Before revision:  This gap mainly stems from the four main dynamic factors in sEMG-based gesture recognition: gesture intensity, limb position, electrode shift  and transient changes in the signal . These factors are hard to include within an offline dataset as each of them exponentially augment the number of segments to be recorded.
After revision:  This gap mainly stems from the four main dynamic factors in sEMG-based gesture recognition: gesture intensity, limb position, electrode shift and transient changes in the signal ), as including their permutations drastically increases the amount of data to be recorded.