Walking breaks can reduce prolonged standing induced low back pain

The impact of different standing positions on gluteus medius activation and lumbar lordosis in LBP-developers during prolonged standing

Low back pain (LBP) development has been associated with increased hip muscle co-activation and lumbar lordosis during standing in previously asymptomatic individuals. It is commonly advised to use footrests to relieve LBP. The impact of adjusting arm position on lumbar biomechanics can also be impressive. This study aimed to compare the effects of normalized footrest height and changing arm position on Gluteus medius (GMed) muscle activity, lumbar lordosis, and pain intensity. Twenty-four female pain developers (PDs) were recruited, identified by a > 10 mm increase on the visual analog scale (VAS) during prolonged standing. Electromyography (EMG) recorded GMed activity, and photogrammetry measured lumbar lordosis at time points over one hour-standing. The first group (A) used the footrest intermittently, while the second group (B) additionally changed their arm positions. These variables were analyzed using repeated measures (between/within) ANOVA. No significant interaction was observed between the groups in right and left GMed co-contraction index (CCI) (p =  0.14). However, both groups exhibited a significant decrease in CCI during prolonged standing (time *  condition: p =  0.003). Additionally, Group B consistently demonstrated lower overall levels of co-contraction across time (p =  0.01). An approximate 6-degree reduction in lumbar lordosis was observed after prolonged standing with both interventions (group A and group B; p =  0.008 and p =  0.01, respectively), although no significant differences in lumbar lordosis were detected between the groups. Lumbar discomfort increased over time; however, the interventions significantly alleviated this discomfort after the intervention time point. Notably, group B reported lower pain intensity compared to group A (p =  0.007). Applying these interventions in the workplace could be beneficial to reduce discomfort for individuals who stand for long periods of time. Further research is needed to optimize these strategies and assess long-term benefits.

Lateral Pelvis and Lumbar Motion in Seated and Standing Office Work and Their Association With Transient Low Back Pain

OBJECTIVE

To assess frontal plane motion of the pelvis and lumbar spine during 2 h of seated and standing office work and evaluate associations with transient low back pain.

BACKGROUND

Although bending and twisting motions are cited as risk factors for low back injuries in occupational tasks, few studies have assessed frontal plane motion during sedentary exposures.

METHODS

Twenty-one participants completed 2 h of seated and standing office work while pelvic obliquity, lumbar lateral bending angles, and ratings of perceived low back pain were recorded. Mean absolute angles were compared across 15-min blocks, amplitude probability distribution functions were calculated, and associations between lateral postures and low back pain were evaluated.

RESULTS

Mean pelvic obliquity (sit = 4.0 ± 2.8°, stand = 3.5 ± 1.7°) and lumbar lateral bending (sit = 4.5 ± 2.5°, stand = 4.1 ± 1.6°) were consistently asymmetrical. Pelvic obliquity range of motion was 4.7° larger in standing (13.6 ± 7.5°) than sitting (8.9 ± 8.7°). In sitting, 52% (pelvis) and 71% (lumbar) of participants, and in standing, 71% (pelvis and lumbar) of participants, were considered asymmetric for >90% of the protocol. Lateral postures displayed weak to low correlations with peak low back pain (R ≤ 0.388).

CONCLUSION

The majority of participants displayed lateral asymmetries for the pelvis and lumbar spine within 5° of their upright standing posture.

APPLICATION

In short-term sedentary exposures, associations between lateral postures and pain indicated that as the range in lateral postures increases there may be an increased possibility of pain.

The role of diurnal variation in development of musculoskeletal pain during prolonged standing

BACKGROUND

Research suggests mechanical changes occur to the body over the course of the day including shrinking of the intervertebral disc height which can increase rotational stiffness and rigidity of the spinal column. Further, pain sensitivity has been observed to fluctuate throughout the day, suggesting variations in pain sensitivity. Previous work has identified biomechanical and neuromuscular features related to the development of musculoskeletal pain during prolonged standing; however, many protocols have not controlled for time of day.

RESEARCH QUESTION

Does the time of day (i.e., diurnal variation) have an effect on the common neuromuscular and biomechanical variables characterizing the development of standing musculoskeletal pain in a two-hour prolonged standing protocol?

