Cardiometabolic disease risk in relation to objectively measured physical activity, sedentary behaviour in South African adults with knee and hip osteoarthritis.

PURPOSE: This study aimed to investigate the relationship between cardiometabolic disease risk and time spent in device-measured activity behaviours in a cohort of people with advanced osteoarthritis (OA) awaiting joint replacement surgery. MATERIALS AND METHODS: Cardiometabolic risk biomarkers were assessed in people with OA (n = 96; hip n = 38, knee n = 58; mean (SD) age = 64.3 (9.8) years; 71% female). Physical activity (PA) and sedentary behaviour (SB) were measured by accelerometer over seven days (24 h/day). RESULTS: There were similar patterns of PA and SB between the hip and knee OA participants except for total number of steps (hip = 3365 (2926) vs knee 4344 (2836) steps/day; p = 0.018) and total stepping time (hip = 50.8 (38.2) vs knee = 67.2 (38.5) min/day; p = 0.005). Each additional cardiometabolic risk factor accumulated was associated with a 26.3 min/day increase in sedentary behaviour (p = 0.032; 95% CI: 2.3, 50.2), a 26.3 min/day decrease in upright time (p = 0.032; -50.2, -2.3) and a 23.6 min/day decrease in standing time (p = 0.032; -45.1, -2.1). CONCLUSIONS: In people with hip or knee OA, increased cardiometabolic disease risk was associated with more sitting and less upright and standing time. Findings support targeting reductions in sedentary behaviour for improvements in cardiometabolic health in people with osteoarthritis.IMPLICATIONS FOR REHABILITATIONKnee and hip osteoarthritis is a condition which is associated with an increased risk of cardiometabolic disease but also due to the low levels of physical activity and high levels of sedentary behaviour.Offsetting sedentary behaviour with light physical activity offers a feasible interventional target to reduce the risk of cardiometabolic disease in people with hip and knee osteoarthritis.

Agreement between the activPAL accelerometer and direct observation during a series of gait and sit-to-stand tasks in people living with cervical dystonia.

Background: Accelerometers are commonly used for the assessment of PA; however, these devices have not been validated in people with dystonia who experience movement limitations. To properly understand movement behaviors and deliver accurate exercise prescription in this population, the validity of these devices must be tested. Objective: This study aimed to validate step count and postural transitions detected by the activPAL accelerometer (AP) against direct observation (DO) during two functional assessments: the 30-s sit-to-stand (30STS) and 6-min usual-pace walk tests. Methods: A total of 11 participants with cervical dystonia (CD) (male/female n = 5/6; mean age = 61 years; BMI = 24 kg/m2) performed the 6-min usual pace walking and 30STS while wearing the activPAL. A trained observer counted steps and observed the number of sit-to-stands. Results: The average step count detected with AP and DO was 651.8 (218-758) and 654.5 (287-798) respectively. The average transitions detected were 11 (4-16) and 12 (4-17) respectively. Both methods showed good agreement and there was a statistically significant and strong correlation between the two methods, i.e., transitions (r = 0.983, p = 0.0001), and step counts (r = 0.9841, p = 0.0001). Conclusion: There is a good agreement between activPAL and direct observation for step counts and transitions between sitting and standing in people living with CD.

Moving beyond moderate-to-vigorous physical activity: the role of light physical activity during adolescence.

Regular physical activity is an important component of a healthy lifestyle for young people. However, an estimated 80% of adolescents globally are insufficiently active. Traditionally, health benefits were attributed only to physical activity of at least moderate intensity, and recommendations focused on achieving a threshold of moderate-to-vigorous physical activity, without consideration of other aspects of movement within the 24 h cycle. Recently, the overall daily balance of active and sedentary behaviours has gained recognition as an important determinant of health. However, the relationship between light intensity physical activity and health has not been fully explored. In this perspective paper, we discuss key challenges in defining, measuring and analysing light physical activity which have hindered the advancement of knowledge in this area. Next, we suggest three ways in which light physical activity may enhance adolescent wellbeing: firstly, by replacing sedentary behaviours to increase daily movement; secondly, by supporting the accumulation of higher intensities of physical activity; and thirdly, by providing positive experiences to facilitate lifelong engagement with physical activity. In highlighting the importance of light physical activity during adolescence, we aim to encourage critical reflection and the exploration of new approaches towards physical activity within public health and beyond.

