No , The thing is that Physiotherapy doesn't weaken your muscle over time. Muscle disease includes a number of rare conditions, which in most cases tend to present at around the same age, and due to their progressive character, they can lead to physical limitations and reduced life expectancy. So Clear answer is Physiotherapy Never Weakens Muscle. but if you are taking Physiotherapic Treatment for a longer time you may feel that your muscles are stronger and with the blank gap in between treatment may lead to feeling of weakness.