Quantifying Habitual Levels of Physical Activity According to Impact in Older People: Accelerometry Protocol for the VIBE Study

Associations of accelerometer-estimated free-living daily activity impact intensities with 10-year probability of osteoporotic fractures in adults

PURPOSE

Accelerometers are used to objectively measure physical activity; however, the relationship between accelerometer-based activity parameters and bone health is not well understood. This study examines the association between accelerometer-estimated daily activity impact intensities and future risk estimates of major osteoporotic fractures in a large population-based cohort.

METHODS

Participants were 3165 adults 46 years of age from the Northern Finland Birth Cohort 1966 who agreed to wear a hip-worn accelerometer during all waking hours for 14 consecutive days. Raw accelerometer data were converted to resultant acceleration. Impact magnitude peaks were extracted and divided into 32 intensity bands, and the osteogenic index (OI) was calculated to assess the osteogenic effectiveness of various activities. Additionally, the impact peaks were categorized into three separate impact intensity categories (low, medium, and high). The 10-year probabilities of hip and all major osteoporotic fractures were estimated with FRAX-tool using clinical and questionnaire data in combination with body mass index collected at the age of 46 years. The associations of daily activity impact intensities with 10-year fracture probabilities were examined using three statistical approaches: multiple linear regression, partial correlation, and partial least squares (PLS) regression.

RESULTS

On average, participants' various levels of impact were 8331 (SD = 3478) low; 2032 (1248) medium; and 1295 (1468) high impacts per day. All three statistical approaches found a significant positive association between the daily number of low-intensity impacts and 10-year probability of hip and all major osteoporotic fractures. In contrast, increased number of moderate to very high daily activity impacts was associated with a lower probability of future osteoporotic fractures. A higher OI was also associated with a lower probability of future major osteoporotic fractures.

CONCLUSION

Low-intensity impacts might not be sufficient for reducing fracture risk in middle-aged adults, while high-intensity impacts could be beneficial for preventing major osteoporotic fractures.

Daily Pain Severity but Not Vertebral Fractures Is Associated With Lower Physical Activity in Postmenopausal Women With Back Pain

Back pain lifetime incidence is 60%-70%, while 12%-20% of older women have vertebral fractures (VFs), often with back pain. We aimed to provide objective evidence, currently lacking, regarding whether back pain and VFs affect physical activity (PA). We recruited 69 women with recent back pain (age 74.5 ± 5.4 years). Low- (0.5 < g < 1.0), medium- (1.0 ≤ g < 1.5), and high-impact (g ≥ 1.5) PA and walking time were measured (100 Hz for 7 days, hip-worn accelerometer). Linear mixed-effects models assessed associations between self-reported pain and PA, and group differences (VFs from spine radiographs/no-VF) in PA. Higher daily pain was associated with reduced low (β = -0.12, 95% confidence interval, [-0.22, -0.03], p = .013) and medium-impact PA (β = -0.11, 95% confidence interval, [-0.21, -0.01], p = .041), but not high-impact PA or walking time (p > .11). VFs were not associated with PA (all p > .2). Higher daily pain levels but not VFs were associated with reduced low- and medium-impact PA, which could increase sarcopenia and falls risk in older women with back pain.

Musculoskeletal health and life-space mobility in older adults: Findings from the Hertfordshire Cohort Study

This study explores the relationship between musculoskeletal conditions of ageing and life-space mobility (LSM) in 1110 community-dwelling older adults from the Hertfordshire Cohort Study. LSM is a novel measure which captures ability to mobilise within the home, locally and more widely. Among men, older age, care receipt, not driving a car, lower wellbeing, and reduced physical function were associated with lower LSM, while in women only driving status and physical function were associated with LSM. Osteoporosis, arthritis, and fractures had no significant associations with LSM in either gender. These findings provide support for sex-specificity in the determinants of LSM and inform novel approaches to improving mobility and health in older age.

Changes in femoral neck bone mineral density and structural strength during a 12-month multicomponent exercise intervention among older adults - Does accelerometer-measured physical activity matter?

Age-related bone loss is to some extent unavoidable, but it may be decelerated with regular exercise continued into older age. Daily physical activity alongside structured exercise may be an important stimulus for maintaining bone strength, but the relationships of habitual physical activity with bone strength are sparsely investigated in older adults. Therefore, the main aim was to investigate if accelerometer-derived impact-based and intensity-minute-based measures of physical activity were associated with changes in femoral neck bone traits during a 12-month exercise intervention among community-dwelling older men and women. Data comes from the PASSWORD study (ISRCTN52388040), a year-long multicomponent exercise intervention. Participants were 299 older adults (mean age 74 ± 4 years, 58 % women), who self-reported not to meet the physical activity guidelines for older adults but did not have any contraindications for exercising. The multicomponent training program included both supervised and self-administered exercises aimed at improving muscle strength, postural balance, and aerobic endurance. Physical activity was assessed at baseline and at six months into the intervention, and femoral neck bone properties at baseline and at twelve months. Physical activity measures were accelerometer-measured mean daily osteogenic index score, low, medium, and high intensity impact counts, and sedentary, light, and moderate-to-vigorous intensity activity minutes. Femoral neck bone mineral density (BMD) was measured with DXA and structural strength indicators (cross-sectional area [CSA] and section modulus) were subsequently derived from hip structural analysis. Longitudinal associations of physical activity and bone outcomes were analyzed with generalized estimating equation linear models. Sex was included as a moderating factor, and models were further adjusted by potentially confounding factors (age, height, weight, smoking status, medications, chronic disease conditions, and strength training adherence). Participants increased their physical activity by all measures and decreased their sedentary time from baseline to six months. BMD decreased from baseline to post-intervention, while CSA maintained stable and section modulus slightly increased. Osteogenic index, high impacts, and moderate-to-vigorous intensity physical activity, measured across the first half of the study, were positively associated with changes in BMD over 12 months (time х physical activity interaction effect: ß = 0.065, 95 % CI [0.004, 0.126]; ß = 0.169, 95 % CI [0.048, 0.289]; and ß = 0.151, 95 % CI [0.016, 0.286], respectively). That is, the higher the physical activity was, the smaller was the decline in BMD. Any physical activity measure was not associated with changes in CSA or section modulus in the full study sample. Sex did not significantly moderate the longitudinal associations, except the association between sedentary time and CSA (sex х time х PA interaction effect: ß = -0.017, 95 % CI [-0.033, -0.002]). An inverse association was found between sedentary time and changes in CSA in women, but not in men. In conclusion, BMD decline was less pronounced in individuals who accumulated more accelerometer-measured daily physical activity at the intensity of very brisk walking or light lateral jumping or higher intensities in a sample of relatively healthy, previously physically inactive older adults. Our findings support that accumulating the recommended amount of 150 or more weekly minutes of moderate-to-vigorous physical activity is also beneficial for older adults' bone health when incorporated into a multicomponent exercise program.

