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The effect of core training on distal limb performance during ballistic strike manoeuvres

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Journal of Sports Sciences
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Abstract

Ballistic limb motion is enabled by proximal “core” stiffness. However, controversy exists regarding the best method of training this characteristic. This study sought to determine the most effective core training method to enhance distal limb athleticism. A total of 12 participants (24 ± 3 years, 1.8 ± 0.05 m, 76.8 ± 9.7 kg) consisting of Muay Thai athletes performed a core training protocol (Isometric vs. Dynamic, with Control) for 6 weeks, using a repeated measures design to assess performance (peak strike velocity, peak impact force, muscular activation) in various strikes. Isometric training increased impact force in Jab (554.4 ± 70.1 N), Cross (1895.2 ± 203.1 N), Combo (616.8 ± 54.9 N), and Knee (1240.0 ± 89.1 N) trials (P < 0.05). Dynamic training increased strike velocity in Jab (1.3 ± 0.2 m · s⁻¹), Cross (5.5 ± 0.9 m · s⁻¹), Combo (0.7 ± 0.1, 2.8 ± 0.3 m · s⁻¹), and Knee (3.2 ± 0.3 m · s⁻¹) trials (P < 0.05). Isometric training increased Combo impact force 935.1 ± 100.3 N greater than Dynamic and 931.6 ± 108.5 N more than Control (P < 0.05). Dynamic training increased Jab strike velocity 1.3 ± 0.1 m · s⁻¹ greater than Isometric and 0.8 ± 0.1 m · s⁻¹ more than Control (P < 0.05). It appears that both static and dynamic approaches to core training are needed to enhance both velocity and force in distal limbs.
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The effect of core training on distal limb
performance during ballistic strike manoeuvres
Benjamin Lee & Stuart McGill
To cite this article: Benjamin Lee & Stuart McGill (2016): The effect of core training on
distal limb performance during ballistic strike manoeuvres, Journal of Sports Sciences, DOI:
10.1080/02640414.2016.1236207
To link to this article: http://dx.doi.org/10.1080/02640414.2016.1236207
Published online: 03 Oct 2016.
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The effect of core training on distal limb performance during ballistic strike
manoeuvres
Benjamin Lee and Stuart McGill
Spine Biomechanics Laboratory, Department of Kinesiology, Faculty of Kinesiology, University of Waterloo, Waterloo, ON, Canada
ABSTRACT
Ballistic limb motion is enabled by proximal corestiffness. However, controversy exists regarding the
best method of training this characteristic. This study sought to determine the most effective core
training method to enhance distal limb athleticism. A total of 12 participants (24 ± 3 years, 1.8 ± 0.05 m,
76.8 ± 9.7 kg) consisting of Muay Thai athletes performed a core training protocol (Isometric vs.
Dynamic, with Control) for 6 weeks, using a repeated measures design to assess performance (peak
strike velocity, peak impact force, muscular activation) in various strikes. Isometric training increased
impact force in Jab (554.4 ± 70.1 N), Cross (1895.2 ± 203.1 N), Combo (616.8 ± 54.9 N), and Knee
(1240.0 ± 89.1 N) trials (P< 0.05). Dynamic training increased strike velocity in Jab (1.3 ± 0.2 m · s
1
),
Cross (5.5 ± 0.9 m · s
1
), Combo (0.7 ± 0.1, 2.8 ± 0.3 m · s
1
), and Knee (3.2 ± 0.3 m · s
1
) trials (P< 0.05).
Isometric training increased Combo impact force 935.1 ± 100.3 N greater than Dynamic and
931.6 ± 108.5 N more than Control (P< 0.05). Dynamic training increased Jab strike velocity
1.3 ± 0.1 m · s
1
greater than Isometric and 0.8 ± 0.1 m · s
1
more than Control (P< 0.05). It appears
that both static and dynamic approaches to core training are needed to enhance both velocity and
force in distal limbs.
ARTICLE HISTORY
Accepted 7 September 2016
KEYWORDS
Muay Thai; martial arts; per-
formance; core stability;
proximal stiffness; athleti-
cism; spine
Introduction
Striking martial arts such as Muay Thai involve ballistic limb
motion to deliver high impact force at maximal velocities to an
intended target. For centuries, these athletes have sought out
the most effective training methods to enhance their striking
speed, impact force, and other markers of performance. The
body is an articulated linkage where proximal stiffness and
stability is necessary to enable rapid movements of distal
segments (McGill, 2016). This mechanism requires the core
musculature (muscles proximal to the ball and socket joints
of the hips and shoulders) to prevent spine motion and but-
tress the torso, rather than generate movement akin to the
musculature of the distal limb segments. In this way, the core
muscles increased spinal stiffness and stability to prevent
unwanted torso motion when exerting against external loads
(Bergmark, 1987). Extending this concept to enhancement of
athletic performance, an athlete must generate sufficient stiff-
ness in the high mass torso for several reasons. First, proximal
stiffness in the torso reduces small eccentric movements,
representing a giving wayor energy loss, to enhance distal
limb motion velocity (McGill, 2014). Second, the spine is a
flexible column that must be stiffened to enable it to bear
more load without buckling (Bergmark, 1987). There is also
evidence of rapid muscle activation/relaxation sequencing in
high-performance athletes who seek more effective strikes
with higher limb speed and higher contact force at the term-
inal end of the linkage (hands or feet) (McGill, 2014; McGill,
Chaimberg, Frost, & Fenwick, 2010). When muscles contract,
they create both force and stiffness (Brown & McGill, 2009a).
Hence, the speed strength paradox is formed where muscle
force is needed in a pulse-like fashion to initiate limb speed
followed with relaxation to decrease stiffness to enhance clos-
ing velocity between the hand and the target. Thus, it appears
that an interplay between activation and relaxation, working
to create both an inertial high mass torso with rapidly moving
limb segments is a necessary condition of proficient striking
performance. There has been little formal investigation into
enhancement of these mechanisms. This study sought to
determine the most effective core training method (between
Isometric or Dynamic approaches) to enhance distal limb
athletic performance (impact force and strike velocity).
Numerous investigations into the relationship between
core stiffness/stability, training, and athletic performance
have yielded varied results. Nesser, Huxel, Tincher, and
Okada (2008) found weak correlations between Isometric
core stability and strength, speed, and power in football
players, and concluded that implementing core training pro-
tocols would not substantially enhance athletic performance.
However, this investigation only correlated performance and
endurance measures without examining if training core endur-
ance affected performance. Taanila et al. (2009) showed
improvements in military testing parameters, including sit-up
endurance tests, after training with Isometric core exercises.
Both Willardson (2007) and McGill (2014) have discussed the
CONTACT Stuart McGill mcgill@uwaterloo.ca Spine Biomechanics Laboratory, Department of Kinesiology, Faculty of Kinesiology, University of Waterloo,
200 University Ave. W., Waterloo, ON N2L 3G1, Canada
JOURNAL OF SPORTS SCIENCES, 2016
http://dx.doi.org/10.1080/02640414.2016.1236207
© 2016 Informa UK Limited, trading as Taylor & Francis Group
use of core stability exercise to enhance sport performance by
buttressing the torso to facilitate distal limb motion. McGill
et al. (2010) commented on the speed/strength and force/
stiffness paradox after observing activation patterns termed
as the double peakin elite mixed martial arts (MMA) athletes
when striking. Muscles when activated create both, force and
stiffness. But stiffness slows rapid motion so that pulse pat-
terns of activation are needed to create high limb velocity.
