Physical Activity

Studies have found that undernourished children are less physically active than well-nourished children. Researchers investigated the effects of lipid-based nutrients supplements (LNS) on the physical activity levels of children born to Malawian mothers and found that LNS does not increase physical activity in Malawian toddlers.


Poor dietary intake and malnutrition are issues prevalent in developing nations; some of the greatest impacts are noted in the pediatric population. Previous studies have reported that small-quantities of lipid-based nutrient supplements (LNS) do not or only modestly promote growth in children living in developing nations. Physical activity in children is also influenced by their nutritional status. Studies have found that undernourished children engage in less physical activity than those who are well-nourished, yet, when their nutritional status improves, so do their activity levels. Reduced physical activity is a cause for concern as it may lead to poor child development.

The Supplementing Maternal and Infant Diet With High-energy, Micronutrient Fortified Lipid-based Nutrient Supplements (iLiNS-DYAD) was a randomized, controlled trial that aimed to assess the health impacts of providing small-quantity LNS to mothers during pregnancy and 6 months postpartum and, subsequently, to their infants from 6 to 18 months of age. Given that studies looking at the effects of nutrient supplementation on physical activity are rare, Pulakka and colleagues created a sub-study to the iLiNS-DYAD study being performed in Malawi; their hypothesis for this sub-study, published in the British Journal of Nutrition, was that children who received LNS supplementation would be more physically active at 18 months than children in the control group who did not receive LNS. The study was performed in a semi-urban and rural area of Mangochi District, an area in Southern Malawi that has a high prevalence of chronic infant undernutrition. Maternal enrollment for iLiNS-DYAD-Malawi had been performed through the antenatal clinics in Mangochi District Hospital, Malindi Hospital and Lungwena Health Centre. Researchers included mothers whose ultrasound confirmed a gestation period of 20 weeks or less. For the physical activity sub-study, Pulakka and colleagues recruited all participants who had attended the last clinic visit of the main trial at 18 months of age, when they were still receiving the intervention. Data collection occurred between January 2013 and March 2014. Of the 661 children who had activity measurements recorded at 18 months, enough data was collected to include 570 in the physical activity analysis.

Children in the intervention group were given 20 grams of small-quantity LNS daily from 6 to 18 months of age. Their mothers had received a daily dose of 20 grams of LNS during their pregnancy and for 6 months after delivery. The children in the control group did not receive any supplementation. Their mothers had received either (1) a daily capsule of iron-folic acid until delivery and one tablet of calcium (meant to function as placebo) from delivery to post-partum, or (2) one daily tablet of multiple micronutrients throughout the pregnancy and 6 months post-partum. The physical activity outcome was measured using an accelerometer which parents were instructed to secure to the child’s right hip, and was to be worn day and night, unless the child showed signs of discomfort. Ultimately, there was no significant difference in physical activity between the children who received LNS and those who did not, leading Pulakka and colleagues to conclude that LNS supplementation does not increase physical activity in this population of Malawian toddlers.

The study authors cite the following strengths of their study: it was randomized, thereby reducing the influence of extraneous factors on the outcomes, and reducing the likelihood of a selection bias; physical activity was measured using an objective tool to eliminate inaccuracies in parental reporting on physical activity levels; the requirements for inclusion in the study were very broad, making the results generalizable. One study weakness cited by the researchers was the fact that parents could not be blinded to the intervention their children were receiving, although this did not directly influence the physical activity measurements as they were recorded with accelerometers. The use of accelerometers was cited as a possible weakness, as the devices are not capable of providing information on activity type or context, or the causes of movement, which means the device would still capture movement while the child was being carried. However, most of the children were being carried one hour or less per day. The results reinforce the need for further investigation to identify interventions which could improve the general health and developmental outcomes of children living in areas where food security is an issue. The study authors also note that it would be beneficial to establish recommendations for children’s physical activity based on objective measures (such as those obtained with an accelerometer) rather than parental reporting.


Written By: Sara Alvarado BSc, MPH

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