Getting stricter on your technique is good for the long run, but for now is actually a "progression". Its going to take time to adapt to the better form. Work through it. Going deeper is definitely harder, but so worth it. So just realize you have not "stalled", you progressed to a more difficult variety of squat.

There's not really enough info here to know exactly what's going on, but if your concern is strength, you are probably doing too many moderate to high rep sets. Generally you won't increase absolute strength with higher rep ranges. Most people get better muscle growth with longer tension times, but not much 1RM benefit. You might get better results by doing more sets with heavier weights and fewer repetitions (5 X 5; 10 X 3; etc.). Strength in squatting is a skill you have to develop, just like playing a musical instrument, hitting a baseball, etc. You have to practice with heavy weights if you want to get stronger. You also might be overtrained, as a previous commenter mentioned. A layoff might be needed to allow your nervous system to recuperate and adapt.

General advice I hear and that's worked for me is, if you're having trouble progressing, deload to 70% and continue as before, usually you'll break through the weight of the plateau next time you hit it. If that doesn't help, you might need to reconsider your program; e.g., if you're doing a 5x5, you might switch to a lower-volume program like a 3x5.

Depends. There's a lot of stuff that could go on. As for sprinting, I'm not sure. I know that kb swings have helped my endurance level. (at this point, I'm going for pure strength, so no sprints or other stuff till I add more muscle).

Here's a couple thoughts though...

Do you have a deload week? You might want to take a look at your training. If you've been working 6-8 months at this, it's time to drop the weight a bit, and give yourself a bit of a break, or just a week off, and then start at a lower weight.

You're saying the third set. Of how many sets? How many reps? I get really good mileage out of 3x5 (starting strength), but please remember, squats are uncomfortable, not necessarily fun, and you have to keep your head in the game. A lot of this is mental! (of course, there's also 5x3x1, 5x5, etc).

Is this trainer someone who has powerlifted or knows how to squat? You might look at getting professional instruction by a powerlifting coach...or watch the elitefts "how to squat" series on youtube if you want to check your form to be sure you're doing it good. A lot of being able to squat well is all on technique.

You talk about mobility. Have you done mobility WOD "the first of many beatdowns"? It's a 10 minute squat hold and really works on your flexibility. http://www.mobilitywod.com/2010/08/first-of-many-beat-downs.html

edit how long are your rest periods? I grab a bench and sit down for a good 3-5 minutes between each set. I wasn't so sure of this in the beginning, but reading starting strength and t-nation has really sold me on how important rest periods are.

If anything I think you should rest and cut back while your muscle is damaging/growing in reaction to deeper squats. I would add the sprints later if you want or maybe some lunges and deadlifts ( you are probably already doing those.) If you're losing steam maybe you need to add some carbs post-workout like sweet potato.

If your form is changing, especially if you're going deeper on squats, then comparing your weekly lifting numbers isn't necessarily an accurate measure of your progress. You're comparing apples to oranges. Focus on proper form, then once you have proper form you can start comparing your lift numbers for an accurate measure of your progress because your form will be the same every time.

If you don't think that's the issue, then perhaps try heavy singles for a few weeks. I did a 5x5 for about 6 months, then I plateaued. To get past it I did 7-8 heavy singles for each of the main lifts for 4 weeks. My Bench went from 245* -> 275, my Deadlift went from 325* -> 375, and my Squat went from 285* -> 315 (I don't squat much). I put the asterisks there because my starting maxes were theoretical 1RM based upon my best 5RM during my 5x5, so there's some room for error. This week I am talking a week off and then next week I will return to doing a 5x5 like before, so then I'll be able to compare apples to apples, but I think it's safe to assume I will be noticeably stronger. If 5x5 is the heaviest you've done in last 8 months, then you would probably benefit from heavy singles too.

You're doing too many reps for optimal strength gains. Try 3x5 or 5x5. The latter is the Stronglifts method, the former is the Starting Strength method. They're very similar programs, so you can start with either. The fundamental concept is squatting three times per week, and on alternating days, switch between two additional exercises (bench, deadlift, overhead press, and the power clean or barbell rows. You don't do any other exercises during these three lifting days.

Your trainer will likely not approve, because most trainers do these exercises wrong, and since the program isn't complicated, the need for a trainer once you get your form down quickly dwindles anyway.

If you don't want to switch to Stronglifts, Starting Strength, or similar program, and you're purely looking to gain progress on squats, I'd still recommend doing a 3x5 or 5x5 routine for the squat and deadlift, since they're complimentary exercises.

Seconding that 10 reps is way too much for strength. There are some studies linked from the strong lifts blog. Also, you should make sure that you rest enough between sets, could be you need 2 minutes. Possible you need 5 (five!) minutes.

One thing that has helped me with plateus, is to take a much higher weight, do a couple of reps, maybe just a quarter squat, rest and try my working weight and it becomes much easier. This is a known effect, but the name escapes me.

Neil, I believe that sprinting is a fantastic exercise to add to your routine. I would recommend reading Mark Sisson's "Primal Fitness" eBook, which you can get by signing up for his newsletter at marksdailyapple.com. He concentrates on body weight exercises (including the squat), which may be perfect for you to back off into.

It may be worth your time to follow Mark's body weight exercises and get to the standard level for that before going back to adding weights. You'll find that you'll receive a more "holistic" muscle development, which will help prevent you from hitting gain "walls" where certain muscles require a bit more attention in order to add more weight effectively.

Check out the mic'd instructor on again faster (http://www.againfaster.com/) and search for fixing your squat. Provides a number of good exercises to improve form - increased depth and . upright chest