Gender differences in ground reaction force following perturbations in subjects with low back pain

The Sensitivity of Thresholds by Ground Reaction Force and Postural Stability in Subjects With and Without Navicular Drop

Understanding plantar pressure changes is an important component of the functional evaluation of subjects with flat foot. However, the altered postural control determined by the threshold from the vertical ground reaction force (GRF) requires clarification. The purpose of our study was to investigate the various GRF thresholds in subjects with and without flat foot during 1-leg standing. We included 34 control subjects and 30 subjects with flat foot in the present study. They performed the 1-leg standing test for 30 seconds, with the contralateral hip and knee flexed approximately 90°. The sensitivity of the various GRF thresholds (3, 7, 15, 50, and 100 N) for the postural stability index was analyzed with and without visual input. The standing times for the control and flat foot groups were 23.76 ± 4.42 and 21.78 ± 6.59 seconds, respectively, with no significant differences (t = 1.23; p = .22). The 2 groups demonstrated a significant interaction between the visual condition and the threshold levels (F = 11.40; p = .001). The postural stability index was significantly different in the eyes-open condition (0.95 ± 0.08 for the control group versus 0.84 ± 0.23 for the flat foot group; t = 2.29; p = .02). However, no difference was found in the eyes-closed condition (0.94 ± 0.10 for the control group versus 0.81 ± 0.30 for the flat foot group; t = 1.45; p = .15). These results indicate that GRF thresholds less than the 15N setting are sensitive to detect postural stability between groups, especially in the eyes-open condition. The GRF threshold setting, in addition to the visual condition, could alter the outcomes of sensitive plantar pressure changes in subjects with flat foot.

Gender difference of shoulder-pelvic kinematic integration for trunk rotation directions in healthy older adults

BACKGROUND

The trunk coordination pattern has been extensively studied, and there is a higher pain prevalence and asymmetry in female older adults. However, there is a lack of investigation of different directions of trunk rotation and asymmetrical compensatory strategies of motor control between genders. The purpose of this study was to investigate shoulder and pelvic ranges of motion (ROM) as well as relative phases (RP) for the different directions of trunk rotation between genders in healthy older adults.

METHODS

There were 62 right hand dominant older adults in this study (31 female subjects (68.4 [5.62]years) and 31 male subjects (68.7 [5.68]years)). The participants performed trunk axial rotation from the left to the right direction (RP1) and then returned to the left side (RP2), three times repeatedly in standing. The measurements included shoulder and pelvic ROM, RP1, and RP2. The RP was defined as the average absolute relative phase, which was the difference between the phase angle of the shoulder and the phase angle of the pelvis during trunk rotation.

FINDINGS

The female group demonstrated significantly greater pelvic rotation compared to the male group (98.64 [24.67] vs. 86.96 [18.97]; t=2.09, p=0.04) during trunk rotation. The pelvic ROM demonstrated a significant positive correlation with shoulder ROM in both genders; however, the RP was negatively correlated with the pelvis. For pelvic rotation, the male group demonstrated a negative correlation with RP1 (r=-0.68, p<0.01) and RP2 (r=-0.60, p<0.01) while the female group demonstrated a negative correlation with RP2 (r=-0.53, p<0.01). The ageing factor demonstrated negative correlations with ROM for the shoulder and pelvis in both genders.

INTERPRETATION

Although no gender difference was indicated on the direction of RP, the pelvic ROM was significantly lesser in the male group. The male group demonstrated lesser pelvic rotation in both directions of rotation; however, the female group showed lesser pelvic rotation in RP2. The male group demonstrated stiffened pelvic rotation and greater shoulder rotation in both directions while the female group demonstrated pelvic stiffness only in the direction from right to left rotation. Clinicians need to consider this directional asymmetry of trunk rotation to enhance integrated shoulder-pelvic coordination in female older adults.

MINI ABSTRACT

A coordinative pattern of different directions of trunk rotation was investigated in healthy older adults. The pelvic range of motion was lesser in the male group compared with the female group. The female group demonstrated pelvic stiffness only in the direction from right to left rotation, while the male group demonstrated pelvic stiffness in both directions. Clinicians need to understand the gender difference of directional coordination as integrated coordination in female older adults.

