Anyone buying a barbell and rack for home has to decide how to squat: bar high on the shoulders or lower across the back, feet narrow or wide, shallow or deep. Advice online often assigns each choice to a muscle. This article summarises the abstracts of two 2026 studies that recorded muscle activity during the back squat and states what they can and cannot support. Both are small experiments in healthy adults measuring electrical activity, not muscle growth or strength gains over time. It is general information about training, not medical advice.
Study one: 18 people, four technique variables
Lee, Crossman and Kedgley, in PLOS ONE (2026), recorded surface electromyography (EMG) and movement data from 18 healthy participants, 12 men and 6 women. They compared a high-bar with a low-bar position, a wide with a narrow stance, and two loads: a light set of ten repetitions at 50% of maximum and a heavy set of three repetitions at 80%. Seven muscles were measured across the thigh, hamstring, calf and glute regions.
A wide stance increased both peak and total activation of the vastus medialis, one of the quadriceps muscles. A heavier load increased total activation of the vastus lateralis and the semitendinosus, a hamstring muscle. Peak activation of the biceps femoris, another hamstring, was higher when a high bar and wide stance were combined with the heavy load than with the light load. Movement differences were modest: a narrow stance produced 3.7 degrees more peak knee flexion and 8.2 degrees less hip abduction, and a low bar produced 3.4 degrees more hip flexion.
The authors concluded that consistent muscle activation did not favour any combination of stance, bar position and load. Lifters wanting to build strength can choose among several combinations, guided by comfort.
Study two: 22 experienced men and three depths
Park and colleagues, in Medicina (2026), tested 22 adult men with at least two years of back-squat experience. Each performed high-bar and low-bar squats to knee-flexion angles of 50, 90 and 130 degrees, using a load equal to 80% of the man’s usual one-repetition maximum, in randomised order. EMG was recorded from the quadriceps, glutes, hamstrings, abdominal wall and lower back, and analysed separately for the lowering and lifting phases.
Squatting deeper most consistently increased activation of the quadriceps and the erector spinae, the muscles running along the spine. Gluteus maximus activation changed only a little with depth. Bar position produced selective effects that depended on depth and phase: the low bar showed greater hamstring and erector spinae activation in specific comparisons, while the high bar showed greater knee-extensor activation at selected depths, most clearly in the rectus femoris. The authors concluded that bar position and depth adjust relative demand on the knee extensors, trunk stabilisers and back of the leg, rather than targeting one muscle alone.
What the two studies agree on
- Effects are shifts in emphasis. Neither study found that a technique switches one muscle on and another off.
- Depth and load matter. Both found that changing how deep or how heavy the squat is altered activation, in some cases more than bar position did.
- Some differences were isolated. Many of the reported bar-position differences were confined to particular muscles, depths or phases of the lift.
What the studies cannot show
Electrical activity recorded at the skin is an indirect measure of how hard a muscle is working. Higher activity in a session is not the same thing as more muscle or strength after weeks of training, and neither study followed lifters over time. The first study had a small mixed sample, and the second tested only men who were already experienced, so neither can be assumed to describe beginners, older adults or women. Neither compared injury rates, so no conclusion about which position is safer can be drawn from them.
Because the studies tested different loads, depths and muscles, they cannot be pooled into a single ranking. The site’s summary of hip thrust and back squat evidence for glutes shows how much further apart short EMG results and longer training trials can sit.
What this means when choosing equipment
The bar position decision does not change what needs to be bought. Either variation uses the same barbell and rack, and the equipment questions are about the rack’s uprights, hook or safety-arm height and whether a bar can be racked and unracked comfortably at a chosen depth. The comparison of power racks, squat stands and half racks covers those differences, and the note on steel gauge and upright dimensions covers the build.
A practical reading of the research is to pick the variation that feels stable and repeatable for a given body, keep depth consistent from session to session so progress can be tracked, and treat any muscle-emphasis claim as modest.
Frequently asked questions
Does a low-bar squat work the hamstrings more? In the 22-man study the low bar showed greater hamstring activation in specific comparisons, not across every depth, so the effect was selective.
Does a wide stance work the inner thigh muscle more? In the 18-person study a wide stance increased activation of the vastus medialis, a quadriceps muscle on the inner thigh.
Is a deeper squat better for the glutes? In the 22-man study gluteus maximus activation changed only a little with depth, while quadriceps and lower-back activation rose more consistently.
Is there a best squat technique? The first study concluded that no combination was consistently favoured and that comfort can guide the choice.
The bottom line
Two 2026 experiments found that bar position, stance width, depth and load change which muscles work hardest in the back squat, but only modestly and often in isolated comparisons. Neither measured muscle growth, strength over time or injury, so neither can rank the techniques. Choosing a stable, repeatable squat that suits the lifter, with a rack set up to match, is better supported than choosing a technique to target a single muscle.
Sources
- Lee CXY, Crossman AJ, Kedgley AE, “The effects of bar positioning, stance width, repetition, and load on muscle activity during the barbell back squat,” PLOS ONE, 2026
- Park JH et al., “Effects of Barbell Position and Squat Depth on Trunk and Lower-Extremity Muscle Activation During the Back Squat in Healthy Adult Men,” Medicina, 2026