Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Excellent for strengthening core muscles

I have used this product in VHS for years. I literally wore the video tape out. Now I have a new DVD player and searched for the DVD version as I love this ab workout. I began using the tape in my 50's. I am now in my 60's and it has solved low back pain problems for me as well as giving me definition that I have never had in my life. I highly recommend this product.