Devices and tasks involved in the objective assessment of standing dynamic balancing - A systematic literature review

BACKGROUND

Static balancing assessment is often complemented with dynamic balancing tasks. Numerous dynamic balancing assessment methods have been developed in recent decades with their corresponding balancing devices and tasks.

OBJECTIVE

The aim of this systematic literature review is to identify and categorize existing objective methods of standing dynamic balancing ability assessment with an emphasis on the balancing devices and tasks being used.

DATA SOURCES

Three major scientific literature databases (Science Direct, Web of Science, PLoS ONE) and additional sources were used.

STUDY SELECTION

Studies had to use a dynamic balancing device and a task described in detail. Evaluation had to be based on objectively measureable parameters. Functional tests without instrumentation evaluated exclusively by a clinician were excluded. A total of 63 articles were included.

DATA EXTRACTION

The data extracted during full-text assessment were: author and date; the balancing device with the balancing task and the measured parameters; the health conditions, size, age and sex of participant groups; and follow-up measurements.

DATA SYNTHESIS

A variety of dynamic balancing assessment devices were identified and categorized as 1) Solid ground, 2) Balance board, 3) Rotating platform, 4) Horizontal translational platform, 5) Treadmill, 6) Computerized Dynamic Posturography, and 7) Other devices. The group discrimination ability of the methods was explored and the conclusions of the studies were briefly summarized.

LIMITATIONS

Due to the wide scope of this search, it provides an overview of balancing devices and do not represent the state-of-the-art of any single method.

CONCLUSIONS

The identified dynamic balancing assessment methods are offered as a catalogue of candidate methods to complement static assessments used in studies involving postural control.

The ground reaction force thresholds for detecting postural stability in participants with and without flat foot

Foot mobility commonly contributes to injury via altered motion of the lower extremities. However, there is a lack of understanding of sensitive kinetic changes with flat foot. The purpose of this study was to investigate the threshold that best distinguishes between participants with and without flat foot. The kinetic stability index was developed based on the three-dimensional data from the ground reaction force (GRF) during one leg standing. In total, 34 control participants and 30 participants with flat foot were asked to maintain one leg standing for 25s with the contra lateral hip and knee flexed approximately 90°. The various thresholds (3, 7, 15, 30, 50, and 200N) were analyzed by the kinetic stability index. The standing time was not significantly different between groups (t=1.07, p=0.28); however, there were significant differences on threshold level (F=369.23, p=0.001) as well as group interactions with threshold (F=6.72, p=0.01). The post hoc test indicated that less than 15N was the best to detect the kinetic stability index between the groups. Clinicians need to understand sensitive threshold settings to differentiate the participants with and without flat foot. The threshold changes might be altered to detect postural deficits by the kinetic stability index.

A kinematic and kinetic analysis of spinal region in subjects with and without recurrent low back pain during one leg standing

BACKGROUND

The purpose of this study was to evaluate the relationship between normalized kinematic and kinetic stability indices for spinal regions with eyes-open and eyes-closed conditions during non-dominant leg standing between subjects with recurrent low back pain and control subjects.

METHODS

The kinematic stability index for the spinal regions (core spine model, lumbar spine, lower and upper thorax) and the kinetic stability index from force plate were measured. All participants were asked to maintain non-dominant leg standing with the dominant hip and knee flexed approximately 90 degrees for 25 seconds. Forty-two participants enrolled in the study, including 22 subjects with low back pain (12 male, 10 female) and 20 control subjects (12 male, 8 female).

FINDINGS

For the kinematic index for stability, the visual condition (F=30.06, p=0.0001) and spinal region (F=10.82, p=0.002) were statistically significant. The post hoc test results indicated a significant difference in the lumbar spine compared with the upper and lower thorax and the core spine model. The kinetic stability (average [standard deviation]) during the eyes-closed condition significantly decreased in the low back pain group (t=-3.24, p=0.002).

