The relationship between psychological factors and performance on the Biering-Sørensen back muscle endurance test

Can intermittent changes in trunk extensor muscle length delay muscle fatigue development?

Muscle length changes may evoke alternating activity and consequently reduce local fatigue and pain during prolonged static bending. The aim of this study was to assess whether a postural intervention involving intermittent trunk extensor muscle length changes (INTERMITTENT) can delay muscle fatigue during prolonged static bending when compared to a near-isometric condition (ISOMETRIC) or when participants were allowed to voluntarily vary muscle length (VOLUNTARY). These three conditions were completed by 11 healthy fit male participants, in three separate sessions of standing with 30 ± 3 degrees trunk inclination until exhaustion. Conventional and high-density electromyography (convEMG and HDsEMG, respectively) were measured on the left and right side of the spine, respectively. The endurance time for INTERMITTENT was 33.6% greater than ISOMETRIC (95% CI: [3.8, 63.5]; p = 0.027) and 29.4% greater than VOLUNTARY (95% CI: [7.0, 51.7]; p = 0.010), but not different between ISOMETRIC and VOLUNTARY. The convEMG and HDsEMG amplitude coefficient of variation was significantly greater for INTERMITTENT versus ISOMETRIC. The rate of change in convEMG and HDsEMG spectral content did not reveal significant differences between conditions as found in endurance time. Additional regression analyses between endurance time and rate of change in convEMG (p > 0.05) and HDsEMG (R2 = 0.39-0.65, p = 0.005-0.039) spectral content indicated that HDsEMG better reflects fatigue development in low-level contractions. In conclusion, imposed intermittent trunk extensor muscle length changes delayed muscle fatigue development when compared to a near-isometric condition or when participants were allowed to voluntarily vary muscle length, possibly due to evoking alternating activity between/within trunk extensor muscles.

The effect of back muscle fatigue on EMG and kinematics based estimation of low-back loads and active moments during manual lifting tasks

This study investigated the effects of back muscle fatigue on the estimation of low-back loads and active low-back moments during lifting, using an EMG and kinematics based model calibrated with data from an unfatigued state. Fourteen participants performed lifting tasks in unfatigued and fatigued states. Fatigue was induced through semi-static forward bending. EMG, kinematics, and ground reaction forces were measured, and low-back loads were estimated using inverse dynamics and EMG-driven muscle model. A regression model was developed using data from a set of calibration lifts, and its accuracy was evaluated for unfatigued and fatigued lifts. During the fatigue-inducing task, the EMG amplitude increased by 2.8 %MVC, representing a 38% increase relative to the initial value. However, during the fatigued lifts, the peak EMG amplitude was found to be 1.6 %MVC higher than that observed during the unfatigued lifts, representing a mere 4% increase relative to the baseline unfatigued peak EMG amplitude. Kinematics and low-back load estimates remained unaffected. Regression model estimation errors remained unaffected for 5 kg lifts, but increased by no more than 5% of the peak active low-back moment for 15 kg lifts. We conclude that the regression-based estimation quality of active low-back moments can be maintained during periods of muscle fatigue, although errors may slightly increase for heavier loads.

Adults with lower-limb amputation: Reduced multifidi muscle activity and extensor muscle endurance is associated with worse physical performance

Trunk muscles may be an overlooked region of deficits following lower-limb amputation (LLA). This study sought to determine the extent that trunk muscle deficits are associated with physical function following amputation. Sedentary adults with a unilateral transtibial- (n = 25) or transfemoral-level (n = 14) amputation were recruited for this cross-sectional research study. Participants underwent a clinical examination that included ultrasound imaging of the lumbar multifidi muscles, the modified Biering-Sorensen Endurance Test (mBSET), and performance-based measures, that is, the Timed Up and Go (TUG), Berg Balance Scale (BBS), and 10-m Walk Test (10mWT). Associations between trunk muscle metrics and performance were explored with regression modeling, while considering covariates known to impact performance postamputation (p ≤ 0.100). Average ultrasound-obtained, lumbar multifidi activity was 14% and 16% for transfemoral- and transtibial-level amputations, respectively, while extensor endurance was 37.34 and 12.61 s, respectively. For TUG, nonamputated-side multifidi activity and an interaction term (level x non-amputated-side multifidi activity) explained 9.4% and 6.2% of the total variance, respectively. For 10mWT, beyond covariates, non-amputated-side multifidi activity and the interaction term explained 6.1% and 5.8% of the total variance, respectively. For TUG, extensor endurance and an interaction term (level x mBSET) explained 11.9% and 8.3% of the total variance beyond covariates; for BBS and 10mWT, extensor endurance explained 11.2% and 17.2% of the total variance, respectively. Findings highlight deficits in lumbar multifidi activity and extensor muscle endurance among sedentary adults with a LLA; reduced muscle activity and endurance may be important factors to target during rehabilitation to enhance mobility-related outcomes.

The effect of skilled motor training on corticomotor control of back muscles in different presentations of low back pain

Transcranial magnetic stimulation (TMS) has revealed differences in the motor cortex (M1) between people with and without low back pain (LBP). There is potential to reverse these changes using motor skill training, but it remains unclear whether changes can be induced in people with LBP or whether this differs between LBP presentations. This study (1) compared TMS measures of M1 (single and paired-pulse) and performance of a motor task (lumbopelvic tilting) between individuals with LBP of predominant nociceptive (n = 9) or nociplastic presentation (n = 9) and pain-free individuals (n = 16); (2) compared these measures pre- and post-training; and (3) explored correlations between TMS measures, motor performance, and clinical features. TMS measures did not differ between groups at baseline. The nociplastic group undershot the target in the motor task. Despite improved motor performance for all groups, only MEP amplitudes increased across the recruitment curve and only for the pain-free and nociplastic groups. TMS measures did not correlate with motor performance or clinical features. Some elements of motor task performance and changes in corticomotor excitability differed between LBP groups. Absence of changes in intra-cortical TMS measures suggests regions other than M1 are likely to be involved in skill learning of back muscles.

Reduction in pain-related fear is not associated with improvement in spinal biomechanics but with decrease in movement-evoked pain in patients with chronic low back pain

BACKGROUND AND AIMS

While a causal relationship between pain-related fear and spinal movement avoidance in patients with chronic low back pain (CLBP) has frequently been postulated, evidence supporting this relationship is limited. This study aimed to test if decreases in pain-related fear or catastrophizing were associated with improvements in spinal biomechanics, accounting for possible changes in movement-evoked pain.

