Gaelic footballers and hamstring strain

The GAA season is well under way now and players are buzzing to be getting game time after putting in the hard training through the lockdown to ensure they are in peak physical condition. They have earned their stripes!! It’s 10 minutes into a game, you are chasing down a defender to win possession. You are sprinting as fast as you physically can and just before you reach the ball “snap”, your hamstring suddenly becomes strained, and you need to be subbed off due to injury. Players are left scratching their heads as to why this is occurring. “Why can’t they strengthen their hamstrings?” “How can a strong background in sport translate into injury prone hamstrings?”

Empirical evidence suggests that there may be a genetic predisposition to hamstring injuries, however, evidence supporting this theory remains inconclusive. Possible reasons for hamstring injuries are training errors such as lack of training load monitoring or neglecting strength training. Unfortunately, we cannot prevent injuries, we can only do our best to help reduce injury risk. Hamstring injuries account for up to 21% of total injuries in Gaelic footballers, with around 22% of players sustaining a hamstring injury each season (1). The hamstrings are the most frequently injured site (2), with 68% of injuries occurring to the dominant leg (3).

It has been theorised these injuries occur due to weakness in the hamstrings, with a significantly lower hamstrings to quadriceps strength ratio been observed in injured athletes (3). However, the research shows us there are several mechanisms that can be responsible for acute hamstring strains such as over stretching, weakness and biomechanics and these will be discussed in the remainder of this article.

Hamstring muscles

There are three main muscle that make up the hamstring group. These are (A) The biceps femoris, (B) The semimembranosus and (C) The semitendinosus muscles. The semimembranosus is most frequently injured during stretch like activities along with its proximal tendon (4). The semimembranosus also achieves the greatest activity levels (> 75%) during maximal sprinting (5), making it susceptible to strains in weaker or less flexible athletes. Additionally, semitendinosus and biceps femoris will attain activation levels up to 65 and 40% (5).

The 3 hamstring muscles

Over stretching

Stretch like activities that occur during running have been a suspected mechanism for hamstring injuries which occur during the late swing phase when the knee is fully extended, and the hip is in large degrees of flexion due to athletes running with an excessive forward lean (6,7). The mechanism behind hamstring injury occurrence during high-speed running is a failure of the muscle tissues to tolerate the forces applied during the high demanding task (8). Stretch like activities are also witnessed when kicking a ball and picking a ball up off the ground similar to the Gaelic football pick up. The eccentric contraction of the hamstring causes a stretch in the muscle fibres which produces numerous contractile structures within the muscle which can cause overload.

Weakness

Strength imbalance between the hamstrings and quadriceps have been suggested as the most likely cause of hamstring strains during field sports (9). Quadriceps dominance is typically when the quadriceps activate first during activities where co-contraction between the quadriceps and hamstrings are required, such as a deceleration movement following a jump or sprint. If the quadriceps are dominant during athletic endeavours, there is decreased resistance to anterior tibial stress that is typically produced by the hamstring muscle group.

Weakness can also be associated with bilateral deficits, where one limb is significantly weaker (10). Lack of eccentric strength appears to be the most significant form of weakness resulting in hamstring injuries (11). Athletes will not be capable of withstanding the high impacts and velocities. Increased impact during early stance has also been suggested to result in hamstring injury due to increased impact forces from the body propelling forward with an increased forward lean off the trunk (12).

Biomechanics

If over stretching is an issue, athletes will likely need to assess pelvis positioning because an anterior pelvic tilt will put the hamstrings into a lengthened position that may feel tight due to increased tension. When fatigued, the postural muscles have a tendency to become hypertonic (in a state of high muscle tone). This can result in athletes feeling increased tightness in the muscle e.g., the hamstring may feel extremely tight during high-speed running. This is because the primary postural muscles may tend toward hypertonicity in the low back and pelvic region include the iliopsoas, erector spinae, rectus femoris, and quadratus lumborum (13). This can increase the positioning of the pelvis to a more forward direction causing the hamstrings to become lengthened (Image 1b). Stretching the hamstrings when they are already in a lengthened position due to an anterior pelvic tilt will be a waste of time. It will feel good at the time due to acute nervous system responses which help relax the muscle group. Long term it will be favourable to perform corrective exercises that will orientate the pelvis to its neutral position, reducing the hypertonicity of the muscles and placing the hamstrings in their optimal lengthened position.

