Assessment of range and quality of neck movement using a smartphone-based application.

This study had the objective of measuring the validity of using a smartphone-based application to measure range of motion (ROM) and quality of movement (QOM) of neck motion by comparing it with 3D-motion capture analysis. METHODS: Thirty healthy volunteers participated in this cross-sectional study. A helmet fitted with markers for motion capture analysis and a smartphone were fastened to the head of the participants. The smartphone recorded data using a beta version of Balancy (MEDEI, Denmark). Assessments of full active movement in transverse and sagittal planes were performed. Recordings were made simultaneously with the camera system and the smartphone. ROM and jerkiness were compared with a repeated measures ANOVA and a Pearson product moment was calculated to compare the outcomes from the different applications. Bland-Altman plots were generated to determine the levels of agreement. RESULTS: No difference was found between modalities when comparing measurements of jerkiness or ROM. An excellent Pearson product moment was found for the outcomes of the two modalities for ROM (Pearson's r: 0.83 - 0.96) and jerkiness (Pearson's r: 0.86 - 0.95). The Bland-Altman plot revealed a systemic offset where the phone consistently measured higher values for ROM and lower values for jerkiness. CONCLUSIONS: This study demonstrated that a smartphone-based application can be used to accurately measure ROM and jerkiness during neck movements. These results indicate the utility of using a smartphone-based application to assess neck movement in humans. The findings have implications for assessment of neck movement in research and clinical practice.

Increased postural stiffness during challenging postural tasks in patients with knee osteoarthritis with high pain sensitization.

BACKGROUND: Postural stability is affected in knee osteoarthritis patients who present with pain but the link to pain sensitization is unclear. METHODS: Patients with knee osteoarthritis completed the Knee Injury and Osteoarthritis Outcome Score and pressure pain thresholds were assessed bilaterally at the knee, lower leg and forearm prior to standing quietly (1 min) on a force platform in four conditions: Firm surface with open eyes, firm surface with closed eyes, soft surface with open eyes, and soft surface with closed eyes. Pain intensity during standing was assessed via numerical rating scale. Postural stability was assessed by the range, velocity, and standard deviation of the Center of Pressure (CoP) extracted from the force platform. The means of three repeated measures per standing condition were analysed. High-sensitization and low-sensitization groups were defined based on bilateral pressure pain thresholds from leg and arm. FINDINGS: Fifty-six patients were included. Compared with the low-sensitization group, the high-sensitization group demonstrated 1) smaller pressure pain thresholds at the knee (P < 0.05) although the Knee Injury and Osteoarthritis Outcome Score and pain intensity were not significantly different between groups, and 2) smaller range of the CoP in the anterior-posterior direction during the soft surface with closed eyes condition (P < 0.05). INTERPRETATION: Smaller CoP range suggest that patients with more widespread pain sensitivity have increased postural stiffness compared with the low-sensitization group. The greater stiffness found in high-sensitization patients under sensory restrictions (closed eyes and reduced proprioception) might relate to restricted integration of sensory information due to widespread pain sensitization.

Blood flow after contraction and cuff occlusion is reduced in subjects with muscle soreness after eccentric exercise.

Delayed onset muscle soreness (DOMS) occurs within 1-2 days after eccentric exercise, but the mechanism mediating hypersensitivity is unclear. This study hypothesized that eccentric exercise reduces the blood flow response following muscle contractions and cuff occlusion, which may result in accumulated algesic substances being a part of the sensitization in DOMS. Twelve healthy subjects (five women) performed dorsiflexion exercise (five sets of 10 repeated eccentric contractions) in one leg, while the contralateral leg was the control. The maximal voluntary contraction (MVC) of the tibialis anterior muscle was recorded. Blood flow was assessed by ultrasound Doppler on the anterior tibialis artery (ATA) and within the anterior tibialis muscle tissue before and immediately after 1-second MVC, 5-seconds MVC, and 5-minutes thigh cuff occlusion. Pressure pain thresholds (PPTs) were recorded on the tibialis anterior muscle. All measures were done bilaterally at day 0 (pre-exercise), day 2, and day 6 (post-exercise). Subjects scored the muscle soreness on a Likert scale for 6 days. Eccentric exercise increased Likert scores at day 1 and day 2 compared with day 0 (P<.001). Compared with pre-exercise (day 0), reduced PPT (~25%, P<.002), MVC (~22%, P<.002), ATA diameter (~8%, P<.002), ATA post-contraction/occlusion blood flow (~16%, P<.04), and intramuscular peak blood flow (~23%, P<.03) were found in the DOMS leg on day 2 but not in the control leg. These results showed that eccentric contractions decreased vessel diameter, impaired the blood flow response, and promoted hyperalgesia. Thus, the results suggest that the blood flow reduction may be involved in the increased pain response after eccentric exercise.