The effects of combined amplitude and high-frequency vibration on physically inactive osteopenic postmenopausal women

Purpose: To evaluate whole-body vibration (WBV) osteogenic potential in physically inactive postmenopausal women using high-frequency and combined amplitude stimuli.

Methods: Two-hundred fifty-five physically inactive postmenopausal women (55–75 years) with 10-year major osteoporotic fracture risk (3%–35%) participated in this 18-month study. For the first 12 months, the vibration group experienced progressive 20-min WBV sessions (up to 3 sessions/week) with rest periods (30–60 s) between exercises. Frequencies (30–50 Hz), with low (0.2–0.4 mm) and high (0.6–0.8 mm) amplitude stimuli were delivered via PowerPlate Pro5 platforms producing accelerations of (0.75–7.04 g). The last 6 months for the treatment group were a follow-up period similar to control. Serum bone remodelling markers [C-terminal crosslinked telopeptide of type-1 collagen (CTX), procollagen type-1 N-terminal propeptide (P1NP), bone alkaline phosphatase (BAP) and sclerostin] were measured at fasting. CTX and P1NP were determined by automated chemiluminescence immunoassay, bone alkaline phosphatase (BAP) by automated spectrophotometric immunoassay, and sclerostin by an enzyme-immunoassay. Bone mineral density (BMD) of the whole-body, proximal femur and lumbar vertebrae was measured by dual-energy X-ray absorptiometry (DXA). Bone microarchitecture of the distal non-dominant radius and tibia was measured by high-resolution peripheral quantitative computed tomography (HR-pQCT).

Results: Femoral neck (p = 0.520) and spine BMD (p = 0.444) failed to improve after 12 months of WBV. Bone macro and microstructural parameters were not impacted by WBV, as well as estimated failure load at the distal radius (p = 0.354) and tibia (p = 0.813). As expected, most DXA and HR-pQCT parameters displayed age-related degradation in this postmenopausal population. BAP and CTX increased over time in both groups, with CTX more marginally elevated in the vibration group when comparing baseline changes to month-12 (480.80 pmol/L; p = 0.039) and month-18 (492.78 pmol/L; p = 0.075). However, no differences were found when comparing group concentrations only at month-12 (506.35 pmol/L; p = 0.415) and month-18 (518.33 pmol/L; p = 0.480), indicating differences below the threshold of clinical significance. Overall, HR-pQCT, DXA bone parameters and bone turnover markers remained unaffected.

Conclusion: Combined amplitude and high-frequency training for one year had no ameliorating effect on DXA and HR-pQCT bone parameters in physically inactive postmenopausal women. Serum analysis did not display any significant improvement in formation and resorption markers and also failed to alter sclerostin concentrations between groups.

Assessment of Activity Profiles in Older Adults and Lower Limb Bone Parameters: Observations from the Hertfordshire Cohort Study

As muscle strength and function decline with age the optimal high-impact physical activity (PA) required for bone remodelling is rarely achievable in older adults. This study aimed to explore the activity profiles of community-dwelling older men and women and to assess the relationship between individual PA profiles and lower limb bone parameters. Participants from the Hertfordshire Cohort Study wore triaxial accelerometers for 7 days and counts of low (0.5-1.0 g), medium (1.0-1.5 g), and high (> 1.5 g) vertical-impact activity were calculated. Two years later, participants underwent a pQCT scan of the tibia (4% and 38% sites) to obtain measures of bone mineral density and bone geometry. Linear regression was used to quantify associations between bone and PA loading profiles adjusting for age, sex, loading category, and BMI. Results are presented as β [95% confidence interval]. Bone and PA data were available for 82 participants. The mean (SD) age at follow-up was 81.4(2.7) years, 41.5% (n = 34) were women. The median low-impact PA count was 5281 (Inter-quartile range (IQR) 2516-12,977), compared with a median of only 189 (IQR 54-593) in medium, and 39 (IQR 9-105) in high-impact counts. Positive associations between high-impact PA and cortical area (mm2), polar SSI (mm3), and total area (mm2) at the 38% slice (6.21 [0.88, 11.54]; 61.94 [25.73, 98.14]; 10.09 [3.18, 16.99], respectively). No significant associations were found at distal tibia. These data suggest that maintaining high (> 1.5 g)-impact activity is difficult for older adults to achieve; however, even small amounts of high-impact PA are positively associated with selected cortical bone parameters 2 years later.

A cross-sectional study of the relationship between recreational sporting activity and calcaneal bone density in adolescents and young adults

OBJECTIVE

Childhood and adolescence are critical periods of bone development. Sporting activity is thought to impact peak bone mass acquisition, but most studies have used dual-energy X-ray absorptiometry (DXA) to assess bone health and reported associations between bone mass and elite sporting activity. The objective of this study was instead to assess the relationship between recreational sporting activity (RSA) and another bone assessment, calcaneal quantitative ultrasound (cQUS), in adolescents and young adults.

METHODS

We related recreational sporting activity, assessed through a lifestyle questionnaire, to heel ultrasound bone parameters in a cohort of New Zealand students aged 16-35 years. Complete datasets with data on all relevant confounders (body mass index (BMI), pubertal timing, smoking status, and alcohol consumption) were available for 452 participants. cQUS was performed using a Lunar Achilles EX II machine to obtain bone parameters, broadband ultrasound attenuation (BUA), and speed of sound (SOS); stiffness index (SI) was derived from these measures. All descriptive statistics and statistical analyses were carried out using SPSS Statistics for Macintosh, Version 23.0 (IBM Corp., Armonk, NY, USA). Results are presented as p-values and 95% CI.

RESULTS

Reported lifetime sport participation declined after an individual's mid-teens. Bone cQUS parameters (SI and BUA and T-score) were all positively associated with BMI, and current physical activity (SI, SOS, BUA, T-score, and Z-score) with SI and SOS measures most strongly associated with current high impact and past recreational sporting activity (all p < 0.05).

CONCLUSION

Calcaneal heel ultrasound bone parameters were associated with physical activity, with SI and SOS rather than BUA more strongly related to current and past recreational sporting activity in young New Zealand adults.