INTERPRETATION

The subjects with recurrent low back pain demonstrated higher lumbar spine stability in eyes-open condition. This higher stability of the lumbar spine might be due to a possible pain avoiding strategy from the standing limb. The low back pain group also significantly decreased kinetic stability during the eyes-closed condition. Clinicians need to consider both kinetic and kinematic indices while considering visual condition for lumbar spine stability in subjects with recurrent low back pain.

The Kinematics and Kinetics Analysis of the Lower Extremity in the Landing Phase of a Stop-jump Task

Large number of studies showed that landing with great impact forces may be a risk factor for knee injuries. The purpose of this study was to illustrate the different landing loads to lower extremity of both genders and examine the relationships among selected lower extremity kinematics and kinetics during the landing of a stop-jump task. A total of 35 male and 35 female healthy subjects were recruited in this study. Each subject executed five experiment actions. Lower extremity kinematics and kinetics were synchronously acquired. The comparison of lower extremity kinematics for different genders showed significant difference. The knee and hip maximum flexion angle, peak ground reaction force and peak knee extension moment have significantly decreased during the landing of the stop-jump task among the female subjects. The hip flexion angle at the initial foot contact phase showed significant correlation with peak ground reaction force during landing of the stop-jump task (r=-0.927, p<0.001). The knee flexion angle at the initial foot contact phase had significant correlation with peak ground reaction force and vertical ground reaction forces during landing of the stop-jump task (r=-0.908, p<0.001; r=0.812, P=0.002). A large hip and knee flexion angles at the initial foot contact with the ground did not necessarily reduce the impact force during landing, but active hip and knee flexion motions did. The hip and knee flexion motion of landing was an important technical factor that affects anterior cruciate ligament (ACL) loading during the landing of the stop-jump task.

[Possible changes in energy-minimizer mechanisms of locomotion due to chronic low back pain - a literature review]

One goal of the locomotion is to move the body in the space at the most economical way possible. However, little is known about the mechanical and energetic aspects of locomotion that are affected by low back pain. And in case of occurring some damage, little is known about how the mechanical and energetic characteristics of the locomotion are manifested in functional activities, especially with respect to the energy-minimizer mechanisms during locomotion. This study aimed: a) to describe the main energy-minimizer mechanisms of locomotion; b) to check if there are signs of damage on the mechanical and energetic characteristics of the locomotion due to chronic low back pain (CLBP) which may endanger the energy-minimizer mechanisms. This study is characterized as a narrative literature review. The main theory that explains the minimization of energy expenditure during the locomotion is the inverted pendulum mechanism, by which the energy-minimizer mechanism converts kinetic energy into potential energy of the center of mass and vice-versa during the step. This mechanism is strongly influenced by spatio-temporal gait (locomotion) parameters such as step length and preferred walking speed, which, in turn, may be severely altered in patients with chronic low back pain. However, much remains to be understood about the effects of chronic low back pain on the individual's ability to practice an economic locomotion, because functional impairment may compromise the mechanical and energetic characteristics of this type of gait, making it more costly. Thus, there are indications that such changes may compromise the functional energy-minimizer mechanisms.

Trunk Control Ability after Minimally Invasive Lumbar Fusion Surgery during the Early Postoperative Phase

[Purpose] Lumbar fusion has been used for spinal disorders when conservative treatment fails. The minimally invasive approach causes minimal damage to the back muscles and shortens the postoperative recovery time. However, evidence regarding functional recovery in patients after minimally invasive lumbar spinal fusion is limited. The purpose of this study was to investigate how trunk control ability is affected after minimally invasive lumbar fusion surgery during the early postoperative phase. [Subjects and Methods] Sixteen patients and 16 age- and sex-matched healthy participants were recruited. Participants were asked to perform a maximum forward reaching task and were evaluated 1 day before and again 1 month after the lumbar fusion surgery. Center of pressure (COP) displacement, back muscle strength, and scores for the Visual Analog Scale, and Chinese version of the modified Oswestry Disability Index (ODI) were recorded. [Results] The healthy control group exhibited more favorable outcomes than the patient group both before and after surgery in back strength, reaching distance, reaching velocity, and COP displacement. The patient group improved significantly after surgery in all clinical outcome measurements. However, reaching distance decreased, and the reaching velocity as well as COP displacement did not differ before and after surgery. [Conclusion] The LBP patients with lumbar fusion surgery showed improvement in pain intensity 1 month after surgery but no improvement in trunk control during forward reaching. The results provide evidence that the back muscle strength was not fully recovered in patients 1 month after surgery and limited their ability to move their trunk forward.

