Numb legs or a nerve pain up the leg is common in surf ski paddling. The sciatic nerve runs from our lower back all the way down to our feet and if we are sitting in a fixed position for a period of time we are placing stress on this nerve and could aggravate or inflame it.
To avoid this, we need to have more flexibility particularly in our hamstrings, calves and glutes. You also need to look at how you sit in the surf ski, if you sit more upright and improve your posture you will take the stress off the sciatic nerve. Also look at your leg length, if your foot plate is too close to you then you are jammed in the seated position and could be placing the hamstrings and sciatic nerve under too much stress.
Also look at your leg drive and make sure you are pulling from the hip and rotating your torso, which places the load through the torso muscles and allows the hamstrings and sciatic nerve to have less stress placed upon them.
The combination of all these factors – flexibility, posture, leg length and torso rotation can be the solution to avoiding numb legs and sciatic nerve pain.