The effect of inspiratory muscles fatigue on postural control in people with and without recurrent low back pain

The effect of acute respiratory demand on postural control: A systematic review

BACKGROUND

Postural control can be challenged by breathing.

RESEARCH QUESTION

What is the effect of an acute increase in respiratory demand on postural control compared to quiet breathing?

METHODS

A systematic review was conducted. Electronic databases were systematically searched until October 18, 2022 on studies reporting changes in center of pressure (CoP) motion related to an acute manipulation of respiratory demand compared to quiet breathing during upright standing in healthy participants and/or participants with a clinical condition.

RESULTS

Twenty-one studies in healthy participants showed that voluntary (not metabolic-induced) hyperventilation or inspiratory resistive loading significantly increased CoP motion, while breath-holding decreased CoP motion, compared to quiet breathing (p< 0.05). Manipulating respiratory rate or breathing patterns did not reveal consistent results. Four studies showed that people with low back pain showed similar CoP responses to increasing respiratory demand (p> 0.05), except for breathing at different rates, whereas they showed greater CoP motion during quiet breathing.

SIGNIFICANCE

The extent of postural disturbance depended on the breathing mode and how it was quantified (i.e., CoP coupled with breathing movement or overall CoP measures). Voluntary hyperventilation and inspiratory resistive loading increased postural sway. For voluntary hyperventilation, this could be explained by CoP motion being directly coupled to chest wall movements whereas metabolic-induced hyperventilation did not increase CoP motion or CoP coupling with breathing. Breath-holding decreased postural sway. Patients with low back pain show greater postural sways than pain-free individuals during quiet breathing, although they exhibit similar postural adaptations to respiratory-related challenges as controls.

Functional Sitting Balance and Anthropometric Measures Are Related to Inspiratory Muscle Performance in People with Spinal Cord Injury

Background

Respiratory complications are a leading cause of mortality post spinal cord injury (SCI). Along with breathing, respiratory muscles have a role in maintaining seated balance. Postinjury breathing influences respiratory muscle function. Preliminary evidence indicates a relation between respiratory muscle function and seated balance in people with chronic SCI dwelling in the community, but the relationship between balance and body habitus has not been explored.

Objectives

To explore the relationships among inspiratory muscle function, functional seated balance (FSB), and body habitus in people with SCI.

Methods

A convenience sample of inpatients with SCI (C5-T12) aged 18 to 60 years who were using a wheelchair was recruited from November 2022 to March 2023. Those with additional neurological disorders or respiratory support were excluded. Respiratory muscle function measures included maximal inspiratory pressure (MIP), sustained MIP (SMIP), and Fatigue Index Test (FIT). FSB was scored using the Function in Sitting Test (FIST). Body habitus was assessed using the axillary: umbilical (A:U) ratio. Spearman correlations explored the relationships.

Results

Thirty-eight of 42 screened participants were eligible and participated (male, 32). Levels of injury ranged from C5 to T12. The mean (SD) age and duration of injury of the sample was 25.61 (6.68) years and 31.03 (28.69) months, respectively. SMIP and FIT correlated significantly with FSB (r s= .441, p = .01, and r s= .434, p = .006, respectively). A significant correlation between SMIP and A:U ratio (r s= -.330, p = .043) was observed.

Conclusion

We observed a significant correlation between inspiratory pressure parameters and both functional seated balance and body habitus, adding to evidence on postural role of respiratory muscles.

Influence of an inspiratory muscle fatigue protocol on healthy youths on respiratory muscle strength, vertical jump performance and muscle oxygen saturation: a randomized controlled trial

BACKGROUND

Inspiratory muscle fatigue has been shown to have effects on limbs blood flow and physical performance. This study aimed to evaluate the influence of an inspiratory muscle fatigue protocol on respiratory muscle strength, vertical jump performance and muscle oxygen saturation in healthy youths.

METHODS

A randomized and double-blinded controlled clinical trial, was conducted. Twenty-four participants aged 18-45 years, non-smokers and engaged in sports activity at least three times a week for a minimum of one year were enrolled in this investigation. Participants were randomly assigned to three groups: Inspiratory Muscle Fatigue (IMFG), Activation, and Control. Measurements of vertical jump, diaphragmatic ultrasound, muscle oxygen saturation, and maximum inspiratory pressure were taken at two stages: before the intervention (T1) and immediately after treatment (T2).

RESULTS

The IMFG showed lower scores in muscle oxygen saturation and cardiorespiratory variables after undergoing the diaphragmatic fatigue intervention compared to the activation and control groups (p < 0.05). For the vertical jump variables, intragroup differences were found (p < 0.01), but no differences were shown between the three groups (p > 0.05).

CONCLUSIONS

Inspiratory muscle fatigue appears to negatively impact vertical jump performance, muscle oxygen saturation and inspiratory muscle strength in healthy youths.

TRIAL REGISTRATION

ClinicalTrials.gov ID: NCT06271876. Date of registration 02/21/2024. https://clinicaltrials.gov/study/NCT06271876 .

Effects of breathing exercises on chronic low back pain: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

A range of studies concerning the effects of breathing exercises on chronic low back pain (CLBP) have been proven inconclusive.

OBJECTIVE

The study aimed to evaluate the effectiveness of breathing exercises for the treatment of CLBP.

METHODS

We considered randomized controlled trials in English or Chinese that used breathing exercises for the treatment of CLBP. An electronic search was performed in the MEDLINE, EMBASE, Web of Science, Cochrane Library, CNKI, Wan Fang, and CBM databases for articles published up to November 2022. Two reviewers independently screened the articles, assessed the risk of bias using the Cochrane risk of bias tool, and extracted the data. The outcomes included pain, lumbar function and pulmonary function post-intervention.

RESULTS

A total of thirteen studies (n= 677) satisfied the inclusion criteria. The meta-analysis results demonstrated a significant effect of breathing exercises on the Visual Analog Scale (VAS) score (SMD =-0.84, 95% CI: -1.24 to -0.45, P< 0.0001), the Oswestry Disability Index (ODI) score (SMD =-0.74, 95% CI: -0.95 to -0.54, P< 0.00001), Forced Vital Capacity (FVC) score (MD = 0.24, 95% CI: 0.10 to 0.37, P= 0.0006), Forced Expiratory Volume in 1 second /Forced Vital Capacity (FEV1/FVC) (MD = 1.90, 95% CI: 0.73 to 3.07, P= 0.001), although there was no significant difference between the breathing exercises and control interventions for Forced Expiratory Volume in the first second (FEV1) score (MD = 0.22, 95% CI = [0.00, 0.43], P= 0.05), and Maximal Voluntary Ventilation (MVV) score (MD = 8.22, 95% CI = [-4.02, 20.45], P= 0.19).

CONCLUSION

Breathing exercises can reduce pain, assist people with lumbar disabilities, and improve pulmonary function, and could be considered as a potential alternative treatment for CLBP.

Effect of Adding Diaphragmatic Breathing Exercises to Core Stabilization Exercises on Pain, Muscle Activity, Disability, and Sleep Quality in Patients With Chronic Low Back Pain: A Randomized Control Trial

Objective

The purpose of this study was to test the effect of adding diaphragmatic breathing exercises (DBEs) to core stabilization exercises (CSEs) for patients with chronic low back pain (CLPB).

Methods

Twenty-two patients with CLPB were randomly allocated to the experimental (DBE + CSE) or control group (CSE only). They were given 12 treatment sessions 3 times a week for 4 weeks. Patients were evaluated before and after the 12 sessions. Surface electromyography of transverse abdominis, Oswestry Disability Index, Fear Avoidance Belief Questionnaire, Pittsburgh Sleep Quality Index, Numeric Pain Rating Scale, and chest expansion were used as outcome measures for pain, muscle activity, disability, and sleep quality.

Results

The outcome measure scores showed statistical significance of (P = .01) in time effect on muscle activity, sleep quality, disability score, pain score, fear-avoidance belief of patients and chest expansion; and group effect on Fear Avoidance Belief Questionnaire and physical activity parameter (P = .05). An interaction effect (time x group) on muscle activity for right transverse abdominus during tuck in (P = .01) and chest expansion (P = .01) was also found; however, no significant difference was found related to other parameters.

Conclusion

The combination of DBE and CSE interventions compared to CSE alone showed improvement in the measured parameters for patients with CLBP. Incorporating DBE with CSE also improved muscle activation and chest expansion.

