This article aims to provide a conceptual clarification, classification and basic knowledge about one of the most common injuries in sport: the hamstring injury.
Muscle function
The Hamstrings is a biarticular muscle group; It is the main knee flexor and is one of the hip join extensors. In addition, it also provides medial and lateral stability to the knee (1).
Figure 1. The hamstring muscle complex
Anatomy
The hamstrings muscle complex (Figure 1) are composed by:
Semimembranosus (SM)
Semitendinosus (ST)
Biceps femoris (BF)
Long head (BFlh)
Short head (BFsh)
The muscle origin and insertion of each of the hamstring complex are presented in Table 1.
Muscle
Origin
Insertion
SM
ischial tuberosity
proximal medial tibia
ST
ischial tuberosity (joint tendon with BFlh)
proximal anteromedial tibia, forming the Pes Anserinus complex together with the sartorius and gracilis muscles
BFlh
ischial tuberosity (joint tendon with ST)
External tuberosity fibula
BFsh
linea aspera, lateral intermuscular septum, and condyloid ridge of the posterior femur
External tuberosity fibula
Table 1. Anatomy of hamstring muscles complex
Classification of Hamstring injuries
The hamstring may be injured in the muscle, tendon or in the ischial tuberosity. Therefore, the injuries are also classified according to the affected area:
Proximal injury (ischial origin): tendinosis, partial tendon tear, or complete tendon tear with or without avulsed osseous fragment.
Distal injury: involves the distal tendons or insertion of the tendons in a similar fashion.
Central hamstring injury: involve muscle usually at the proximal or distal musculotendinous junction. There are the most common injuries.
Muscular injuries
On the muscle belly or musculotendinous junction, the hamstring muscle injuries are the most common injuries in soccer (2–4). Ekstrand et al. (4) found in their study with elite soccer players that these injuries represent the 12% of total injuries during the season and the sprinting and/or accelerations and decelerations actions are the greatest injury mechanisms. In addition, a recent systematic review showed a mean percentage of reinjury of 22.9% (2).
Muscular injury classification according to the severity:
Grade 0
Discomfort sensation caused by overloading or contractures. DOMS.
Slight fiber structural-damage. Edema (but non hematoma).
Prognosticated recovery time: 1-5 days.
Grade I
Muscle strain (microtear) of the muscle fibers. Edema.
It mostly occurs at the musculotendinous junction, and more often in the proximal area.
Higher reinjury incidence compared with others grades (5).
Healing: RICE and adequate training program.
Prognosticated recovery time: 1-2 weeks (6).
Grade II
Partial macroscopic muscle fiber disruption.
Edema and immediate functional impotence after the injury.
Prognosticated recovery time: 3-4 weeks (6).
Grade III
Complete disruption of the myotendinous unit, often with retraction and a gap between the torn ends.
It necessitates prompt surgical correction. Delayed reattachment is associated with loss of full function and therefore increased morbidity.
Prognosticated recovery time: ≥ 3-4 weeks (6).
There are different grades of severity based on recovery time (4):
Minimal injury: 1-3 days
Mild injury: 4-7 days
Moderate injury: 8-28 days
Severe injury: >28 days
Tissue damage
However, the injury normally comprises a spectrum of tissue damage (i.e. different grades and areas) and not only in a single grade injury (1). On the other hand, there are factors which increases the recovery time: presence of injury to the BF, the cross-sectional area (as a percentage score), the length of the injury, and injury outside the musculotendinous junction.
Tendon injuries
Although it is less common, tendons may also avulse from their distal insertions or proximal origins with or without an associated avulsed osseous fragment.
Tendinosis (chronic injury caused by an accumulation of small tears in the tendon that have failed to heal properly over the time).
Partial tear
Complete tear
Besides, the ischiatic tuberosity (muscle origin) injuries may be described according to a three-tiered method:
Enthesopathic change (osseous area where the tendon is attached).
Avulsion < 2 cm displacement of an osseous fragment
Avulsion > 2 cm displacement of an osseous fragment (normally requires surgical intervention)
The causes of enthesopathic changes may be due to a contusion, osteomyelitis (bone infection), or a more aggressive though rare process such as neoplasm (abnormal formation of new tissue of a tumoral, benign or malignant nature) should be considered with marrow signal change. In addition, they may be associated with a thickening of the cortical area of the bone or periostitis.
