It really depends on how hard you are hitting a muscle group. If you are doing a light total body workout, than you could get away with hitting it again 24 hours later. If you are really hammering a particular bodypart, you would want to give it 48 hours of rest.
James 1:16-17 ESV
Do not be deceived, my beloved brothers. Every good gift and every perfect gift is from above, coming down from the Father of lights
With God's help...Mens sana in corpore sano