Speed Development and Sprint Mechanics
Speed is the quality most often trained by imitation. An athlete is shown a position, told to hold it, and expected to become faster — an approach that treats sprinting as a shape to be copied rather than as an output produced by a system under constraint. This guide collects what we have published on the subject: what happens mechanically during contact and swing, why acceleration and maximum velocity pose different problems, which training inputs plausibly transfer and which only look as though they should, and what measurement is required to tell the difference. The individual articles go considerably deeper than the summaries here.
Sprinting as a System
Rather Than a Set of Positions
Sprinting is not a mechanical output to be engineered from the outside. It is an emergent property of a complex adaptive system that includes the nervous system, musculoskeletal architecture, psychological state, training history, accumulated fatigue, and the environment in which the movement takes place. That framing is not a philosophical preference; it has direct consequences for what can reasonably be expected from an intervention.
From a dynamical systems perspective, sprinting is an alternating single-support gait characterised by strong inter-step coupling (Latash, 2008). The limbs do not act as independent actuators: they function as components of a coordinated system linked through the pelvis, trunk and centre of mass. If the goal is maximal sprint speed, the unit of analysis is therefore not the single leg but the stride cycle as an integrated whole — which is why isolating a joint and strengthening it rarely produces the change expected. The argument is developed in sprinting as a coupled locomotor system and in broader terms in beyond mechanics: understanding movement as a complex emergent phenomenon.
The practical implication is uncomfortable but useful: a cue, an exercise or a drill changes sprint performance only if it changes a constraint that was actually limiting the system. Most do not, which is why the same intervention produces a response in one athlete and nothing in another.
What Happens During
Ground Contact
At maximum velocity, contact lasts on the order of a tenth of a second. Within that window the limb has to accept load, orient force, and release — and there is no time for a corrective response. The leg is, in effect, pre-programmed to be stiff at contact: the stiffness is set before the foot arrives, by anticipatory muscle activation, rather than produced in response to landing.
Touchdown geometry determines what that stiffness can do. The condition associated with effective contact is a backward foot velocity approaching the forward velocity of the centre of mass, with the foot landing near or beneath the centre of gravity. Contact in front of the centre of gravity generates braking force regardless of how strong the athlete is. That geometry is not a position to be adopted deliberately; it is the emergent result of coordinated swing mechanics, pelvic control, trunk stability and elastic recoil, and it is the subject of foot-strike dynamics in sprinting.
Where leg stiffness is insufficient, the support phase lengthens and the musculature absorbs force passively instead of redirecting it, which costs both economy and speed. What stiffness is as a measurable property, and why the optimum depends on the task rather than being uniformly high, is set out in the role of stiffness, part one and part two. Whether "absorption" is even the right description of what happens is examined in does force absorption exist? The relationship between ground force and top speed is the finding the whole area rests on: faster top speeds are associated with greater force applied to the ground rather than with more rapid limb movement (Weyand et al., 2000), and the orientation of that force, not only its magnitude, distinguishes faster from slower sprinters (Morin, Edouard and Samozino, 2011).
The Swing Phase and the Hamstrings
Attention tends to concentrate on stance, but much of what limits sprinting — and most of what injures sprinters — happens during swing. Hamstring activation reaches high levels during late swing, frequently exceeding stance-phase activation, while the muscle is lengthening under load and decelerating the shank before touchdown (Schache et al., 2012).
This has a direct consequence for exercise selection, and it is where a large amount of training time is currently spent without justification. Exercises that produce high surface EMG activation of the hamstrings under short-range, low-load conditions do not meaningfully replicate the late-swing demand, however dynamic or sport-specific they appear. High activation is not the same quantity as high force at long muscle length under speed. The distinction is set out in hamstrings behaviour and movement expression, and the critique of the exercises currently circulating on that basis in hamstring tantrums: effective exercise or social media noise?
The same late-swing loading explains a specific pathology: proximal hamstring tendinopathy combines tension with compression at the ischial enthesis, and hip flexion angle therefore governs how an exercise loads it — the subject of proximal hamstring tendinopathy in speed-based athletes.
Swing mechanics also depend on structures above the limb. Pelvic and trunk control during rapid limb exchange determines how much of the swing action is available at all, which is why the spine in human locomotion and sport performance belongs to this discussion rather than to a separate one about core training.
