Low back pain development differentially influences centre of pressure regularity following prolonged standing

Effects of Corrective Exercises on Work-Related Musculoskeletal Disorders and Quality of Life in Surgical Residents: A Pilot, Quasi-Experimental Study

PURPOSE

Work-related musculoskeletal disorders (WMSDs) are one of the most important reasons for absenteeism, high costs of health care and human injuries; the latter are very common in medical staff. The present study was designed to evaluate the effects of corrective exercises on quality of life and work-related musculoskeletal disorders in surgical residents.

METHODS

In a quasi-experimental study with a one-group pretest-posttest design, we assessed the eligibility of 135 surgical assistants. All recruited participants performed corrective exercises and were followed for 12 months. The primary outcome of the study was any change in the surgical residents' work-related musculoskeletal disorders, which was assessed using the Nordic Musculoskeletal Questionnaire (NMQ) and the Numerical Pain Rating Scale (NPRS) prior to, and 3, 6, and 12 months after intervention. The secondary outcome was any change in the surgical residents' quality of life (QOL) score, which was assessed at baseline, 6 and 12 months after the intervention using the World Health Organization Quality of Life - BREF (WHOQOL-BREF) questionnaire.

RESULTS

One hundred eligible surgical residents were enrolled, of whom 67 (67%) completed the study. At baseline the majority of the participants were female and >30 years of age. Fifty-five percent of them used analgesic drugs. The use of analgesic drugs per week fell by 14.7% from baseline to 12 months; the change was statistically significant (p = 0.042). The effect of corrective exercises on the intensity of pain in the shoulder (p = 0.002), hand/wrist (p = 0.001), upper back (p = 0.03), lower back (p = 0.02) and knee (p = 0.01) was significant. Corrective exercises also led to a significant rise in the quality-of-life score (p < 0.019).

CONCLUSIONS

This study demonstrated the effectiveness of corrective exercises in reducing work-related musculoskeletal disorders and improving quality of life among surgical residents.

Distinctive characteristics of prolonged standing low back pain developers' and the associated risk factors: systematic review and meta-analysis

Pain developers (PDs) are considered a pre-clinical low back pain (LBP) population at risk of clinical LBP development and thus exacting great social and economic costs. Therefore, it is necessary to comprehensively investigate their distinctive characteristics and the risk factors of standing-induced LBP based on which appropriate preventive measures can be planned. Scopus, Web of Science, and PubMed databases as well as Google Scholar and ProQuest were systematically searched from inception through 14 July 2022 using a combination of terms relevant to 'standing' and 'LBP'. Studies with low risk of bias in English and Persian using a methodological quality scoring system were deemed eligible for inclusion if they were laboratory studies using prolonged standing duration greater than 42 min to classify adult PDs and non-pain developers (NPDs) without a history of LBP. PDs were compared with NPDs in demographics, biomechanical, and psychological outcomes. Weighted or standardized mean differences, and Hedge's g were generated to determine the pooled effect sizes using STATA software version 17. 52 papers and theses involving 1070 participants (528 PDs and 542 NPDs) were eligible for inclusion in the systematic review 33 of which were used in meta-analyses. Significant differences between PDs and NPDs in terms of movement patterns, muscular, postural, psychological, structural, and anthropometric variables were evidenced. The following factors were found to have a statistically significant association with standing-induced LBP: lumbar fidgets (Hedge's g - 0.72, 95% CI - 1.35 to - 0.08, P = 0.03), lumbar lordosis in participants over 25 years (Hedge's g 2.75, 95% CI 1.89-3.61, P < 0.001), AHAbd test (WMD 0.7, 95% CI 0.36-1.05, P < 0.001), GMed co-activation (Hedge's g 4.24, 95% CI 3.18-5.3, P < 0.001), and Pain Catastrophizing Scale (WMD 2.85, 95% CI 0.51-5.19, P = 0.02). Altered motor control displayed in AHAbd test and higher lumbar lordosis in individuals over 25 years seem to be probable risk factors for standing-induced LBP. In order to detect standing-induced LBP risk factors, future researchers should investigate the association of the reported distinctive characteristics to the standing-induced LBP and that whether they are manipulable through various interventions.