Specifically, a muscular pulse in the torso and limbs initiate
limb movement. This is followed by a relaxation phase as the
closing velocity of the hand/foot to the target increases. Elite
athletes then produce a second impulse at impact to create a
stiffened resulting in a larger effective massand a higher
strike force. Coaches refer to this as getting the body behind
the forceor turning the body to stone, so there is minimal
energy loss. McGill (2014) reported a similar pulsing phenom-
enon in sprinters and golfers at impact. The idea of enhancing
effective mass to heighten impact force was hypothesised by
Blum (1977), Neto, Magini, and Saba (2007), and Pain and
Challis (2002). Within the world of martial arts, research dating
back to 1985 addressed performance differences between
novice and elite boxers (Filimonov, Koptsev, Husyanov, &
Nazarov, 1985). We were generally interested in training tech-
niques to enhance elite strike performance. While there has
been some work examining the role of strength and condi-
tioning training to improve martial arts performance (Turner,
2009), we could not find data that assessed torso stiffness,
limb speed, or strike effectiveness. Anecdotally, methods of
training muscular relaxation have been used by martial artists
(Little, 2001; Tsatsouline, 2006). However, the lack of investiga-
tion into which training exercises enhance strategic muscle
pulses and core stiffness, and whether they actually enhance
performance motivated this research. We chose a population
of Muay Thai trained athletes given their athletic objectives of
limb speed and strike force enhancement.
Isometric core exercises have been demonstrated to suffi-
ciently create activation of the core musculature (Axler &
McGill, 1997; Callaghan Gunning, & McGill, 1998; Kavcic,
Grenier, & McGill, 2004; McGill & Karpowicz, 2009), while spar-
ing the spine from excessive loads and injurious movement
patterns. Dynamic core exerciseshave similarly been
assessed for muscle activation patterns and in some cases
joint loading (McGill, Cannon, & Anderson, 2014, McGill,
Karpowicz, & Fenwick, 2009; McGill, Karpowicz, Fenwick, &
Brown, 2009, McGill, Marshall, & Andersen, 2013; McGill,
McDermott, & Fenwick, 2009). However, their ability to influ-
ence speed/force strikingperformance has not been
assessed. Collectively, this large body of evidence suggests
that core exercises influence stiffness and corresponding
joint loading but the influence on speed/strength perfor-
mance remains unknown. This study tested an approach that
has been proven to enhance short-term stiffness in the torso
(Lee & McGill, 2015) which to the authorsknowledge, but the
effect on athleticism remains unknown. The specific question
was: What core training style is best suited to enhance strike
force and speed of Muay Thai striking an Isometric or
Dynamic training approach? It was hypothesised that
Dynamic core training would better improve strike speed
than an Isometric approach or no (Control) training, while
Isometric core training would enhance strike impact force
better than a Dynamic approach or no (Control) training
given existing evidence for enhancing effective mass.
Methods
Experimental approach to the problem
A repeated measures test/retest protocol was used to examine
changes in biomechanical performance measures (impact force,
strike velocity, and core and hip electromyography signals) after
a 6-week core training protocol consisting of Isometric bracing or
Dynamic movement exercises in 12 male Muay Thai athletes. All
participants were recruited and trained between March 2013 and
June 2013 during daytime hours. As physiological markers of
health and performance were not within the scope of the study
controls for nutrition and hydration were not used. Participants
Muay Thai strike performance was measured before and after a
6-week training period (or waiting period for the Control group).
After the initial data collection, participants were divided into an
Isometric training group, Dynamic training group, or Control
group. Isometric and Dynamic training groups performed a train-
ing programme progressing in intensity-based on static-bracing
exercises and movement/speed-based exercises, respectively.
Participants
A total of 12 young healthy (24.2 ± 2.9 years, 1.8 ± 0.05 m,
76.8 ± 9.7 kg) were selected from a population of club Muay
Thai fighters; a martial art native to Thailand involving stand-
ing striking with the fists, elbows, knees, and shins. Exclusion
criteria consisted of any individuals who have experienced low
back pain or injury currently or within the past year.
Participants were trained in Muay Thai boxing for at least
1 year (range: 1.56 years of consistent training) with the
majority (10) having competitive amateur records and 2 parti-
cipants being provincial and international amateur champions
in their respective weight classes.
All participant recruitment and data collection procedures
were performed in accordance with University Office of
Research Ethics guidelines. The participants were informed of
the purpose and method of the study to ensure that they
understood completely, and each provided written informed
consent to participate. Participants were also informed that at
any time during the data collection or training protocol they
were free to withdraw from the study. Written informed con-
sent was gained in agreement with University guidelines.
Procedures
Muay Thai strike performance was assessed using strike
impact force strike velocity and electromyography signals. All
3 were measured during 4 trials of Muay Thai strikes,
described below, before, and after a 6-week intervention of
core training or rest. The training intervention consisted of 3
groups, each with 4 participants; 1 group performed Isometric
core exercises, 1 group performed Dynamic core exercises and
the Control group performed no special exercises during this
period.
2B. LEE AND S. MCGILL
Strike trials
The martial art of Muay Thai involves 2 competitors striking at
each other while standing using points of their fists, elbows,
knees, and shins. To gather information regarding the efficacy
of these strikes, 4 trials were selected typical to strikes used in
Muay Thai training and competition. All strikes were per-
formed from the participants dominant stance in which a
right-handed participant would stand with their left leg and
arm in front and right leg behind them, in a shoulder width
stance; and vice versa for a left-handed participant. The 4 trials
used were a Jab (lead hand strike with the fist), Cross (rear
hand strike with the fist), Knee (rear leg strike impacting with
the tip of the knee), and JabCross combination (aka Combo,
a Jab followed in succession by a Cross), as illustrated in
Figure 1. Three repetitions of each trial were performed in a
randomised order as to eliminate any bias or learning effect,
with 12 min of rest between each trial to reduce peripheral
fatigue between trials. Researchers also confirmed before each
trial that the participant was adequately rested and ready to
perform.
Instrumentation
Electromyography (EMG) signals, whole body kinematics, and
strike force were collected during strike trials. Data sources
were connected to Vicon MX Ultranet hardware (Vicon MX,
Vicon Motion Systems, Oxford, UK) and synchronised during
data collection using Vicon Nexus 1.8 software (Vicon MX,
Vicon Motion Systems, Oxford, UK). All signals were collected
at various frequencies and down-sampled to 60 Hz during
post-processing.
Figure 1. Examples of each of the strikes tested pre/post-core training. (a) Jab, (b) Cross, (c) JabCross Combination (Combo), (d) Knee.
JOURNAL OF SPORTS SCIENCES 3
Electromyography
EMG signals were collected on bilateral core and hip muscu-
lature using pre-gelled, disposable, monopolar AgCl disc-
shaped surface electrodes (30 mm diameter, Medi-traceTM
100 Series Foam Electrodes, Covidien, MA, USA) placed on
the skin over each muscle of interest (rectus abdominis [RA],
external oblique [EO], internal oblique [IO], latissimus dorsi
[LD], upper erector spinae [UES], lower erector spinae [LES],
gluteus maximum [GMax], gluteus medius [GMed]). Briefly,
normalised signals were obtained as follows. Signals were
amplified (±2.5 V; AMT-8, Bortec, Calgary, Canada; bandwidth
101000 Hz, common mode rejection ratio (CMRR) = 115 db at
60 Hz, input impedance = 10 GX) and sampled at 2048 Hz,
low-pass filtered with a 500 Hz, rectified and low-pass filtered
at 2.5 Hz (single pass second order) to mimic the frequency
response of torso muscle after Brereton and McGill (1998) and
normalised to the maximum voltage produced during max-
imum voluntary contraction (MVC) trials to produce a linear
envelope mimicking the muscle force output; a technique
used many times before [5]. Maximum effort to elicit max-
imum neural drive was the goal of the MVC trials. MVCs were
obtained using 4 postures: (1) a modified sit-up position in
which participants isometrically attempted to produce trunk
flexion, side bend, and twist motions against resistance, (2)
Isometric trunk extension while cantilevered in a prone posi-
tion over the edge of a table (Biering-Sorensen position)
against external resistance, (3) Isometric wide grip pull-up
posture in which the participant attempted to isometrically
pull against a horizontal bar while being resisted with instruc-
tions of maintaining a maximally tight grip and attempting to
bend the barwhile pulling vertically, and (4) side lying
abduction position where participants lay on 1 side and
attempted to produce hip abduction against resistance. All
EMG signals were normalised to a per cent MVC which
allowed day-to-day comparisons of muscle activation ampli-
tude with maximal values of the enveloped signal reported.