Correction: Could the ketogenic diet induce a shift in thyroid function and support a metabolic advantage in healthy participants? A pilot randomized-controlled-crossover trial.

[This corrects the article DOI: 10.1371/journal.pone.0269440.].

Could the ketogenic diet induce a shift in thyroid function and support a metabolic advantage in healthy participants? A pilot randomized-controlled-crossover trial.

BACKGROUND: The ketogenic diet (KD) has been shown to result in body mass loss in people with disease as well as healthy people, yet the effect of the KD on thyroid function and metabolism are unknown. OBJECTIVE: We aimed to determine the effects of a KD, compared with an isocaloric high-carbohydrate low-fat (HCLF) diet, on resting metabolic rate and thyroid function in healthy individuals. DESIGN: Eleven healthy, normal-weight participants (mean(SD) age: 30(9) years) completed this randomized crossover-controlled study. For a minimum of three weeks on each, participants followed two isocaloric diets: a HCLF diet (55%carbohydrate, 20%fat, 25%protein) and a KD (15%carbohydrate, 60%fat, 25% protein), with a one-week washout period in-between. Importantly, while on the KD, the participants were required to remain in a state of nutritional ketosis for three consecutive weeks. Crossover analyses and linear mixed models were used to assess effect of diet on body mass, thyroid function and resting metabolic rate. RESULTS: Both dietary interventions resulted in significant body mass loss (p<0.05) however three weeks of sustained ketosis (KD) resulted in a greater loss of body mass (mean (95%CI): -2.9 (-3.5, -2.4) kg) than did three weeks on the HCLF diet (-0.4 (-1.0, 0.1) kg, p < 0.0001). Compared to pre-diet levels, the change in plasma T3 concentration was significantly different between the two diets (p = 0.003), such that plasma T3 concentration was significantly lower following the KD diet (4.1 (3.8, 4.4) pmol/L, p<0.0001) but not different following the HCLF diet (4.8 (4.5, 5.2) pmol/L, p = 0.171. There was a significant increase in T4 concentration from pre-diet levels following the KD diet (19.3 (17.8, 20.9) pmol/L, p < 0.0001), but not following the HCLF diet (17.3 (15.7, 18.8) pmol.L, p = 0.28). The magnitude of change in plasma T4 concentration was not different between the two diets (p = 0.4). There was no effect of diet on plasma thyroid stimulating hormone concentration (p = 0.27). There was a significantly greater T3:T4 ratio following the HCLF diet (0.41 (0.27, 0.55), p < 0.0001) compared to pre-diet levels but not following the KD diet (0.25 (0.12, 0.39), p = 0.80). CONCLUSIONS: Although the diets were isocaloric and physical activity and resting metabolic rate remained constant, the participants lost more mass after the KD than after the HCLF diet. The observed significant changes in triiodothyronine concentration suggest that unknown metabolic changes occur in nutritional ketosis, changes that warrant further investigation. TRIAL REGISTRATION: Pan African Clinical Trial Registry: PACTR201707002406306 URL: https://pactr.samrc.ac.za/.

Relationships between Physical Activity, Work Ability, Absenteeism and Presenteeism in Australian and New Zealand Adults during COVID-19.

Public health movement and social restrictions imposed by the Australian and New Zealand governments in response to the COVID-19 pandemic influenced the working environment and may have affected health behaviours, work ability, and job performance. The aim of this study was to determine the associations between health behaviours and work ability and performance during COVID-19 restrictions and if health behaviours were related to demographic or population factors. A cross-sectional survey was used to gather responses from 433 adult employees in Australia and New Zealand between June and August 2020. The survey requested demographic information and used the International Physical Activity Questionnaire, Work Ability Index, and the World Health Organisation's Health and Work Performance Questionnaire. Multivariate regression models were used to explore relationships between the identified variables while controlling for several possible confounders. Being sufficiently physically active was associated with higher reported physical (aOR = 2.1; p = 0.001) and mental work abilities (aOR = 1.8; p = 0.007) and self-reported job performance (i.e., lower presenteeism) (median +7.42%; p = 0.03). Part-time employees were 56% less likely (p = 0.002) to report a good or very good mental work ability. Those with existing medical conditions were 14% less likely (p = 0.008) to be sufficiently active and 80% less likely (p = 0.002) to report rather good or very good physical work ability. Being sufficiently active was associated with higher physical and mental work abilities and better job performance during the COVID-19 pandemic. Employers should support opportunities for regular physical activity and provide specific support to individuals with medical conditions or in part-time employment.

