Objective: The aim of this study was to measure habitual physical activity in a group of Sereer adolescent females from Senegal. The hypothesis tested was that physical activity levels of adolescent Senegalese girls differ according to location and living conditions and may have a negative impact on growth and nutritional status.
Design: Studies of physical activity within the framework of a longitudinal study of growth during puberty.
Methods: All the adolescents were born and had been raised in the same rural communities, but some worked as maids in the cities during the dry season (migrants) while the others remained in the villages all year round in order to help their families in daily domestic and agricultural tasks (non-migrants). The study was undertaken in both rural and urban settings on a subsample of 40 migrant and 40 non-migrant girls aged 13.4-15.3, drawn from a cohort of 406 adolescents followed up since 1995. Nutritional status was estimated from anthropometric measurements; sexual maturation was based on stage of breast development and occurrence of menarche. Intensity and patterns of physical activity were derived from movement registration by accelerometry for a 3-day period. The nature and frequency of daily tasks were evaluated by questionnaires.
Results: As a whole, the adolescents studied here were smaller, thinner and less mature than girls of the same age from developed countries. Migrants weighed 3.5 kg more than nonmigrants and had more muscularity and a thicker fat subcutaneous layer. The day-to-day reliability of accelerometry counts was excellent (intraclass correlation coefficient: 0.90. 95% CI: 0.85-0.93). Mean daily (24 h) physical activity counts were higher for migrants than for non-migrants. Migrants spent more time engaged in moderate to heavy activity than did non-migrants (9.3 h/24 h versus 6.1 h/24 h). Non-migrants slept or were inactive for a longer period than migrants (7.6h/24h versus 6.3 h/24h). They also rested for a longer period of the day (2.1 h/24 h versus 0.8 h/24 h). When examining the influence of maturational status on physical activity, there was a clear difference between the two groups: the less mature migrants were more active, whereas the reverse was true in villages, where girls at the end of puberty reached higher intensity indices.
Conclusions and implications: In both situations, the activity level was high. The nutritional status of migrants was better despite a heavier work load. Differences could be explained by better living conditions and food intake in cities.