METHODS

Sixty-two patients with CLBP were assessed before and after an interdisciplinary rehabilitation program (IRP). Pain-related fear was assessed with general and task-specific measures. Lower and upper lumbar angular amplitude and velocity as well as paraspinal muscle activity were recorded during five daily-life tasks to evaluate spinal biomechanics. Relationships were tested with multivariable linear regression analyses.

RESULTS

The large decreases in pain-related fear and catastrophizing following the IRP were scarcely and inconsistently associated with changes in spinal biomechanics (< 3% of the models reported a statistically significant association). Results remained comparable for activities inducing more or less fear, for specific or general measures of pain-related fear, and for analyses performed on the entire population or limited to subgroups of patients with higher levels of task-specific fear. In contrast, reductions in task-specific pain-related fear were significantly associated with decreases in movement-evoked pain in all tasks (r = 0.26-0.62, p ≤ 0.02).

CONCLUSION

This study does not support an association between pain-related fear and spinal movement avoidance. However, it provides evidence supporting a direct relationship between decreased pain-related fear and decreased movement-evoked pain, possibly explaining some mechanisms of the rehabilitation programs.

Trunk muscle function and its association with functional limitations in sedentary occupation workers with and without chronic nonspecific low back pain

BACKGROUND

The function of trunk muscles in chronic nonspecific low back pain (CNLBP) is controversially discussed, and trunk muscle function in sedentary occupation workers is poorly understood.

OBJECTIVE

To investigate whether muscle function differs between sedentary occupation workers with and without CNLBP and to determine the association between functional limitations and muscle function.

METHODS

This study included 32 sedentary occupation workers (16 workers with CNLBP and 16 age- and sex-matched workers without CNLBP). Group differences in isokinetic trunk flexion-extension strength, muscle cocontraction, endurance time (Biering-Sorensen test) and electromyographic muscle fatigue were assessed. The association of these parameters and Oswestry Disability Index (ODI) score were examined in the CNLBP group.

RESULTS

Participants with CNLBP had lower trunk extensor (-20%) and flexor (-18%) strength and less cocontraction (-22%) than participants without CNLBP, but due to large variability in both groups these differences were not statistically significant. Trunk muscle endurance and fatigue were comparable between groups. Variance in endurance time explained 28% of variance in the ODI-score in the CNLBP group (R2= 0.277).

CONCLUSIONS

In patients with CNLBP, greater functional disability was associated with lower endurance. Further evidence is necessary to elucidate whether specifically training endurance performance may be beneficial for sedentary occupation workers.

Multicomponent exercises to prevent and reduce back pain in elderly care nurses: a randomized controlled trial

Background

Sports science is making an important contribution to health services research and supports the development of tailored interventions, e.g., in nursing settings. Working in elderly care is associated with a high prevalence of low back pain (LBP). Due to the diverse requirements and high strains, multicomponent programs are essential to address all relevant factors. This randomized controlled trial investigated the effects of a tailored ten-week ergonomics and twelve-week strength training on lifting behavior, strength endurance, LBP, functional impairment and adherence.

Methods

n = 42 nurses were randomly assigned to the intervention (IG; n = 20) or control group (CG; n = 22). They were eligible for participation if they were active in residential care and if they provided written informed consent. Other employees were excluded. The data were collected at baseline, at ten weeks (after ergonomics training), at 22 weeks (after strength training), and at 34 weeks (follow-up). The analysis combined physical tests with questionnaires (Progressive Isoinertial Lifting Evaluation, PILE-Test; Biering-Sørensen-Test; Visual Analog Scale Pain, VAS; Oswestry Disability Index, ODI; self-developed questionnaire for adherence). Group differences were analyzed by Chi²-Tests, ANOVA, and Linear Mixed Models.

Results

The IG showed an improved lifting performance (PILE-Test; 95% CI 1.378–7.810, p = .006) and a reduced LBP compared to the CG (VAS; 95% CI − 1.987 to 0.034, p = .043) after ergonomics training (PILE-Test, F_(1,34) = 21.070, p < .001; VAS, F_(1,34) = 5.021, p = .032). The results showed no differences concerning the Biering-Sørensen-Test and the ODI. Positive adherence rates were observed.

Conclusions

This approach and the positive results are essential to derive specific recommendations for effective prevention. The study results can be completed in future research with additional strategies to reduce nurses’ burden further.

Trial registration

The trial was registered at DRKS.de (DRKS00015249, registration date: 05/09/2018).

No alteration of back muscle oxygenation during isometric exercise in individuals with non-specific low back pain

The aim of our study was (I) To compare back muscle oxygenation and perfusion as well as Biering–Sorensen muscle endurance (BSME) test holding times between chronic non-specific low back pain (CNSLBP) patients and asymptomatic controls matched for age, body mass index (BMI), sex and physical activity, and (II) to investigate factors associated with BSME holding times. Muscle perfusion (tHb) and oxygenation (SmO₂) were measured by near-infrared spectroscopy (NIRS) based oximetry in three back muscles during the BSME. Reliability of tHb and SmO₂ was assessed in a separate sample. BSME holding time and SmO₂ were compared between patients (n = 45) and controls (n = 45) and factors associated with BSME holding time were assessed using multiple linear regression. Reliability for SmO₂ was excellent (ICC = 0.87–0.99). THb showed poor to moderate reliability and was not further used. Groups differed for BSME holding time (P = 0.03), pain intensity (P ≤ 0.0005) and subcutaneous tissue thickness (P = 0.01) but not for NIRS measures. Physical activity and BMI were associated with BSME holding times. Insufficient muscle oxygenation does not seem to be a major factor contributing to CNSLBP. Future investigation should evaluate other determinants of BSME holding times, such as motivation and recruitment of auxiliary muscles.

Paraspinal strength and electromyographic fatigue in patients with sub-acute back pain and controls: Reliability, clinical applicability and between-group differences

BACKGROUND

Paraspinal muscle strength and fatigue are considered important in low back pain (LBP) prevention and rehabilitation. High reliability of paraspinal strength and electromyographic (EMG)-fatigue parameters has not been universally reported. Moreover, the discriminative validity of these parameters requires further exploration, under the threat of potentially poor reliability of the methods examined.

AIM

To investigate the reliability and discriminative validity of paraspinal strength and EMG-related fatigue in subjects with recurrent LBP and healthy participants.