The Effect of the COVID-19 Pandemic Movement Restrictions on Self-Reported Physical Activity and Health in New Zealand: A Cross-Sectional Survey.

This study describes self-reported physical activity (PA), motivation to exercise, physical and mental health and feelings towards PA during the March-May 2020 COVID-19 lockdown in New Zealand. Adults over the age of 18 years (n = 238; 80.2% female) completed the International Physical Activity Questionnaire (IPAQ), the Behavioural Regulation in Exercise Questionnaire 3, the Short Form-36 and open-ended questions about PA through an anonymous online survey. Regular exercise was undertaken by 85% of respondents prior to lockdown, but only 49.8% were able to maintain their usual level of PA. Although respondents were considered sufficiently physically active from the IPAQ, 51.5% reported not being able to maintain their usual level of PA primarily due to the closure of their gym facilities. Sixty percent of respondents reported that PA had a positive effect on their overall wellbeing. When asked to specify which aspects of wellbeing were affected, the effect on mental health was reported the most while the effect on body image or fitness was reported the least. Strategies to increase or maintain engagement in physical activity during lockdowns should be encouraged to promote positive mental health during the COVID-19 pandemic.

Neurorehabilitation in dystonia: a holistic perspective.

Rehabilitation for isolated forms of dystonia, such as cervical or focal hand dystonia, is usually targeted towards the affected body part and focuses on sensorimotor control and motor retraining of affected muscles. Recent evidence, has revealed people who live with dystonia experience a range of functional and non-motor deficits that reduce engagement in daily activities and health-related quality of life, which should be addressed with therapeutic interventions. These findings support the need for a holistic approach to the rehabilitation of dystonia, where assessment and treatments involve non-motor signs and symptoms, and not just the dystonic body part. Most studies have investigated Cervical Dystonia, and in this population, it is evident there is reduced postural control and walking speed, high fear of falling and actual falls, visual compensation for the impaired neck posture, and a myriad of non-motor symptoms including pain, fatigue, sleep disorders and anxiety and depression. In other populations of dystonia, there is also emerging evidence of falls and reduced vision-related quality of life, along with the inability to participate in physical activity due to worsening of dystonic symptoms during or after exercise. A holistic approach to dystonia would support the management of a wide range of symptoms and signs, that if properly addressed could meaningfully reduce disability and improve quality of life in people living with dystonia.

Improvements in Objectively Measured Activity Behaviors Do Not Correlate With Improvements in Patient-Reported Outcome Measures Following Total Knee Arthroplasty.

BACKGROUND: Activity monitors have added a new dimension to our ability to objectively measure physical activity in patients undergoing total knee arthroplasty (TKA). The aim of the study is to assess whether changes in the time spent sitting, standing, and stepping were associated with changes in patient-reported outcome measures (PROMs) before and after TKA. METHODS: Valid activPAL data (>3 days) and PROMs were obtained from 49 men and women (mean [SD] age, 62.8 [8.6] years; body mass index, 33.8 [7.1] kg/m2) who underwent primary TKA, before and at 6 weeks or 6 months after surgery. Patient-reported symptoms of pain, stiffness, and knee function were obtained using the Knee injury and Osteoarthritis Outcome Score and Oxford Knee Score questionnaires. RESULTS: Mean (SD) Knee injury and Osteoarthritis Outcome Score (80.1 [16.3] to 41.6 [6.5], P < .001) and Oxford Knee Score (12.0 [9.8] to 17.7 [22.8], P < .001) scores improved 6 months after TKA. Walking time (mean [95% confidence interval]; min/d) increased from before (79 [67-91]) to 6 months after TKA (101 [88-114], P = .006). Standing time (318 [276-360] to 321 [291-352], P = .782) and sitting time (545 [491-599] to 509.0 [459.7-558.3], P = .285) did not change from before to 6 months after TKA. Participants took more steps (2559 [2128-2991] to 3515 [2983-4048] steps/day, P = .001) and accumulated more steps (31 [30-34] to 34 [33-35] steps/min, P < .001) after TKA compared to before. There were no associations between changes in activity behaviors and changes in PROMs (P > .05). CONCLUSION: Despite improvements in self-reported knee pain and functional ability, these changes do not correlate with improvements in objectively measured light-intensity and sedentary activity behaviors.