Altered pain sensitivity and axioscapular muscle activity in neck pain patients compared with healthy controls.

BACKGROUND: Previous studies have indicated that neck pain patients feel increased symptoms following upper limb activities, and altered axioscapular muscle function has been proposed as a contributing factor. METHODS: Pain sensitivity and muscle activity, during arm movements, were assessed in neck pain patients and controls. Patients with ongoing insidious-onset neck pain (IONP, N = 16) and whiplash-associated disorders (WAD, N = 9) were included along with sex- and age-matched controls (N = 25). Six series of repeated arm abductions were performed during electromyographic (EMG) recordings from eight bilateral muscles. The first and last three series were separated by 8 min and 42 s, respectively. Each series consisted of three slow and three fast movements. Pressure pain thresholds (PPTs) were recorded bilaterally from neck, head and arm at baseline, after the third and sixth movement series. Pain intensity was recorded on an electronic visual analogue scale (VAS). RESULTS: Larger pain areas and higher VAS scores were found in patients compared with controls (p < 0.001), and in patients, the VAS scores increased in the course of movements (p < 0.02). PPTs were lower in patients compared with controls at all sites (p < 0.03), and these decreased during arm movements in the IONP group (p < 0.03), while increasing at head and neck sites in controls (p < 0.04). During the slow movements, increasing serratus anterior EMG activity was found in the series with short breaks in-between for the WAD group compared with IONP and controls (p < 0.001). CONCLUSION: Axioscapular movement caused different responses in pain sensitivity and muscle activity between neck pain patient groups compared with controls. SIGNIFICANCE: Neck pain patients report increased symptoms following upper limb activities. This study shows that repeated arm movements caused differentiated responses in pain sensitivity and muscle activity between subgroups of neck pain patient and asymptomatic controls. Such findings may be of great clinical significance when planning rehabilitation for this patient population.

Experimental pain in the groin may refer into the lower abdomen: Implications to clinical assessments.

OBJECTIVES: To investigate the effects of experimental adductor pain on the pain referral pattern, mechanical sensitivity and muscle activity during common clinical tests. DESIGN: Repeated-measures design. METHODS: In two separate sessions, 15 healthy males received a hypertonic (painful) and isotonic (control) saline injection to either the adductor longus (AL) tendon to produce experimental groin pain or into the rectus femoris (RF) tendon as a painful control. Pain intensity was recorded on a visual analogue scale (VAS) with pain distribution indicated on body maps. Pressure pain thresholds (PPT) were assessed bilaterally in the groin area. Electromyography (EMG) of relevant muscles was recorded during six provocation tests. PPT and EMG assessment were measured before, during and after experimental pain. RESULTS: Hypertonic saline induced higher VAS scores than isotonic saline (p<0.001), and a local pain distribution in 80% of participants. A proximal pain referral to the lower abdominal region in 33% (AL) and 7% (RF) of participants. Experimental pain (AL and RF) did not significantly alter PPT values or the EMG amplitude in groin or trunk muscles during provocation tests when forces were matched with baseline. CONCLUSIONS: This study demonstrates that AL tendon pain was distributed locally in the majority of participants but may refer to the lower abdomen. Experimental adductor pain did not significantly alter the mechanical sensitivity or muscle activity patterns.

Reduced complexity of force and muscle activity during low level isometric contractions of the ankle in diabetic individuals.