Medical history, medication use and physical activity in adults in their eighth and ninth decade of life in the Hertfordshire Cohort Study

While there are many known health benefits to maintained physical activity levels in late adulthood, there have been very few studies that have considered relationships between morbidity profile and physical activity in the eighth decade of life. We studied 1097 participants, 555 men and 542 women from the Hertfordshire Cohort Study, a UK community based sample. Validated questionnaire based data were used to relate self-reported physical activity (PA) levels to medical history, and medication use. Regression analyses were adjusted for age, BMI, smoker status, alcohol consumption. The mean (SD) age of participants in the study was 80.2 (2.7) years for men and 80.2 (2.6) for women. A higher proportion of men (33.7 %) than women (24 %) were in the high activity score group. 20.8 % of female participants and 22.6 % male participants reported having no comorbid disease; 10.5 % men and 8.4 % women were taking no medication. Higher number of chronic conditions was associated with lower levels of PA [men (OR 0.73, 95 % CI 0.63-0.84, p<0.001); women (OR 0.74, 95 % CI 0.64-0.86, p<0.001)] as was being prescribed a higher number of medications [men (OR 0.88, 95 % CI 0.84-0.93, p<0.001); women (OR 0.86, 95 % CI 0.82-0.91, p<0.001)]. All these associations remained robust following adjustments. Strong relationships were seen in both sexes between PA and taking medication for disorders of the central nervous system and gastrointestinal system, with relationships generally stronger in men. We have observed relationships between comorbid medical history and medication use with physical activity in a cohort of community dwelling older adults. These highlight the need to consider medical history when considering how best to optimize PA in older adults.

Accelerometer-based osteogenic indices, moderate-to-vigorous and vigorous physical activity, and bone traits in adolescents

OBJECTIVES

We investigated the associations of accelerometry-derived osteogenic indices (OIs), moderate-to-vigorous (MVPA), and vigorous intensity physical activity (VPA) with peripheral quantitative computed tomography (pCQT) parameters in 99 adolescents aged 10-13 years.

METHODS

Bone parameters were assessed at the distal (4%) and shaft (66%) of the tibia using pQCT. Accelerometers were worn on the right hip for 7 consecutive days. OIs were calculated based on acceleration peak histograms either using all of the peaks (OI) or peaks with acceleration ≥5.2 g (HOI). MVPA and VPA were defined using previously published cut-points.

RESULTS

HOI was positively associated with total area (Partial correlation= 0.22, 95% CI=0.01 to 0.41), cortical area (CoA) (0.33, 95% CI=0.13 to 0.50), and stress strain index (SSI) (0.29, 95% CI=0.09 to 0.47) of tibial shaft and with total density at the distal tibia (0.23, 95% CI=0.02 to 0.42). OI was positively associated with CoA (0.31, 95% CI=0.11 to 0.49) and SSI (0.26, 95% CI=0.05 to 0.44) of tibial shaft. MVPA was positively associated with CoA (0.28, 95% CI=0.07 to 0.46) of the tibial shaft.

CONCLUSIONS

OI and HOI were positively associated with pQCT parameters while MVPA and VPA demonstrated less consistent associations with them.

Transmission of whole body vibration - Comparison of three vibration platforms in healthy subjects

The potential of whole body vibration (WBV) to maintain or enhance musculoskeletal strength during ageing is of increasing interest, with both low and high magnitude WBV having been shown to maintain or increase bone mineral density (BMD) at the lumbar spine and femoral neck. The aim of this study was to determine how a range of side alternating and vertical WBV platforms deliver vibration stimuli up through the human body. Motion capture data were collected for 6 healthy adult participants whilst standing on the Galileo 900, Powerplate Pro 5 and Juvent 100 WBV platforms. The side alternating Galileo 900 WBV platform delivered WBV at 5-30 Hz and amplitudes of 0-5 mm. The Powerplate Pro 5 vertical WBV platform delivered WBV at 25 and 30 Hz and amplitude settings of 'Low' and 'High'. The Juvent 1000 vertical WBV platform delivered a stimulus at a frequency between 32 and 37 Hz and amplitude 10 fold lower than either the Galileo or Powerplate, resulting in accelerations of 0.3 g. Motion capture data were recorded using an 8 camera Vicon Nexus system with 21 reflective markers placed at anatomical landmarks between the toe and the forehead. Vibration was expressed as vertical RMS accelerations along the z-axis which were calculated as the square root of the mean of the squared acceleration values in g. The Juvent 1000 did not deliver detectable vertical RMS accelerations above the knees. In contrast, the Powerplate Pro 5 and Galileo 900 delivered vertical RMS accelerations sufficiently to reach the femoral neck and lumbar spine. The maximum vertical RMS accelerations at the anterior superior iliac spine (ASIS) were 1.00 g ±0.30 and 0.85 g ±0.49 for the Powerplate and Galileo respectively. For similar accelerations at the ASIS, the Galileo achieved greater accelerations within the lower limbs, whilst the Powerplate recorded higher accelerations in the thoracic spine at T10. The Powerplate Pro 5 and Galileo 900 deliver vertical RMS accelerations sufficiently to reach the femoral neck and lumbar spine, whereas the Juvent 1000 did not deliver detectable vertical RMS accelerations above the knee. The side alternating Galileo 900 showed greater attenuation of the input accelerations than the vertical vibrations of the Powerplate Pro 5. The platforms differ markedly in the transmission of vibration with strong influences of frequency and amplitude. Researchers need to take account of the differences in transmission between platforms when designing and comparing trials of whole body vibration.

Associations of physical activity intensities, impact intensities and osteogenic index with proximal femur bone traits among sedentary older adults

BACKGROUND

Dynamic high-intensity physical activity is thought to be beneficial for older adults' bone health. Traditional volume-based processing of accelerometer-measured physical activity data, quantified on a minute-per-minute basis, may average out sporadic high impact activity, whereas accelerometer data processing approaches based on identifying impacts can capture also these potentially beneficial short activity bursts. We investigated the associations between habitual physical activity and proximal femur bone traits among sedentary older adults utilizing three different numerical treatments of accelerometer-data to examine, if impact-based processing approaches are more suitable to assess bone loading than volume-based processing of physical activity data among older adults.

METHODS

This cross-sectional study utilized the baseline data from the PASSWORD-study (n = 284, mean ± SD age 74 ± 4 years, 57% women). Total femur bone mineral content (BMC) and bone mineral density (BMD), femoral neck BMC, BMD, section modulus and minimal width (MNW) were measured with dual energy x-ray absorptiometry. Physical activity was measured for seven consecutive days with a tri-axial accelerometer. Raw acceleration data was processed in three different ways and quantified as i) mean daily minutes in sedentary, light and moderate-to-vigorous-intensity activity, ii) mean daily number of acceleration peaks divided into low (1.5 g to 2.0 g), medium (2.0 g to 2.5 g) and high (>2.5 g) impacts, and iii) mean daily osteogenic index, which is a summary score calculated from log-transformed number of impact peaks in 32 intensity bands (≥1.3 g). Associations between physical activity measures and each bone trait were estimated with multiple linear regression adjusted with covariates (age, sex, weight, height, smoking, physical function, medication).

RESULTS

Participants recorded on average 10 h sedentary, 2.5 h light and 33 min moderate-to-vigorous activity, and 3937 low, 494 medium and 157 high impacts per day. Mean osteogenic index score was 173. Light physical activity was positively associated with all bone traits (beta = 0.147 to 0.182, p < 0.001 to p = 0.005) except MNW. Sedentary or moderate-to-vigorous activity, low, medium or high impacts or osteogenic index were not associated with any bone parameter.