Movement Behavior and Health Outcomes among Sedentary Adults: A Cross-Sectional Study

BACKGROUND

Sedentary behavior, which is highly prevalent among office workers, is associated with multiple health disorders, including those of the musculoskeletal and cardiometabolic systems. Although prior studies looked at postures or physical activity during work or leisure time, few analyzed both posture and movement throughout the entire day.

OBJECTIVE

This cross-sectional pilot study examined the movement behavior of sedentary office workers during both work and leisure time to explore its association with musculoskeletal discomfort (MSD) and cardiometabolic health indicators.

METHODS

Twenty-six participants completed a survey and wore a thigh-based inertial measuring unit (IMU) to quantify the time spent in different postures, the number of transitions between postures, and the step count during work and leisure time. A heart rate monitor and ambulatory blood pressure cuff were worn to quantify cardiometabolic measures. The associations between movement behavior, MSD, and cardiometabolic health indicators were evaluated.

RESULTS

The number of transitions differed significantly between those with and without MSD. Correlations were found between MSD, time spent sitting, and posture transitions. Posture transitions had negative correlations with body mass index and heart rate.

CONCLUSIONS

Although no single behavior was highly correlated with health outcomes, these correlations suggest that a combination of increasing standing time, walking time, and the number of transitions between postures during both work and leisure time was associated with positive musculoskeletal and cardiometabolic health indicators among sedentary office workers and should be considered in future research.

Comparison of proprioceptive postural control strategies between prolonged standing induced low back pain developers and non-low back pain developers

BACKGROUND

Proprioception deficit has been suggested as a possible mechanism contributing for the impaired postural control in low back pain (LBP) patients. Whether proprioception deficit is a result of or a cause of LBP has not been investigated.

OBJECTIVE

The purpose of this study was to compare proprioceptive postural control strategies between prolonged standing induced low back pain developers (PDs) and non-pain developers (NPDs).

METHOD

Thirty-two healthy subjects performed 1-h prolonged standing and their ratings of perceived LBP have been recorded. Eight quiet standing trials for 60 s performed immediately before and after the prolonged standing. Postural control was challenged by muscle vibration and different postural conditions during quiet standing. Data were recorded using a force platform.

RESULTS

Forty percentage of participants is classified as PD. Before the prolonged standing, relative proprioceptive weighting was greater in the PD compared to NPD group (P = .029). Main effect of postural condition (F_1,24 = 5.21, P = .032) and interaction of time by group (F_1,24 = 8.08, P = .009) were significant for COP displacement in anteroposterior direction. Interaction of postural condition by group (F_1,26 = 7.82, P = .010) and time by group (F_1,26 = 9.71, P = .004) were significant for COP displacement in mediolateral direction. Main effect of postural condition (F_1,26 = 6.31, P = .018) and interaction of postural condition by group (F_1,26 = 7.07, P = .013) were significant for mean velocity in mediolateral direction.

CONCLUSION

The PD group has altered proprioceptive postural control strategies before and after prolonged standing. Proprioception deficit should not be considered to be solely an adaptive response and may be causal for LBP development.

Nonlinear analysis of postural changes related to the movement interventions during prolonged standing task

This study assessed the effects of movement-based interventions on the complexity of postural changes during prolonged standing. Twenty participants, equally distributed in gender and standing work experience (SWE), completed three simulated prolonged standing sessions: without movement (control), leg exercise and footrest. The amount and complexity of variability in the centre of pressure (COP) and lumbar curvature angle were quantified using linear and nonlinear tools. Lower leg swelling and back/leg discomfort were also monitored. Participants in the SWE group showed significantly greater postural complexity during the standing. Regular leg exercise resulted in significantly higher postural complexity and lower leg discomfort and swelling. The footrest led to significant changes in amount of COP variability. Both interventions significantly reduced back discomfort. Overall, the nonlinear analysis of postural changes provided different findings compared to linear ones, considering the standing time, interventions and standing job experience. Nonlinear results were consistent with leg discomfort and swelling. Practitioner summary: The effect of movement-based interventions on dynamics of postural alterations over prolonged standing were characterised using nonlinear techniques. The effect of standing work experience was also considered. Previous experience of standing jobs and leg movements increase the complexity of postural behaviour over standing period.

The Effect of Standing Mats on Biomechanical Characteristics of Lower Limbs and Perceived Exertion for Healthy Individuals during Prolonged Standing

Objective

To identify the effect of standing mats on biomechanical characteristics of lower limbs and perceived exertion for healthy adult individuals during a prolonged standing task.

