Concentrate on good form in your running . Strides are 15-20 seconds of hard running, not an all-out sprint, but hard running. Your breathing will be labored, you will be working hard, and you will be moving fast. Strides help to improve your form, improve your efficiency, and they start to fire those fast-twitch muscle fibers to make you able to go faster. All good things.
From the Swedish FART - speed LEK - play.
An easy pace with fast bursts as you wish (75-85+% WHR)
Or (usually on a track) continuously 200 meters slow followed by 200 meters fast then 400 meters slow followed by 400 meters fast.
Take your marathon goal time in hours and minutes and convert this to minutes and seconds. For example, if your marathon goal time is 3 hours and 10 minutes then convert that to 3 minutes and 10 seconds. First do a easy warm up 5-10 minutes jogging and a few warm up exercises.
Next try to run 800 meters (approx 1/2 mile) at your converted time (3:10 in this case). Recover after each 800 by jogging or walking for the same amount of time, eg. 3:10 in this example.
Start with three or four repetitions per workout in the first week and build up each time you perform the workout.
A period of extremely slow running (barely above walking pace) in between the efforts in a speed session.
A gentle jog at below 60% working heart rate (WHR). Running at this intensity will help your body recover between harder workouts while still building your aerobic fitness and muscle strength.
Conversational pace (60-65% WHR). This is the speed at which you should do your long runs. It might feel awkward at first but it’s better to hold back initially and last the distance than set off too fast and burn out just a few miles later.
A comfortable but purposeful pace similar to your race (marathon) pace (65-75%WHR). The steady run helps teach your body economy and also familiarises you with the speed you should set off on race (marathon) day. After a few runs at this pace, make a note of your target heart rate as you’ll really need to stick to your guns in the first few miles of the race and avoid getting caught in the rush.
THRESHOLD (THR) or BRISK
Around your target half-marathon pace (85% WHR). ”BRISK” sometimes refers to half marathon pace while “THRESHOLD” refers to 10 mile pace. Often described as feeling ‘comfortably hard’. Aim to hit about an 8 on a perceived exertion scale of 10.
FAST – your 5k or 10k pace depending on the distance of the speedwork reps (85-95% WHR). Try to hit your 5k pace for reps measuring up to 400m and your 10k pace for reps between 800m and 1 km length.
SOURCE – Runners World magazine