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RUNNING PHASES PART 1. ACCELERATION

Running Phases Part 1: Acceleration

Acceleration is a hugely important part of most sports, whether that be leading for a mark, accelerating to hit a drop shot, running from a pack or simply exploding from the blocks in a 100m sprint. Your ability to accelerate and accelerate efficiently is the key to generating speed quickly to perform these tasks (3).

Acceleration training should be a major focal point of all athlete’s training where their sport involves some sort of speed and explosive power. This is especially evident in change of direction based sports where having the ability to produce high speeds over short distances (0-30/50m) is paramount (7, 8), while having the ability to react and accelerate quickly can be the difference between first and second place in track events.

Acceleration is the rate at which the speed of an object is changing from a stationary position or slowly moving state to maximum speed (6, 7). This generally occurs over 0-30m or within 4 seconds (8). Once the athlete moves past this distance, they move into reaching their maximum velocity or speed. There are three key factors that aid in us accelerating quickly; strength, power and technique (1, 2, 6). We will talk more about these throughout this article, whilst discovering the most efficient way to accelerate.

Strength

Firstly, let us look at what exactly strength means in the context of exercise and sport. Strength is your ability to apply force against a load or resistance. This could mean applying force to fend off a player in a tackle, to a racquet to hit a ball, or in this context to the ground to drive yourself forward horizontally. When we talk about force in the sprinting and acceleration context, the greater amount of force we can apply to the ground combined with the speed at which we can do it, the greater reduction we can have in our ground contact time (GCT) (1, 2, 5). GCT is the time the foot is in contact with the ground per stride (1, 2, 5). GCT differs when comparing the initial acceleration phase to the mid-acceleration phase, indicating that there is a difference in strength qualities (maximal strength, explosive strength and reactive strength) required as we progress through the acceleration phases (1, 2). Let’s discuss each of these in more detail.

Maximal Strength  

To put it simply maximal strength is the maximum amount of force that you can apply to an object, or ultimately a measure of how strong you are (6). This can be measured via a 1 Repetition Maximum (RM) test (the total amount of weight that you can lift for one rep) (6). When your 1RM is derived from compound lower body lifts such as a squat or deadlift, we gain insight into how much force you can apply to the ground. Of course, being able to produce high levels of force is of no benefit to acceleration if you can’t express this quickly, or throughout the running pattern. Maximal strength can be best developed through compound lifts:

Worlds Strongest man performing a Deadlift.
  • Squat
  • Deadlift
  • Romanian Deadlift
  • Bench Press
  • Bench Pull

Explosive Strength

This is the ability of our muscles to apply maximum force to an object or the ground in minimal time (1, 2). If we think of the rate of force development curve (the rate at which we are able to produce force) explosive strength is simply the tip of that curve (1, 2). Explosive strength is commonly measured via a standing vertical jump test or broad jump test. Combining this measure with your maximal strength measure can provide an indication of the amount of force you can apply to the ground and how quickly you can change from an eccentric (muscle lengthening) to a concentric movement (muscle shortening) (1, 2). Some activities we can do to help develop our explosive strength include:

Olympic Weightlifting Clean and Snatch.
  • Olympic lifting derivatives
  • Kettlebell swings
  • Medicine ball throws

Reactive Strength

Now we start to put the two together, where reactive strength is our ability to rapidly change from an eccentric to a concentric muscle contraction also known as the stretch shortening cycle (1, 2, 6). This pertains to our ability to hold elastic energy within our tendons as they act like a spring, being stretched to their maximum capacity before being released (1, 2, 6). Some common ways of developing this type of strength includes various plyometric exercises such as:

Hurdle Jumps with a short contact between.
  • Drop jumps
  • Pogo jumps
  • Hurdle jumps

Power

Power can be explained as the change in force with respect to time, the speed at which force is applied is proportional to the amount of force that is applied (1, 2). This is different to explosive strength as it is not necessarily the maximum amount of force we can apply (2). Power is important during acceleration as when we talk about the GCT, the faster we can apply force to the ground the more rapidly we are able to move (1, 2). For example, the amount of force and the speed at which you apply that force to the ground in walking is far less than that of a run, and then again of sprinting (1, 2). As you progress through the acceleration phase your ground contact time shortens indicating a greater use of power than explosive or maximal strength (1, 2, 6). Some of the common ways we can develop our power include:

Box jumps.
  • Box jumps
  • Squat jumps
  • Non-countermovement hurdle jumps

Now that we understand the need to apply high levels of force quickly to move fast, let’s look at the best way to do that making us as efficient as possible.