BACKGROUND: This study evaluated the structure and amount of variability of surface electromyography (sEMG) patterns and ankle force data during low-level isometric contractions in diabetic subjects with different degrees of neuropathy. METHODS: We assessed 10 control subjects and 38 diabetic patients, classified as absent, mild, moderate, or severe neuropathy, by a fuzzy system based on clinical variables. Multichannel sEMG (64-electrode matrix) of tibialis anterior and gastrocnemius medialis muscles were acquired during isometric contractions at 10%, 20%, and 30% of the maximum voluntary contraction, and force levels during dorsi- and plantarflexion were recorded. Standard deviation and sample entropy of force signals were calculated and root mean square and sample entropy were calculated from sEMG signals. Differences among groups of force and sEMG variables were verified using a multivariate analysis of variance. FINDINGS: Overall, during dorsiflexion contractions, moderate and severe subjects had higher force standard deviation and moderate subjects had lower force sample entropy. During plantarflexion, moderate subjects had higher force standard deviation and all diabetic subjects had lower entropy. Tibialis anterior presented higher root mean square in absent group and lower entropy in mild subjects. For gastrocnemius medialis, entropy was higher in severe and lower in moderate subjects. INTERPRETATION: Diabetic neuropathy affects the complexity of the neuromuscular system during low-level isometric contractions, reducing the system's capacity to adapt to challenging mechanical demands. The observed patterns of neuromuscular complexity were not associated with disease severity, with the majority of alterations recorded in moderate subject.

Pain-evoked trunk muscle activity changes during fatigue and DOMS.

BACKGROUND: Muscle pain may reorganize trunk muscle activity but interactions with exercise-related muscle fatigue and delayed onset muscle soreness (DOMS) is to be clarified. METHODS: In 19 healthy participants, the trunk muscle activity during 20 multi-directional unpredictable surface perturbations were recorded after bilateral isotonic saline injections (control) and during unilateral and bilateral hypertonic saline-induced low back pain (LBP) in conditions of back muscle fatigue (Day-1) and DOMS (Day-2). Pain intensity and distribution were assessed by visual analogue scale (VAS) scores and pain drawings. The degree of fatigue and DOMS were assessed by Likert scale scores. Root-mean-square electromyographic (RMS-EMG) signals were recorded post-perturbation from six bilateral trunk muscles and the difference from baseline conditions (Delta-RMS-EMG) was extracted and averaged across abdominal and back muscles. RESULTS: In DOMS, peak VAS scores were higher during bilateral control and bilateral saline-induced pain than fatigue (p < 0.001) and during bilateral compared with unilateral pain (p < 0.001). The saline-induced pain areas were larger during DOMS than fatigue (p < 0.01). In response to surface perturbations during fatigue and DOMS, the back muscle Delta-RMS-EMG increased during bilateral compared with unilateral pain and control injections (p < 0.001) and decreased during unilateral pain compared with control injections (p < 0.04). In DOMS compared with fatigue, the post-perturbation Delta-RMS-EMG in back muscles was higher during bilateral pain and lower during unilateral pain (p < 0.001). The abdominal Delta-RMS-EMG was not significantly affected. CONCLUSION: Facilitated and attenuated back muscle responses to surface perturbations in bilateral and unilateral LBP, respectively, was more expressed during exercise-induced back muscle soreness compared with fatigue. SIGNIFICANCE: Back muscle activity decreased during unilateral and increased during bilateral pain after unpredictable surface perturbations during muscle fatigue and DOMS. Accumulation effects of DOMS on pain intensity and spreading and trunk muscle activity after pain-induction.

Bilateral experimental neck pain reorganize axioscapular muscle coordination and pain sensitivity.