Physical Activity, Sedentary Behavior, and Barriers to Exercise in People Living With Dystonia.

Background: Dystonia is a neurological movement disorder that presents as sustained or intermittent involuntary muscle contractions causing abnormal postures and movements. Knowledge of dystonia is mostly at the impairment level with minimal understanding of activity and participation limitations. Physical activity (PA) is an important aspect of neurological disease management, with wide-ranging benefits for overall health and quality of life. No studies have quantified PA and sedentary behavior (SB), nor explored barriers to being physically active in people with dystonia. Methods: Participants diagnosed with any form of dystonia completed a mixed-methods anonymous online survey on activity behaviors. The International Physical Activity Questionnaire (IPAQ) and Adult Sedentary Behavior Questionnaire (SBQ) assessed self-reported PA and SB. Barriers to exercise engagement were investigated according to the five-factor social-ecological framework and dystonia-specific questions regarding the impact of exercise on symptoms were included. Results: Two-hundred and sixty-three participants consented to the study (mean (SD) age = 55 (13) years, 76% Female). A large proportion of respondents (40%) reported living with cervical dystonia (CD). Overall, the median (IQR) time spent in walking, moderate, and vigorous activity was 60 (0-120), 120 (15-300), and 0 (0-13) min/day, respectively. SB time during weekdays was 285.0 (157.5-465.0) min/day and 345.0 (195.0-502.5) min/day on weekends. Fifty-five percent of participants were dissatisfied with their current level of PA and 75% reported dystonia had decreased their level of PA. Fifty-seven percent found their symptoms were worsened during exercise though the after-effects on symptoms varied. Fatigue, motor symptoms, pain, and poor balance were commonly cited limiting factors. Qualitative and quantitative data indicated difficulties with more vigorous intensity activity. The common barriers to engagement were personal and governmental factors, such as physical impairments, lack of funding and lack of trained exercise professionals. Conclusion: While more than half of respondents indicated they were not satisfied with their current level of PA, and exercise primarily worsened their dystonia symptoms, most participants were meeting the minimum guidelines. Future studies should incorporate robust objective methods of PA and SB measurement and explore the causal mechanisms underpinning exercise-induced aggravation of dystonic symptoms to further enhance life participation of people living with dystonia.

Three consecutive weeks of nutritional ketosis has no effect on cognitive function, sleep, and mood compared with a high-carbohydrate, low-fat diet in healthy individuals: a randomized, crossover, controlled trial.

BACKGROUND: The high-fat ketogenic diet (KD) has become an increasingly popular diet not only in overweight/obese populations, or those with clinical conditions, but also in healthy non-overweight populations. OBJECTIVE: Because there are concerns about the association between high-fat diets and cognitive decline, this study aimed to determine the effects of a KD compared with an isocaloric high-carbohydrate, low-fat (HCLF) diet on cognitive function, sleep, and mood in healthy, normal-weight individuals. METHODS: Eleven healthy, normal-weight participants (mean age: 30 ± 9 y) completed this randomized, controlled, crossover study. Participants followed 2 isocaloric diets-an HCLF diet (55% carbohydrate, 20% fat, and 25% protein) and a KD (15% carbohydrate, 60% fat, and 25% protein)-in a randomized order for a minimum of 3 wk, with a 1-wk washout period between diets. Measures of ß-hydroxybutyrate confirmed that all participants were in a state of nutritional ketosis during post-KD assessments (baseline: 0.2 ± 0.2 mmol/L; KD: 1.0 ± 0.5 mmol/L; washout: 0.2 ± 0.1 mmol/L; and HCLF: 0.3 ± 0.2 mmol/L). Cognitive function was assessed using a validated, psychological computer-based test battery before and after each diet. Subjective measures of mood and sleep were also monitored throughout the study using validated scales. RESULTS: Three weeks of sustained nutritional ketosis, compared with the HCLF diet, had no effect on speed and accuracy responses in tasks designed to measure vigilance (speed: P = 0.39, Cohen's d = 0.26; accuracy: P = 0.99, Cohen's d = 0.04), visual learning and memory (speed: P = 0.99, Cohen's d = 0.04; accuracy: P = 0.99, Cohen's d = 0.03), working memory (speed: P = 0.62, Cohen's d = 0.26; accuracy: P = 0.98, Cohen's d = 0.07), and executive function (speed: P = 0.60, Cohen's d = 0.31; accuracy: P = 0.90, Cohen's d = 0.19). Likewise, mood, sleep quality, and morning vigilance did not differ (P > 0.05) between the dietary interventions. CONCLUSION: The results of our randomized, crossover, controlled study suggest that 3 wk of sustained nutritional ketosis had no effect on cognitive performance, mood, or subjective sleep quality in a sample of healthy individuals. This trial was registered in the Pan African Clinical Trial Registry as PACTR201707002406306.

