When we go to the gym, whether it’s for yoga, Zumba, or weight lifting, we’re surrounded by mirrors, and that’s especially true when we’re doing squats. In weight rooms, the mirrors are perfectly aligned with squat racks to give visual feedback on form and positioning, but do they hurt more than help us during squats?

A recent study presented at the Association of Academic Physiatrists (AAP) Annual Meeting in Sacramento, Calif., found performing squats in front of a mirror has no effect on our ability to distribute weight evenly when we squat. Moreover, mirror use during squats can distort our visual and sensory perception of where our body is and how it feels.

"The goal of most people who perform double leg squats as part of their exercise routine is to make sure their weight is evenly distributed on each leg. Everyone tries to achieve symmetry because they want to work out each leg equally during the squat,” said Dr. Monica Rho, director of Women's Sports Medicine at the Rehabilitation Institute of Chicago's Sports and Spine Rehabilitation Center and assistant professor at Northwestern University's Feinberg School of Medicine, in a press release.

In an effort to observe whether a mirror helps people do symmetrical squats, Rho and her colleagues recruited five healthy males and five healthy females between the ages of 18 and 50 without a history of skeletal or balance problems.

The participants performed a series of double-legged squat exercises using both legs to squat to the fixed height of a chair in three different foot positions, and a series of deep squats, which involves dropping the hip crease all the way past the knees, both with and without a mirror. Foot positions included: Five squats in a fixed position with the feet forward at a set distance; five squats in a mixed position with the feet at a fixed distance but in a self-selected position; and five squats in a self-selected position with the feet at a self-selected distance and position. The participants performed the squats at their own pace.

The researchers asked the participants to stand with their feet on two different force plates to calculate the amount of force, known as the preferential load shift, put on each leg during the exercises. They also observed maximum knee and hip flexion angles during deep squats.

When the participants stood in the fixed position in front of a mirror, they favored their dominant legs, shifting an extra 0.56 percent of their weight to that side. When they were asked to do the same squat without the mirror, they put an extra 1 percent of their body weight on their dominant side. Although there was a difference between squatting with or without a mirror, it was so small the researchers did not consider it statistically significant.

When the participants were allowed to choose their own starting foot positions, they tended to shift 0.82 percent of their body weight towards their non-dominant leg with a mirror and 0.74 percent without a mirror. Similar to the initial findings, this was not a statistically significant difference. The researchers concluded the presence or absence of a mirror did not seem to alter the person's ability to distribute their weight evenly during a squat.

"Our findings indicate that, when it comes to equal weight distribution and symmetry of loading each leg during a squat, the mirror doesn't seem to make a difference," said Rho.

Rho and her colleagues want to pursue further research and suggests it would be beneficial to test a larger population to see if the use of a mirror would “affect the ideal squatting form of the knees remaining over the ankles not in front of them during the exercise.”

Relying on a mirror for form and performance will only give limited feedback. A mirror provides the least information about our body and position because it only focuses on the frontal plane, which divides the body into front and back. It’s also difficult to assess depth and the relationship between the kneecaps and hips from this perspective.

Mirrors can also affect our sensory input because we begin to focus on how the body looks when it lifts, rather than paying attention to how it feels. And it can create delays in our reaction time by forcing us to interpret what we see before correcting a balance problem.

Tim Henriques, a writer for TNation, suggests doing the following test to see if you rely primarily on vision for balance: “Stand on one foot and maintain balance for about 15 seconds. When you’re relaxed and comfortable in that position, close your eyes and see how long you can go,” he writes. “If you fall over within a second or two of closing your eyes, you're likely relying on vision for balance.”

Source: Rho M et al. "Using a mirror for squat exercises: Is there a benefit?"Association of Academic Physiatrists (AAP) Annual Meeting in Sacramento, Calif. 2016.