The differential effects of PNF versus passive stretch conditioning on neuromuscular performance

Abstract

The effects of flexibility conditioning on neuromuscular and sensorimotor performance were assessed near to full knee extension (25°). Eighteen males who were randomly assigned into two groups underwent eight weeks (three-times per week) of flexibility conditioning (hip region/knee flexor musculature; dominant limb) involving either proprioceptive neuromuscular facilitation (PNF) (n=9) or passive stretching (PASS) (n=9). Both modes of flexibility conditioning are popular within contemporary exercise and clinical settings and have demonstrated efficacy in improving range of motion. The contralateral limb and a prior 'no exercise' condition were used as controls. The PNF and PASS modes of conditioning improved passive hip flexibility to a similar extent (mean 19.3% vs. baseline, intervention limb, p<0.01) but did not alter knee flexor strength (overall mean 309.6±81 N) or sensorimotor performance (force and positional errors: 2.3±8.2% and 0.48±7.1%). Voluntary and magnetically evoked electromechanical delays (EMDV and EMDE, respectively) were increased but to a greater extent following PASS compared to PNF (PASS: 10.8% and 16.9% lengthening of EMDV and EMDE, respectively vs. PNF: 3.2% and 6.2%, p<0.01).The attenuated change to electromechanical delay (EMD) performance during PNF conditioning suggests a preserved capability for rapid muscle activation, which is important in the maintenance of dynamic joint stability. That PNF was also equally efficacious in flexibility conditioning would suggest that this mode of flexibility training should be used over passive to help preserve dynamic joint stability capabilities at this extended and vulnerable joint position.

Positive Effects of Proprioceptive Neuromuscular Facilitation Stretching on Sports Performance: A Review

“…A 6 weeks (5 days a week x 30s) PNF stretching training also didn't cause a change on passive resistive torque (Konrad, Gad & Tilp 2015). Minshull et al (2014) also received similar results in his study in which similar protocols used (8 weeks, 3 days a week) Higgs and Winter (2009) could not find any evidence showing that PNF training (4 weeks, 3 times a week) is harmful to isokinetic torque generation. This study indicated that increasing flexibility does not have a negative effect on isokinetic torque.…”

“…Acute effects were studied in 4 of these studies and chronic effects in 4 of them. There were positive effects in 2 of the studies (Handel et al 1997, Rees et al 2007, null effect in 6 of them (Young & Elliott 2001, Manoel et al 2008, Place et al 2013, Reis et al 2013, Minshull et al 2014, Konrad, Gad & Tilp 2015, (Table 2). …”

Immediate Effects of Proprioceptive Neuromuscular Facilitation Stretching Programs Compared With Passive Stretching Programs for Hamstring Flexibility: A Critically Appraised Topic

“…Four studies used an isometric hamstring contraction for the contract-relax PNF. [6][7][8][9] In contrast the fifth study Davis et al, 5 had the subject contract their quadriceps instead of the hamstrings, however the remainder of their stretching protocol stayed consistent to the other studies. For static stretching, 2 studies 5,6 directed their subjects to perform unassisted static stretching while other studies completed the static stretching protocol with the assistance of a clinician.…”

Immediate Effects of Stretching for Iliopsoas Muscles on Lumbopelvic-Hip Kinematics during Gait: A Randomised Controlled Trial Using Subjects with Non-Specific Low Back Pain

“…The study by Kerrigan, et al used four sets of 30-second stretches, whilst the stretching maneuver in this study was held for 20 s. Therefore, further study with more vigorous stretching techniques is required. Although exploring the effects of passive stretching techniques might be also helpful [21], the reliability of measuring methods stretching method to improve hip extension and control lumbopelvic movements of patients with non-specific low back pain, which is exacerbated by extension-related activities.…”