Youth Running: A Maturation Study
Running is popular in youth today. This is great for their health & well-being. However, they also often experience injuries.
There is VERY little research in this group, making it difficult to prevent or treat these injuries. Could physical changes during puberty influence these injuries?
That is what we want to find out!
Physical activity in youth is necessary to reduce obesity and improve long-term health. However, injuries, especially those early on in life, can cause a reduction in physical activity. Running is a popular form of physical activity that is accessible to everyone because it is cheap and requires little equipment. The drawback of running is that many, if not most, runners will experience a running-related injury at some point in their life. In youth, these injuries are thought to occur with the physical maturation changes during puberty. However, no research study has previously investigated changes in running biomechanics (i.e. form) over the stages of puberty. This project will hopefully inform future research in youth runners for years to come. This study will include 150 physically active youth who will perform tests of running biomechanics, squatting biomechanics, muscle function (i.e. strength, endurance), and flexibility. We will analyze the differences in these tests between sexes and among stages of puberty (pre-pubertal, pubertal, post-pubertal).
Youth Participation in Sports
Participation in youth sports is vital to improving health both in the short and long term, especially as youth obesity increases nationally. The National Federation of Youth Sports reported that during the 2014-2015 school year 7,807,047 high school students participated in organized sports. For both girls and boys, running-related sports (i.e. cross country, track and field) are quite popular. In boys, track and field (#2) and cross country (#7) contribute over 1.25 million of these participants. Similarly, over 750,000 girls participated in track and field (#1) and cross country (#6). Running is a popular recreation sport in the US, with over 17 million people running in races annually. In youth, running is also extremely popular. Youth ages 6-17 years old make up 10% of all participants in running events across the U.S., resulting in 1.7 million participants.(USA Running 2016) Races marketed towards kids have grown substantially in the last few years, demonstrating the demand for youth running competition. Running provides improved physical and mental health; however, it is also associated with a substantial risk of musculoskeletal injury in both youth and adults.
Youth Overuse Injuries
Overuse injuries account for more than 50% of total sports injuries. (van Gent et al 2007) In high school runners, the overuse injury lifetime prevalence rates were reported to be 59% to 68%. (Tenforde, Sayres et al. 2011) Once injured, runners are more likely to sustain a re-injury, (van Gent, Siem et al. 2007) which increases the risk of reduced physical activity and subsequent disease later on in life. Understanding injury in this youth population, in hopes of later developing prevention programs, is therefore vitally important to maintaining physical activity and health later in life. Currently there is very little running research performed in youth population. We were unable to find studies comparing running mechanics (i.e. running form) between sexes in a youth population, nor were we able to identify any studies that compared running mechanics across different ages or stages of maturation. Stage of maturation has become an important aspect of injury prevention in the anterior cruciate ligament (ACL) rupture literature, suggesting that understanding maturation is important to injury prevention. (DiStefano, Martinez et al. 2015) However, these studies were not specifically performed with running tasks, possibly reducing their external validity and applicability to a different population, like runners. We aim to fill this large gap in the literature with the results of this study.
Biomechanics & Running Injury
Running biomechanics is a technical word for running form. A running biomechanical analysis gives researchers millions of data points that can be used to study human movement in depth. Using these analyses, there is very good research evidence that runners who have poor form are at a greater risk for injury. Runners who have excessive or limited motion at their ankle, knee, hips and pelvis seem to have more injuries than those who do not. For example, the knees buckling inward (i.e. valgus), is caused by excessive motion at the hips and is a risk factor for many injuries in adults. Two prospective studies (Noehren, Davis et al. 2007, Noehren, Hamill et al. 2013) in adults reported increased hip adduction (i.e. bringing thighs together) angles in those who developed chronic knee injuries compared to healthy control groups. In youth, one study (Myer, Ford et al. 2010) reported differences in knee forces during landing in a group of middle- and high-school female basketball athletes who would later suffer from chronic knee pain. Changes in maturation, specifically the transition through puberty, seem to influence injury risk during landing from a jump. However, we do not know if changes in maturation cause youth to develop errors in running form, which lead to injury. Before we can investigate injury, we must understand the normal maturation process and where the changes in running form naturally occur. A better understanding of this will allow us to improve planning for research studies that investigate injury.
Muscle Function & Running Injury
Muscle strength can influence the biomechanics of running, with weaker muscles leading to poor form and possibly increased injury. Research has demonstrated that those who have knee pain also have weak hips(Rathleff, Rathleff et al. 2014) To continue the example, weakness of the hips can cause increase hip adduction, which leads to the knees buckling during running. It is thought that this leads to injury. This same link from hip weakness to injury has not been made. One study (Rathleff, Baird et al. 2013) reported that there were no differences between youth (12-15 years old) with knee pain compared to those without. This group of youth were likely in the stage of puberty, though it was not measured, and the transition out of puberty to could influence risk of injury. One study (DiStefano, Martinez et al. 2015) has reported that those individuals who have progressed out of puberty (post-pubertal stage) have greater weakness than those are in pre-pubertal or pubertal stages. Our study would be able to confirm or deny these findings to further inform and better plan future studies.
Another measure of muscle function is muscle endurance. Some researchers (Souza and Powers 2009) have hypothesized that muscle endurance, instead of strength, is important for injury. One study (Bazett-Jones 2013) reported no differences when comparing hip and trunk endurance between those with chronic knee pain and those without. However, no studies have investigated whether maturation could influence muscular endurance. This study would be the first to tell us if stage of maturation influences muscular endurance.
Flexibility & Running Injury
Flexibility is often thought to influence injury but the evidence towards this line of argument is not strong. Some studies have reported that runners with excessive motion at their ankle are at greater risk for injury, (Warren and Jones 1987, Messier and Pittala 1988) and still others report that those with limited motion are the ones who are risk for injury. (Montgomery, Nelson et al. 1989) A previous study (DiStefano, Martinez et al. 2015)on the influence of maturation on flexibility demonstrated that post-pubescent girls showed limited ankle flexibility, which may make them more at risk for injury. Limited flexibility of the hip flexors and iliotibial band have also been cited by clinicians to influence injury in runners; however, limited data exists to show this is true. Also, no study has yet investigated whether flexibility of the hip flexors and iliotibial band changes with maturation. This study will help to answer this preliminary question regarding flexibility and maturation.