You want more impressive ups? A good sports supplement can help, but you will also need to work on explosive movements, as well as strengthening your glutes, calves, and the muscles around your hips. Still, all of that is secondary to establishing your jump form.
Just like running, bench pressing, or throwing a football, your mechanics and form will determine just how well you execute the movement. If you can’t find a strength coach or certified personal trainer to critique your jumping form, record yourself doing a half a dozen jumps and then make your assessment. Be a harsh critic and determine what you can tweak to include or engage more muscles per jump.
In terms of exercise, start with body-weight jump squats. They’re a great way to establish a solid jumping form as you build the muscles in your legs. Begin with three sets of 12-15 reps. As that set/rep scheme becomes easy to accomplish, add things like resistance bands, a weight vest, or ankle weights to make the movement more challenging.
Box squats are another exercise that can help you build both strength and explosiveness to improve your vertical leap. Slip a box underneath your butt as you perform a traditional back squat. Descend until your butt hits the box, sit for a beat, and then explode up as quickly as possible finish off the movement.
Mix other squat variations, like the front squat, Zercher squat, partial squat, and hack squat, into your routine to create new sets of demands on your muscles. Include heavy resistance exercises like the leg press and glute-ham raise to cap off your legs training session.