Is Lifting With a Rounded Back Really Bad?

"Keep your back straight."

"Bend your knees, not your back."

Most of us have heard these cues countless times—whether at the gym, at work, or even while helping someone move furniture. As a result, many people believe that bending or rounding the spine while lifting is inherently dangerous.

But does the evidence support this belief?

The fear of spinal flexion

Many people become worried the moment they see their back round during a squat or deadlift. This fear isn't limited to people with back pain either. Research has shown that beliefs about bending the spine can contribute to fear-avoidance behaviours, even in people who are pain-free (Knechtle et al., 2021).

While it's understandable to want to protect your back, modern research suggests that the relationship between spinal position and injury is far more complex than simply "rounded equals bad."

Does spinal flexion cause back pain?

A systematic review and meta-analysis by Saraceni et al. (2020) found no convincing evidence that spinal flexion during lifting increases the risk of low back pain or injury.

This doesn't mean spinal position is irrelevant—it means that spinal flexion, by itself, does not appear to be a reliable predictor of injury.

A perfectly straight back isn't realistic

Another common misconception is that we should always maintain a perfectly neutral spine when lifting.

In reality, studies have shown that some spinal movement is normal and unavoidable, even during well-executed lifting tasks.

Research has demonstrated that people naturally move through varying amounts of lumbar flexion during common exercises, including:

• Squats

• Deadlifts

• Kettlebell swings

• Good mornings

In other words, the spine is designed to move. Trying to eliminate every degree of spinal flexion simply isn't realistic.

So why do some people hurt their back?

Like most tissues in the body, the spine responds to load.

Problems are more likely to occur when the demands placed on the body exceed its current capacity—not simply because the spine moved into flexion.

Think about someone who has never bench pressed before deciding to perform 100 repetitions at 60 kg. If they wake up with sore shoulders or chest muscles the next day, we wouldn't conclude that the bench press itself is dangerous. More likely, they simply did too much, too soon.

The same principle applies to the spine.

Your body adapts to what you train

One of the key principles of rehabilitation and strength training is progressive overload.

Over time, your muscles, tendons, bones and connective tissues adapt to the loads and positions they are regularly exposed to.

A good example is the Jefferson curl—an exercise that intentionally trains the spine through loaded flexion. For someone who has never performed the movement, jumping straight into heavy Jefferson curls wouldn't be advisable. However, when introduced gradually and progressed appropriately, many people can build strength and confidence in these positions.

The goal isn't to avoid spinal flexion forever—it's to build tolerance to it over time when it's relevant to your activities or sport.

What about "butt wink"?

Many lifters worry when they notice their pelvis tuck underneath them at the bottom of a squat, commonly referred to as a "butt wink."

Some degree of pelvic movement and spinal flexion is common and often unavoidable due to differences in anatomy, mobility and squat depth.

Rather than trying to eliminate every bit of movement, it is often more helpful to ask:

• Is the movement comfortable?

• Is it repeatable?

• Is the load appropriate for the person's current capacity?

These questions are usually more clinically meaningful than chasing a perfectly neutral spine.

The bottom line

The current evidence does not support the idea that lifting with a rounded back is inherently dangerous.

Instead, injury risk is likely influenced by many factors, including training history, load, recovery, fatigue, overall health and how quickly training demands increase.

Your spine is a resilient structure that is designed to move—including into flexion.

As with any exercise, the key is respecting your current capacity and progressing gradually over time. Rather than fearing certain positions, focus on building strength, confidence and tolerance to the movements that matter most for your daily life, work or sport.

References

• Aasa et al. (2019) PMID: 31718474

• Edington et al. (2018) PMID: 30200300

• Knechtle et al. (2021) PMID: 33323888

• Saraceni et al. (2020) PMID: 31775556