METHODS

A convenience sample of 20 healthy young adults (10 female and 10 male) completed two 2-hour prolonged standing bouts (8:00 a.m. and 8:00 p.m.) on separate days. Visual analogue scales were used to measure pain perception of the low back, legs, and feet throughout each protocol. Neuromuscular control was measured using surface EMG on muscles of the trunk and lower extremities. Postural sway was captured using measures of joint range of motion, and the analysis of center of pressure trajectory data using a force plate.

RESULTS

Diurnal variation was observed to influence the development of musculoskeletal pain. Specifically, pain perception was found to be increased in the evenings as more participants were classified as pain developers in the PM sessions, and mean leg and foot pain perceptions were higher in the evening. Reduced postural sway patterns, and elevated co-contraction indices were found to be associated with the development of pain.

SIGNIFICANCE

These results suggest that future research assessing standing-pain protocols should control for time of day. Additionally, further research is warranted to explore the mechanistic causes of the development of standing pain.

The impact of breaking up sitting during simulated nightshifts on musculoskeletal pain: A randomised controlled trial

OBJECTIVES

Prolonged sitting is associated with an increased risk of musculoskeletal pain, especially in nightshift workers. However, research investigating effects of breaking up sitting on musculoskeletal pain during nightshifts is lacking. This study evaluated effects of prolonged sitting or breaking up sitting with short bouts of light-intensity physical activity on pain in healthy adults during simulated nightshifts.

METHODS

An in-laboratory randomised controlled trial was undertaken with 52 healthy adults completing five simulated nightshifts. Participants were randomised to prolonged sitting (Sit9; n = 26) or breaking up prolonged sitting (Break9; n = 26). Break9 group completed 3-min walking every 30 min during nightshifts, while Sit9 group remained seated. Musculoskeletal pain intensity and sensory/affective pain experiences were assessed. Linear mixed models examined pain within nights (pre-to post-shift) and across nights (pre-shift-night-1 to pre-shift-night-5).

RESULTS

Musculoskeletal pain intensity increased within nights for both Sit9 (mean change [95%CI] points: 0.14 [0.05, 0.24]) and Break9 (0.09 [0.001, 0.19], but not across nights (Sit9: -0.13 [-0.33, 0.08]; Break9: 0.07 [-0.14, 0.29]). Sensory-pain experience improved across nights for Sit9 (-3.08 [-4.72, -1.45]), but not within nights (0.77 [-0.004, 1.55]). There was no change in affective-pain experience in either group. Between-group difference was observed favouring Sit9 for improving sensory-pain across nights (β: 3.71 [1.42, 5.99]). No other between-group difference was observed.

CONCLUSION

Both prolonged sitting and breaking up sitting were associated with a within-night increase in musculoskeletal pain intensity. Compared to prolonged sitting, breaking up sitting did not induce benefits on pain in healthy adults working simulated nightshifts.

TRIAL REGISTRATION

ACTRN12619001516178.

An Assessment of Back and Shoulder Postures in Single-Handed Exertions: Expanding Ergonomic Reaching Guidelines to Consider Lumbar Spine Axial Twist

Occupational applicationsAcross a series of standing single-handed exertions performed at different lateral angles, distances, heights, and loads, lumbar axial twist exceeded an angular threshold of 9° in select exertions. Specifically, 9° of rightward axial twist was exceeded for all exertions performed laterally (90° from the body midline). Additionally, for those at the body midline, 9° of leftward axial twist was exceeded for upward exertions and exertions performed at far distances (tertiary reach envelope). Further, the data supports that for many exertions, lumbar flexion-extension and shoulder elevation would be unlikely to increase the potential for injury as angles remained within the in vivo lumbar neutral zone and were not considered overhead. Given the relationship between lateral hand exertions and lumbar axial twist, it is generally recommended that standing single-handed exertions not be performed beyond 60° from the midline. In addition to the current recommendations related to reach distance, future ergonomic reach envelope guidelines could benefit from incorporating recommendations on reach angle from the body midline.