METHODS

Test-retest measurements were performed in 26 healthy and 66 LBP volunteers, for reliability. Paraspinal isometric maximal and mean strength were determined with a maximum voluntary isometric contraction (MVIC) protocol, performed in a custom-made device. For the fatigue test, participants performed a 60% MIVC level continuous isometric contraction of the paraspinals, in conjunction with EMG analysis from 4 muscle sites of the lumbar spine. Initial median frequency (IMF), the median frequency slope (MFslope), as well as the root mean square (RMS) slope EMG parameters were used as fatigue measures. Data were analysed with repeated measures ANOVA for test-retest differences. For reliability, the intraclass correlation coefficient (ICC_3,1), standard error of the measurement (SEM) and the smallest detectable difference (SDD) were reported. Group-related differences for fatigue measures were analysed with a Multivariate Analysis of Covariance, with age, weight and strength as covariates.

RESULTS

Isometric strength presented statistically significant between-day differences (P < 0.01), however these did not exceed 10% (healthy: 7.2%/LBP-patients: 9.7%) and ICC reliability values were excellent, yet test-retest error was increased for the patient group (healthy: ICC_3,1: 0.92-0.96, SEM: 5.72-5.94 Hz, SDD: 18.51%-18.57%/LBP-patients: ICC_3,1: 0.91-0.96, SEM: 6.49-6.96, SDD: 30.75%-31.61%). For the frequency data, IMF reliability was excellent (healthy: ICC_3,1: 0.91-0.94, SEM: 3.45-7.27 Hz, SDD: 9.56%-20.14%/patients: ICC_3,1: 0.90-0.94, SEM: 6.41-7.59 Hz, SDD: 17.75%-21.02%) and of MF raw and normalised slopes was good (healthy: ICC_3,1: 0.78-0.82, SEM: 4.93-6.02 Hz, SDD: 13.66-16.67%/LBP-patients: ICC_3,1: 0.83-0.85, SEM: 6.75-7.47 Hz, SDD: 18.69%-20.69%). However, the reliability for RMS data presented unacceptably high SDD values and were not considered further. For discriminative validity, less MVIC and less steep MFslopes were registered for the patient group (P < 0.01).

CONCLUSION

Reliability and discriminative ability of paraspinal strength and EMG-related frequency parameters were demonstrated in healthy participants and patients with LBP.

Characterisation of motor cortex organisation in patients with different presentations of persistent low back pain

Persistence of low back pain is thought to be associated with different underlying pain mechanisms, including ongoing nociceptive input and central sensitisation. We hypothesised that primary motor cortex (M1) representations of back muscles (a measure of motor system adaptation) would differ between pain mechanisms, with more consistent observations in individuals presumed to have an ongoing contribution of nociceptive input consistently related to movement/posture. We tested 28 participants with low back pain sub-grouped by the presumed underlying pain mechanisms: nociceptive pain, nociplastic pain and a mixed group with features consistent with both. Transcranial magnetic stimulation was used to study M1 organisation of back muscles. M1 maps of multifidus (deep and superficial) and longissimus erector spinae were recorded with fine-wire electromyography and thoracic erector spinae with surface electromyography. The nociplastic pain group had greater variability in M1 map location (centre of gravity) than other groups (p < .01), which may suggest less consistency, and perhaps relevance, of motor cortex adaptation for that group. The mixed group had greater overlap of M1 representations between deep/superficial muscles than nociceptive pain (deep multifidus/longissimus: p = .001, deep multifidus/thoracic erector spinae: p = .008) and nociplastic pain (deep multifidus/longissimus: p = .02, deep multifidus/thoracic erector spinae: p = .02) groups. This study provides preliminary evidence of differences in M1 organisation in subgroups of low back pain classified by likely underlying pain mechanisms. Despite the sample size, differences in cortical re-organisation between subgroups were detected. Differences in M1 organisation in subgroups of low back pain supports tailoring of treatment based on pain mechanism and motor adaptation.

Motor performance and back pain in children and adolescents: A systematic review

BACKGROUND AND OBJECTIVE

Motor performance during childhood and adolescence is recognized as a relevant determinant of present and future health, but its effects on back pain (BP) remain unclear. In this systematic review, we aimed to identify the association between motor performance and BP in children and adolescents.

DATABASES AND DATA TREATMENT

A literature search was performed in the MEDLINE, Scopus, Embase, SPORTDiscus and CINAHL databases. We included cross-sectional, cohort, case-control and controlled clinical trials (data from control groups). The inclusion criteria were as follows: (a) participants aged 6-19 years; (b) assessment motor performance components; (c) assessment of BP and (d) reported measures of association. The risk of bias was assessed by the Downs and Black instrument and the quality of evidence by the grading of recommendations, assessment, development and evaluation (GRADE).

RESULTS

A total of 2360 articles were identified, 25 of which were included in our systematic review. Of the 25 studies, 19 were evaluated as having a low risk of bias. GRADE indicated that 20 studies presented low or very low quality. Most of the studies evaluated flexibility (n = 16), muscle endurance (n = 18) and muscle strength (n = 9). Aerobic capacity, balance and speed were also examined in some studies (n < 5). Overall, motor performance (flexibility, muscle endurance, muscle strength, aerobic capacity, balance and speed) was not associated with BP. Most of the results were inconsistent because of the lack of studies, risk of bias and low quality of evidence. Only trunk extensor muscle endurance was associated with decreased BP with moderate quality of the supporting evidence. Prospective studies with a low risk of bias are warranted to further clarify this relationship in childhood and adolescence and findings may support more targeted and effective health promotion interventions.

SIGNIFICANCE

This systematic review shows that motor performance (flexibility, muscle endurance, muscle strength, aerobic capacity, balance and speed) was not associated with BP in children and adolescents. Most of the results were inconsistent because of the lack of studies, risk of bias and low quality of evidence. Only trunk extensor muscle endurance was associated with decreased BP with moderate quality of supporting evidence.

Multiple measures of muscle function influence Sorensen Test performance in individuals with recurrent low back pain

BACKGROUND

Sorensen Test time-to-task-failure (TTF) predicts several low back pain (LBP) clinical outcomes, including recurrence. Because the test is described as a measure of trunk extensor (TE) muscle endurance, LBP rehabilitation programs often emphasize endurance training, but the direct role of TE muscle function on Sorensen Test-TTF remains unclear.

OBJECTIVE

To assess the discriminative and associative properties of multiple markers of isolated TE performance with regard to Sorensen Test-TTF in individuals with recurrent LBP.

METHOD

Secondary analysis of baseline measures from participants in a registered (NCT02308189) trial (10 men; 20 women) was performed. Participants were classified by Sorensen Test-TTF as high, moderate or low risk for subsequent LBP episodes, and compared to determine if classification could discriminate differences in TE function. Correlations between Sorensen Test-TTF and isolated TE performance, anthropometrics and disability were investigated.

