Acute effects of contract-relax (CR) stretch versus a modified CR technique

Stretching exercises in managing spasticity: effectiveness, risks, and adjunct therapies

Spasticity is a component of upper motor neuron disorders and can be seen in neurological conditions like stroke and multiple sclerosis. Although the incidence rate of spasticity is unknown, it can put pressure on the health condition of those with spasticity, and there is no absolute effective way to control it. In the past, stretching exercises were an accessible tool for physical therapists to manage and control spasticity, but opinions on the optimal dose, aftereffects, and mechanism of effects were controversial. Therefore, this article tries to provide an overview of the effectiveness and risks of stretching exercises. Furthermore, there are several adjunct therapies, such as brain stimulation and botulinum injection, that can increase the effectiveness of a simple stretch by increasing cortical excitability and reducing muscle tone and their role is evaluated in this regard. The results of this study propose that several prospective and case studies have demonstrated the benefits of stretching to control spasticity, but it seems that other methods such as casting can be more effective than a simple stretch. Therefore, it is better to use stretching in combination with other therapeutic regimes to increase its effectivity of it.

Effects of patterned electrical sensory nerve stimulation and static stretching on joint range of motion and passive torque

Static stretching and proprioceptive neuromuscular facilitation stretching techniques can modulate specific neural mechanisms to improve the range of motion. However, the effects of modulation of these neural pathways on changes in the range of motion with static stretching remain unclear. Patterned electrical stimulation of the sensory nerve induces plastic changes in reciprocal Ia inhibition. The present study examined the effects of patterned electrical stimulation and static stretching on a range of motion and passive torque in plantarflexion muscles. The subjects were 14 young men (age 20.8 ± 1.3 years). The effects of patterned electrical stimulation (10 pulses at 100 Hz every 1.5 s) or uniform electrical stimulation (one pulse every 150 ms) to the common peroneal nerve for 20 min on reciprocal Ia inhibition of the Hoffman reflex (H-reflex) were examined. Reciprocal Ia inhibition was evaluated as short-latency suppression of the soleus H-reflex by conditioning stimulation of the common peroneal nerve. Then, the effects of transcutaneous electrical nerve stimulation (patterned electrical stimulation or uniform electrical stimulation) or prolonged resting (without electrical stimulation) and static 3-min stretching on the maximal dorsiflexion angle and passive torque were investigated. The passive ankle dorsiflexion test was performed on an isokinetic dynamometer. Stretch tolerance and stiffness of the muscle-tendon unit were evaluated by the peak and slope of passive torques, respectively. Patterned electrical stimulation significantly increased reciprocal Ia inhibition of soleus H-reflex amplitude (9.7 ± 6.1%), but uniform electrical stimulation decreased it significantly (19.5 ± 8.8%). The maximal dorsiflexion angle was significantly changed by patterned electrical stimulation (4.0 ± 1.4°), uniform electrical stimulation (3.8 ± 2.3°), and stretching without electrical stimulation (2.1 ± 3.3°). The increase in stretch tolerance was significantly greater after patterned electrical stimulation and uniform electrical stimulation than after stretching without electrical stimulation. Stiffness of the muscle-tendon unit was significantly decreased by patterned electrical stimulation, uniform electrical stimulation, and stretching without electrical stimulation. Transcutaneous electrical nerve stimulation and static stretching improve stretch tolerance regardless of the degree of reciprocal Ia inhibition.

Acute Effects of Static and Proprioceptive Neuromuscular Facilitation Stretching of the Plantar Flexors on Ankle Range of Motion and Muscle-Tendon Behavior in Children with Spastic Cerebral Palsy-A Randomized Clinical Trial

Stretching is considered a clinically effective way to prevent muscle contracture development in children with spastic cerebral palsy (CP). Therefore, in this study, we assessed the effects of a single session of proprioceptive neuromuscular facilitation (PNF) or static stretching (SS) on ankle joint range of motion (RoM) and gastrocnemius muscle-tendon behavior in children with CP. During the SS (n = 8), the ankle joint was held in maximum dorsiflexion (30 s). During the PNF stretching (n = 10), an isometric contraction (3-5 s) was performed, followed by stretching (~25 s). Ten stretches were applied in total. We collected data via dynamometry, 3D motion capture, 2D ultrasound, and electromyography, before and after the stretching sessions. A mixed ANOVA was used for the statistical analysis. Both ankle RoM and maximum dorsiflexion increased over time (F(1,16) = 7.261, p < 0.05, η² = 0.312; and F(1,16) = 4.900, p < 0.05, η² = 0.234, respectively), without any difference between groups. An interaction effect (F(1,12) = 4.768, p = 0.05, η² = 0.284) was observed for muscle-tendon unit elongation (PNF: -8.8%; SS: +14.6%). These findings suggest a positive acute effect of stretching on ankle function. However, SS acutely increased muscle-tendon unit elongation, while this decreased after PNF stretching, indicating different effects on the spastic muscles. Whether PNF stretching has the potential to cause positive alterations in individuals with CP should be elucidated in future studies.