Methods

32 healthy college students were recruited in the randomized and cross-over designed trial according to the effect size and statistical power. After collecting the anthropometric data, each participant was asked to finish 2 sessions of 4-hour prolonged standing tasks on standing mats (MS) and hard ground (GS) in a random order and with a 72-hour interval rest. The plantar pressure distribution, foot morphology, and scores of the BESS (balance error scoring system) would be recorded pre- and posteach task. The Borg Rating of Perceived Exertion (RPE) would be collected during the whole task. Paired-samples t test was adopted to analyse the before and after difference within group and independent-samples t test was adopted to analyse the difference between groups separately.

Results

(1) A prolonged standing task on both MS and GS have a negative effect on RPE and balance performance. (2) The negative effect on RPE and balance performance induced by MS is significantly smaller than that induced by GS. (3) Compared to GS, prolonged standing on MS has a lower peak plantar pressure and an implicit decrease in navicular drop and AHI (arch index).

Conclusion

Standing mat tends to alleviate the fatigue induced by prolonged standing in lower limbs, optimize the distribution of plantar pressure, and maintain the stability.

The effect of walking and stationary work on the acute back pain, muscle activation, posture and postural control of older women

Back pain is associated with activity such as walking or assembly line work that involves upper-body movement. However, no single study has explored the effect of these tasks on back pain, spinal angles and balance in an older adult female population. This study investigated changes in back pain, postural sway, upper-, lower- and full-spine angle and EMG activation of trunk muscles following 30 minutes of walking and a modified quiet standing task. Fourteen older adult females (62 ± 11yrs) with low to moderate chronic back pain were recruited as participants. Findings demonstrated that following these activities, increased acute back pain and upper-spine flexion occur although acute back pain was not clinically significant; postural control and muscle activation remained unchanged. This suggests that walking and modified quiet standing can lead to subtle acute back pain in older females that could be due to an increased upper spinal flexion rather than muscle fatigue. Practitioner summary: Back pain and postural problems are common in older adults. Older adult female participants experienced increased back pain and greater upper-spine flexion following 30-minute walking and standing with trunk rotation, but the practical importance was less clear. However, balance was unaffected, suggesting no increase in fall risk. Abbreviations: CBP: chronic back pain; MQS: modified quiet standing; QS: quiet standing; RPE: rating of perceived exertion; TD: trapezius descendens; TT: trapezius transversalis; TA: trapezius ascendens; ESL: erector spinae longissimus; C7: seventh cervical vertebrae; T7: seventh thoracic vertebrae; T10: tenth thoracic vertebrae; T12: twelfth thoracic vertebrae; L2: second lumbar vertebrae; S2: second sacral vertebrae; AP: anterior-posterior; ML: medial-lateral; SWAYtot: total postural sway; M: mean.

Determining the interactions between postural variability structure and discomfort development using nonlinear analysis techniques during prolonged standing work

PURPOSE

Nonlinear analysis techniques provide a powerful approach to explore dynamics of posture-related time-varying signals. The aim of this study was to investigate the fundamental interactions between postural variability structure and discomfort development during prolonged standing.

METHODS

Twenty participants, with equal distribution for gender and standing work experience (SWE), completed a simulated long-term standing test. Low back and legs discomfort, center of pressure, lumbar curvature, and EMG activity of trunk and leg muscles were monitored. Nonlinear measures including largest lyapunov exponent, multi-scale entropy, and detrended fluctuation analysis were applied to characterize the variability structure (i.e., complexity) in each signal. The size (i.e., amount) of variability was also computed using traditional linear metrics.

RESULTS

With progress of low back and legs discomfort over standing periods, significant lower levels were perceived by the participants having SWE. The amount of variability in all signals (except external oblique EMG activity) were significantly increased with the time progress for all participants. The structure of variability in most signals demonstrated a lower complexity (more regularity) with fractal properties that deviated from 1/f noise. The SWE group showed a higher complexity levels.

CONCLUSIONS

Overall, the findings verified variations in structure and amount of the postural variability. However, nonlinear analysis identified postural strategies according to the perceived discomfort in a different way. These results provide supports for future application of nonlinear tools in evaluating standing tasks and related ergonomics interventions as it allows further insight into how discomfort development impact the structure of postural changes.

