Table 3.

Performance of reach and grasp of IDA infants compared to non-anemic infants in light of normal development of reach and grasp around 9–10 months

Optotrak kinematic variable	IDA compared to IS	Normal developmental change around 9–10 mo
Peak aperture	No difference Huge effect size and a trend towards: ↑ IDA>IS	↓
Reach duration	No difference Very large effect size: ↓ IDA<IS	↑
Duration from peak aperture to first contact	No difference Very large effect size: ↓ IDA<IS	↑
Peak velocity	↑ IDA>IS	↓ (3); General developmental ↑ with possible ↓ specifically at 9 mo (2)
Number of MU	No difference Very large effect size: ↑ IDA>IS	↓ (3); no change (2)
Straightness ratio of hand trajectory	↑ IDA<IS	↓ (4); no change (1)
Path length	No difference Medium effect size: ↑ IDA>IS	No change
Duration from reach onset to peak velocity	No difference Very large effect size: ↓ IDA<IS	No change
Duration from reach onset to peak aperture	↓ IDA>IS	No normative data

Note. The direction of statistically significant differences is shown for each kinematic variable. Arrows show the direction of the difference to facilitate comparisons to expected changes during normal development. In the last column arrows show the direction of normal developmental changes expected around 9–10 months compared to earlier ages. When there is conflicting evidence in the normative longitudinal studies, the number of papers supporting each result is given in parenthesis.