CONCLUSIONS

Light physical activity may decelerate the age-related bone loss in older adults who do not meet the physical activity recommendations. In this population, the amount of high impact activity may be insufficient to stimulate bone remodelling.

Physical Activity Throughout Adolescence and Peak Hip Strength in Young Adults

IMPORTANCE

Peak bone strength, which occurs in early adulthood, is an important marker of the future risk of osteoporosis. It is therefore important to identify modifiable early life factors that are associated with the attainment of peak hip strength.

OBJECTIVE

To investigate the association of time spent in moderate to vigorous-intensity and light-intensity physical activity throughout adolescence with peak hip strength in adulthood.

DESIGN, SETTING, AND PARTICIPANTS

The Avon Longitudinal Study of Parents and Children is a prospective birth cohort study that initially recruited all pregnant women residing within the catchment area of 3 health authorities in southwest England who had an expected delivery date between April 1, 1991, and December 31, 1992. In total, 15 454 eligible pregnant women were enrolled, and 15 589 infants were delivered. Of those, 14 901 infants were alive at age 1 year. The present analysis examined 2569 healthy offspring who had valid physical activity measurements obtained during a clinical assessment for at least 1 age (12, 14, 16, and/or 25 years), with up to 4 repeated accelerometer assessments performed (1 per age-associated clinical visit). Data were analyzed from June 2019 to June 2020.

EXPOSURES

Trajectories of accelerometer-assessed time spent in moderate to vigorous-intensity and light-intensity physical activity at ages 12, 14, 16, and 25 years (measured in minutes per day) were identified using latent trajectory modeling. Moderate to vigorous-intensity and light-intensity physical activity were determined using established thresholds of acceleration counts per minute.

MAIN OUTCOMES AND MEASURES

Femur neck bone mineral density (BMD; measured in g/cm2) at age 25 years assessed by dual-energy radiography absorptiometry scans of the hip.

RESULTS

A total of 2569 participants (1588 female participants [62%]) were included in the analysis. Male participants spent more time in moderate to vigorous-intensity activity at each age and had greater adult femur neck BMD than female participants. For each sex, 3 moderate to vigorous-intensity trajectory subgroups and 3 light-intensity trajectory subgroups were identified. With regard to the moderate to vigorous-intensity trajectories, most male participants (85%) were in the low adolescent subgroup, with only 6% and 9% in the high early-adolescent and high mid-adolescent subgroups, respectively. Moderate to vigorous-intensity trajectories in female participants were divided into low adolescent-low adult (73%), low adolescent-high adult (8%), and high adolescent (19%) subgroups. Light-intensity physical activity trajectories were classified into low nonlinear, moderate decreasing, and high decreasing subgroups for both sexes. Femur neck BMD in male participants was greater in the high early-adolescent subgroup (0.38 g/cm2; 95% CI, 0.11-0.66 g/cm2) and the high mid-adolescent subgroup (0.33 g/cm2; 95% CI, 0.07-0.60 g/cm2) compared with the low adolescent (reference) subgroup. Femur neck BMD in female participants was greater in the high adolescent subgroup (0.28 g/cm2; 95% CI, 0.15-0.41 g/cm2) but not in the low adolescent-high adult subgroup (-0.12 g/cm2; 95% CI, -0.44 to 0.20 g/cm2) compared with the low adolescent-low adult (reference) subgroup. A sensitivity analysis using a negative-outcome control variable to explore unmeasured confounding supported these findings. The light-intensity trajectories were not associated with femur neck BMD; for example, differences in femur neck BMD between the high decreasing and low nonlinear subgroups were 0.16 g/cm2 (95% CI, -0.08 to 0.40 g/cm2) in male participants and 0.20 g/cm2 (95% CI, -0.05 to 0.44 g/cm2) in female participants.

CONCLUSIONS AND RELEVANCE

Supporting high-intensity physical activity throughout early life may help to maximize peak hip strength and prevent osteoporosis in later life. Replication of our findings in independent studies will be important.

Targeted genotype analyses of GWAS-derived lean body mass and handgrip strength-associated single-nucleotide polymorphisms in elite master athletes

Recent large genome-wide association studies (GWAS) have independently identified a set of genetic loci associated with lean body mass (LBM) and handgrip strength (HGS). Evaluation of these candidate single-nucleotide polymorphisms (SNPs) may be useful to investigate genetic traits of populations at higher or lower risk of muscle dysfunction. As such, we investigated associations between six SNPs linked to LBM or HGS in a population of elite master athletes (MA) and age-matched controls as a representative population of older individuals with variable maintenance of muscle mass and function. Genomic DNA was isolated from buffy coat samples of 96 individuals [consisting of 48 MA (71 ± 6 yr, age-graded performance 83 ± 9%) and 48 older controls (75 ± 6 yr)]. SNP validation and sample genotyping were conducted using the tetra-primer amplification refractory mutation system (ARMS). For the three SNPs analyzed that were previously associated with LBM (FTO, IRS1, and ADAMTSL3), multinomial logistic regression revealed a significant association of the ADAMTSL3 genotype with %LBM (P < 0.01). For the three HGS-linked SNPs, neither GBF1 nor GLIS1 showed any association with HGS, but for TGFA, multinomial logistic regression revealed a significant association of genotype with HGS (P < 0.05). For ADAMTSL3, there was an enrichment of the effect allele in the MA (P < 0.05, Fisher's exact test). Collectively, of the six SNPs analyzed, ADAMTSL3 and TGFA showed significant associations with LBM and HGS, respectively. The functional relevance of the ADAMTSL3 SNP in body composition and of TGFA in strength may highlight a genetic component of the elite MA phenotype.

Correlates of high-impact physical activity measured objectively in older British adults

Background

Exposure to higher magnitude vertical impacts is thought to benefit bone health. The correlates of this high-impact physical activity (PA) in later life are unknown.

Methods

Participants were from the Cohort for Skeletal Health in Bristol and Avon, Hertfordshire Cohort Study and MRC National Survey of Health and Development. Associations of demographic, behavioural, physiological and psychological factors with vertical acceleration peaks ≥1.5 g (i.e. high-impact PA) from 7-day hip-worn accelerometer recordings were examined using linear regression.

Results

A total of 1187 participants (mean age = 72.7 years, 66.6% females) were included. Age, sex, education, active transport, self-reported higher impact PA, walking speed and self-rated health were independently associated with high-impact PA whereas BMI and sleep quality showed borderline independent associations. For example, differences in log-high-impact counts were 0.50 (P < 0.001) for men versus women and −0.56 (P < 0.001) for worst versus best self-rated health. Our final model explained 23% of between-participant variance in high impacts. Other correlates were not associated with high-impact activity after adjustment.

Conclusions

Besides age and sex, several factors were associated with higher impact PA in later life. Our findings help identify characteristics of older people that might benefit from interventions designed to promote osteogenic PA.