Limb kinematics
Three-dimensional (3D) whole body kinematics were recorded
using an infrared motion analysis system (Vicon MX, Vicon
Motion Systems, Oxford, UK) using an 8 camera set-up
sampled at 60 Hz. Rigid clusters were attached on the thorax,
pelvis, upper arms, forearms, hands, thighs, shanks, and feet;
each cluster with 4 reflective markers except the thighs, con-
taining 5 markers. Jab, Cross, and JabCross limb velocities
were measured from the displacement of the striking hands
cluster. The location of the hand cluster was calculated by
taking the average of the 3D location coordinates 4 markers.
Velocity was then calculated using a numerical differentiation
of each coordinate, as per the following equations:
Vx¼X2X1
t2t1
(1)
Vy¼Y2Y1
t2t1
(2)
Vz¼Z2Z1
t2t1
:(3)
Velocities about each axis were then normalised to a scalar
magnitude using the equation:
Vlimb ¼ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
V2
xþV2
yþV2
z
q:(4)
Strike force
A portable pancakeforce transducer designed for impact use
(AMTI, Massachusetts, USA) was mounted to a fixed surface to
record strike force. A steel cylinder was mounted to the trans-
ducer with a padded body protector, typically worn to protect
boxing trainers from strikes to the body, wrapped around the
circumference to act as a target. As all strikes across all parti-
cipants were measured in this manner, the damping effect of
the body protector was not accounted for in impact force
measurements. Impact data were sampled at 2160 Hz and
filtered with a second-order dual pass Butterworth filter with
cut-off frequency of 100 Hz. Cut-off frequency was determined
using a fast Fourier transformation; filtering, processing, and
analysis were performed via MATLAB software (Version r2012a;
The MathWorks Inc., Natick, Massachusetts, USA).
Core training protocols
Participants trained for 6 weeks using either Isometric or
Dynamic core exercises (the Control group did not train). All
participants were asked to refrain from performing any core
exercises outside of those assigned by researchers during the
study. The Isometric training group performed static exercises
designed to challenge the core musculature via bracing cues.
The Dynamic training group performed exercises based on
torso movement. Both training programmes were matched
for volume and intensity and periodised to increase challenge
every 2 weeks, dividing each programme into 3 phases (Tables
1and 2for a description of the progressive programmes).
Statistical analyses
Statistical tests were performed using IBM® SPSS® Statistical
software (Version 19, IBM Corporation, Somers, New York,
USA). 3 × 2 repeated measures analysis of variance (ANOVA)
(3 groups, before and after training) was conducted for com-
paring peak impact force peak EMG amplitudes, and peak
strike velocity; within and between training groups. Where
applicable, post hoc analyses were performed using the
Tukey honest significant difference (HSD) test when a signifi-
cant effect was detected with statistical significance set at
P0.05.
Results
Impact force, strike velocity, and torso and gluteal EMG were
measured before and after a 6-week bout in the 3 groups:
Isometric, Dynamic, or no core training (Control group).
4B. LEE AND S. MCGILL
Table 1. Isometric training protocol.
Exercise Sets ×Reps Freq Sets ×Reps Freq Comments
Week 1 Week 2
Plank 5,4,3,2,1 × 10 s 4× per week 5,4,3,2,1 × 10 s 7× per week Focus on quality of core contraction and
postural cues. Descending pyramid
sets (Start at 5 reps at 10 s each, next
set decrease 1 rep, continue to
decease 1 rep per set)
Bird dog 5,4,3,2,110 s 4× per week 5,4,3,2,1 × 10 s per side 7× per week
Side bridge 5,4,3,2,1 × 10 s 4× per week 5,4,3,2,1 × 10 s per side 7× per week
Torsional buttress 5,4,3,2,1 × 10 s per side 7× per week Focus on quality of core contraction and
postural cues. Use a hold time before
shaking begins, maximum 10 s
Week 3 Week 4
Anterior pallof press 5,4,3,2,1 × 10 s 4× per week Same volume, increase load 4× per week Focus on quality of core contraction and
postural cues
Posterior pallof press 5,4,3,2,1 × 10 s 4× per week Same volume, increase load 4× per week
Suitcase hold 5,4,3,2,1 × 10 s per side 4× per week Same volume, increase load 4× per week
Anti-rotation pallof press 5,4,3,2,1 × 10 s per side 4× per week Same volume, increase load 4× per week
Week 5 Week 6
Stir the pot 5×10 s per direction 4× per week 5×10 s per direction 4× per week Begin on knees, progress to toes. If 10 s
are not feasible, train below and
progress through the phase
Inverted row Up to 5×10 4× per week 5×10 4× per week If 10 reps are not feasible, perform as
many reps as possible and maintain
static posture. Focus on keeping torso
straight (avoid hip hiking/sagging)
Kettlebell unilateral rack walk 3×30 m walk per side 4× per week Same volume, increase load 4× per week Focus on core contraction and upright
posture (avoid lateral lean)
Half kneeling woodchop Up to 5×10 per side 4× per week 5×10 per side 4× per week If 10 reps are not possible, perform as
many reps as possible and progress
through the phase.
JOURNAL OF SPORTS SCIENCES 5
Table 2. Dynamic training protocol.
Exercise Sets ×Reps Freq Sets ×Reps Freq Comments
Week 1 Week 2
Curl up Up to 5×10 4× per week Up to 5×10 7× per week Focus on quality of muscular contraction;
visualise muscular activation throughout
motion. A total of 10 repetitions per set
with sets performed until marked
muscular fatigue sets in (up to 5 sets)
Superman Up to 5×10 4× per week Up to 5×10 7× per week
Side curl up Up to 5×10 per side 4× per week Up to 5×10 per side 7× per week
Twisting curl up Up to 5×10 per side 4× per week Up to 5×10 per side 7× per week
Week 3 Week 4
Advanced curl up (limbs extended) Up to 5×510 4× per week Up to 5×510 4× per week Begin with 5 × 5 and progress repetitions to
10. If 10 reps per side are too easy add/
increase weight
Back extension Up to 5×510 4× per week Up to 5×510 4× per week
Russian barbell twist Up to 5×510 per side 4× per week Up to 5×510 per side 4× per week
Week 5 Week 6
Curl up twitch Up to 5×510 4× per week Up to 5×5-10 per week Begin unweighted and focus on twitch
speed and rate of activation/relaxation.
