Try using the Safety Bar for rear-foot elevated split squats. The Hatfield variation, where you hold spotter arms or hand supports, gives you the ability to use more weight and gain more control over the eccentric.
You can bias the quads a bit more by dropping the rear foot down and adding a wedge or heel ramps to the lead leg to maximize knee flexion.
The spotter arms will also assist you during the concentric portion of the movement, especially if your intent is to overload the eccentric or isometric components. Having something to hold onto will let you use more weight than a barbell split squat would allow, increasing tension on the muscles.
Bonus: The hand-assistance will also take pressure off your back.
- Start with a Safety Bar, rack, and bench to elevate your back foot. Step the foot under the pins. You need to be close enough to hold the rack but not hit the pins with the bar on the way up.
- Set the back foot on the bench, laces down.
- Get your grip about 6-12 inches below the pins. Too high and your arms interfere with the bar path. Use your hands for stability but don’t pull up.
- Use a slight forward lean to prevent the bar from falling off your shoulders. Maintain a vertical shin angle as you descend into the squat while pushing your working hip back.
- Keep your torso straight and keep a vertical shin to make this easier on your knees.