Chris and Xand are asking how to get fit fast. To find out, two pairs of twins who currently don't exercise but want to are putting two government-advised fitness regimes head to head. Fran and Jess are busy mothers with five young kids between them. For the last few years neither of them have had the chance to think about going to the gym let alone actually attend. They are being joined by Pete and Jem, who are almost 60 years of age and admit the last time they went into a gym was when they were at school! Team Xand are going for the slow and steady approach - 150 minutes of exercise a week at a moderate pace where their heart rates get to about 60% of their maximum. Meanwhile team Chris are going all in - their exercise is going to be intense but the advantage is that they only have to do 75 minutes per week, 45 of which is at maximum effort. It is tortoise versus hare - both regimes are known to improve fitness but which will improve fitness the most?

Next, a story that is all about motion sickness, where a multitude of brave identical twins are putting their bodies on the line! Millions of Brits suffer from motion sickness but because many leading remedies can have significant side effects - including drowsiness - our want to find a way of treating nausea without pills - a way that could work for everyone! Half of the twins are going to be taking ginger, which has been used by sailors for centuries. Moreover, there are a number of research papers suggesting that it might just work. Meanwhile, our other twins are going to be using acu-pressure bands. These simple bracelets push a plastic stud into a certain acupressure point on the wrist which a recent study in the US revealed could reduce post-operative nausea by as much as two-thirds. So which will work?

Finally in this episode, it is time for Chris and Xand to put their own identical twin brains on the line! This week, they have been inspired by the Bradley Cooper movie Limitless. The plot of this film involves the search for a mechanism to unlock the human brain's full potential and to make people 'limitless', where they can instantly become a kind of polymath genius. Sounds good right? Well with no movie-style pill yet available, Chris and Xand are putting two other treatments popular in silicon valley to the test. Chris is going with energy drinks. Touted as being able to give you wings, many people think downing a can of this stuff will give you an instant brain boost. But do they actually work? Show less