Today I'm going to talk about how to hit the ball harder on your backhand. This is an area that limits mot players. I have some simple techniques to help you generate more pace. I have separated this topic into 6 subcategories for easier reference.
The Swing: 1) Racquet Prep/Torque: There are a lot of important points on the backhand swing. The first for me is getting the racquet prepared early enough so you can move forward (toward the front wall) to contact the ball. The backswing needs to have more than just your racquet prepared, you also need to rotate your shoulder so you have your power set and a lot of torque in your body. Most people don't have enough torque or do this too late. To improve your torque, try focusing on dipping and rotating inwards your leading shoulder. SquashSkills describes this nicely with good pictures here http://squashskills.com/blog/31/2005-the-backhand-diamond. While creating this torque in your swing it is important to keep your head still. If you are not flexible enough you will have to work on this. I like to think of my backhand swing as leaning into my shot, because most of my power comes from this torque and shoulder/core rotation. 2) The Downswing/Contact Point: Your forearm and wrist extension is important in your backhand swing. This gives you that extra 'snap' as your racquet heads catches up to your swing. You can hear this and how your swing velocity increases just by taking some practice swings without hitting the ball. Do this and listen for the swish sound your strings make. Finally, on the 3) Follow Through: even though this is after you've made contact I feel it is important to have a full follow through and to finish with your elbow extended and your racquet pointing towards your target. If you have an abbreviated follow through this means you will not have contacted the ball with maximal force. A full follow through as an added benefit as well as its momentum helps you clear towards the middle of the court. I should also mentioned here to be careful, you don't want to have a dangerous and excessive follow through.
Footwork/Approach: it doesn't matter how good your swing is if you don't have proper footwork. Most people have an easier time moving forwards and hitting with pace. And although I can hit comfortably on an open stance on my backhand I cannot generate nearly as much power on my backhand, so if I want to be attacking on this shot I try and hit off my front foot (closed stance and for righties your right foot) whenever possible. Here is a footwork tip moving to the front of the court. If you are approaching the ball but it is a foot or two further in front of you and this means you will end up hitting off of your back leg, instead try practicing a hop/skip on your left leg so you can get further up the court and hit off of your front foot. Moving backwards is a little more challenging. When doing this I want to get behind the ball so I can step forwards (towards the front wall) so I can get more power. This also allows me to hit crosscourt if I like. Moving from the T to the back corner I push off of my right leg, so my first step is with my left foot towards the corner, my second step is with my right foot and it goes slightly behind my first step. My third step I try and get back and behind the ball so I can then step forwards and lean into my shot with my fourth and final step (on my front foot/hitting closed stance). I like to think of good footwork as the key to putting the squash ball on the tee..for example, sports like golf or tee ball, you want to hit off of a tee from a specific distance away from the ball, this is the same in squash, but we need to move very quickly to get into this correct spacing to put the squash ball on our invisible tee. If you can do this consistently you will hit the ball harder and more accurate.
Balance/Spacing: here it is important to give yourself adequate amount of space between yourself and the ball. If you get too close you will have a restricted swing and if you're too far away you cannot step/lean into your shot. A proper base of support has much to do with your footwork and how you approach the ball. You need to be stepping forwards with your front leg which is an abduction motion of your hip joint to get maximum amount of power (as opposed to just stepping beside you). Many people don't get low enough. Make sure you get your hips down and bend your front knee so you can really lean into and transfer your weight onto the ball. The taller you are the lower you have to get. Even just getting a couple of inches lower will make a big difference. Get to the height of the ball you are striking and this will also allow you to stay a little further from the ball.
Off Court Training/Gym Exercises: I believe that doing rotational core exercises are important here. There are a number of good ones you can do without any equipment and others you can do with medicine balls. When doing these core exercises, try to think about focusing on the plane that your swing is on. You can also use the heavy duty plastic bands/tubing and tie it to something and take some backhand swings. With the tubing you will only have the resistance in one direction (the backswing or downswing/follow through). I believe the downswing, contact point and follow through is where you should have the resistance, which means having the tubing tied up behind you (if you're a righty then behind your left shoulder) to a door or a sturdy piece of equipment.
Squash Drills/Routines: for practicing hitting the ball with more pace one needs to have someone feed or use a ball machine. While doing this make sure the ball is fed nicely in front of you so you can step forward and lean into your backhand drive. You can also try doing some sidewall to sidewall drives. In this exercise you are hitting by yourself and you hit a forehand into one of the sidewalls which hits off the other sidewall, next you hit your backhand into the sidewall and back to the other. Here you alternate hitting forehand drives and backhand drives and you can hear the pace you are striking the ball with. After these drills I would then move up to boast drive and some drive drive drop, drive drive boast, and see if the person driving from the front can play more attacking and powerful drives from the front corner especially. You can also put down a target such as a cup or a shoe. Because although you are trying to get more power, an attacking drive is also about the placement of the shot not just how hard it is struck. Finally, here is a good fun game. You play a normal game but you try and strike every shot as hard as you can. Obviously sometimes you are not balanced and don't have time, so in these situations as hard as you can may not be very hard. And yes, this also includes your serves. Of course you will have to call your lets and be careful about giving your opponent space and calling your lets when you feel like you are being crowded. It is a fun game and you learn a lot about how to prepare and approach the ball to hit it with more pace.
How to Hit it Even Harder: I would only advise high open level players to attempt this or else you could endanger your opponent with this larger swing. And if you can't hit a regular backhand well, maybe wait until you get that sorted out first. When I want to hit the ball with as much more force as I can I actually flatten out my swing and hit the ball with a closed racquet faced and even with a slight topspin. I do this by starting my backswing starting much lower, no longer over my shoulder anymore, I'd say more around mid-torso (but I still produce a lot of torque) and I finish my swing at shoulder height or even just above, so the plane of my swing is no longer flat, it's low to high (but not as much as tennis!). I figured out how to do this while solo hitting and only do it when I'm feeling really confident on court. Even though my opponent can clearly see that I'm setting up slightly different I can produce a lot of power and most people struggle moving into the backhand under pressure. If I was still working on my own game I would continue developing this shot and try and couple this set up with other shots (like a boast and low hard crosscourt drive) to make it harder to read. I attempt this from the front once in a while (but it takes longer to clear and your opponent can tell you are not going to drop), but mostly hit this shot from the back corner when I have lots of time to prepare. I feel this type of swing gives allows my swing to have a full arc and larger radius and this is how I can hit the ball hardest..most accurate, well probably not..but this post is about maximum force production!
So these are my tips for hitting with more pace on the backhand. You need time and space to be able to do this. If you don't have one or both of these than it's the wrong situation to try and hit the ball so hard. I would always pick control over power, but having both is much better!