Health-Related Benefits and Adherence for Multiple Short Bouts of Aerobic Physical Activity Among Adults

Most adults do not adhere to established aerobic physical activity (PA) guidelines due in part to various barriers. PA snacks, or periodic short bouts of activity (<10 minutes) offer a potential strategy to overcoming such barriers and increasing PA. Previous efforts have been focused on eliciting the health benefits of PA and exercise snacks, yet adherence to this concept has not been examined. The purpose of this review is to summarize the current literature assessing adherence to PA snacks and health-related outcomes associated with PA snacks. PubMed, CINAHL, and SPORTDiscus were searched for literature published between January 2018-September 2023. Studies investigating adherence and/or the health-related outcomes of PA snacks were included. Of 4201 articles identified, 12 studies were included in the review. Most of the studies were randomized (n = 10), focused on adults with a chronic disease/life-long condition or exhibited a sedentary lifestyle (n = 8), and reported positive health outcomes (n = 12; e.g., improvements in cardiometabolic markers and body composition). Five studies reported adherence to supervised and unsupervised PA snack interventions, with high rates ≥92%. This review supports and extends the previously reported health-related benefits of PA snacks. It also shows promise for increasing overall PA and adherence to the PA guidelines.

The Role of Back Muscle Dysfunctions in Chronic Low Back Pain: State-of-the-Art and Clinical Implications

Changes in back muscle function and structure are highly prevalent in patients with chronic low back pain (CLBP). Since large heterogeneity in clinical presentation and back muscle dysfunctions exists within this population, the potential role of back muscle dysfunctions in the persistence of low back pain differs between individuals. Consequently, interventions should be tailored to the individual patient and be based on a thorough clinical examination taking into account the multidimensional nature of CLBP. Considering the complexity of this process, we will provide a state-of-the-art update on back muscle dysfunctions in patients with CLBP and their implications for treatment. To this end, we will first give an overview of (1) dysfunctions in back muscle structure and function, (2) the potential of exercise therapy to address these dysfunctions, and (3) the relationship between changes in back muscle dysfunctions and clinical parameters. In a second part, we will describe a framework for an individualised approach for back muscle training in patients with CLBP.

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.

Does a break from sitting change biomechanical outcome measures or transient pain? A laboratory-based experimental study

BACKGROUND

Sitting can induce transient low back pain (LBP) in healthy individuals. A rest from sitting should provide relief, however, the parameters of breaks (activity type, intensity, duration, and timing) are not currently known.

OBJECTIVE

The purpose of this study was to examine the effect of 2-minute walking breaks at 40-minute intervals on sitting-induced LBP.

METHODS

Thirty-two healthy participants were recruited for a within-control study: two randomly presented sessions of sitting for 2 hours with and without breaks. Outcome measures were compared between condition and pain group using a three-way ANOVA with significance atp > 0.05.

RESULTS

Walking breaks at 40-minute intervals result in significantly lower pain ratings than those taken immediately before the break for sitting-induced back pain developers. However, this relief is short lived (<10 minutes), with ratings increasing to pre-break levels once the sitting exposure resumes. There were no differences in biomechanical factors between sessions. Regardless of session type, pain developers displayed higher spine fidget frequency than non-pain developers, females sat with less spine flexion, with greater gluteal activation levels, and with their center of pressure approximately half a centimeter to the left and forward compared to males, and males had significantly greater peak pressures over a smaller area compared to females.

CONCLUSION

Walking breaks at 40-minute intervals provide significant, but temporary, relief of sitting-induced back pain for pain developers. Future work should optimize break parameters and examine the longer-term benefit of breaks, especially for individuals that are not able to tolerate sitting for extended durations.

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.

Use of an inflatable mat to reduce body discomfort development when performing computer work at a standing desk

