• helenbayne

The long (straight) arm of the (bowling) law

I’ve always thought this to be an unnecessarily emotive topic, although I do understand why. Primarily, I think, it’s because of the history of accusations towards bowlers as “chuckers”, implying intentional cheating on their part. My view, however, is that illegal actions are more often than not the result of poor technique that is unchecked. It is a major frustration of mine to see bowlers that have been reported by umpires for a suspected illegal bowling action needing to go through the unpleasant process of assessment, suspension and remediation, when this scenario is completely avoidable if coaches are able to identify flaws and rectify them before putting a player out onto the field. In this post, I will aim to give some guidelines on what to look for to identify suspect bowling actions and explain some of the common underlying technical faults.

First things first – what is an illegal bowling action? As explained in my previous post, the Laws of Cricket state that “A ball is fairly delivered in respect of the arm if, once the bowler’s arm has reached the level of the shoulder in the delivery swing, the elbow joint is not straightened partially or completely from that point until the ball has left the hand”. This rule differentiates bowling from throwing. Because almost no cricketers bowl with a completely locked elbow, the International Cricket Council (ICC) Regulations stipulate a maximum threshold of 15 degrees of elbow extension from the point at which the upper arm reaches horizontal until the ball is released.

The precise measurement of the elbow angle is extremely complex because it requires identification of the joint centres and rotation axes of the shoulder, elbow and wrist and the orientation of the upper arm and forearm. This can’t be done accurately and consistently using 2D video methods because of the 3D nature of the bowling action and joint motion – a camera would need to be aligned perpendicular to the plane of elbow flexion/extension for the entire period between upper arm horizontal and ball release, which is not feasible. However, with a trained eye, one can observe the pattern of elbow extension if it is present. The aim of this article is not to suggest how coaches or other observers can measure the elbow angle or decide whether an action is legal or illegal; it is to explain an approach to identify a pattern of elbow extension that one might suspect is illegal or could become illegal is left unchecked, as well as the underlying biomechanical causes that may be targeted through a coaching programme.


The phase of the bowling action that we’re interested in happens in one- to two-tenths of a second. So, high speed video is the coach’s friend! A camera that can capture >100 fps is ideal – there are a few consumer-grade cameras on the market that do a really good job. Failing that, many current smartphones have a high speed function that exceeds 100 fps. The drawback of smartphone cameras is that they use a digital zoom which decreases the image quality so it’s more difficult to position yourself in the ideal spot when filming the bowler. However, if this is all you have, it is a workable starting point.

You’ll want to record the bowler from a few different viewpoints and I’d recommend filming from in front, behind, directly side-on (on the side of the bowling arm), and at ~45 degrees in front. Play close attention to what you observe in real time as well. Studying technique in the field in combination with video review is a great way to train your eye.

The typical pattern of an illegal action is that the elbow is flexed at upper arm horizontal, maintains this angle or continues to flex to about half-way through the phase and then extends to the point of release. When reviewing the videos, start by looking at the arm when it reaches the horizontal and consider whether the elbow appears to be flexed, then play the video forward and see if it looks as though the flexion angle increases. When the upper arm passes ~45 degrees above horizontal, it is common to see the medial epicondyle (the inside of the elbow) leading when viewed from the front and the elbow extending thereafter, with the arm close to straight at ball release. If you identify this pattern, regardless of how big or small the range of elbow extension is, you should take steps to further analyse and improve the player’s technique.

There are a few confounding factors that can make it more difficult to clearly identify this pattern in certain individuals. Firstly, a bowler that is hypermobile may have increased abduction/adduction motion at the elbow joint (the forearm moving side-to-side relative to the upper arm) or hyperextension, both of which are not illegal but can be difficult to separate from true flexion/extension when watching a bowler. Secondly, structural anatomical variations – such as a large carrying angle, fixed elbow flexion, or unusual alignment of the wrist – can also give the impression of a suspect action when it is in fact legal.

Understand the why

Everything up to this point applies to both spin and fast bowlers. While there are similarities in some of the technical flaws underpinning an illegal action in both types of bowlers (such as being front-on with the upper body early in the delivery stride), there are some important details that are specific to each. So, from here onwards, I’ll focus only on the off-spin bowling technique.

A key factor in spin bowling performance is the ability to produce high revolutions on the ball. A biomechanical study by Spratford and colleagues showed that elite spin bowlers (playing at Test / international limited overs level) bowled with greater revolutions than ‘pathway’ bowlers (U19 national squads or list A cricket), who all had legal actions. They also found that pathway bowlers that used an illegal action outperformed the elite bowlers with legal actions, indicating that there is a potential performance advantage in the illegal technique. In the same study, illegal bowlers were more front-on with the pelvis and trunk at back foot contact, went through less pelvis rotation range from back foot contact to ball release, had slower rotation of the trunk, and finished with the trunk more front-on when the ball left the hand. Essentially, legal bowlers rely on the rotation of the body (pelvis and trunk) to generate spin, whereas illegal bowlers don’t use their body and have to rely on the arm to produce the same revolutions.

These research findings agree with what I’ve observed in practice. In addition, I’ve found the front-on alignment to be coupled with a flatter shoulder orientation as opposed to the “shoulder-over-shoulder” motion, which is a feature commonly recommended by coaches. The lower body also plays a vital role in setting up the action. Illegal bowlers tend to have a longer delivery stride and/or spend more time on the back foot with less aggressive back leg drive than legal bowlers. I talk this through in the following video:

Illegal bowling actions have historically been a source of scandal in international cricket and this has translated all the way down to junior school level. I hate to see the negative effect this has on young cricketers, at no fault of their own. Identifying and rectifying suspect actions is not straightforward but I’d really encourage coaches to take on the challenge, in the interest of the players.


Spratford, W., Elliott, B., Portus, M., Brown, N., Alderson, J. Illegal bowling actions contribute to performance in cricket finger-spin bowlers. Scand J Sci Med Sports. 2018; 28: 1691-1699. doi: 10.1111/sms.13070

Disclaimer: I am a member of the ICC Panel of Human Movement Specialists. No proprietary or confidential information is included in this article. All views are my own.


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