Effect of sex hormones on neuromuscular control patterns during landing

• Published in: Journal of electromyography and kinesiology Vol. 18; no. 1; pp. 68 - 78
• Main Authors: Dedrick, Gregory S, Sizer, Phillip S, Merkle, Jennifer N, Hounshell, Troy R, Robert-McComb, Jacalyn J, Sawyer, Steven F, Brismée, Jean-Michel, Roger James, C
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-02-2008
• Subjects: ACL; Adult; Electromyography - methods; Electromyography - statistics & numerical data; Female; Gonadal Steroid Hormones - blood; Gonadal Steroid Hormones - physiology; Humans; Knee Joint - physiology; Knee valgus; Lower Extremity - physiology; Menstrual cycle; Menstrual Cycle - physiology; Motor Activity - physiology; Muscle Contraction - physiology; Muscle, Skeletal - physiology; Onset latency; Physical Medicine and Rehabilitation; Time Factors; Weight-Bearing; ACL; Onset latency; Knee valgus; Menstrual cycle
• ISSN: 1050-6411; 1873-5711
• DOI: 10.1016/j.jelekin.2006.09.004

Abstract The purpose of the study was to investigate the effects of sex hormones across menstrual cycle phases on lower extremity neuromuscular control patterns during the landing phase of a drop jump. A repeated-measures design was utilized to examine sex hormone effects in 26 recreationally active eumenorrheic women. Varus/valgus knee angle and EMG activity from six lower extremity muscles were recorded during three drop jumps from a 50 cm platform in each phase of the menstrual cycle. Blood assays verified sex hormone levels and cycle phase. The semitendinosus muscle exhibited onset delays ( p ⩽ 0.006) relative to ground contact during the luteal phase, and demonstrated a significant ( p ⩽ 0.05) difference between early and late follicular phases. Muscle timing differences between the gluteus maximus and semitendinosus were decreased ( p ⩽ 0.05) in the luteal compared to early follicular phases. These results suggest a different co-contractive behavior between the gluteus maximus and semitendinosus, signifying a shift in neuromuscular control patterns. It appears that female recreational athletes utilize a different neuromuscular control pattern for performing a drop jump sequence when estrogen levels are high (luteal phase) compared to when they are low (early follicular phase).