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

Abstract

SummaryThis 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.IntroductionWe 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.MethodsParticipants 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.ResultsThere 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]).ConclusionsOur 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.Electronic supplementary materialThe online version of this article (doi:10.1007/s00198-016-3810-5) contains supplementary material, which is available to authorized users.

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

“…Our findings may also be susceptible to survival bias which would underestimate associations as those healthiest and most active survive to old age, possibly because of lower debilitating illness and greater maintenance of physical function allowing continued participation in PA. Likewise, our findings may have been influenced by inclusion of participants who are more aware of the benefits of PA and keep a more active lifestyle than the general population, particularly as VIBE participants tended to have lower BMI and higher educational level compared with other participants from the three contributing studies who did not participate in VIBE ( Hannam et al, 2016b ).…”

“…Our findings suggest that continued participation in both walking and weight bearing exercise may be important for both overall and higher impact PA in older age. To this end, supporting both walking and weight bearing exercises, including activities like tennis and dancing ( Hannam et al, 2016b ), from midlife may be important for an active and functional older life including better skeletal health by promoting both overall and higher impact PA in later life. In addition, aerobics classes may provide a safe way for older adults to achieve exposure to higher impacts ( Hannam et al, 2016c ).…”

“…We defined high impact PA as vertical acceleration peaks ≥ 1.5 g, where g values represent g over and above 1 g from earth's gravitational force, and was previously validated in older adults attending an exercise class ( Hannam et al, 2016c ). The ≥ 1.5 g cut-point for higher impacts was selected as very few impacts were observed within higher g bands ( Deere et al, 2016 , Hannam et al, 2016a , Hannam et al, 2016b ). In addition, we derived a measure of overall PA by summing the total number of low, medium and higher magnitude acceleration peaks from all (i.e.…”

“…(e.g. running, racquet sports, football, rugby, hockey and dancing – not including walking, cycling or swimming), which are activities that have been shown to produce higher impacts ( Hannam et al, 2016c , Hannam et al, 2016b ). Possible responses were none, occasionally (once a month), frequently (once a week) or very frequently (more than once a week).…”

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

“…Epidemiological studies have traditionally relied upon the use of health questionnaires, thus not providing an objective measure of PA as brief, non-volitional periods of activity will likely be excluded [5]. Accelerometer-based PA readings have been developed as part of the Vertical Impacts on Bone in the Elderly (VIBE) study (a novel method for evaluating day-today vertical impacts from weight-bearing PA, subsequently classified according to impact magnitude) [6]. Vertical accelerations reflect impacts resulting from weight-bearing activity to which the skeleton preferentially responds.…”