Effect of trunk extensor fatigue on the postural balance of elderly and young adults during unipodal task

Assessing standing balance with MOTI: a validation study

OBJECTIVES

This study aimed to determine the validity and reliability of a new device called MOTI for measuring balance by comparing its performance that with of the gold-standard force platform.

METHODS

The study involved collecting data from both devices in dual- and single-leg standing positions with eyes open and closed and using statistical measures to compare their performance.

RESULTS

The results showed that MOTI can accurately measure balance during dual-leg standing tasks but has poor to moderate performance during single-leg standing tasks. However, it could detect small changes in postural sway caused by a reduced base of support and/or visual feedback. The study also found that the test-retest reliability was poor to moderate for both devices.

CONCLUSIONS

These findings suggest that MOTI has potential as a reliable tool for measuring balance during certain tasks, but further research is needed to improve its performance during single-leg standing. This study provides valuable insights into the validity and reliability of MOTI for measuring balance and highlights the need for further investigation.

Virtual reality skateboarding training for balance and functional performance in degenerative lumbar spine disease

BACKGROUND

Degenerative lumbar spine disease (DLD) is a prevalent condition in middle-aged and elderly individuals. DLD frequently results in pain, muscle weakness, and motor impairment, which affect postural stability and functional performance in daily activities. Simulated skateboarding training could enable patients with DLD to engage in exercise with less pain and focus on single-leg weight-bearing. The purpose of this study was to investigate the effects of virtual reality (VR) skateboarding training on balance and functional performance in patients with DLD.

METHODS

Fourteen patients with DLD and 21 age-matched healthy individuals completed a 6-week program of VR skateboarding training. The motion capture and force platform systems were synchronized to collect data during a single-leg stance test (SLST). Musculoskeletal simulation was utilized to calculate muscle force based on the data. Four functional performance tests were conducted to evaluate the improvement after the training. A Visual Analogue Scale (VAS) was also employed for pain assessment.

RESULTS

After the training, pain intensity significantly decreased in patients with DLD (p = 0.024). Before the training, patients with DLD took longer than healthy individuals on the five times sit-to-stand test (p = 0.024). After the training, no significant between-group differences were observed in any of the functional performance tests (p > 0.05). In balance, patients with DLD were similar to healthy individuals after the training, except that the mean frequency (p = 0.014) was higher. Patients with DLD initially had higher biceps femoris force demands (p = 0.028) but shifted to increased gluteus maximus demand after the training (p = 0.037). Gluteus medius strength significantly improved in patients with DLD (p = 0.039), while healthy individuals showed consistent muscle force (p > 0.05).

CONCLUSION

This is the first study to apply the novel VR skateboarding training to patients with DLD. VR skateboarding training enabled patients with DLD to achieve the training effects in a posture that relieves lumbar spine pressure. The results also emphasized the significant benefits to patients with DLD, such as reduced pain, enhanced balance, and improved muscle performance.

The automatic activity of abdominal muscles during stable and unstable standing postural tasks in older adults with and without low back pain- A cross-sectional study

BACKGROUND

The postural control and abdominal muscles' automatic activity were found to be impaired in subjects with low back pain (LBP) during static activities. However, the studies are predominantly conducted on younger adults and a limited number of studies have evaluated abdominal muscles' automatic activity during dynamic standing activities in subjects with LBP. The present study investigated the automatic activity of abdominal muscles during stable and unstable standing postural tasks in older adults with and without LBP.

METHODS

Twenty subjects with and 20 subjects without LBP were included. The thickness of the transversus abdominis (TrA), internal oblique (IO), and external oblique (EO) muscles was measured during rest (in supine), static, and dynamic standing postural tasks. To estimate automatic muscle activity, each muscle's thickness during a standing task was normalized to its thickness during the rest. Standing postural tasks were performed using the Biodex Balance System.

RESULTS

The mixed-model analysis of variance revealed that task dynamicity significantly affected thickness change only in the TrA muscle (P = 0.02), but the main effect for the group and the interaction were not significantly different (P > 0.05). There were no significant main effects of the group, task dynamicity, or their interaction for the IO and EO muscles (P > 0.05). During dynamic standing, only the TrA muscle in the control group showed greater thickness changes than during the static standing task (P < 0.05).

CONCLUSIONS

Standing on a dynamic level increased the automatic activity of the TrA muscle in participants without LBP compared to standing on a static level. Further research is required to investigate the effects of TrA muscle training during standing on dynamic surfaces for the treatment of older adults with LBP.

Concentrating to avoid falling: interaction between peripheral sensory and central attentional demands during a postural stability limit task in sedentary seniors

Evidence suggests falls and postural instabilities among seniors are attributed to a decline in both the processing of afferent signals (e.g., proprioceptive, vestibular) and attentional resources. We investigated the interaction between the non-visual and attentional demands of postural control in sedentary seniors. Old and young adults performed a postural stability limit task involving a maximal voluntary leaning movement with and without vision as well as a cognitive-attentional subtraction task. These tasks were performed alone (single-task) or simultaneously (dual-task) to vary the sensory-attentional demands. The functional limits of stability were quantified as the maximum center of pressure excursion during voluntary leaning. Seniors showed significantly smaller limits of postural stability compared to young adults in all sensory-attentional conditions. However, surprisingly, both groups of subjects reduced their stability limits by a similar amount when vision was removed. Furthermore, they similarly decreased their anterior-posterior stability limits when concurrently performing the postural and the cognitive-attentional tasks with vision. The overall average cognitive performance of young adults was higher than seniors and was only slightly affected during dual-tasking. In contrast, older adults markedly degraded their cognitive performance from the single- to the dual-task situations, especially when vision was unavailable. Thus, their dual-task costs were higher than those of young adults and increased in the eyes-closed condition, when postural control relied more heavily on non-visual sensory signals. Our findings provide the first evidence that as posture approaches its stability limits, sedentary seniors allot increasingly large cognitive attentional resources to process critical sensory inputs.

