How to qualitatively assess physical performance in football

Guillaume
13 min readSep 16, 2023

An introduction to qualitative analysis of physical performance in football, a scope drowned by its quantitative counterpart.

No time to waste — let’s dive in! Before we kick things off, we must establish the dimensions in which we analyse and interpret the game. Football (and other sports) is not a summation of phases, actions or dimensions — it is a free-flowing, chaotically looping sport.

I don’t see football through the four-cornerstone model of the English FA, yet I believe the four corners exist.

These four dimensions do not occur in isolation — every football action is a cognitively-controlled decision, informed through tactical interpretation and enabled by physical and technical capacities. Every action; from Lionel Messi’s goals in the World Cup Final to Tom’s crunching two-footed tackle in last week’s Sunday League.

In the public spaces, the tactical dimension is especially coveted by the masses, as a source for millions of words on ‘Tactical Analysis’. The social and psychological dimension is discussed through a scientific lens, and even the technical scope is somewhat popular in public analysis or commentary. Less covered, coveted and reported, however, is the physical dimension.

The physical scope of football is not overlooked in private or professional spaces, though. Herein lies the self-explanatory difference between quantitative and qualitative analysis; quantitative analysis would objectively measure the numbers and metrics, while qualitative analysis would look at the process, the movement, without computing it into numerical systems. At the professional level, the physical dimension is calibrated by tests and tools on a quantitative level: think of the medical tests, the pre-season testing and the in-season monitoring using GPS trackers and Heart Rate Monitors.

Philippe Coutinho during a medical examination for the Brazil National Team, 2018.

The majority of senior football coaches don’t have access to this equipment and data, however, and neither do the fans/analysts (fanalysts?) in the public sphere. There is a huge disclaimer, however. Quantitative analysis, performed through objective tests and quantified in metrics, will forever remain a better, and more reliable tool for analysis on this subject.

Nonetheless, I firmly believe this very physical dimension is crucial to performance, be it to every aspect of football, or even tactics or technical execution (if people wish to isolate that). Therefore, I bring forward the qualitative analysis of physical performance in football, to marginally improve the quality of discourse in the public sphere, and potentially the quality of coaching in the private spaces too.

Where is the physical dimension?

There is no straight line to draw on the borders of physicality; it could be the anatomical composition that influences football techniques and decisions, or you could isolate anthropometric traits. The physical force is not to be isolated through actions — tackles, aerial duels or shooting techniques — it is best divided into components.

The Five Components of Physicality

These five panels serve us the framework in which the article will knead an understanding (and hopefully, an appreciation) for the qualitative analysis of physicality. Before we officially go through that process, let’s take a brief introductory course on each panel.

  1. Speed

Speed is the capacity to execute actions quickly, from running the pitch to shooting the ball. That’s speed of movement and speed of execution.

2. Strength

Strength is the capacity to withstand contact with the body and perform actions throughout.

3. Power

Power is the capacity to show strength at speed.

4. Endurance

Endurance is the capacity to consistently perform actions for a long time, within the aerobic and muscular dimensions.

5. Agility

Agility is the capacity to perform different movements in a coordinated manner; for example changing direction.

The framework

The qualitative points of attention in this blog will be separated through the framework of those five components, even though, as it will point itself out, these layers overlap, and their borders are blurry.

With no further ado, here are ways to decipher physical components through a qualitative lens.

1. Speed

There are many ways athletes can show speed; from sprinting to running, to accelerating, re-accelerating, to decelerating.

Without pointing at numbers (top sprint speeds), the qualitative analysis would be what is considered the “eye test”. This ranges from noticing a player’s sprinting prowess — think of Daniel James or Kylian Mbappé, but also other realisations of speed: Rashford’s deceleration or Antony’s running gait.

Qualitative analysis would also be the observations of running and acceleration gaits and traits; how knee drive, weight distribution, and many other factors determine the fine margins in running economy, running efficiency, but also injury prevention.

An account to follow for this content, is @SpeedSolutions_ on Twitter.

https://twitter.com/SpeedSolutions_/status/1686445748819214337?s=20

Below there’s an example by myself on Manchester United’s Antony, who sometimes uses this peculiar running gait when sprinting at full tilt without the ball.

The player is arching their torso backwards, which sometimes gives athletes a false sense of higher speed. In fact, this gait slows down the athlete, as their leaned-back posture creates more resistance to forward movement.

A forward-tilted torso creates more forward movement, making the running more efficient. In some cases, the backward posture is a compensation technique to generate higher knee drive.

If you were to only read one sequence of this article, make it this one.