RESULTS

Individuals at risk of subsequent LBP episodes had greater perceived disability and fat mass/TE strength ratios (P⩽ 0.05) than those not at risk. Modest, significant (r= 0.36-0.42, P⩽ 0.05) associations were found between Sorensen Test-TTF, TE endurance and fat mass/TE strength. Exploratory analyses suggested possible sex-specific differences related to Sorensen Test-TTF.

CONCLUSIONS

Isolated TE muscle endurance is only one of several factors with similar influence on Sorensen Test-TFF, thus LBP rehabilitation strategies should consider other factors, including TE strength, anthropometrics and perceived disability.

Trunk muscle endurance, strength and flexibility in rural subsistence farmers and urban industrialized adults in western Kenya

OBJECTIVES

High trunk muscle endurance, strength, and moderate flexibility reportedly help maintain musculoskeletal health, but there is evidence for tradeoffs among these variables as well as sex differences in trunk muscle endurance and strength. To test if these observations extend similarly to both men and women in nonindustrial and industrial environments, we investigated intra-individual associations and group and sex differences in trunk muscle endurance, strength, and flexibility among 74 (35 F, 39 M; age range: 18-61 years) adults from the same Kalenjin-speaking population in western Kenya. We specifically compared men and women from an urban community with professions that do not involve manual labor with rural subsistence farmers, including women who frequently carry heavy loads.

METHODS

Trunk muscle endurance, strength, and flexibility were measured with exercise tests and electromyography (EMG).

RESULTS

We found a positive correlation between trunk extensor strength and endurance (R = .271, p ≤ .05) and no associations between strength or endurance and flexibility. Rural women had higher trunk extensor and flexor endurance, EMG-determined longissimus lumborum endurance, and trunk extensor strength than urban women (all p ≤ .05). Rural women had higher trunk extensor and flexor endurance than rural men (both p ≤ .05). Urban women had lower trunk flexor and extensor endurance than urban men (both p ≤ .01).

CONCLUSIONS

High levels of physical activity among nonindustrial subsistence farmers, particularly head carrying among women, appear to be associated with high trunk muscle endurance and strength, which may have important benefits for helping maintain musculoskeletal health.

Relationship between psychological factors and spinal motor behaviour in low back pain: a systematic review and meta-analysis

ABSTRACT

This meta-analysis investigated whether more negative psychological factors are associated with less spinal amplitude of movement and higher trunk muscle activity in individuals with low back pain. Furthermore, it examined whether pain intensity was a confounding factor in this relationship. We included studies that provided at least 1 correlation coefficient between psychological (pain-related fear, catastrophizing, depression, anxiety, and self-efficacy) and spinal motor behaviour (spinal amplitude and trunk muscle activity) measures. In total, 52 studies (3949 participants) were included. The pooled correlation coefficients (95% confidence interval; number of participants) were -0.13 (-0.18 to -0.09; 2832) for pain-related fear, -0.16 (-0.23 to -0.09; 756) for catastrophizing, -0.08 (-0.13 to -0.03; 1570) for depression, -0.08 (-0.30 to 0.14; 336) for anxiety, and -0.06 (-0.46 to 0.36; 66) for self-efficacy. The results indicated that higher levels of pain-related fear, catastrophizing, and depression are significantly associated with reduced amplitudes of movement and larger muscle activity and were consistent across subgroup and moderation analyses. Pain intensity did not significantly affect the association between these psychological factors and spinal motor behaviour and had a very small independent association with spinal motor behaviour. In conclusion, the very small effect sizes found in the meta-analyses question the role of psychological factors as major causes of spinal movement avoidance in low back pain. Experimental studies with more specific and individualized measures of psychological factors, pain intensity, and spinal motor behaviour are recommended.

Relationship between psychosocial factors and objective physical function in special needs school staff members suffering from low back pain

Physical function impairment in patients with low back pain (LBP) occurs due to the influence of psychosocial factors. Only a few studies have objectively evaluated physical function. We aimed to objectively assess the physical functions of individuals subjects with LBP, and clarify the association between physical function and psychosocial factors. We enrolled 411 individuals with LBP working in special needs schools. We examined their degree of pain, and the psychosocial factors strength through the STarT Back Tool, which categorized them into the low-risk, medium-risk, and high-risk groups. We assessed their abdominal muscle endurance, lower limb muscle strength, and hip joint flexibility. The relationships between these physical functions and psychosocial factors were analyzed by logistic regression models. Those in the high-risk group had significantly lower abdominal muscle and lower limb muscle strength (p<0.001). After adjusting for confounding factors, the odds ratios of the high-risk compared to the low-risk group for low abdominal muscle endurance, lower limb muscle strength, and restricted right and left Straight Leg Raising were 5.47, 3.14, 2.65, and 3.12, respectively (95% CIs: 2.35-12.74, 1.43-6.89, 1.08-6.55, and 1.20-8.11, respectively). Therefore, the low physical function observed in the high-risk group was associated with their psychosocial factors.

Muscular Fitness and Work Ability among Physical Therapists

The Work Ability Index (WAI) is a validated and widely used tool in occupational research. However, normative values for physical therapists (PTs) by age and sex are lacking. Although the nature of PTs' work is physically demanding, it is unknown whether muscular fitness is associated with their WAI. This study sought to provide reference WAI data for Spanish PTs and to evaluate the association between PTs' muscular fitness and WAI. Data on WAI of 1005 PTs were collected using a questionnaire. A subgroup (n = 68) performed a battery of physical tests including grip strength, push-ups and back-extension endurance. Associations between muscular fitness and WAI were evaluated using logistic regression controlling for various confounders. PTs aged 50 years or older had lower WAI scores than their younger counterparts. PTs with high back-extension endurance scored 3.5 (95% CI) higher in the WAI than those with low endurance. No associations were found between grip strength or number of push-ups and WAI. Our findings seem to highlight the importance of muscular fitness in PTs, especially the back-extension endurance.

