The Apple Watch has saved several lives thanks to its heart rate monitor, which has been able to provide advance medical warnings to those who might have died otherwise. The new Apple Watch Series 4 adds a fall detection, designed to respond to a situation where the user has fallen and can't get up. If the Apple Watch detects a fall, it will "tap" the person wearing the timepiece, sound an alarm, and give the user several options to choose from, including making a call to emergency services. If the watch detects no movement for about a minute, it starts a 15 second countdown. At the end of that period, it will automatically make that emergency call.
A story in Swedish publication AftonBladet discusses what happened to 34 year old Gustavo Rodriguez, who had been cooking when he experienced severe back pain that felt like a knife twisting in his back. Rodriguez ended up collapsing on the floor, right in front of the hot stove he was using. Fall detection worked perfectly, tapping the man's wrist, sounding the alarm and asking whether Gustavo wanted the watch to call for help. Even though his phone was in the next room, the Apple Watch could have saved the day by summoning an ambulance. Instead, Rodriguez decided to call his mother-in-law, who lived close by, and she drove him to the hospital.
The important thing to take away from this story is that fall detection on the Series 4 version of the Apple Watch is a feature that works, and could save a person's life. Fall detection is set "on" by default for users 65 years of age and older. Younger wearers can enable the feature at their discretion. But since anyone can fall, it probably is a good idea for all Apple Watch Series 4 wearers to have fall detection turned on, no matter how hold they are.