The basic idea behind the experiment is to speed up the frequency of the pulses, or ticks, produced by the clock with force to push it ahead.
Digital clocks basically devide and count freqencys produced by crystal osciallators. Sounds like stressing the crystal could increase it's frequency. Could you build a crystal 'strain' guage?
This is clearly not a relativistic effect. It's far too large.
Sadly the original english is cryptic. No doubt the reporters understanding was also less then complete.