TITLE: Acute effects of neural mobilization and infrared on the mechanics of the
median nerve

  ABSTRACT:
[Purpose] This study analyzed the acute effects of infrared and neural mobilization on
the median nerve on the range of elbow extension of the dominant limb. [Subjects and
Methods] Forty participants from university, neurologically asymptomatic, 12 males and 28
females (22.8 ± 1.9 years), were randomly divided into four groups: Group 1 (control)
rested for 25 minutes in the supine position; Group 2 received the specific neural
mobilization for the median nerve; Group 3 received an application of infrared for 15
minutes on the forearm; Group 4 received the same application of infrared followed by
neural mobilization. The goniometric parameters of elbow extension were evaluated after
the intervention. [Results] Significant differences of extension value were observed
between Group 1 and Group 3 (15.75 degrees), and between Group 1 and Group 4 (14.60
degrees), and the average higher in Group 3 (26.35 degrees). [Conclusion] This research
provides new experimental evidence that NM in relation to superficial heat produces an
immediate effect on elbow range of motion versus NM isolated.

BODY.INTRODUCTION:
Functionality depends on tangible aspects as well as personal and environmental factors.
One of its components is human movement which needs undamaged body structures for its proper
functioning1). During daily activities,
the human body experiences mechanical stresses that are distributed in order to prevent
injuries and dysfunction. This force transfer is partially a consequence of the structure of
the nervous system2, 3), and it can be evaluated through neurodynamic tests that analyze,
based on anatomy, the mobility of specific nerves for being designed in a controlled
position of the member4, 5). Nervous system movement disabilities or / and elasticity
may compromise the homeostasis of neurodynamics and result in Adverse Neural Tension (ANT),
a term used to explain how pathology affects the normal movement and biomechanics of the
nervous system and its surrounding tissues6).  Techniques that restore nerve mobility that has restricted longitudinal movement are often
called neural mobilization techniques. Neural Mobilization (NM) includes manual therapy
techniques (gliding and stretching) that have been shown to decrease disability and
hypoalgesia when used as a treatment for various musculoskeletal and neural disorders. When
neural mobilization is used to treat adverse neural tension, the primary objective is to
restore the movement and the elasticity of the peripheral nervous system, besides promoting
a return of normal function7, 8), and amelioration of the symptomatic condition. Neural
mobilization studies have been reported to be effective at reinstating functionality9, 10),
but to the best of our knowledge no study has investigated NM in association with
hyperthermia provided by infrared (IR), a modality often used in clinical practice for
muscle relaxation11, 12), pain reduction and repair promotion of soft tissue injuries13). Infrared acts on collagen and decreases
tissue resistance12, 14). Moreover, heat promoted by neurotendineous sensitivity reduces
muscle tension reduction15), tiredness and
muscle pain and it also limits blood flow and prevents the removal of metabolites16). Some factors such as connective tissue
extensibility influence the magnitude of body motion17), and this insufficient median nerve mobility compromises elbow
extension18). It thought that IR might
enhance NM effects, thereby increasing the amplitude elbow extension. Thus, this study
analyzed the acute effects of superficial heat and neural mobilization of the median nerve
on the range of elbow extension of the dominant limb.

BODY.SUBJECTS AND METHODS:
A randomized controlled clinical trial was carried out at the Federal University of Piauí
Physiotherapy Clinical School. The subjects were 40 students, 12 males and 28 females
(average age 22.8 ± 1.9 years), from the university who had no neurological diseases.
Subjects were excluded if they had limited passive range of movement of the upper body. All
participants were aware of the aims of this study before participating in the study, which
was approved by the University of Piauí Committee Research Ethics −838854 / 2014.  The participants were randomly divided into four groups of ten subjects: G1 (control
group), G2 (neural mobilization group), G3 (infrared group), and G4 (neural mobilization and
infrared group). The dominant arm was identified using the Edinburgh Handedness
Inventory19), NM involved placing
subject in the supine position. The neck was pulled and tilted to the opposite side of the
limb to be tested, and the shoulders were lowered and abducted at 90 ° followed by external
rotation. Gradually, the elbow, wrist and fingers were extended. When slight tension was
reported by a subject, the therapist decreased the angle of the elbow and oscillatory
movements of the wrist for a minute, followed by three minutes of rest. Neural mobilization
three sets20,21,22,23). In G1 (control), the participants rested comfortably for 25
minutes lying on the table in the supine position, with their arms extended along the body.
In G2, a NM technique for the median nerve was applied. In G3, infrared (IR) was applied for
15 minutes from 40 cm above the forearm24). In G4, IR was applied for 15 minutes followed by a NM technique for
the median nerve.  Before and after the intervention subjects scored a Visual Analogue Scale (VAS) to identify
the intensity of pain experienced. Goniometric measurements were made before and after the
intervention using a universal goniometer in order to evaluate the effects of the
interventions on the maximum angle elbow extension. The Upper Limb Neurodynamical Test
(ULNT) was performed at the same position described for the NM technique for the median
nerve, and the reported individual neural tension was measured based on the angle. The
reference points used for the goniometer were the styloid process, medial epicondyle of the
humerus and the coracoid process25), which
were identified and marked before positioning the individuals in order to reduce the chances
of error during the goniometry.  All protocols were performed by the same examiner and the goniometric analyses were
performed by an assistant.  Statistical analyses were performed using the BioEstat 5.3 program. The Kruskal-Wallis and
the Dunn test were performed to compare the groups, and significance was accepted for values
of p ≤0.05. The differences in elbow extension were analyzed as well as the delta of the
values of VAS (Delta=final value −initial value).