The Effect of Resist and Assist Torque of Hip Joint Motor-based Gait Assistance Robot on Gait Function in the Elderly

OBJECTIVES The purpose of this study was to investigate the effects of assist and resistance torque on the spatiotemporal gait characteristics, and the symmetry and asymmetry of gait using a Gait Enhancing and Motivating System (GEMS) in the elderly.METHODS A cross-sectional and repeated measure design was used. A total of 18 participants (9 males, 9 females; age: 63.5 ± 5.02 years; mass: 64.26 ± 6.87 kg; height: 164.06 ± 7.15 cm) were recruited from a local community, and spatiotemporal gait data were collected with OptoGait system and GEMS. Spatiotemporal gait variables and differences between the dominant and non-dominant legs of these variables were assessed (step length, step time, stance phase, swing phase, single support, load response, pre swing phase, stride time, stride length, double support, cadence, and gait speed). The effects of three modes including normal, assist, and resist modes using GEMS were investigated twice for each participant on a 9-meter walkway. A one-way repeated measure analysis of variance followed by Bonferroni post-hoc tests was conducted.RESULTS The assist mode increased step time, swing phase, stride time and reduced stance phase, pre-swing phase, double support, cadence, and gait speed as compared to normal mode. The resist mode increased stance phase, load response, pre-swing phase, double support, cadence, and reduced step time, swing phase, and stride time. In dominant leg, assist mode showed increased step time and reduced pre-swing phase than normal mode, and greater step time than resist mode (<i>p</i> < 0.05). However, there was no effect of external torque on symmetry and asymmetry between both legs (<i>p</i> > 0.05).CONCLUSIONS The resistance and assist torque of GEMS alter spatiotemporal characteristics during the stance and swing phase of gait in the elderly. However, the resistance torque and assist torque of GEMS did not increase or decrease the gait asymmetry between the dominant and non-dominant legs.

Immediate Effect of Lumbosacral Orthosis and Abdominal Drawing-In Maneuver on Postural Control in Adults With Nonspecific Chronic Low Back Pain

OBJECTIVE

The purpose of this study was to examine the immediate effects of lumbosacral orthosis and the abdominal drawing-in maneuver on the trunk postural control of adults with chronic low back pain compared with asymptomatic controls during 1-legged and semi-tandem stances.

METHODS

An experimental and comparative study (cross-sectional design) was conducted in a laboratory setting. Twenty adults with chronic low back pain and 20 asymptomatic controls randomly performed 2 postural balance tasks over a force platform, considering 3 experimental conditions: (1) natural posture (baseline-control), (2) lumbosacral orthosis, and (3) abdominal drawing-in maneuver. Linear variables (mean amplitude, ellipse area, and sway velocity) derived from the center of pressure were computed, and 2-way analysis of variance (group × condition) for repeated measures were conducted.

RESULTS

No group × condition interactions (.139 ≤ P ≤.938) were detected in any center of pressure parameters. No condition effect was detected, but a group effect (P = .042) was observed for 1 center of pressure parameter. The chronic low back pain group presented with a lower mean anteroposterior center of pressure amplitude than asymptomatic controls (∆ = 0.31 ± 0.66 cm [95% confidence interval, 0.05-0.56], P = .019) during the semi-tandem stance balance task.

CONCLUSION

Neither lumbosacral orthosis nor the abdominal drawing-in maneuver showed immediate improvement in trunk postural control in any group. Thus, clinicians should not expect immediate benefits or improvements yielded by lumbosacral orthosis or the abdominal drawing-in maneuver when patients with chronic low back pain undergo these interventions.

Physiological Mechanisms of Exercise and Its Effects on Postural Sway: Does Sport Make a Difference?

While the effect of a variety of exercises on postural balance control has been extensively studied, less attention has been paid to those requiring sport-specific skills. Therefore there is a need to analyze the literature and elucidate changes in postural balance control after exercises performed in conditions close to a particular sport. This scoping review aims (i) To map the literature that addresses postural sway aspects of acute responses to general and sport-specific exercises and their underlying physiological mechanisms, and (ii) To identify gaps in the existing literature and propose future research on this topic. The main literature search conducted on MEDLINE, Web of Science, Scopus, PubMed, and Cochrane Library databases was completed by SpringerLink, Elsevier, and Google Scholar. A total of 60 articles met the inclusion criteria. Findings identified that among a variety of studies evaluating the effects of exercise on postural balance control, only few of them were conducted under sport-specific conditions (i.e., while shooting in biathlon or pentathlon, and after simulated or match-induced protocols in combat and team sports). Therefore, more research is still needed to address this gap in the literature and aim research at investigation of postural sway response to sport-specific exercises. Further analysis of the literature showed that the type, intensity and duration of exercise play a key role in increased postural sway. Whole body and localized muscular fatigue of the trunk, neck and lower limbs is considered to be a main factor responsible for the magnitude of balance impairment in an initial phase of recovery and speed of its readjustment to a pre-exercise level. Other likely factors affecting postural stability are hyperventilation and deterioration of sensorimotor functions, though some contribution of muscle damage, dehydration, hyperthermia or dizziness cannot be excluded. A better understanding of the physiological mechanisms of balance impairment after exercises performed under simulated fatigue induced protocol, close to conditions specific to a particular sport, has implications for designing smart exercise programs tailored to individual needs to improve athlete performance with high demands on postural stability and/or decrease their risk of injuries.