Biological Responses to Local Vibratory Stimulation for the Lower Legs and Lower Back and Criterion Values Based on Sweep Frequencies of Healthy Individuals: An Observational Study

Declining proprioceptive function is associated with problems such as lower back pain and falls. Therefore, we developed a vibration device using sweep frequency to evaluate several proprioceptors with different response frequency ranges. This study aimed to elucidate the biological responses of healthy individuals to vibratory stimulation at different sites and frequency ranges and to propose cutoff values to determine the decline in proprioceptive function. Mechanical vibration was separately applied to the lower legs and lower back, and proprioceptive function was evaluated by defining the ratio of the center of pressure (CoP) in the anteroposterior direction during mechanical vibration to that during no vibration in the three frequency ranges. The cut-off value was defined as the mean value, with the standard deviation subtracted for each indicator. The cut-off values were higher in the lower legs than in the lower back at all frequency ranges and in the 30-53 Hz and 56-100 Hz frequency ranges for both the lower legs and lower back. In healthy individuals, 9.9% and 8.6% were below the cut-off values in the 30-53 Hz and 56-100 Hz frequency ranges for the lower legs, respectively.

Role of the Inspiratory Muscles on Functional Performance From Critical Care to Hospital Discharge and Beyond in Patients With COVID-19

OBJECTIVE

The role of inspiratory muscle performance in functional performance in patients with coronavirus disease 2019 (COVID-19) is poorly understood. The purpose of this study was to perform a longitudinal examination of inspiratory and functional performance from intensive care unit (ICU) discharge (ICUD) to hospital discharge (HD) and symptoms at HD and 1 month after HD in patients with COVID-19.

METHODS

Thirty patients (19 men, 11 women) with COVID-19 were included. Examination of inspiratory muscle performance at ICUD and HD was performed with an electronic manometer, which provided the maximal inspiratory pressure (MIP) and several other inspiratory measures. Examination of dyspnea and functional performance was performed at ICUD and HD with the Modified Borg Dyspnea Scale and the 1-minute sit-to-stand test (1MSST), respectively.

RESULTS

The mean age was 71 (SD = 11) years, the mean length of ICU stay was 9 (SD = 6) days, and the mean length of hospital stay was 26 (SD = 16) days. Most of the patients were diagnosed with severe COVID-19 (76.7%) and had a mean Charlson Comorbidity Index of 4.4 (SD = 1.9), reflecting high comorbidity. The mean MIP of the entire cohort increased minimally from ICUD to HD (from 36 [SD = 21] to 40 [SD = 20] cm H2O), reflecting predicted values for men and women at ICUD and HD of 46 (25%) to 51 (23%) and 37 (24%) to 37 (20%), respectively. The 1MSTS score increased significantly from ICUD to HD (9.9 [SD = 7.1] vs 17.7 [SD = 11.1]) for the entire cohort but remained far below population-based reference values (2.5th percentile) for the majority of patients at ICUD and HD. At ICUD, MIP was found to be a significant predictor of a favorable change in 1MSTS performance (β = 0.308; odds ratio = 1.36) at HD.

CONCLUSION

A significant reduction in inspiratory and functional performance exists in patients with COVID-19 at both ICUD and HD, with a greater MIP at ICUD being a significant predictor of a greater 1MSTS score at HD.

IMPACT

This study shows that inspiratory muscle training may be an important adjunct after COVID-19.

Impact of Indoor Air Quality and Breathing on Back and Neck Pain: A Systematic Review

Back pain and neck pain are important public health concerns and are among the most common and disabling conditions globally. However, the relationships among indoor air quality (IAQ), breathing parameters (pulmonary function, respiratory disorders), and back pain and neck pain have not been adequately assessed. The purpose of this study was to systematically review the literature about the impact of IAQ and breathing parameters on back pain and neck pain (PROSPERO ID: CRD42022380515). CINAHL, EMBASE, PEDRo, and PubMed databases were searched through January 19, 2023. Inclusion criteria for study eligibility were observational studies (except case reports) or randomized controlled trials (RCTs), published in peer-reviewed journals in the English language, human research, original research, examined the relationships between IAQ, or breathing parameters with back pain or neck pain. Review procedures were conducted and reported according to PRISMA recommendations. Empirical evidence statements were developed for observational studies, and grades of evidence statements were developed for RCTs. Sixty-seven eligible studies were found (54 observational studies and 13 RCTs) that enrolled 345,832 participants. None of the studies assessed the combined impact of IAQ and breathing parameters on back pain or neck pain. No level 1 studies were found, which precludes making strong statements about causality and strong recommendations about the efficacy of IAQ and breathing exercise interventions for reducing pain and disability related to back pain and neck pain. Evidence indicates that poor IAQ and respiratory disorders are related to an increased risk of back pain and neck pain. Conflicting evidence exists about the association between pulmonary function with back pain and neck pain. Evidence for breathing exercise interventions was mixed with numerous limitations. This review provides preliminary evidence on the relationships of IAQ and breathing parameters with back pain and neck pain, which can be used to guide future research and clinical implementation efforts. Assuming positive findings in subsequent research, a wide range of stakeholders involved with this complex human-building-environment interface can be equipped to address IAQ and breathing parameters, along with other established risk factors to help those suffering from back pain and neck pain.

Adherence and Effect of Home-Based Rehabilitation with Telemonitoring Support in Patients with Chronic Non-Specific Low Back Pain: A Pilot Study

Home-based exercises have been on the rise recently. This pilot study aimed to assess the adherence and effect of a home-based rehabilitation programme using telemonitoring in patients with chronic non-specific low back pain (CNLBP). Twenty-seven patients with CNLBP were enrolled in the study, each of whom underwent a neurological assessment, including patient-oriented measures and a functional assessment-a battery of tests that comprehensively evaluated trunk muscle function. The rehabilitation programme lasted 18 weeks and included daily home-based exercises. A mobile application or an exercise diary was used to monitor compliance. Adherence to the programme was excellent for both the diary and mobile application groups, with 82.3% in the diary group exercising at least once a day and 72.9% twice a day, and 94.8% in the mobile application group exercising at least once a day and 86.6% twice a day. Both patient-oriented and functional outcomes improved significantly; however, the relative changes of the parameters in these two groups did not correlate, which supports the idea that trunk muscle function does not directly relate to patient complaints and that CNLBP is a multifactorial issue. This model of rehabilitation programme should be used in clinical practice, as its adherence and effectiveness seem noticeable.

Exploring the role of respiratory intervention as an effective adjunct tool in the management of chronic low back pain: A scoping systematic review

BACKGROUND

Individuals with chronic low back pain (CLBP) are usually prescribed manual therapy and exercise programs. Respiratory exercise interventions are also recommended by some researchers for CLBP. However, the evidence for the relative effectiveness of these treatments is limited, and the question of which sort of intervention is most suited remains unanswered.

OBJECTIVE

This systematic review aims to evaluate the effectiveness of respiratory interventions in CLBP.

METHODS

A systematic search was performed using databases: PubMed, Web of Science, PEDro, Cochrane Library, and Science Direct. The review was registered in PROSPERO (CRD42021233739).

RESULTS

Seven studies met the inclusion criteria. Out of these, one was of poor, three were of fair, and three were of good qualities. A total of 293 subjects were included in seven studies, the mean age of subjects ranged from 21 to 53 years. The largest effect size was reported for pain (d = 1.5) and maximum inspiratory pressure (d = 1.38). No detrimental effects were reported for any of the intervention programs.

CONCLUSIONS

Since most of the research has been done on pain and MIP, and both of these parameters have revealed significant changes with large effect size, therefore it can be concluded that respiratory interventions improve pain and MIP in CLBP. Owing to the limited number of studies available, a definitive outcome could not be documented for other parameters. Thus, further research is needed to provide a more robust piece of evidence and understanding.

Adherence to and impact of home-based high-intensity IMT in people with spinal cord injury: a pilot study

Study design

The pilot study was completed in 5 phases (Control and 4 phases of IMT) incorporating assessments at Baseline 1 (BL1), BL2, Follow-up 1 (F1), F2, F3, and F4.

Objective

To assess the adherence and impact of a daily high-intensity (80% of max) inspiratory muscle training (IMT) home program with once weekly supervision for people with spinal cord injury (SCI).

Setting

Assessments: research institution or zoom. IMT: participant’s home.

Methods

Participants completed daily IMT in IMT Phase 1 and 2, once weekly in IMT Phase 3, self-selected frequency in IMT Phase 4. All phases had one weekly supervised session except IMT Phase 4. Primary outcomes included adherence and a difficulty score [DS (0- not difficult to 10- the most difficult)]. Secondary outcomes included respiratory function and seated balance.

Results

Data from 10 people with chronic SCI (>1 year) (Cervical level of injury: 6, AIS: A-B, injury duration: 10.9 years 95% CI [3.9, 18.1]) were used in the analysis. Participants completed 69% of their training days in IMT Phase 1 and 65% overall reporting an average DS of 7.4 ± 1.4. Only one participant completed training during IMT Phase 4. One participant’s training load was reduced due to suspected overtraining. Maximal inspiratory pressure (MIP), sustained MIP (SMIP), and total power (TP), improved significantly (p < 0.05) from BL2 to F1.

Conclusion

Our data suggest that people with SCI can perform high-intensity IMT at home to improve inspiratory performance. It is strongly recommended that participants be intermittently monitored for adherence and safety.

