Calf Injuries in Football

In modern football, with its intensity and with its accelerations and decelerations, soleus injuries has become more common.


In a 2011 study by Jan Ekstrand; Epidemiology of muscle injuries in professional football (soccer), published by the American Journal sport Medicine, showed how injuries to the calf muscles accounted for 13% of the total injuries recorded.


In a 2017 study related to the analysis of a multi-sport champion, Brandy Green in her article; Calf muscle strain injuries in sport: a systematic review of risk factors for injury, published by the British journal sport Medicine highlighted how previous injuries in the same area and advancing age were important risk factors.


Managing important athletes but with recurring injuries to the soleus has become quite common in the Italian championship, for this reason the availability and use for the biomechanical (or for anyone involved in injury prevention) tool as Myontec MSleeve has become essential.


This tool falls into the category of wearable technologies, allowing the great advantage of performing an evaluation in a context of normal sporting activity, thus respecting the performance model and the specific sport gesture. It has an on-board sensor capable of analyzing, even at 100 hertz, the electrical activity of muscles such as the soleus, gastrocnemius, and tibialis.


In addition, in the same hardware there is an IMU (inertial measurement unit) sensor, also capable of recording all three-dimensional accelerations at 100 hertz together with the angular speeds and their direction thanks to gyroscopes.


The presence of the electromyographic signal at the tibial level is also important for football. In fact, in running and in runners, the tibial stress syndrome was highlighted, a problem that requires a period of rest from sports activities. Michael J Arnold, Common Running Injuries: Evaluation and Management, Am Fam Physician. 2018 Apr 15; 97 (8)




How to Use It?

The advantage of wearable technologies is due to the possibility of evaluating the same athlete in a laboratory, therefore in an environment protected from variables, and on the pitch in a context that is highly specific to sporting activity and to the movements that are usual for the tested player. The possibility of having a comparison between these two different environmental conditions allows us to have an important series of additional information to evaluate the player realistically and correctly, therefore with a much higher degree of injury prediction ability.


In the laboratory we should be able to propose tests that are able to reproduce a specific sport gesture, in football for example a lateral shift of the load.

The image above, derived from a video, can inform us about the different activations of the calf muscles in the left or right lateral movement, informing us about the ability of the lower limbs of the subject to push laterally even with the ankle (for example in the presence of a functional limitation to the under astragal) and therefore the muscles close to it. Or simulate a strong deceleration from which to obtain important information preventive of the rupture of the cruciate ligament.


The use of gyros can provide useful information.


Based on the negative or positive sign of the gyroscopic data we can understand based on the entity of the data if the tibia rotates more inwards or outwards, in the first case a dynamic valgus attitude would be configured, an attitude at risk of breaking the cruciate if also in the presence of muscular imbalance.











How to Read the Data

IMU data explained in dimensions.


The colors next to the items help to see the trend of the graph. The first data on the left is the one read at the time of the vertical yellow line and represents the instant of stop of the video. Then we have the minimum (min), maximum (max) and average (m) data.



Gyroscopic data has a sign - in front of the number when it reads left and is unsigned when it reads right, this for the Y and Z axes. For the X axis the sign is - in anterior rotation indicating antero-rotation.


X is horizontal, reading the data from the pants, if we were to read them from the sensor of the MSleeves it would be X the vertical and Y the horizontal. The XYZ data is the result of the three registered accelerations. Since the accelerations themselves are vector quantities, we can apply the physical rule of the parallelogram to them, thus representing the three-dimensional control of the subject.


Let's now observe some data with the use of the new calf sleeves in a subject with joint stiffness of the right ankle and subject to many injuries on this side of the body.

When we have to evaluate the GRF or ground reaction force (i.e. ground force) we use the sensors on the calves (they are positioned vertically so the vertical is X) and we refer to the average data (the last one on the right m). You will notice the background area of the graph in a different color, this is a function of the Biomovie video analysis program and allows you to divide the data according to what we need to analyse. Therefore, we could evaluate the acceleration forces even in very short instants such as that of a time of contact of the foot to the ground.


Normally we analyse the data in amplitude, if we evaluate them in frequency we obtain the vibrations, another important parameter to be evaluated for preventive purposes. We note how on the right due to the articular block of the ankle the forces on the ground are on average higher. An increase in GRF will correspond to an exponential increase in the risk of overload injuries, putting more stress on the muscle structures of the subject.

We can see the activation of the right soleus during the change of direction, 177 microvolt.



The left soleus demonstrates less muscle activation than the right one, 83 microvolts.


We can also evaluate if in the change of direction movements, we have a greater knee valgus on one limb.

From the data we note a greater rigidity of the right limb. This is related to the reduced mobility of the ankle on the same side. The data can be highlighted by the minimum and maximum gyroscopic data on the X axis which represents the vertical axis.




Conclusion

The use of Myontec's MSleeves allow for a reliable, realistic, and repeatable field analysis. The amount of data that we can obtain from it helps us to confidently evaluate every athlete of every sport in any of his technical gestures.







Author

Article is written by Mr. Mauro Testa. He is Biomechanics Specialist at Biomoove Labs in Italy. Mauro has a notable CV showing a tremendous experience in Biomechanics, helping both individual pro athletes (cyclist like Peter Sagan) as well as pro Teams (AC Milan, Juventus, Torino, Bologna, Italian National Football Team etc.). See more at www.biomoove.com

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