Do you feel as if you could run forever at one pace but have trouble “picking up” the pace for shorter races? Do you think you might not be running to your potential? Has your performance plateaued with high mileage training? If you answered yes to these questions, chances are you’re lacking a properly structured programme incorporating appropriate amounts of speedwork.
What is speedwork?
Speedwork, or interval training, is simply defined as bouts of high-intensity running separated by periods or rest, walking, or low-intensity jogging. But since intensity is relative to each individual’s maximal level, speedwork is not necessarily always conducted at a fast pace. That’s why sports experts prefer the term interval training, as speedwork often conjures up images of elite athletes churning out sub-60 second 400s.
It’s all relative
Some people say “I can’t do speed training because I’m not fast!” But that’s analogous to someone who needs to lose weight saying “I can’t go on a diet because I’m too heavy!”
In most instances, it’s the slower runners who have the most to gain by incorporating some form of interval training into their programme. In fact, it is only a select few individuals who actually need to do interval training at a really fast pace. The pace of the interval is always based on some percentage of your max level (peak treadmill running speed, 5-km time trial speed etc.).
Therefore, “speed” for one person may be an easy jog for another. For example, a very talented 12-year-old girl conducts her speed sessions at a pace of approximately 3:45/km, while the high school girls cross country team average a pace of about 5:00/km for a similar level of exertion. You need to experiment a bit to find the pace that’s speed for you!
Physiological adaptations
There are a number of established physiological benefits to performing interval training. Firstly, interval training will raise your maximal aerobic capacity or VO2max. Your VO2max is an indicator of your maximal ability to produce energy aerobically (with oxygen). Assuming a given level of efficiency, the more aerobic energy you can produce, the faster you can run.
Interval training also raises your running economy, which is simply how efficiently you run. If you become more efficient, you will be able to use less oxygen (and energy) to run at any given speed.
Therefore, you will be able to maintain a faster speed at the same level of oxygen consumption. Improvements in efficiency largely account for the continued improvement in performance in runners whose VO2max gains have plateaued.
Interval training will also improve your ability to buffer lactic acid. This is a particularly important adaptation for races of 10 km and shorter, because significant lactic acid production occurs at the intensities of these shorter races. While lactic acid does not appear to be a direct cause of fatigue per se, it is associated with an increased level of exertion and pain.
With interval training, the brain and central nervous system will learn the recruitment patterns necessary to run at faster speeds. You will never feel comfortable running at race pace if you have not developed efficient neuromuscular recruitment patterns. This is something observed in a lot of marathoners and half-marathoners.
Both marathon and half-marathon pace are usually run at a faster pace than a normal training run. However, many runners just log a lot of mileage at a slow pace and never really practice running at goal marathon or half-marathon pace before the race. Then they wonder why the pace feels so uncomfortable during the race!
Finally, interval training will help you develop an innate sense of pace, especially if your intervals are conducted at a wide range of different speeds. This adaptation is particularly useful for choosing a starting pace in a race, where the general tendency is to go out too fast.
Lessons from the lab
Scientific literature has conclusively shown that increasing training intensity is the best way to induce beneficial physiological adaptation and improve performance. And the best way, or course, to increase your training intensity is to incorporate interval training because you can complete a greater total volume of intense running if it is divided up into shorter intervals.
Several studies have shown that it takes over double the amount of training time to attain the same fitness gains with a low-intensity training programme as with a high-intensity training programme.
While increasing intensity has been associated with improved performance in a number of investigations, a significantly increased training volume (mileage) has been associated with a decrement in performance and symptoms of over-training.
This is good news for people with busy schedules, because a high-intensity, low-volume training programme not only improves your fitness more than a high-volume, low-intensity programme, it also takes less time.
Findings from the field
Mile (or 1500 m) race pace is one of the best predictors of performance potential at any race distance up to the marathon. This is also evidenced by the fact that today, most world-class male marathoners have mile PBs (personal best) close to or under four minutes. Even the winners of major ultra-marathon races, such as Comrades and the 100 km World Championships have 10 km PBs of under 29 minutes.
What this shows is that to perform well in the longer races, you first need to first focus on getting as fast as you can in the shorter races. The faster your max speed is over a shorter distance, the faster any given percentage of that speed will be in a longer race.
Putting it into practice
At this stage, you’re probably wondering how you should work all these guidelines into your programme.
If you’ve never performed interval training before, start with one short session per week (not more than 1,5 km of high-intensity intervals) and gradually increase the volume, eventually working up to two interval days per week.
There are a range of paces and distances at which intervals can be conducted. Obviously though, the emphasis should vary depending on your primary race distance. However, in order to stress all the body’s physiological systems, intervals should be conducted at a variety of different distances and speeds.
The details of different types of intervals are listed in Table 1 and will guide you in structuring appropriate sessions. Inappropriate high-intensity running will lead to a higher injury risk, so it’s always best to conduct your interval training under the supervision of an experienced coach or exercise scientist. Some of the hallmark dos and don’ts of interval training is also listed below.
Table 1:
Interval type
Interval distance
Pace
Interval volume per session
Work: Rest ratio
Race emphasis
Short
100 - 400 m
400 m - 1500 m, race pace
1,5 km - 3 km
1:4 - 1:6
800 m - 3 km
Medium
600 - 1000 m
3 km - 6 km, race pace
3 km - 8 km
1:1
3 km - 10 km
Long
1200 m - 2 km
10 km - 21 km, race pace
4 km - 10 km
1:0,5 - 1:1
10 km - 42 km
Tempo
2 km - 5 km
15 km - 42 km, race pace
6 km - 15 km
1:0,25
15 km - ultra
The dos and don'ts of interval training
Dos
Don'ts
Allow at least 48 hours between an interval session and any
other hard training session.
Increase weekly mileage at the same time as
increasing/introducing interval training.
Reduce weekly mileage if legs aren't recovering between
sessions.
Finish a session feeling like there's nothing left.
Introduce interval training gradually.
Conduct interval training if you're sick.
Speed or interval training is an often-neglected component to a well-structured training programme. Interval training will induce important physiological adaptations more efficiently – with less risk of over-training than high-mileage running. These adaptations will enhance performance at all race distances provided that the interval sessions are appropriately implemented.
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