The pulse oximeter wont work - it sits on a finger which has to stay motionless, and has significant motion artifacts.
The best way is a 24 hour ECG which is a small recorder with electrodes attached to the chest - very easy to apply and the subject will be unaware. but expensive in comparison.
The Polar pulse system is next best - I have used it with remote measurement on treadmills, but I havent used one which records.