A Growing Social Divide in Body Mass Index, Strength, and Fitness of Swedish Male Conscripts.

PURPOSE

The aim of the study was to monitor trends in socioeconomic inequalities in body mass index (BMI), cardiorespiratory fitness (CRF), and muscular strength over several decades in a population of Swedish males aged 18-19 years.

METHODS

The cohort consists of 1.5 million young men attending military conscript examinations from late 1968 to 2005. Parental education was used as a marker for socioeconomic conditions in the conscripts' families of origin. Changing gradient in BMI, CRF, and muscular strength in sons of parents with higher and lower educational attainment was evaluated during four periods covering 36 years.

RESULTS

Over the course of the obesity epidemic, BMI remained higher in conscripts with lesser (vs. higher) parental education. Moreover, the absolute difference in obesity prevalence between groups showed a continuous increase, from .6% to 3.9%, indicating growing inequalities. Regarding fitness, lower CRF was consistently associated with less parental education, but with no clear secular trend in the magnitude of the difference. Finally, social differences in muscular strength changed in direction, from lower strength among conscripts with higher parental education in the initial observation period to lower strength associated with lower parental education in the final decade studied.

CONCLUSIONS

Among Swedish conscripts entering adulthood, social gradients in BMI and obesity widened continuously between 1968 and 2005. An apparent reversal of the earlier gradient in muscular strength in young men may be related to societal trends in occupational and leisure-time physical activity over the observation period. This cohort is being continually monitored through national registries for obesity-related comorbidities in later life.