Finally, high-grade muscle, tendon, and chronic osseous avulsion injuries can lead to muscular atrophy over time (1).
I will post another publication about the recommendations and training program of hamstring injury treatment.
References
Hancock CR, Sanders TG, Zlatkin MB, Clifford PD, Pevsner D. Flexor femoris muscle complex: grading systems used to describe the complete spectrum of injury. Clin Imaging. 2009; 33(2): 130–5.
Pfirrmann D, Herbst M, Ingelfinger P, Simon P, Tug S. Analysis of injury incidences in male professional adult and elite youth soccer players: A systematic review. J Athl Train. 2016; 51(5): 410–24.
Dupont G, Nedelec M, McCall A, McCormack D, Berthoin S, Wisløff U. Effect of 2 soccer matches in a week on physical performance and injury rate. Am J Sports Med. 2010; 38(9): 1752–8.
Ekstrand J, Hägglund M, Waldén M. Injury incidence and injury patterns in professional football: The UEFA injury study. Br J Sports Med. 2011;45(7):553–8.
Petersen J, Hölmich P. Evidence based prevention of hamstring injuries in sport. Br J Sports Med. 2005;39(6):319–23.
Revista AMEF. Asociación Española de Médicos de Equipos de Fútbol. 2007.
If you have any doubt, do not hesitate to leave your comment. If you liked the post, share it on social media!
This article has been made based on the references showed, other studies reviewed but not showed and according to the experience and knowledge of the author. In this way, it may include subjective ideas and opinions not contrasted in the research.
This article aims to provide a summarized analysis and a guideless of injury epidemiology in soccer.
Soccer is an interaction sport characterized by the alternance of high-intensity actions, thus implying a high injury incidence (1,3). In recent years there has been an increased physical demands in competition, being more aggressive and requiring better physical preparation of players to withstand the match demands (4,5). In addition, considering the high number of matches in high-level soccer during the season, playing two matches per week over a long period of season (a total of 60-70 matches), it is logically understood the augmented injury risk of players in soccer practice (1,3). In this way, although several authors showed that a recovery time of 72 to 96 hours between two matches is sufficient to maintain the level of physical performance, it is not enough time to maintain a low injury rate (6). On the other hand, the player age, training load (TL), level of competition and training standard are some of the main injury risk factors (3).
The systematic review and meta-analysis performed by Pfirrmann et al. (3) with high-level junior and senior soccer players, it has been shown a total injury incidence of 2.0 to 19.4 injuries per 1000 hours of practice in junior players; and 2.5 to 9.4 injuries per 1000 hours of practice in professional senior soccer players, with the higher injury incidence found in competition. In the same way, Ekstrand et al. (1) accounted a total of 50 injuries per season by team, that’s 2 injuries by player. 57% of these injuries are in match whereas a 43% are in training sessions.
Main conclusions
Retrieved from the bibliography reviewed relative to the epidemiological analysis in soccer are:
There are more injuries in match than in training sessions.
The most common injuries are the muscle strain, ligament sprain and contusion.
Muscular injuries account for 30% of all injuries.
The most common body location is the thigh in both junior and senior soccer players. The following most common were the knee, the ankle and the hip/groin. In addition, this injury pattern is not affected by the player age.
Thigh strains represent the 17% of injury incidence and 7 of 10 injuries are in hamstrings.
Hamstrings strain: 12%
Quadriceps strain: 5%
Other injuries:
Adductor pain/strain: 9%
Ankle sprain: 7%
Medial collateral knee ligament (MCL): 5%
The high risk of hamstring strain reflects the high intensity of professional soccer.
Overuseinjuries account for 27 to 33% of the injury incidence. These injuries are caused by a repetitive stress without sufficient time to undergo the natural regenerative process.
2/3 of injuries are trauma injuries: 81% in match and 59% in training.
Severe injuries, which accompany longer recovery process and RTP, occurred more often during matches.
Most common severe injuries:
Hamstring strain (12%)
MCL knee sprain (9%)
Quadriceps strain (7%)
Adductor pain/strain (6%)
21% of all injuries are due to foul play: ankle sprain (15%), knee sprain (9%) and thigh contusion (10%).