A comparison of functional movement patterns between female low back pain developers and non-pain developers

BACKGROUND

Distinctive features of low back pain-developers (LBPDs) as pre-clinical low back pain (LBP) population have been evidenced in three areas of alignment, muscle activation, and movement patterns. To clarify whether the reported altered functional movement patterns in chronic LBP patients result from or result in LBP disorders, LBPDs' functional movement patterns should be investigated.

OBJECTIVES

This study aimed to compare female LBPDs' functional movement patterns with non-pain developers' (NPDs).

METHODS

Sixty female LBPDs and NPDs were recruited based on the research requirements. The Functional Movement Screen (FMS) was used to investigate movement quality. Data were compared between groups via Mann-Whitney U tests and correlation analyses examined association between pain intensity and onset during prolonged standing and the FMS score. Receiver Operating Characteristic Curves and Chi Squares were conducted to find the best cutoff points. An alpha level of p≤0.05 was used to establish statistical significance.

RESULTS

LBPDs scored significantly lower, or rather worse than NPDs in the FMS composite score (12.06±1.33 vs. 16.43±1.59, U = 3, P < 0.001). Moreover, the optimal cutoff scores of≤14 on the FMS, 2 on the push-up, and 1 on the deep squat discriminated between female LBPDs and NPDs. The FMS composite score was correlated negatively with LBP intensity (r (60) = -0.724, p < 0.001) and positively with LBP onset (r (60) = 0.277, p = 0.032) during prolonged standing. Finally, the results indicated that female LBPDs presented with at least one bilateral asymmetry on the FMS had 10 times (95% CI, 2.941-34.008) and with at least two bilateral asymmetries on the FMS had 15.5 times (95% CI, 3.814-63.359) higher odds of developing LBP during prolonged standing than NPDs.

CONCLUSIONS

Female LBPDs, who are at higher risk for developing LBP in the future, have significantly lower quality of functional movement patterns compared to NPDs. Moreover, the FMS appears to show promise for predicting individuals who are at risk for LBP development during prolonged standing.

Increasing standing tolerance in office workers with standing-induced back pain

Sit-stand desks are popular however many people have standing-induced low back pain (LBP). People with LBP have fewer standing weight shifts compared with back-healthy people. Participants were classified as standing-tolerant or intolerant. Participants were provided sit-stand desks for 12 weeks. Participants were assigned to intervention (graded standing exposure and exercise) or control (no instruction) conditions. Participants reported weekly sitting time and average/worst LBP. Standing weight shifts and LBP were re-assessed post-intervention. All groups decreased sitting time (range: 30-50%) over 12 weeks. Sitting time and average LBP were correlated in all standing-intolerant individuals, worst LBP and sitting time were correlated for intervention group only. All standing-intolerant individuals increased standing weight shifts and decreased LBP after 12-weeks. Standing-intolerant individuals benefitted from 12-weeks of sit-stand desk use regardless of intervention. Motivated individuals with standing-induced LBP may increase standing tolerance with sit-stand desk use. Additional benefits may exist when structured guidance is provided. Practitioner summary: Many people are standing-intolerant due to low back pain (LBP). This lab and field-based study showed some benefits from structured approaches to gradually progress standing time when transitioning to standing work. Using a sit-stand desk for 12 weeks resulted in decreased LBP and sitting time in standing-intolerant people. Abbreviations: LBP: low back pain; OSPAQ: Occupational Sitting and Physical Activity Questionnaire; VAS: visual analog scale; GRF: ground reaction force; WeekVASMAX: worst low back pain reported on visual analog scale for prior week; WeekVASAVE: average low back pain reported on visual analog scale for prior week; ICC: intraclass correlation coefficient; LabVASMAX: worst low back pain reported on visual analog scale during lab-based standing; LabVASAVE: average low back pain reported on visual analog scale during lab-based standing; FvR,L: vertical ground reaction force for right and left force plate; BWSSMALL: small (10-29% body weight) body weight shift; BWSLARGE: large (> 30% body weight) body weight shift; ActivPALSED: ActivePAL data for sedentary time; ActivPALSTND: ActivePAL data for standing time; ANOVA: analysis of variance; Standing Intolerant-INT: standing intolerant participants assigned to intervention condition; Standing Intolerant-CON: standing intolerant participants assigned to control condition; Standing Tolerant-INT: standing tolerant participants assigned to intervention condition; Standing Tolerant-CON: standing tolerant participants assigned to control condition; SI: standing intolerant; ST: standing tolerant; INT: intervention; CON: control.