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

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.

PNF- based Gait Rehabilitation-training after a Total Hip Arthroplasty in congenital pelvic malformation; A case report

INTRODUCTION

Congenital dysplasia of the pelvis often occurs in isolation, however, it can also involve other pelvic components, and anomalies of the digestive system. Pelvic malformations have effects on the pelvic girdle and pelvic stability influencing the quality of gait. The condition can be treated with a total hip arthroplasty (THA). The concept of Proprioceptive Neuromuscular Facilitation (PNF) has been described as a comprehensive rehabilitation approach with a focus on motor learning. This case report seeks to illustrate the clinical reasoning and feasibility of applying the PNF-concept in a patient after a THA with multiple congenital pelvis malformations.

CASE DESCRIPTION

A male, 44 years of age, physically active laborer was treated with THA after hip dysplasia, with comorbid missing pubic symphysis. The patient presented with complaints in gait speed, gait distance, hip joint mobility and stability.

PATIENT MANAGEMENT

PNF-based motor-control training, including specified PNF-pattern exercises with specific PNF-facilitation principles and techniques was provided over a period of eighteen weeks. Results showed improvements beyond the minimal detectable change and/or the minimal clinically important difference for physical functioning in gait, strength, range of motion, and personal required activities.

DISCUSSION AND CONCLUSION

Gait rehabilitation training, restoring altered movement patterns in the patient's activities of daily living was provided with PNF. Besides targeting structural impairments, this approach elicited motor learning effects. PNF-patterns have been described as: "mimicking functional activities" from daily life and sports. A specified PNF-based therapy including motor learning components, was a feasible approach in this case of complex pelvic skeletal malformations.

Effects of Static Stretching With High-Intensity and Short-Duration or Low-Intensity and Long-Duration on Range of Motion and Muscle Stiffness

This study investigated the effects of static stretching (SS) delivered with the same load but using two protocols – high-intensity and short-duration and low-intensity and long-duration – on range of motion (ROM) and muscle stiffness. A total of 18 healthy students participated in the study. They randomly performed high-intensity and short-duration (120% and 100 s) or low-intensity and long-duration (50% and 240 s) SS. Outcomes were assessed on ROM, passive torque at dorsiflexion ROM, and shear elastic modulus of the medial gastrocnemius before and after static stretching. The results showed that ROM increased significantly at post-stretching compared to that at pre-stretching in both high-intensity and short-duration [+6.1° ± 4.6° (Δ25.7 ± 19.9%)] and low-intensity and long-duration [+3.6° ± 2.3° (Δ16.0 ± 11.8%)]. Also, the ROM was significantly higher at post-stretching in high-intensity and short-duration conditions than that in low-intensity and long-duration. The passive torque at dorsiflexion ROM was significantly increased in both high-intensity and short-duration [+5.8 ± 12.8 Nm (Δ22.9 ± 40.5%)] and low-intensity and long-duration [+2.1 ± 3.4 Nm (Δ6.9 ± 10.8%)] conditions, but no significant differences were observed between both conditions. The shear elastic modulus was significantly decreased in both high-intensity and short-duration [−8.8 ± 6.1 kPa (Δ − 38.8 ± 14.5%)] and low-intensity and long-duration [−8.0 ± 12.8 kPa (Δ − 22.2 ± 33.8%)] conditions. Moreover, the relative change in shear elastic modulus in the high-intensity and short-duration SS was significantly greater than that in low-intensity and long-duration SS. Our results suggest that a higher intensity of the static stretching should be conducted to increase ROM and decrease muscle stiffness, even for a short time.