Begin with 5×5 and progress repetitions
to 10. If 10 reps per side are too easy,
add/increase weight
Superman twitch Up to 5×510 4× per week Up to 5×510 4× per week
Lateral medball throw Up to 5×5-10 per side 4× per week Up to 5×5-10 per side 4× per week Ball velocity comes from torso movement,
not arms. Begin with 5×5 and progress
repetitions to 10. If 10 reps per side are
too easy, add/increase weight
Rotational medball throw Up to 5×5-10 per side 4× per week Up to 5×5-10 per side 4× per week Ball velocity comes from torso movement,
not arms. Begin with 5×5 and progress
repetitions to 10. If 10 reps per side are
too easy, add/increase weight
6B. LEE AND S. MCGILL
Impact force
Isometric and Dynamic trainings increased impact force in
almost all strike trials. Jab impact force increased by 17.9%
after Isometric training (2539.3 ± 89.13093.7 ± 69.4 N)
(F(1,3) = 70.8, P<0.001,β= 1.0), and by 18.3% after Dynamic
training (2614.7 ± 493.13199.6 ± 437.9 N) (F(1,3) = 34.1,
P=0.01,β= 0.9). Knee impact force increased by 13.1% after
Isometric training (8242 ± 132.39482 ± 152.8 N) (F(1,3) = 16.2,
P=0.03,β= 0.8), compared with a 7.1% increase after Dynamic
training (F(1,3) = 10.3, P=0.05,β= 0.7). Cross impact force
increased by 27% after Isometric training (5008.6 ± 76.3
5008.6 ± 76.3 N) (F(1,3) = 73.4, P<0.001,β=1.0)but
Dynamic training did not elicit any significant increases or
decreases. The Control group did not experience any significant
changes in impact force.
Comparing between training groups, Isometric training
increased impact force more than Dynamic training for Cross,
Combo, and Knee trials, and was superior to the Control group
for all strike trials. Dynamic training yielded greater effects in
increasing impact force than the Control group for Jab and
Knee trials, but was not more effective than the Isometric
group for any trials. The Control group did not show any effects
in increasing impact force more than Isometric or Dynamic
training. Isometric training increased Cross impact force by
1895.2 ± 155.2 N, compared with a 232.2 ± 30.9 N decrease
after Dynamic training (F(1,6) = 36.5, P<0.001,β=0.8)and
229.5 ± 40.1 N decrease after Control (F(1,6) = 40.1, P<0.001,
β= 0.8). Similarly, Isometric training increased Knee impact
force by 1240.0 ± 143.2 N, while after Dynamic training Knee
impact force decreased by 660.3 ± 101.8 N (F(1,6) = 6.9,
P=0.04,β= 0.7) and 299.7 ± 41.5 N decrease after Control (F
(1,6) = 44.5, P<0.001,β=1.0).
These results are summarised in Tables 3 and 4, and
Figure 2.
Strike velocity
Isometric and Dynamic trainings both increased peak limb
velocity for almost all strike trials. Peak strike velocity
increased within the Isometric training group during Cross
trials by 23.9% (6.7 ± 0.78.8 ± 0.9 m · s
1
) (F(1,3) = 34.3,
P= 0.01, β= 0.8) and the second strike of Combo trials by
5.2% (7.1 ± 0.59.0 ± 1.0 m · s
1
) (F(1,3) = 16.5, P= 0.03,
β= 0.7). Dynamic training increased peak strike velocity for
Jab trials by 22.4% (4.5 ± .45.8 ± .6 m · s
1
) (F(1,3) = 103.2,
P= 0.006, β= 0.9), Cross trials by 45.5% (6.6 ± 0.9
12.1 ± 1.3 m · s
1
) (F(1,3) = 140.9, P< 0.001, β= 1.0), Combo
trials by 13.2% (7.6 ± 0.810.4 ± 1.0 m · s
1
) (F(1,3) = 34.7,
P= 0.01, β= 0.8), and Knee trials by 29.1% (7.8 ± 0.6
11.0 ± 1.0 m · s
1
) (F(1,3) = 12.6, P= 0.04, β= 0.7). No changes
were measured within the Control group.
Comparing between training groups, Isometric training had
a greater effect on increasing strike velocity than Control for
Cross, Combo, and Knee trials (P< 0.05 for al trials), but did
not increase strike velocity more than Dynamic training during
any trials. Isometric training increased strike velocity during
Cross trials by 2.1 ± 0.3 m · s
1
compared with a
0.3 ± 0.1 m · s
1
increase after Control (F(1,6) = 13.9,
P= 0.01, β= 0.8), and increased the first and second strikes
of the Combo trials by 0.3 ± 0.04 and 1.9 ± 0.1 m · s
1
increase,
respectively, compared with a 0.6 ± 0.1 and 0.5 ± 0.05 m · s
1
decrease after Control (F(1,6) = 9.0, P= 0.03, β= 0.8; F
(1,6) = 8.5, P= 0.03, β= 0.7). Isometric training also increased
Knee strike velocity by 1.2 ± 0.1 m · s
1
compared with a
0.4 ± 0.05 m · s
1
increase after Control (F(1,6) = 9.8,
P= 0.02, β= 0.8). Dynamic training had a greater effect on
increasing strike velocity compared with Isometric training
and Control for all trials. Jab velocity increased by
1.3 ± 0.1 m · s
1
after Dynamic training, compared with a
0.0 ± 0.04 m · s
1
change after Isometric training
Table 3. Detailed statistics for impact force within each training group.
Trial
Stats (F-value, P-value, power)
Isometric Dynamic Control
Jab Pre F(1,3) = 70.8, P< 0.001,
power = 1.0
F(1,3) = 34.1, P= 0.01,
power = 0.9
F(1,3) = 5.1, P> 0.05,
power = 0.2Post
Cross Pre F(1,3) = 73.4, P< 0.001,
power = 1.0
F(1,3) = 2.6 , P> 0.05,
power = 0.1
F(1,3) = 4.9, P> 0.05,
power = 0.2Post
Combo Pre F(1,3) = 8.04,
P> 0.05,
power = 0.4
F(1,3) = 10.2,
P= 0.05,
power = 0.7
F(1,3) = 2.0,
P> 0.05,
power = 0.1
F(1,3) = 2.3,
P> 0.05,
power = 0.1
F(1,3) = 5.2,
P> 0.05,
power = 0.2
F(1,3) = 2.5,
P> 0.05,
power = 0.1
Post
Knee Pre F(1,3) = 16.2, P= 0.03,
power = 0.8
F(1,3) = 10.3, P= 0.05,
power = 0.7
F(1,3) = 2.4, P> 0.05,
power = 0.1Post
Table 4. Detailed statistics for impact force between each training group.