Head injury: 2%.
Fractures represent only a small percentage of all injuries.
In young soccer players, the most severe injuries occurred in the range age between 14 to 16 years.
Reinjury (R-in):
The injury risk factors (RF) are 4 to 7 times higher for soccer players previously injured.
Ekstrand et al. accounted the R-in incidence for 12% of injury incidence in professional soccer players. However, there are differences in the research (9-30%) which author attributes for a better medical support in elite clubs.
R-in causes longer absences than new injuries.
Junior players had lower reinjury rate.
R-in are more common during training than match.
These injuries are overuse injuries.
There are differences in the injury incidence according to the season period.
Injury incidence increases towards the end of each half of play (fatigue).
The injury incidence during matches is influenced by the playing position: midfield players and defenders were the most at-risk groups*.
*However, although a there are authors showing differences between playing positions, a recent systematic review did not find enough evidence to provide general considerations of injury incidence by position (7). Only goalkeepers show lower injury incidence.
Table 1 shows a visual guideless of injury epidemiology in soccer.
Elite Youth Soccer Players
Professional Adults Soccer Players
Total Injury Incidence
From 2.0 to 19.4 injuries per 1000 h(+ severe on match and 14-16y than older adolescents)
From 2.5 to 9.4 injuries per 1000 h(the majority were moderate severity and ≤ 1 week)
Incidence on Match
From 9.5 to 48.7 injuries per 1000 h
From 8.7 to 65.9 injuries per 1000 h
Incidence on Training
From 3.7 to 11.1 injuries per 1000 h
From 1.4 to 5.8 injuries per 1000 h
Match-Training relationship
Match >x5 than Training
Higher during matches53% on match, 47% training
Most common injury types
Strains, sprains and contusions2/3 Traumatic – 1/3 overuse (*Prevention plans)
Ankle, knee, groin, lower limb*Fractures: small % but major injury
Groin, knee, ankle*Fractures: small % but major injury
Reinjury
Sprains (42.9%) and strains (22.9%)
15.3% of all injuries
+40% recovery time than initial injury
2/3 or 63% were overuse injuries
Most common during training
16% of Hamstring injuries
Overuse injuries
Needs + recovery time
Table 1. Guideless of injury epidemiological analysis in both junior and senior professional soccer players retrieved from the systematic review and meta-analysis by Pfirrmann et al. (2016)
References
Ekstrand J, Hägglund M, Waldén M. Injury incidence and injury patterns in professional football: The UEFA injury study. Br J Sports Med. 2011;45(7):553–8.
Guerrero-Calderón B. The effect of short-term and long-term coronavirus quarantine on physical performance and injury incidence in high-level soccer. Soccer Soc. 2020 Jun 7;00(00):1–11.
Pfirrmann D, Herbst M, Ingelfinger P, Simon P, Tug S. Analysis of injury incidences in male professional adult and elite youth soccer players: A systematic review. J Athl Train. 2016;51(5):410–24.
Bradley PS, Archer DT, Hogg B, Schuth G, Bush M, Carling C, et al. Tier-specific evolution of match performance characteristics in the English Premier League: it’s getting tougher at the top. J Sports Sci [Internet]. 2016 May 18 [cited 2017 Jan 29];34(10):980–7.
Carling C. Interpreting physical performance in professional soccer match-play: Should we be more pragmatic in our approach? Sport Med. 2013;43(8):655–63.
Dupont G, Nedelec M, McCall A, McCormack D, Berthoin S, Wisløff U. Effect of 2 soccer matches in a week on physical performance and injury rate. Am J Sports Med. 2010;38(9):1752–8.
Della Villa F, Mandelbaum BR, Lemak LJ. The Effect of Playing Position on Injury Risk in Male Soccer Players: Systematic Review of the Literature and Risk Considerations for Each Playing Position. Am J Orthop (Belle Mead NJ). 2018;47(10).
If you have any doubt, do not hesitate to leave your comment. If you liked the post, share it on social media!
This article has been made based on the references showed, other studies reviewed but not showed and according to the experience and knowledge of the author. In this way, it may include subjective ideas and opinions not contrasted in the research.
Last comments