Near the end of the first half of the Arsenal’s 2-0 win over Watford, which pushed their unbeaten streak to nearly seven games, Petr Cech swung through on a routine goal kick and went down to the ground in pain. Clutching at the back of his thigh, he immediately asked for a sub:
Based on the movement and his instant reaction, I was nearly certain of a hamstring strain (if you’ve ever tweaked a hamstring, Cech’s “clutching of the backside of the leg” pose may have brought back some memories). The hamstring injury was confirmed after the match by Manager Unai Emery, who further posited that Petr Cech could miss “two to three weeks”, and recently the team announced Cech is expected to miss three to four weeks.
The average return to play for footballers from hamstring injuries is approximately 17 days. The longer than average rehab timeline (upwards of a month) for Petr Cech clues me in that his hamstring strain could be a lower end of the spectrum grade 2 hamstring tear (any “strain” is a tear in the muscle btw, don’t let that word scare). A grade 2 tear (using the recently finalized British Athlete Classification system) involves a tear in 10-50% of the muscle fibers.
To gain a better understanding of the injury and what we can expect from Petr Cech for the rest of this season, I’ll take you through the following:
- The “mechanism of injury” aka how it happened
- Some potential underlying causes unique to Petr Cech
- Long-term ramifications
Buckle up, here we go…
I. Petr Cech Hamstring Mechanism of Injury
As you saw in the video, Petr Cech strained his hamstring during a kicking motion. This is a common mechanism for hamstring injury in footballers for two reasons:
1 – The hamstring decelerates (“brakes) the lower leg during the follow-through phase of the kicking motion:
To complete that task, the hamstring has to contract while lengthening. This is known as an “eccentric contraction”. In contrast, a “concentric contraction” is when a muscle contracts while shortening. I created the following visual, using the example of a biceps curl, to illustrate the difference:
An eccentric contraction is significantly more stressful on the muscle. In fact, the soreness you feel after a workout is more often than not due to the eccentric portion of the weight-lifting. It’s no coincidence that nearly all hamstring strains happen during this eccentric portion of movement, as we saw with Petr Cech.
And now the second reason…
2 – Combined forceful hip flexion and knee extension during the kick follow-through puts additional stress on the hamstring:
The combination of these two factors puts a large stress on the hamstring. If there comes a point when the stress on the hamstring is greater than what it can tolerate, a tear is likely to result. Additionally, there are underlying factors which can weaken the hamstring and decrease their stress tolerance. I’ve highlighted two of these in this case…
II. Underlying Risk Factors for Petr Cech
The first risk factor for Petr Cech was age. According to multiple studies (click here, here, here, here, here, here, and here for more info), the older you get, the more likely you’re to injure a hamstring. Specifically, athletes 23 and older are up to 3.9 times more likely to injure a hamstring and athletes 25 and older are up to 4.4 times more likely.
Generally, the overall risk for hamstring injury increases by nearly 30% every year after the start of a professional soccer career (there are different theories as to why hamstring injury risk increases with age and you can read about those here or here).
Petr Cech is currently 36 and on the doorstep of the 20th year of his career. That’s a whole lot of percents accumulated…and perhaps inversely correlated to the hair spikes:
The second risk factor for Petr Cech and his hamstring was fatigue. Research shows, across multiple sports, that hamstring injuries increase as fatigue sets. This may be due to decreased hamstring torque and/or strength deficits (click here, here, here, and here for more info) as fatigue sets in.
Not coincidentally, the injury occurred into stoppage time of the first half, a point at which fatigue has built up over the previous 45+ minutes of action.
Each of these factors may have a played a role in Petr Cech tearing his hamstring. He now moves onto the rehab process and once he’s cleared to play, what can the team expect going forward….
III. Risk of Re-injury & Long-Term Ramifications
The most reliable risk factor, by far, for future hamstring injury is a a previous hamstring injury. Research shows that players with a previous hamstring injury are two to six times more likely to have another strain (click here, here, here, here, here, here, and here for more info).
Further, most of these re-injuries happen within the first two months after returning to sport with increased risk thereafter (click here, here, and here for more info). Some studies have shown that the risk for re-injuring a hamstring is three times higher than a non-injured player for up to a year after the initial strain.
Regardless of his position or sport, Petr Cech is at significantly higher risk of re-injuring that hamstring during the next two months and at an increased risk of hamstring re-injury over the next year. Additionally, playing at the highest level of competitive soccer puts more strain on the hamstring which leads to potential for injury. Research bears that out (click here and here for more info) as top flight players suffer a higher rate of hamstring injuries compared to lower divisions.
One key positive for Petr Cech is that the goal keeper position doesn’t involve that much running, especially high speed running, as compared to other positions. Running quantity has been linked to increased hamstring injuries (click here, here, and here for more info).
IV. All in All
Due to the touchy and sensitive nature of hamstrings and the importance of his position, I expect the Arsenal medical staff to be quite conservative with Petr Cech. The research clearly shows that a shorter rehab time is associated with an increased risk for re-injury (click here, here, and here for more info). If and when he gets back, making it through the first two months without re-injury will be critical for his prospects this season.
However, if I haven’t hammered this home by now, hamstring tears are notoriously sensitive and prone to re-injury, especially when you’re putting them through the paces of high stress kicking movements. It wouldn’t surprise me in the slightest if Cech does re-aggravate the hamstring at some point and Leno is called on again for an extended period of time.
This season may become Leno’s opportunity to grab hold of the first team keeper reigns and reinforce the potential we saw during the Watford match.