The benefits are amazing. Juice has to be fresh in order to optimize the nutritional value. Optimum Nutrition = Optimum Performance. Why juice as opposed to smoothies?
“The advantage of this is we can consume large quantities of nutrient-rich juice without taxing our digestive systems with all of that fibre. Imagine juicing three or four medium size carrots – approximately a glassful of carrot juice. Once drunk, the carrot juice would be absorbed into your system in about 15 minutes. Now imagine eating all of those carrots with all of that fibre. It would take some time to break them down and the energy required from your digestive system to do so would be much greater.”
Read more about it: Nutrition: The Benefits of Juice (Athletics Weekly)
Also, a good juicer is most important – I have an Omega juicer – easy to use- easy to clean.