3. At no point are body blocks, roll blocks, or shoulder blocks permissible (penalty is game disqualification and automatic suspension from league play). When blocking, offensive players may not keep their elbows out; they must be against the body. Defensive players can block with their arms down but it's not recommended.
4. Feet must be placed in line with the shoulders of the opponent to execute a legal block. Generally, feet should be positioned about hip-width apart. The goal is to drive through the blocker's legs and up into his torso.
5. Blockers are allowed only one block per play.
6. A player who engages in illegal blocking will be penalized by having any forward progress stopped along with any possible gains on the play. If a penalty results in first downs or touchdowns being awarded, the blockers will not receive credit for their efforts.
7. There is no such thing as an acceptable block. Any attempt to block below the waistline is illegal and should be avoided at all costs.
8. Only players involved in the play as designated runners or defenders are permitted to use hands to restrain opponents. For example, a linebacker may not use his hand to stop a runner from gaining additional yardage; instead, he should use his body to tackle the runner.
Blocking is mainly pushing with certain limitations; while blocking, one may not grip or drag another player, and hands may not reach beyond the line of each armpit; otherwise, a holding penalty will be imposed. A blocker can use his or her body to shield an opponent from making contact with another player.
There are three ways that players block: head-to-head, shoulder-shoulder, and arm-bar. When two players meet head-on, they go at it mano a mano—one on one. This is how most tackles are made in football. The player who makes the tackle gets credit for the stopgap but also takes risk of being injured by his or her opponent.
The next way players block is shoulder-to-shoulder. Here, one player tries to block another by throwing himself or herself in front of him or her. This is used primarily when there are more than two players involved in the play. For example, if a runner is trying to escape upfield and another defender catches him from behind, he would block him shoulder-to-shoulder.
Finally, players block by using their arms. An offensive lineman will try to prevent a defensive player from getting into the backfield by grabbing him or her around the waist with the arm pit.
In basketball, you can block a player as long as your feet remain immobile and your hands are kept to yourself. Any other type of blocking is regarded as a foul. Illegal guarding is the purposeful use of your body to delay or restrict the movement of an opponent player. This includes holding up arms, legs, and hips.
There are three types of illegal defenses: screening, hooking, and batting. In each case, the defender uses his or her body to impede an opponent's path to the basket.
Screens are used to open up driving lanes for teammates by removing defenders from the play. A screener cannot touch the ball until it has been passed to him or her by a teammate. Hooks are defensive maneuvers where the defender sticks his arm into the path of the on-ball player. This prevents the on-ball player from getting past him or her. Bats are used to defend against players who want to take themselves out of the game. If a player bats himself or herself out of contention, that player becomes ineligible to reenter the game.
A legal shot is one taken with proper form. An illegal shot is any shot not taken with proper form, including shots blocked with excessive force. Excessive force means using more than necessary force to block a shot. For example, if a defender uses only his or her forearm to block a shot, then it was not done with sufficient force.
Cut blocks are permissible until another offensive player engages a defensive player. Although some consider the approach unsportsmanlike because to the potential of significant harm, it is a tremendously successful tactic when taught and used appropriately. Blocking below the waist is prohibited.
Football blockers use various techniques to attempt to free their teammates from opposing players. In general, there are two types of blocks: open-field and downfield.
Open-field blocks are used to initiate contact with a defender and get him out of the way so a teammate can continue downfield. Open-field blocks can be either forward or backward. Forward blocks are used to attack defenders head-on; they're most effective if the blocker is able to engage more than one opponent at a time. Backward blocks target smaller areas on the body; they're useful for breaking up passes or stopping runners. Blocks should be delivered with enough force to make sure you disrupt your opponent's game plan but not so hard that you injure him.
Downfield blocks are used to break up passes or stop run plays by engaging and holding the defense back five or six yards while a teammate catches the ball. Downfield blocks can also be called "blitzes" because they bring pressure directly off the edge of the line.