BACKGROUND: Neck pain is a large clinical problem where reorganized trunk and axioscapular muscle activities have been hypothesised contributing to pain persistence and pain hypersensitivity. This study investigated the effects of bilateral experimental neck pain on trunk and axioscapular muscle function and pain sensitivity. METHODS: In 25 healthy volunteers, bilateral experimental neck pain was induced in the splenius capitis muscles by hypertonic saline injections. Isotonic saline was used as control. In sitting, subjects performed slow, fast and slow-resisted unilateral arm movements before, during and after injections. Electromyography (EMG) was recorded from eight shoulder and trunk muscles bilaterally. Pressure pain thresholds (PPTs) were assessed bilaterally at the neck, head and arm. Data were normalized to the before-measures. RESULTS: Compared with control and post measurements, experimental neck pain caused (1) decreased EMG activity of the ipsilateral upper trapezius muscles during all but slow-resisted down movements (p < 0.001), and (2) increased EMG activity in the ipsilateral erector spinae muscle during slow and fast movements (p < 0.02), and in the contralateral erector spinae muscle during all but fast up and slow-resisted down movements (p < 0.007). The PPTs in the painful condition increased at the head and arm compared with post measurements and the control condition (p < 0.001). In the post-pain condition, the neck PPT was decreased compared with the control condition (p < 0.001). CONCLUSION: Acute bilateral neck pain reorganized axioscapular and trunk muscle activity together with local hyperalgesia and widespread hypoalgesia indicating that acute neck pain immediately affects trunk and axioscapular function which may affect both assessment and treatment. SIGNIFICANCE: Bilateral clinical neck pain alters axioscapular muscle coordination but only effects of unilateral experimental neck pain has been investigated. Bilateral experimental neck pain causes task-dependent reorganized axioscapular and trunk muscle activity in addition to widespread decrease in pressure pain sensitivity.

Resisted adduction in hip neutral is a superior provocation test to assess adductor longus pain: An experimental pain study.

The criterion of long-standing groin pain diagnoses in athletes usually relies on palpation and clinical tests. An experimental pain model was developed to examine the clinical tests under standardized conditions. Pain was induced by hypertonic saline injected into the proximal adductor longus (AL) tendon or rectus femoris (RF) tendon in 15 healthy male participants. Isotonic saline was injected contralaterally as a control. Pain intensity was assessed on a visual analog scale (VAS). Resisted hip adduction at three different angles and trunk flexion were completed before, during, and after injections. Pain provocation in the presence of experimental pain was recorded as a true positive compared with pain provocation in the non-pain conditions. Similar peak VAS scores were found after hypertonic saline injections into the AL and RF and both induced higher VAS scores than isotonic saline (P < 0.01). Adduction at 0° had the greatest positive likelihood ratio (+LR = 2.8, 95%CI: 1.09-7.32) with 45° (-LR = 0.0, 95%CI: 0.00-1.90) and 90° (-LR = 0.0, 95%CI: 0.00-0.94) having the lowest negative LR. This study indicates that the 0° hip adduction test resisted at the ankles optimizes the diagnostic procedure without compromising diagnostic capacity to identify experimental groin pain. Validation in clinical populations is warranted.

Reorganised motor control strategies of trunk muscles due to acute low back pain.

This study assessed how the low back motor control strategies were affected by experimental pain. In twelve volunteers the right m. longissimus was injected by hypertonic and isotonic (control) saline. The pain intensity was assessed on a visual analog scale (VAS). Subjects were seated on a custom-designed chair including a 3-dimensional force sensor adjusted to the segmental height of T1. Electromyography (EMG) was recorded bilaterally from longissimus, multifidus, rectus abdominis, and external oblique muscles. Isometric trunk extensions were performed before, during, and after the saline injections at 5%, 10%, and 20% of maximum voluntary contraction force. Visual feedback of the extension force was provided whereas the tangential force components were recorded. Compared with isotonic saline, VAS scores were higher following hypertonic saline injections (P<.01). Experimental low back pain reduced the EMG activity bilaterally of the rectus abdominis muscles during contractions at 10% and 20% MVC (P<.01) although force accuracy and tangential force variability was not affected. Increased variability in the tangential force composition was found during pain compared with the non-painful condition (P<.05). The immediate adaptation to pain was sufficient to maintain the quality of the task performance; however the long-term consequence of such adaptation is unknown and may overload other structures.