Acute effect of core stability and sensory-motor exercises on postural control during sitting and standing positions in young adults

Core stability exercises and exercises that stimulate sensory-motor information are recommended for the prevention of injuries and the maintenance and rehabilitation of deficits related to postural control (PC). However, the comparison of results between core stability and sensory-motor exercises in the literature is limited to sitting and standing positions.

OBJECTIVE

To determine the acute effect of core stability and sensory-motor exercises on PC during sitting and standing in young adults.

METHODS

A total of 39 participants, with a mean age of 23 years, were randomly divided into three groups (1) Core stability exercises; (2) Sensory-motor exercises; (3) Control. Each group performed a sequence of five specific exercises of core stability and sensory-motor exercises (except controls). PC was evaluated before and after exercise in the seated and the one-legged stance conditions using a force platform.

RESULTS

No significant difference was found for any variables of postural oscillation (P > 0.05) among the three groups studied. The magnitude of the effect of interventions in general was a small to moderate effect (d = 0.02/-0.48).

CONCLUSION

The findings show that acute intervention with core stability and sensory-motor exercises did not produce any significant effects (reduction of postural oscillation) on PC during sitting and standing positions in young adults.

Effects of back extensor and hip abductor fatigue on dynamic postural stability in patients with nonspecific chronic low back pain: A case-control study

INTRODUCTION

Patients with nonspecific chronic low back pain (NSCLBP) complain of pain and fatigue during functional activities. Poor back muscle endurance has been associated with recurrent pain and long-term disability. However, the relationship between proximal muscle fatigue and postural stability is not well understood.

PURPOSE

To investigate the effects of lumbar extensor and hip abductor fatigue on postural stability in NSCLBPs.

METHODS

To induce isolated fatigue, participants (24 LBPs, 24 controls) were asked to perform multiple back extension and hip abduction in the separate sessions until the muscle force reached 60% of pre-fatigued force. The overall (OSI), anteroposterior (APSI), and mediolateral (MLSI) stability indices were measured during single-leg stance using the Biodex dynamic platform.

RESULTS

The results revealed higher postural instability (APSI and OSI) following fatiguing lumbar extensor and hip abductor muscles (greater effect size for APSI than OSI) in LBPs than controls. Furthermore, significant and inverse relationships were found between the level of physical activity, pain, and post-fatigue postural instability (OSI) in NSCLBPs.

CONCLUSION

Fatigue of proximal muscles could differentiate postural stability primarily in the sagittal plane between NSCLBPs and controls. Therefore, reducing the fatigability of these muscles by endurance training in addition to balance training may improve physical activity.

Impact of Prolonged Exposure to a Slippery Surface on Postural Stability

Falls are extremely common in occupational settings. Intrinsic factors such as overexertion and extrinsic factors such as the supporting surface are causative factors of falls. The impact of prolonged exposure to a slippery surface on postural stability has not been previously studied. The purpose of the study was to analyze the effect of extended exposure to a dry and a slippery surface on postural stability. Eighteen males (age: 21.17 ± 3.38 years; height: 1.77 ± 0.08 m; mass: 89.81 ± 14.23 kg) were recruited and subjected to one-hour walking on a dry surface and a slippery surface on two different days. Participants’ balance was assessed using a force platform in stable and unstable conditions at 0, 30, and 60 min. Postural sway variables were analyzed using a 2 (surface) × 3 (time) repeated-measures ANOVA. Significant time main effects were observed in the stable condition with greater balance decrements at 30 and 60 min. Greater balance decrements were observed on the slippery surface compared to the dry surface in the unstable condition. The balance decrements can be attributed to overexertion due to the physiological workload of prolonged walking and to the potential gait modifications due to walking on the slippery surface.

Acute Effects of Single- Versus Double-Leg Postactivation Potentiation on Postural Balance of Older Women: An Age-Matched Controlled Study

AIMS

To compare the postactivation potentiation effects of isometric contraction until failure in double- and single-leg tasks on older women's balance.

METHODS

The one-legged balance test was performed before and immediately after a rise-to-toes task until the task failure. Older women were divided into two groups: a group performed the task with double leg (n = 43) and the other group with single-leg support (n = 55).

RESULTS

The single-leg group showed slower velocity of sway post rise-to-toes task (pre = 4.02 ± 1; post = 3.78 ± 1.15 m/s; p = .04) without differences for the center of pressure path length (pre = 79 ± 21; post = 75 ± 23 cm; p = .08). In the double-leg group, faster velocity of sway (pre = 4 ± 1.22; post = 4.25 ± 1.13; p = .03) and increased center of pressure path length (pre = 80 ± 24; post = 85 ± 23 cm; p = .03) were observed after the task.

CONCLUSIONS

The single-leg group showed improved balance outcomes due to postactivation potentiation, while the double-leg group showed worsened balance consistent with muscle fatigue.

Effects of lumbar stabilization and muscular stretching on pain, disabilities, postural control and muscle activation in pregnant woman with low back pain

BACKGROUND

Low back pain is common during pregnancy. Lumbar stabilization and stretching exercises are recommended to treat low back pain in the general population. However, few studies have applied the effects of these two interventions in pregnant women with low back pain.

AIM

To compare the effects of lumbar stabilization and stretching exercises for the treatment of gestational low back pain.

