Morning/Evening differences in somatosensory inputs for postural control

Time of day and athlete status effects on the modified clinical test of sensory integration and balance (mCTSIB) and stability evaluation test (SET)

BACKGROUND

Concussions or musculoskeletal injuries may impair postural control, which is one diagnostic to help determine return-to-activity decisions. Postural control may be affected by diurnal rhythm.

RESEARCH QUESTION

Does time of day influence postural control as measured by two Neurocom Balance Master diagnostic protocols, the Modified Clinical Test of Sensory Interaction on Balance (mCTSIB) and the Stability Evaluation Test (SET)?

METHODS

Following Institutional Review Board (IRB) approval, consented participants completed the SET and mCTSIB twice: between 0700 and 1000; and between 1600 and 1900. We randomized and balanced testing order. Familiarization trials were completed for the mCTSIB and SET. Assessments were completed in a controlled laboratory environment. We instructed participants to get a normal night's sleep prior to testing and refrain from caffeine use and exhaustive exercise on the day of testing. Sixty-nine participants (48 female, 21 male: age = 21.42±2.56 years, height = 168.20±7.53 cm, mass = 72.05±16.60 kg) completed the study. Thirty-one of the participants were National Association of Intercollegiate Athletes (NAIA) student-athletes from the sports of baseball, soccer and softball. Average postural sway velocity was measured and compared by time of day for each of the balance conditions in the mCTSIB and SET protocols.

RESULTS

According to repeated measures ANOVA, there were no significant postural sway velocity main effects by time of day for any of the balance conditions. We found significant postural sway main effects by foam, stance and eyes. We also noted significant ANOVA between participants' differences for athlete status, but not for sex.

SIGNIFICANCE

These results inform practitioners about the importance of controlling time-of-day between baseline and post-injury testing, which may allow for more flexible, accurate and reliable diagnosis and return-to-activity decisions. Athletes displayed better static postural control, possibly warranting different normative values for diagnostic comparison.

The effect of time-of-day and sleep deprivation on postural control: A systematic review

BACKGROUND

Postural control (PC) can be affected by circadian rhythm and sleep deprivation, whereby it has been reported the result of PC measurement in clinical and experimental situations can be influenced by both factors. It has been suggested sleepiness can result in deficiency in PC, which in turn can lead to occupational accidents and subsequent injuries. This is while no study critically reviews or summarizes findings surrounding this topic in the literature.

RESEARCH QUESTION

Is there any significant effect of sleep deprivation and circadian rhythm on PC variables among healthy individuals?

METHODS

PubMed, Web of Science, Scopus, and Embase were used to detect relevant studies. Only studies that examined the effect of time of day and/or sleep loss on PC among healthy individuals were included in this systematic review.

RESULTS

Forty-nine studies were included based on the inclusion criteria. Both circadian rhythm and sleep loss had a significant effect on PC, whereas there are inconsistent findings for optimal postural control regarding time of day. In terms of sleep deprivation, all investigations indicated that sleep loss deteriorates PC.

SIGNIFICANCE

The current systematic review represents a significant effect of circadian rhythm and sleep deprivation on PC, whereby it is suggested that clinicians and researchers consider these factors when measuring PC since it may affect the result of research and clinical test. Moreover, PC may be worsened through sleeplessness; however, some studies revealed there is no linear relationship between time of wakefulness and deteriorating PC due to the influence of circadian rhythm. Hence, while PC, as an objective tool, can help to detect those who are sleep deprived, which in turn can lead to prevent possible musculoskeletal injuries, further studies are needed to reveal more understanding about the effect of sleep loss and circadian rhythm on PC.

