Synopsis
The rear hand straight punch (also known as a cross punch) is arguably the most important technique utilised in combat sports. Therefore, in the current era where such a large emphasis is placed on maintaining an undefeated record, it is absolutely vital to fully optimise this technique. This article will explore the key kinematic and kinetic contributors of the rear hand straight punch, with the aim of providing coaches and athletes with the biomechanical understanding required to help develop peak punching performance.
Contents:
- Synopsis
- Introduction
- Kinematics and Kinetics of the Rear Hand Straight Punch
- Training recommendations
- Additional resources
- References
Introduction
The aim of many combat sports such as: Boxing, Kick Boxing, and Mixed Martial arts is to achieve victory by knocking out the opposing fighter. This is primarily achieved by utilising strikes to cause a rapid acceleration of the opponent’s head as this is the greatest predictor of causing a knockout, especially if the acceleration is in the axial plane (Fogarty et al., 2019). Consequentially, the RHSP (Rear Hand Straight Punch) has the potential to drastically change the results of a fight due to the large amount force produced by the punch as Force= Mass x Acceleration (Cheraghi et al., 2014; Smith et al., 2000). Additionally, elite boxers are observed to have significantly higher RHSP force than novice boxers ; and at an elite level, boxers that use straight punches more frequently are more likely to win the fight than boxers that don’t (Smith et al., 2000 Davis et al., 2015; Davis et al 2018). Thus, further demonstrating the importance of the RHSP technique regarding boxing performance and the outcome of a match. Therefore, it essential that both coaches and athletes in combat sports understand the biomechanical underpinnings of this technique and how to apply that knowledge to training.
Kinematics and Kinetics of the RHSP
Trunk rotation and rear leg extension are observed to be the greatest contributors to punch force in advanced boxers, at 37.42% and 38.46% respectively; whereas, arm extension only contributes 24.12% (Filimonov et al., 1985; Table 1). Additionally, well trained junior boxers are observed to make a greater contribution to punch force at the shoulder than in the trunk and legs than elite boxers (Dinu & Louis, 2020). Though, the same study did identify front foot GRF (ground reaction force) as a greater contributor to RHSP force than the rear leg (Dinu & Louis, 2020). Furthermore, when the trunk and lower body are fatigued, a significant decrease in punch force across all punch techniques has been observed (Dunn et al., 2021). Thus, corroborating the findings of Filimonov et al. (1985) and Dinu and Louis (2020) and demonstrating the importance of force development in the rear leg and trunk.
Table 1. Percentage force contribution (Filimonov et al., 1985)
The underpinning mechanisms explaining the contribution of trunk rotation and rear leg extension are prevalent in many striking and throwing events (Cabral et al., 2010). During the RHSP, the pelvis begins rotating towards the target whilst the trunk is still rotating away from the target (Cabral et al., 2010). This eccentric contraction of the agonists for the trunks forward rotation triggers the stretch-shortening cycle, as elastic potential energy and a stretch reflex are generated during the amortisation period of the trunk (Turner and Jeffreys, 2010). Consequentially, increasing the RHSP force as the additional force generated at the trunk is sequentially and accumulatively transferred to the punching hand (Bunn 1972). Though Cabral et als. (2010) study was limited to just one participant; the described mechanism is identical to the “X-factor” principle that is observed to increase peak clubhead and racket speed in Golf and Badminton respectively (Cheetham et al., 2001; Zhang et al., 2016). Thereby, corroborating the findings of Cabral et al. (2010).
The lower extremities are mainly considered to be the primary contributor RHSP force (Lenetsky
et al., 2013). There are three phases identified for the lower extremity chain, these are:
- Starting position
- Lead toe off
- Lead toe on
The last of these phases has been identified as the most important for force production (Tong-Iam et al., 2017). Moreover, a significant positive correlation is observed between peak lead leg GRF and peak hand velocity during the RHSP (Stanley et al., 2018); thus, supporting these claims. This is because after the rear leg extends (creating a propulsive force), the front leg then lands whilst rigid; resulting in a braking force which creates a horizontal torque on the pelvis and is then sequentially transferred through the body to the hand (Turner et al., 2011). This corroborates the findings of Dinu and Louis (2020). Additionally, the lower extremity chain described by Turner et al. (2011) has been identified in other sports such as fencing (Mulloy et al., 2018). Skilled fencers displayed significantly higher horizontal sword velocities and ankle extension velocities than novices, indicating a greater use of the lower extremity chain (Mulloy et al., 2018). Whilst there are fundamental differences between a RHSP and fencing lunge, Cheraghi et al. (2014) observed the same lower extremity chain in boxers; thus, suggesting the mechanism is utilised across the sports.
Figure 1. Motion capture of a RHSP.
Many of the mechanisms described can be observed when viewing the RHSP in slow motion (Figure 1), in this video it is clear that the rear leg extends first to provide the propulsive force, then the front leg lands creating a braking force that transfers a horizontal torque to the pelvis and trunk. The use of video analysis is an incredibly effective method of evaluating an athletes punch technique even in its most simple forms. Whilst the amortisation period between the pelvis and trunk is too fast to observe in the video, figure 2 shows that the pelvis does indeed begin to rotate towards the target before the trunk does.
Figure 2. Pelvis and trunk rotation of figure 1 punch from starting position to bag contact. Solid line: Trunk, Dotted line: Pelvis, LTO: Lead Toe On, BC: Bag Contact
Training recommendations
From the existing literature on the topic, it is evident that optimising the extension force of the rear leg, rotation force of the trunk/the trunks interaction with the pelvis, and ensuring that the front leg is rigid upon landing are essential for increasing the performance of the RHSP (Cabral et al., 2010; Dinu & Louis, 2020; Filimonov et al., 1985; Turner et al., 2011). This can be applied in practice.
Firstly, a strength, plyometric, and core training program can be utilised to develop muscular power, peak contraction force, and rate of force development in the trunk and rear leg muscles (Chelly et al., 2010; Suchomel et al., 2018). Strength training should be performed at 80-90% 1RM for 3-5 repetitions, and 4-8 sets (Baechle & Earle, 2008) and plyometric sessions should use 3-4 exercises for 2-4 sets of 6-15 repetitions (Bedoya et al., 2015). Additionally, jumping movements are observed to utilise the same lower extremity kinematic chain as observed in the RHSP (Bobbert, 2001); therefore, utilising plyometric movements in training would increase the efficiency of force transfer from the proximal to distal segments of the chain. Lastly, exercises such as a landmine twist should be performed under the strength training format to increase the rotational force of the trunk. For an example training programme, please download this worksheet.
Furthermore, sport specific drills can be used to emphasise landing with a rigid front leg and leading with the pelvis before rotating the trunk when performing the RHSP. This will allow a larger braking force to be generated and increase the stretch shortening effect between the pelvis and trunk, resulting in an increase in RHSP force (Cabral et al., 2010; Cheraghi et al., 2014).
Additional resources
References
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