DESIGN

A pilot randomized clinical trial.

SETTING

Laboratory of Functional Evaluation and Human Motor Performance and physical therapy clinics.

POPULATION

Initially, 30 pregnant women with low back pain were recruited, of which 24 met the following inclusion criteria: being between 19-29 weeks of gestation; being in prenatal clinical follow-up; having nonspecific mechanical low back pain started in pregnancy; not participating in specific low back pain treatment in the last 3 months. A total of 20 women completed the study (10 each group).

METHODS

The main outcome measures were clinical (pain by Visual Analogue Scale (VAS) and McGill Pain Questionnaire and disability by Roland Morris Questionnaire), and secondary outcome measures were: postural balance (force platform); muscle activation level of multifidus, iliocostalis lumborum, rectus abdominis and external abdominal oblique (electromyography). The women were randomized into two groups for 6 weeks of intervention twice a week for a 50-minute treatment: 1) lumbar stabilization exercise protocol and 2) stretching exercise protocol.

RESULTS

There was a significant reduction (P=0.03) in pain (1.68 in VAS and 4.81 for McGill questionnaire) for both interventions, but no change in disability score. In addition, both interventions were comparable for a significant improvement in postural stability (in mean d=0.77) for the velocity sway parameter, and significantly increased activation (P>0.05) of the external abdominal oblique muscle after intervention.

CONCLUSIONS

Both modalities (lumbar stabilization and stretching) were efficient for pain reduction, improving balance and increasing one trunk activity muscle after 6 weeks of intervention in pregnant women with low back pain.

CLINICAL REHABILITATION IMPACT

The present study has implications, especially for clinical decision-making with regard to therapy choice in pregnant women with LBP to reduce pain and improve trunk function as measured through balance performance.

Influence of Textured Indoor Footwear on Posture Stability of Older Women Based on Center-of-Pressure Measurements

OBJECTIVE

The objective of this study is to evaluate the efficacy of indoor footwear with a textured surface to improve control of balance and reduce excessive plantar pressure in older women.

BACKGROUND

Balance instability is a common condition in older people. Textured insoles with protrusions on the entire insole have been examined for enhancing somatosensory feedback in the elderly to improve control over balance. However, these insoles have significant challenges in distributing the plantar pressure. Textured insoles with tailored protrusions should be therefore investigated for the same purpose but provide better plantar pressure distribution.

METHOD

A total of 24 older women have undergone both static standing and walking tests with the use of the in-shoe Pedar® system.

RESULTS

The results indicate that wearing textured indoor footwear provides a significant reduction in postural sway, particularly in the medial-lateral direction during walking. As compared to walking barefoot, the center-of-pressure trajectory when wearing the textured indoor footwear remains supported with less variance among the steps, which is statistically significant in the medial-lateral direction. A significant reduction in the peak pressure is found in the forefoot and rearfoot regions as the plantar pressure is redistributed to the midfoot regions.

CONCLUSION

The textured surface of the insole improves balance control of older women and effectively reduces foot pressure at high pressure areas.

APPLICATION

The findings enhance current understanding on textured footwear as a form of intervention associated with changes in functional impairments, therefore providing basis for footwear design in balance control.

Short-term effect of delayed-onset muscle soreness on trunk proprioception during force reproduction tasks in a healthy adult population: a crossover study

PURPOSE

The aim of this study was to evaluate the effects of lumbar muscle delayed-onset muscle soreness (DOMS) on the ability of the trunk muscles to reproduce different levels of force.

METHODS

Twenty healthy adults (10 males and 10 females) were recruited for this study. Force reproduction in trunk extension and flexion was assessed at 50 and 75% of participants' maximal isometric voluntary contraction in flexion and extension before and after a lumbar muscle DOMS protocol. Trunk proprioception was evaluated and compared between these conditions using different variables such as constant errors (CE), absolute errors (AE), variable errors (VE) and time to peak force (TPF). For each variable, repeated measure ANOVAs were conducted.

RESULTS

AE were higher when participants had to reach the target post-DOMS protocol in extension compared to flexion and in the presence of higher demand of force (p = 0.02). For VE, results showed that participants were more variable in extension than in flexion when the required force was higher (p = 0.04). CE variable was higher when participants had to reach the force target in extension compared to flexion under the effect of DOMS (p = 0.02). Results also showed that participants took less time to reach the force target post-DOMS protocol in extension (0.62 ± 0.20 s) and in flexion (0.53 ± 0.19 s) than pre-DOMS protocol in extension (0.55 ± 0.15) and in flexion (0.50 ± 0.20) (p < 0.001).

CONCLUSION

Lumbar muscle DOMS affects trunk proprioception during force reproduction tasks especially in trunk extension and at higher force.

The effects of different attentional focus on poststroke gait

Attention may influence the motor performance of poststroke patients. The attentional focus implies “where” attention is focused while performing a specific movement. Focusing attention on the inside of the body while performing a specific exercise is called an internal focus (IF) and focus on the external environment is called an external focus (EF). This study examined the effect of attention on the gait of patients with chronic stroke. Sixteen subjects voluntarily participated in the study. The subjects were guided to walk while maintaining the required attentional focus, which is control, IF, and EF condition. Dependent variables were as follows: step length, stride length, step width, 10-m walk time, and weight distribution on the paretic limb. The results are as follows. First, the step length and the stride length were observed to be longer in the EF condition. Second, 10-m walk time was faster in EF condition. Third, under the EF condition, more weight was applied to the paretic limb. We suggest that EF instruction useful to improve the poststroke gait.