Lower cross syndrome
Anterior pelvic tilt

When considering the above mechanisms for hamstring injury and following athlete screening, we can then plan training interventions to help reduce any future injuries. The best methods I have found are to include injury prevention work into the team’s strength and conditioning sessions and to ensure all injury prevention training is not isolated. This results in greater buy-in from players and management.

Strength training

It is important there is high correspondence between hamstring exercise selection and how the hamstrings act during the late swing and early stance phases. To achieve this, we must consider the joint angles, forces, and velocities between the exercises and the most common injury mechanisms as discussed above. I give a more detailed guide on training recommendations in my FREE eBook, “Bullet proof your hamstrings” which can be downloaded here. The prime objective of strength and conditioning is to ensure the athlete’s safety by improving injury resistance. It is important that coaches do not become preoccupied with trying to develop one muscle group at the expense of another. Any imbalance between muscle groups can create potential injury risk. Remember, the weakest link in a chain remains a weak link.

To strengthen your hamstrings, it is important to train them using various methods (i.e., with and without weights). No matter how fit you are, you will always be susceptible to injuries. If your hamstrings are stronger, they will be less prone to injury and therefore less likely to affect your playing time. Injuries are a part of sport but it’s important to strive for injury reduction rather than injury prevention; prevention is a much harder task to accomplish.

In recent years there has been an increase on research regarding strength training. The methods that do exist suggest that strength exercises should be focused on the eccentric (or negative) element of the exercise. Eccentric training is where the muscle produces more force than normal while contracting, essentially lengthening under tension. Eccentric overload is one factor related to hamstring injury; it is important to strengthen the muscles to withstand increased overload. It has been reported that a significant reduction in hamstring injuries can be achieved from performing the Nordic curl under fatigue, i.e., at the end of a pitch training session (14). A Nordic hamstring exercise programme has been shown to effectively reduce hamstring injuries by 65%–70% (15). Furthermore, a 10 week Nordic curl program may likely increase hamstring torque by up to 11% therefore increasing the hamstring to quadriceps strength ratio (9). This is going to be very favourable for injury reduction as well as improve the force output of the hamstrings which may have transfer to sprinting and kicking.

It is extremely important to perform the Nordic curl exercise correctly. Weaker athletes do not have the physical capacity to maintain tension through the full range of motion and simply fall forward to the floor. This is counterproductive since the hamstrings are mostly strained during high-speed running when they are lengthened, and the knee is close to full extension just before early stance. So, holding tension close to a more extended knee angle is going to be more favourable.

Since the hamstrings cross the hip and knee joints, athletes need to train both knee extension and hip flexion for eccentric muscle contractions. The RDL is a great exercise to strengthen the hamstrings in relation to the hip joint (16). Both unilateral and bilateral versions are respectable choices. It must be noted, when performing the single leg RDL it is extremely important to ensure the hips remain balanced. An upward hip shift on the non-training leg can result in lower muscle contractions in the hamstrings because the body tends to shift in a lateral direction to maintain balance therefore shifting muscle activity towards the lateral thigh.

Sprint training

High-speed running has also been shown to help reduce hamstring injuries (5,17). The problem is when there is a difference between peak game sprint and training velocities, the risk of hamstring injury becomes elevated. In addition, some athletes strain their hamstrings when performing high speed running which may also be a fatigue issue. During peak velocities, the hamstrings can exhibit 8.95 ± 1.66N.kg-1 of force during the swing phase (18). Sprinting is the only true way to replicate these demands because our gym-based exercises can lack range of motion, high forces, and high muscle activation levels that match those of high speed sprinting.

As mentioned above, the semitendinosus, semimembranosus and biceps femoris will achieve activation levels up to 65, 75 and 40% respectively (5). These values are greater than the Nordic curl exercise which is regularly used for injury prevention and strengthening the hamstrings (5). Since higher muscle activity has been witnessed during sprinting it is important to perform maximal velocity sprinting as it appears to be the best exercise for maximal hamstring activation, therefore increasing tolerance.

In conclusion, there are many reasons why players may sustain muscle and tendon strains in their hamstrings; however, research indicates that over stretching, weakness, fatigue and biomechanics appear to be the most significant contributing factors. A balance between strength training and regular high-speed sprinting may be the best options to help reduce injuries. The GAA community needs to be more aware of this and to employ professionals to help reduce injury, so players do not miss game time and time off work. Injuries are not always avoided no matter how strong and fit the player.

References

1.         Danielsson A, Horvath A, Senorski C, Alentorn-Geli E, Garrett WE, Cugat R, et al. The mechanism of hamstring injuries – a systematic review. BMC Musculoskelet Disord. 2020 Sep 29;21(1):641.