Technique

There are many technical factors that can be looked at during the acceleration phase, and all phases of running for that matter, to make us more efficient. We will be looking at three key factors:

The First Three Steps

The first three steps of our acceleration phase whether it be for a straight-line sprint or to a change of direction, are important. Getting the initial stages of the acceleration phase right will have a flow on affect to the subsequent stages of the acceleration phase. So, what do we want our first three steps to look like?

It is important that as we take our initial movements to accelerate our steps are low and short. As we move through our acceleration phase these steps will get larger and our heel lift higher (4, 7, 10). It is ideal that these steps are fast, however initially they will be a lot slower than that of maximal speed steps (4, 7, 10), needing to apply high levels of force to produce movement.

Triple Extension

Triple extension is when we form a straight line from our shoulders to our ankles (9), the ideal position to adopt at toe off during all stages of running, but more importantly during the acceleration phase. This position allows compliance through the posterior kinetic chain, linking together our larger muscle groups (erector spinae, glutes, hamstrings and calves) to work together in a synergistic manner to achieve the same common goal (move us forward fast) (9). When we lose triple extension, we break the kinetic chain, resulting in muscle groups working in isolation to achieve the same goal (9). This quickly depletes efficiency and increases our chances of sustaining an injury in muscle groups which are adopting a greater load to compensate (9).

Forward Lean Position

Lastly, our forward lean position places the whole body’s centre of gravity is ahead of the base of support, bringing the trunk closer to the ground reaction forces (9), and in combining this position with triple extension we are able to apply greater amounts of force to the ground (9). This forward lean position means that we are able drive the ground behind us with every step, rather than potentially overstriding and creating a breaking force with every step (4). This position will be far greater in the initial stages of acceleration, slowly transitioning into a more upright maximal speed position. Think of yourself as a jet aeroplane slowly increasing your height as you move forward.

Asafa Powell showing triple extension, forward lean and low, short initial steps.

Here are three drills that can aid technique in these areas:

Wall March

A March & A Skip

Falling Start

References:

  1. Balsalobre-Fernandez, C. Tejero-Gonzalez, C. Campo-Vecino, J. & Alonso-Curiel, D. The effects of maximal power training cycle on strength, maximum power, vertical jump height and acceleration of high-level 400-meter hurdlers. Journal of Human Kinetics. 36: 119-126, 2013.
  2. Barr, M. Agar-Newman, D. Sheppard, J. & Newton, R. Transfer effect of strength and power training to the sprinting kinematics of International rugby players. Journal of Strength and Conditioning Research. 28(9): 2585-2596, 2014.
  3. Coh, M. Jost, B. Skof, B. Tomazin, K. & Dolenec, A. Kinematic and Kinetic parameters of the sprint start and start acceleration model of top sprinters. Gymnica. 28:33-42, 1998.
  4. Harland, M. & Steele, J. Biomechanics of the sprint start. Journal of Sports Medicine. 23(1): 11-20, 1997.
  5. Hunter, J. Marshall, R. & McNair, P. Relationships between ground reaction force impulse and kinematics of sprint-running acceleration. Journal of Applied Biomechanics. 21: 31-43, 2005.
  6. 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): 1539-1550, 2012.
  7. Mero, A. Komi, P. & Gregor, R. Biomechanics of sprint running: A review. Journal of Sports Medicine. 13(6): 376-392, 1992.
  8. Murphy, A. Lockie, R. & Coutts, A. Kinematic determinants of early acceleration in field sport athletes. Journal of Sports Science and Medicine. 2: 144-150, 2003.
  9. Nagahara, R. Matsubayashi, T. Matsuo, A. & Zushi, K. Kinematics of transition during human accelerated sprinting. Biology Open. 3: 689-699, 2014.
  10. Standing, R. & Maulder, P. The biomechanics of standing start and initial acceleration: Reliability of the key determining kinematics. Journal of Sports Science and Medicine. 16: 154-162, 2017.

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