Which piece of equipment used in athletics was redesigned in 1986 because competitors were throwing it too far?

On 1 April 1986, the men's javelin (1.76 lb) was redesigned by the governing body (the IAAF Technical Committee). They decided to change the rules for javelin design because of the increasingly frequent flat landings and the resulting discussions and protests when these attempts were declared valid or invalid by competition judges. With throws exceeding 100 meters, it was becoming difficult to safely stage the competition within the confines of a stadium infield. The javelin was redesigned so that the centre of gravity was moved 4 cm (1.6 in) forward. In addition, the surface area in front of centre of gravity was reduced, while the surface area behind the centre of gravity was increased. This had the similar effect as feathers on an arrow. The javelin turns into the relative wind. As the javelin turns into the wind less lift is generated reducing the flight distance by around 10% but also causing the javelin to stick in the ground more consistently.