Push or Pull? What Your Back Does (Especially If It Hurts!)

Hey there! Ever wondered what’s *really* going on with your back when you’re pushing that heavy shopping cart or pulling something stubborn towards you? Especially if you’ve got that nagging, chronic low back pain that just won’t quit? Well, I stumbled upon some pretty interesting research that dives right into this!

This study basically took a peek at how our spines behave – things like posture, how “stiff” they are, and how our muscles are working – when we’re doing simple pushing and pulling tasks while standing. They compared folks who don’t have back pain with those who do, specifically looking at two common patterns of chronic non-specific low back pain: the “flexion pattern” (FP) and the “active extension pattern” (AEP). It’s like trying to figure out if different types of back pain mean your body uses a different strategy to get the job done.

They had people stand, push, and pull against a light load – just 15% of their body weight, nothing too strenuous. Then they measured all sorts of things: the curves in their spine, how much their lower back shifted, how stiff different parts of their spine were, and the electrical activity of some key trunk muscles like your abs (Rectus Abdominis – RA, Internal Oblique – IO) and back muscles (Erector Spinae – ES, Lumbar Multifidus – LM).

What Happens When You Push vs. Pull?

So, what did they find when comparing pushing and pulling? Turns out, the task itself makes a difference!

When people were *pulling*, their lower back (lumbar spine) tended to shift more backwards compared to when they were pushing. Think of it like your lower back tucking under a bit more. This also meant their lumbar curve (lordosis) got smaller, and even their upper back curve (kyphosis) got smaller compared to just standing upright.

Interestingly, pulling also made the Rectus Abdominis (your main abs) work harder than pushing did. This makes sense – pulling often involves a bit more trunk flexion or bracing.

Digging Deeper into Muscle Activity

Now, when they looked at the different groups (no pain, FP, AEP), things got a bit more specific. While most muscle activity patterns were pretty similar across the groups during these low-load tasks, there was one standout: the AEP group showed significantly *higher* activity in their Internal Oblique muscles (part of your abs) across *all* tasks compared to the folks without pain.

This is pretty interesting because it hints that even when doing simple tasks, people with certain types of back pain might have slightly different muscle strategies going on, even if their overall posture looks similar to someone without pain in this specific low-load scenario.

What About Stiffness?

Okay, so posture and muscle activity change depending on the task and maybe slightly depending on the pain pattern. What about spinal stiffness? This is important because stiffness relates to how stable your spine is.

Here’s a bit of a puzzle: the study *didn’t* find significant differences in spinal stiffness between standing, pushing, or pulling tasks. They also noticed a *lot* of individual variation in stiffness measurements. The researchers thought this high variability might have “washed out” any task-specific effects. They also speculated that maybe the effects of posture changes (like less lordosis in pulling, which might make the joints less “locked”) and muscle activation (like the increased RA activity in pulling, which might increase compression and stiffness) might be cancelling each other out.

So, Push or Pull?

Based *specifically* on the finding that pulling seemed to result in greater lumbar translation (that backward shift), the study authors suggested that maybe, just maybe, pushing might be slightly preferable to pulling for manual handling tasks because it might induce less “shear” force on the lower spine. Shear force is like a sliding motion between the vertebrae, which isn’t always great.

However, they were quick to point out that this finding was a bit different from some previous studies that used different methods (like biomechanical models based on EMG) which suggested pushing might cause *more* anterior-posterior shear. So, the jury’s still a bit out, and it might depend on *how* you measure things!

Why Didn’t We See More Differences?

You might be wondering, if these folks have different back pain patterns, why didn’t their posture and movement look *way* different from the asymptomatic group during these tasks? The researchers had a few ideas:

• Low Task Demand: The load (15% body weight) was pretty light, and none of the participants reported pain *during* the tasks. Pain is known to change motor control patterns, so maybe the task wasn’t challenging enough to provoke those pain-avoidance strategies.
• Similar Disability Levels: The groups had similar levels of self-reported disability, which might mean the symptomatic groups in this study weren’t experiencing severe limitations that would force drastically different movement patterns.
• Sample Size and Type: The study had a relatively small sample size (39 people), and they were described as relatively young and fit. This might not represent the typical person with chronic LBP, who might be older or have a higher BMI.

Essentially, it seems that for low-load tasks without pain, people with these specific types of chronic LBP might be able to perform them using strategies that look quite similar to those without pain, perhaps by recruiting muscles slightly differently (like the AEP group’s IO activity) to achieve a similar outcome without pain.

The Road Ahead

This study gives us some cool insights, but it also opens the door for more questions. The authors suggest future research should look at:

• The effect of *repetitive* pushing and pulling – because daily life isn’t just one push or pull, right? It’s often many.
• Using higher loads, closer to safety limits or what people encounter in real work/life.
• Including people with other types of LBP patterns (passive extension, lateral shift, multidirectional) to get a fuller picture.
• Using more advanced technology, like high-density EMG, which can give a more detailed map of muscle activity than traditional methods.
• Studying larger, more diverse groups of people.

Ultimately, understanding exactly how our spines and muscles adapt (or don’t adapt!) during common tasks like pushing and pulling, especially when chronic pain is in the picture, is super important for giving better advice on how to move safely and prevent future flare-ups. This study is a solid step in figuring out some of those secrets!

Source: Springer