Objective: To determine whether adolescent growth is associated with a decrease in flexibility.
Design: Longitudinal cohort study of urban high school students.
Main outcome measures: Flexibility of hamstring muscles (popliteal angle), quadriceps muscles (quadriceps angle), lumbar extensor muscles (Schober test), and combined lower extremity-trunk muscles (Sit and Reach test).
Results: There was no relation between growth and changes in flexibility for the lumbar flexor muscles, hamstring muscles, or muscles involved in the Sit and Reach test. Although there was a slight decrease in flexibility of the quadriceps muscle with increases in growth, the very low r2adj value (0.01-0.06) strongly suggests that growth plays only a small role in determining the flexibility of individuals.
Conclusion: These results strongly suggest that growth is not a cause of decreased flexibility during the peripubescent period.