Light intensity physical activity increases and sedentary behavior decreases following total knee arthroplasty in patients with osteoarthritis.

PURPOSE: To describe objectively measured changes in the volume and pattern of physical activity and sedentary behavior in patients undergoing total knee arthroplasty for osteoarthritis. METHODS: Physical activity and sedentary behavior were measured in patients (13 males, 76 females) with a mean age of 64 years (range 55-80) and end-stage osteoarthritis of the knee, using an accelerometer (ActiGraph GT3X+) for seven consecutive days (24 h/day) prior to, 6 weeks and 6 months after total knee arthroplasty. Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), University of California Los Angeles (UCLA) Activity index and range of motion (ROM) were also assessed. RESULTS: Proportion of time spent in sedentary behavior decreased from baseline to 6 months (mean 70.1 vs. 64.0%; p = 0.009) and the interruptions to sedentary behavior improved between baseline and 6 months after total knee arthroplasty (mean 85.0-93.0 breaks/day, p = 0.014). Proportion of time spent in light physical activity increased from baseline to 6 months after total knee arthroplasty (29.0 vs. 34.8%; p = 0.008). There was no change in time spent in moderate to vigorous physical activity after total knee arthroplasty. WOMAC (median 71.0 vs. 4.0, p < 0.001), UCLA (median 2.0 vs. 5.0, p < 0.001) as well as ROM [median (0.0°-90.0°) vs. (0.0°-110°), p < 0.05] scores improved between baseline and 6 months after total knee arthroplasty. CONCLUSION: Clinically, functional improvements in patients following total knee arthroplasty may be assessed by objectively measuring changes in low intensity activity behaviors. The use of accelerometers in this study gives new insights into activity accumulation patterns in a clinical population and highlights their use in determining a behavioral response to an intervention. LEVEL OF EVIDENCE: II.

The Effect of Interrupting Sedentary Behavior on the Cardiometabolic Health of Adults With Sedentary Occupations: A Pilot Study.

OBJECTIVE: The aim of this study was to determine whether mobile phone text messages could modify objectively measured sedentary behavior and cardiometabolic health in office workers. METHODS: Nine males and 12 females [mean (SD): 27.5 (5.7) years, 23.8 (2.8) kg/m] were assigned to a control (CON) or intervention (PROMPT) group. PROMPT received an activity-promoting text message during office hours. Participants wore an actiGraph and activPAL accelerometer for 7 days during and after the intervention. Blood pressure, lipid, and metabolic profiles were measured before and after the intervention. RESULTS: PROMPT sat less [mean (95% confidence interval, 95% CI): 4.9 (4.4 to 5.4) hours/day] than CON [6.0 (5.5 to 6.4) hours/day; P = 0.04] during the message-receiving period. There was no difference between groups after the intervention and for the other activity variables. There were no changes in cardiometabolic health markers following the intervention. CONCLUSION: Sitting time was lower during the message-receiving period, but the difference between groups was no longer apparent after the intervention.

The effect of a ketogenic diet versus a high-carbohydrate, low-fat diet on sleep, cognition, thyroid function, and cardiovascular health independent of weight loss: study protocol for a randomized controlled trial.