The external validity of a novel contract-relax stretching technique on knee flexor range of motion

Introduction

Compromised joint range of motion (ROM) can negatively affect the capacity to perform activities of daily living in clinical populations. Recently, similar improvements in dorsiflexion ROM were reported following dynamometry‐based contract‐relax (CR) stretching and modified CR stretching technique (stretch‐return‐contract [SRC]) where the contraction phase was performed “off stretch.” As neither the impact of SRC on other muscle groups nor the ecological validity of SRC performed in an applied environment has been tested, the acute effects of both techniques in dynamometry‐ (CR_dyna and SRC_dyna) and field‐based (CR_field and SRC_field) environments were compared with the hamstring muscle group.

Methods

Seventeen participants performed each of the four stretching conditions on separate days in a randomized order. Before and after the stretches, knee extension ROM and passive knee flexor moment were recorded on an isokinetic dynamometer.

Results

Significant (P < .01) increases in knee extension ROM (4.6‐5.2°) and elastic potential energy storage (12.0%‐23.6%) and decreases in the slope of the passive moment‐angle relation (8.9%‐12.2%) occurred in all conditions. Significant increases in peak passive joint moment were observed after field‐ (14.3%‐14.8%) but not dynamometry‐based (4.6%‐6.6%) stretches. No difference (P > .05) in any measure was found between conditions.

Conclusions

These data confirm the acute efficacy of the SRC technique in the hamstring muscle group and demonstrate its ecological validity in an applied environment in healthy participants. As the field‐based SRC technique was performed without partner assistance, when compared with classical PNF it represents an equally effective and practical stretching paradigm to support athletic and clinical exercise prescription.

The effects of different durations of static stretching within a comprehensive warm-up on voluntary and evoked contractile properties

Evidence for performance decrements following prolonged static stretching (SS) has led to a paradigm shift in stretching routines within a warm-up. Rather than SS, dynamic stretching (DS) and dynamic activity (DA) have replaced SS within warm-up routines. The objective of the present study was to compare the effect of differing lower limb SS durations (30 [SS30s], 60 [SS60s] or 120 s [SS120s] of SS per muscle group or no-stretch control) within a comprehensive warm-up protocol consisting of aerobic activity, DS and DA. Sixteen male participants completed the four stretching conditions in a randomized order, after a 5-min low-intensity (cycle) warm-up and before a DS/DA component on separate days. Tests included passive hip and knee ranges of motion (ROM), maximum voluntary knee extensor/flexor force, force produced at 100 ms (F100), vertical jump height and evoked knee extensor contractile properties. For hip flexion (hamstrings) ROM, SS120s provided the largest increase (5.6-11.7%) followed by SS60s (4.3-11.4%), control (4.4-10.6%) and SS30s (3.6-11.1%). For knee flexion (quadriceps) ROM, SS30s provided the largest increase (9.3-18.2%) followed by SS120s (6.5-16.3%), SS60s (7.2-15.2%) and control (6.3-15.2%). There were decreases in quadriceps F100 following SS in SS120s (29.6%) only. There were increases in vertical jump performance in the control (6.2%), SS60s (4.6%) and SS30s (3.3%). While 120 s SS per muscle increased ROM, even within a comprehensive warm-up routine, it also elicited notable performance decrements. However, moderate durations of SS were observed to improve ROM whilst either having negligible or beneficial (but not detrimental) effects on specific aspects of athletic performance.

Efficacy of proprioceptive neuromuscular facilitation compared to other stretching modalities in range of motion gain in young healthy adults: A systematic review

The objective of this study was to evaluate the efficacy of proprioceptive neuromuscular facilitation (PNF) on range of motion (ROM) gain in young healthy adults. We performed a systematic review of randomized controlled trials and quasi-randomized trials, including young healthy adults. The interventions were: PNF compared with different PNF techniques, control, other muscle stretching exercises and musculoskeletal manipulations. The outcome measures were: articular ROM and adverse effects. The final number of included studies was 46, involving 1,864 adults. There was difference on ROM comparing assisted hold-relax (HR) on diagonal plane to control, based on very low-quality evidence. There was also difference on ROM comparing assisted HR to self-HR; self-contract-relax (CR) to control; assisted CR contract to control; and assisted HR contract to control, based on low-quality evidence. Moderate-quality evidence shows that results differ between self HR and control (SMD: 0.95; 95%CI 0.03, 1.86; I²49%; P = 0.16) in terms of ROM gain. When performing the other comparisons, the results were based on low or very low-quality evidence and do not allow to state if PNF is more or less effective than other stretches for improving ROM in healthy young adults. No adverse effects were mentioned.