Effect of visual input on normalized standing stability in subjects with recurrent low back pain

Although a number of studies have evaluated kinematic stability changes in subjects with low back pain (LBP), the combined sensitivity of normalized standing stability from the ground force and kinematic rotational angle of the body segment were not carefully examined for postural responses. The purpose of this study was to evaluate normalized standing stability in subjects with and without recurrent LBP while they stood quietly with the tested foot parallel to the other lower extremity at hip width. The subjects were then instructed to stand freely on one leg for 25 s with the contra lateral hip flexed 90° based on dominance side (dominant leg vs. non-dominant lower extremity) and visual condition (eyes open vs. eyes closed). A total of 42 subjects (27 subjects without LBP and 15 subjects with LBP) participated in the study. The dominant leg standing stability was significantly different during the eyes closed condition (0.68±0.30 for control vs. 0.37±0.32 for LBP, T=-3.23, p=0.002) compared to the eyes open condition. The standing kinematic stability, especially of the dominant thigh, was greater in the control subjects than in the subjects with LBP (T=-2.43, p=0.02). This sensitive detection of kinematic imbalance with postural stability is important for effective rehabilitation strategies and to understanding compensatory mechanisms in subjects with recurrent LBP.

Lombalgia crônica: comparação entre duas intervenções na força inspiratória e capacidade funcional

INTRODUÇÃO: A dor lombar crônica apresenta alta incidência, grandes custos sociais e pessoais e esforços terapêuticos muitas vezes frustrantes. Faz-se necessário, então, avaliar os recursos fisioterapêuticos para entendê-los melhor e fundamentá-los cientificamente. OBJETIVOS: Comparar os efeitos entre duas intervenções fisioterapêuticas sobre a força muscular respiratória (FMR) e a capacidade funcional (CF) em pacientes com lombalgia crônica. MATERIAIS E MÉTODOS: Série de casos cuja amostra (n = 10), composta por portadores de dor lombar crônica, foi dividida aleatoriamente em grupo controle, que recebeu fisioterapia convencional (eletroanalgesia, massoterapia e flexibilização), e grupo experimental, que recebeu a cinesioterapia combinada (composta por técnicas de isostretching + treinamento sensório-motor aquático). A mensuração da CF, realizada pelo teste de caminhada de seis minutos (TC6), e da FMR, pelas pressões máximas inspiratória (Pimáx) e expiratórias (Pemáx) por meio de manuvacuometria, aconteceu antes (ΔINI) e após (ΔFIN) as intervenções, que duraram sete semanas, com três sessões semanais. As comparações foram feitas pelo Mann-Whitney e Wilcoxon (α = 0,05). RESULTADOS: No GE, observou-se melhora, intragrupo, na Pimáx (p = 0,0164), Pemáx (p = 0,0227) e TC6 (p = 0,0092), e, no GC, apenas no TC6 (p = 0,018). Nas comparações intergrupo, obteve-se Pimáx e Pemáx semelhantes na ΔINI, mas diferentes na ΔFIN (p = 0,0166; p = 0,0045); e no TC6, observou-se diferença significativa apenas na ΔINI (p = 0,0484). CONCLUSÃO: O isostretching e treinamento sensório-motor aquático foram eficazes na melhora da FMR e da CF, e o tratamento fisioterapêutico convencional foi efetivo apenas na melhora da CF.