Time-of-day effects on the postural control and symptoms in women with rheumatoid arthritis

The present study was designed to assess time-of-day effects on postural balance and symptoms of rheumatoid arthritis (RA) patients. A total of 15 American College of Rheumatology functional class I and II RA patients and 15 healthy controls aged between 45 and 55 (mean age: 50 ± 3) years of age voluntarily participated. We conducted a case-control, repeated-measures in design study. Postural balance, axillary temperature, pain intensity, fatigue, and sleepiness were measured during five test sessions at 06:00, 10:00, 14:00, 18:00, and 22:00 h. Participants were randomized to the order of test sessions, and each session was separated by >36 hours to minimize/eliminate learning effects. Center of pressure area (CoP_area) (p < .001), pain (p < .01), and sleepiness (p < .05) values were significantly higher at 06:00 and 22:00 h compared to 10:00, 14:00, and 18:00 h in the RA group. Fatigue significantly increased (p < .05) at 22:00 h in comparison to 10:00, 14:00, and 18:00 h in the RA group. Axillary temperature was significantly (p < .001) lower at 06:00 and at 22:00 h compared to 10:00, 14:00, and 18:00 h in the RA group. In the control group, there were no significant time-of-day difference in fatigue, but axillary temperature was significantly lower (p < .01) at 06:00 h compared to 10:00 h, 14:00, 18:00, and 22:00 h, sleepiness values were significantly higher (p < .05) at 06:00 and 22:00 h compared to 10:00, 14:00, and 18:00 h, and revealed CoP_area values were significantly (p < .05) higher at 06:00 h compared to 14:00 h. Finally, in the RA group, significant correlations were found between values of CoP_area and pain (r = 0.47; p < .001), sleepiness (r = 0.39; p < .01), fatigue (r = -0.46; p < .001), and also axillary temperature (r = -0.35; p < .001). Multiple linear regression analysis further indicated that in the RA group, time-of-day variation in postural balance was predicted collectively by that in pain and fatigue (30.7%) (R2 = 0.307; F = 11.53; p < .001). Our results first suggest that time-of-day significantly affects postural balance, axillary temperature, pain intensity, fatigue, and sleepiness in RA patients and second that the temporal variation observed in pain, fatigue, and somnolence are concomitant with that observed in postural balance.Abbreviations: RA: Rheumatoid arthritis; H&O questionnaire: Horne and Ostberg questionnaire; PSQI: Pittsburgh sleep quality index; HAQ: Health assessment questionnaire; SF-36: the short form-36; WOMAC: Western Ontario and McMaster Universities Osteoarthritis Index; CoP: The Center of foot Pressure; CoP_area: The Center of foot Pressure area; VAS: The Visual Analogue Scale; KSS: Karolinska Sleepiness Scale.

Initiation gait variability is higher in the morning in elderly inpatients

OBJECTIVE

Although elderly inpatients are known to experience decreased physical activity in the morning, falls occur frequently during this time. Gait variability is an evaluation of gait instability and a risk factor for falls. Gait initiation requires complex processes, and it is important to evaluate gait variability not only during steady-state gait but also during gait initiation. However, the effect of the diurnal pattern on variability in gait characteristics is still unknown. The aim of this study was to investigate the effect of the diurnal pattern on initiation and steady-state gait variability in elderly inpatients.

METHOD

Thirty-seven elderly inpatients (28 women; mean age, 79.7 ± 9.5 years) who could walk without support were sampled in this study. The quantitative measure of gait variability was evaluated using the coefficient of variation (CV) based on four consecutive stride durations determined using triaxial accelerometers. Gait characteristics were evaluated during initiation and steady-state gait and defined as initiation CV and steady-state CV, respectively. This measurement was performed at two time points, morning and daytime.

RESULTS

There was no significant difference between initiation and steady-state gait characteristics in the daytime condition. However, in the morning condition, the initiation CV was higher than the steady-state CV. Furthermore, the initiation CV was higher in the morning than during daytime (p < 0.01).

CONCLUSION

Our study revealed that the variability of initiation gait is higher in the morning. It may be important to assess the risk of falls, including initiation gait, in the morning.