Surface Electromyography in Clinical Practice. A Perspective From a Developing Country

Surface electromyography (sEMG) has long been used in research, health care, and other fields such as ergonomics and brain-machine interfaces. In health care, sEMG has been employed to diagnose as well as to treat musculoskeletal disorders, pelvic floor dysfunction, and post-stroke motor deficits, among others. Despite the extensive literature on sEMG, the clinical community has not widely adopted it. We believe that in developing countries, such as Chile, this phenomenon may be explained by several interacting barriers. First, the socioeconomics of the country creates an environment where only high cost-effective treatments are routinely applied. Second, the majority of the sEMG literature on clinical applications has not extensively translated into decisive outcomes, which interferes with its applicability in low-income contexts. Third, clinical training on rehabilitation provides inadequate instruction on sEMG. And fourth, accessibility to equipment (i.e., affordability, availability, portability) may constitute another barrier, especially among developing countries. Here, we analyze socio-economic indicators of health care in Chile and comment on current literature about the use of sEMG in rehabilitation. Then we analyze the curricula of several physical therapy schools in Chile and report some estimations of the training on sEMG. Finally, we analyze the accessibility of some available sEMG devices and show that several match predefined criteria. We conclude that in developing countries, the insufficient use of sEMG in health might be explained by a shortage of evidence showing a crucial role in specific outcomes and the lack of training in rehabilitation-related careers, which interact with local socioeconomic factors that limit the application of these techniques.

The Relevance of Dual Tasking for Improving Trunk Muscle Endurance After Back Surgery

OBJECTIVE

To determine the effect of dual tasking on trunk muscle endurance in patients after lumbar diskectomy.

DESIGN

Cross-sectional study.

SETTING

Rehabilitation hospital setting.

PARTICIPANTS

Individuals (N=14) undergoing primary lumbar diskectomy.

INTERVENTION

Using a randomized design on 2 separate days, muscle endurance was evaluated during prone bridging and Biering-Sorensen tests. Each test was randomly performed under 2 cognitive conditions: single task without cognitive condition and self-regulated dual task (ie, mathematical task).

MAIN OUTCOME MEASURES

The primary outcomes were time to failure and pain assessed by the visual analog scale from 0 to 100 mm. The secondary outcomes were kinesiophobia assessed by the Tampa Scale and disability assessed by the Oswestry Disability Index. Associations were tested using a repeated measures analysis of variance with relevant interaction test.

RESULTS

A significant interaction between condition, endurance tests, and kinesiophobia (P=.005) was found. The post hoc comparison showed positive effects between cognitive conditions in both endurance tests (prone bridging test: mean difference, 15.7s; 95% confidence interval [CI], 7.5-24s; P=.001; Biering-Sorensen test: mean difference, 7.9s; 95% CI, 1.9-14s; P=.014). The linear regression analysis between the Tampa Scale for Kinesiophobia and the difference of time to failure between cognitive conditions showed a positive correlation only during the Biering-Sorensen test (r=0.80; P=.001).

CONCLUSIONS

A self-regulated dual task increases trunk muscle endurance in patients after lumbar diskectomy. The results suggest that the difference observed in time to failure between the single task and dual task is associated with fear avoidance, especially during back extension. This strategy seems especially relevant for patients with high levels of fear avoidance and may be used to improve trunk muscle endurance.

Effect of a brief progressive resistance training program in hospital porters on pain, work ability, and physical function

BACKGROUND

Hospital porters are possibly exposed to the greatest mechanical loads within the hospital environment. However, the evidence about preventive strategies in this population is scarce.

OBJECTIVE

To investigate the effect of a workplace-based progressive resistance-training program on musculoskeletal pain among hospital porters.

METHOD

A total of 37 hospital porters (27 women, 10 men) participated. Participants allocated to the intervention group performed five brief resistance training sessions/week, for 9 weeks during working hours at the hospital. Intensity was progressively increased. Participants allocated to the control group maintained their usual physical activity. The primary outcome was pain assessed with the patient global impression of pain change scale. Secondary outcome measures were average pain intensity, work ability, use of analgesics, and physical function. Additionally, perceived general changes were evaluated at follow-up: wellness, satisfaction at work, desire to exercise, motivation to eat healthy, energy to be with family and friends, and socialization with colleagues.

RESULTS

For the primary outcome, the intervention group showed lower general pain (p < 0.0001) and greater wellbeing (p < 0.0001), work satisfaction (p = 0.0048), desire for practicing exercise (p = 0.0007), and energy (p = 0.0474) compared with the control group. Significant between-group interactions were found for work impairment due to diseases (d = -1.2), hips/thighs pain (d = 0.7), ankles/feet pain (d = 0.4), the Biering-Sorensen test (d = -0.6) and the push-ups test (d = -2.3) favoring the intervention group. All between-group differences were clinically important.

CONCLUSION

A progressive resistance training program performed at the workplace is feasible and effective in reducing musculoskeletal pain and improving work ability and physical function among hospital porters.

Feasibility and Reliability of Functional Muscle Tests in Lung Transplant Recipients

Supplemental digital content is available in the text.

Objective

This study investigates the feasibility, reliability, and correlations of recommended functional tests in lung transplant recipients shortly after surgery.

Design

This is an observational study.

Methods

Fifty patients (28 females) performed well-standardized maximum isometric back extension in a sitting position, handgrip strength, and Biering-Sørensen endurance tests shortly before discharge from the acute hospital, shortly thereafter, and 2 mos later after subacute rehabilitation.

Results

Back extension testing was well feasible, but only two thirds of the patients could perform the Biering-Sørensen test at baseline and they experienced a greater number of minor but no major adverse events. Absolute reliability measures and the intraclass correlation coefficients were excellent for the strength (0.97–0.98 [0.95–0.99]) and good for the endurance tests (0.69 [0.26–0.87]). Handgrip revealed high correlation with back strength (≥0.75) but not with Biering-Sørensen scores.

Conclusions

Well-controlled maximum back strength testing is feasible and reliable, and the scores are highly correlated with grip strength in lung transplant recipients shortly before hospital discharge. The Biering-Sørensen test should be limited to patients without dominant weakness and/or fear. Future research should investigate whether grip instead of back extension strength can safely be used for proper exercise prescription.

Sørensen test performance is driven by different physiological and psychological variables in participants with and without recurrent low back pain

Time to task failure (TTF) on the Sørensen test predicts low back pain (LBP), but mechanisms driving TTF may vary in those with and without recurrent LBP. To determine the physiological and psychological predictors of TTF, 48 sex, age, and BMI matched participants (24 Healthy, 24 LBP) completed psychological surveys, maximal strength assessments, and the Sørensen test. A two-way ANOVA revealed no significant effects of group (p = 0.75) or sex (p = 0.21) on TTF. In the full sample, linear regression analyses revealed that normalized Median Power Frequency (MPF) slope of the Erector Spinae (β = 0.350, p < 0.01), the Biceps Femoris (β = 0.375, p < 0.01), and self-efficacy (β = 0.437, p < 0.01) predicted TTF. In the Healthy group, normalized MPF slope of the Erector Spinae (β = 0.470, p < 0.01), the Biceps Femoris (β = 0.437, p < 0.01), and self-efficacy (β = 0.330, p = 0.02) predicted TTF. In the LBP group, trunk mass (β = -0.369, p = 0.04) and self-efficacy (β = 0.450, p = 0.02) predicted TTF. In sum, self-efficacy consistently predicts performance, while trunk mass appears to negatively influence TTF only for those with recurrent LBP.

