  Consider a family of smooth immersions $F(\cdot,t): M^n\to \mathbb{R}^{n+1}$
of closed hypersurfaces in $\mathbb{R}^{n+1}$ moving by the mean curvature flow
$\frac{\partial F(p,t)}{\partial t} = -H(p,t)\cdot \nu(p,t)$, for $t\in [0,T)$.
We show that at the first singular time of the mean curvature flow, certain
subcritical quantities concerning the second fundamental form, for example
$\int_{0}^{t} \int_{M_{s}} \frac{\abs{A}^{n + 2}}{log (2 + \abs{A})} d\mu ds,$
blow up. Our result is a log improvement of recent results of Le-Sesum,
Xu-Ye-Zhao where the scaling invariant quantities were considered.