Comparison of Muscle Function, Bone Mineral Density and Body Composition of Early Starting and Later Starting Older Masters Athletes

Masters endurance runners can epitomize healthy aging; being reflective of the physiological processes of aging without the compounded effects of inactivity. The primary aim of the present study was to determine, using cross-sectional data, whether individuals taking up training after the age of 50 years can achieve the same level of athletic performance and musculoskeletal characteristics in their older age as those who trained all of their adult lives. A total of 150 master endurance runners [age 68 (5) years; 111 male, 39 female] were divided into early starters (training all of their adulthood) and late starters (started training after age 50 years). A comparative non-athletic group of 59 healthy older adults [age 73 (4) years; 30 female, 29 male] were additionally included for analysis. Training intensity, age-graded performance (AGP) and musculoskeletal assessments were performed. Results showed that there was no difference between athlete groups for training intensity or age-graded performance, despite the 30-year difference in training history. Body fat percentage and leg lean mass did not differ between athlete groups, but were 17% lower and 12% greater, respectively, in athlete groups compared with controls. Power normalized to body mass did not differ between any groups. Spine BMD was lower in late starters than controls, while early starters did not differ from late starters or controls. Hip BMD did not differ between any of the groups. These findings show that the Masters athletes we studied that started intense endurance running after the age of 50 years had lower body fat and higher leg lean mass compared to non-athletes. Body composition and athletic performance of the late starters was very similar to those who trained all of their adult lives.

Day-to-day physical activity producing low gravitational impacts is associated with faster visual processing speed at age 69: cross-sectional study

BACKGROUND

Little is known about how different physical activity (PA) parameters relate to cognitive function in older adults. Using accelerometers calibrated to detect vertical impacts from ground reaction forces we examined the associations of low, medium and higher impact PA with processing speed, verbal memory and cognitive state in older adults.

METHODS

Participants were 69-year old British men and women from the Medical Research Council National Survey of Health and Development included in a vertical impacts and bone sub-study (n = 558; 48.2% female). Counts of low (0.5 < g < 1.0 g), medium (1 < g < 1.5 g), or higher (≥1.5 g) magnitude impacts were derived from vertical acceleration peaks recorded over 7 days by hip-worn accelerometers. Processing speed was assessed by a timed visual letter search task, verbal memory by a 15-word list learning test and cognitive state by the Addenbrooke's Cognitive Examination (ACE-III). Potential confounders were childhood cognitive ability, adult socioeconomic position, body mass index and depression.

RESULTS

In initial sex-adjusted models, low magnitude impacts were associated with better performance in all three cognitive function tests; standard deviation differences in test scores per doubling in number of low impacts: letter search speed = 0.10 (95% confidence intervals (CI): 0.03 to 0.16), word learning test = 0.05 (95% CI: 0.00 to 0.11), ACE-III scale = 0.09 (95% CI: 0.03 to 0.14). After adjustment for confounders, differences persisted for letter search speed (0.09; 95% CI: 0.02 to 0.16) but were closer to the null for the word learning test (0.02; 95% CI: - 0.04 to 0.07) and ACE-III scores (0.04; 95% CI: - 0.01 to 0.09). Low impacts remained associated with letter search speed after sensitivity analyses excluding those with functional and musculoskeletal problems, and after adjustment for impacts in higher bands. Modest positive associations between higher magnitude impacts and cognitive test scores were most likely due to chance.

CONCLUSION

Accelerometer-derived low impact physical activity was associated with better visual processing speed in 69-year old men and women independently of childhood cognitive ability and other measured confounders. Day-to-day low impact physical activity may therefore have the potential to benefit cognitive health in older adults.

Sarcopenia Is Negatively Related to High Gravitational Impacts Achieved From Day-to-day Physical Activity

Background

Sarcopenia has been associated with reduced physical activity (PA). We aimed to determine if sarcopenia, and specific components of muscle size, function, and physical performance, are associated with high impacts achieved during habitual PA, as these are related to bone strength in community-dwelling older women.

Methods

Participants were older women from the Cohort of Skeletal Health in Bristol and Avon. We defined sarcopenia using the EWGSOP criteria. Lower limb peak muscle power and force were assessed using Jumping Mechanography (JM). High vertical impacts were assessed by tri-axial accelerometry (at least 1.5g above gravity). Cross-sectional associations were analyzed by linear regression, adjusting for age, height and weight (or fat mass for models including appendicular lean mass index), comorbidities, smoking, alcohol, and Index of Multiple Deprivation.

Results

Our analyses included 380 participants, with mean age 76.7 (SD 3.0) years; 242 (64%) also completed JM. In age-adjusted analysis, a negative relationship was observed between severity of sarcopenia and high, but not medium or low, impacts (p = .03 for trend). Regarding components of sarcopenia underlying this relationship, multivariable analyses revealed that gait speed (β 1.47 [95% CI 1.14, 1.89], [β-1] reflects the proportionate increase in high impacts per SD increase in exposure) and peak force (1.40 [1.07, 1.84]) were independently associated with high impacts.

Conclusions

Older women with sarcopenia experienced fewer bone-strengthening high impacts than those with presarcopenia or without sarcopenia. To increase bone strengthening activity in older women, interventions need to improve both lower limb muscle force and walking speed.

A diagnosis of knee osteoarthritis does not predict physical activity 2 years later in older adults: findings from the Hertfordshire Cohort Study

Osteoarthritis (OA) can negatively impact levels of physical activity (PA), although current clinical advice promotes the benefits of staying active in preventing joint degeneration. In this study, we examine how knee OA, assessed by self-report, clinical assessment and radiographic assessment, impacts upon objectively measured PA 2 years later. The study population is comprised of 114 subjects from the Hertfordshire Cohort Study (HCS). The presence of OA at the knee was determined from self-report, and clinical and radiological examination, defined according to American College of Rheumatology (ACR) criteria and Kellgren and Lawrence grading system. Two years later, Gulf Coast Data Concepts (GCDC) tri-axial accelerometers were used to measure day-to-day levels of PA. Vertical acceleration peaks over 7 days, expressed in g units, were categorised into low (0.5 ≤ g < 1.0), medium (1.0 ≤ g < 1.5) and high (≥ 1.5 g) impacts. The study comprises 69 men and 45 women. The mean (SD) age was 78.5 (2.6) for men and 78.6 (2.7) for women. Low count numbers were recorded in the medium and high impact bands. We found no significant reduction in low, medium or high impacts in individuals who had been previously diagnosed with self-reported, radiographic or clinical knee OA in this sample after adjustment for age, sex and BMI. In our cohort, participants with knee OA were no less likely to partake in objectively measured weight-bearing activity 2 years after assessment than counterparts without a diagnosis of knee OA.

