Analyzes the influence of kinanthropometric and dynamometric variables on the Sit and Reach test in amateur athletes . We used twenty anthropometric variables, four dynamometry tests, the Sit and Reach test and the amount of physical activity practiced. Significant differences were found between men and women in terms of flexibility levels. The prediction equations were differed according to gender (30.6% men and 32.5% women), height being an influential factor in women. The general prediction equation calculated, the level is 39.1% (moderate). Men and women show significant differences in all anthropometric variables except subscapular and suprailiac skinfolds. What other factors influence the kind of results that can be expected? The results of the flexibility test are not influenced by the anthropometric and dynamometric variables, or by the type of physical activity performed. The strength index does not correlate with the Sit and Reach test value.