Trial
Stats (F-value, P-value, power)
Iso/Dyn Dyn/Con Iso/Con
Jab Pre F(1,6) = 8.2, P= 0.03,
power = 0.7
F(1,6) = 6.1, P= 0.05,
power = 0.7
F(1,6) = 0.3, P> 0.05,
power = 0.07Post
Cross Pre F(1,6) = 36.5, P< 0.001,
power = 0.8
F(1,6) = 0.3, P> 0.05,
power = 0.07
F(1,6) = 40.1, P< 0.001,
power = 0.8Post
Combo Pre F(1,6) = 3.8,
P> 0.05,
power = 0.2
F(1,6) = 44.4,
P< 0.001,
power = 0.8
F(1,6) = 2.4,
P> 0.05,
power = 0.3
F(1,6) = 0.4,
P> 0.05,
power = 0.1
F(1,6) = 1.9,
P< 0.05
power = 0.2
F(1,6) = 41.2,
P< 0.001,
power = 0.9
Post
Knee Pre F(1,6) = 6.9, P= 0.04,
power = 0.7
F(1,6) = 6.0, P= 0.05,
power = 0.7
F(1,6) = 44.5, P< 0.001,
power = 1.0Post
JOURNAL OF SPORTS SCIENCES 7
(F(1,6) = 34.2, P< 0.001, β= 1.0) and 0.5 ± 0.05 m · s
1
increase
after Control (F(1,6) = 8.7, P= 0.03, β= 0.7). During Cross trials,
Dynamic training increased strike velocity more than Isometric
training (5.5 ± 0.6 m · s
1
increase compared with a
2.1 ± 0.3 m · s
1
increase, respectively) (F(1,6) = 6.0, P= 0.05,
β= 0.7), and Control (0.3 ± 0.05 m · s
1
increase after Control)
(F(1,6) = 18.3, P= 0.008, β= 0.9). Dynamic training increased
Combo velocity by 0.7 ± 0.08 and 2.8 ± 0.2 m · s
1
for the first
and second strikes, respectively, compared with Isometric
training which increased velocity by 0.3 ± 0.05 and
1.9 ± 0.2 m · s
1
, respectively (F(1,6) = 6.1, P= 0.05, β= 0.7;
F(1,6) = 6.3, P= 0.05, β= 0.7), and Control where strike velocity
decreased by 0.6 ± 0.1 and 0.5 ± 0.05 m · s
1
(F(1,6) = 14.3,
P< 0.01, β= 0.8; F(1,6) = 69.6, P< 0.001, β= 1.0). Knee velocity
increased by 3.2 ± 0.3 m · s
1
after Dynamic training compared
with a 1.2 ± 0.2 m · s
1
increase after Isometric training, and a
0.4 ± 0.1 m · s
1
increase after Control (F(1,6) = 13.9, P= 0.009,
β= 0.9). The Control group did not significantly increase in
strike velocity more than Isometric or Dynamic training.
These results are summarised in Tables 5 and 6,and
Figure 3.
Electromyography
Significant increases in peak EMG amplitudes were measured
within both Isometric and Dynamic training groups for all
trials. During Jab trials, Isometric training elicited a 37%
increase in EMG amplitudes across all musculature on average,
Figure 2. Peak impact force during (a) Jab, (b) Cross, (c) JabCross Combination (Combo), (d) Knee strikes.
*statistically significant (P< 0.05) difference within training group. ** statistically significant (P< 0.05) difference between Isometric and Dynamic training
groups. *** statistically significant (P< 0.05) difference between Isometric and Control training groups. **** statistically significant (P< 0.05) difference between
Dynamic and Control training groups.
Table 5. Detailed statistics for strike velocity within each training group.
Trial
Stats (P-value, F-value, power)
Isometric Dynamic Control
Jab Pre F(1,3) = 0, P> 0.05,
power = 0
F(1,3) = 103.2, P= 0.006,
power = 0.9
F(1,3) = 0.4, P> 0.05,
power = 0.07Post
Cross Pre F(1,3) = 34.3, P= 0.01,
power = 0.8
F(1,3) = 140.9, P< 0.001,
power = 1.0
F(1,3) = 0.4, P> 0.05,
power = 0.07Post
Combo Pre F(1,3) = 4.4,
P> 0.05,
power = 0.4
F(1,3) = 16.5,
P= 0.03,
power = 0.7
F(1,3) = 10.6,
P= 0.05,
power = 0.7
F(1,3) = 34.7,
P= 0.01,
power = 0.8
F(1,3) = 0.3,
P> 0.05,
power = 0.06
F(1,3) = 1.0,
P> 0.05,
power = 0.09
Post
Knee Pre F(1,3) = 15.8, P= 0.03,
power = 0.7
F(1,3) = 12.6, P= 0.04 F(1,3) = 1.2, P> 0.05,
power = 0.1Post
8B. LEE AND S. MCGILL
with the largest increases (range: 5072%) in the left back
(LLAT, LUES, LLES) and left abdominal (LRA, LIO) musculature
(F(1,3) = 10.2120.5, P= 0.0010.5, β= 0.71.0). In comparison,
Dynamic training elicited a 35% average increase in overall
EMG signal during Jab trials, with the largest increases in the
left and right abdominal musculature (LRA, LEO, LIO, RRA, REO,
RIO; range: 3069%) (F(1,3) = 11.5140.1, P= 0.0010.04,
β= 0.71.0). Isometric training increased EMG amplitudes by
34% during Cross trials, with the largest increases (range:
3060%) occurring in the right back (RLAT, RUES, RLES) and
abdominal (REO, RIO) musculature (F(1,3) = 10.964.9,
P= 0.0010.05, β= 0.71.0). Dynamic training also increased
EMG amplitudes on average by 35%, with the greatest
increases (range: 3658%) in the right back (RLAT, RUES,
RLES) and gluteal (RGMax, RGMed) musculature (F
(1,3) = 15.834.0, P= 0.010.03, β= 0.70.9). Combo trials
experienced a 17% average increase in EMG amplitudes after
Isometric training, and 23% average increase after Dynamic
training. Isometric training yielded the greatest increases
(range: 1839%) in the right abdominal (RRA, REO, RIO) and
gluteal (RGMed) musculature (F(1,3) = 10.434.1, P= 0.010.05,
β= 0.70.9). Dynamic training had the greatest effect (range:
2640%) on right abdominal (RRA, REO, RIO) and gluteal
(RGMax, RGMed) musculature (F(1,3) = 16.4103.9, P= 0.005
0.03, β= 0.70.9). Knee trials experienced a 25% average
increase in EMG amplitudes after Isometric training, compared
with a 20% increase after Dynamic training. Isometric training
had the greatest effect (range: 2436%) on the left and right
abdominal (LEO, LIO, RRA, LEO, RIO) and right gluteal (RGMax,
RGMed) musculature (F(1,3) = 10.172.8, P= 0.0010.05,
Table 6. Detailed statistics for strike velocity between each training group.
Trial
Stats (P-value, F-value, power)
Iso/Dyn Dyn/Con Iso/Con
Jab Pre F(1,6) = 34.2, P< 0.001,
power = 1.0
F(1,6) = 8.7, P= 0.03,
power = 0.7
F(1,6) = 3.5, P> 0.05,
power = 0.5Post
Cross Pre F(1,6) = 6.0, P= 0.05,
power = 0.7
F(1,6) = 18.3, P= 0.008,
power = 0.9
F(1,6) = 13.9, P= 0.01,
power = 0.8Post
Combo Pre F(1,6) = 6.1,
P= 0.05,
power = 0.7
F(1,6) = 6.3,
P= 0.05,
power = 0.7
F(1,6) = 14.3,
P< 0.01,
power = 0.8
F(1,6) = 69.6,
P< 0.001,
power = 1.0
F(1,6) = 9.0,
P= 0.03,
power = 0.8
F(1,6) = 8.5,
P= 0.03,
power = 0.7
Post
Knee Pre F(1,6) = 6.0, P= 0.05,
power = 0.7
F(1,6) = 13.9, P= 0.009,
power = 0.9
F(1,6) = 9.8, P= 0.02,
power = 0.8Post
Figure 3. Peak strike velocity during (a) Jab, (b) Cross, (c) JabCross Combination (Combo), (d) Knee strikes.
*statistically significant (P< 0.05) difference within training group. ** statistically significant (P< 0.05) difference between Isometric and Dynamic training
groups. *** statistically significant (P< 0.05) difference between Isometric and Control training groups. **** statistically significant (P< 0.05) difference between
Dynamic and Control training groups.
JOURNAL OF SPORTS SCIENCES 9
β= 0.71.0), while Dynamic training had the greatest effect
(range: 1042%) on right abdominal (RRA, REO, RIO) and glu-
teal (RGMax, RGMed) musculature (F(1,3) = 14.584.3,
P= 0.0010.01 β= 0.81.0).