ClinicalTrials.gov Registration number: NCT04210063.

Respiratory muscle endurance training improves exercise performance but does not affect resting blood pressure and sleep in healthy active elderly

Purpose

Ageing is associated with increased blood pressure (BP), reduced sleep, decreased pulmonary function and exercise capacity. The main purpose of this study was to test whether respiratory muscle endurance training (RMET) improves these parameters.

Methods

Twenty-four active normotensive and prehypertensive participants (age: 65.8 years) were randomized and balanced to receive either RMET (N = 12) or placebo (PLA, N = 12). RMET consisted of 30 min of volitional normocapnic hyperpnea at 60% of maximal voluntary ventilation while PLA consisted of 1 inhalation day⁻¹ of a lactose powder. Both interventions were performed on 4–5 days week⁻¹ for 4–5 weeks. Before and after the intervention, resting BP, pulmonary function, time to exhaustion in an incremental respiratory muscle test (incRMET), an incremental treadmill test (IT) and in a constant-load treadmill test (CLT) at 80% of peak oxygen consumption, balance, sleep at home, and body composition were assessed. Data was analyzed with 2 × 2 mixed ANOVAs.

Results

Compared to PLA, there was no change in resting BP (independent of initial resting BP), pulmonary function, IT performance, sleep, body composition or balance (all p > 0.05). Performance significantly increased in the incRMET (+ 6.3 min) and the CLT (+ 3.2 min), resulting in significant interaction effects (p < 0.05).

Conclusion

In the elderly population, RMET might be used to improve respiratory and whole body endurance performance either as an adjunct to physical exercise training or as a replacement thereof for people not being able to intensively exercise even if no change in BP or sleep may be expected.

Influence of Speech and Cognitive Load on Balance and Timed Up and Go

The interaction between oral and/or mental cognitive tasks and postural control and mobility remains unclear. The aim of this study was to analyse the influence of speech production and cognitive load levels on static balance and timed up and go (TUG) during dual-task activities. Thirty healthy young subjects (25 ± 4 years old, 17 women) participated in this study. A control situation and two different cognitive arithmetic tasks were tested: counting backward in increments of 3 and 7 under oral (O) and mental (M) conditions during static balance and the TUG. We evaluated the dual-task cost (DTC) and the effect of speech production (SP) and the level of cognitive load (CL) on these variables. There was a significant increase in the centre of pressure oscillation velocity in static balance when the dual task was performed orally compared to the control situation The DTC was more pronounced for the O than for the M. The SP, but not the CL, had a significant effect on oscillation velocity. There was an increase in TUG associated with the cognitive load, but the mental or oral aspect did not seem to have an influence. Mobility is more affected by SP when the cognitive task is complex. This may be particularly important for the choice of the test and understanding postural control disorders.

Inspiratory Muscle Performance Is Related to Seated Balance Function in People With Spinal Cord Injury: An Observational Study

OBJECTIVE

To examine the relationship between inspiratory muscle performance (IMP) and functional sitting balance (FSB) in persons with chronic spinal cord injury (SCI). We hypothesized that a moderate correlation would be found between IMP and FSB and that individuals with better balance would have better IMP.

DESIGN

The SCI-specific modification of the Function in Sitting Test (FIST-SCI) measured FSB. The IMP measures included (1) maximal inspiratory pressure (MIP), (2) sustained MIP (SMIP), and (3) inspiratory duration. Upper extremity motor score (UEMS) and level of injury (LOI) were taken from International Standards for Neurological Classification of Spinal Cord Injury examinations. Spearman correlational analyses assessed relationships among these factors in the sample (N=37). Mann-Whitney U tests explored differences between 2 comparison group pairs (tetraplegia group [TG] vs paraplegia group [PG]; independent transfer group [ITG] vs assisted transfer group [ATG]). Regression analysis examined variables predictive of FSB in the TG.

SETTING

Research facility.

PARTICIPANTS

Volunteers with tetraplegia (n=21, American Spinal Injury Association Impairment Scale (AIS) A=8, B=7, C=6) and paraplegia (n=16, AIS A=9, B=4, C=3) (N=37).

INTERVENTION

Not applicable.

MAIN OUTCOME MEASURES

IMP, LOI, UEMS, FIST-SCI.

RESULTS

UEMS, MIP, SMIP, and LOI had moderate to high correlations with FIST-SCI scores (ρ=0.720 (P<.001), 0.480 (P=.003), 0.467 (P=.004), 0.527 (P=.001), respectively). UEMS, MIP, and FIST-SCI scores were higher in the PG and ITG than the TG and ATG, respectively (PG vs. TG P values=<.001, .008, .002, respectively, and ITG vs. ATG P values=<.001, .032, <.001, respectively). Further, SMIP and UEMS predicted FIST-SCI balance scores in the TG, accounting for 55% of total variance (P<.001) (FIST-SCI=11.88+0.03 [SMIP]+0.425 [UEMS]).

CONCLUSIONS

The relationship between IMP and balance appears preserved after SCI. FSB was predicted, in part, via UEMS and SMIP in the TG. Future research should focus on the effect of SCI-based breathing interventions on FSB.

Pulmonary and Inspiratory Muscle Function Response to a Mountain Ultramarathon

The study aimed to provide within-race data on the time course of pulmonary function during a mountain ultramarathon (MUM). Additionally, we wanted to assess possible sex differences regarding pre- to post-race change in pulmonary and inspiratory muscle function. Lastly, we were interested in evaluating whether changes in respiratory function were associated with relative running speed and due to general or specific fatigue. 47 athletes (29 males and 18 females; 41 ± 5 years) were submitted to a cardiopulmonary exercise test (CPET) before a 107-km MUM. Spirometric variables: forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), FEV₁/FVC and peak expiratory flow (PEF); maximal inspiratory pressure (MIP); squat jump (SJ) and handgrip strength (HG) were assessed before and after the race. Additionally PEF was measured at three aid stations (33^rd, 66^th and 84^th km) during the race. PEF declined from the 33^rd to the 66^th km (p = 0.004; d = 0.72) and from the 84^th km to the finish line (p = 0.003; d = 0.90), while relative running speed dropped from the first (0-33 km) to the second (33-66 km) race section (p < 0.001; d = 1.81) and from the third (66-84 km) to the last race section (p < 0.001; d = 1.61). Post-race, a moderate reduction was noted in FVC (-13%; p < 0.001; d = 0.52), FEV₁ (-19.5%; p < 0.001; d = 0.65), FEV₁/FVC (-8.4%; p = 0.030; d = 0.59), PEF (-20.3%; p < 0.001; d = 0.58), MIP (-25.3%; p < 0.001; d = 0.79) and SJ (-31.6%; p < 0.001; d = 1.42). Conversely, HG did not change from pre- to post-race (-1.4%; p = 0.56; d = 0.05). PEF declined during the race in parallel with running speed drop. No sex differences were noted regarding post-race respiratory function, except that FEV₁/FVC decay was significantly greater among women. The magnitude of pre- to post-race respiratory function decline was uncorrelated with relative running speed.

Assessment of Lumbar Extensor Muscles in the Context of Trunk Function, a Pilot Study in Healthy Individuals

A comprehensive assessment of trunk function, including the lumbar extensor muscles, appears to be important in various conditions affecting axial musculature. This pilot cross-sectional observational study aimed to define a battery of tests that comprehensively assess trunk muscle function (strength and muscular endurance). Sixty subjects without low back pain (LBP) underwent measurement of isometric lower back extensor strength using a hand-held dynamometer (HHD) in three positions; measurement of respiratory muscle strength; and Biering-Sørensen, prone-plank, and side-bridge tests. The repeatability, short-term and long-term reliability using the HHD device in different postural positions was confirmed. The greatest isometric lower back extensor strength was generated in the sitting position by male subjects. Time of effort in the Biering-Sørensen test was longer in women and older subgroups than in men and younger individuals, although this was not the case for the other two muscular endurance tests. This pilot monitoring of trunk muscle strength and endurance in healthy volunteers may lead to a better understanding of trunk muscle function. Based on this methodological background, the authors aim to use the defined battery of tests in their further studies in a group of patients with LBP and certain neuromuscular diseases to verify its usefulness in clinical practice.

