Background: Distance running is a popular interscholastic sport, but also has an associated high risk of running-related injuries. Recent literature suggests that functional tests may help to identify athletes at increased risk of injury. The Y-Balance Test (YBT) is an objective measure used to assess functional muscle strength and balance and to expose asymmetries between tested limbs. Purpose: To determine if YBT performance was associated with maturation status in healthy, youth distance runners. We hypothesized that mid-pubertal (MP) runners would demonstrate less functional reach distance than pre-pubertal (PrP) or post-pubertal (PoP) runners. Methods: A convenience sample of 142 (Females: n=79, Males: n=63) uninjured youth runners (ages 13.5±2.7 years; weekly running distance: 18.2±20.4 km) were recruited from the local community. All runners met inclusion criteria, indicating that they were between 9 and 19 years old and participated in long-distance running activities such as school/club track and field, cross country, road races, trail running, and/or soccer. The runners completed a modified Pubertal Maturational Observation Scale (PMOS), then were screened for right (R) and left (L) anterior (ANT), posteromedial (PM) and posterolateral (PL) reach distances (cm) normalized by lower limb length (cm). Composite reach distance was calculated by the sum of the three reach distances divided by three times the limb length multiplied by 100 for R and L limbs. ANOVA with Bonferroni post hoc tests were used to compare maximum normalized reach distances for the three directions and composite reach distance by maturation status and sex. Results: Overall, 31.7% were classified as PrP status, 26.1% as MP, and 42.3% as PoP, with similar percentages by sex ( p=0.84). The only significant mean difference was found for R ANT maximum normalized reach distance between PrP and PoP ( p=0.02), indicating a greater normalized reach in PrP athletes. No significant mean differences were found for R or L PM and PL maximum normalized reach distances, or for R or L composite reach distances, by maturation status or when stratified by maturation and sex ( p>0.05). Conclusions: In this sample of youth runners, the YBT was only a discriminator of anterior reach distance between pre-pubertal and post-pubertal runners. As decreased anterior reach is associated with reduced quadriceps muscle strength and anterior knee pain, reduced anterior reach in post-pubertal runners may potentially signify an increased risk of sustaining a running-related injury. Thus, preventive efforts to ensure good functional quadriceps muscle strength may be merited.
Quadriceps muscle strength, radiographic knee osteoarthritis and knee pain: the ROAD study