Comparing between training groups, Isometric and Dynamic
trainings increased peak EMG amplitudes more than Control for
almost all musculature in all trials but comparisons between
Isometric and Dynamic trainings revealed that some muscles
responded more to Isometric training, while other muscles
responded greater to Dynamic training. During Jab trials,
Isometric training increased overall peak EMG amplitudes simi-
larly to that of Dynamic training (37% vs. 35%) but left back
(LLAT, LLES), left abdominal (LRA, LIO), RLES, RIO, and RGMed
musculature experienced greater increases than with Dynamic
training (F(1,6) = 6.340.8, P=0.0010.05, β=0.70.8). Dynamic
training had a greater effect than Isometric training for left
gluteal (LGMax, LGMed), RUES, and RRA musculature (F
(1,6) = 9.334.2, P=0.0010.02, β=0.81.0). Isometric training
increased overall peak EMG amplitudes by 103% more than
Control on average, with significant increases in left back
(LLAT, LLES), left abdominal (LRA, LIO), LGMed, right back
(RUES, RLES), right abdominal (RRA, REO, RIO), and RGMed
musculature (F(1,6) = 6.013.8, P=0.010.05, β=0.70.8).
Dynamic training also increased overall peak EMG amplitudes
more than Control, on average 103% more, with left back (LLAT,
LLES), left abdominal (LRA, LIO), left gluteal (LGMax, LGMed),
and right back, abdominal, and gluteal (RUES, RRA, REO, RIO,
RGMed) musculature experiencing the greatest changes (F
(1,6) = 8.136.9, P=0.0010.03, β=0.80.9).
During Cross trials, Isometric and Dynamic trainings yielded
similar responses in EMG amplitude (34% vs. 35% overall aver-
age increase). Isometric training increased peak EMG ampli-
tudes greater than Dynamic training for left back and gluteal
(LLES, LGMax), right abdominal (REO, RIO), and right gluteal
(RGMax, RGMed) musculature (F(1,6) = 6.649.1, P=0.001
0.05, β=0.71.0); while Dynamic training had a greater effect
in left back (LLAT, LUES), left abdominal (LRA, LEO), and right
back and abdominal (RLAT, RUES, RLES, RRA) musculature (F
(1,6) = 9.050.1, P=0.0010.03, β=0
.81.0). Isometric training,
on average, elicited an overall increase 76% greater than
Control for all musculature (F(1,6) = 6.235.5, P=0.0010.05,
β=0.70.9), except for the RRA in which the Control group had
a greater response of increasing peak EMG amplitudes (F
(1,6) = 6.1, P=0.05,β= 0.7). Dynamic training elicited on
average a 77% greater increase in peak EMG amplitude than
Control for all musculature except for some gluteal (LGMax,
RGMax) and abdominal (REO) muscles (F(1,6) = 6.460.2,
P=0.0010.05, β=0.71.0). The Control group had a greater
effect on increasing peak EMG amplitudes than Dynamic train-
ing for REO muscles (F(1,6) = 7.0, P=0.04,β=0.8).
Combo trial performance revealed Dynamic training had a
25% overall greater effect on increasing peak EMG amplitudes
compared with Isometric training. Dynamic training had a
greater effect on some left and right back, abdominal and
gluteal (LUES, LEO, LGMax, RUES, REO, RIO, RGMax) musculature
(F(1,6) = 8.840.4, P=0.030.001, β=0.81.0); while Isometric
training increased LIO, LGMed, and RLAT EMG amplitudes
greater than Dynamic training (F(1,6) = 6.09.0, P=0.030.05,
β=0.70.8). Isometric training increased overall peak EMG
amplitudes 84% more than Control, with significant increases
in left abdominal (LEO, LIO), left gluteal (LGMax, LGMed), right
back (RLAT, RLES), right abdominal (RRA, RIO), and RGMed
musculature (F(1,6) = 10.035.9, P=0.0010.02, β=0.81.0);
while the Control group had a greater effect on than Isometric
training in the RUES musculature (F(1,6) = 6.3, P=0.05,β=0.7).
Dynamic training elicited a similar effect, yielding a 88% greater
increase in peak EMG amplitudes than Control, with significant
differences in response for some left back (LUES), left abdom-
inal (LRA, LEO), left gluteal (LGMax, LGMed), right back (RUES,
RLES), right abdominal (RRA, REO, RIO), and right gluteal
(RGMax, RGMed) musculature (F(1,6) = 6.039.1, P=0.001
0.05, β=0.71.0); while the Control group did not show any
greater effects than Dynamic training.
During Knee trials, Isometric training increased overall
peak EMG amplitudes 17% greater than Dynamic training
with significant changes in some left back, abdominal, and
gluteal(LLES,LEO,LGMax),rightback(RLAT,RLES),and
right gluteal (RGMAX, RGMed) musculature (F(1,6) = 6.0
13.8, P=0.010.05, β=0.70.9); while Dynamic training
had a greater effect on LGMed, RUES, and RIO musculature
(F(1,6) = 6.07.1, P=0.040.05, β=0.70.8). Isometric
training increased overall EMG amplitudes 99% more than
Control with significant differences in left back (LUES, LLES),
left gluteal (LGMax, LGMed), right back (RLAT, RUES, RLES),
right abdominal (RRA, REO, RIO), and right gluteal (RGMax,
RGMed) muscles (F(1,6) = 6.226.3, P=0.0050.05, β=0.7
1.0). Dynamic training also increased overall EMG ampli-
tudes 99% more than Control with significant changes in
theleftback(LUES,LLES),LIO,leftgluteal(LGMax,LGMed),
rightback(RUES,RLES),rightabdominal(RRA,REO,RIO),
and right gluteal (RGMax, RGMed) musculature (F(1,6) = 6.0
39.9, P=0.0010.05, β=0.71.0). The Control group did not
experience any changes in EMG amplitudes that were
greater than Isometric or Dynamic training.
Interestingly, an observed pattern of muscular activation
and relaxation was recorded in some muscles after Dynamic
training during all strike trials. Figure 5 exemplifies the left and
right back musculature before and after Dynamic training
during a Jab trial. The pretraining EMG pattern shows a typical
muscular profile during the strike; while after training, a dis-
tinct pattern of activation and relaxation (double peak)is
observed in the UES muscles.
Peak EMG amplitudes before and after Isometric and
Dynamic trainings and Control are summarised in Figure 4
with sample muscular activation patterns shown in Figure 5.
Discussion
The results suggest that the Isometric training protocol was
superior for enhancing impact force than the Dynamic proto-
col or Control, while the Dynamic training protocol was super-
ior in enhancing strike velocity compared with Isometric
training or Control groups. Interestingly, while Isometric and
Dynamic training groups both experienced increases in peak
EMG activity, the Dynamic training group was observed to
experience changes in the measured motor patterns involving
a shift from a typical single peak of activation to peaks of
muscular activation and relaxation.
10 B. LEE AND S. MCGILL
Figure 4. Peak EMG amplitudes during (a) Jab, (b) Cross, (c) JabCross Combination (Combo), (d) Knee strikes.
*statistically significant (P< 0.05) difference within training group. ** statistically significant (P< 0.05) difference between Isometric and Dynamic training
groups. *** statistically significant (P< 0.05) difference between Isometric and Control training groups. **** statistically significant (P< 0.05) difference between
Dynamic and Control training groups.