Changes of balance control in individuals with lumbar degenerative spine disease after lumbar surgery: a longitudinal study

BACKGROUND CONTEXT

Lumbar degenerative spine disease (DSD) with neurological symptoms is the most common indication requiring lumbar surgery when nonoperative treatment is not effective. Individuals with lumbar DSD have sensory, proprioception, and musculoskeletal system alterations, which may result in balance impairment. However, evidence regarding balance recovery in individuals with lumbar DSD after lumbar surgery is limited.

PURPOSE

To evaluate balance control, pain, and functional activities in individuals with lumbar DSD after lumbar surgery.

STUDY DESIGN/SETTING

A prospective study with a cross-sectional control group.

PATIENT SAMPLE

Seventy individuals with lumbar DSD (DSD group) and 30 age-matched healthy adults (control group) were recruited. Participants in the DSD group were diagnosed by a neurological surgeon and received lumbar surgery according to relevant imaging findings and neurological symptoms.

OUTCOME MEASURES

Clinical assessments, including a visual analogue scale (VAS), the Oswestry Disability Index (ODI), and the Roland-Morris Disability Questionnaire (RMDQ), were performed in the DSD group only. Balance control was assessed in all participants using the root mean square (RMS) distance of the center of pressure (COP) in anteroposterior and mediolateral directions.

METHODS

All participants were instructed to stand in natural stance and Romberg stance with eyes open and eyes closed on a force platform for 35 seconds, respectively. The assessments were performed in the DSD group at four time points: preoperative phase (baseline), 3 months, 6 months, and 12 months postoperatively. In the age-matched healthy control group, only one assessment on the recruitment day was performed.

RESULTS

The VAS, ODI, and RMDQ scores of the DSD group significantly improved after lumbar surgery (p<.001). The RMS distance of COP in the DSD group significantly decreased after lumbar surgery (p<.017) compared with baseline in most of the testing conditions. However, the RMS distance of the COP in the DSD group after surgery was significantly greater than in the healthy control group (p<.05), especially 6 months and 12 months postoperatively.

CONCLUSIONS

Balance control, pain, and functional activities of individuals with lumbar DSD showed improvement after lumbar surgery. However, balance control in individuals with lumbar DSD was still less stable than in age-matched healthy adults from 6 to 12 months after surgery. Therefore, individuals with lumbar DSD require fall prevention programs after lumbar surgery, including balance assessments and postoperative balance training.

The effect of trunk muscle fatigue on postural control of upright stance: A systematic review

BACKGROUND

Fatigability and postural control deficits are both serious concerns in a variety of chronic musculoskeletal conditions. Research has shown that muscle fatigue may adversely affect postural control. This is while the evidence on the relevance of fatigue to postural control has never been summarized nor critically appraised.

RESEARCH QUESTION

Is there sufficient and strong enough evidence to accept trunk muscle fatigue as a contributing factor to postural control alterations during upright standing posture?.

METHODS

EMBASE, Scopus, ELSEVIER, PubMed, ProQuest, Google scholar and reference lists of the relevant articles were searched through April 2018. Studies having investigated the trunk muscle fatigue effect on postural control in asymptomatic individuals were included in the study. Only those studies having assessed postural control in terms of center of pressure driven variables were included.

RESULTS

Twelve studies (218 asymptomatic participants) matched the inclusion criteria of this systematic review. Their results supported the hypothesis that fatigue has a significant effect on postural control in terms of the time domain variables. Sway velocity was consistently found to be affected by fatigue. The results were inconsistent in the frequency domain. The only study on the structural dynamics of center of pressure displacements also confirmed such a relationship.

SIGNIFICANCE

The present review indicates that postural control is altered in asymptomatic individuals following trunk muscle fatigue. This may suggest that trunk muscle endurance training is crucial to address postural impairment in chronic spine musculoskeletal conditions.

Impact of Lifting of Two Types of Barrels on Postural Control, Trunk Muscle Recruitment, and Kinematic Measures in Manual Workers

The aim of this study was to evaluate the impact of 2 types of beer barrels on postural control, trunk activation, and kinematic measures in adult workers. Twelve (12) males randomly performed 4 tasks on a force platform for 20 s: (1) hold an empty recyclable barrel, (2) hold a full recyclable barrel (30 L), (3) hold an empty steel barrel, and (4) hold a full steel barrel (30 L). Trunk muscular activation, force platform and kinematic measures at the trunk, hip, and knee joints were computed. The full steel barrel produced greater postural oscillation than other conditions. Higher trunk activity was also reported during the full steel barrel task. Significant kinematic changes only in the trunk were observed between the empty steel barrel and the full recyclable barrel tasks. In conclusion, the full steel barrel produced a negative impact on postural control, increasing trunk activity and changing trunk flexion angle in adult workers.

Age- and low back pain-related differences in trunk muscle activation during one-legged stance balance task

BACKGROUND

Postural control declines with age and can be affected by low back pain. Poor balance has been reported in people with chronic low back pain (CLBP), which in turn could be explained by the changes in trunk muscle activation.

RESEARCH QUESTION

Are there differences between younger and older adults with and without chronic low back pain (CLBP) on trunk muscle activity during one-legged stance task?

METHODS

Twenty (20) with, and 20 subjects without nonspecific CLBP participated in the study. Each group was comprised of 10 younger (50% males; mean age: 31 years) and 10 older adults (50% males; mean age: 71 years). Subjects performed 3 × 30-second trials of one-legged stance, with eyes open, on a force platform, while surface electromyography (EMG) measurements were obtained bilaterally on the multifidus at L5, iliocostalis lumborum at L3, rectus abdominis and biceps femoris muscles.EMG amplitude analysis was processed by the Root Mean Square (250 ms window epochs) and normalized by the peak of activation during the balance tasks, to determine the muscular activity of each muscle.