The Effect of Fatigue on Single-Leg Postural Sway and Its Transient Characteristics in Healthy Young Adults

Neuromuscular fatigue is known to impair balance ability, which is reflected in increased postural sway during quiet standing tasks. Recently, quantifying transient characteristics of postural sway has been suggested as an approach to obtain additional information regarding postural control. However, this approach is currently vastly unexplored. The purpose of this study was to investigate the effects of fatigue (induced by a repeated change of direction task) on postural sway and its transient characteristics during single-leg standing, including whole-trial estimates and indexes of transient behavior in young healthy active adults. The study involved 28 physically active students (14 females). Single-leg postural sway was recorded for 30s before and after a fatiguing protocol, which consisted of a repeated change of direction tasks. We calculated the traditional whole-trial estimates of postural sway [center-of-pressure (CoP) velocity and amplitude in anterior-posterior (AP) and medial-lateral (ML) directions] and corresponding transient behavior indexes, based on three 10-s intervals. Statistically significant sex×fatigue interaction with medium effect sizes was found for whole-trial CoP velocity in AP (p=0.028; η²=0.17) and ML directions (p=0.019; η²=0.19). Post-hoc test showed that both variables substantially decreased in female participants (p=0.041–0.045; d=0.54–0.56), but remained similar in males (p=0.194–0.294). There were small to medium statistically significant main effects of fatigue on transient index for CoP amplitude in both directions (p=0.042–0.049; η²=0.02–0.14). Notably, CoP AP amplitude increased in the first 10-s interval for males (before fatigue: 5.6±1.3mm; after fatigue: 6.3±1.6mm), while the CoP AP amplitude in the third interval remained similar after fatigue (before fatigue: 5.5±1.4mm; after fatigue: 5.1±1.2mm). In conclusion, the responses to fatigue in terms of postural sway were time interval specific, and there were certain sex-differences in responses to fatigue, which could be related to better ability to adapt balance strategies in females. Moreover, our results demonstrate that the indexes of transient behavior could perhaps detect smaller fatigue-induced changes in postural sway that are seen in whole-trial estimates.

Body Balance and Physiotherapy in the Aquatic Environment and at a Gym

The increase in the average age of our society represents a growing medical and social problem, which requires concentration on the issue concerning balance disorders. The aquatic environment has a number of complex properties that have miscellaneous effects on the human body. In the light of the above, water is becoming an ideal environment to learn correct neuromuscular communication, and a properly prepared training session in water helps to practice balance and movement coordination. The objective of the study was to assess the impact of rehabilitation in the aquatic environment on patients' balance and compare the results obtained with patients who received rehabilitation at a gym. The study was carried out among patients hospitalised in the “Krzeszowice” Rehabilitation Centre. It encompassed 137 patients, randomly assigned to either the study group (the aquatic environment) or the control group (the gym). The preliminary examination included general medical history and a test on the stabilometric platform. The patients attended training sessions for 4 weeks, 5 times a week for 30 minutes. It was a single-blinded study wherein the authors did not know which group a given patient had been assigned to. Upon completion of a monthly therapy, the stabilometric test was carried out again. The study revealed that the patients from both groups experienced a significant improvement in balance. However, the improvement was slightly greater in those exercising in the pool. Physiotherapy in the aquatic environment makes a greater contribution to the improvement of body balance compared to physical exercises performed at a gym.

Diaphragm thickness, thickness change, and excursion in subjects with and without nonspecific low back pain using B-mode and M-mode ultrasonography

Background: Previous studies have demonstrated that respiratory dysfunction has a potential association with low back pain (LBP). Despite the role of the diaphragm for respiration and spinal stability, knowledge of the function of both sides of the diaphragm in subjects with LBP is still limited.Objective: This study aimed to compare the structural integrity and function of the right and left hemidiaphragm by ultrasonography (USG) in subjects with and without nonspecific chronic low back pain (NS-CLBP).Methods: A total of 37 subjects with NS-CLBP and 34 healthy subjects participated in this case-control study. The thickness, thickness change, and excursion of the right and left hemidiaphragm were compared within and between the groups during quiet breathing (QB) and deep breathing (DB) through B-mode and M-mode ultrasound imaging.Results: The LBP group had a significantly smaller degree of right hemidiaphragm thickness change (P = .001) compared with the healthy control group, with a strong effect size. Nevertheless, there was no significant change for diaphragm thickness and excursion between the two groups. The result showed that, in the healthy group, the right hemidiaphragm had a significantly smaller thickness at expiration and larger thickness change compared with the left hemidiaphragm, with a moderate effect size. Based on the multivariate prediction analysis, the right hemidiaphragm thickness change might significantly predict LBP.Conclusion: We found that participants with LBP had a smaller degree of right hemidiaphragm thickness change. Also, the right hemidiaphragm thickness change might significantly predict LBP.

Effects of Manual Therapy on the Diaphragm in the Musculoskeletal System: A Systematic Review

OBJECTIVES

To analyze the effects at the musculoskeletal level of manual treatment of the diaphragm muscle in adults.

DATA SOURCES

Systematic review using 4 databases: PubMed, Science Direct, Web of Science, and Scopus.

STUDY SELECTION AND DATA EXTRACTION

Two independent reviewers applied the selection criteria and assessed the quality of the studies using the Physiotherapy Evidence Database scale for experimental studies. A third reviewer intervened in cases where a consensus had not been reached. A total of 9 studies were included in the review.

DATA SYNTHESIS

Manual therapy directed to the diaphragm has been shown to be effective in terms of the immediate increase in diaphragmatic mobility and thoracoabdominal expansion. The immediate improvement in the posterior muscle chain flexibility test is another of the most frequently found findings in the evaluated studies. Limited studies show improvements at the lumbar and cervical level in the range of motion and in pain.

CONCLUSION

Manual diaphragm therapy has shown an immediate significant effect on parameters related to costal, spinal, and posterior muscle chain mobility. Further studies are needed, not only to demonstrate the effectiveness of manual diaphragm therapy in the long-term and in symptomatic populations, but also to investigate the specific neurophysiological mechanisms involved in this type of therapy.

The influence of cognitive load on static balance in chronic obstructive pulmonary disease patients

INTRODUCTION

Patients with chronic obstructive pulmonary disease (COPD) may demonstrate cognitive function and balance deterioration. These two phenomena are often realized simultaneously during daily living activities, where the risk of falling may be increased due to possible postural disturbance when focusing on a cognitive task during motion. Despite the high rate of falls in COPD, there is currently a lack of affordable clinical instruments to quantify the interaction between cognitive tasks and static balance in these patients. Therefore, this study aims to assess the balance perturbation induced by cognitive tasks using a new cost-effective protocol which can easily be implemented in clinical settings.

METHOD

A total of 21 COPD patients (Age: 64 ± 8 yrs, Forced Expiratory Volume in one second = 41 ± 17%, Women: 7) and 21 matched healthy controls participated in the study. They performed two cognitive tasks (counting backward by 3s and naming animals) with eyes open and with eyes closed. Each trial lasted 60 s, with balance-related parameters recorded and quantified using a Wii Balance Board. A three-way ANOVA (cognitive task, eyes action, and health status) for balance-related parameters derived from the center of pressure displacement was performed.

RESULTS

COPD, vision, and cognitive tasks altered the balance; no interaction between conditions was observed. There was no correlation between cognitive ability, respiratory function, and the balance-related parameters.

CONCLUSION

Compared to healthy controls, the COPD patients had impaired balance. Cognitive tasks altered postural control in both COPD and controls, where this alteration was more pronounced with eyes closed.

Inspiratory and Lower-Limb Strength Importance in Mountain Ultramarathon Running. Sex Differences and Relationship with Performance

The study was aimed at comparing lower-limb strength and respiratory parameters between male and female athletes and their interaction with performance in a 107 km mountain ultramarathon. Forty seven runners (29 males and 18 females; mean ± SD age: 41 ± 5 years) were enrolled. Lower-limb strength assessment comprised a squat jump test, an ankle rebound test, and an isometric strength test. Respiratory assessment included pulmonary function testing and the measurement of maximal inspiratory pressure. Male athletes performed largely better in the squat jump (26 ± 4 vs. 21 ± 3 cm; p < 0.001; d = 1.48), while no sex differences were found in the other two lower-limb tests. Concerning the respiratory parameters, male athletes showed largely greater values in pulmonary expiratory variables: forced vital capacity (5.19 ± 0.68 vs. 3.65 ± 0.52 L; p < 0.001; d = 2.53), forced expiratory volume in 1 s (4.24 ± 0.54 vs. 2.97 ± 0.39 L; p < 0.001; d = 2.69), peak expiratory flow (9.9 ± 1.56 vs. 5.89 ± 1.39 L/min; p < 0.001; d = 2.77) and maximum voluntary ventilation in 12 s (171 ± 39 vs. 108 ± 23 L/min; p < 0.001; d = 1.93); while no sex differences were identified in maximal inspiratory pressure. Race time was associated with ankle rebound test performance (r = −0.390; p = 0.027), isometric strength test performance (r = −0.349; p = 0.049) and maximal inspiratory pressure (r = −0.544; p < 0.001). Consequently, it seems that athletes competing in mountain ultramarathons may benefit from improving lower-limb isometric strength, ankle reactive strength and inspiratory muscle strength. Nevertheless, further interventional studies are required to confirm these exploratory results. In addition, the fact that the magnitude of the sex difference for isometric strength was minor, as compared with the other strength tests, could represent one of the factors explaining why the performance gap between males and females is reduced in ultramarathons.

