I'm tall, 6' 5" and if I walk around all day I get an ache in my lower back other than that my lower back is fine. I've just finished reading the chapter on lower back pain from Science and Practice of Strength Training "Zatsiorsky & Kraemer". The bit where they describe the pain receding when raising your knees was the perfect description of my pain when I have it so I'm pretty sure my core is as weak as water. I highly recommend this book, I seen it recommended by several individuals here so I got it, worth every penny. So I need to start working on my core. I've been looking at core strength exercises that I could do and there are plenty. I have a barbell and various plates with no bench or rack. I have a large garden, 60' long x 30' wide (that's large where I live). The discs have grips so side bends are quite easy and I have 25kg plates to do these with. Would the farmers walk work my core that well. When I do it with the two 25kg plates I typically feel it on the shoulders, arms and grip but after a fair distance. I've had a look on Ross's site and I like the idea of hammering the shit out of a tire with a sledge hammer or doing medicine ball slams. As an all round core exercise are either of these better than the other, should they be supplemented with crunchies etc? Would you even recommend them? If you recommend the hammer or medicine ball slams what weight do you use? I've no way to get a massive tire to the house so would a smaller tire do? Any advice greatly appreciated.