Defining the Phases of Boxing Punches – A Mixed Methods Approach
Lenetsky, S; Brughelli, M;, Nates R.J; Neville, J.G; Cross, M.R; Lormier, A.V.
JOURNAL OF STRENGTH AND CONDITIONING RESEARCH: APRIL 2020 – VOLUME 34 – ISSUE 4
In many sports, common movements are separated into phases for the sake of optimising qualitative and quantitative analysis. These phases have traditionally been assigned following both kinetic (the forces or torques applied to the body) and kinematic (motion of the body) assessment (2,3)
Whilst multiple studies have examined the kinetics and kinematics involved with the biomechanics of boxing, no common consensus exists for terminology used to describe the phases of a punch. The aim of this study, therefore, was to use biomechanical analysis to propose a system of movement phase terminology for commonly used punches in boxing.
10 experienced boxers underwent examination of boxing technique during maximal force punches using a combination of force plate ground reaction force (the force exerted by the ground on the body) measurement, EMG measurement (measuring muscle contraction) and 2D video analysis. Assessments were performed for both front and rear hand straight and hook punches.
EMG measurement was taken for the following muscles:
Triceps Brachii (TB) Latissimus Dorsi (LD) Rectus Abdominis (RA) Rectus Femoris (RF)
Phases were defined following qualitative analysis of the 3 methods of data collection, and were broken down into 3 phases for the straight punches (initiation, execution, impact) and 4 phases for the hooks (wind up, initiation, execution, impact).
The description of the phases, along with the quantitative data, are summarised below:
|Left lead straight (jab)||Description||GRF||EMG|
|Initiation||Front foot steps or slides towards target, rear hand moves forwards, minimal torso rotation.||Initial loading of the rear leg vertically before propelling forwards towards the target. Peak vertical force at the end of the phase.||Increase in all muscles, peak in RRF.|
|Execution||Phase begins with the rear hand returning to guard position. Rotation of the torso begins, and as this rotation continues, the lead shoulder flexes and elbow extends towards the target||Continued forwards drive from the rear leg. Loading through the lead leg occurs just before impact.||RRA & LRA peak early. LRF rises in the middle of the phase, followed by peak of RLD. LLD and LTB peak just prior to impact.|
|Impact||Lead hand makes contact||Continued loading through the lead leg. Minimal loading through the rear leg.||All muscles decrease in activation.|
|Right rear straight (cross)||Description||GRF||EMG|
|Initiation||Counter rotation is combined with elbow flexion and shoulder extension of the attacking arm, with or without a movement forward of the lead hand||Initial push away from the target with the lead leg.||Peak in LRF early on, followed by LLD, then RRF, followed by RRA and LRA. Gradual rise in LTB throughout.|
|Execution||Either rear foot rotation or slight step forwards. Elbow extension and shoulder flexion occur towards the end of the phase.||Phase begins at peak force of the lead leg pushing away from the target, continuing as weight is transferred from the rear leg to the lead leg.||RRA, LRA, and RRF decrease. LTB peaks just prior to impact.|
|Impact||Rear hand makes contact||Force continues to drive forwards on the lead leg. Some force laterally away from the midline. Rear leg relatively unloaded.||RTB and RLB experience second peak at the end of impact|
|Left lead hook||Description||GRF||EMG|
|Wind up||Phase begins with flexion at the knees (particularly the lead leg). As this continues, rotation begins and the lead shoulder moves away from the target. Rotation combined with horizontal flexion, bringing the torso towards the front leg, as well as abduction of the shoulder.||Weight shift from rear leg to lead leg. Slight drive forwards and shift away from the midline.||Gradual increase in all muscles, double peak in LLD.|
|Initiation||Triple extension through ankle, knee and hip of lead leg. Torso counter rotates and laterally flexes back. Shoulder of the attacking arm continues to abduct.||Continued drive forwards with the lead leg.||Phase begins with peak in LLD & LTB, followed by RLD. RRF peaks at the end of the phase|
|Execution||Torso continues to rotate, Attacking arm remains flexed at the elbow and horizontally adducted. Foot rotation internally with the lead foot and externally with the rear foot act to move the lead shoulder closer to the target. Shoulder reaches peak abducted position just prior to impact.||Phase begins with peak propulsion in the opposite direction. As impact approaches, there is a drop in peak vertical loading.||LRA and RRA peak early in phase, followed by RTB. LRF peaks just before impact.|
|Impact||Lead hand makes contact||Forward drive off the rear leg||LLD, LTB reach a second peak at the end of impact.|
|Right rear hook||Description||GRF||EMG|
|Wind up||Rotation and horizontal flexion of the torso towards the rear leg combined with flexion at the knees.||Shift in load from lead leg to rear leg||RRF and RLD increase then decrease in activation. All muscles start to activate (in particular LLD)|
