In the intricate world of cricket, few topics generate as much technical debate as the laws surrounding bowling actions. The line between a legal delivery and an illegal "throw" is a fine one, governed by specific biomechanical principles. This glossary breaks down the key terms you need to understand this complex and often controversial aspect of the game, from the basic law to the technology used to police it.
Throw (Chucking)
A 'throw', or 'chucking', is an illegal bowling action where the bowler's arm is not straight at the point of delivery. According to Law 21.2, the bowler's arm must not extend (straighten) from the point of the arm reaching the horizontal until the ball is released. Any visible straightening or jerking of the elbow joint beyond a permitted tolerance level constitutes a throw, leading to the umpire calling a 'no ball'. This law exists to preserve the traditional skill of bowling and prevent bowlers from gaining an unfair advantage by "throwing" the ball at higher speeds or with exaggerated spin.Bowling Action
A bowling action is the complete sequence of movements a bowler uses to deliver the ball. It encompasses the run-up, the gather, the jump or bound, the delivery stride, the point of release, and the follow-through. The biomechanics of the action, particularly the angle and movement of the bowling arm at the shoulder and elbow, are scrutinised to ensure legality. A smooth, repeatable action is the hallmark of great bowlers like England seamer James Anderson.Elbow Extension
Elbow extension refers to the straightening of the bowler's elbow joint during the delivery swing. A certain degree of extension is natural and unavoidable due to human anatomy; the critical factor is how much. The International Cricket Council (ICC) permits a tolerance level of 15 degrees of elbow extension for most bowlers. Extension beyond this threshold is deemed illegal, as it transitions the action from a bowl to a throw.Straight Arm
The 'straight arm' requirement is the cornerstone of legal bowling. It doesn't mean the arm must be ramrod straight like a soldier's salute. Instead, it means the arm should not change its angle by straightening perceptibly during the delivery phase. The arm can be naturally slightly bent at the shoulder, but that flex should remain relatively constant from the moment the arm reaches horizontal until ball release.Umpire's Call
In the context of suspect actions, an umpire's call is the on-field official's decision to report a bowler for a potentially illegal bowling action. The umpire does not call 'no ball' for every suspected throw during a match—this would be overly disruptive. Instead, they make a report to the match referee after the game. The bowler is then required to undergo official testing at an ICC-accredited facility.Biomechanical Testing
Biomechanical testing is the scientific process used to analyse a bowler's action. The reported bowler is taken to a lab where high-speed cameras, sensors, and motion-capture technology measure the exact angles of their elbow and shoulder during delivery. This testing provides definitive data on the degree of elbow extension, determining whether the action is legal or exceeds the permitted tolerance levels.Tolerance Level (15-Degree Rule)
Introduced in 2005, the 15-degree tolerance level is the maximum amount of elbow extension permitted in a bowler's delivery. This rule acknowledged that almost all bowlers flex their arm to some extent. The 15-degree limit was established as the point where any further straightening becomes visible to the naked eye. This scientific basis helped move debates about throwing from subjective opinion to measurable fact.Jerking Action
A jerking action is a type of illegal delivery where the bowler visibly accelerates or 'jerks' their arm at the moment of release. This sudden, unnatural movement is often a clear indicator of throwing, as it typically involves rapid elbow extension. It differs from a smooth, rotational bowling action where the speed is generated through the shoulder and body momentum.Bent Arm
A bent arm in the delivery stride is not in itself illegal. Many world-class bowlers, especially spinners, have a naturally bent arm in their stock delivery. The illegality arises only if that bent arm straightens during the delivery phase. A bowler with a permanently bent arm that does not extend is bowling legally, albeit with an unusual action.Suspect Action
A suspect action is a bowling action that appears, to an umpire or match official, to violate the laws regarding throwing. When an action is deemed suspect, the bowler is officially reported. Being reported does not mean a bowler is guilty, but it mandates a review and possible biomechanical testing. Several international bowlers have had their actions questioned and subsequently remediated.Match Referee
The match referee is the senior official responsible for the overall conduct of the match. They receive reports from on-field umpires about suspect bowling actions. The referee then formally lays the charge and manages the process that follows, including notifying the player's board (like the England and Wales Cricket Board (ECB)) and the ICC.Remediation
