INTERVAL TRAINING – What is it and how it can help your running? By Anna Fitzgerald.

Whether you are relatively new to running or a seasoned athlete, most distance runners can get speed and strength benefits by introducing some type of interval training into their programs.

Interval training can be complex and highly personalised at the advanced or elite level, but it is not only for advanced athletes. Coaches manipulate, adjust, and incorporate interval-training stimuli over a period of time in their programming to achieve desired improvements. However, everyone can get an improvement from adding some sort of interval training into their weekly training repertoire. In fact, it plays a critical role in elevating the performance, speed and speed endurance of all runners helping them to go faster for longer. There are countless possible variations to an interval session depending on what you want to achieve and how your body responds to different training.  Sometimes, this fact makes the notion of interval training seem daunting to newer runners or runners seeking to self-coach, but it need not be the case.  I hope to broadly simplify what can be a confusing topic, provide you with some example sessions and give you some tips, so you can have a go at incorporating intervals into your own training.

What is it?

Interval training is running segments of various lengths with rest periods in between.  Rest can be active (jogging) or standing.  Each run/rest segment is a repetition. Repetitions are often divided into sets or groups of repetitions with a longer rest interval between each set. The nature, effort duration, rest duration, number of repetitions and intensity of an interval session depends primarily on its the purpose and the type of event distance targeted by the runner. Equally, each of these elements can be manipulated to get different training responses from an athlete.

Purpose

Broadly, the purpose of incorporating interval training into your running program is to achieve an improvement in:

• your top-end speed and your ability to maintain it (anaerobic threshold).  This is the sprint zone;
• your speed endurance.  In other words, your ability to maintain hard aerobic running for longer; and
• your running strength or power.

When to introduce them?

For beginner runners’ interval training should be introduced after base running fitness levels have been established. This is important to minimise the risk of injury. Natural speed improvements come from building your underlying fitness levels first and then, hill-based sessions are a great starting point as the risk of injury associated with these types of efforts are lower than with other types of intervals.    As your strength, flexibility and fitness levels increase it is then appropriate to incorporate some longer intervals close to race pace, and then finally, to build your top end speed.  For beginner distance runners trying to incorporate intervals for the first time the following progression is ideal:

Base running fitness development→ hill intervals→ aerobic intervals→ sprint intervals

Hill Intervals

Hill intervals are training gold for a distance runner and particularly those just starting out.  Compared to flat surfaces, hills reduce the impact on your legs by limiting your range of motion. This lowers the risk of muscle strains and pulls.  They build muscle, power, and strength therefore increasing running efficiency when you get back to running on level ground.  Hill efforts force you to recruit a greater number of muscles to perform the running motion; require you to increase the force you put through your legs; encourage correct foot placement; and naturally elevate your heart rate.

How steep?

Broadly, as the gradient of the hill increases the duration of the repetition decreases.  This means that long hills are performed on a gradual slope and would last longer than short steep ones.  Long hill intervals ideally last between 2 to 3 minutes and are run at a medium-hard intensity. A jog recovery is usually recommended as these types of hills are used to build aerobic capability, fitness and speed endurance. A moderate hill interval session would be run at a hard effort of about 30-60seconds rep duration, and a steep hill intervals would last approximately 10-30 seconds and would be run at over speed or faster than 5km race pace. Coaches often add short hill strides to longer runs to prepare the body for a faster running the next day and to help fire the neuromuscular system.

Hill Interval example sessions:

• 4-8 x long hill intervals (jog back recovery)
• 10-15 x moderate hill intervals (jog back recovery)
• 4-6 x steep hill sprints (walk back recovery)

The beauty of hill intervals is that you can adjust the effort to your level of fitness.  Accordingly, you can manipulate the session to cater to your needs by: changing the number of repetitions; lengthening or shortening recovery time; changing the nature of the recovery from a walk to a jog, run or standing recovery; and changing the surface or gradient of the hill. As with everything, work with your capabilities and build slowly.

Long intervals

In distance runners, long intervals are used to extend aerobic speed endurance.  That is, their purpose is to develop your ability to run faster for longer before fatigue levels take over and slow you down dramatically.  They are usually incorporated into a 5km or 10km program together with steady state runs and threshold runs which have essentially the same purpose- to have you spend time at your maximum aerobic capacity (or VO2 max). In simple terms, this means that in every repetition you should aim to run at a hard pace at or faster than your 5 or 10km race pace. If race pace means little to you, another way to put it is to consider it hard running that is at the point at which it feels tough but sustainable for the length or duration of the interval.

