title: The efficacy of two modified proprioceptive neuromuscular facilitation stretching techniques in subjects with reduced hamstring muscle length.
abstract: Difference scores in knee extension angle and electromyographic (EMG) activity were quantified before and after modified proprioceptive neuromuscular facilitation (PNF) hold-relax (HR) and hold-relax-antagonist contraction (HR-AC) stretching procedures in 35 healthy individuals with reduced hamstring muscle length bilaterally (knee extension angle <160 degrees ). Participants were randomly assigned each PNF procedure to opposite lower extremities. Knee extension values were measured by using a goniometer. EMG data were collected for 10 seconds before and immediately after each PNF stretching technique and normalized to maximum voluntary isometric contraction (% MVIC). A significant time by stretch-type interaction was detected (F(1,34) = 21.1; p < 0.001). Angles of knee extension for HR and HR-AC were not different prior to stretching (p = 0.45). Poststretch knee extension angle was greater in the HR-AC condition than the HR condition (p < 0.007). The proportion of subjects who exceeded the minimal detectable change (MDC(95)) with the HR-AC stretch (97%) did not differ (p = 0.07) from the proportion who exceeded the MDC(95) with the HR stretch (80%). Because EMG activation increased (p < 0.013) after the HR-AC procedure, it is doubtful a relationship exists between range of motion improvement after stretching and inhibition of the hamstrings. On average the 10-second modified HR procedure produced an 11 degrees gain in knee extension angle within a single stretch session.
authors.affiliation: Mayo Clinic, Rochester, Minnesota 55905, USA. youdas.james@mayo.edu
authors.forename: James W
authors.initials: JW
authors.lastname: Youdas
authors.forename: Kristin M
authors.initials: KM
authors.lastname: Haeflinger
authors.forename: Melissa K
authors.initials: MK
authors.lastname: Kreun
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Holloway
authors.forename: Christine M
authors.initials: CM
authors.lastname: Kramer
authors.forename: John H
authors.initials: JH
authors.lastname: Hollman
mesh_terms: D000328:Adult; D004576:Electromyography; D056228:Feedback, Sensory; D005260:Female; D006801:Humans; D007717:Knee; D008297:Male; D052580:Muscle Stretching Exercises / Q000379:methods*; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000502:physiology*; D016059:Range of Motion, Articular; D055815:Young Adult