I love the 100 meter sprints when the Olympics are on. I don't get up early for much but last year I got up everyday in the second week of the O's when the 100 and 200 meter sprints were on.
Every race has 5 replays but the relevant one in regards to this post is the view from the finish line looking straight down the track to the on coming sprinters.
It's during this particular view that can see each of the sprinters faces of which you'll see their cheeks wobbling all over the place, and in the case of Shirvo back in his day, other "bits" too!
The ability to relax when you are attempting to run at top speed is critical.
Try this out for size:
Sit on the floor with your torso fully upright, clench your fist as hard as you can so your arms all tense up (c'mon, you know how to do that part) and then pump your arms as fast as you can like your sprinting. Count your arm pumps.
After a quick breather assume the same position but this time extend and point each of your fingers not quite as hard as you can but about 75% and repeat the arm pumping action from before. Count your arm pumps again.
I bet you my left one you got more arm pumps on the 2nd set...well you should have.
When you clench up then all of your muscles go into state of isometric contraction which means there are no other contractions be performed which means you're not really going to get anywhere, let alone get there fast.
The secret your looking to unlock is to be able to contract and relax in a short as time as possible.
In my recent posts I have talked about forefoot dominance and stiffness and this ties in with each of them and somewhat overlap in how you'd train them.
In the video below I run through a few exercises to train relaxation.
The first exercises is times squats which are best performed with 25 - 55% of your 1 rep max for 3 - 10 seconds. The heavier the weight you use then the shorter timed sets you'd use. If the arm pumping example didn't work for you before then you'll definitely get what I mean about not being able to go as fast as you potentially can without the ability to relax during these. Full range of motion is necessary for these sets as you're focusing on speed so the range of motion used during footy is all you need which is somewhere between a 1/4 and 1/2 squat.
I then move into a russian sprint which trains the ability relax and then contract at the very end range of motion. You want to keep your hips level so don't turn this into a lunge jump where you aim to get up to give you room to switch your legs. By keeping your hips level of your starting position, you need to fully relax to generate the speed to get from end range to end range. 2 - 3 sets of 4 - 8 each leg is suitable here but stop each set once your speed and/or quality of movement decreases.
This type of training can also be used for the upper body through various movements with a drop and catch bench press being displayed by yours truly. So you're contracting somewhat holding the bar at lockout then when you drop the bar, you must relax in a millisecond to get under the bar to catch it where you then contract again very hard. As you catch the bar, stop it where you touch it, try not to catch it and have it lower a little bit in your hands. Again 2 - 3 sets of 4 - 8 can be used here again in the 25 - 50% range.
I actually have a bunch more of these I;'m using now that I'll post about later on when I've given them a good run through first.
Pop these in your warm up as you need to do these exercises in a fresh state to get the most out of them.