Postural control is altered in females with excessive medial knee displacement

Knee valgus motion observed during landing tasks has been proposed as a predictor of future knee injury. It mainly involves excess motion in the frontal plane and is known to be greater in individuals with excessive medial knee displacement (MKD). This affects postural control during sports manoeuvres. Previous sports medicine-related research suggests that the nature of these fluctuations provide rich and more sensitive information to identify risk of (re)injury. We aimed to investigate the fluctuations of the centre of pressure (CoP) in individuals with and without excessive MKD. Twenty females (12 controls; 8 excessive MKD) were instructed to perform single-leg landing tasks from three different directions. The participants landed on a force plate and stayed still for 20 seconds. The fluctuations of the anterior-posterior and medial-lateral directions of the CoP were determined through the calculation of Sample Entropy. Mixed-model ANOVAs (3 [Landing Direction] x 2 [Group]) were used. We have found that only the entropy of the medial-lateral direction was different between groups. Individuals with excessive MKD exhibited an increase in entropy values, indicating greater randomness in CoP fluctuations. This suggests a decreased ability to adapt to environmental demands that likely result in an increased risk of injury.

Experimental knee-related pain enhances attentional interference on postural control

PURPOSE

To quantify how postural stability is modified during experimental pain while performing different cognitively demanding tasks.

METHODS

Sixteen healthy young adults participated in the experiment. Pain was induced by intramuscular injection of hypertonic saline solution (1 mL, 6%) in both vastus medialis and vastus lateralis muscles (0.9% isotonic saline was used as control). The participants stood barefoot in tandem position for 1 min on a force plate. Center of pressure (CoP) was recorded before and immediately after injections, while performing two cognitive tasks: (i) counting forwards by adding one; (ii) counting backwards by subtracting three. CoP variables-total area of displacement, velocity in anterior-posterior (AP-velocity) and medial-lateral (ML-velocity) directions, and CoP sample entropy in anterior-posterior and medial-lateral directions were displayed as the difference between the values obtained after and before each injection and compared between tasks and injections.

RESULTS

CoP total area ( - 84.5 ± 145.5 vs. 28.9 ± 78.5 cm²) and ML-velocity ( - 1.71 ± 2.61 vs. 0.98 ± 1.93 cm/s) decreased after the painful injection vs. Control injection while counting forward (P < 0.05). CoP total area (12.8 ± 53.9 vs. - 84.5 ± 145.5 cm²), ML-velocity ( - 0.34 ± 1.92 vs. - 1.71 ± 2.61 cm/s) and AP-velocity (1.07 ± 2.35 vs. - 0.39 ± 1.82 cm/s) increased while counting backwards vs. forwards after the painful injection (P < 0.05).

CONCLUSION

Pain interfered with postural stability according to the type of cognitive task performed, suggesting that pain may occupy cognitive resources, potentially resulting in poorer balance performance.

Occupational Characteristics of Low Back Pain Among Standing Workers in a Japanese Manufacturing Company

Low back pain (LBP) is a major public health problem that adversely affects the quality of life (QOL) of workers. The etiology of LBP is considered to be multi-factorial with individual, physical, and psychosocial factors contributing to its development and persistence. Although prevention of LBP in workers in the workplace is very important, only a small number of studies have assessed the risk factors and epidemiology of LBP among Japanese factory workers who stand as part of their job. This cross-sectional study investigated the prevalence of LBP in 691 factory employees who conducted their work while standing. Health-related QOL was evaluated using the Roland-Morris Disability Questionnaire (RDQ) to quantify the severity of LBP with the aim of identifying risk factors for LBP among workers who stand as part of their work in an electronics manufacturing company. We observed that the prevalence of LBP lasting for at least 48 hours within a week was 20.0% among participants, with female employees and those with a prior history of LBP having a significantly increased risk of developing LBP. The distribution of the RDQ score showed a negative regression curve among the employees, which was different from the normal distribution pattern reported previously in Japanese patients with LBP. These findings suggest that prolonged standing among factory workers poses an increased risk for LBP.