Postural Sway during Local Vibratory Stimulation for Proprioception in Elderly Individuals with Pre-Sarcopenia

OBJECTIVE

Many studies have demonstrated that the loss of muscle mass (LMM) poses a risk of postural instability in the elderly; however, few studies have shown how LMM decreases proprioception. In this study, we investigated the changes in postural sway among older individuals with LMM induced by application of a local vibratory stimulus.

METHOD

We enrolled 64 older adults (mean age). Postural sway was measured while applying vibration stimuli of 30, 60, and 240 Hz to both the gastrocnemius and lumbar multifidus muscles. We also measured the relative proprioceptive weighting ratio (RPW) of postural sway. The patients were divided into LMM and non-LMM (NLMM) groups. The study subjects were compared in terms of their age, height, weight, body mass index (BMI), lower leg skeletal muscle mass index (LSMI), L4/5 lumbar multifidus cross-sectional area ratio, and RPW at 30, 60, and 240 Hz.

RESULTS

Subjects in the LMM group showed a significantly lower RPW at 60 Hz, LSMI, and BMI than did those in the NLMM group.

CONCLUSIONS

Decrease in RPW with 60-Hz stimulation concerning the lower leg proprioception is a risk factor for LMM-associated postural instability in the elderly. Consequently, with respect to the gastrocnemius muscles proprioception in LMM, it is necessary to perform assessments using muscle spindle stimuli.

Influence of phase of respiratory cycle on ultrasound imaging of deep abdominal muscle thickness

BACKGROUND

It is difficult to evaluate the transversus abdominis (TrA) and internal oblique (IO) due to their dual role in both trunk control and breathing.

OBJECTIVES

To investigate whether TrA and IO thickness as measured by ultrasound differs across the respiratory cycle in upright standing.

DESIGN

Observational study.

METHODS

Thickness of TrA and IO was measured with ultrasound in 67 subjects in upright standing. Measures were performed 3 times and by 2 assessors, at the end of relaxed expiration, at the end of a full inspiration, and at the end of full expiration. Differences were assessed by ANOVA. Intra- and inter-rater reliability (of a single measure and the average of 3 measures) were assessed by intra-class correlation (ICC).

RESULTS

Thickness of the TrA and IO was higher at full expiration than at the end of relaxed expiration (p < 0.001), and in turn compared to at full inspiration (p < 0.001). Intra-rater reliability was excellent at all respiratory phases (ICC 0.76-0.87). Whereas inter-rater reliability for a single measure was only fair to good for TrA (ICC 0.52-0.71) and good to excellent for IO (ICC 0.61-0.78), the inter-rater reliability of the average was excellent at all respiratory phases (ICC 0.75-0.90).

CONCLUSIONS

Thickness of TrA and IO increases when lung volume decreases. The intra- and inter-rater reliability of an average measure were excellent at the end of relaxed expiration, full inspiration and full expiration. This provides new opportunities to evaluate the deep abdominal muscles, and their role in respiration, in a physiotherapeutic setting.

Association Between Back Muscle Strength and Proprioception or Mechanoreceptor Control Strategy in Postural Balance in Elderly Adults with Lumbar Spondylosis

This study aimed to investigate the relationship between back muscle strength and proprioception or mechanoreceptor control strategies used for postural balance in elderly adults with lumbar spondylosis. The displacement of the center of pressure (COP) excursion was determined in 24 elderly adults with lumbar spondylosis and 24 healthy young adults while the participants were standing upright on a balance board with their eyes closed. Vibratory stimulations of 30, 60, and 240 Hz were applied to the gastrocnemius (GS) and lumbar multifidus (LM) muscles to evaluate the effect of different proprioceptive signals on postural control. Back muscle strength was evaluated. Spearman’s rank correlation analysis was performed to determine the relationship between back muscle strength and significant COP excursion. Compared with young adults, elderly adults with lumbar spondylosis showed an increase in COP excursion displacement when a vibratory stimulation of 240 Hz was applied to the GS (P = 0.002) and LM muscles (P < 0.001). LM stimulation at 240 Hz was significantly associated with back muscle strength (P = 0.038). Postural control assessment with 240-Hz mechanoreceptor stimulation of the trunk could be a good indicator of postural instability due to over-dependence on mechanoreceptors and back muscle weakness in elderly adults with lumbar spondylosis.

The rapid recovery of vertical force propulsion production and postural sway after a specific fatigue protocol in female handball athletes

BACKGROUND

Muscle fatigue is characterized by a decrease in muscle performance, accompanied by an increase in perceived exertion to produce a desired amount of force. The duration of the fatigue effects is not completely clear regarding postural sway and force production in athletes.

RESEARCH QUESTION

What is the effect of a specific fatigue protocol in postural sway and force production in female handball athletes and the recovery time necessary for these variables?

METHODS

Twenty female handball athletes participated in this study. Specific handball actions composed the fatigue protocol in the format of a circuit with the gradual increment of laps. They stood upright in one-leg posture on a force plate. For the maximum propulsion force (FMAX), they performed a countermovement jump on the force plate. The center of pressure (COP) and the FMAX were obtained at baseline, immediately after the exhaustion due to the fatigue protocol and every minute during the first 10 min of the recovery phase.

RESULTS

The FMAX decreased ∼9.5% after the fatigue protocol, whereas de COP area increased 224%. During the recovery phase, the FMAX and the COP area returned to baseline values after five minutes.

SIGNIFICANCE

The first five minutes immediately after the fatigue protocol represent the time interval where the fatigue effects are still present. Future studies willing to investigate the effects of fatigue in athletes should perform the analysis within this short time-window.

Functional training of the inspiratory muscles improves load carriage performance

Inspiratory Muscle Training (IMT) whilst adopting body positions that mimic exercise (functional IMT; IMT_F) improves running performance above traditional IMT methods in unloaded exercise. We investigated the effect of IMT_F during load carriage tasks. Seventeen males completed 60 min walking at 6.5 km·h^-1 followed by a 2.4 km load carriage time-trial (LC_TT) whilst wearing a 25 kg backpack. Trials were completed at baseline; post 4 weeks IMT (consisting of 30 breaths twice daily at 50% of maximum inspiratory pressure) and again following either 4 weeks IMT_F (comprising four inspiratory loaded core exercises) or maintenance IMT (IMT_CON). Baseline LC_TT was 15.93 ± 2.30 min and was reduced to 14.73 ± 2.40 min (mean reduction 1.19 ± 0.83 min, p < 0.01) after IMT. Following phase two, LC_TT increased in IMT_F only (13.59 ± 2.33 min, p < 0.05) and was unchanged in post-IMT_CON. Performance was increased following IMT_F, providing an additional ergogenic effect beyond IMT alone. Practitioner Summary: We confirmed the ergogenic benefit of Inspiratory Muscle Training (IMT) upon load carriage performance. Furthermore, we demonstrate that functional IMT methods provide a greater performance benefit during exercise with thoracic loads. Abbreviations: [Lac^-]_B: blood lactate; FEV₁: forced expiratory volume in one second; FEV₁/FVC: forced expiratory volume in one second/forced vital capacity ratio; FVC: forced vital capacity; HR: heart rate; IMT: inspiratory muscle training; IMT_CON: inspiratory muscle training maintenance; IMT_F: functional inspiratory muscle training; LC: load carriage; LC_TT: load carriage time trial; P_di: transdiaphragmatic pressure; PEF: peak expiratory flow; P_Emax: maximum expiratory mouth pressure; P_Imax: maximum inspiratory mouth pressure; RPE: rating of perceived exertion; RPE_breating: rating of perceived exertion for the breathing; RPE_leg: rating of perceived exertion for the legs; SEPT: sport-specific endurance plank test; V̇ O₂: oxygen consumption; V̇ O_2peak: peak oxygen consumption.

The effect of a passive trunk exoskeleton on metabolic costs during lifting and walking

The objective of this study was to assess how wearing a passive trunk exoskeleton affects metabolic costs, movement strategy and muscle activation during repetitive lifting and walking. We measured energy expenditure, kinematics and muscle activity in 11 healthy men during 5 min of repetitive lifting and 5 min of walking with and without exoskeleton. Wearing the exoskeleton during lifting, metabolic costs decreased as much as 17%. In conjunction, participants tended to move through a smaller range of motion, reducing mechanical work generation. Walking with the exoskeleton, metabolic costs increased up to 17%. Participants walked somewhat slower with shortened steps while abdominal muscle activity slightly increased when wearing the exoskeleton. Wearing an exoskeleton during lifting decreased metabolic costs and hence may reduce the development of fatigue and low back pain risk. During walking metabolic costs increased, stressing the need for a device that allows disengagement of support depending on activities performed. Practitioner summary: Physiological strain is an important risk factor for low back pain. We observed that an exoskeleton reduced metabolic costs during lifting, but had an opposite effect while walking. Therefore, exoskeletons may be of benefit for lifting by decreasing physiological strain but should allow disengagement of support when switching between tasks. Abbreviations: COM: centre of mass; EMG: electromyography; LBP: low back pain; MVC: maximum voluntary isometric contraction; NIOSH: National Institute for Occupational Safety and Health; PLAD: personal lift augmentation device; PWS: preferred walking speed without exoskeleton; PWSX: preferred walking speed with exoskeleton; ROM: range of motion; RER: respiratory exchange ratio; V ̇O2max: maximum rate of oxygen consumption.