Impaired anticipatory postural adjustments due to experimental infrapatellar fat pad pain.

BACKGROUND: Anticipatory postural adjustments (APAs) are motor responses generated to stabilize balance prior to voluntary movement. This study investigated how infrapatellar fat pad pain induces reorganization of APAs during reaction time tasks. It has been hypothesized that knee pain may cause insufficient APAs, thereby impairing the balance. METHODS: While standing, 12 healthy men performed two reaction time tasks (shoulder flexion of the dominant side and bilateral heel lift, respectively) before, during and after experimental infrapatellar fat pad pain induced in the dominant side by injections of hypertonic saline. Isotonic saline was injected as control. The reaction time task performance was assessed by peak angle and peak angular velocity. Timing and intensity of the postural muscle activity were recorded by surface electromyography. RESULTS: The reaction time task performance was not significantly affected by experimental pain. The onset of muscle activity in vastus medialis, vastus lateralis and tibialis anterior muscles on the dominant side during the bilateral heel lift task was significantly delayed during pain, and their muscle activity was reduced when compared with non-painful sessions (p < 0.05). The contralateral vasti muscles demonstrated early onset during pain compared with the non-painful session of the same task (p ≤ 0.05). CONCLUSIONS: This study demonstrates that knee pain reorganizes the APAs which may destabilize the balance control. The knee pain-related reorganization of postural muscle activity during APA may be a part of the central modulation to maintain posture and protect the painful limb while preserving the reaction task movement performance.

Uso del aparato bucal "PMpositioner" en el tratamiento del ronquido y la apnea obstructiva del sueño / Use of PMpositioner oral appliance in the treatment of snoring and mild obstructive sleep apnea

La elección de un aparato bucal apropiado para lograr los mejores resultados en el tratamiento de la apnea obstructiva del sueño es importante. El objetivo de este estudio fue evaluar el efecto de un aparato bucal específico, el PMPositioner, para el tratamiento del ronquido y la apnea obstructiva del sueño leve, a través de polisomnografía y la Escala de Epworth del sueño, después de seis meses de uso del mencionado aparato. Se incluyeron en el estudio 17 pacientes divididos en dos grupos: un grupo de roncadores (n=7) y otro grupo (n=10) con apnea obstructiva leve. Los resultados fueron significativos para el segundo grupo, revelando una disminución en el índice de apnea-hipoapnea de 7,4 +- 5,0 a 3,0 +- 2,5 (p<0.05), aumento del sueño REM de 16,0+-4,0 a 19+-6,0 y una mejora de la somnolencia en la Escala Epworth de 12,5+-5,4 a 7,4+-2,4. Se constató una disminución en los ronquidos y los síntomas subjetivos. PMPositioner, fue efectivo en el tratamiento de los ronquidos y la apnea obstructiva leve, la reducción de la somnolencia y de otros síntomas.

The choice of an adequate oral appliance is very important in the treatment of obstructive sleep apnea. The present study evaluated the effect of PMPositioner for the treatment of snoring and mild obstructive sleep apneathrough polysomnography and Epworth Sleep Scale prior to treatment and after six months. Seventeen patients, divided into 2 groups, snoring (n=7) and 10 with mild obstructive sleep apnea were enrolled. The results were significant for obstructive sleep apnea group reveling a decrease in the apnea/hypopnea index from 7.4±5.0 to 3.0±2.5 (p<0.05), anincrease in oxigen saturation from 88.0±6.0 to 90.0±2.8 (p<0.05), an increase in REM sleep from 16.0±6.0 to 19±4.0 and a sleepiness improved in from 12.5±5.4 to 7.4±2.4. Furthermore, it was noticed an improvement in snoring and subjective symptoms. The PM Positioner is efficient in the treatment of snoring and mild obstructive sleep apnea and in reduction of sleepness and others symptoms.

Role of ankle mobility in foot rollover during gait in individuals with diabetic neuropathy.

