Fast Bowling Stress Fractures: Research and Recommendations
A current hot topic in the cricketing world is the number of English fast bowlers suffering with lower back stress fractures. There has been a lot of chatter, some good, some bad, so we thought we would break down the research, put it into a nice readable format and give some usable recommendations for you to reduce your risk of suffering a stress fracture.
What is a stress fracture?
A stress fracture is essentially a small crack in the bone. If left undetected, these cracks grow and as they increase in size so does the pain & recovery time.
Why do stress fractures occur?
Fast bowling is a very unique movement for the human body to produce and is highly asymmetric. With this movement being repeated thousands of times over a career, there are bound to be risks.
There are site-specific bone adaptation responses to fast bowling, much like in other sports (1). For example, the bone mineral density (BMD) of the lumbar spine (lower back) of elite male fast bowlers, is higher when compared to batters, rugby players and a control group (2). Interestingly, this wasn’t the same finding when comparing elite female fast bowlers to batters, footballers and a control group (3). But, both male & female bowlers, including spin bowlers, were found to have a higher BMD on the L4 & L5 vertebrae on the opposite side of the bowling arm. What does this suggest?
First of all, no difference in females when compared across sports suggests that the increased volume of bowling in the male game plays a big part in the amount of stress put through the spine. Secondly, there is an adaptation to the lumbar spine specific to bowling, irrespective of sex & type of bowling. Bowling will increase the BMD of the vertebrae on the opposite side to the bowling arm.
So, if the BMD is higher, surely that means it’s stronger right? Correct. So why do so many injuries occur? The answer is all about volume. We know that for things to get stronger in the body, bone or muscle, first you have to cause a little bit of damage. That’s why we lift weights! The growth happens in the recovery from this micro-damage. But, if adequate time isn’t given to recover from this micro-damage, and the stimulus (bowling) is continued, that damage is going to increase.
How much rest is required?
This is where it gets complicated! Too much rest, and the positive adaptation in BMD will actually decrease and put you more at risk (3). This is why a lot of bowlers have repeat stress fractures as you are more susceptible after a period of not bowling.
Rest is required after a spike in bowling volume such as maybe a Saturday and Sunday game for the first time in the season. After a spike in volume, there is a 3-6 week delay before the injury would present itself so it is vital to get your rest in after a spike, even if you don’t think you need it! As a general rule, you should aim for 2 full days of rest after bowling but no more than 5 day days (8).
It is also important to mention that the only thing that will produce this bowling-specific adaptation in BMD is….you guessed it…bowling.
We hate the phrase “bowling fit” because people use it to have a blast at S&C! But, in this case, to get truly bowling fit, you need to bowl.
Fairly self-explanatory really. The need for S&C is to then improve your bowling performance (e.g. bowl quicker, maintain stamina through a long spell etc) and reduce the risk of injury. The technical risk factors of stress fractures can be reduced thanks to S&C, but we will cover that next. However, achieving the BMD increase which is unique to bowling will not be achieved from just S&C alone.
Technical Risk factors
A recent study looked into technical differences between bowlers with and without a history of stress fractures (4). Whilst there are numerous factors at play in the build-up to a stress fracture, the study shows that these two technical factors below independently increase the risk of a stress fracture. So, listen carefully!
Collapsing at back foot contact
Back foot contact is the the contact of your back foot against the floor after you jump following your run-up. The goal of back foot contact is to maintain as much linear momentum from the run-up into your delivery stride. Therefore, we want to spend as little time at back foot contact as possible. For the quickest possible transition, you need the most minimal amount of movement. If you aren’t physically prepared for back foot contact then you will see a lot of excess movement.
The first sign of this is the heel dropping to the floor, suggesting that the foot-ankle complex can’t handle the force. The heel touching the ground acts as a brake, which increases the amount of time spent in this phase. If that isn’t enough of a compensation for the body, then the next thing to go will be the knee. The knee will bend and this movement increases the time even more.
Your body is increasing the amount of time, by producing movement, because it isn’t physically capable of controlling the excessive forces you are asking it to. It’s self-defence.