Figure 5. (a) Back (a, b), Abdominal (c, d), and Gluteal (e, f) EMG signals for the Jab strike before and after Dynamic core training. Note the difference in patternin
the UES (LUES, RUES) highlighted in Figure 5(a,b).
JOURNAL OF SPORTS SCIENCES 11
The use of EMG to investigate motor control strategies in
martial arts striking has grown in recent years (Machado, Osório,
Silva, & Magini, 2010; Neto & Magini, 2008; Quinzi, Camomilla,
Di Mario, Felici, & Sbriccoli, 2015; Sbriccoli et al., 2010;Sorensen,
Zacho, Simonsen, Dyhre-Poulsen, & Klausen, 1996), but investi-
gation of the use of core musculature in martial arts perfor-
mance is limited to 1 study the authors are aware of (McGill
et al., 2010). In processing EMG signals, a low pass filter cut-off
frequency of 2.5 Hz was selected to best translate the EMG
signal to that of the force generated by the torso musculature
(Brereton & McGill, 1998). However, this cut-off was determined
in participants who were not highly trained individuals.
Evidence exists that trained individuals are able to recruit a
greater proportion of motor units as well as a reduced electro-
mechanical delay in muscular activation. It is possible that the
participants in this study possessed this characteristic and their
faster response with less electromechanical delay would have
been better represented with a higher cut-off frequency than
an untrained population. However, work by McGill et al. (2010)
with elite MMA fighters investigated this issue and found that
EMG data processed at 3.5 and 4.5 Hz cut-off frequencies did
not affect the pattern of the EMG signal. Given that McGills
population of elite MMA fighters falls further away from the
untrained population than club Muay Thai fighters, the use of a
2.5 Hz cut-off frequency for low pass filtering appears justifiable.
Other limitations in the interpretation of this study include
possible day-to-day differences in EMG amplitude. For example,
skin/adipose thickness is known to influence EMG amplitude.
Participants did not change body mass more than 1 kg over the
trial suggesting this is a remote possibility. Further, the EMG
amplitudes were normalised which removes any influence of
differences in day-to-day absolute amplitudes. While there is no
method to compare Dynamic training and Isometric training to
create an equitable workload, we were very conscious of this
and tried to create an equitable volume in terms of duration
and load challenge. Finally, the numbers of participants were
relatively small given the availability of qualified and suitable
athletes. However, even with the limited numbers significance
in effect was found. This suggests that the effect size is prob-
ably larger than was found even with this smaller sample size.
There appears to be a link between enhanced impact force
and increases in torso stiffness. Evidence supports the notion
that Isometric core training enhances torso stiffness (Lee &
McGill, 2015) and effective mass, thus allowing the striker to
impart greater impact forces while minimising or stiffening
outany torso eccentric micro-movements. Stiffer core mus-
cles stabilising the spine appear to prevent energy leaksor
giving way(McGill, 2014 documents several examples). This
appears to be a viable candidate mechanism for enhancing
impact force. This general notion appears to be corroborated
with the increases in peak torso EMG activity, as increased
muscular activation and enhanced synchronicity of core/hip
muscular activation is linked to enhancements in core stiffness
(or what has been termed as a functional superstiffness,
Brown & McGill, 2009b; McGill, 2014). It is postulated that
enhanced strike velocity following Dynamic core training is
due to changes in muscle activation patterns (Figure 5).
Existing evidence links rates of muscular relaxation to creating
high-speed athletic movement; literature supports this claim
for martial arts striking (McGill et al., 2010), golf driving, and
sprinting (McGill, 2014). When comparing the differences
between the Isometric and Dynamic protocols, periods of
muscular relaxation in the Dynamic exercises appear to be
the main difference, particularly during the third block of
Dynamic exercises. While little evidence exists on how mus-
cular relaxation can be trained, except for work by Matveyev
(1981), the idea of training rates of muscular relaxation to
mimic this high force, high velocity motor pattern agrees
with the Principle of Dynamic Correspondenceexplained
by Verkhoshansky and Verkhoshansky (2011).
Typical of many studies, this investigation sheds new light
into the core training methods of Muay Thai practitioners, yet
spawns new questions to be answered in the future. Both
Isometric and Dynamic trainings enhanced separate properties
associated with powerful Muay Thai striking. While Isometric
training was superior in enhancing impact force and Dynamic
training was superior for enhancing strike velocity, investiga-
tion into how the 2 programmes performed together would
provide insight on enhancing both aspects. Further, what is
the role of increased EMG activity to the enhanced athletic
characteristics does increased EMG signal alone affect
impact force and strike speed, or do synchronisation of mus-
cular activation and altered patterns of activation/relaxation
play a larger role? Further, as stated above, little informed
insight exists in how muscular relaxation can be trained. This
study provided some evidence to suggest that Dynamic train-
ing can alter motor patterns to create activationrelaxation
cycles, but further investigation is needed to understand
mechanisms that will underpin eventual application.
Disclosure statement
No potential conflict of interest was reported by the authors.
Funding
This work was supported by Natural Sciences and Engineering Research
Council of Canada (NSERC).
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JOURNAL OF SPORTS SCIENCES 13
... In disciplines such as Muay Thai (Lee & McGill, 2017), boxing [18], mixed martial arts [19] , and other combat sports, it has been demonstrated that core stability significantly enhances sports performance. However, there remains a lack of clarity regarding how core stability affects performance in Taekwondo. ...
... In our study, we found a very strong negative correlation between SCST rating and execution time of the aerial phase of the wing kick. This suggests that the higher the SCST rating, the shorter the execution time of the aerial phase of the wing kick, which is similar to findings from other programs [31]. The comparative analysis clearly showed a significant difference between the two groups, and such a difference may have been key in influencing the scores. ...
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To win a taekwondo competition, more points must be scored, and the key to scoring points is to improve the motor performance of the kick. The wing kick is an offensive and defensive maneuver. Core stability appears to be important for improving athletic performance, but the specific relationship and effect of core stability on athletic performance in the aerial phase of taekwondo is unclear. The aim of this study was to investigate the relationship between core stability and athletic performance in taekwondo in order to provide appropriate theoretical support for training and to help coaches and athletes to improve athletic performance. A total of 16 subjects (height: 167.34±9.2 cm; weight: 61±8.96 kg; age: 24.7±3.25 years) were studied. Data were captured using 13 infrared cameras at 120Hz, kinematic and kinetic data were captured using a motivated motion capture system, and the data were exported to Visual3D in order to calculate the execution time of the aerial phase, the angular momentum of the left lower extremity, and MVC analysis of the EMG using EMG works. The core stability level of the subjects were measured using the Sahrmann Core Stability Test (SCST) to correlate with the other data, and then the subjects were grouped according to their core stability levels and the data from both groups were analyzed with t-tests. Results During the double fly lifting of aerial segments, SCST levels showed a very strong negative correlation with execution time (r= -0.739) and there was a statistically significant difference in execution time between high and low SCST levels (p < 0.001), and the desired negative correlation was also seen in lower limb angular momentum X-axis (thigh r= -0.6294, shank r= -0.536, foot r= -0.6175), especially in the X-axis. The left rectus femoris (LRF) data had greater activation in the low SCST group(p=0.0019*). Through this experiment, we found that athletes with high core stability had faster execution times, lower angular momentum, and higher core muscle activation. Therefore, we conclude that incorporating core stability training into taekwondo training has the potential to improve kicking performance.
... In summary, according to Thai trainers, training must be more rigorous than the fight itself. Thousands of kicks against punching bags and pads, as well as punches, are executed with great force (Lee & McGill, 2017). An important element of Muay Thai combat is the "clinch", which involves close quarters fighting with knee and elbow strikes, pulling the opponent's head, and taking them down. ...