Effects of Plantar Flexor Muscles Fatigue on Postural Control during Quiet Stance and External Perturbation in Healthy Subjects

BACKGROUND

The maintenance of postural control is a key component in dynamic physical activity, especially during muscle fatigue and against external forces. Despite many studies in this field, there is no consensus regarding the effects of plantar flexor muscles fatigue on postural control during different postural tasks.

OBJECTIVE

To evaluate the effects of plantar flexor muscles fatigue on postural control during quiet stance and external perturbation in healthy subjects.

MATERIAL AND METHODS

Twenty four healthy individuals (20-35 years) participated this interventional study. The foot center of pressure data was measured using a single force platform, and then the postural control parameters, including the center of pressure displacement and velocity in the anterior-posterior and medial-lateral direction and also path length calculated under two conditions; quiet and perturbed stance, before and after plantar flexor muscles fatigue.

RESULTS

The statistical analysis demonstrated that mean displacement and velocity of the center of pressure in the anterior-posterior direction and also path length increased after the fatigue protocol in the perturbed condition. However, fatigue had no significant effects on postural control parameters in the quiet standing condition.

CONCLUSION

These results indicated that the effects of muscle fatigue on postural control depend on the difficulty of the task and the relevance of proprioceptive information. The postural control system appears to use distinct control strategies in different situations such as quiet and perturbed stance conditions, and these strategies may be differentially altered by fatigue. In conclusion, due to the potential risk of loss of balance, it is important to take the role of plantar flexor muscle fatigue into account during more difficult postural tasks.

Validation of the Wii Balance Board to assess balance modifications induced by increased respiratory loads in healthy subjects

BACKGROUND

There is a link between breathing and balance and posture. When the inspiratory loads are increased by pathologies, there is a decrease of postural control. The increase of the inspiratory load on respiratory muscles is a common feature in various chronic pulmonary pathologies. Consequently, the balance of those patients is likely affected.

RESEARCH QUESTION

The aim of this study is to validate the use of the Nintendo Wii Balance Board (WBB) to assess balance modifications induced by increased respiratory loads in healthy subjects.

METHODS

Thirty-seven healthy young participants (25 ± 4 years old, 17 women) participated in this study. Five different conditions were tested: without anything (control), throughout a mouthpiece, and throughout three inspiratory threshold loads (ITL) at 10% (low), 40% (mid) and 60% (high) of the maximal inspiratory pressure. Each trial lasted for 60 s. Nine parameters were extracted based on center of pressure displacement based on a previously-validated method. ANOVA tests were used to compare the different conditions followed by Bonferroni's corrections.

RESULTS

Highly statistically significant differences (all p <  0.01) and large effect sizes (all ω² > 0.24) were obtained for all parameters between the different loads and the mouthpiece condition. There is a linear relationship between the load and balance perturbation.

SIGNIFICANCE

In this study, we demonstrated the validity of the WBB to detect the effect of the inspiratory load on balance in young healthy subjects. Further studies are needed to determine if such a kind of evaluation can be used in clinics with patients suffering from chronic respiratory disease.

Voluntary control of breathing affects center of pressure complexity during static standing in healthy older adults

Background Physiological/biomechanical systems display high degrees of complexity in their corresponding physiological and/or biomechanical outputs, indicative of normal healthy physiological functioning, though little attention has been paid to potential mechanisms which may affect complexity. Center of pressure (CoP) dynamics also display high degrees of complexity and may be affected via altered respiratory-motor interactions such as during voluntary control of breathing. Purpose The purpose of this study was to investigate the differences in the complexity of CoP dynamics during autonomous vs. voluntary control of breathing and between different voluntarily controlled breathing conditions. Methods Center of pressure recordings were taken from 18 older adults during static standing under three different breathing conditions: 1) neutral breathing, 2) abdominal breathing, and 3) thoracic breathing, the first constituting the autonomous breathing condition and the latter two constituting voluntarily controlled breathing conditions. CoP dynamics were quantified using sample entropy, standard deviation, 95% sway area, and average radial velocity. Repeated measure MANOVAs were used to assess the effect of breathing on CoP dynamics, with top-down application of ANOVAs and pairwise comparison as needed. Results Voluntary control of breathing during both conditions resulted in significantly higher CoP variability and lower sample entropy than during autonomous control of breathing in the mediolateral direction, indicating less complex dynamics and loss of system control. No significant differences between voluntary breathing conditions were observed. Conclusion Voluntary control of breathing significantly affected on CoP dynamics during static standing. The complexity of the postural control system may be affected via alterations in respiratory-motor interactions.

Proprioceptive Weighting Ratio for Balance Control in Static Standing Is Reduced in Elderly Patients With Non-Specific Low Back Pain

MINI: Elderly patients older than 65 years were divided into non-specific low back pain (NSLBP) and non-LBP (NLBP) groups. The postural control study of the relative contributions of different proprioceptive signals (relative proprioceptive weighting ratio [RPW]) revealed lower leg proprioceptive decreases (RPW 240 Hz) in NSLBP compared to NLBP.

STUDY DESIGN

A cross-sectional, observational study.

OBJECTIVE

The aim of this study was to determine a specific proprioceptive control strategy during postural balance in elderly patients with non-specific low back pain (NSLBP) and non-LBP (NLBP).

SUMMARY OF BACKGROUND DATA

Proprioceptive decline is an important risk factor for decreased balance control in elderly patients with NSLBP. The resulting reduction in proprioception in the trunk or lower legs may contribute to a reduction in postural sway. This study aims to determine the specific proprioceptive control strategy used during postural balance in elderly patients with NSLBP and NLBP and to assess whether this strategy is related to proprioceptive decline in NSLBP.

METHODS

Pressure displacement centers were determined in 28 elderly patients with NSLBP and 46 elderly patients with NLBP during upright stances on a balance board without the benefit of vision. Gastrocnemius and lumbar multifidus muscle vibratory stimulations at 30, 60, and 240 Hz, respectively, were applied to evaluate the relative contributions of the different proprioceptive signals (relative proprioceptive weighting ratio, RPW) used in postural control.

RESULTS

Compared to elderly patients with NLBP, those with NSLBP had a lower RPW at 240 Hz and significantly higher RPW at 30 Hz. A logistic regression analysis showed that RPW at 240 Hz was independently associated with NSLBP after controlling for confounding factors.

CONCLUSION

Elderly patients with NSLBP decreased their reliance on ankle strategy (RPW at 240 Hz) and hip strategy (RPW at 30 Hz) proprioceptive signals during balance control. The inability to control hip and ankle strategies indicates a deficit of postural control and is hypothesized to result from proprioceptive impairment. Moreover, elderly patients with NSLBP are at higher risk for lower leg proprioceptive decrease (240 Hz) through the NSLBP exacerbation.

LEVEL OF EVIDENCE

4.

Osteopathic Manipulative Treatment Including Specific Diaphragm Techniques Improves Pain and Disability in Chronic Nonspecific Low Back Pain: A Randomized Trial

OBJECTIVE

To investigate the effects of an osteopathic manipulative treatment (OMT), which includes a diaphragm intervention compared to the same OMT with a sham diaphragm intervention in chronic nonspecific low back pain (NS-CLBP).

DESIGN

Parallel group randomized controlled trial.

SETTING

Private and institutional health centers.

PARTICIPANTS

Participants (N=66) (18-60y) with a diagnosis of NS-CLBP lasting at least 3 months.

INTERVENTIONS

Participants were randomized to receive either an OMT protocol including specific diaphragm techniques (n=33) or the same OMT protocol with a sham diaphragm intervention (n=33), conducted in 5 sessions provided during 4 weeks.

MAIN OUTCOME MEASURES

The primary outcomes were pain (evaluated with the Short-Form McGill Pain Questionnaire [SF-MPQ] and the visual analog scale [VAS]) and disability (assessed with the Roland-Morris Questionnaire [RMQ] and the Oswestry Disability Index [ODI]). Secondary outcomes were fear-avoidance beliefs, level of anxiety and depression, and pain catastrophization. All outcome measures were evaluated at baseline, at week 4, and at week 12.

