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A Comparison of Single vs. Repeated MVIC Maneuvers Used in PNF Flexibility Techniques for Improvement in ROM.

Cornelius, William L.; Hayes, Karen K.
Journal of Strength & Conditioning Research: November 1987
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Several studies have focused on various modified proprioceptive neuromuscular facilitation (PNF) techniques in improving hip joint range of motion (ROM). There appears to be, however, confusion as to how many maximum voluntary isometric contraction (MVIC) maneuvers are necessary per trial to increase ROM. This study compared a single MVIC manuver to repeated MVIC maneuvers in increaing flexibility of the hip joint. Thirty female subjects, ages 25 to 31, were randomly assigned to one of two treatment groups. Each subject was measured prior to the treatment to establish a baseline measurement from which to gauge the subject's hip flexion improvement. Both groups utilized a hold-relax PNF treatment. Group 1 received a hold-relax PNF treatment incorporating a single six-second isometric contraction (1-6HR) of the hip extensors. The 1-6 HR PNF maneuver used a passive pre-stretch follwed by a six-second isometric contraction and subsequent passive stretch. Group 2 used a hold-relax PNF treatment with three consecutive six-second isometric contractions (3-6 HR). The 3-6 HR PNF maneuver began with a passive pre-stretch followed by three consecutive six-second isometric contractions, each followed by a passive stretch to a new tension point. A measurement was taken after the third contraction and subsequent passive stretch. The two stretching conditions involved the hip extensors of the preferred leg for both the passive stretch and isometric contraction. A two (PNF conditon) by four (trials) ANOV A research design was used. An average for the trials was significantly higher (p<.05) than the baseline. However, there was no significant difference between the two PNF treatments in increasing hip joint ROM. These findings appear to suggest that multiple MVIC maneuvers do not provide an advantage over the use of a single MVIC maneuver in the hold-relax PNF technique for increasing acute ROM.

(C) 1987 National Strength and Conditioning Association