Heart rate has spiked to 208 and 193. Is this a problem with the watch?

There are 3 or 4 possible causes which only you can decide

• The spike could be real (this is the worrying one)
• your watch band is slightly too loose, allowing your watch to move on your arm during vigorous movement and detect a “noisy” signal. See Wearing your Apple Watch - Apple Support for the recommended fit and band tightness. (This is the most frequent one, and easy to demonstrate by deliberately moving the watch on your wrist for a minute or two)
• there could be an intermittent fault in the sensor (very uncommon, and sensor problems tend to be all or nothing permanent failures)
• your watch picked up some electrical interference (unlikely unless you work next to heavy electrical equipment or radio transmitters)