2.         O’Connor S, McCaffrey N, Whyte EF, Moran KA. Epidemiology of injury in male collegiate Gaelic footballers in one season. Scand J Med Sci Sports. 2017 Oct;27(10):1136–42.

3.         O’Sullivan K, O’Ceallaigh B, O’Connell K, Shafat A. The relationship between previous hamstring injury and the concentric isokinetic knee muscle strength of irish gaelic footballers. BMC Musculoskelet Disord [Internet]. 2008 Dec [cited 2019 Mar 30];9(1).

4.         Heiderscheit BC, Sherry MA, Silder A, Chumanov ES, Thelen DG. Hamstring Strain Injuries: Recommendations for Diagnosis, Rehabilitation and Injury Prevention. J Orthop Sports Phys Ther. 2010 Feb;40(2):67–81.

5.         van den Tillaar R, Solheim JAB, Bencke J. COMPARISON OF HAMSTRING MUSCLE ACTIVATION DURING HIGH-SPEED RUNNING AND VARIOUS HAMSTRING STRENGTHENING EXERCISES. Int J Sports Phys Ther. 2017 Oct;12(5):718–27.

6.         Chumanov ES, Schache AG, Heiderscheit BC, Thelen DG. Hamstrings are most susceptible to injury during the late swing phase of sprinting. Br J Sports Med. 2012 Feb;46(2):90.

7.         Higashihara A, Nagano Y, Takahashi K, Fukubayashi T. Effects of forward trunk lean on hamstring muscle kinematics during sprinting. J Sports Sci. 2015 Aug 9;33(13):1366–75.

8.         Cuthbert M, Ripley N, McMahon JJ, Evans M, Haff GG, Comfort P. The Effect of Nordic Hamstring Exercise Intervention Volume on Eccentric Strength and Muscle Architecture Adaptations: A Systematic Review and Meta-analyses. Sports Med. 2020 Jan 1;50(1):83–99.

9.         Mjolsnes R, Arnason A, osthagen T, Raastad T, Bahr R. A 10-week randomized trial comparing eccentric vs. concentric hamstring strength training in well-trained soccer players. Scand J Med Sci Sports. 2004 Oct;14(5):311–7.

10.       Orchard J, Marsden J, Lord S, Garlick D. Preseason Hamstring Muscle Weakness Associated with Hamstring Muscle Injury in Australian Footballers. Am J Sports Med. 1997 Jan 1;25(1):81–5.

11.       Timmins RG, Bourne MN, Sheild AJ. Short biceps femoris fascicles and eccentric knee flexor weakness increase the risk of hamstring injury in elite football (soccer): a prospective cohort study. Br J Sports Med. 2016;(24).

12.       Mann R, Sprague P. A kinetic analysis of the ground leg during sprint running. Res Q Exerc Sport. 1980 May;51(2):334–48.

13.       Lowe W, Chaitow L. Chapter 8 – Hip and pelvis. In: Lowe W, Chaitow L, editors. Orthopedic Massage (Second Edition) [Internet]. Edinburgh: Mosby; 2009 [cited 2021 Jun 22]. p. 153–73.

14.       Small K, McNaughton L, Greig M, Lovell R. Effect of Timing of Eccentric Hamstring Strengthening Exercises During Soccer Training: Implications for Muscle Fatigability: J Strength Cond Res. 2009 Jul;23(4):1077–83.

15.       Petersen J, Thorborg K, Nielsen MB, Budtz-Jørgensen E, Hölmich P. Preventive Effect of Eccentric Training on Acute Hamstring Injuries in Men’s Soccer: A Cluster-Randomized Controlled Trial. Am J Sports Med. 2011 Nov;39(11):2296–303.

16.       McAllister MJ, Hammond KG, Schilling BK, Ferreria LC, Reed JP, Weiss LW. Muscle Activation During Various Hamstring Exercises: J Strength Cond Res. 2014 Jun;28(6):1573–80.

17.       Malone S, Roe M, Doran DA, Gabbett TJ, Collins K. High chronic training loads and exposure to bouts of maximal velocity running reduce injury risk in elite Gaelic football. J Sci Med Sport. 2017 Mar;20(3):250–4.

18.       Dorn TW, Schache AG, Pandy MG. Muscular strategy shift in human running: dependence of running speed on hip and ankle muscle performance. J Exp Biol. 2012 Jun 1;215(Pt 11):1944–56.

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