|Initiation||Reversal of the rotation and lateral flexion, with extension of the rear hip, knee and ankle. Rear arm pattern as per the left lead hook.||Transfer of load from rear leg to lead leg as rear leg drives forwards the target.||LLD and LRF peak early in phase|
|Execution||Rear root rotates internally, rear hand movements as per left hook||Lead leg approaches peak force directed away from the target. Increase in force applied away from the midline.||Phase begins with peak of RRA.|
|Impact||Rear hand makes contact||Rear leg drive into the target, continued force applied away from the midline.||LRA and LTB peak upon impact. RTB and RLD peak at the end of impact|
The methods applied to identification of phases were for the most part sound, and the resultant proposed phases provide a sensible framework for biomechanical analysis of punching techniques. The authors acknowledge the lack of a preparation or recovery phase in the proposed terminology, and argue the unpredictability of recovery from punching in actual boxing matches as a justification for its exclusion. I would argue, however, that whilst the later stages of recovery from throwing a punch may be unpredictable, the phase directly following impact (where in this study there were still peaks in certain muscles and significant changes in ground reaction force) should constitute an important element of boxing punch analysis.
Whilst the muscles analysed through EMG were sufficient to provide a quantitative picture of muscle firing patterns through different areas of the kinetic chain, it would have been interesting to see the activation of pectoralis major, lateral hip muscles, gluteus maximus and the internal and external obliques. Although not likely to influence the outcome of this study, such data may aid the sports scientist/strength and conditioning coach in addressing specific muscle deficits associated with performance in a certain phase.
Both GRF and EMG data of rectus femoris activation illustrated the pattern of transferring force from rear leg to front leg. Predictably, the ground reaction force (GRF) in the rear leg peaked just after initiation, while the GRF in the lead leg peaked just after impact. This “braking” effect of the front leg has been previously explored in boxing punches (4) and is thought to increase the rotational velocity through the hips and contribute to punching power. This reinforces the importance of developing quadriceps strength in the lead lead, and in particular eccentric loading capacity.
GRF data on the hook demonstrated a significant amount of lateral displacement, in combination with rotation. Traditional strength and conditioning programs focusing primarily on force production in the sagittal plane may be failing to optimise development of the necessary lateral hip muscle strength and power to maximise the power of the hook. Lower limb strength work should therefore incorporate some transverse and frontal plane exercises to address this.
In the introduction to the article, the authors made note of the double peak in muscular activation mechanism that has been proposed by McGill and colleagues to increase punching force (5). The EMG data from this study appears to corroborate these findings, showing a second muscular peak in the triceps brachii and latissimus dorsi upon impact. In addition, there appeared to be a triple peak present in the latissimus dorsi on the opposite side to the punching arm. The first peak occurred during the wind up as the body is rotated away from the opponent,
the second as the body rotates back towards the opponent, and the final peak upon impact. Traditional martial artists, particularly those from a karate background, will be familiar with the concept of the hikite, or retraction, whereby the opposite arm to the punching side is forcibly drawn back as the punch is simultaneously performed. Whilst there are combat applications to this retraction, biomechanically it is thought to improve speed and power in the punch through reciprocal muscle action. Although in boxing this exaggerated retraction is not performed, there is likely still some reciprocal action of the latissimus on the opposite side, and these findings may highlight the importance of developing this muscle.
Of final note was the decrease in activity of all muscles upon impact in the jab. For many athletes, the jab is utilised as more of a tactical tool to set up other punches to be delivered with greater force. It is possible that the more rapid relaxation of muscles upon impact is evidence of the lower levels of muscle contraction required.
Whilst this study lays promising groundwork in terms of proposing a system of terminology, the quantitative and qualitative analysis that follows will ultimately define the system’s utility both in research and in the field.
This study also only studied singular punches thrown in isolation. It would be interesting to see if these phases change with combinations.
The authors of this paper combined the expertise of both sports scientists and boxing experts, and applied a mixed methods, quantitative and qualitative approach to establishing phases of these 4 punches. Such studies performed as a collaboration are likely to facilitate improved communication between coaches and sports science practitioners, and increase the chances of this terminology translating into practice.