Factors affecting shoulder-pelvic integration during axial trunk rotation in subjects with recurrent low back pain

INTRODUCTION

Shoulder-pelvic integration could play a central role in the control of dynamic posture and movement. However, kinematic coordination during axial trunk rotation has not been carefully investigated in subjects with recurrent low back pain (LBP). The purpose of this study was to compare the maximum rotational angles of the shoulders and pelvis in the transverse plane between subjects with and without recurrent LBP.

MATERIALS AND METHODS

A total of 38 age-matched subjects (19 control subjects: 69.00 ± 5.75 years old and 19 subjects with LBP: 68.79 ± 5.40 years old) participated in the study. The axial trunk rotation test was conducted in the upright position with bilateral hips and knees fully extended and both feet shoulder width apart.

RESULTS

The results of this study indicated that there was a difference in pelvic girdle rotation between groups (100.79 ± 26.46 in the control group, 82.12 ± 23.16 in the LBP group; t = 2.31, p = 0.02); however, there was no difference for the shoulder girdle (177.63 ± 36.98 in the control group, 156.42 ± 30.09 in the LBP group; t = 1.91, p = 0.06). There were interactions with age (F = 9.27, p = 0.004) and BMI (F = 7.50, p = 0.01) with the rotational angles of the shoulder and pelvis.

CONCLUSION

These results indicated a different pattern of trunk rotation movement with the age and BMI serving as important factors to consider for recurrent LBP. The results of our study also indicated a different pattern of shoulder and pelvic coordination with age and gender. Clinicians need to consider the consequences of limited shoulder-pelvic rotational angles, especially limited rotational angle on the pelvis during trunk axial rotation. Further studies are required to determine the causes of the underlying problems for clinical decision-making and altered shoulder-pelvic rotation in subjects with recurrent LBP.

Neural control of the lips differs for young and older adults following a perturbation

Aging impairs the control of many skilled movements including speech. The purpose of this paper was to investigate whether young and older adults adapt to lower lip perturbations during speech differently. Twenty men (10 young, 26 ± 3 years of age; 10 older, 60 ± 9 years of age) were requested to repeat the word ("papa") 300 times. In 15% of the trials, the subjects experienced a mechanical perturbation on the lower lip. Displacement and neural activation (EMG) of the upper and lower lips were evaluated. Perturbations to the lower lip caused a greater increase in the maximum displacement of the lower lip for older adults compared with young adults (34.7 ± 19% vs. 13.4 ± 17%; P=0.017). Furthermore, young adults exhibited significantly greater 30-100 Hz normalized EMG power for the lower lip compared to the upper lip (P<0.005). In young adults, changes from normal to perturbed trials in the 30-50 Hz frequency band of the EMG were negatively correlated to the changes from normal to perturbed trials in the lower lip maximum displacement (R (2) =0.48; P=0.025). It is concluded that young adults adapt better to lower lip perturbations compared with older adults and that the associated neural activation strategy of the involved muscle is different for the two age groups.

Comparing postural strategy changes following adapted versus non-adapted responses in subjects with and without spinal stenosis

Musculoskeletal evaluation skills are needed to examine postural compensation techniques, but little is known about ground reaction forces (GRF) in standing posture. Even though a number of studies have evaluated GRF in patients with low back pain (LBP) during vertical perturbations, it would be important to consider compensation characteristics which might be associated with abnormal patterns of postural responses. The vertical excursions of the body center of mass (BCOM) were measured with delay time and normalized amplitude of GRF. Overall, there was no difference based on the vertical excursion of the BCOM (F=0.12, p=0.90), amplitude of the normalized GRF (F=0.16, p=0.74), or response time (F=1.98, p=0.17) between subjects with and without spinal stenosis. There was a gender difference based on the vertical excursion of the normalized BCOM (F=5.92, p=0.02) as well as the normalized amplitude of GRF (F=4.17, p=0.04). It was shown that male subjects implemented better adjustment strategies during adapted and non-adapted responses in order to improve body stability. In this way, manual therapists should be aware that gender differences exist in patients with spinal stenosis since the condition may change the individual's postural adjustment ability.