Effects of reducing resistance, repetitions, and frequency of back-strengthening exercise in healthy young women: a pilot study.
OBJECTIVE
To determine the effects of reducing intensity or frequency of back-strengthening exercise on back extensor strength.


METHODS
Randomized controlled trial.


METHODS
Exercises were performed in participants' homes. Instruction and measurements were performed at the rehabilitation center in the hospital.


METHODS
Fifty-eight healthy female volunteers (mean age, 20 y).


METHODS
Participants were assigned to 1 of 5 exercise intervention groups: control; standard protocol (STD) that has been shown to increase back extensor strength; weight reduction (WRD); repetition reduction (RRD); and frequency reduction (FRD). Back exercises involved lifting a weighted backpack while in a prone position. The study period was 12 weeks.


METHODS
Isometric back extensor strength.


RESULTS
Back extensor strength increased significantly in all groups except the control group. The maximum increase was achieved by the STD group (39%), followed by the FRD (25%), WRD (22%), RRD (20%), and control (5%) groups. Percentage change in back extensor strength was significantly greater in the STD group than in all other groups except the FRD group.


CONCLUSIONS
Back extensor strength in the WRD, RRD, and FRD groups was significantly higher at 12 weeks compared with baseline. Reductions in intensity and frequency resulted in similar effects on increases in back extensor strength.
Department of Orthopedic Surgery, Akita University School of Medicine, Akita, Japan. mhongo@doc.med.akita-u.ac.jp
Michio
M
Hongo
Eiji
E
Itoi
Mehrsheed
M
Sinaki
Yoichi
Y
Shimada
Naohisa
N
Miyakoshi
Kyoji
K
Okada
D000293:Adolescent; D000328:Adult; D001415:Back / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D010865:Pilot Projects; D014891:Weight Lifting / Q000502:physiology*