The length of repetitions vary greatly in this type of workout however, they are usually somewhere between 400m and 2kms.   For a distance runner, anything shorter starts to creep into the sprint interval zone and anything longer starts to counteract the purpose of these sessions by decreasing the speed at which you can run. Ideally, the session would have you spend a total of 10-30mins at this level of effort with rest periods in between. If you were running shorter repetitions such as the 400s then you would have more reps in the set so that the desired aerobic energy system is triggered. There are lots and lots of combinations that can be utilised. A couple of my favourites are:

• 5 x 5min (2min recovery)
• 4-6 x 1km reps (90 second recovery)

It matters not whether the fast part of the interval is time-based or distance-based. Generally, longer interval sessions are completed with a jog recovery over a rolling with 60 seconds to 2mins recovery between reps. Shorter rest intervals will obviously decrease your speed but can be used to increase the overall intensity of the workout.  You can also play around with the duration of the efforts varying them while keeping the rest interval the same (for example: 5min, 4min, 3min, 2min, 1min (2min recovery)).

As with any speed work, build gradually and work with your capabilities. Listen to how your body responds and consider your overall training. Don’t be scared to shorten the length of the hard interval or to incorporate a standing or walk recovery instead of a jog, where appropriate. These sessions are tough and they build both stamina and mental strength.  I encourage you to play around with various combinations, get creative and have some fun.

Sprint intervals

Sprint intervals for are used to develop your top end speed.  They improve your leg speed and running economy. They can also glean neuromuscular adaptations or in other words, improve the co-ordination between your nervous system and your muscles.  They are usually short and performed at a pace that is at, or close to maximal speed.  Runners need to be mindful that they remain relaxed throughout these efforts, as there is often a tendency to tense up making injury a real possibility. Accordingly, start slower, aiming for 90-95% of maximum speed in the first rep and then build to top end by the final repetition.

For beginner runners wanting to incorporate this type of interval into their training, a great place to start is by adding 3-4 strides of 60m-100m in length at the end of an easy run. As they are all out sprints, walk back recovery is ideal.  Finally, coaches of middle distance runners and more advanced runners may use sprint interval training to improve an athlete’s lactic tolerance levels.

Helpful tips

• Aim for consistency in your repetitions. That is, despite your fatigue levels, the final repetition should be the same (if not a little faster) than your first.  A common mistake is for beginner runners to get carried away and run the first repetitions too hard and then struggle to complete the session.  If you have slowed down markedly in your last rep, take heed and either shorten the duration of the hard rep, cut down the number of reps you have to perform, or slow them down. The goal of an interval session is to work hard and work consistently.
• Don’t skip the warm up or cool down. These are a crucial component of any interval session and they prepare your body for the hard efforts to follow.  A good warm up would include 5-15mins of jogging, followed by drills and run-throughs.  Shorter or faster sessions such as the sprint intervals often require a greater amount of time to be spent in the warm up phase to minimise the risk of injury.
• Adapt the sessions to your capabilities and fitness levels. If you are not capable of running a distance or you find the effort too long, adjust it to suit your abilities.  Once you are ready to progress, add distance, shorten your rests or add to the number of repetitions. There are countless opportunities for variation.
• Include others.  If you can recruit a friend or a training partner then do it.  Hard interval sessions can be easier with company.  There is also an immediate acknowledgement of your efforts because they have been witnessed and they can be a lot more fun with friends in tow.
• Consider risk. There is a direct correlation with the speed of an interval and the risk of injury.  Sprints and hard intervals on flat, hard surfaces are more risky than longer intervals or hill sprints. It often said that you should look to develop the general before the specific.  Hence, speed intervals should be left until the specific part of a distance runner’s training program or incorporated closer to race day, in order to get some final speed benefits.
• Think about the surface. Where you can, keep your hills and longer intervals off the road.  This will dampen the impact of the session on your body and help you to recover quicker. Even shorter intervals can be performed effectively on a flat grass oval.  While track intervals are precise, they can be very taxing on the lower limbs.
• Don’t judge the pace of your intervals by using your GPS. I suggest that you use your watch to time the efforts and rests only.  Ideally, turn the pace fields off or avoid looking at them altogether during the session.  For distance runners, interval training is about effort, it is not about hitting a certain pace. Apart from the inherent inaccuracies that GPS devices have, the speed at which you run the intervals are dependent on a variety of extrinsic factors.  You cannot control the pace at which you are capable of running on any given day but you can control the effort.

Finally, have fun with it all. If you’re still unsure, speak to a coach, join a group, jump online or speak to your running buddies.  There is a plethora of information available for all levels of runner and a whole world of interval training sessions for you to discover!

Anna is a Sydney Runner,  mother of two and RMA Ambassador. You can follow her journey here.