Speed in football is not one-dimensional as in certain disciplines of athletics or even swimming competitions — it is a situational component.

Being “fast” in football is not achieving a high top speed, of which a lot of statistics fly around without much context. Football is one of the most varied sports on a physical level, demanding sudden accelerations within the first 3 metres, occasional 30 metre sprints after a 180° change of direction, or a heavy deceleration while mastering the ball.

The ‘top speed’ measured usually occurs in those infrequent long-distance, uncontested sprints, while that does not represent the role of speed in football.

Acceleration is another aspect of speed.

2. Strength

Strength is the ability to withstand contact — it is not only raw power harvested from bench pressing and weight lifting, but also the technical capacity to use it effectively on the grass blades.

Qualitative analysis of this component would look at the prowess in ground and aerials duels, from shielding the ball to challenging for headers.

Strength in ground duels can be derived from staying upright. The player shielding the ball has to keep their center of mass between their feet, but also use their arm to shield and push the opponent away. Strong players manage to keep their balance and posture, with the weight between their own feet, while having upper body strength to push players too.
Less strong players will be quicker to lose their duels by not keeping the weight between their feet (“leaning on the other player’s feet”), or leaning by pushing with the arm.

This here is Kyle Walker, balanced on his feet, keeping a good posture, withstanding contact.

And here is Antony, leaning or barging into Zinchenko, instead of staying upright with an arm in front of Zinchenko’s path.

And here is Marcus Rashford, keeping a posture that doesn’t use his strength well. If you’re not convincingly stronger than the opponent (like Romelu Lukaku is), then barging into them like Rashford does here is not to be advised. It is best to create distance; keep the ball on the far foot, ‘lean on your own feet’, be ‘diagonal’ to the opponent and use your near arm to keep them away.
This barging invites you to be bundled over.

Strength is as much functional as it is raw, in terms of “having strength”, you need both to be successful. It is not a weightlifting competition (where there’s a lot of technique, to be fair), or gymfoot as Eden Hazard would say. The raw kilograms of dumbbells don’t win you duels. The correct technique paired with sufficient strength does.

3. Power

Power is the ability to perform your strength skills at speeds and your speed skills with strength.

When I type this, my first imagination is a player galloping through the midfield, withstanding hurling legs, carrying the ball in full stride. That is power.

As with all areas of sports, the correct technical execution or tactical decision is much harder to find when it is done at speed. This is why Kevin de Bruyne and Lionel Messi, who find the best solutions and execute them with a chef’s kiss spend years at the top of world sports.

The same goes for postures (which is strength and coordination). It is much harder to fend off pressure, contact and resist force at speed than in stand-still situations.

Powerful players will therefore be able to keep upright, hold a posture, and “stand their ground” under pressure or resistance at speed. The absolute top end of footballers will also make great decisions and execute them perfectly, at the end of that powerful action.

Like in the other categories, the borders are vague; most categories intertwine and rely on one another to exist. You can assess power not only in midfield-slicing runs, but also in any other sequences:

A part of power resurfaces in accelerations, that is (on a physiological level) pure power, the fast-twitch fibers.

That power is what allows those electric wingers to beat their opponents through those accelerations, like Jérémy Doku’s amazing bursts to create separation.

Of course, there are techniques to using your power as we discussed with strength. The difficulty here, though, is doing this at speed — demanding more coordination.

Furthermore, you see how between speed and power acceleration fit into both. The borders are obscure.

4. Endurance

Endurance is the primary dimension where we would talk about fitness. This is the area, where with contextualization, the quantitative analysis looks at the volume and intensity of sprints, long-distance runs, zones et cetera.

For the qualitative analysis, that’s not possible to perform the same objective degree. Nonetheless, with an appreciation for the role of endurance within the sport, we can spot interesting topics to dissect.

Football is not the sport where athletes run anything close to a marathon, half a marathon; nor is it a jumping competition, nor is it a repetition of multiple 100m sprint sets. Football is a sport with a randomized variation of those actions, in different orders, at different intensities, and in different contexts. Uniquely, there is a sort of ‘voluntary’ recovery period between every one of those actions.
A player might be making short, burstful movements in a high-pressing situation, go to ground to win the ball, and then have to stand up and make a 5–10 second recovery run to press the opponent on the ball. It’s often the quality and quantity of these recovery periods that determine the quality and quantity of your next actions; from shooting the ball to jumping out to press.

In senior football, you’re required to last ninety minutes. That’s not realistic, so players and teams conserve energy to be “on their game” whenever the game requires them to be.

A player can conserve energy through their running economy. Running economy is how the margins; from your running posture, to running gait and how you accelerate and decelerate, influence the physiological investment your body has to make. An economic running style requires little energy for good results.

