YOU NEED TO PRACTICE SINGLE LEG WORK!!
As a surfer, you need to be working on stability, strength, power, balance, and proprioception, all on a single leg! Squats are great, but think for a minute about your legs on a surfboard. They are in constant motion, dynamically involved in all the previously mentioned qualities, all while working largely independently of each other. I could go on with why this is so crucial, the positive effect on glute max and medius recruitment, the stability and mobility required at the ankle complex, but BOTTOM LINE- USE THIS EXERCISE!! Single leg work is an ABSOLUTE MUST in knee injury prevention. In the video, I demonstrate a beginner version (low box), and a more advanced weighted version. Form is critical when working on step ups, to not only ensure proper muscle activation, but to also save your knees. The force needs to be applied through a strong foot, with emphasis through the heel (this is an attempt to prevent quad-dominance, which can stress knees). Squeeze your glute, then drive yourself upward. Do not allow the knee to move excessively laterally. If this occurs, lower the weight, or box height. Also, pay attention in the video to the side profile shots. Watch my knee, see how it doesn’t move way out over my toes? Mimic that! Start utilizing step ups, with rep ranges of 10-14, but perform them perfectly, and occasionally work on them in your bare feet… as this will help strengthen all those little foot muscles…. which is great for board control.