Yes, the BBC also used this "Synchronize Their Heartbeats" phrase in their headline. When you read the content, it's far less exciting. Heartbeats do not synchronize - that would really be news - and it lured me to click to the article. Rather, heart RATES go up and down together (nor do the absolute rates match). This is attributed to the known fact that heart rate changes during in-breaths (faster) and out-breaths (slower). To me it looks like the only news here is that choir members inhale and exhale together.