In this article, I'd like to talk about body flexibility and injury prevention.
Have you ever been told that you need to be flexible because if you are stiff, you will get injured?
Have you ever wondered if there is any basis for this phenomenon that health care providers are all talking about? Have you ever wondered, "Is there any evidence for this phenomenon that health professionals are talking about?
As a medical professional, I've always had my doubts and had to be convinced by mysterious theories, but I found a study on it.
The research
Injuries are common in running and can be seen to affect up to 94% of recreational runners.
Health care providers often use features from routine musculoskeletal clinical assessments to assess risk of injury, but whether these assessments are relevant to future injury can be unclear.
The purpose of this study was to identify changes in strength, flexibility, range of motion, and alignment that may predict injury in the lower extremities of runners.
Data for the study was selected from data obtained from PubMed, Embase, CINAHL, and SPORTDiscus through May 2018.A prospective cohort study that analyzed musculoskeletal disorders associated with future running-related injuries was used as reference.
Two authors extracted the study data, assessed the methodological quality of each study using the Critical Appraisal Tool, and evaluated the overall quality using the GRADE approach.
The results showed that seven articles met the selection criteria and that the quality of evidence for the seven identified clinical appraisal change categories was very low.
One study described strong hip abductor muscles as significantly associated with running-related injuries, and increased hip external to internal rotational strength and decreased hip internal range of motion were each found to prevent running injuries in one study.
In one study, a decrease in navicular bone loss in women may prevent running-related injuries.
These, combined with the poor quality of evidence in the conclusions, show that lower extremity flexibility and muscle strength do not consistently prevent injury.
Discussion
The following is a description of what the views were on each of the assessment items.
Muscular strength of the hips
Evidence on periprosthetic muscle strength and injury prevention is of very low quality.
One study found an association between injured runners and those with low muscle strength in the hips, but other studies have not found such significant results.
Some studies also reported an association between increased strength of muscles related to hip external and internal rotation and injury prevention.
Range of motion of the hip joint
Evidence on hip range of motion is of very low quality.
Two studies looked at the mobility of external internal rotation of the hip during exercise and the suggestion that increased range of motion may be protective against fatigue fractures of the tibia.
Axis of the hip joint
The evidence on hip joint alignment is of very low quality.
Two studies looked at Q-angle and leg length, and as a result failed to find a significant relationship between alignment tests and RRI.
Hip Flexibility
The evidence on hip flexibility was also of very low quality.
One study investigated it with the straight leg raise test, but did not find a significant relationship between the straight leg raise test and RRI.
Strength around the knee
Evidence on muscle strength around the knee was also of very low quality.
One study used the HHD to investigate knee strength, but did not find a significant association between quadriceps strength or hamstring strength and RRI.
Ankle axis
Evidence for ankle alignment was of very low quality.
Three studies investigated navicular depression and its relationship to injury.
One study found a significant protective relationship between navicular shaft misalignment and injury in women.
Two studies found no significant relationship between navicular depression and injured runners.
One study looked at the axis of the foot and found no significant relationship between the axis of the foot and injured runners.
Range of motion of the ankle joint
Evidence on ankle range of motion was of very low quality.
One study examined ankle dorsiflexion range of motion and did not report a significant association between ankle dorsiflexion range of motion and RRI.
Christopher SM, McCullough J, Snodgrass SJ, Cook C. Do alterations in muscle strength, flexibility, range of motion, and alignment predict lower extremity injury in runners: a systematic review. Arch Physiother. 2019;9:2. Published 2019 Feb 12. doi:10.1186/s40945-019-0054-7
Conclusion
The results of this study suggest that there is a low relationship between lower extremity conditions and running injury prevention.
When I saw these results, I reflected on the bias in what I had been told and learned, although I cannot say for sure due to the heterogeneity of the data.
When an injury occurs, many things are expected, but most of them refer only to the movements that occur when the injury occurs.
From there, there are many ifs and buts about range of motion and muscle strength problems.
I think it's okay to have such a theory, but I would like to see a reasoned explanation as to why it would be preventive, since there is a reality that it is being used to unnecessarily inflame anxiety and take advantage of people who are worried. I would like to see a reasoned explanation as to why this is a preventive measure.
The results of this study suggest that the injury may be related to the hip abductor muscles, excessive range of motion of hip internal rotation, and depression of the navicular bone, one of the tarsal bones. However, it is not possible to say for sure due to the low quality.
It may be helpful, and I hope it is.
