1. A computer implemented method of reducing noise in an ECG signal, the method comprising: wavelet decomposing an ECG waveform with a processor to produce a set of approximation coefficients and a plurality of sets of detail coefficients; and modifying the set of approximation coefficients with a processor to reduce noise attributable to subject motion during acquisition of the ECG waveform to produce a set of modified approximation coefficients, wherein the modifying the set of approximation coefficients comprises locally fitting adjacent subsets of the approximation coefficients to second order polynomials.