Diurnal Variation of Hamstring and Lumbar Flexibility

Abstract

2409 Past studies have demonstrated that lumbar range of motion varies with time of day, with spinal flexion exhibiting the greatest variation. Research suggests variability in spinal flexion effects sport performance, activities of daily living, and occupational injury prevention. Previous studies of spinal flexion have not assessed the daily variation of hamstring flexibility nor the differences between male and female flexibility. PURPOSE: To compare diurnal variation of hamstring muscles and lumbar spine during flexion and to determine if there are any diurnal flexibility differences between males and females. METHODS: 67 healthy college students (F = 36 and M = 31; age = 22 ± 3 yrs) were recruited. Subjects had regularly exercised at least 3 times a week for the last year and averaged 6–8 hours of sleep per night for the last month. Using the active knee extension test (AKE) and modified modified Schober test (MMS) hamstring and lumbar flexibility measurements were taken at waking and every 2 hours through a 12 hour period. Exercise or vigorous activity was not permitted and physical activities (PA) were standardize into METs using the Ainsworth's Compendium of Physical Activity and Exercise from subject diaries. RESULTS: Hamstring flexibility was lowest at waking (Females −47.7 ± 15.58°, Males −53.1 ± 12.8°) and highest at the end of 12 hours (Females −37.4 ± 17.49°, Males −48.6 ± 14.9°). Lumbar flexion exhibited a similar pattern with lowest flexibility at waking (Females 6.0 ± 1.4 cm, Males 6.9 ± 1.3 cm) and highest flexibility during the 10th hour after waking (Females 6.9 ± 1.2 cm, Males 7.5 ± 0.9 cm). Females were significantly more flexible at every time period than males (p < 0.05) but both sexes experienced a similar pattern of increase in range of motion for hamstrings and lumbar spine over 12 hours. Minimum PA was at waking (Females and Males 0.9 ± 0.0 METs) while peak PA was during the 10th hour after waking (Females 1.6 ± 0.9 METs, Males 1.5 ± 0.6). While there was a statistically significant increase in PA from waking to 2 hours after waking for both sexes (Females waking 0.9 ± 0.0, waking+ 2hrs 1.4 ± 0.4 METs; Males waking 0.9 ± 0.0, waking+ 2 hrs 1.2 ± 0.3 METs) PA remained unchanged through the remaining 10 hours. PA was not significantly different between males and females. CONCLUSIONS: Hamstring and lumbar flexibility demonstrated a similar pattern during a day of normal activity for both sexes. Further study is needed to determine if different physical activity levels alters the observed pattern, and how this pattern affects performance and injury risk. Results from this study may help design flexibility programs that help optimize performance and reduce injury.