Diurnal gait fluctuations in single- and dual- task conditions

Gait is one of the most basic movements, and walking activity accomplished in dual task conditions realistically represents daily life mobility. Much is known about diurnal variations of gait components such as muscle power, postural control, and attention. However, paradoxically only little is known about gait itself. The aim of this study was to analyze whether gait parameters show time-of-day fluctuation in simple and dual task conditions. Sixteen young subjects performed sessions at five specific hours (06:00, 10:00, 14:00, 18:00 and 22:00 h), performing a single (walking or counting) and a dual (walking and counting) task. When performing gait in dual task conditions, an additional cognitive task had to be carried out. More precisely, the participants had to count backwards from a two-digit random number by increments of three while walking. Spatio-temporal gait parameters and counting performance data were recorded for analysis. Walking speed significantly decreased, while stride length variability increased when the task condition switched from single to dual. In the single-task condition, diurnal variations were observed in both walking speed and counting speed. Walking speed was higher in the afternoon and in the evening (14:00 and 22:00 h) and lower in the morning (10:00 h). Counting speed was maximum at 10:00 and 14:00 h and minimum at 18:00 h. Nevertheless, no significant diurnal fluctuation was substanytiated in the dual task condition. These results confirm the existing literature about changes in gait between single and dual task conditions. A diurnal pattern of single-task gait could also be highlighted. Moreover, this study suggests that diurnal variations faded in complex dual task gait, when the cognitive load nearly reached its maximum. These findings might be used to reduce the risk for falls, especially of the elderly.

Assessment of diurnal variation of stride time variability during continuous, overground walking in healthy young adults

BACKGROUND

There is emerging evidence that gait variability outcomes provide unique insights regarding the status of an individual's locomotor control system; however, there is currently limited evidence on the within-day reliability of stride time variability (STV) outcomes, or whether they demonstrate diurnal variation, when measured during continuous, overground walking in healthy young adults.

RESEARCH QUESTIONS

1) Are STV outcomes measured in the morning and afternoon during continuous, overground walking significantly different in healthy young adults? 2) What is the within-day reliability of STV outcomes measured during continuous, overground walking in healthy young adults?.

METHODS

Thirty-one healthy young adults (20.8 ± 3.7 years) completed two 10-minute continuous, overground walking trials on the same day (9:00-11:00am and 3:00-5:00pm) at their preferred walking speed. Data from a waist-mounted tri-axial accelerometer were used to determine the series of consecutive stride times for each trial.

RESULTS

There were no significant differences between sessions for average walking speed, average stride time, or STV. The within-day reliability was excellent for average walking speed and stride time, and generally poor to fair for STV.

SIGNIFICANCE

Healthy young adults do not appear to demonstrate diurnal variation in STV outcomes during continuous, overground walking; however, the development of a protocol to improve their reliability, as well as the establishment of normative ranges for such outcomes, would be beneficial to improve their application and interpretation in research and clinical settings.

Assessment of postural control after sleep deprivation with a low-cost portable force plate

It is well-known that acute sleep deprivation affects negatively postural control. The analysis of sleep quality during long periods and its impact on motor control and learning performance are crucial aspects of human health. Nevertheless, there is conflicting evidence regarding which postural control variables are more prone to change due to sleep deprivation. Moreover, very few clinicians have at their disposal expensive force plates to measure such variables, so the use of a low-cost portable device could be very interesting. Therefore, we aimed to identify which posture control variables, obtained from a low-cost plate, are more sensitive to sleep deprivation. In order to do so, we have performed a set of experiments with volunteers before and after a night without sleep. Eight participants took part of the study and had their balance measured by a Wii Balance Board before and after one night of sleep deprivation. They were asked to keep a quiet stance on top of the plate with their eyes open and closed, in a balanced design. The main results showed that, regardless the visual information, sleep deprivation has deepest impact on the anterior-posterior center of pressure displacement. Sleep deprivation without visual information had a more pronounced (large effect size) impact on the mean sway in the anterior-posterior direction and its distribution variation. The information that sleep deprivation has a more meaningful impact on anterior-posterior center of pressure excursion may help clinicians and healthcare professionals to better deal with its implications.