Influence of Habitual Physical Behavior - Sleeping, Sedentarism, Physical Activity - On Bone Health in Community-Dwelling Older People

Sedentary behavior (SB) has emerged as an independent public-health risk and may contribute to the lower bone mineral density (BMD) in old (>60 years of age) than young adults. The purpose of this study was to quantify SB and habitual physical behavior (PB) in community-dwelling older adults and how this correlates with BMD. In 112 relatively healthy and independent-living individuals aged 72.5 ± 6.4 years, BMD, PB and SB were determined using dual energy X-ray absorptiometry and 7-day three-dimensional accelerometry, respectively. In men, only healthy and osteopenic BMDs were found, whereas in women, osteoporotic BMD classifications also occurred. Our sample spent ∼61%, 7%, 12% and 19% of daily waking hours in SB, standing, LIPA [light intensity physical activity (PA)] and MVPA (medium-to-vigorous intensity PA), respectively. In men, after accounting for covariates (BMI, total fat, android:gynoid ratio), sleeping (hours/day), number of breaks in SB, number of SB ≥ 5 min, number of PA bouts, total duration of PA bouts (min), mean PA bouts duration (min), LIPA (%PA bout time) and MVPA (%PA bout time) were all predictors of BMD. In women, after accounting for covariates (age, BMI, total fat, android:gynoid ratio), SB (hours/day), SB (% waking hours), LIPA (hours/day), LIPA (% waking hours), MVPA (% waking hours) and number of short SB (i.e., <5 min), total time spent in PA (min) significantly correlated with BMD. In conclusion, the PB predictors of bone health in older persons include: night time sleeping duration, number of short bouts of SB, number and duration of bouts of PA relative to total waking hours. While radar graphs of PB patterns for healthy, osteopenic, osteoporotic individuals highlighted significant differences in PB between them, they were not consistent with the expectations from the Mechanostat Theory: i.e., more loading leads to better bone. Rather, our results suggest that a balance of activities must be maintained across the PB spectrum, where certain PB parameters are especially impactful in each sex, supporting the recently coined multifactorial-based variations in the Mechanostat threshold.

Physical Activity and Bone Accretion: Isotemporal Modeling and Genetic Interactions

PURPOSE

This study aimed to determine if replacing time spent in high- and low-impact physical activity (PA) predicts changes in pediatric bone mineral density (BMD) and content (BMC).

METHODS

We analyzed data from the longitudinal Bone Mineral Density in Childhood Study (N = 2337 with up to seven visits). The participants were age 5-19 yr at baseline, 51.2% were female, and 80.6% were nonblack. Spine, total hip, and femoral neck areal BMD and total body less head (TBLH) BMC Z-scores were calculated. Hours per day spent in high- and low-impact PA were self-reported. Standard covariate-adjusted (partition model) and time allocation-sensitive isotemporal substitution modeling frameworks were applied to linear mixed models. Statistical interactions with sex, self-reported ancestry, age, and bone fragility genetic scores (percentage of areal BMD-lowering alleles carried) were tested.

RESULTS

In standard models, high-impact PA was positively associated with bone Z-score at all four skeletal sites (e.g., TBLH-BMC Z-score: beta = 0.05, P = 2.0 × 10), whereas low-impact PA was not associated with any of the bone Z-scores. In isotemporal substitution models, replacing 1 h·d of low- for high-impact PA was associated with higher bone Z-scores (e.g., TBLH-BMC Z-score: beta = 0.06, P = 2.9 × 10). Conversely, replacing 1 h·d of high- for low-impact PA was associated with lower bone Z-scores (e.g., TBLH-BMC Z-score: beta = -0.06, P = 2.9 × 10). The substitution associations were similar for each sex and ancestry group, and for those with higher and lower genetic scores for bone fragility (P-interactions > 0.05), but increased in strength among the older adolescents (P-age interactions < 0.05).

CONCLUSIONS

Time-sensitive models suggest that replacing low-impact PA for high-impact PA would be beneficial for the growing skeleton in the majority of children.

The relationship between objectively assessed physical activity and bone health in older adults differs by sex and is mediated by lean mass

Relationships between objectively assessed free-living physical activity (PA) and changes in bone health over time are poorly understood in older adults. This study suggests these relationships are sex-specific and that body composition may influence the mechanical loading benefits of PA.

INTRODUCTION

To investigate associations of objectively assessed PA and bone health in community-dwelling older adults.

METHODS

This secondary analysis of a subset of the Tasmanian Older Adult Cohort study included participants with PA assessed utilising ActiGraph GT1M accelerometers over 7 days (N = 209 participants, 53% female; mean ± SD age 64.5 ± 7.2 years). Steps/day and PA intensity were estimated via established thresholds. Bone mineral content (BMC) was acquired at the total hip, lumbar spine, legs and whole body by DXA at baseline and approximately 2.2 years later. Relationships between PA and BMC were assessed by multivariable linear regression analyses adjusted for age, smoking status, height and total lean mass.

RESULTS

Men with above-median total hip BMC completed significantly less steps per day, but there was no significant difference in PA intensity compared with those with below-median BMC. There were no significant differences in PA in women stratified by median BMC. In women, steps/day were positively associated with leg BMC (B = 0.178; P = 0.017), and sedentary behaviour was negatively associated with leg BMC (- 0.165; 0.016) at baseline. After adjustment for confounders including lean mass and height, higher sedentary behaviour at baseline was associated with declines in femoral neck BMC (- 0.286; 0.011) but also with increases in pelvic BMC (0.246; 0.030) in men and increases in total hip BMC (0.215; 0.032) in women, over 2.2 years. No other significant longitudinal associations were observed after adjustment for body composition.

CONCLUSIONS

Associations of accelerometer-determined sedentary behaviour and PA with bone health in older adults differ by sex and anatomical site and are mediated by body composition.

Physical Activity Producing Low, but Not Medium or Higher, Vertical Impacts Is Inversely Related to BMI in Older Adults: Findings From a Multicohort Study

Background

High impact physical activity (PA) is thought to improve skeletal health, but its relation to other health outcomes are unclear. We investigated associations between PA impact magnitude and body mass index (BMI) in older adults.

Methods

Data were taken from the Cohort for Skeletal Health in Bristol and Avon (COSHIBA), Hertfordshire Cohort Study, and MRC National Survey of Health and Development. Vertical acceleration peaks from 7-day hip-worn accelerometer recordings were used to classify PA as low (0.5 < g < 1.0g), medium (1 < g < 1.5g), or higher (≥1.5g) impact. Cohort-specific associations of low, medium, and higher impact PA with BMI were examined using linear regressions and estimates combined using random-effects meta-analysis.