One sign of a disadvantageous running economy is when players heavily decelerate when they do not have to — imagine a striker who made a run into the space, but did not get played in, and now breaks momentum and goes from 30 km/h to 4 km/h.

This deceleration technique accumulates and can lead to more fatigue. It is important to brake correctly; by phasing out of the run, possibly doing a little jogging lap around the defender and getting involved with play later. This is a simple detail, it is not ground-breaking for qualitative analysis of endurance, but it can help many, many players.

Football is stuffed with lots of high-intensity actions. This is the “goldmine” to gauge endurance levels. These actions

  • Sprints (to get onto a ball, to press)
  • Footwork (in the opposition box, defending close to the ball)
  • Duels

require and consume a lot of energy. Players who are tired will execute these actions (any action, but high-intensity actions in particular) to a lesser standard than usual.

With regards to sprinting and running, you can recognize patterns. For one, we talked about how efficiently athletes decelerate. Another is the backwards-leaning posture discussed under the speed segment, which is a mechanic that could suggest fatigue.

There is also the body language. Of course, this is fairly subjective literature, but this is where, in a high-performance environment, you show your application and attitude.

Extreme signs of disinterest; half-hearted pressing sequences, throwing arms, not doing your task and jabbing at others, and many others can be tell-tale signs of not only physical performance but also mental fortitude.

In terms of endurance, it could be interesting to look at when this body language starts acting up. When this happens before about 55–60 minutes, there’s a right to worry.

A more reliable source to qualitatively estimate endurance is during those actions that require a lot of energy. Defensive footwork, where the defender is usually asked to be dynamic, on their toes, skipping or jockeying slightly to match his opponent, is draining physically.

Tired bodies, that have been demanded usually ~ one hour of intense, elite-level performance, will drain, and tiring actions will not be performed at the same level of quality. We (and yes, elite athletes too) return to natural movements.

The same is true for all of football’s actions — think of the intensity at which players close down the ball in dangerous situations, think of how well they prepare themselves to win second balls, think of how they’re (not) ready to follow the ball for a rebound off the goalkeeper.

The dimension of endurance is best estimated through quantitative analysis, but for fans, qualitative analysis can also indicate signs of physical prowess or lack thereof.

5. Agility

Unlike the suggestion in the cover photo, agility in the physical sphere is not the flexibility or mobility of an athlete’s joints or muscles. Agility is the capacity to change direction effectively, or change speed. It is not necessarily doing a quick 180° around your axis, but rather how well you can accelerate and decelerate in different directions.

A football-specific example is an attacker who makes a long curved run to stay onside, then has to adjust his run to protect the ball from the defender again. That’s agility.

Spotted by Joel Adejola, this clip is a good example of agility. It is the change of direction at speed.

For every player, it will differ; some find it easy to turn direction at high speeds, and some struggle to do so. Even for the same player, it will be different to turn to the right or the left. Football’s difficulty is also the added task of mastering the ball during that run.

A few important talking points surrounding changing direction efficiently:

  • Use the outside foot to re-direct your path
  • Place your foot “under your shoulders” — not outside of your imaginary vertical column
  • Angle your toes towards the new direction
  • Explode away

Garnacho’s fault in the clip above is how he uses his body weight to turn at speed; leaning the right shoulder inwards to shift his momentum inside. It does not get the desired effect, rather makes him lose his balance.

Agility is, again, not the kung fu kicks, but rather how you accelerate and decelerate in new directions. It is also how you ‘turn your pace’ like Kylian Mbappé and some other world-class athletes are capable of. That is the extra acceleration we talked about earlier under speed and power.

Concluding the blog

This blog is not a complete summary of qualitative analysis — there are more educated people than me who delve into the mechanics of sprinting and running, which is highly interesting.

The point is to introduce the possibility of this realm of analysis, and how there is value to this subject. Finally, a few names to mention on this uncharted territory of public analysis;

Sébastien Chapuis, whose tweets taught me a lot of the content that you read above

Skaar Performance, whose ‘Speed E-Book’ taught me details of speed and agility mechanics

The people at Ghent University, whose lectures inspire the scientific backbone of my football knowledge

This piece was written by Twitter user @guillaumevdwege, Movements & Sports Science student, UEFA B candidate, C-licensed coach and Level 1 PFSA Opposition Analyst. Disagreements, answers and questions can be directed to their Twitter profile.

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Guillaume

UEFA-Licensed Football Coach, writer, PFSA-licensed Analyst and Fan. Account belonging to @guillaumevdwege on Twitter.