end position is within 15 degrees of the starting point. We don’t need to strive for a perfect zero deviation, but understanding how to minimize the degree of veering can help improve overall body balance and stability. This, in turn, reduces the unnecessary energy expenditure and strain on the body that can lead to issues like lower back pain over time.
【Looking at daily behaviors】
Left-handed people make up about 10% of the population. The differences between left-handed, right-handed, and ambidextrous people can lead to variations in the rotation, flexion, and lateral bending of the thoracic spine. It can also result in differences in the strength of the corresponding legs.
Around 20% of the population is left-footed, with the left foot being more agile and the right foot acting as the primary support. The differences between left-footed and right-footed people can cause an uneven distribution of the upper body’s weight onto the two femoral heads at the hip joints. The muscles in the two legs also develop differently; the dominant support leg has stronger extensor muscles, while the swinging leg has stronger flexor and rotator muscles. This can be seen in actions like kicking for a shot, jumping for a shot, or standing at ease.
Have you noticed which is your dominant support leg? Where is your center of gravity when standing relaxed? Which leg do you use to step over a threshold? In activities like long jump, high jump, or single-leg hopping…
When we walk, our two legs alternate in supporting our weight, shifting the center of gravity from side to side. When the support leg is in the support phase, is the step taken by the other leg larger or smaller?
The step is larger. This is because the support leg is more stable, and the flexor muscles of the opposite side are also stronger.
In other words, the alternating step lengths when we walk have a noticeable difference: one foot takes a deeper step, while the other takes a shallower step. This asymmetry is often imperceptible to us.
【Looking at the anatomical perspective】
The main muscles responsible for maintaining an upright posture in the human body include:
- The hamstring muscles in the legs and the gluteus maximus in the buttocks
- The erector spinae muscle group and the transversospinalis muscle group in the back
The large superficial muscles of the body are responsible for the primary movements and posture. The smaller, more superficial muscles are responsible for coordination. And the deep, small muscles are responsible for fine-tuning adjustments.
If the large muscle groups become imbalanced, the smaller muscles will become overworked and imbalanced as well.
In other words, the major muscle groups that keep our body upright and stable include the hamstrings, gluteus maximus, and back extensors. These large, superficial muscles do the heavy lifting. Smaller, deeper muscles provide fine motor control and coordination. But if the big muscles are not working in harmony, it puts strain on the smaller, supporting muscle groups.
The relationships shown in the diagram are antagonistic (different colors) and synergistic (the same colors).
Ipsilateral antagonistic relationship:
When the hamstring muscles and the gluteus maximus muscles are shortened,
The ipsilateral erector spinae muscles and the transversospinalis muscles are in an extended state.
Contralateral synergistic relationship:
When the hamstring muscles and the gluteus maximus muscles are shortened,
The contralateral erector spinae muscles and the transversospinalis muscles are in a shortened state.
In other words, the muscles on the same side have an antagonistic relationship; when the hamstrings and gluteus maximus contract, the back extensor muscles on that side lengthen. But the muscles on the opposite side have a synergistic relationship; when the hamstrings and gluteus maximus contract, the back extensor muscles on the other side also contract.
This ipsilateral antagonism and contralateral synergy help to maintain balance and coordinate movements of the trunk and lower body.
【From the picture】
Starting with feet together, as the left (dominant) foot lifts and swings forward, the right (non-dominant) leg becomes the single support limb. Due to the relatively weaker stability of the non-dominant support leg, the left swing phase time and amplitude are more limited, resulting in a shorter step length for this half-cycle.
Then, as the right foot leaves the ground and the right leg begins to swing, it moves from the posterior side to the midline and continues swinging forward. With the left leg providing relatively better support, the step length for this half-cycle is larger.
Over time, this inconsistency in step length between the two sides can exacerbate an imbalance in hip joint positioning, with one side experiencing relatively more extension and the other side experiencing relatively less extension.
Looking at the force diagram, when the hip experiences extension, the pelvis will tilt posteriorly and the thoracic cavity will flex anteriorly. An imbalance in the degree of hip extension on the two sides means the motion angles of the pelvis and thoracic cavity will also become unbalanced between the sides.
In summary, the asymmetry in the swing and support phases, leading to step length differences, contributes to hip, pelvic, and thoracic imbalances that can persist over time if not addressed. The force diagram analysis helps explain how these kinematic asymmetries manifest in the rotational mechanics of the trunk.
【What impacts does this imbalance produce?】
》The right hip extension angle is smaller than the left side, and the right hamstring and gluteal muscle contraction is less than the left hamstring and gluteal muscles.
》The right pelvic tilt angle is smaller than the left side, and the right erector spinae and quadratus lumborum muscles are less extended than the left erector spinae and quadratus lumborum muscles.
》The right thoracic lateral flexion angle is smaller than the left side, and the right abdominal muscle contraction is less than the left side.
》The right-back muscles are shorter than the left-back muscles.
》The right abdominal muscles are longer than the left abdominal muscles.
》The right side is more prone to intervertebral disc protrusion anteriorly, while the left side is more prone to posterior intervertebral disc protrusion.
In summary, even if the fourth and fifth vertebrae are both protruded as diagnosed by MRI, the symptoms presented by ten patients may not be entirely the same, as the relative muscle strength of the ten patients is not exactly the same and the nerves being compressed are not identical. The stronger muscles will directly or indirectly pull the bones, like the winning side in a tug-of-war, and the tilted angles of the ten tug-of-war games will not be exactly the same.
The muscles that have been chronically elongated are weak and flabby, like an overstretched rubber band (the non-supporting leg’s gluteal, posterior thigh, and abdominal regions), while the chronically contracted muscles are like very thick, tightly tensed springs, tensed to the point of being unable to contract further. By understanding the differences on both sides, we can regain balance through differential training. Weak, flabby muscles should be strengthened with appropriate resistance training, while contracted, tense muscles need to be released through massage or yoga. Of course, we can also consciously adjust our center of gravity during walking to balance the forces, make the stride lengths more similar, and coordinate the footsteps.
The force theory opposes exercising while listening to music and watching TV and opposes uniformly exercising the same movements.
Observe yourself, choose the exercise methods that match your current body imbalance, and focus on feeling your body during the exercise process, gradually learning to control your body’s movements and integrating these movements into your daily life.
Exercise should be scientific, and life itself is exercise.
Post time: May-31-2024