Generally, the tackle bag is used to ‘train’ tackling. Arguably, more so at the junior and amateur levels. If we want to reduce the risk of injury, improve performance and correctly develop contact technique, I think the use of the cylindrical shaped foam filled bag needs to stop. Here’s why…
The origin and history of the tackle bag
Unfortunately, I was unable to track down the origin and history of the tackle bag. I do have a strong suspicion though that the punching bag used in boxing has something to do with it. Not knowing the history, I wonder where all the drills come from? Are coaches just perpetuating the blind use thereof? Why did the tackle bag receive so much popularity over the years? For the latter question, possible answers may be ease of use, storage, and the perceived low risk of injury to players during training (we’ll come back to this point later).
Mimicking the ball-carrier?
Just posing the question highlights all the limitations of the tackle bag. The main one of course being that the tackle bag does not move compared to the ball-carrier in a match. There are a number of others too, weight, distinction between body parts, counter-drive etc.
Tackling technique
The obvious, major contention with the tackle bag is the technique players are learning and executing while ‘tackling’ the cylindrical shaped foam filled bag. During training session using the tackle bag, players typically dive into contact. Add into the drill a conditioning component (a common practice), players tend to start falling into contact. Technically speaking, this goes against most (if not all) safe and effective techniques prescribed for executing a tackle. I will refrain from going into detail and compare specific techniques required for safe and effective tackling, and the techniques used when using the tackle bag – we try to keep these articles short.
Scientific Research?
Studies specifically comparing techniques executed when using different equipment compared to live tackle training and tackling during matches don’t exist (to my knowledge). With that said, the tackle bag is mentioned in some studies looking at the tackle event. For example, in a paper on attitude and behaviour of junior rugby union players towards tackling during training and match play, the tackle bag was ranked in the top five most frequently used methods for coaching the tackle. One of the lowest ranked methods was ‘‘live tackling in a 1 vs. 1 player grid’. These findings imply that coaches prefer using padded equipment such as the tackle bag or shield rather than live 1 vs. 1 tackling, perhaps in an attempt to safeguard the players from injury in training. While the use of the padded equipment may arguably lower the risk of injury in training compared to live tackling, tackle bags and shields do not mimic real match conditions, and therefore may increase the risk of injury in matches. Other studies used the tackle bag as part of their methods to investigate muscle activity around the shoulder when tackling, and the forces produced when tackling a stationary tackle bag.

Have I missed something? Thoughts?
Sharief Hendricks
References
Hendricks, S., Matthews, B., & Roode, B. (2014). Tackler characteristics associated with tackle performance in rugby union. European Journal of Sport Science. doi:10.1080/17461391.2014.905982
Usman, J., McIntosh, A. S., & Fréchède, B. (2011). An investigation of shoulder forces in active shoulder tackles in rugby union football. Journal of Science and Medicine in Sport, 1–6. doi:10.1016/j.jsams.2011.05.006
Horsley, I., & Herrington, L. (2006). Electromyographic analysis of the tackle within rugby football. Physical Therapy in Sport. doi:10.1186/1758-2555-1
Hendricks, S., Jordaan, E., & Lambert, M. (2012). Attitude and behaviour of junior rugby union players towards tackling during training and match play. Safety Science, 50(2), 266–284.