Determining Physiological and Psychological Predictors of Time to Task Failure on a Virtual Reality Sørensen Test in Participants With and Without Recurrent Low Back Pain: Exploratory Study

BACKGROUND

Sørensen trunk extension endurance test performance predicts the development of low back pain and is a strong discriminator of those with and without low back pain. Performance may greatly depend on psychological factors, such as kinesiophobia, self-efficacy, and motivation. Virtual reality video games have been used in people with low back pain to encourage physical activity that would otherwise be avoided out of fear of pain or harm. Accordingly, we developed a virtual reality video game to assess the influence of immersive gaming on the Sørensen test performance.

OBJECTIVE

The objective of our study was to determine the physiological and psychological predictors of time to task failure (TTF) on a virtual reality Sørensen test in participants with and without a history of recurrent low back pain.

METHODS

We recruited 24 individuals with a history of recurrent low back pain and 24 sex-, age-, and body mass index-matched individuals without a history of low back pain. Participants completed a series of psychological measures, including the Center for Epidemiological Studies-Depression Scale, Pain Resilience Scale, Pain Catastrophizing Scale, Tampa Scale for Kinesiophobia, and a self-efficacy measure. The maximal isometric strength of trunk and hip extensors and TTF on a virtual reality Sørensen test were measured. Electromyography of the erector spinae, gluteus maximus, and biceps femoris was recorded during the strength and endurance trials.

RESULTS

A two-way analysis of variance revealed no significant difference in TTF between groups (P=.99), but there was a trend for longer TTF in females on the virtual reality Sørensen test (P=.06). Linear regression analyses were performed to determine predictors of TTF in each group. In healthy participants, the normalized median power frequency slope of erector spinae (beta=.450, P=.01), biceps femoris (beta=.400, P=.01), and trunk mass (beta=-.32, P=.02) predicted TTF. In participants with recurrent low back pain, trunk mass (beta=-.67, P<.001), Tampa Scale for Kinesiophobia (beta=-.43, P=.01), and self-efficacy (beta=.35, P=.03) predicted TTF.

CONCLUSIONS

Trunk mass appears to be a consistent predictor of performance. Kinesiophobia appears to negatively influence TTF for those with a history of recurrent low back pain, but does not influence healthy individuals. Self-efficacy is associated with better performance in individuals with a history of recurrent low back pain, whereas a less steep median power frequency slope of the trunk and hip extensors is associated with better performance in individuals without a history of low back pain.

The effect of age on fitness among female firefighters

Background

The physical demands of firefighting require both cardiovascular and muscular fitness, which both decline with age. While much has been published on age-related changes among male firefighters (FFs), data on female FFs are lacking.

Aims

To describe cardiorespiratory fitness (CRF) and muscular fitness in a sample of female career FFs ranging in age from 25 to 60 years and determine whether ageing affects their achievement of the current recommended professional CRF standards of 12 metabolic equivalents (METs).

Methods

Data were collected on female FFs over an 11-year period. A cross-sectional analysis using one-way analysis of variance with Bonferroni post hoc comparisons was used to compare age groups.

Results

There were 96 study participants. Maximum METs was significantly higher (P < 0.01) in the 25- to 34-year age group (14.6 ± 2.1) compared with the 35-44 age group (12.9 ± 2.0 METs) and the 45-54 age group (12.2 ± 1.8 METs, P < 0.001). While the mean values of all measured age groups met or exceeded the 12-MET profession standard, as many as one-third of FFs <45 years of age and 43% of FFs >45 years of age fell below the benchmark of 12 METs. Muscular fitness as measured by maximum number of push-ups, sit-ups and back endurance was not significantly different between age groups.

Conclusions

Fire departments should recognize and take steps to ensure all female FFs maintain CRF and muscular fitness throughout their careers.

Insertion and Presence of Fine-Wire Intramuscular Electrodes to the Lumbar Paraspinal Muscles Do Not Affect Muscle Performance and Activation During High-Exertion Spinal Extension Activities

BACKGROUND

Low back pain (LBP) is commonly associated with paraspinal muscle dysfunctions. A method to study deep lumbar paraspinal (ie, multifidus) muscle function and neuromuscular activation pattern is intramuscular electromyography (EMG). Previous studies have shown that the procedure does not significantly impact muscle function during activities involving low-level muscle contractions. However, it is currently unknown how muscular function and activation are affected during high-exertion contractions.

OBJECTIVE

To examine the effects of insertion and presence of fine-wire EMG electrodes in the lumbar multifidus on muscle strength, endurance, and activation profiles during high-exertion spinal extension muscle contractions.

DESIGN

Single-blinded, repeated measures intervention trial.

SETTING

University clinical research laboratory PARTICIPANTS: Twenty individuals between the ages of 18-40 free of recent and current back pain.

METHODS

Muscle performance was assessed during 3 conditions (with [WI] and without [WO] presence of intramuscular electrodes, and insertion followed by removal [IO]). Isometric spinal extension strength was assessed with a motorized dynamometer. Muscle endurance was assessed using the Sorensen test with neuromuscular activation profiles analyzed during the endurance test.

MAIN OUTCOME MEASUREMENTS

Spinal extensor muscle strength, endurance, and activation.

RESULTS

Our data showed no significant difference in isometric strength (P = .20) between the 3 conditions. A significant difference in muscle endurance was found (P = .03). Post hoc analysis showed that the muscle endurance in the IO condition was significantly higher than the WO condition (161.3 ± 58.3 versus 142.1 ± 48.2 seconds, P = .04), likely due to a learning effect. All 3 conditions elicited minimal pain (range 0-4/10) and comparable muscle activation profiles.

CONCLUSION

Our findings suggested the sonographically guided insertion and presence of fine-wire intramuscular EMG electrodes in the lumbar multifidus muscles had no significant impact on spinal extension muscle function. This study provides evidence that implementing intramuscular EMG does not affect muscle performance during high-exertion contractions in individuals with no current back pain.

LEVEL OF EVIDENCE

II.

Understanding Monitoring Technologies for Adults With Pain: Systematic Literature Review

BACKGROUND

Monitoring of patients may decrease treatment costs and improve quality of care. Pain is the most common health problem that people seek help for in hospitals. Therefore, monitoring patients with pain may have significant impact in improving treatment. Several studies have studied factors affecting pain; however, no previous study has reviewed the contextual information that a monitoring system may capture to characterize a patient's situation.