RESULTS

A statistically significant reduction was observed in the experimental group compared to the sham group in all variables assessed at week 4 and at week 12 (SF-MPQ [mean difference -6.2; 95% confidence interval, -8.6 to -3.8]; VAS [mean difference -2.7; 95% confidence interval, -3.6 to -1.8]; RMQ [mean difference -3.8; 95% confidence interval, -5.4 to -2.2]; ODI [mean difference -10.6; 95% confidence interval, -14.9 to 6.3]). Moreover, improvements in pain and disability were clinically relevant.

CONCLUSIONS

An OMT protocol that includes diaphragm techniques produces significant and clinically relevant improvements in pain and disability in patients with NS-CLBP compared to the same OMT protocol using sham diaphragm techniques.

Respiratory characteristics of individuals with non-specific low back pain: A cross-sectional study

Non-specific low back pain (NS-LBP) is known to cause respiratory dysfunction. In this study, we investigated alterations in breathing, respiratory strength and endurance, core stability, diaphragm mobility, and chest expansion among patients with NS-LBP and healthy individuals. The specific aim of the study was to correlate between respiratory function and other variables among NS-LBP patients. Thirty four patients with NS-LBP were matched with 34 healthy participants before undergoing total faulty breathing scale, spirometer, respiratory pressure meter, chest expansion, ultrasound, and pressure biofeedback measurements. There were signs of faulty breathing in the NS-LBP patients when compared to the healthy participants. Diaphragmatic mobility and respiratory muscle endurance were lower in the NS-LBP group. Chest expansion exhibited a significant decrease at the level of the fourth intercostal space in the NS-LBP group, but respiratory muscle strength and core stability were not significant between the two groups. Positive correlations were found to be fairly significant regarding respiratory muscle strength. The findings of this study indicated altered respiratory characteristics in the NS-LBP patients, and suggested that they would improve through respiratory exercises.

Proprioceptive change impairs balance control in older patients with low back pain

[Purpose] This study aims to determine the specific proprioceptive control strategy used during postural balance in older patients with low back pain (LBP) and non-LBP (NLBP) and to assess whether this strategy is related to proprioceptive decline and LBP. [Subjects and Methods] Pressure displacement center was determined in 47 older persons with LBP and 64 older persons with NLBP during upright stance on a balance board without vision. Gastrocnemius (GS) and lumbar multifidus muscle (LM) vibratory stimulations of 60 and 240-Hz, respectively, were applied to evaluate the relative contributions of different proprioceptive signals (relative proprioceptive weighting ratio, RPW) used in postural control. Age, height, weight, back muscle strength, L1/2 and L4/5 lumbar multifidus cross section area ratio, skeletal muscle mass index, sagittal vertical axis, and Roland-Morris disability questionnaire (RDQ) were evaluated. [Results] Compared with older patients with NLBP, those with LBP showed a lower RPW 240-Hz, lower L4/5 lumbar multifidus cross-sectional area ratio, and a significantly higher age and RDQ. Logistic regression analysis showed that RPW 240-Hz and age were independently associated with LBP, after controlling for confounding factors. [Conclusion] Older patients with LBP decreased their reliance on GS (RPW 240-Hz) proprioceptive signals during balance control.

The effect of inspiratory muscle training on respiratory variables in a patient with ankylosing spondylitis: A case report

Ankylosing Spondylitis (AS) presents with both musculoskeletal and cardiorespiratory pathophysiological manifestations. Inspiratory muscle training (IMT) may be a useful intervention to address deficits in respiratory and functional status.

CASE DESCRIPTION

A 25-year-old male with AS initially sought treatment for low back and right hip pain, but 7 weeks of IMT was also provided due to abnormal respiratory performance.

OUTCOMES

At baseline, the patient presented with a resting respiratory rate (RR) of 14.5 breaths/minute, tidal volume (TV) of 0.76 L, minute ventilation (VE) of 10.87 L/min, and end tidal CO2 (PetCO2) of 30.56 mmHg. Baseline exercise test results revealed a VO2max of 44 ml/kg/min and VE to CO2 output (VE/VCO2) slope of 30. Baseline MIP, SMIP, and MEP were 54 cm H2O, 507 PTU, and 87 cm H2O, respectively, and increased to 176 cm H2O, 807 PTU, and 151 cm H2O, respectively, after IMT. The VO2max increased to 51 ml/kg/min with decreases in the VE/VCO2 slope (29), resting RR (12 breaths/minute), resting TV (0.52 L), and resting VE (6.83 L/min) after IMT. Improvements during postural challenges were also observed.

DISCUSSION

This case demonstrates the clinical utility of respiratory gas analysis and respiratory performance measures to identify functional deficits and manage a patient with AS. The improvements in respiratory performance at rest, during postural challenges, and during maximal exercise after a relatively short period of IMT highlights the role IMT may have to improve functional status in patients with AS. Further investigation of IMT in patients with AS is warranted.

Chronic Pain in People With Chronic Obstructive Pulmonary Disease: Prevalence, Clinical and Psychological Implications

Background: Although pain is a common symptom in chronic obstructive pulmonary disease (COPD), pain characteristics such as frequency, duration and type are unclear. The primary study aim was to identify these pain characteristics in individuals with COPD versus healthy control participants. The secondary aim was to explore the clinical and psychological associations with pain in those with COPD. Methods: Participants with COPD and age and gender-matched, healthy controls completed questionnaires to elicit pain characteristics. Those with COPD also had assessments of dyspnea, health-related quality of life, psychological associations (anxiety and depression) and physical activity. Results: Sixty-four participants with COPD (mean [standard deviation (SD)] age 71[10] , forced expiratory volume in 1 second [FEV1] 38% predicted) and 64 control participants (mean [SD] age 67 [13] , FEV1 91% predicted) were included. Chronic pain was more prevalent in individuals with COPD compared to control participants (41% versus 29%, p=0.03). The pain was more prevalent in the chest and upper back (p=0.04). COPD participants with chest or upper back pain had a higher total lung capacity (mean difference 2.0L, 95% confidence interval [CI] 0.6 to 3.0L) compared to COPD participants without pain. Greater dyspnea (p<0.001), more depression (p=0.02) and lower physical activity levels (p=0.03) were also present in people with COPD experiencing pain. Conclusions: Chronic pain is common in COPD. It is associated with higher dyspnea and depression and lower physical activity.

"Functional" Inspiratory and Core Muscle Training Enhances Running Performance and Economy

Tong, TK, McConnell, AK, Lin, H, Nie, J, Zhang, H, and Wang, J. "Functional" inspiratory and core muscle training enhances running performance and economy. J Strength Cond Res 30(10): 2942-2951, 2016-We compared the effects of two 6-week high-intensity interval training interventions. Under the control condition (CON), only interval training was undertaken, whereas under the intervention condition (ICT), interval training sessions were followed immediately by core training, which was combined with simultaneous inspiratory muscle training (IMT)-"functional" IMT. Sixteen recreational runners were allocated to either ICT or CON groups. Before the intervention phase, both groups undertook a 4-week program of "foundation" IMT to control for the known ergogenic effect of IMT (30 inspiratory efforts at 50% maximal static inspiratory pressure [P0] per set, 2 sets per day, 6 days per week). The subsequent 6-week interval running training phase consisted of 3-4 sessions per week. In addition, the ICT group undertook 4 inspiratory-loaded core exercises (10 repetitions per set, 2 sets per day, inspiratory load set at 50% post-IMT P0) immediately after each interval training session. The CON group received neither core training nor functional IMT. After the intervention phase, global inspiratory and core muscle functions increased in both groups (p ≤ 0.05), as evidenced by P0 and a sport-specific endurance plank test (SEPT) performance, respectively. Compared with CON, the ICT group showed larger improvements in SEPT, running economy at the speed of the onset of blood lactate accumulation, and 1-hour running performance (3.04% vs. 1.57%, p ≤ 0.05). The changes in these variables were interindividually correlated (r ≥ 0.57, n = 16, p ≤ 0.05). Such findings suggest that the addition of inspiratory-loaded core conditioning into a high-intensity interval training program augments the influence of the interval program on endurance running performance and that this may be underpinned by an improvement in running economy.

The presence of respiratory disorders in individuals with low back pain: A systematic review

BACKGROUND

Inspiratory muscles, such as the diaphragm, play a key role in both respiration and spinal control. Therefore, diaphragm dysfunctions are often related to low back pain (LBP). However, few is known on the association between the presence of LBP and the presence of respiratory disorders (RD).

OBJECTIVES

To perform a systematic review on the relation between RD and LBP.

STUDY DESIGN

Systematic review.

METHODS

Two reviewers searched on PubMed/MEDLINE for studies concerning LBP and RD, from 1950 up to January 2016. The search string consisted of the following key words: low back pain, dyspnea, respiratory problems, lung diseases, comorbidity, pulmonary disease, chronic obstructive, smoking, asthma, allergy, sinusitis, respiratory tract infection and hyperventilation. The aim was to evaluate a potential correlation, co-occurrence or causality between RD and LBP.