Acceleration and Maximum Velocity are Different Problems
Speed is not a single quality. Acceleration and maximum velocity make fundamentally different demands and respond to different training inputs, and conflating them is one of the more common sources of wasted preparation.
Acceleration is a problem of horizontal force production against a body that is not yet moving fast, with longer contact times and a forward trunk orientation. Maximum velocity is a problem of elastic recoil and stiffness under very short contacts, where the limiting factor is often not force capacity at all. Without sufficient elasticity in the soleus, gastrocnemius, Achilles tendon and hip flexor system, an athlete will reach a ceiling in maximum velocity regardless of strength levels. The two cases are separated in power and speed: the metrics that actually drive athletic performance and in speed training: a systems approach.
In team sport a third case matters more than either: speed is almost never expressed linearly. Changes of direction impose their own mechanical and coordinative demands, and coaching them is a distinct problem from coaching straight-line running — the subject of putting change into delivering change-of-direction coaching sessions.
Training the Constraints that
Limit Speed
Transfer depends on whether training improves the constraints that actually limit sprint performance: force orientation under short contact times, pelvic and trunk control during rapid limb exchange, swing-leg acceleration and deceleration capacity, and tolerance to high late-swing hamstring loads. A programme that improves none of these will not make an athlete faster however well it is executed.
Two methods address those constraints with reasonable directness. Isometric work develops the neuromuscular qualities required for rapid force expression, allows force production to be trained at specific muscle lengths, and imposes minimal fatigue relative to its neural output — which makes it usable close to competition as well as in preparation. What it does not do is become sprint-specific by reproducing the look of a sprint position, a distinction examined in isometric training and speed development: what the method can and cannot do. Its placement within a speed programme is covered in integrating isometrics intelligently within a sprint program. Plyometric work develops the stiffness that short contacts require, and a defensible progression moves from lower-intensity, longer-contact exposures early in preparation toward shorter-contact, higher-stiffness demands as structural capacity increases, as described in plyometrics progressions.
The same test applies to exercises adopted on the strength of a plausible rationale rather than of transfer data: the hip thrust builds hip extensor strength, but the evidence that this reaches sprint acceleration is weak, which is the reappraisal made in the hip thrust and speed development. Where the athlete's own profile sets the starting point rather than the method, training the engine you actually have, a guest contribution by Daniel Guzman, argues that genes shape emphasis while phenotype testing still decides.
Deciding which of these constraints is binding for a given athlete, rather than applying the sequence that worked for the last one, is the part that does not generalise. It is also the part that sport science and strength and conditioning consulting exists to support.
Measuring Speed
and Power
The quality of a speed or power programme cannot be assessed by feel, or by how much weight moves. It requires objective measurement, and the instrument has to match the question.
Timing systems answer questions about outcome: split times, acceleration profiles, velocity at a given distance. Force platforms answer questions about mechanism: isometric mid-thigh pull and countermovement jump force–time characteristics give direct information about maximal force production, rate of force development and neuromuscular state, and squat and drop jumps add further windows onto reactive capacity and fatigue. Neither replaces the other, and a department with only one of them is answering only half the question — the argument made in from force to speed: why performance professionals need both force plates and timing gates.
Where to Start
Readers wanting the overall framework should begin with speed training: a systems approach, then sprinting as a coupled locomotor system.
Readers interested primarily in mechanics should start with foot-strike dynamics in sprinting and continue with hamstrings behaviour and movement expression.
Readers responsible for testing should start with power and speed: the metrics that actually drive athletic performance and from force to speed.
Full Reading List
Speed Training: A Systems Approach to Developing Speed in Elite Athletes — the framework for the whole cluster: constraints, transfer, and how a speed programme is structured.
Sprinting as a Coupled Locomotor System — why the stride cycle rather than the single leg is the unit of analysis.
Foot-Strike Dynamics in Sprinting — touchdown geometry, pre-programmed stiffness and what determines effective contact.
Hamstrings Behaviour and Movement Expression: The Great Debate — late-swing demand and why EMG activation is a poor guide to exercise selection.
Hamstring Tantrums: Effective Exercise or Social Media Noise? — a critique of the exercises currently promoted on activation grounds.
Power and Speed: The Metrics That Actually Drive Athletic Performance — separating acceleration from maximum velocity, and strength from power.
