  We present a new extraction of the effective strong coupling constant
\alpha_{s,g_1}(Q^2). The result agrees with a previous determination and
extends the measurement of the low and high Q^2 behavior of \alpha_{s,g_1}(Q^2)
that was previously deduced from sum rules. In particular, it experimentally
verifies the lack of Q^2-dependence of \alpha_{s,g_1}(Q^2) in the low Q^2
limit. This fact is necessary for application of the AdS/CFT correspondence to
QCD calculations. We provide a parameterization of \alpha_{s,g_1}(Q^2) thatcan
equivalently be used to parameterize the Q^2-dependence of the generalized
Gerasimov-Drell-Hearn and Bjorken sums.