RESULTS

Participants with CLBP presented 15% lower lumbar muscle activation (p <  0.05), and 23% higher co-activation (ratio between rectus adominis by multifidus) than participants without CLBP, regardless of age. Significant differences (p <  0.05) between older and young groups were observed only for lower lumbar muscles (mean 24% lower in older than younger adults) and rectus adominis muscles (mean 17% lower in older than younger adults).

SIGNIFICANCE

CLBP individuals have different trunk muscle activity than those without CLBP, and older adults exhibit lower trunk activation during one-legged stance balance task. The use of the EMG in evaluation of trunk neuromuscular function during one-legged stance may thus be a valuable tool when assessing balance in CLBP and older people.

Effects of Volume Training on Strength and Endurance of Back Muscles: A Randomized Controlled Trial

CONTEXT

Strength/resistance training volume has historically been supported in the American College of Sports Medicine recommendations. However, for the back muscles, exercise prescription related to the number of sets, such as single versus multiple, is not well established in the literature.

OBJECTIVE

The purpose of this study was to compare the effects of 2 training volumes on strength and endurance of back-extensor muscles in untrained young participants with regard to a repeated-measures design.

DESIGN

Randomized controlled trial.

SETTING

Laboratory of functional evaluation and human motor performance.

PARTICIPANTS

Forty-four untrained young participants (mean age = 21 y) were randomized into single-set (n = 14), multiple-set (MSG, n = 15), and untrained control (n = 15) groups.

INTERVENTION

The single-set group and MSG underwent a 10-week progressive resistance training program (2 d/wk) using a 45° Roman chair.

MAIN OUTCOME MEASURES

Back maximal strength (dynamometer) and isometric and dynamic endurance (time limit, trunk extension-flexion cycles, and electromyography muscle fatigue estimates).

RESULTS

The results showed differences between the MSG and control group for isometric endurance time (mean = 19.8 s; 95% confidence interval, -44.1 to 4.8), but without time intervention significance. Significant improvement after training (P < .05) was found predominantly during dynamic endurance (number of repetitions) for both the MSG (+61%) and single-set group (+26%) compared with preintervention, whereas the control group reported no benefit. There was no significant (P > .05) difference in either strength or electromyography estimates after training.

CONCLUSIONS

Both multiple and single volume training were efficient in promoting better back endurance during dynamic performance based on mechanical variables (time and number of repetitions).

Postural control and physiological responses to a simulated match in U-20 judo competitors

The aim was to evaluate the effects of judo combat on the athletes' postural control (PC) and physiological loading before, during and after a simulated match. Seventeen under-20 regional and national level athletes completed one modified 7-min match. At baseline, during the combat (3rd and 7th minutes) and 2-min post-match centre of pressure (CoP) parameters were assessed. Heart rate (HR), blood lactate (BLa) and rating of perceived exertion (RPE) and local RPE (LRPE) were collected. Significant increments were observed in CoP mean positioning and velocity at 3rd and 7th minutes, but the CoP deviation in both axes was unaffected. HR and BLa were elevated at 3rd and 7th minutes, and they remained elevated 2-min post-match. However, CoP returned to baseline 2-min post-match. RPE was elevated at 3rd and 7th minutes and the greatest effort was displayed in the Deltoid and Quadriceps. Thus, one simulated judo match stimulates a significant metabolic response and balance is degraded, with the greatest effects on the anterior-posterior axis and it recovers to baseline level after 2 min of passive rest. The physiological load cannot be regarded as a potential predictor variable of CoP. Overall, a judo match predominantly affects the upper body than the other body parts.

Reliability of the Kinematic Steadiness Index during one-leg standing in subjects with recurrent low back pain

PURPOSE

To assess the reliability of standing time and the Kinematic Steadiness Index (KSI) in one-leg standing compared with the Timed Up and Go (TUG) test while considering anthropometric factors in subjects with recurrent low back pain (LBP).

METHODS

Sixty-six individuals participated in the study. The data were collected on two different days, 1 week apart. The KSI of the core spine, using video motion-capture techniques, was based on the relative standing time and relative standstill time. The intraclass correlation coefficient (ICC_2,1) was compared for the reliability between measures. The covariates, such as age, Body Mass Index, and the Oswestry Disability Index (ODI), were analyzed for any interactions based on these measures.

RESULTS

The standing time (t = - 1.01, p = 0.32) and the KSI (t = - 1.70, p = 0.09) were not significantly different between measures. The TUG results were not different between measures (t = 1.01, p = 0.32). The Cronbach's alpha for the standing time was 0.84, for KSI was 0.89, and for TUG was 0.76. The standing time and KSI demonstrated an interaction with age, while the TUG demonstrated an interaction with the ODI score.

CONCLUSIONS

The KSI during one-leg standing could help to develop a practical tool to justify quantity and quality of balance outcome measures, which identify balance deficits and core spine rehabilitation strategies in subjects with recurrent LBP.

