Heart rate measurement in presence of noise can be a realistic problem. Recent gym equipment often provides heart rate measurement, e.g. through hand electrodes. The ECG signal is superimposed by other muscle action potentials which can have a similar frequency range. ECG signal extraction is quite difficult under these conditions.Why are you adding noise? The person being tested should not be sneezing all the time. With a properly designed circuit using an instrumentation amplifier IC like an AD620A and a right leg common-mode interference cancelling feed then the real noise is low.