BACKGROUND: The purpose of this study was to investigate the ankle range of motion during neuropathic gait and its influence on plantar pressure distribution in two phases during stance: at heel-strike and at push-off. METHODS: Thirty-one adults participated in this study (control group, n=16; diabetic neuropathic group, n=15). Dynamic ankle range of motion (electrogoniometer) and plantar pressures (PEDAR-X system) were acquired synchronously during walking. Plantar pressures were evaluated at rearfoot, midfoot and forefoot during the two phases of stance. General linear model repeated measures analysis of variance was applied to investigate relationships between groups, areas and stance phases. FINDINGS: Diabetic neuropathy patients walked using a smaller ankle range of motion in stance phase and smaller ankle flexion at heel-strike (P=0.0005). Peak pressure and pressure-time integral values were higher in the diabetic group in the midfoot at push-off phase when compared to heel-strike phase. On the other hand, the control group showed similar values of peak pressure in midfoot during both stance phases. INTERPRETATION: The ankle mobility reduction observed could be associated to altered plantar pressure distribution observed in neuropathic subjects. Results demonstrated that midfoot and forefoot play a different role in subjects with neuropathy by receiving higher loads at push-off phase that are probably due to smaller ankle flexion at stance phase. This may explain the higher loads in anterior areas of the foot observed in diabetic neuropathy subjects and confirm an inadequate foot rollover associated to the smaller ankle range of motion at the heel-strike phase.

Efeito da posição relativa do joelho sobre a carga mecânica interna durante o agachamento / Effect of relative knee position on internal mechanical loading while squatting

CONTEXTUALIZAÇÃO: Existe um conceito difundido entre professores de educação física, fisioterapeutas e ortopedistas de que o joelho não deve ser demasiadamente anteriorizado em relação à ponta do pé na direção ântero-posterior durante qualquer tipo de agachamento de modo a diminuir a carga mecânica sobre o joelho. No entanto, são escassas as evidências quantitativas que corroboram esse conceito. OBJETIVO: Estimar forças e torque na articulação do joelho em indivíduos saudáveis durante o exercício de agachamento livre com peso em dois modos diferentes de execução: a) joelho não ultrapassando a linha vertical que passa pelos dedos do pé; b) joelho ultrapassando essa linha vertical. MÉTODOS: Análise tridimensional com câmeras de vídeo e plataforma de força do movimento de agachamento em dez adultos jovens saudáveis. Quinze repetições em cada condição do agachamento por sujeito foram executadas sobre uma plataforma de força. As forças e torques articulares no tornozelo, joelho e quadril foram calculados pelo procedimento de dinâmica inversa. RESULTADOS: Os resultados obtidos mostram que o pico do torque no joelho é, em média, cerca de 38 ± 31 por cento e a força patelofemoral é, em média, cerca de 28 ± 27 por cento maiores na condição ultrapassando o joelho que na condição não ultrapassando o joelho. CONCLUSÕES: Esses resultados demonstram que não ultrapassar o joelho da linha do pé diminui a força de compressão patelofemoral, levando assim a uma menor solicitação mecânica nessa articulação.

BACKGROUND: There is a widespread notion among physical education teachers, physical therapists and orthopedists that, during any type of squatting, the knee should not be brought forward too much in relation to the tip of the foot, so as to reduce the mechanical loading on the knee. However, there is little quantitative evidence to corroborate this notion. OBJECTIVE: To estimate the forces and torque on the knee joint in healthy individuals during free squatting exercises using weights performed in two different ways: a) knee not going beyond a vertical line going through the toes; b) knee going beyond this vertical line. METHOD: Three-dimensional analysis using video cameras and a force platform was performed on squatting movements performed by ten healthy young adults. Fifteen repetitions of each of the two squatting conditions were performed by each subject on the force plate. The forces and joint torque at the ankle, knee and hip were calculated using an inverse dynamic procedure. RESULTS: The results obtained showed that the mean peak torque on the knee was around 38 ± 31 percent greater, and the mean patellofemoral force was around 28 ± 27 percent greater, when the knee went beyond the tip of the foot, than when it did not. CONCLUSIONS: These results demonstrate that, when the knee does not go beyond the line of the foot, the patellofemoral compression force is less, which leads to lower mechanical demand on this joint.