This study aimed to determine the effects of inflatable mat design on body discomfort, task performance, and musculoskeletal exposures during standing computer work. Twenty-seven healthy adults completed three 2-hour standing trials on different mediums (concrete floor, foam mat, and inflatable mat) on different days in an experimental laboratory. Both mats were associated with reduced discomfort in all lower-body regions and increased typing performance compared to the concrete floor. Perceived discomfort in lower extremities (except thighs) was further alleviated while standing on the inflatable mat than on the foam mat. Use of the inflatable mat led to increased lower-body muscle activity, a flexed lower back, and a wide range of sagittal knee movements. As standing time increased, body discomfort increased, typing accuracy decreased, and there were increased variations in muscle activity and postural movements in the lower body. The inflatable mat shows potential to improve the ergonomic experience during prolonged standing. Practitioner summary: Incorporating standing postures in office-based workplaces can reduce sitting time and may mitigate the health hazards associated with sedentary behaviour. With adequate weight-shifting movements, using an inflatable mat for standing could be an effective way to lessen discomfort and accumulated musculoskeletal strain due to constrained standing, without jeopardising task productivity. Abbreviations: APDF: amplitude probability distribution function. AVR: average rectified value. CI: confidence interval. CMRR: common mode rejection ratio. COP: center of pressure. CV: coefficient of variation. EA: electrical activity. EMG: electromyography. FL: fibularis longus. GM: gluteus medius. LBP: lower back pain. LES: lumbar erector spinae. MVC: maximum voluntary contraction. PD: pain developer. rANOVA: repeated-measures analysis of variance. SOL: soleus. VAS: visual analog scale. WPM: words per minute.

Enhancing the differentiation of walking and standing via the ratio of plantar pressures

Differentiation of standing and walking based on plantar pressures is helpful in developing strategies to reduce health risks in the workplace. In order to improve the differentiation ability, the paper proposes a new metric for posture differentiation, that is, the pressure ratio on the two anatomical plantar regions. The plantar pressures were collected from 30 persons during walking and standing. After verifying the normal distribution of the pressure ratio by the Monte Carlo method, two-way repeated-measures ANOVA was conducted for the pressure ratios. The advantage of the pressure ratio over two conventional pressure metrics (the average pressure and the peak pressure) is demonstrated by its much larger size effect. Furthermore, the pressure ratio permits to establish value ranges corresponding to walking and standing, which are less influenced by specific person factors, thus facilitating the design of a standardized posture recognition system. The underlying mechanism underlying the pressure ratio is discussed from the aspect of biomechanics of movement.

Office-workers maintain decreased workplace sitting time long-term following participation in a sit-stand desk intervention study

Previous studies report decreased workplace sitting time when standing desk interventions are provided to office workers. It is unclear whether decreased sedentary behaviours are maintained long-term. This was a follow-up to a previous intervention study to investigate whether observed sitting time decreases of 30-50% were sustained 12-24 months later. A secondary aim was to compare overall physical activity between office workers with and without standing desks. Although sitting time increased over the follow-up period, this did not reach significance and reductions in workplace sitting remained significantly lower (23.5% decrease) from baseline values. There were no differences in the physical activity measures between workers with and without access to standing desks, although this was a small sample size and further research is needed. Individuals who are motivated to try standing desks at work can benefit through decreased sitting time long-term, however this may not extend to increased overall physical activity levels. Practitioner summary: Providing standing desk options to office-based employees can have long-lasting impacts with reducing sitting time at work. Office workers who choose to stand at work do not appear to compensate with overall activity level reduction outside of work.Abbreviations: LBP: low back pain; OSPAQ: occupational sitting and physical activity questionnaire; VAS: visual analog scale; ANOVA: analysis of variance; BMI: body mass index; ICC: intraclass correlation coefficient.

Pain symptoms are reported earlier than quantitative measures of low back pain during prolonged standing

BACKGROUND

Along with quantitative measures, pain symptoms may help inform early interventions to prevent prolonged standing induced low back pain (LBP); however, the relationship between quantitative and qualitative measures has not been assessed.

OBJECTIVE

Determine the relationship between qualitative and quantitative measures of pain development during prolonged standing induced LBP development.

METHODS

Thirty-five participants performed two-hours of standing. A visual analog scale (VAS) and the Short-Form McGill Pain Questionnaire were used to assess the participant's LBP every 7.5-minutes. Participants were classified as a pain developer (PD) based on VAS scores or three consecutive pain symptom reports.

RESULTS

Pain symptom reports occurred 31.3 (±24.8) minutes earlier than the VAS reports. Eight participants (44%) were non-PDs with the VAS and PDs with the symptom method (p = 0.0047).

CONCLUSIONS

A subset of participants who were not categorized as LBP developers during prolonged standing using the VAS method still report LBP symptoms. The inclusion of pain symptom reporting could provide additional information for practitioners when identifying individuals who would benefit from early interventions for standing induced LBP.

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.