Time of day effect on balance performance, functional capacities and risk of fall in women with rheumatoid arthritis

Objective: This study explored the time of day effect of balance performance, functional capacities and risk of fall in three different times in patients with rheumatoid arthritis (RA) and the association between these variations and those of RA symptoms.Methods: A "discontinual" protocol, composed of three test sessions, carried out at 6 am, 2 pm and 10 pm was set up, in order to investigate the time of day effect of balance performance, functional capacities, risk of fall, stiffness, range of motion, swollen and painful joints in women with RA.Results: Time Up and Go Test (TUGT), Functional Reach Test (FRT) and tinetti test scores were significantly higher (p < .01) at 6 am and at 10 pm compared to 2 pm. Stiffness, range of motion, swollen and painful joints values were significantly higher (p < .01) at 6 am and at 10 pm compared to 2 pm. A significant difference was observed on the stiffness, range of motion and swollen joints values between 6 am and 10 pm that were higher at 6 am (p < .05).Using Pearson's coefficient, correlations were found between RA symptom values; and TUGT, FRT and Tinetti test scores.Conclusion: Results showed a time of day effect of balance performance, functional capacities and risk of falls in women with RA. This variation indicates an alteration of performance at 6 am and 10 pm. Fluctuations of stiffness, limited range of motion, swollen and painful joints noted are concomitant to those of balance performance, functional capacities, and risk of fall.Abbreviations: RA: rheumatoid arthritis; H&O questionnaire: Horne and Ostberg questionnaire; PSQI: Pittsburgh sleep quality index; HAQ: health assessment questionnaire; SF-36: the short form-36; WOMAC: Western Ontario and McMaster Universities Osteoarthritis Index; TUGT: Time Up and Go Test; FRT: Functional Reach Test.

Postural and vestibular changes related to CPAP treatment in moderate-to-severe OSA patients: a 12-month longitudinal study

PURPOSE

To assess whether vestibulo-ocular reflex (VOR) gain, posturography parameters and related clinical outcomes can improve in OSA patients after 12 months of CPAP treatment, taking into consideration that a certain degree of vestibular dysfunction has been identified in these subjects.

METHODS

Vestibular, postural, clinical, and polygraphic parameters were assessed in 32 OSA patients before and after beneficial CPAP treatment by means of video head impulse test (vHIT), static posturography (SP), Dizziness Handicap Inventory (DHI), Epworth Sleepiness Scale (ESS), and Apnea-Hypopnea Index (AHI), respectively, and were compared by means of a "within-subject" ANOVA model and Spearman's rank correlation.

RESULTS

After the 12-month period of treatment, OSA patients demonstrated a significant reduction in AHI values, in both opened and closed eyes conditions of surface and length as well as in power spectra recorded in low, middle, and high frequency interval. Although a significant improvement was also recorded among DHI and ESS scores, VOR gain increase did not survive to post-hoc corrections. Finally, positive correlations between the differences between pre- and post-treatment AHI, ESS, and PS values were found.

CONCLUSIONS

The present work highlighted that postural instability and dizziness-related conditions due to OSA may improve after 12 months of CPAP treatment. Although VOR gain did not demonstrate significant improvement, this study might open future perspectives directed to assessing VOR gain changes after longer periods of CPAP treatment.

Biopsychosocial Measures Related to Chronic Low Back Pain Postural Control in Older Adults

This study examined the biopsychosocial measures related to postural control in the growing population of older adults (i.e., 60 years and older). The sample of the study consisted of 129 older adults (M = 74.45, SD = 6.95), with 34 males and 95 females; 36 were classified with chronic low-back pain (CLBP), and 93 without chronic low-back pain (NCLBP). Physical and psychosocial constructs were analyzed as predictors for postural control measures. Additionally, gender and classification of low-back pain were examined as moderators for all physical and psychosocial measures. Results demonstrated that physical and psychosocial measures were able to significantly predict composite, visual, and vestibular balance measures, but not somatosensory or preference balance measures. The chair-stand test, modified sit-and-reach test, sleep disturbance, and balance efficacy were all identified as individually significant predictors. Gender and CLBP did not moderate the utility of any predictor variables. Results of the current study re-confirm the importance of utilizing the biopsychosocial approach for future research examining postural control in older adults.