BACKGROUND: Many physiological health benefits observed after following a ketogenic diet (KD) can be attributed to the associated weight loss. The KD has become more prominent as a popular health choice, not only in obese/overweight individuals, but also in healthy adults. The study aims to determine the effects of a KD, independent of weight loss, on various aspects of physiological health including: sleep, thyroid function, cognition, and cardio-metabolic health. The study will also aim to determine whether a change in basal metabolic rate may be associated with any changes observed. METHODS: Twenty healthy men and women between 18 and 50 years of age will take part in this study. In a randomized controlled, cross-over design, participants will follow two isocaloric diets: a high-carbohydrate, low-fat diet (55% CHO, 20% fat, 25% protein) and a KD (15% CHO, 60% fat, 25% protein). Each dietary intervention will last for a minimum of 3 weeks, with a 1-week washout period in between. Before and after each diet, participants will be assessed for sleep quality, cognitive function, thyroid function, and basal metabolic rate. A blood sample will also be taken for the measurement of cardio-metabolic and immune markers. DISCUSSION: The present study will help in understanding the potential effects of a KD on aspects of physiological health in healthy adults, without the confounding factor of weight loss. The study aims to fill a significant void in the academic literature with regards to the benefits and/or risks of a KD in a healthy population, but will also explore whether diet-related metabolic changes may be responsible for the changes observed in physiological health. TRIAL REGISTRATION: Pan African Clinical Trial Registry ( www.pactr.org ), trial number: PACTR201707002406306 . Registered on 20 July 2017.

Sedentary Behavior in Patients With Knee Osteoarthritis Before and After Total Knee Arthroplasty: A Systematic Review.

OBJECTIVE: The objective of this systematic review is to integrate the available evidence on changes in sedentary behavior (SB) in patients with knee osteoarthritis after total knee arthroplasty (TKA). METHODS: A systematic literature search from January 2002 to October 31, 2017, was performed for studies assessing objectively and/or subjectively measured SB following TKA. The Scottish Intercollegiate Guidelines Network Methodology appraisal tool was used to critically appraise the methodological quality of the included studies. RESULTS: Ten studies reporting on SB with a total of 1,028 participants were included in the review. Three studies reported changes in SB with two showing a reduction in SB and one (with high risk of bias) an increase in SB after TKA. Seven studies showed no change in SB following TKA. CONCLUSION: Currently, there is insufficient evidence which suggests that SB time improves following TKA. Detailed assessments of SB after TKA are needed.

Radial and tibial bone indices in athletes participating in different endurance sports: a pQCT study.

Low magnitude bone-loading sports may benefit bone structure and strength in the exercised limbs. This study compared peripheral quantitative computed tomography measures of radial and tibial diaphyseal strength (strength-strain index, SSI), structure (total area (ToA) and cortical area (CoA), density (CoD) and thickness (CT), and circumferences), muscle cross-sectional area (MCSA) and strength (one-repetition maximum, 1-RM) in male endurance athletes taking part in (i) non-weight-bearing and non-impact sports: swimmers (SWIM, n = 13) and road cyclists (RC, n = 10), (ii) non-weight-bearing, impact sport: mountain bikers (MB, n = 10), (iii) weight bearing and impact sport: runners (RUN, n = 9). All athlete groups were also compared to sedentary controls (CON, n = 10). Arm MCSA, 1-RM and radial bone size and strength tended to be greater in SWIM than CON and/or RC (ToA, %difference ± 95%CI, SWIM-CON: 14.6% ± 12.7%; SWIM-RC: 12.9% ± 10.7%) but not different to MB and RUN. RUN had bigger tibial CoA than CON, SWIM and RC (CoA, RUN-CON: 12.1% ± 10.7%; RUN-SWIM: 10.9% ± 9.4%; RUN-RC: 15.8% ± 9.5%) without marked changes in tibial strength indices, lower-limb MCSA or 1-RM. Both MB and RC failed to display any difference in tibial indices, lower-limb MCSA and 1-RM compared to CON. In swimmers, the bone structure and strength of the primary exercised limbs, the arms, is greater than controls and road cyclists. Conversely, although runners experience impact and weight-bearing loading, tibial structure is greater without a substantial difference in tibial strength compared to controls and non-impact sports. Failure to observe a difference in tibial indices in MB and RC compared to controls is unexpected.

Rationale, design and protocol of a longitudinal study assessing the effect of total knee arthroplasty on habitual physical activity and sedentary behavior in adults with osteoarthritis.