BODY.RESULTS:
The Kruskal-Wallis test found no significant differences in the VAS data, H (3)=1.3307,
p=0.72. The group that received neural mobilization reported higher pain scores (Table 1Table 1.VAS Values: The median, and maximum and minimum values of Delta of VAS scores of
each intervention groupGroupsMedianMean rankMin–MaxControl220.800–2Neural Mob.221.500–5Infrared017.000–0Infrared and Neural Mob.322.700–3*p<0.05, Kruskal-Wallis test). Analysis of the gain in the range of motion there were very significant
showed differences among the intervention groups M (3)=11.3837, p≤0.01 (Tables 2Table 2.Goniometry values (degrees): The median, and maximum and minimum values of the
gain in the range of motion elicited by the intervention of each intervention
groupGroupsMedianMean rankMin–MaxControl110.60*−9–5Neural Mob.719.85*−2–23Infrared10.526.35*1–20Infrared and Neural Mob.8.525.20*−1–50*p<0.05, Kruskal-Wallis test and 3Table 3.Differences in the averages of goniometry values among the groupsDifferences between the averages G1–G26.50 degreesG1–G35.35 degreesG1–G49.25 degreesG2–G31.15 degreesG2–G415.75 degrees *G3–G414.60 degrees *G1: control, G2: neural mobilization, G3: infrared, and G4: infrared plus neural
mobilization. *p<0.05, Kruskal-Wallis test).

BODY.DISCUSSION:
The aim of this study was to analyze the acute effects of superficial heat with neural
mobilization for the median nerve on the elbow extension range. As expected, the combination
of NM and infrared significantly increased the range of motion in comparison to the control
group. The nervous system has two intimately related components: a connective tissue
component and a neural tissue component. NM and infrared act on theses tissues and increase
their extensibility. Increased elbow extension after NM was also reported by Vasconcelos,
Lins and Dantas10), whose sample and
method of measuring elbow extension were similar to those of this study. The increase in
elbow extension is explained by the ability of NM to restore the nerve system movement and
musculoskeletal structures innervated by it26, 27).  The combination of NM and hyperthermia proved to be more effective than NM alone, because
infrared has an acute effect on the mechanical interface, acting directly on the tissue
collagen in the muscles modifying its viscoelastic properties, as well as causing sensory
and analgesic stimulation enhancing tolerance to stretching28). The heat transmitted by infrared penetrates about one centimeter
in depth by thermal conduction29, 30), preferably influencing the most
superficial tissues24). IR effects are
elicited by vasodilation which increases the supply of nutrients and oxygen to the tissues
decreasing feelings of fatigue31,32,33).
In addition, muscle relaxation resulting from an increase in the sensitivity of the
neurotendineous organs34), and a decrease
in pain as a consequence of increased stretching and pain tolerance, allows a greater range
of motion28).  Sousa et al.29) used a sample of 103
patients with impact syndrome diagnosis and verified the effect of isolated kinesiotherapy
associated with infrared or laser GaAs. They verified that the combination of the techniques
does not influence the outcome of the intervention. Thus, the use of human movement is still
one of the main intervention resources that the physiotherapist has to treat injuries.
However, unlike the study of Sousa et al.29), the sample used in this study consisted of asymptomatic
individuals, and inflammatory processes or other variables difficult to control, such as
pain level or degree of injury were not limiting factors.  In the present study, unlike other studies, NM was not superior to the other techniques
compared with it10, 35). Its use resulted in a significant increase in elbow range of
motion, showing it is an effective remedy for the treatment of ANT. Differences between the
present results and those reported in the literature may be explained by the capacity for
perception of pain, a subjective variable that is influenced by psychosocial factors36, 37). Pain influences the range of motion10).  This research provides new experimental evidence that NM in combination with superficial
heat elicits an immediate effect on elbow range of motion compared to NM alone. Future
controlled trials are warranted to evaluate changes in the range of motion in different
musculoskeletal disorders that can be treated with NM and to compare this technique with
other physiotherapeutic modes.

Question: Compared to G3: infrared what was the result of G4: infrared plus neural mobilization on elbow extension?
Evidence: G1: control, G2: neural mobilization, G3: infrared, and G4: infrared plus neural
mobilization. *p<0.05
Answer: significantly increased