Remediation is the process a bowler undergoes to correct an illegal action. Working with bowling coaches and biomechanists, the bowler attempts to modify their technique to reduce elbow extension to within legal limits. This can be a lengthy and challenging process, requiring changes to muscle memory. Success allows the bowler to be cleared and return to international cricket.Cleared Action
A cleared action is one that has been officially certified as legal following biomechanical testing. After a bowler is reported and undergoes remediation, they must return to an accredited lab and demonstrate that their elbow extension now falls within the 15-degree limit across all their deliveries. Once cleared, they are free to resume bowling at the highest level.Mankading
While not directly related to throwing, Mankading is another form of dismissal governed by the Laws of Cricket that often sparks debate. It is the run out of the non-striker by the bowler before delivery if the batter is out of their ground. It is a legal but controversial dismissal, famously executed by India's Ravichandran Ashwin and a topic of much discussion in the spirit of the game.No Ball
A 'no ball' is an illegal delivery. While it is called for various infringements (like overstepping the crease), a delivery deemed by the umpire to be a clear and obvious throw will also be called a no ball. The batting side is awarded one run, the delivery does not count in the over, and the batter cannot be dismissed off it (except via a run out, handling the ball, or obstructing the field).Delivery Stride
The delivery stride is the final stride a bowler takes before releasing the ball. It is a critical phase where the body braces to transfer energy from the run-up into the delivery. The positioning of the front foot and the alignment of the hips and shoulders during this stride can significantly influence the legality of the arm action that follows.Point of Release
The point of release is the exact moment the bowler lets go of the ball. The legality of the action is judged from when the bowling arm reaches the horizontal until this precise point. High-speed analysis focuses on this micro-second to measure the angle of the elbow and determine if any illegal straightening has occurred.Hyperextension
Hyperextension is a physiological condition where a bowler's elbow joint can extend beyond a straight line (beyond 180 degrees). This can make a legal action look like a throw to the naked eye, as the arm may appear to snap. Biomechanical testing is crucial here to distinguish between natural hyperextension and illegal elbow straightening.Drag
Drag is a term sometimes confused with throwing. It refers to the back foot of a bowler sliding along the ground in the delivery stride after the front foot has landed. While it can be a no ball if the back foot breaks the return crease, it is unrelated to the straightness of the arm and is a separate law entirely.Chucking Controversies
Throughout cricket history, several high-profile 'chucking controversies' have erupted, where the actions of famous bowlers have been widely questioned. These episodes often ignite fierce debate among fans, players, and pundits, highlighting the difficulty in consistently applying the law across different eras and bowling styles, from fast bowlers to mystery spinners.Law 21.2 (The Bowling Law)
Law 21.2 in the MCC Laws of Cricket is the specific regulation that defines a fair delivery with respect to the arm. It states: "The bowler's arm must not extend (i.e., straighten) from the point at which the arm reaches the level of the shoulder until the ball is released." This is the formal, written rule that all discussions on throwing ultimately reference.Bowling Review Group
The Bowling Review Group is an ICC panel of experts, including former players, umpires, and biomechanists. They review the reports and biomechanical data of bowlers with suspect actions. This group makes the final decision on whether a bowler's action is legal or illegal and oversees the clearance process after remediation.Pure Spin
Pure spin refers to the revolutions a bowler imparts on the ball using only the fingers and wrist, without any illegal arm action. The fear with throwing, particularly for spinners, is that a bent arm that straightens can generate extra pace and turn unfairly, compromising the skill of generating pure spin through wrist and finger technique alone.Fast Bowling
In fast bowling, the forces involved are immense, and the arm travels at great speed. This can sometimes make a legal, whippy action appear suspect. The 15-degree rule was particularly important for fast bowlers, as it recognised the natural flex caused by high-speed rotation and gravitational forces on the bowling arm.Doosra
The doosra is an off-spinner's delivery that turns away from the right-handed batter (like a leg break). Historically, bowling the doosra with a legal action has been biomechanically very challenging, leading several prominent bowlers to be reported for suspect actions when attempting it. It sits at the centre of many modern throwing debates in spin bowling.Understanding the rules around throwing is key to appreciating the skill and technique of bowlers at any level, from club cricket to the intense pressure of an Ashes series. While technology has brought clarity, the debate remains a fascinating part of cricket's fabric, ensuring the art of bowling continues to be a contest of skill within a fair framework.
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