or

Fast Twitch                  Slow Twitch

100 mph from a standing start in less than

1 second, but they are designed purely to shoot

down a quarter-mile of drag strip tarmac. If

you wanted to cruise down a motorway at 100

mph (where that’s legal!) for any length of time,

you would choose an Aston Martin or a Bentley

– completely different animals from the drag

racer. You have the same sort of thing going on

with muscles in your body.

All of your muscles are made up of what are

known as slow-twitch and fast-twitch fibres.

Most of your muscles have a mixture of both,

but the big muscles like the soleus muscle in

your lower leg and the muscles in your back

that you use all the time simply to keep you

standing upright contain mainly slow-twitch

fibres. The muscles in your eyes that help you

give something a quick sideways glance are

mostly fast-twitch fibres. The different kinds of

fibres produce power in different ways. Slow-

twitch fibres need lots of oxygen to do their job,

which means they need a strong blood supply,

the oxygen in the blood providing the energy

to make the muscles contract. The slow-twitch

muscles deliver steady power over a long

period. Fast-twitch muscle fibres don’t need

so much oxygen because they produce a small

burst of energy, their muscle contraction being

over and done with in the blink of an eye. In

fact, that’s exactly what the blink of an eye is

– a fast-twitch muscle in action.

102  HUMAN POWERED AIRCRAFT

Your eyes, which you can move and blink

incredibly quickly, use fast-twitch muscle

fibres for blinking or making a quick sideways

glance, whereas your legs use slow-twitch

muscle fibres for standing and walking. You

can teach the muscles in your legs to act more

like fast-twitch fibres, and that’s what athletes

like Usain Bolt have to do to produce the

explosive power delivery that made him the

fastest human on the planet. Obviously years

of training are required for that and there

are some things that scientists have proved

help with the training – such as the

humble beetroot.

Beetroot juice is packed full of nitrates which

your body converts into nitric oxide, and this

has the effect of widening the blood vessels to

increase blood flow while also reducing the

amount of oxygen that the muscles need to do

their job. Lots of top sports people swear by

beetroot juice, so it had to be worth giving it

a try, but beetroot superfuel alone wasn’t going

to get me to 450 watts for three minutes, so I

fitted a strain gauge to my own bike and got

down to some serious training.

Making sure that the human engine could do its

job was one part of the challenge, but the most

important part was the HPA itself, so it was

back to Southampton University to take a look

at the design and lend a hand in building the

aircraft that I was to fly.