title: Effects of load on good morning kinematics and EMG activity.
abstract: Many strength and conditioning coaches utilize the good morning (GM) to strengthen the hamstrings and spinal erectors. However, little research exists on its electromyography (EMG) activity and kinematics, and how these variables change as a function of load. The purpose of this investigation was to examine how estimated hamstring length, integrated EMG (IEMG) activity of the hamstrings and spinal erectors, and kinematics of the lumbar spine, hip, knee, and ankle are affected by changes in load. Fifteen trained male participants (age = 24.6 ± 5.3 years; body mass = 84.7 ± 11.3 kg; height = 180.9 ± 6.8 cm) were recruited for this study. Participants performed five sets of the GM, utilizing 50, 60, 70, 80, and 90% of one-repetition maximum (1RM) in a randomized fashion. IEMG activity of hamstrings and spinal erectors tended to increase with load. Knee flexion increased with load on all trials. Estimated hamstring length decreased with load. However, lumbar flexion, hip flexion, and plantar flexion experienced no remarkable changes between trials. These data provide insight as to how changing the load of the GM affects EMG activity, kinematic variables, and estimated hamstring length. Implications for hamstring injury prevention are discussed. More research is needed for further insight as to how load affects EMG activity and kinematics of other exercises.
authors: Kinesiology Program, School of Nutrition and Health Promotion, College of Health Solutions, Arizona State University , Phoenix, AZ , USA.
authors: Andrew David
authors: AD
authors: Vigotsky
authors: Kinesiology Program, School of Nutrition and Health Promotion, College of Health Solutions, Arizona State University , Phoenix, AZ , USA.
authors: Erin Nicole
authors: EN
authors: Harper
authors: Kinesiology Program, School of Nutrition and Health Promotion, College of Health Solutions, Arizona State University , Phoenix, AZ , USA.
authors: David Russell
authors: DR
authors: Ryan
authors: School of Sport and Recreation, Auckland University of Technology , Auckland , New Zealand.
authors: Bret
authors: B
authors: Contreras
keywords: Hamstring length; Hamstring strain; Hamstrings; Injury prevention; Intensity of load
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