So, we’ve had the heel drop, then the knee bends, and the next thing is the hip flexing (like when you squat or sit on a chair.) This is present in people who really collapse at back foot contact. There is always going to be a slight knee bend but when the hip flexes, you know that the body is really struggling to maintain that momentum safely. Large rear hip flexion has been linked to poor knee stability and pelvic control (5,6), further reinforcing the belief that it is flexing as a protective mechanism. The issue with it flexing to protect the knee, is it puts the body in a less optimal position to deliver the ball. Momentum and delivery height has been lost, so lateral lumbar flexion, lumbar extension & lumbar rotation will increase to compensate for the loss. All of these will subsequently increase the risk of a stress fracture over time. Independently, they may not be the key factor. But, increased hip flexion creates the need for compensatory movements that when combined over time, will certainly be a key factor.
Lower back extension at front foot contact
Front foot contact is the final foot placement before ball release. This is a fraction of time before you have done all you can as a bowler and the ball is on its way to the batter. This moment happens so quickly that you have no conscious control over it. So everything that happens up to this point is crucial to help you get into as optimal a position as possible with a nice high release point, braced front leg and preferably a trunk stacked over your pelvis.
However, in a similar way to increased rear hip flexion at back foot contact, there will be compensatory movement patterns to account for deficiencies elsewhere. A big one at front foot contact is excessive lower back extension, e.g the lower spine curving. Now, a little extension is okay but having your back look like a “C” is bound to put pressure in the wrong places.
Lower back extension in general occurs because of a number of factors. We often see that a lack of core strength, tight hips and poor thoracic mobility are all factors that increase lower back extension in athletes. All of these factors lead to increased anterior pelvic tilt which reduces lumbopelvic control and when this is put to the test under-speed, such as a bowling action, lumbar spine extension is inevitable.
When are fast bowlers most at risk of a stress fracture?
The typical age when stress fractures occur is between 18 and 22 as the volume of bowling increases (4).
The key for us is to look at the key technical risk factors and then the physical qualities that we can improve to reduce the risk of these. Then, we want to get our young fast bowlers very competent in these elements, whilst they are still growing up and learning both athletically and technically.
If you’ve got a young fast bowler with a strong foot-ankle complex, stable knees, mobile hips, strong core & glutes and mobile thoracic spine, then the likelihood of them having to compensate in their bowling action is reduced. Therefore, they aren’t exhibiting the two key technical risk factors and it is just a matter of being careful with their workload. Once a fast bowler has developed, it is very hard to then drastically change their action but not impossible. But, for the number of stress fractures to drastically reduce, helping junior fast bowlers become good athletes first is crucial.
How to reduce the risk of stress fractures
Avoid spikes in volumes
Manage your workload! A study looking at elite male fast bowlers showed that greater than 234 balls in a 7-day period tripled the risk of a stress fracture when compared to those who bowled less than 210 balls (7). Avoid long periods of not bowling to maintain BMD. You should aim for 2 full days of rest after bowling and no more than 5 days between spells of bowling (8).
Maintain momentum at back foot contact
Build a strong foot-ankle complex so you are very springy by incorporating plyometric exercises with short ground contact time such as pogo jumps. Stabilise your knees by getting comfortable on one leg and work on stabilising your pelvis to avoid a larger rear hip flexion angle. Mobilise and strengthen everything around your hips to do this!
Avoid extension of the lumbar spine at front foot contact
If you live with an anterior pelvic tilt, you need to work hard to learn not to! Loosen & strengthen those tight hip flexors, strengthen your core and learn to tuck your pelvis under by squeezing your glutes.
References
We highly recommend you watch the video in reference number 3!
1 - Kohrt, W. M. (2004). American College of Sports Medicine position stand on physical activity and bone health. Med Sci Sports Exer, 36, 1985-1996.
3 - https://www.youtube.com/watch?v=2ysvXE59Q3I
5 - Bayne, H., Elliott, B., Campbell, A., & Alderson, J. (2016). Lumbar load in adolescent fast bowlers: a prospective injury study. Journal of Science and Medicine in Sport, 19(2), 117-122.
6 - Olivier, B., Stewart, A. V., Olorunju, S. A. S., & McKinon, W. (2015). Static and dynamic balance ability, lumbo-pelvic movement control and injury incidence in cricket pace bowlers. Journal of science and medicine in sport, 18(1), 19-25.
8 - Hulin, B. T., Gabbett, T. J., Blanch, P., Chapman, P., Bailey, D., & Orchard, J. W. (2014). Spikes in acute workload are associated with increased injury risk in elite cricket fast bowlers. British journal of sports medicine, 48(8), 708-712.
