Electromyographic activity of the lumbar and hip extensors during dynamic trunk extension exercise.
OBJECTIVE
To evaluate the effects of exercise intensity and multiple sets on muscle activation patterns during trunk extension exercise.


METHODS
Descriptive, repeated measures.


METHODS
University-based musculoskeletal research laboratory.


METHODS
Twenty volunteers recruited from a university setting.


METHODS
Not applicable.


METHODS
Electromyographic activity was recorded from the L3-4 paraspinal region, gluteus maximus, and biceps femoris muscles during multiple sets of trunk extension exercise at intensities representing 40%, 50%, and 70% of peak isometric force.


RESULTS
As exercise intensity increased, the electromyographic activity of the gluteus maximus increased to a greater extent than the activity of the paraspinal region. At the 50% intensity level, biceps femoris electromyographic activity was significantly greater than the paraspinal region electromyographic activity, whereas at the 70% intensity no differences were found between muscles. During multiple sets of exercise at the same intensity a muscle by set interaction was observed. This interaction revealed that with respect to other muscle groups, the electromyographic activity of the gluteus maximus increased between sets 1 and 2, whereas electromyographic decrements occurred in the paraspinal region. During exercise at the 40% intensity level, biceps femoris electromyographic activity increased to a greater extent between sets 1 and 2 when compared with the paraspinal region.


CONCLUSIONS
Exercise intensity and multiple sets result in alterations in muscle recruitment patterns of the lumbar and hip extensor muscles. These findings raise questions as to the efficacy of added loading and multiple sets during trunk extension exercise.
Clark
Brian C
BC
Musculoskeletal Research Laboratory, Department of Exercise Science, Syracuse University, 820 Comstock Avenue, Room 201, Syracuse, NY 13244, USA. bcclar01@syr.edu
Manini
Todd M
TM
Mayer
John M
JM
Ploutz-Snyder
Lori L
LL
Graves
James E
JE
D000328:Adult; D001415:Back / Q000502:physiology*; D002081:Buttocks / Q000502:physiology; D004576:Electromyography; D015444:Exercise / Q000502:physiology*; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D006615:Hip / Q000502:physiology*; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D017116:Low Back Pain / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control; D008161:Lumbosacral Region / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D013848:Thigh / Q000502:physiology; D016474:Weight-Bearing