悪足掻き[waruagaki] useless resistance
一挙手一投足[ikkyoshuittousoku] slight effort
一足[issoku] pair (footwear)
一足[hitoashi] step
一足先[hitoashisaki] one step ahead

一足飛び[issokutobi] (at) one bound
逸足[issoku] fast runner
右足[migiashi] right foot
運動不足[undoubusoku] insufficient exercise
栄養不足[eiyoubusoku] malnutrition

逸速く[ichihayaku] promptly
音速[onsoku] speed of sound
加速[kasoku] acceleration
加速運動[kasokuundou] accelerated motion
加速度[kasokudo] acceleration

快速[kaisoku] high speed
快速電車[kaisokudensha] high-speed train
角速度[kakusokudo] angular velocity
急速[kyuusoku] rapid (e.g. progress)
減速[gensoku] deceleration