Speed endurance feature image

Running Phases Part 3: Speed Endurance:

Now that we have spoken about both acceleration and maximal speed running it is time to turn our focus to speed endurance. Speed endurance, when spoken about in its standard form, is the ability for an individual to maintain a near maximal velocity for an extended period (3). This will range between anywhere from 10 to 40 seconds or 100 to 400 meters. The ability for an individual to hold a near-maximal speed will be greater in those that are highly trained than those that are not (3, 4). Speed endurance is referred to most when speaking about events ranging from 200m to 800m on the track. It is rare that a team sport athlete would run further than 100m in a single effort, however, commonly, they would perform multiple short sprint efforts with little rest between referred to as repeat sprint ability (RSA) (1, 3). The ability of a team sport athlete to do this is underpinned by the same physiological systems as that of speed endurance (1, 3).

AUSTRALIA – SEPTEMBER 25: Track & Field: 2000 Summer Olympics, Australia Cathy Freeman in action, winning 400M final at Olympic Stadium, Sydney, AUS 9/25/2000 (Photo by Bill Frakes/Sports Illustrated/Getty Images) (SetNumber: X61190 TK11 R7 F24)

What exactly is it that affects our speed endurance and repeat sprint ability? As with acceleration and maximal speed running our strength power and technique are all paramount to our performance outcome. Now, however, we also have a greater impact from our energy systems. Throughout this article we will take a close look at the energy system contributions during speed endurance running and how we can manipulate them in training to further improve our speed endurance capabilities.

Energy systems:

To begin we have three ways in which our body can produce and utilize energy during exercise, that being the ATP-CP system, the anaerobic glycolysis system and the aerobic glycolysis system. The ATP-CP system is when the body uses already stored energy in the muscles to produce energy at a rapid rate, this however only lasts for approximately 10 seconds (5, 6). The anaerobic glycolysis system is when glucose is turned into energy with limited amounts of oxygen, unfortunately, this does result in the production of some fatiguing by-products such as lactate and hydrogen ions (5, 6). It is for this reason that we can only rely on this energy system for a short period (10-40 seconds). The aerobic glycolysis system is when glucose is converted into energy in the presence of oxygen (5, 6). This energy system has no fatiguing by-products and can, therefore, be relied upon for and extended period (40 seconds to 90 minutes) (5, 6). It is, however, a slow way of producing energy and therefore if you are wanting to move fast your body will place greater reliance on the ATP-CP and anaerobic glycolysis systems. It is important to note that these systems do not work in isolation, rather working simultaneously with one energy system being dominant at any one time (5, 6).  Speed endurance and RSA are heavily reliant on the anaerobic glycolysis system so let’s break it down a little further.

A diagram showing the energy system interplay during activity.

When we use our anaerobic glycolysis system glycogen is converted into glucose which is converted into a molecule called pyruvic acid (6). Due to the insufficient amounts of oxygen in the muscles, two fatiguing by-products are produced, lactic acid and hydrogen ions. The lactic acid and hydrogen ions can then be converted to produce more energy (6).

Sounds like there is no issue right?

However, when there becomes a greater production of these by-products compared to the muscles ability to utilize and clear these products, they build up in the muscles inhibiting chemical processes that ultimately lead to energy production (5, 6). When this occurs we have a greater reliance on the aerobic system (where oxygen is available) and ultimately slow down due to the greater reliance on oxygen for energy production (5, 6). This is evident when watching a 400-meter race, at the elite level the athletes may be able to hold their speed for 300 to 350 meters, while after that point they inevitably begin to slow down (5, 6). It has been stated that for a 400-meter runner the anaerobic glycolysis system will be the predominant energy system used for 60% of the race while the aerobic energy system will become dominant over the last 30% of the race (5, 6). In a team sport, however, this may seem a little more difficult to see, rather than seeing them slow down on one continual effort you may see then perform less high-intensity efforts and/or have a reduced intensity during those efforts.

Fatigue setting in towards the end of a 400m race.

Then we ask the question of how are we best to train this energy system to allow ourselves or our athlete to run faster for longer or perform high-intensity efforts for a longer period?

One of the big factors when attempting to train any energy system is that you have the right work to rest ratios. This is referring to the amount of time you are working compared to the amount of time you are resting. When looking to target the anaerobic glycolysis system we want our rest period to be the same, double or half that of the work period so a 1:1, 1:2 or 2:1 ratios (5, 6). By doing this we are not allowing the body enough time to fully recover and replenish energy stores before performing the next high-intensity effort (5, 6). This means that as the efforts (or reps) continue there is an increased build-up of lactic acid and hydrogen ions in the muscles, again causing us to fatigue and slow down.

However, the more you train this system the greater ability you gain to be able to buffer the fatiguing effects of hydrogen ions and lactic acid (5, 6). This allows you to maintain a high velocity for an extended period, or continue to perform repeated high-intensity reps (1, 2). It is important to note that this does not mean that there is a decreased build-up of hydrogen ions and lactic acid within the muscle, rather just that you can with stand their fatiguing effects for a longer period before it causes you to slow down (2, 5, 6).

The following are some potential sessions that you could perform to improve your speed endurance:

4 x 150m [walk back recovery]

5 x 80m fly’s (30m build up in acceleration) [1min recovery between reps]

1 x 30 seconds (run as far as possible) [1min rest] run the remaining 400m distance

The following are some example sessions you could perform to improve your RSA:

10 x 100m leaving every 30 seconds

6 x 30m leaving every 10sec

8 x 60m leaving every 20 seconds


  1. Dawson, B. Repeated-sprint ability: Where are we? International Journal of Sports Physiology and Performance. 7: 285-289, 2012.
  2. Lockie, R. Murphy, A. Schultz, A. Knight, T. & Janse De Jonge, X. The effects of different speed training protocols on sprint acceleration kinematics and muscle strength and power in field sport athletes. Journal of Strength and Conditioning Research. 26(6): 1539-1350, 2012.
  3. Marcello Iaia, F. Fiorenza, M. Perri, E. Alberti, G. Millet, G. & Bangsbo, J. The effects of two speed endurance training regimes on performance of soccer players. PLOS One. 10: 100-116, 2015.
  4. Miguel, P. & Reis, V. Speed strength endurance and 400m performance. New Studies in Athletics. 19(4): 39-45, 2004.
  5. Ohkuwa T. & Miyamura, M. Peak blood lactate after 400m sprinting in sprinters and long-distance runners. Japanese Journal of Physiology. 34: 553-556, 1984.
  6. Plevnik, M. Vucetic, V. Sporis, G. Fiorentini, F. Milanovic, Z. & Miskulin, M. Physiological responses in male and female 400m sprinters. Croatian Journal of Education. 15: 93-109, 2013.

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