In size and parity judgment tasks, we investigated whether the activation of numerical quantity exerts an influence on motor response parameters such as response force. Results showed typically strong effects on reaction time of numerical distance in the size judgment task (Experiments 1 and 2) and SNARC-compatibility (Experiment 1) in both tasks, indicating that semantic quantity representations were activated. Response force, however, varied at most weakly with the numerical magnitudes of the digits. Our results place limits on previously suggested interconnections of the magnitude and response systems. Activations within the magnitude system seem to have a strong influence on the initiation and selection of which action to produce, but only a little influence on the dynamics of response production (i.e., response execution).