A New Trick for Building Your Legs

1. This setup is much more unstable due to the lack of rigidity in the handles/straps. You're forced to use very strict mechanics and dial-in form; otherwise the barbell will tilt to one side or slide off. If you have a tendency to favor one side or allow one hip or shoulder to dip, this setup will give you immediate feedback via a teeter-totter effect. Most lifters will immediately feel their abs and core working overtime.
2. This is the most effective barbell variation I've used for teaching lifters how to pull the bar into their backs, which is a critical component for any barbell squat. It helps create increased spinal rigidity, enhanced lat activation, and a more stable bar position. With this variation, if you don't pull aggressively on the straps and pull the bar into your back, the bar will literally fall off.
3. The makeshift safety squat bar setup reinforces the hugely important hip hinge. It requires you to keep your hips set almost all the way back to create a slight forward torso lean in order to keep the bar from sliding. If you get into an overly upright position, pull the head up via cervical hyperextension, let your hips shift forward, or allow anterior knee drift, the bar will roll off.
4. This is great for teaching rigid spinal mechanics. Although the arms are pulling forcefully against the straps to keep the weight anchored onto the traps, even the slightest loss of spinal rigidity or proper postural alignment will cause the bar to tilt. Also, spinal flexion caused by using excessive depth and exaggerated range of motion is similarly punished.
5. Similar to a standard safety squat bar, this strap version is much more conducive to promoting proper lower-body squat mechanics, mainly because the t-spine and shoulder mobility aren't an issue. When the shoulders and scapula elevate or protract (a common problem on normal squats), it impacts t-spine positioning, ultimately resulting in faulty spinal alignment throughout the entire vertebral column. Besides making the squat more dangerous, it also makes it nearly impossible to optimally target the lower body.
6. This setup is particularly useful when doing partial squats in the bottom half of the movement.

It keeps you locked into a very precise and rigid position that not only keeps the bar locked onto the upper traps, but causes a degree of constant tension strong enough to trigger growth in even the most stubborn legs.

This same setup can also be used for good mornings as demonstrated here by NFL defensive tackle, Lawrence Virgil. Many of my larger athletes prefer this setup because it doesn't require the same degree of shoulder mobility and flexibility as standard good mornings do.

Many lifters are unable to keep their shoulders retracted and depressed when doing good mornings, which not only makes them ineffective for taxing the posterior chain, but also makes them trickier on the spine, shoulders, and neck. But the neutral shoulder position reinforced by the makeshift safety squat bar eliminates this issue.

As a result, they're much more effective in keeping ideal spinal positioning and postural alignment, not to mention being highly effective for crushing the glutes, hamstrings, and spinal erectors.

This is also great for lunges, split squats, and Bulgarian squats because it reinforces the hip hinge. You have to keep your hips set back almost maximally throughout to create a slight forward torso lean. In other words, it promotes ideal lunging and split squat mechanics.

It also forces you to stay in the bottom three-fourths of the movement because locking out or coming up too high at the top of the lunge will cause the torso to become overly upright, resulting in bar slippage. The amount of constant tension is incredibly high, making it very effective for spurring gains in functional strength and hypertrophy. Just be prepared for a serious burn.