Jokes aside, any effort to integrate UAVs with training expands the frontier of technology and sports. The tennis drone hangs the ball via extremely thin string and drops it on command. It also has a downward-facing 4K camera for coaches to monitor the player's form and technique.

Is it gimmicky? Yes — in fact, it's just a DJI Phantom 3 commercial drone with a Virgin Active sticker on it. But it's also a step toward drones that could fire balls toward players at angles and velocities simulating professionals' shots. The drone is being trialled at Virgin Active's Northwood location, so head there if you fancy trying out the future of sports training.