From Force to Speed: Why Performance Professionals Need Both Force Plates and Timing Gates — what each instrument answers, and why one alone is insufficient.
Putting Change into Delivering COD Coaching Sessions — change of direction as a coaching problem distinct from linear speed.
Beyond Mechanics: Understanding Movement as a Complex Emergent Phenomenon — the systems view that underlies the rest of the cluster.
The Role of Stiffness, Part 1: Understanding a Mechanical Property — stiffness as a measurable property at tissue, joint and system level.
The Role of Stiffness, Part 2: Task Demands, Trade-offs and Training Progressions — matching stiffness to the task, and progressing isometric and plyometric work.
Isometric Training and Speed Development: What the Method Can and Cannot Do — what isometrics contribute to speed, and why position-matching is not specificity.
The Hip Thrust and Speed Development: A Biomechanical Reappraisal — joint kinetics of acceleration, the force-vector rationale and what the intervention evidence shows.
Proximal Hamstring Tendinopathy in Speed-Based Athletes — tension and compression at the enthesis, and staged loading.
Genes First: Speed, Train the Engine You Actually Have — a guest contribution by Daniel Guzman on reading genetic profile as training emphasis rather than ceiling.
Related reading
Does Force Absorption Exist? · The Spine in Human Locomotion and Sport Performance · Integrating Isometrics Intelligently Within a Sprint Program · The Language of Movement: Rhythm as the Organizing Principle of Skilled Performance · Kinetic and Kinematic Chain Principles in Integrated Human Performance · Activation Reconsidered: What the Term Means and What the Warm-Up Actually Does · Elastic Bands in Sport Performance Training
Frequently Asked Questions
Does getting stronger make an athlete faster?
Sometimes, and the condition matters more than the answer. Strength transfers when force capacity is the binding constraint, which is more often the case during acceleration and in athletes with a limited training history. At maximum velocity the limiting factor is frequently elastic and coordinative rather than force-related, and in that situation additional maximal strength changes little. This is why the same strength programme produces a clear response in one athlete and none in another.
Is it possible to coach foot strike directly?
Not usefully, because touchdown geometry is an outcome rather than an action. Where the foot lands relative to the centre of mass is produced by swing mechanics, pelvic and trunk control and elastic recoil, all of which occur too quickly to be adjusted deliberately within a step. Cueing the landing itself tends to produce a deliberate, slower action that is less effective than what it replaced. The constraint has to be addressed upstream.
Do high-EMG hamstring exercises reduce hamstring injury risk?
High activation measured by surface EMG is not the same quantity as high force production at long muscle length under speed, and it is the latter that characterises the late-swing phase where most hamstring injuries occur. An exercise can produce very high activation in a short-range, low-load position while replicating almost nothing of that demand. Activation is a measurement of convenience, not of mechanical similarity.
How often should maximum-velocity work be programmed?
There is no established frequency, and the useful constraint is exposure quality rather than count. Maximum-velocity running requires the athlete to be sufficiently fresh to actually reach high speeds, since sub-maximal running does not provide the stimulus; and the high late-swing hamstring loads involved need to be accumulated progressively rather than introduced at full intensity. In team sport the practical limit is usually set by the competitive calendar rather than by a prescription.
Are timing gates sufficient, or is a force platform necessary?
It depends on what decision the data has to support. Timing gates establish whether an athlete is getting faster, which is the question that matters most and the one a force platform cannot answer. A force platform establishes why, by separating force production, rate of force development and reactive capacity. For monitoring outcome, gates alone are adequate; for diagnosing a limitation or guiding exercise selection, they are not.
References
- Latash, M.L. (2008) Synergy. New York: Oxford University Press.
- Morin, J.-B., Edouard, P. and Samozino, P. (2011) 'Technical ability of force application as a determinant factor of sprint performance', Medicine & Science in Sports & Exercise, 43(9), pp. 1680–1688.
- Schache, A.G., Dorn, T.W., Blanch, P.D., Brown, N.A.T. and Pandy, M.G. (2012) 'Mechanics of the human hamstring muscles during sprinting', Medicine & Science in Sports & Exercise, 44(4), pp. 647–658.
- Weyand, P.G., Sternlight, D.B., Bellizzi, M.J. and Wright, S. (2000) 'Faster top running speeds are achieved with greater ground forces not more rapid leg movements', Journal of Applied Physiology, 89(5), pp. 1991–1999.