OBJECTIVE

The objective of this study was to conduct a systematic review to (1) determine what types of technologies have been used to monitor adults with pain, and (2) construct a model of the context information that may be used to implement apps and devices aimed at monitoring adults with pain.

METHODS

A literature search (2005-2015) was conducted in electronic databases pertaining to medical and computer science literature (PubMed, Science Direct, ACM Digital Library, and IEEE Xplore) using a defined search string. Article selection was done through a process of removing duplicates, analyzing title and abstract, and then reviewing the full text of the article.

RESULTS

In the final analysis, 87 articles were included and 53 of them (61%) used technologies to collect contextual information. A total of 49 types of context information were found and a five-dimension (activity, identity, wellness, environment, physiological) model of context information to monitor adults with pain was proposed, expanding on a previous model. Most technological interfaces for pain monitoring were wearable, possibly because they can be used in more realistic contexts. Few studies focused on older adults, creating a relevant avenue of research on how to create devices for users that may have impaired cognitive skills or low digital literacy.

CONCLUSIONS

The design of monitoring devices and interfaces for adults with pain must deal with the challenge of selecting relevant contextual information to understand the user's situation, and not overburdening or inconveniencing users with information requests. A model of contextual information may be used by researchers to choose possible contextual information that may be monitored during studies on adults with pain.

Muscle function and size in the lumbar spine before and after a four week exercise intervention

BACKGROUND

Exercise of the spinal muscles is recommended for a variety of rehabilitative reasons but it is not always clear whether interventions are effective in improving the performance of the muscles or whether their benefit is elicited via other mechanisms.

OBJECTIVE

To explore the effects of an exercise intervention on the size and exercise performance of the lumbar spine extensor muscles.

METHODS

Eleven healthy participants undertook a four week programme of exercise. Magnetic resonance imaging and phosphorus spectroscopy were performed before and after the intervention to determine the time to fatigue and phosphocreatine (PCr) depletion during a muscle endurance test (modified Biering-Sørensen) together with muscle cross-sectional area (CSA).

RESULTS

The post intervention measures were significantly different to the pre-intervention results for the time to fatigue (post-pre: 20.5 ± 22.7 s (P= 0.014)) and PCr depletion both at the point of fatigue (post-pre: 9.5 ± 11.9% (P= 0.024)) and at a matched time-point (post-pre: 12.2 ± 11.9% (P= 0.007)). CSA was not significantly different in any muscle.

CONCLUSIONS

Exercise improved the performance of the trunk muscles despite no impact on CSA. This demonstrated the importance of obtaining a wide range of measures when assessing the effectiveness of exercise intervention programmes.

Evaluating abdominal core muscle fatigue: Assessment of the validity and reliability of the prone bridging test

The aims of this study were to research the amplitude and median frequency characteristics of selected abdominal, back, and hip muscles of healthy subjects during a prone bridging endurance test, based on surface electromyography (sEMG), (a) to determine if the prone bridging test is a valid field test to measure abdominal muscle fatigue, and (b) to evaluate if the current method of administrating the prone bridging test is reliable. Thirty healthy subjects participated in this experiment. The sEMG activity of seven abdominal, back, and hip muscles was bilaterally measured. Normalized median frequencies were computed from the EMG power spectra. The prone bridging tests were repeated on separate days to evaluate inter and intratester reliability. Significant differences in normalized median frequency slope (NMF_slope ) values between several abdominal, back, and hip muscles could be demonstrated. Moderate-to-high correlation coefficients were shown between NMF_slope values and endurance time. Multiple backward linear regression revealed that the test endurance time could only be significantly predicted by the NMF_slope of the rectus abdominis. Statistical analysis showed excellent reliability (ICC=0.87-0.89). The findings of this study support the validity and reliability of the prone bridging test for evaluating abdominal muscle fatigue.

Low back pain characterized by muscle resistance and occupational factors associated with nursing

Objective

to identify the occupational factors associated with low back pain using a surveillance tool and to characterize the low back pain by the resistance of the extensor muscles of the vertebral column among nursing professionals at an Intensive Care Unit.

Methods

Cross-sectional study. The workers answered a questionnaire about occupational factors and participated in a resistance test of the extensor muscles of the vertebral column. Associations were established through Student's T-test or Mann-Whitney's U-test and correlations using Pearson's test.

Results

Out of 48 participants, 32 (67%) suffered from low pain. For the resistance test, the subjects suffering from low back pain endured less time in comparison with asymptomatic subjects, but without significant differences (p=0.147). The duration of the pain episode showed a significant negative correlation (p=0.016) with the results of the resistance test though. The main factors identified as causes of low back pain were biomechanical and postural elements, conditions of the muscle structure and physical and organizational conditions.

Conclusions

the main occupational factors associated with the low back pain were the posture and the characteristics of the physical and organizational conditions. In addition, the extensor muscles of the column showed a trend towards lesser resistance for workers in pain. This evidence is important when considering prevention and treatment strategies.

Performance based on sEMG activity is related to psychosocial components: differences between back and abdominal endurance tests

The influence of psychosocial components on back and abdominal endurance tests in patients with persistent non-specific low back pain should be investigated to ensure the correct interpretation of these measures. Three-hundred and thirty-two patients (291 men and 41 women) from 19 to 63years performed an abdominal and back muscle endurance test after completing some psychosocial questionnaires. During the endurance tests, surface electromyography signals of the internal obliques, the external obliques, the lumbar multifidus and the iliocostalis were recorded. Patients were dichotomized as underperformers and good performers, by comparing their real endurance time, to the expected time of endurance derived from the normalized median frequency slope. Independent t-tests were performed to examine the differences on the outcome of the questionnaires. In the back muscle endurance test, the underperformers had significantly lower (p<0.05) scores on some of the physical subscales of the SF-36. The underperformers group of the AE test scored significantly higher on the DRAM MZDI (p=0.018) and on the PCS scale (p=0.020) and showed also significantly lower scores on the SF-36 (p<0.05). Back muscle endurance tests are influenced by physical components, while abdominal endurance tests seem influenced by psychosocial components.

Ability to discriminate between healthy and low back pain sufferers using ultrasound during maximum lumbar extension

OBJECTIVE

To analyze the ability to discriminate between healthy individuals and individuals with chronic nonspecific low back pain (CNLBP) by measuring the relation between patient-reported outcomes and objective clinical outcome measures of the erector spinae (ES) muscles using an ultrasound during maximal isometric lumbar extension.

DESIGN

Cross-sectional study with screening and diagnostic tests with no blinded comparison.

