Recent simulations of the stretching of tethered biopolymers at a constant speedv (Ponmurugan and Vemparala, 2011 Phys. Rev. E 84 060101(R)) have suggested that for any timet, the distribution ofthe fluctuating forces f responsible for chain deformation is governed by a relation of the formP(+f)/P(−f) = exp[γf],γ being a coefficient that is solely a function ofv and thetemperature T. This result, which is reminiscent of the fluctuation theorems applicable to stochastictrajectories involving thermodynamic variables, is derived in this paper from an analyticalcalculation based on a generalization of Mazonka and Jarzynski’s classic model of draggedparticle dynamics [Mazonka and Jarzynski, 1999 arXiv:cond-mat/9912121v1].However, the analytical calculations suggest that the result holds only if and the force fluctuations are driven by white rather than colored noise; they further suggest that the coefficientγ in the purportedtheorem varies not as v0.15T−0.7, as indicated by the simulations, but asvT−1.