I've been working on performing squats to failure. I tried 175 last night, I got to 12 reps but the last rep my form failed. Is this failure? or do I just need to work on form? Did my form fail cause my legs failed or was my form fatigued? It felt like (on the last rep) that i was using my back to get the weight up. Or is failure when i can no longer rise up from the bottom position? I'm trying to find a weight that i will fail at 10-12 reps. btw i just switched back to doing back squats from front squats.
Your legs/hips failed in the movement and you were using your lower back to aid in completion. A lot of people will tell you that this is very dangerous, I will not be among them. I do the same thing near the end of my sets. Concentric failure is when you can no longer complete a rep, so if that was the case, you went to failure. You did just fine. For your next session, up the resistance to 185 and get as many reps as possible. Once you are able to get this for 12 reps, up the resistance again.
hey pete o to add to what chris said, i noticed when i first started to do squats my main problem was that my back would fail before my legs. My legs have always been big. What happened was that my legs would continue to drive and straighten whilst my back remained bent over. However, now after performing them for some time now this is no longer the case. I fail near the typical sticking point which is down towards the bottom of the movement.
Since you have switched from front squats this may be applicable