Squatting in running shoes isn’t ideal, but it’s unlikely to cause injury at moderate weights. The main issue is stability: running shoes have thick, compressible foam designed to absorb impact, and that same cushioning creates a soft, shifting surface underfoot when you’re trying to push heavy weight through the floor. Whether that actually matters depends on how much you’re squatting and how seriously you train.
Why Running Shoes Feel Unstable Under Load
Running shoes are built to cushion repetitive impact. Their midsoles use layers of foam, sometimes with air or gel pockets, that compress and spring back with each stride. That’s great for absorbing the shock of running, but it works against you during a squat. When you load a barbell on your back, you need a firm connection to the ground. Compressible foam between your foot and the floor acts like standing on a mattress: your body has to recruit extra effort just to stay balanced, and force that should travel straight down into the floor gets absorbed or redirected.
Most running shoes also have a heel-to-toe drop of 8 to 12 millimeters, meaning the heel sits noticeably higher than the forefoot. This forward pitch shifts your weight distribution and can change how your torso leans during a squat. For some people that actually helps squat depth (weightlifting shoes use a raised heel on purpose), but the key difference is that a weightlifting shoe’s heel is made of hard, incompressible material. A running shoe’s heel is soft foam that compresses unevenly under heavy load.
What the Research Actually Shows
Here’s where things get nuanced. A study published through the International Journal of Exercise Science compared barbell back squats performed barefoot versus in running shoes and found no significant differences in knee joint range of motion or knee joint forces between the two conditions. In other words, at the loads tested, wearing running shoes didn’t measurably change squat mechanics or stress on the knees compared to squatting with no shoes at all.
That doesn’t mean the concerns about stability are overblown. It likely means that for lighter to moderate loads, your body compensates well enough that the differences don’t show up in joint measurements. The story could be very different at heavier weights, where small balance shifts become harder to correct and the margin for error shrinks. If you’re squatting under 135 pounds as part of a general fitness routine, running shoes are probably fine. If you’re working toward heavy singles or doubles, the instability becomes a real limitation.
When It Actually Becomes a Problem
The practical risks of squatting in running shoes increase with weight and fatigue. At heavier loads, the foam compresses more, and it doesn’t compress evenly. If one side of the sole gives way slightly more than the other, your ankle can roll inward or outward mid-rep. This is most likely to happen during the bottom of a deep squat, where your balance is already at its most precarious. You might not get hurt, but you’ll likely feel less confident and controlled, which limits how much weight you can safely progress to.
Fatigue compounds the issue. During the last reps of a tough set, when your stabilizing muscles are already tired, a squishy sole gives your body one more variable to manage. Some lifters describe the feeling as “squishing” or “sinking” at the bottom of the rep, and it can throw off your bar path enough to turn a good rep into a grind.
Better Options for Squatting
Flat-soled shoes like Converse Chuck Taylors or Vans are a popular and inexpensive alternative. Their thin, firm rubber soles keep your feet close to the ground and distribute weight evenly across the heel and midfoot. Without thick foam doing the stabilizing work, your feet, ankles, and calves engage more actively during the lift, which builds proprioception (your body’s sense of position and balance) over time. Vans in particular offer a wider toe box, which gives your toes room to spread and grip the floor.
Dedicated weightlifting shoes are another option if you squat frequently or compete. These have a hard, elevated heel (typically wood or dense thermoplastic) that helps with ankle mobility and upright torso position without the instability of foam. They’re overkill for casual gym-goers but a real upgrade for anyone squatting multiple times per week.
Going barefoot or in socks is also a legitimate choice in gyms that allow it. You get the flattest, most stable surface possible, and full sensory feedback from the floor. The trade-off is less foot protection if you drop something, and some commercial gyms prohibit it for hygiene reasons.
The Bottom Line on Your Running Shoes
If running shoes are all you have and you’re doing bodyweight squats or moderate-weight goblet squats, they’re not going to hurt you. The research shows no meaningful change in knee mechanics at typical training loads. But if you’re progressing into heavier barbell work, the soft, unstable sole becomes a limiting factor for both performance and confidence under the bar. Swapping to a pair of flat-soled canvas shoes costs $40 to $60 and makes an immediate, noticeable difference in how solid you feel at the bottom of a squat.