SETTING

University laboratory.

PARTICIPANTS

Healthy individuals (n=33) and individuals with CNLBP (n=33).

INTERVENTIONS

Each subject performed an isometric lumbar extension. With the variables measured, a discriminate analysis was performed using a value ≥ 6 in the Roland and Morris disability questionnaire (RMDQ) as the grouping variable. Then, a logistic regression with the functional and architectural variables was performed. A new index was obtained from each subject value input in the discriminate multivariate analysis.

MAIN OUTCOME MEASURES

Morphologic muscle variables of the ES muscle were measured through ultrasound images. The reliability of the measures was calculated through intraclass correlation coefficients (ICCs). The relation between patient-reported outcomes and objective clinical outcome measures was analyzed using a discriminate function from standardized values of the variables and an analysis of the reliability of the ultrasound measurement.

RESULTS

The reliability tests show an ICC value >.95 for morphologic and functional variables. The independent variables included in the analysis explained 42% (P=.003) of the dependent variable variance.

CONCLUSIONS

The relation between objective variables (electromyography, thickness, pennation angle) and a subjective variable (RMDQ ≥ 6) and the capacity of this relation to identify CNLBP within a group of healthy subjects is moderate. These results should be considered by clinicians when treating this type of patient in clinical practice.

Effect of two different exercise regimens on trunk muscle morphometry and endurance in soldiers in training

BACKGROUND

Limited evidence exists on how strength and endurance exercises commonly used to prevent low back pain affect muscle morphometry and endurance.

OBJECTIVE

The purpose of this study was to analyze the effects of 2 exercise regimens on the morphometry and endurance of key trunk musculature in a healthy population.

DESIGN

The study was designed as a randomized controlled trial.

SETTING

The study was conducted in a military training setting.

PARTICIPANTS

A random subsample (n=340; 72% men, 28% women; mean [±SD] age=21.9±4.2 years; mean [±SD] body mass index=24.8±2.8 kg/m2) from the larger Prevention of Low Back Pain in the Military trial (N=4,325) was included.

INTERVENTION

The core stabilization exercise program (CSEP) included low-load/low-repetition motor control exercises, whereas the traditional exercise program (TEP) included exercises conducted at a fast pace, with the use of high-load, high-repetition trunk strengthening exercises.

MEASUREMENTS

Baseline and follow-up examinations included ultrasound imaging of the trunk muscles and endurance tests. Linear mixed models were fitted to study the group and time effect and their interactions, accounting for the clustering effect.

RESULTS

Symmetry generally improved in the rest and contracted states, but there were no differences suggestive of muscle hypertrophy or improved ability to contract the trunk muscles between soldiers receiving the CSEP or the TEP. Total trunk endurance time decreased over the 12-week period, but endurance performance favored soldiers in the CSEP group. Endurance time was not associated with future episodes of low back pain.

LIMITATIONS

The lack of morphological changes may not be detectable in an already-active cohort, or a more intensive dose was needed.

CONCLUSIONS

Although improved symmetry was noted, neither the CSEP nor the TEP resulted in muscle hypertrophy. Longer endurance times were noted in individuals who completed the CSEP but were not strongly predictive of future low back pain episodes.

Relationship between different measures of pain-related fear and physical capacity of the spine in patients with chronic low back pain

BACKGROUND CONTEXT

It has been controversially stated that pain-related fear is a more important determining factor for disability in chronic low back pain (CLBP) than pain or physical impairment in itself. So far, the relationship between psychological and physiological determinants of chronic pain, that is, pain-related fear and physiological abilities, remains unclear.

PURPOSE

To evaluate whether pain-related fear assessed by different tools (both task specific and non task specific) is related to physical capacity measured by specific spine tests and, secondarily, to explore the relationship between different pain-related fear assessment tools.

STUDY DESIGN/SETTING

Cross-sectional study.

PATIENT SAMPLE

Fifty patients with CLBP (50% women; meanage [standard deviationage]: 44.2 [9.5 years]).

OUTCOME MEASURES

Physical capacity by means of three specific spine tests, that is, the finger-floor distance test (flexibility), a maximal isometric strength test of trunk extensor muscles (strength), and the Sorensen test (endurance). Pain-related fear by means of self-report measures, that is, the Tampa Scale for Kinesiophobia (TSK), the Photograph Series of Daily Activities (PHODA), and a fear visual analog scale (FVAS) tailored to the spine tests.

METHODS

Participants were asked to complete the TSK and PHODA and to perform the three spine tests. Right before performing each of the spine tests, an FVAS was filled out. Linear regression analyses controlling for gender and age were performed to study the association between the pain-related fear measurements and the results of the spine tests. To investigate the relationship between the pain-related fear measurements, correlation tests were performed.

RESULTS

The linear regression analyses revealed that neither the TSK and PHODA scores nor the FVAS scores were significantly related to the physical capacity measurements. The correlational tests showed no significant correlation between the PHODA, TSK, and FVAS scores.

CONCLUSIONS

The present study shows that neither the task-specific tool (FVAS) nor the non task-specific questionnaires (TSK and PHODA) were significantly correlated to the spine tests in patients with CLBP. This is contrary to earlier evidence according to which physical capacity is inversely related to the level of pain-related fear, and it suggests that one should not draw conclusions about physical capacity based on pain-related fear scores. Furthermore, the different assessment tools for pain-related fear were surprisingly not correlated with each other.

Educational differences in estimated and measured physical fitness

BACKGROUND

Available information about the association between education and physical fitness (PF) is scarce. The purpose of this study was to examine educational differences in PF in the working age population using different methods to assess PF.

METHODS

The Health 2000 Survey was carried out for adults aged ≥ 30 years (n = 8028) in Finland. For this study, 30-54-year-old men and women with data on PF and physical activity (PA) were selected (n = 3724). PF was assessed by self-estimated overall physical fitness and running ability, a physician's estimation of a participant's working capacity, the trunk extensors' endurance and hand grip strength tests. The highest educational qualification taken by the participant was used as a measure of education. The analyses were adjusted for age, PA, BMI, smoking and chronic diseases.

RESULTS

PF was best in the high-educated men and women. The educational differences were minor in self-estimated overall PF. Adjusting for the covariates, the differences in self-estimated running ability and working capacity decreased. The educational differences in the trunk extensors' endurance test were independent of covariates. PA and other health behaviours contributed most to the differences.

CONCLUSION

People with high education had better PF irrespective of the method used to assess PF. A large amount of the educational differences could be explained by PA and other health behaviours. More research is needed to understand the determinants of educational differences in PF.