When you ask anyone about common swimming injuries, most will bring up the shoulder, some will mention the knee, but the spine still represents a significant portion of swimming-related injuries, particularly in the elite population. Some research has found that anywhere between 30% and 50% of butterfly and breaststroke swimmers experience lower back pain.
If we think about the position of the torso and hips during butterfly and breaststroke, a swimmer spends a lot of time with an increase in lumbar extension to clear the water in front of the body for breathing. 
This increases the stress on the lower back and factors such as poor core and lower back muscle strength, flexibility and endurance can play a significant role. While MRI scans do not show a correlation with pain/symptoms in this population, a significant increase in disc degenerative changes was seen in elite and amateur swimming populations compared to a control group. There was no major difference between male and female populations, however, duration, intensity and frequency of swimming did play a role in the occurrence of disc degeneration, particularly around L5-S1.
While freestyle also incorporates some level of lumbar extension, butterfly and breaststroke certainly present an increase in load and risk of lower back injuries occurring. As such a mix of swimming strokes should be performed to modify the load during training while minimising excessive height for breathing during breaststroke and butterfly. Decreasing the use of fins, pull buoys and kickboards can also decrease the amount of time spent in the excessive extension of the back. Core and lumbar strengthening, flexibility, and endurance, as well as manual therapy for pain relief, have shown to assist with minimising injury and symptoms. Ensuring adequate rest or modification of training intensity, duration and frequency as well as a gradual return to sport and correct rehabilitation and