BACKGROUND: Physical activity levels are decreased and sedentary behaviour levels are increased in patients with knee osteoarthritis (OA). However, previous studies have shown that following total knee arthroplasty (TKA), objectively measured physical activity levels do not change compared to before the surgery. Very few studies have objectively assessed sedentary behaviour following TKA. This study aims to assess patterns of objective habitual physical activity and sedentary behaviour in patients with knee OA and to determine whether these change following TKA. METHODS: Patients diagnosed with knee osteoarthritis and scheduled for unilateral primary total knee arthroplasty will be recruited from the Orthopaedic Division at the Charlotte Maxeke Johannesburg Academic Hospital. Eligible participants will have assessments completed one week before the scheduled arthroplasty, six weeks, and six months post-operatively. The primary outcomes are habitual physical activity and sedentary behaviour which will be measured using accelerometry (Actigraph GTX3+ and activPal monitors) at the specific time points. The secondary outcomes will be improvements in osteoarthritis-specific quality of life measures using the following questionnaires: Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Knee injury and Osteoarthritis Outcome Score (KOOS), Oxford Knee Score (OKS), Knee Society Clinical Rating System (KSS), UCLA activity index; subjective pain scores, and self reported sleep quality. DISCUSSION: The present study will contribute to the field of musculoskeletal health by providing a rich detailed description of the patterns of accumulation of physical activity and sedentary behaviour in patients with knee OA. These data will contribute to existing knowledge using an objective measurement for the assessment of functional ability after total knee arthroplasty. Although studies have used accelerometry to measure physical activity in knee OA patients, the data provided thus far have not delved into the detailed patterns of how and when physical activity is accumulated before and after TKA. Accurate assessment of physical activity is important for physical activity interventions that target special populations. TRIAL REGISTRATION: NCT02675062 (4 February 2016).

The effect of loading and ethnicity on annual changes in cortical bone of the radius and tibia in pre-pubertal children.

BACKGROUND: It is unclear what effect habitual physical activity or ethnicity has on annual changes in bone size and strength in pre-pubertal children. AIM: To determine whether the annual relative change in bone size and strength differed between high and low bone loaders and also between black and white pre-pubertal children. SUBJECTS AND METHODS: Peripheral quantitative computed tomography (pQCT) scans of the 65% radius and tibia were completed on 41 black and white children (15 boys, 26 girls) between the ages of 8-11 years, at baseline and 1 year later. Children were categorised into either a high or low bone loading group from a peak bone strain score obtained from a bone-specific physical activity questionnaire. Total area (ToA), cortical area (CoA), cortical density (CoD), strength-strain index (SSI), periosteal circumference (PC), endosteal circumference (EC) and cortical thickness (CT) were assessed. RESULTS: There was no difference in annual relative change in radial or tibia bone size and strength between the low and high bone loaders. Black children had a greater annual relative change in CoD (p = 0.03) and SSI (p = 0.05) compared to the white children. CONCLUSION: Children who performed high bone loading activities over a 1-year period had similar bone growth to children who did low bone loading activities over the same period. Rapid maturational growth over this period may have resulted in bone adapting to the strains of habitual physical activity placed on it. Black children may have greater tibial bone strength compared to white children due to a greater annual increase in cortical density.

A two-year history of high bone loading physical activity attenuates ethnic differences in bone strength and geometry in pre-/early pubertal children from a low-middle income country.

We examined the interplay between ethnicity and weight-bearing physical activity on the content and volumetric properties of bone in a pre- to early pubertal South African Black and White population. Sixty six children [Black boys, 10.4 (1.4)yrs, n=15; Black girls, 10.1 (1.2)yrs, n=27; White boys, 10.1 (1.1)yrs, n=7; White girls, 9.6 (1.3)yrs, n=17] reported on all their physical activities over the past two years in an interviewer administered physical activity questionnaire (PAQ). All participants underwent a whole body and site-specific DXA scan and we also assessed bone structure and estimated bone strength with pQCT. Children were classified as being either high or low bone loaders based on the cohort's median peak bone strain score estimated from the PAQ. In the low bone loading group, Black children had greater femoral neck bone mineral content (BMC) (2.9 (0.08)g) than White children (2.4 (0.11)g; p=0.05). There were no ethnic differences in the high bone loaders for femoral neck BMC. At the cortical site, the Black low bone loaders had a greater radius area (97.3 (1.3) vs 88.8 (2.6)mm(2); p=0.05) and a greater tibia total area (475.5 (8.7) vs. 397.3 (14.0)mm(2); p=0.001) and strength (1633.7 (60.1) vs. 1271.8 (98.6)mm(3); p=0.04) compared to the White low bone loaders. These measures were not different between the Black low and high bone loaders or between the Black and White high bone loaders. In conclusion, the present study shows that there may be ethnic and physical activity associations in the bone health of Black and White pre-pubertal children and further prospective studies are required to determine the possible ethnic specific response to mechanical loading.