Effects of a Single Proprioceptive Neuromuscular Facilitation Stretching Exercise With and Without Post-stretching Activation on the Muscle Function and Mechanical Properties of the Plantar Flexor Muscles.

Marina Reiner,Markus Tilp,Andreas Konrad,Masatoshi Nakamura,Antonio Morales-Artacho,Gaël Guilhem

doi:10.3389/fphys.2021.732654

Abstract

A single proprioceptive neuromuscular facilitation (PNF) stretching exercise can increase the range of motion (ROM) of a joint but can lead to a decrease in performance immediately after the stretching exercise. Post-stretching activation (PSA) exercises are known as a possible way to counteract such a drop in performance following a single stretching exercise. However, to date, no study has investigated the combination of PNF stretching with PSA. Thus, the aim of this study was to compare the effects of a PNF stretching exercise with and without PSA on the muscle function (e.g., ROM) and mechanical properties of the plantar flexor muscles. Eighteen physically active males volunteered in the study, which had a crossover design and a random order. The passive shear modulus of the gastrocnemius medialis (GM) and gastrocnemius lateralis (GL) was measured in a neutral position with shear wave elastography, both pre- and post-intervention. Maximum voluntary isometric contraction (MVIC) peak torque, maximum voluntary dynamic contraction peak torque, dorsiflexion ROM, and passive resistive torque (PRT) were also measured with a dynamometer. The interventions were 4×30s of PNF stretching (5s of contraction) and two sets of three exercises with 20 or 40 fast ground contacts (PNF stretching+PSA) and PNF stretching only. ROM was found to have increased in both groups (+4%). In addition, the PNF stretching+PSA group showed a decrease in PRT at a given angle (−7%) and a decrease in GM and mean shear modulus (GM+GL; −6%). Moreover, the MVIC peak torque decreased (−4%) only in the PNF stretching group (without PSA). Therefore, we conclude that, if PNF stretching is used as a warm-up exercise, target-muscle-specific PSA should follow to keep the performance output at the same level while maintaining the benefit of a greater ROM.

Highlights

Stretching is a commonly used technique during a warm-up protocol
The SWE ICC values between the pre-measurements of both test days (PNF stretching vs. proprioceptive neuromuscular facilitation (PNF) stretching + Post-stretching activation (PSA)) for the gastrocnemius medialis (GM) and gastrocnemius lateralis (GL) were 0.77 and 0.89, respectively
Baseline characteristics for pre-measurements on both test days showed no significant difference in GM shear modulus (p = 0.28), GL shear modulus (p = 0.32), mean shear modulus of the GM + GL (p = 0.842), Maximum voluntary isometric contraction (MVIC) peak torque (p = 0.37), maximum voluntary dynamic contraction (MVDC) peak torque (p = 0.79), range of motion (ROM) (p = 0.87), passive resistive torque (PRT) (p = 0.56), and PRT at a given angle (p = 0.951)

Summary

Introduction

Stretching is a commonly used technique during a warm-up protocol. Several studies have compared different stretching techniques and suggested that proprioceptive neuromuscular facilitation (PNF) and static stretching (SS) can be effective for increasing the range of motion (ROM; Konrad et al, 2017; Lempke et al, 2018). Differences in the torqueangle curve of the PRT indicate a decrease in the soft tissue component of the muscle (e.g., muscle stiffness: Konrad et al, 2017; tendon stiffness: Kay et al, 2015) This mechanism is one possible explanation for the changes in ROM. Nakamura et al (2015) found a higher end ROM after PNF stretching and concomitant higher passive peak torque values at the maximal joint position. This finding indicates an increased tolerance to stretch (e.g., less pain sensitivity, Magnusson et al, 1996)

Objectives

Methods

Results

Discussion

Conclusion