Comparação do controle postural em cinco tarefas de equílibrio e a relação dos riscos de quedas entre idosas e adultas jovens

RESUMO O envelhecimento é um processo natural que acarreta mudanças intrínsecas e extrínsecas ao organismo. O objetivo é analisar cinco tarefas de equilíbrio postural em idosas através da Plataforma de força, correlacionando com o risco de quedas avaliado pelo teste Timed Up and Go (TUG). Participaram do estudo 43 idosos e 40 adultos jovens, todos do sexo feminino, que foram avaliadas em uma plataforma de força com um protocolo padrão: descalças, com os braços ao longo do corpo nas tarefas bipodal e semitandem, ambos olhos abertos e fechados, apoio unipodal utilizando o centro de oscilação postural (COP) e as velocidades nos eixos anteroposterior (Vel AP) e médio-lateral (Vel ML). Após 5 minutos de descanso, realizou-se o TUG. Os resultados mostraram que as idosas tiveram maior instabilidade postural (p<0.05) em relação às adultas jovens, e a tarefa que mais desafiou o equilíbrio foi o apoio unipodal COP 10,02 (cm2) Vel AP 3,00 (cm/s) e Vel ML 3,32 (cm/s), e as idosas tiveram um tempo médio no TUG de 9,01 segundos considerando um baixo risco de quedas. Conclusão: Idosas apresentam um maior déficit no equilíbrio em relação às jovens, sendo a tarefa de apoio UNP a que mais apresentou desafios no controle postural das duas populações. Idosas saudáveis apresentaram um baixo risco para as quedas, nenhuma correlação foi encontrada entre o equilíbrio postural através da plataforma de força e risco de quedas do TUG.

Effects of Holding an External Load on the Standing Balance of Older and Younger Adults With and Without Chronic Low Back Pain

OBJECTIVE

The purpose of this study was to assess the effect of holding an external load on the standing balance of younger and older adults with and without chronic low back pain (CLBP).

METHODS

Twenty participants with and 20 without CLBP participated in the study. Each group contained 10 younger (50% men) and 10 older adults (50% men). Participants were instructed to look straight ahead while standing on a force platform during two 120-second trials with and without holding an external load (10% of body mass). The center of pressure area, mean velocity, and mean frequency in the anteroposterior and mediolateral directions were measured.

RESULTS

Older adults had worse standing balance than younger adults did (P < .001, d = 0.20). There were no significant balance differences between participants with and without CLBP within age groups during standing balance condition. However, holding the external load significantly increased postural instability for both age groups and CLBP status, with mean effect size across center of pressure variables of d = 0.82 for older participants without CLBP and d = 2.65 for younger participants without CLBP. These effects for people with CLBP were d = 1.65 for subgroup of older and d = 1.60 for subgroup of younger participants.

CONCLUSION

Holding an external load of 10% of body mass increased postural instability of both younger and older adults with and without CLBP.

People with chronic low back pain have poorer balance than controls in challenging tasks

PURPOSE

To compare the balance of individuals with and without chronic low back pain during five tasks.

METHOD

The participants were 20 volunteers, 10 with and 10 without nonspecific chronic low back pain, mean age 34 years, 50% females. The participants completed the following balance tasks on a force platform in random order: (1) two-legged stance with eyes open, (2) two-legged stance with eyes closed, (3) semi-tandem with eyes open, (4) semi-tandem with eyes closed and (5) one-legged stance with eyes open. The participants completed three 60-s trials of tasks 1-4, and three 30-s trials of task 5 with 30-s rests between trials. The center of pressure area, velocity and frequency in the antero-posterior and medio-lateral directions were computed during each task, and compared between groups and tasks.

RESULTS

Participants with chronic low back pain presented significantly larger center of pressure area and higher velocity than the healthy controls (p < 0.001). There were significant differences among tasks for all center of pressure variables (p < 0.001). Semi-tandem (tasks 3 and 4) and one-leg stance (task 5) were more sensitive to identify balance impairments in the chronic low back pain group than two-legged stance tasks 1 and 2 (effect size >1.37 vs. effect size <0.64). There were no significant interactions between groups and tasks.

CONCLUSIONS

Individuals with chronic low back pain presented poorer postural control using center of pressure measurements than the healthy controls, mainly during more challenging balance tasks such as semi-tandem and one-legged stance conditions. Implications for Rehabilitation People with chronic low back had poorer balance than those without it. Balance tasks need to be sensitive to capture impairments. Balance assessments during semi-tandem and one-legged stance were the most sensitive tasks to determine postural control deficit in people with chronic low back. Balance assessment should be included during rehabilitation programs for individuals with chronic low back pain for better clinical decision making related to balance re-training as necessary.

The Effects of Performance Fatigability on Postural Control and Rehabilitation in the Older Patient

Fatigue is common in older adults and has a significant effect on quality of life. Despite the high prevalence of fatigue in older individuals, several aspects are poorly understood. It is important to differentiate subjective fatigue complaints from fatigability of motor performance because the two are independent constructs with potentially distinct consequences on mobility. Performance fatigability is the magnitude of change in a performance criterion over a given time of task performance. Performance fatigability is a compulsory element of any strength training program, yet strength training is an important component of rehabilitation programs for older adults. The consequences of fatigability for older adults suggest that acute exercise of various types may result in acute impairments in postural control. The effects of performance fatigability on postural control in older adults are evaluated here to aid the rehabilitation clinician in making recommendations for evaluation of fall risks and exercise prescription.

Effects of age and acute muscle fatigue on reactive postural control in healthy adults

BACKGROUND

Falls can cause moderate to severe injuries such as hip fractures and head trauma in older adults. While declines in muscle strength and sensory function contribute to increased falls in older adults, skeletal muscle fatigue is often overlooked as an additional contributor to fall risk. The purpose of this investigation was to examine the effects of acute lower extremity muscle fatigue and age on reactive postural control in healthy adults.

