Sea quark and gluon polarization in the nucleon at NLO accuracy

We investigate the sea quark polarization in the nucleon by means of a combined next to leading order analysis to the recently enlarged set of inclusive and semi-inclusive polarized deep inelastic scattering data. Using the Lagrange multiplier method, we asses the uncertainty inherent to the extraction of the different spin dependent parton densities in a QCD global fit, and the impact of the increased set of semi-inclusive data now available. We comment on future prospects at RHIC and JLAB and their potential impact in the future determination of polarized parton densities.