Results

A total of 1182 participants (mean age = 72.7 years, 68% female) were included. Low, medium, and higher impact PA were inversely related to BMI in initial models. After adjustment for confounders and other impacts, low, but not medium or higher, impacts were inversely related to BMI (-0.31, p < .001: overall combined standard deviation change in BMI per doubling in the number of low impacts). In adjusted analyses of body composition measured by dual-energy X-ray absorptiometry in COSHIBA, low, but not medium or higher, impacts were inversely related to total body fat mass (-0.19, p < .001) and android:gynoid fat mass ratio (-0.16, p = .01), whereas high impact PA was weakly and positively associated with lean mass (0.05, p = .06).

Conclusions

Greater exposure to PA producing low magnitude vertical impacts was associated with lower BMI and fat mass at older age. Low impact PA may help reduce obesity risk in older adults.

Hip and spine bone mineral density are greater in master sprinters, but not endurance runners compared with non-athletic controls

We examined bone density in older athletes and controls. Sprinters had greater hip and spine bone density than endurance athletes and controls, whereas values were similar in the latter two groups. These results could not be explained by differences in impact, muscle size or power between sprint and endurance athletes.

PURPOSE

We examined the relationship between prolonged participation in regular sprint or endurance running and skeletal health at key clinical sites in older age, and the factors responsible for any associations which we observed.

METHODS

We recruited 38 master sprint runners (28 males, 10 females, mean age 71 ± 7 years), 149 master endurance runners (111 males, 38 females, mean age 70 ± 6 years) and 59 non-athletic controls (29 males, 30 females, mean age 74 ± 5 years). Dual X-ray absorptiometry was used to assess hip and spine bone mineral density (BMD), body composition (lean and fat mass), whilst jump power was assessed with jumping mechanography. In athletes, vertical impacts were recorded over 7 days from a waist-worn accelerometer, and details of starting age, age-graded performance and training hours were recorded.

RESULTS

In ANOVA models adjusted for sex, age, height, body composition, and jump power, sprinter hip BMD was 10 and 14% greater than that of endurance runners and controls respectively. Sprinter spine BMD was also greater than that of both endurance runners and controls. There were no differences in hip or spine BMD between endurance runners and controls. Stepwise regression showed only discipline (sprint/endurance), sex, and age as predictors of athlete spine BMD, whilst these variables and starting age were predictive of hip BMD.

CONCLUSIONS

Regular running is associated with greater BMD at the fracture-prone hip and spine sites in master sprinters but not endurance runners. These benefits cannot be explained by indicators of mechanical loading measured in this study including vertical impacts, body composition or muscular output.

A small amount of precisely measured high-intensity habitual physical activity predicts bone health in pre- and post-menopausal women in UK Biobank

Background

Physical inactivity is a highly modifiable risk factor for the development of osteoporosis but, due to a lack of research that has precisely and objectively meaured physical activity (PA) relevant to bone, the specific contribution that PA can make to bone health is poorly understood. This study examined whether a more precise measure of PA relelvant to bone was associated with meaures of bone health in pre- and post-menopausal women in UK Biobank.

Methods

Time spent at intensities specific to bone health [≥750 milli-gravitational units (mg) and ≥1000 mg] were analysed from raw tri-axial acceleration data averaged over 1-second epochs from 7-day monitoring of habitual PA using accelerometry-based activity monitors (100 Hz; AX3, Axivity, UK) of 1218 pre- and 1316 post-menopausal healthy women. In a cross-sectional analysis, associations between categories of time (<1, 1-2 and ≥2 minutes) spent above the intensity thresholds and calcaneal quantitative ultrasound measures of bone health (bone mineral density T-score, BMDT-score; speed of sound, SOS; and broadband ultrasound attenuation, BUA) were examined.

Results

Compared with <1 minute, spending 1-2 or ≥2 minutes/day at intensities ≥1000 mg in pre-menopausal and ≥750 mg in post-menopausal women was positively associated with BMDT-score, SOS and BUA.

Conclusion

Brief bursts of high-intensity PA relevant to bone health can be captured by applying bone-specific thresholds of intensity to raw tri-axial accelerations averaged over 1-second epochs. Accumulating 1-2 minutes/day of high-intensity PA, equivalent to running in pre-menopausal women and slow jogging in post-menopausal women, is associated with better bone health.

Associations of lifetime walking and weight bearing exercise with accelerometer-measured high impact physical activity in later life

High impact physical activity (PA) is thought to benefit bone. We examined associations of lifetime walking and weight bearing exercise with accelerometer-measured high impact and overall PA in later life. Data were from 848 participants (66.2% female, mean age = 72.4 years) from the Cohort for Skeletal Health in Bristol and Avon, Hertfordshire Cohort Study and MRC National Survey of Health and Development. Acceleration peaks from seven-day hip-worn accelerometer recordings were used to derive counts of high impact and overall PA. Walking and weight bearing exercise up to age 18, between 18-29, 30-49 and since age 50 were recalled using questionnaires. Responses in each age category were dichotomised and cumulative scores derived. Linear regression was used for analysis. Greater lifetime walking was related to higher overall, but not high impact PA, whereas greater lifetime weight bearing exercise was related to higher overall and high impact PA. For example, fully-adjusted differences in log-overall and log-high impact PA respectively for highest versus lowest lifetime scores were: walking [0.224 (0.087, 0.362) and 0.239 (- 0.058, 0.536)], and weight bearing exercise [0.754 (0.432, 1.076) and 0.587 (0.270, 0.904)]. For both walking and weight bearing exercise, associations were strongest in the 'since age 50' category. Those reporting the most walking and weight bearing exercise since age 50 had highest overall and high impact PA, e.g. fully-adjusted difference in log-high impact PA versus least walking and weight bearing exercise = 0.588 (0.226, 0.951). Promoting walking and weight bearing exercise from midlife may help increase potentially osteogenic PA levels in later life.

Prescribing Physical Activity for the Prevention and Treatment of Osteoporosis in Older Adults

Osteoporosis is an age-related disease, characterised by low bone mineral density (BMD) and compromised bone geometry and microarchitecture, leading to reduced bone strength. Physical activity (PA) has potential as a therapy for osteoporosis, yet different modalities of PA have varying influences on bone health. This review explores current evidence for the benefits of PA, and targeted exercise regimes for the prevention and treatment of osteoporosis in older adults. In particular, the outcomes of interventions involving resistance training, low- and high-impact weight bearing activities, and whole-body vibration therapy are discussed. Finally, we present recommendations for future research that may maximise the potential of exercise in primary and secondary prevention of osteoporosis in the ageing population.

Habitual levels of higher, but not medium or low, impact physical activity are positively related to lower limb bone strength in older women: findings from a population-based study using accelerometers to classify impact magnitude

This study assessed the effect of accelerometry-measured higher impacts resulting from habitual weight-bearing activity on lower limb bone strength in older women. Despite higher impacts being experienced rarely in this population-based cohort, positive associations were observed between higher vertical impacts and lower limb bone size and strength.

INTRODUCTION

We investigated whether the benefit of habitual weight-bearing physical activity (PA) for lower limb bone strength in older women is explained by exposure to higher impacts, as previously suggested by observations in younger individuals.