METHODS

A sample of 16 individuals participated in this study (8 healthy older adults and 8 healthy young persons). Whole body kinematic and kinetic data were collected during anterior and posterior reproducible fall tests before (T0) and immediately after (T1) eccentric muscle fatiguing exercise, as well as after 15-min (T15) and 30-min (T30) of rest.

FINDINGS

Lower extremity joint kinematics of the stepping limb during the support (landing) phase of the anterior fall were significantly altered by the presence of acute muscle fatigue. Step velocity was significantly decreased during the anterior falls. Statistically significant main effects of age were found for step length in both fall directions. Effect sizes for all outcomes were small. No statistically significant interaction effects were found.

INTERPRETATION

Muscle fatigue has a measurable effect on lower extremity joint kinematics during simulated falls. These alterations appear to resolve within 15 min of recovery. The above deficits, coupled with a reduced step length, may help explain the increased fall risk in older adults.

Effects of two exercise protocols on postural balance of elderly women: a randomized controlled trial

BACKGROUND

The aging process reduces both sensory capabilities and the capabilities of the motor systems responsible for postural control, resulting in a high number of falls among the elderly. Some therapeutic interventions can directly interrupt this process, including physical exercise. This study compares and examines the effects of two exercise protocols on the balance of elderly women.

METHODS

Elderly women who participated in a local church project (n = 63) were randomly divided into three groups: the proprioceptive neuromuscular facilitation group (PNFG), Pilates group (PG), and control group (CG). Of the 63 women, 58 completed the program. A training program involving 50-min sessions was performed in the PNFG and PG three times a week for 4 weeks. The elderly women in the CG received no intervention and continued with their daily activities. Stabilometric parameters, the Berg Balance Scale score, functional reach test, and timed up and go test (TUG test) were assessed before and 1 month after participation.

RESULTS

In the comparison among groups, the women in the PNFG showed a significant reduction in most of the stabilometric parameters evaluated and better Berg Balance Scale score, functional reach test result, and TUG test result than did women in the CG (p < 0.05). Women in the PG showed significantly better performance on the functional reach test and TUG test than did women in the CG (p < 0.05).

CONCLUSIONS

Women in the PNFG showed significantly better static and dynamic balance than did women in the CG. Women in the PG also showed better dynamic balance than did women in the CG. However, no significant differences were observed in any of the balance variables assessed between the PNFG and PG.

TRIAL REGISTRATION

clinicaltrials.gov, number NCT02278731.

The impact of a submaximal level of exercise on balance performance in older persons

Objective. The purpose of this study was to determine the impact of a submaximal level of exercise on balance performance under a variety of conditions. Material and Method. Thirteen community-dwelling older persons with intact foot sensation (age = 66.69 ± 8.17 years, BMI = 24.65 ± 4.08 kg/m², female, n = 6) volunteered to participate. Subjects' balance performances were measured using the Modified Clinical Test of Sensory Integration of Balance (mCTSIB) at baseline and after test, under four conditions of stance: (1) eyes-opened firm-surface (EOF), (2) eyes-closed firm-surface (ECF), (3) eyes-opened soft-surface (EOS), and (4) eyes-closed soft-surface (ECS). The 6-minute walk test (6MWT) protocol was used to induce the submaximal level of exercise. Data was analyzed using the Wilcoxon Signed-Rank Test. Results. Balance changes during EOF (z = 0.00, P = 1.00) and ECF (z = −1.342, P = 0.180) were not significant. However, balance changes during EOS (z = −2.314, P = 0.021) and ECS (z = −3.089, P = 0.02) were significantly dropped after the 6MWT. Conclusion. A submaximal level of exercise may influence sensory integration that in turn affects balance performance, particularly on an unstable surface. Rehabilitation should focus on designing intervention that may improve sensory integration among older individuals with balance deterioration in order to encourage functional activities.

Trunk extensor fatigue decreases jump height similarly under stable and unstable conditions with experienced jumpers

PURPOSE

The purpose of this study was to investigate the effects of back extensor fatigue on performance measures and electromyographic (EMG) activity of leg and trunk muscles during jumping on stable and unstable surfaces.

METHODS

Before and after a modified Biering-Sorensen fatigue protocol for the back extensors, countermovement (CMJ) and lateral jumps (LJ) were performed on a force plate under stable and unstable (balance pad on the force plate) conditions. Performance measures for LJ (contact time) and CMJ height and leg and trunk muscles EMG activity were tested in 14 male experienced jumpers during 2 time intervals for CMJ (braking phase, push-off phase) and 5 intervals for LJ (-30 to 0, 0-30, 30-60, 60-90, and 90-120 ms) in non-fatigued and fatigued conditions.

RESULTS

A significant main effect of test (fatigue) (p = 0.007, f = 0.57) was observed for CMJ height. EMG analysis showed a significant fatigue-induced decrease in biceps femoris and gastrocnemius activity with CMJ (p = 0.008, f = 0.58 andp = 0.04, f = 0.422, respectively). LJ contact time was not affected by fatigue or surface interaction. EMG activity was significantly lower in the tibialis anterior with LJ following fatigue (p = 0.05, f = 0.405). A test x surface (p = 0.04, f = 0.438) interaction revealed that the non-fatigued unstable CMJ gastrocnemius EMG activity was lower than the non-fatigued stable condition during the onset-of-force phase.

CONCLUSION

The findings revealed that fatiguing the trunk negatively impacts CMJ height and muscle activity during the performance of CMJs. However, skilled jumpers are not additionally affected by a moderately unstable surface as compared to a stable surface.