Spinal shrinkage as a measure of spinal loading in male Saudi university students and its relationship with body mass index

OBJECTIVE: To compare spinal shrinkage in obese and non-obese young male adults and to find any correlation between them.

METHODS: In 2006, 123 second-year male students studying in the Colleges of Medicine and Dentistry, King Faisal University, Dammam, Kingdom of Saudi Arabia, were examined for their weights, standing heights, and recumbent lengths. In this cross-sectional observational study, the students were grouped according to body mass index (BMI): normal range BMI <25; overweight BMI = 25-29.9; obese-BMI >30. Spinal shrinkage was calculated as the difference between standing height and the recumbent length of the subject. Influence of BMI on the magnitude of spinal shrinkage was compared by analysis of variance, and the relationship between spinal shrinkage and BMI was tested with Pearson's correlation test.

RESULTS: The obese group presented a significantly greater reduction in standing height (1.6% of recumbent length) compared to the normal group (1%) (p=0.019). Spinal shrinkage was found to be positively correlated with level of obesity (r=0.369).

CONCLUSION: Spinal shrinkage is positively correlated to BMI, which represents a persistent load on the spine in obese individuals. This conveniently demonstrable adverse effect of obesity might well be used as an instrument to inspire individuals to change their lifestyles.