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Table 6 The relationship between physical activity and bone and skeletal health

From: Systematic review of the relationships between physical activity and health indicators in the early years (0-4 years)

# of studies

Design

Quality assessment

# of participants

Absolute effect

Quality

Risk of bias

Inconsistency

Indirectness

Imprecision

Other

Mean baseline age ranged from 9.27-57.12 months. One study reported the baseline age as 6 months but a mean was not given. Data were collected by RCT and cross-sectional study designs. Several bone and skeletal health measures were assessed by X-ray absorptiometry including: total bone mineral content, bone mineral density of the lumbar spine (L2-L4), total body bone area, periosteal circumference of tibia, endosteal circumference of tibia, cortical bone area of tibia, hip bone area, hip bone mineral content, areal bone mineral density, and estimated volumetric bone mineral density. Bone and skeletal health was also assessed by vitamin D (25-(OH)- vitamin D3 measured in serum), vitamin D (25-(OH)- vitamin D3 parathyroid hormone in non-fasting venous blood samples), and bone stiffness (quantitative ultrasound). All outcomes were objectively measured.

1

RCTa

No risk of bias

No serious inconsistency

Very serious indirectnessb

No serious imprecision

None

422

The PA intervention (structured/organized PA) was not associated with improved bone mineral content [118].

LOWc

6

Cross-sectionald

Serious risk of biase

No serious inconsistency

No serious indirectness

No serious imprecision

Exposure/outcome gradientf

14,774

TPA was favourably associated with bone and skeletal health in 2 studies [119, 123] and not associated with bone and skeletal health in 1 study [124].

LPA was not associated with bone and skeletal health in 1 study [123].

MPA was favourably associated with bone and skeletal health in 1 study [123] and not associated with bone and skeletal health in 1 study [124].

MVPA was favourably associated with bone and skeletal health in 2 studies [122, 123] and not associated with bone and skeletal health in 1 study [124].

VPA was not associated with bone and skeletal health in 2 studies [123, 124].

Leisure time physical activity was favourably associated with bone and skeletal health in 1 study [123].

Outdoor activity was favourably associated with bone and skeletal health in 3 studies [119,120,121].

Weight-bearing activity was favourably associated with bone and skeletal health in 1 study [123].

VERY LOWg

  1. LPA: light-intensity physical activity; MPA: moderate-intensity physical activity; MVPA: moderate- to vigorous-intensity activity; PA: physical activity; RCT: randomized controlled trial; TPA: total physical activity; VPA: vigorous-intensity physical activity
  2. aIncludes 1 RCT [118]
  3. bThe intervention did not significantly change physical activity
  4. cQuality of evidence was downgraded from “high” to “low” because of very serious indirectness
  5. dIncludes 6 cross-sectional studies [119,120,121,122,123,124]
  6. ePotential confounders were not adjusted for in 2 studies [120, 121]. Potentially inappropriate statistical analysis: other movement behaviours were mutually adjusted for in the fully adjusted models in 1 study [123]. No psychometric properties were reported for the subjective physical activity measure in 4 studies [119,120,121, 123]. A convenience sample was used in 2 studies [120, 124]
  7. fA gradient for higher TPA, MPA, MVPA, leisure time physical activity, outdoor activity, and weight-bearing physical activity with better bone and skeletal health was observed in 2 studies [119, 123]
  8. gQuality of evidence was downgraded from “low” to “very low” because of serious risk of bias; because of this limitation, was not upgraded for an exposure/outcome gradient