Everyone wants the perfect workout: tight, compact technique that builds strength and burns calories in the simplest ways.

One solution is personal trainers, but that costs money that not everyone has. Another is watching online videos, but that can leave gaps in the routine and lead to other issues.

Stack.com recently offered these simple tips from Mike Boyle, co-founder of Mike Boyle Strength and Conditioning, to fix four common exercises most high school and college athletes use. Check them out:

Squat

A common – and dangerous – squat mistake is when the knees cave inward. This puts stress on the knees and can be a precursor to an ACL injury. Also, if it occurs during a squat, it’s also can happen during more dynamic moves in your sport, such as change of direction or landing from a jump.

Fix: Wrap a mini-band around your thighs just above your knees. Your abductors must activate to keep your knees in line with your hips and ankles, strengthening the muscles and programming the movement.

Single-leg squat

The single-leg squat is a more challenging version of the squat, so the knee is less stable and more likely to cave in.

Fix: Since you cannot wrap a band around your other knee, you need a partner to pull your knee inward. This is challenging, but it eventually teaches you use your glutes to stabilize your knee and keep it properly aligned.

Overhead lifts

For individuals with poor core strength or mobility, the lower back may arch, causing back pain among other issues.

Fix:  Overhead dumbbell carries put you in a position where if you don’t engage your core and keep your body organized, you will slip into a bad position. Focusing on maintaining an upright posture challenges the core muscles, fires the glutes and forces you to keep a neutral spine.

Push-ups or bench press

If your elbows flare out early when you perform a push-up or bench press, you put stress on your shoulders that can cause an injury, and you won’t be in a good position to engage the back, limiting strength in these movements.

Fix: Wrap a resistance band around your wrists and imagining driving the band outward. This activates the back muscles and keeps the elbows closer to a 45-degree angle with the body.