RESULTS

A total of 16 articles were included. A significant correlation between the presence of LBP and the presence of RD such as dyspnea, asthma, different forms of allergy, and respiratory infections was found. No correlation was found between Chronic Obstructive Pulmonary Disease (COPD) and LBP, and no articles were found on the correlation between hyperventilation and LBP.

CONCLUSIONS

This is the first study providing an overview of the literature on the relation between LBP and RD. Immunological, biomechanical, psychosocial and socio-economic factors might explain this correlation. Smoking is likely to contribute. Future studies must reveal the causative relationship.

LEVEL OF EVIDENCE

Therapy, level 2a.

Test–Retest Reliability and Concurrent Validity of an fMRI-Compatible Pneumatic Vibrator to Stimulate Muscle Proprioceptors

Processing proprioceptive information in the brain is essential for optimal postural control and can be studied with proprioceptive stimulation, provided by muscle vibration, during functional magnetic resonance imaging (fMRI). Classic electromagnetic muscle vibrators, however, cannot be used in the high-strength magnetic field of the fMRI scanner. Pneumatic vibrators offer an fMRI-compatible alternative. However, whether these devices produce reliable and valid proprioceptive stimuli has not been investigated, although this is essential for these devices to be used in longitudinal research. Test–retest reliability and concurrent validity of the postural response to muscle vibration, provided by custom-made fMRI-compatible pneumatic vibrators, were assessed in a repeated-measures design. Mean center of pressure (CoP) displacements during, respectively, ankle muscle and back muscle vibration (45–60 Hz, 0.5 mm) provided by an electromagnetic and a pneumatic vibrator were measured in ten young healthy subjects. The test was repeated on the same day and again within one week. Intraclass correlation coefficients (ICC) were calculated to assess (a) intra- and interday reliability of the postural responses to, respectively, pneumatic and electromagnetic vibration, and (b) concurrent validity of the response to pneumatic compared to electromagnetic vibration. Test–retest reliability of mean CoP displacements during pneumatic vibration was good to excellent (ICCs = 0.64–0.90) and resembled that of responses to electromagnetic vibration (ICCs = 0.64–0.94). Concurrent validity of the postural effect of pneumatic vibration was good to excellent (ICCs = 0.63–0.95). In conclusion, the proposed fMRI-compatible pneumatic vibrator can be used with confidence to stimulate muscle spindles during fMRI to study central processing of proprioception.

Relationship between paraspinal muscle cross-sectional area and relative proprioceptive weighting ratio of older persons with lumbar spondylosis

[Purpose] The purpose of this study was to examine the relationship between the paraspinal muscle cross-sectional area and the relative proprioceptive weighting ratio during local vibratory stimulation of older persons with lumbar spondylosis in an upright position. [Subjects] In all, 74 older persons hospitalized for lumbar spondylosis were included. [Methods] We measured the relative proprioceptive weighting ratio of postural sway using a Wii board while vibratory stimulations of 30, 60, or 240 Hz were applied to the subjects’ paraspinal or gastrocnemius muscles. Back strength, abdominal muscle strength, and erector spinae muscle (L1/L2, L4/L5) and lumbar multifidus (L1/L2, L4/L5) cross-sectional areas were evaluated. [Results] The erector spinae muscle (L1/L2) cross-sectional area was associated with the relative proprioceptive weighting ratio during 60Hz stimulation. [Conclusion] These findings show that the relative proprioceptive weighting ratio compared to the erector spinae muscle (L1/L2) cross-sectional area under 60Hz proprioceptive stimulation might be a good indicator of trunk proprioceptive sensitivity.

Microstructural integrity of the superior cerebellar peduncle is associated with an impaired proprioceptive weighting capacity in individuals with non-specific low back pain

Introduction

Postural control is a complex sensorimotor task that requires an intact network of white matter connections. The ability to weight proprioceptive signals is crucial for postural control. However, research into central processing of proprioceptive signals for postural control is lacking. This is specifically of interest in individuals with non-specific low back pain (NSLBP), because impairments in postural control have been observed as possible underlying mechanisms of NSLBP. Therefore, the objective was to investigate potential differences in sensorimotor white matter microstructure between individuals with NSLBP and healthy controls, and to determine whether the alterations in individuals with NSLBP are associated with the capacity to weight proprioceptive signals for postural control.

Methods

The contribution of proprioceptive signals from the ankle and back muscles to postural control was evaluated by local muscle vibration in 18 individuals with NSLBP and 18 healthy controls. Center of pressure displacement in response to muscle vibration was determined during upright standing on a stable and unstable support surface. Diffusion magnetic resonance imaging was applied to examine whether this proprioceptive contribution was associated with sensorimotor white matter microstructure.

Results

Individuals with NSLBP showed a trend towards a reduced fractional anisotropy along the left superior cerebellar peduncle compared to healthy controls (p = 0.039). The impaired microstructural integrity of the superior cerebellar peduncle in individuals with NSLBP was significantly correlated with the response to ankle muscle vibration (p<0.003).

Conclusions

In individuals with NSLBP, a decreased integrity of the superior cerebellar peduncle was associated with an increased reliance on ankle muscle proprioception, even on unstable support surface, which implies an impaired proprioceptive weighting capacity. Our findings emphasize the importance of the superior cerebellar peduncle in proprioceptive weighting for postural control in individuals with NSLBP.

Cumulative mechanical low-back load at work is a determinant of low-back pain

OBJECTIVES

Reported associations of physical exposures during work (eg, lifting, trunk flexion or rotation) and low-back pain (LBP) are rather inconsistent. Mechanical back loads (eg, moments on the low back) as a result of exposure to abovementioned risk factors have been suggested to be important as such loads provide a more direct relationship with tissue failure and thus LBP. Since information on the effect of such load metrics with LBP is lacking yet, we aimed to assess this effect in a prospective study.

METHODS

Of 1131 workers, categorised into 19 groups, LBP was prospectively assessed over 3 years. Video and hand force recordings of 4-5 workers per group (93 in total) were used to estimate mechanical low-back loads (peak load and three cumulative load metrics, ie, linear weighted load, squared weighted load and load weighted to the tenth power) during manual materials handling (MMH) tasks using a video analysis method. These data were combined with static mechanical load estimates based on structured observation of non-MMH tasks. Associations of mechanical loads and LBP were tested using generalised estimating equations.

RESULTS

Significant effects on LBP were found for cumulative low-back moments (linear and squared weighted; both p<0.01 and ORs of 3.01 and 3.50, respectively) but not for peak and cumulative moments weighted to the tenth power.

CONCLUSIONS

Results of this first prospective study on the effect of mechanical low-back load on LBP support a LBP aetiology model of cumulative loads, potentially due to accumulation of microdamage or fatigue. Therefore, prevention of LBP should focus on reducing cumulative low-back loads, especially in highly exposed occupational groups, for example, by reducing handling of heavy loads and working in awkward body postures.

Postural strategy and back muscle oxygenation during inspiratory muscle loading

PURPOSE

Most healthy individuals show a multisegmental control strategy during challenging standing conditions, whereas others show a rigid ankle-steered strategy, which is assumed as suboptimal. Respiratory-demanding tasks exert a perturbing effect on balance, although the underlying mechanisms remain poorly understood. The purpose of this study was to investigate whether inspiratory resistive loading (IRL) affects postural strategy, back muscle oxygenation, and blood volume during postural control.

METHODS

We assessed the acute effects of increased respiratory effort by measuring the center of pressure displacement in 12 healthy individuals during upright standing on an unstable support surface while breathing against an IRL. Simultaneous ankle and back muscle vibration was used to evaluate the proprioceptive strategy (multisegmental vs ankle-steered) during postural control. Back muscles oxygenation and blood volume were assessed using near-infrared spectroscopy (tissue oxygenation index, deoxyhemoglobin, oxyhemoglobin, and combined hemoglobin).

RESULTS

An increased proprioceptive gain at the ankles and an decreased gain at the back were observed after approximately 7 min of IRL. Retrospectively, the group was subdivided on the basis of the participants' dominant proprioceptive use during a baseline postural control. During IRL, the ankle-steered group showed an increased reliance on ankle proprioception compared with a multisegmental group (-5.9 ± 3.1 and 1.0 ± 1.9 cm, respectively, P < 0.05). Tissue oxygenation index, deoxyhemoglobin, oxyhemoglobin, and combined hemoglobin declined progressively in the ankle-steered group during the IRL (from baseline (100%) to -1%, -1%, -45%, and -18%, respectively, P < 0.05), whereas no decline was found in the multisegmental group (from baseline (100%) to 134%, 82%, 129%, and 153%, respectively, P > 0.05).

CONCLUSION

Individuals who adopted an ankle-steered strategy during IRL showed a progressive decline in back muscle oxygenation and blood volume. In contrast, IRL did not affect back muscle oxygenation and blood volume in individuals who showed a multisegmental strategy in upright standing.