Chronic Low Quality Sleep Impairs Postural Control in Healthy Adults

The lack of sleep, both in quality and quantity, is an increasing problem in modern society, often related to workload and stress. A number of studies have addressed the effects of acute (total) sleep deprivation on postural control. However, up to date, the effects of chronic sleep deficits, either in quantity or quality, have not been analyzed. Thirty healthy adults participated in the study that consisted of registering activity with a wrist actigraph for more than a week before performing a series of postural control tests. Sleep and circadian rhythm variables were correlated and the sum of activity of the least active 5-h period, L5, a rhythm variable, obtained the greater coefficient value with sleep quality variables (wake after sleep onset WASO and efficiency sleep). Cluster analysis was performed to classify subjects into two groups based on L5 (low and high). The balance tests scores used to asses postural control were measured using Biodex Balance System and were compared between the two groups with different sleep quality. The postural tests were divided into dynamic (platform tilt with eyes open, closed and cursor) and static (clinical test of sensory integration). The results showed that during the tests with eyes closed, the group with worse sleep quality had also worse postural control performance. Lack of vision impairs postural balance more deeply in subjects with chronic sleep inefficiency. Chronic poor sleep quality impairs postural control similarly to total sleep deprivation.

The impact of time of day on the gait and balance control of Alzheimer's patients

Alzheimer's patients suffer from circadian dysregulation. The aim of this study was to examine the evolution of balance control and gait at different times of the day (11:00, 14:00, 18:00) in order to identify whether Alzheimer's patients were more likely to fall at certain periods of the day. Spatio-temporal parameters of centre of foot pressure displacements were measured with a force platform and spatio-temporal parameters of walking were evaluated with a gait analysis device. The results highlighted that balance control was worse in the evening and the afternoon than in the morning. Furthermore, the walking speed was faster and support duration, swing duration and cycle duration were shorter in the evening than in the morning and afternoon. The combined analysis of balance control and gait parameters revealed that balance control and walking are concomitantly altered in the evening which increases the fall risk in the evening, in comparison with the morning, for Alzheimer's patients.

Diurnal Fluctuations of Verticality Perception - Lesser Precision Immediately after Waking up in the Morning

Internal estimates of direction of gravity are continuously updated by integrating vestibular, visual and proprioceptive input, and prior experience about upright position. Prolonged static roll-tilt biases perceived direction of gravity by adaptation of peripheral sensors and central structures. We hypothesized that in the morning after sleep, estimates of direction of gravity [assessed by the subjective visual vertical (SVV)] are less precise than in the evening because of adaptation to horizontal body position and lack of prior knowledge about upright position. Using a mobile SVV-measuring device, verticality perception was assessed in seven healthy human subjects on 7 days in the morning immediately after waking up and in the evening while sitting upright. Paired t-tests were applied to analyze diurnal changes in SVV trial-to-trial variability. Average SVV variability in the morning was significantly larger than in the evening (1.9 ± 0.6° vs. 0.9 ± 0.3°, p = 0.002). SVV accuracy was not significantly different (−1.2 ± 0.9° vs. −0.4 ± 0.4°, morning vs. evening, p = 0.058) and was within normal range (±2.3°) in all but one subject. A good night’s sleep has a profound effect on the brain’s ability to estimate direction of gravity. Resulting variability was significantly worse after waking up reaching values more than twice as large as in the evening while there was no significant impact on SVV accuracy. We hypothesize that lacking prior knowledge, adaptation of peripheral sensors, and lower levels of arousal and cerebral metabolism contribute to such impoverished estimates. Our observations have considerable clinical impact as they indicate an increased risk for falls and fall-related injuries in the morning.