BOURBONNAIS, Ill. -- Offensive holding will be a significant point of emphasis for NFL officials this season, raising the possibility of a spike in penalties as players adjust to elevated rule enforcement.

According to guidance released over the weekend, existing rules on holding "will be more strictly enforced this season, particularly on the backside of the run play or line of scrimmage." Referee Adrian Hill, who visited the Chicago Bears training camp Monday, said the league is trying to eliminate a technique sometimes known as the "lobster block," where offensive linemen grab defenders around the torso or shoulders to prevent them from flowing to the play from the backside.

"Certain teams do it," Hill said, "and [the league] is trying to basically legislate it out of the game."

A video to be shown to every NFL player and coach offers three examples from recent history that would be penalized this season: blocks by the Los Angeles Rams' Andrew Whitworth, the Miami Dolphins' Laremy Tunsil and the Washington Redskins' Trent Williams.

In recent history, NFL points of emphasis have often produced an increase in flags during the preseason and early in the regular season. Last season, a one-week point of emphasis on offensive holding led to 94 such flags, 42% more than in any week since at least 2012.

The 2018 season also included a point of emphasis on roughing the passer, particularly instances where pass rushers fell on quarterbacks with all or most of their body weight. Officials threw 31 roughing flags in the first three weeks of the season before the competition committee issued a clarification. In total, there were a total of 119 roughing the passer calls for the season, 10 more than last season and 27 more than 2016.

In a less-noticed 2018 emphasis, officials called almost the same number of illegal contact penalties during the first five weeks of the season (31) as they did in the entire 2017 season. The season total of illegal contact calls nearly doubled from 2017, from 38 to 70.

For 2019, the NFL has issued a total of two points of emphasis: Offensive holding and a continued enforcement of the "helmet rule," which prohibits players from lowering their helmets to initiate contact with an opponent.