METHODS

Four hundred and eight women from the Cohort for Skeletal Health in Bristol and Avon (COSHIBA), mean 76.8 years, wore tri-axial accelerometers at the waist for a mean of 5.4 days. Y-axis peaks were categorised, using previously identified cutoffs, as low (0.5-1.0 g), medium (1.0-1.5 g), and higher (≥1.5 g) impacts. Mid and distal peripheral quantitative computed tomography scans of the tibia and radius were performed, as were hip and lumbar spine Dual X-ray Absorptiometry (DXA) scans. Regressions between (log transformed) number of low, medium and high impacts, and bone outcomes were adjusted for artefact error grade, age, height, fat and lean mass and impacts in other bands.

RESULTS

Eight thousand eight hundred and nine (4047, 16,882) low impacts were observed during the measurement week, 345 (99, 764) medium impacts and 42 (17, 106) higher impacts (median with 25th and 75th quartiles). Higher vertical impacts were positively associated with lower limb bone strength as reflected by cross-sectional moment of inertia (CSMI) of the tibia [0.042 (0.012, 0.072) p = 0.01] and hip [0.067 (0.001, 0.133) p = 0.045] (beta coefficients show standard deviations change per doubling in impacts, with 95 % confidence interval). Higher impacts were positively associated with tibial periosteal circumference (PC) [0.015 (0.003, 0.027) p = 0.02], but unrelated to hip BMD. Equivalent positive associations were not seen for low or medium impacts.

CONCLUSIONS

Despite their rarity, habitual levels of higher impacts were positively associated with lower limb bone size and strength, whereas equivalent relationships were not seen for low or medium impacts.

Feasibility and acceptability of using jumping mechanography to detect early components of sarcopenia in community-dwelling older women

OBJECTIVE

To determine the feasibility and acceptability of using peak power and force, measured by jumping mechanography (JM), to detect early age-related features of sarcopenia in older women.

METHODS

Community-dwelling women aged 71-87 years were recruited into this cross-sectional study. Physical function tests comprised the short physical performance battery (SPPB), grip strength and, if SPPB score≥6, JM. JM measured peak weight-adjusted power and force from two-footed jumps and one-legged hops respectively. Questionnaires assessed acceptability.

RESULTS

463 women were recruited; 37(8%) with SPPB⟨6 were ineligible for JM. Of 426 remaining, 359(84%) were able to perform ≥1 valid two-footed jump, 300(70%) completed ≥1 valid one-legged hop. No adverse events occurred. Only 14% reported discomfort. Discomfort related to JM performance, with inverse associations with both power and force (p⟨0.01). Peak power and force respectively explained 8% and 10% of variance in SPPB score (13% combined); only peak power explained additional variance in grip strength (17%).

CONCLUSIONS

Peak power and force explained a significant, but limited, proportion of variance in SPPB and grip strength. JM represents a safe and acceptable clinical tool for evaluating lower-limb muscle power and force in older women, detecting distinct components of muscle function, and possibly sarcopenia, compared to those evaluated by more established measures.

Socio-economic factors influencing the development of end-stage renal disease in people with Type 1 diabetes - a longitudinal population study

AIMS

The development of end-stage renal disease (ESRD) in Type 1 diabetes is multifactorial. Familial socio-economic factors may influence adherence to and understanding of diabetes treatment, and also general health behaviour. We investigate how parental and personal education level and exposure to low economic status, indicated by the need for income support, influence the development of ERSD caused by Type 1 diabetes.

METHODS

Participants were retrieved from the nationwide Swedish Childhood Diabetes Registry, which was linked to the Swedish Renal Registry, to find people with ESRD caused by Type 1 diabetes, and to Statistic Sweden to retrieve longitudinal socio-economic data on participants and their parents. Data were analysed using Cox regression modelling.

RESULTS

Of 9287 people with diabetes of duration longer than 14 years, 154 had developed ESRD due to diabetes. Median diabetes duration (range) for all participants was 24.2 years (14.0-36.7 years). Low maternal education (≤ 12 years) more than doubled the risk of developing ESRD, hazard ration (HR) = 2.9 [95% confidence interval (95% CI): 1.7-4.8]. For people with a low personal level of education HR was 5.7 (3.4-9.5). In an adjusted model, the person's own education level had the highest impact on the risk of ESRD. If at least one of the parents had ever received income support the HR was 2.6 (1.9-3.6).

CONCLUSIONS

Socio-economic factors, both for the parents and the person with diabetes, have a strong influence on the development of ESRD in Type 1 diabetes. It is important for caregivers to give enough support to more vulnerable people and their families.

A novel accelerometer-based method to describe day-to-day exposure to potentially osteogenic vertical impacts in older adults: findings from a multi-cohort study

This observational study assessed vertical impacts experienced in older adults as part of their day-to-day physical activity using accelerometry and questionnaire data. Population-based older adults experienced very limited high-impact activity. The accelerometry method utilised appeared to be valid based on comparisons between different cohorts and with self-reported activity.

INTRODUCTION

We aimed to validate a novel method for evaluating day-to-day higher impact weight-bearing physical activity (PA) in older adults, thought to be important in protecting against osteoporosis, by comparing results between four cohorts varying in age and activity levels, and with self-reported PA levels.

METHODS

Participants were from three population-based cohorts, MRC National Survey of Health and Development (NSHD), Hertfordshire Cohort Study (HCS) and Cohort for Skeletal Health in Bristol and Avon (COSHIBA), and the Master Athlete Cohort (MAC). Y-axis peaks (reflecting the vertical when an individual is upright) from a triaxial accelerometer (sampling frequency 50 Hz, range 0-16 g) worn at the waist for 7 days were classified as low (0.5-1.0 g), medium (1.0-1.5 g) or higher (≥1.5 g) impacts.

RESULTS

There were a median of 90, 41 and 39 higher impacts/week in NSHD (age 69.5), COSHIBA (age 76.8) and HCS (age 78.5) participants, respectively (total n = 1512). In contrast, MAC participants (age 68.5) had a median of 14,322 higher impacts/week. In the three population cohorts combined, based on comparison of beta coefficients, moderate-high-impact activities as assessed by PA questionnaire were suggestive of stronger association with higher impacts from accelerometers (0.25 [0.17, 0.34]), compared with medium (0.18 [0.09, 0.27]) and low impacts (0.13 [0.07,0.19]) (beta coefficient, with 95 % CI). Likewise in MAC, reported moderate-high-impact activities showed a stronger association with higher impacts (0.26 [0.14, 0.37]), compared with medium (0.14 [0.05, 0.22]) and low impacts (0.03 [-0.02, 0.08]).

CONCLUSIONS

Our new accelerometer method appears to provide valid measures of higher vertical impacts in older adults. Results obtained from the three population-based cohorts indicate that older adults generally experience very limited higher impact weight-bearing PA.