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Muay Thai is a martial art that involves close combat, utilizing punches, elbows, knees, and kicks. The combat format is strictly full contact. The objective of this study is to show how training in Thai boxing influences the development of pain perception among practitioners. The study group consists of 20 male athletes, aged at least 15, with a minimum of 6 months of training experience. Measurement tools include a thermometer, blood pressure monitor, stopwatch, and a vessel with cold water. The research methods employed were the Modified Cuff Pressure Test and the Cold Pressor Test. The study found out that after a training session, the average pressure tolerance in the Modified Cuff Pressure Test increased, indicating a heightened pain perception. Specifically, the mean tolerance for arm pressure went from 255.0 mmHg before training to 270.3 mmHg after, and for leg pressure, it increased from 228.3 mmHg to 250.8 mmHg post-training. In the Cold Pressor Test, pain perception remained unchanged, with no significant variation in tolerance observed before and after training units. Training in Thai boxing may lead to a partial increase in tolerance to physical pain, especially immediately after a training session.
... The superficial muscles responsible for force transfer can only be better if the deep muscles responsible for stability are strong enough [5]. While for other sports such as handball, Muay Thai, Tennis and other sports where core stability can increase velocity at the distal [6,7,8]. But there is no research on the relationship between core stability and kicking velocity in taekwondo. ...
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To score in taekwondo competition requires faster kicking. Among the factors that influence kicking velocity, core stability is important, but the relationship between core stability and kicking velocity in taekwondo is unclear. The aim of this study was to investigate the association between core stability and foot segmental COM velocity at the moment of kick. A total of 13 taekwondo instructors (gender: male, height: 172.6±7.3 cm, weight: 64.3±11.78 kg, age: 29±4 years) participated in this study. The center of mass velocity of the left foot segment at the moment of the kick and the level of core stability was measured using the Sahrmann core stability test. During the Naraechagi, the velocity of the foot segment COM relative to the laboratory origin at the moment of the aerial phase kick was positively correlated in the forward and backward directions X-axis. Moderate correlation in the left and right direction Z-axis. Very strong correlation in the up and down direction Y-axis. Through the current experiment, we found a strong correlation between core stability and kicking speed in the forward and backward and up and down directions. Therefore, we believe that adding core stability training to taekwondo training has the potential to increase kicking speed.
... Squat strength is deemed a necessity for striking performance, punches are initiated at the rear leg which producing forces which transmits through the body, with high importance of the front leg displaying muscle isometric strength to propel contralateral force through the body (27,33,34). With the transmutation of force produced from the lower limbs, transmitted through the torso, and expelled onto the upper limbs (3,23) squat strength is shown to be essential to producing higher impact on punches. ...
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BLUF Thai Boxers display high levels of strength and power that correlate to striking performance; however, programming should be aimed at both the aerobic and anaerobic systems to be successful. ABSTRACT The purpose of this study was to observe and identify the physiological profiles of competitive Muay Thai athletes, to further understand what is required to be successful. Muay Thai bouts are set in differing formats, with timings of 3 x 2 minutes, 3 x 3 minutes or 3 x 5 minutes in duration dependant on weight category, fighter experience and tournament rules, with a 1-minute restorative period in between rounds. 24 Muay Thai fighters (21 males, 3 females; age: 26 years ± 6; stature: 1.75m ± 0.11; body mass: 76.30kg ± 16.22; body fat %: 12.88 ± 3.35), with a minimum of five years Muay Thai training and two years competitive experience (20 bouts ± 5) participated in the study. Participants completed a battery of physiological measurements, along with a series of strike performance measures. Correlation coefficients were used to assess the relationship between strike performance and physiological test performance. All striking performances apart from front hand Jab had a large correlation to pull ups, with back squats demonstrating both large and very large correlations with all strikes performed. Jab, rear hand cross and roundhouse strikes identified large correlations with reactive strength index. Right hook predictor variables are able to predict performance, F(6,17) = 4.754, p=0.005. The R 2 value (.792) suggests the model can explain 63% of the variance in right hook performance. Analysis of the coefficients showed the predictor variable of relative-bench press had a positive and significant influence on right hook impact power (B=2123.15, t = 2.402, p=0.028). Within the fight camp, fighters should be trained with a mixture of aerobic and anaerobic conditioning, with emphasis on strength and explosive strength.
... Increasing the mass behind a strike can be accomplished by acquiring more muscle mass through workout regimens, or by increasing muscle fiber recruitment and/or using larger muscle groups while delivering a strike (Pinto Neto et al., 2007). For example, instead of relying only on the muscles of the arm, some athletes also activate their core musculature to leverage their entire body mass to deliver more powerful strikes to an opponent (e.g., McGill et al., 2010;Lenetsky et al., 2015;Lee & McGill, 2016). When it comes to increasing strike velocity, however, there is paradoxical relationship between velocity and force that athletes face when punching or kicking: when muscles contract, they 2 IJKSS 11(2):1-10 become stiff and the velocity of the movement decreases (McGill, 2011). ...
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Background: Playing the drum kit is a physically and cognitively demanding task, and skilled drummers share many such attributes with elite athletes. The ‘double pulse’ muscle activation (DPMA) pattern is a motor control strategy that has been observed in athletes of sports involving ballistic movements (e.g., baseball, golf, Mixed Martial Arts), and is believed to function to increase force transfer to the target. Objective: This study examined the muscle activation patterns of highly skilled drummers for evidence of a DPMA during high-velocity cymbal crashes. Methods: Five drummers were instrumented with electromyography electrodes on the right latissimus dorsi, triceps brachii, erector spinae, rectus abdominis, deltoideus posterior (DP), teres major, extensor carpi radialis, and flexor carpi ulnaris muscles. Six trials of data were collected, including a resting baseline, three maximum voluntary exertions (MVE) consisting of maximal effort cymbal crashes, a drumming pattern that included multiple crashes, and a ‘free-play’ trial. Results: The DPMA waveform was observed in all trials, but only those observed during the MVE trials were confirmed to coincide with the crashing movement via video analysis. The DP muscle – which functions to extend the shoulder joint to crash the stick on to the cymbal – exhibited confirmed DPMAs the most frequently. Conclusion: The extent to which drummers use the DPMA to produce high-velocity cymbal crashes within authentic playing conditions is inconclusive and needs further examination. Future study of the DPMA phenomenon in drummers would benefit from the addition of 3-dimensional motion capture to further understand the purpose of the muscle contractions of the DPMA.
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Objective: This review examined the influence of anthropometric characteristics, such as body height (BH) and body mass (BM), on the impact of punches in striking-combat sports. Despite their perceived importance for combat strategy, the relationship between these characteristics and punch impact remains unclear. Methods: We included experimental, quasi-experimental and cross-sectional studies. The search was conducted on 30 August 2024, in three databases. The review analyzed 23 studies involving 381 participants (304 men, 30 women, 47 participants of unknown gender). Various instruments were used in the included studies, including ten instruments used to measure impact force and two instruments used to measure impact power. Results: Impact force ranged from 989 ± 116.76 to 5008.6 ± 76.3 N, with rear-hand straight punches and rear-hand hooks producing the greatest force. The PowerKube, a device specifically designed to measure punch impact power, revealed that the rear-hand straight punch generated the highest power, ranging from 15,183.27 ± 4368.90 to 22,014 ± 1336 W. While higher BM categories were associated with stronger punches, BM alone was not the only predictor. Other factors, such as technique, gender, and sport type, also played roles. The relationship between BH and punch impact showed mixed results. Conclusions: The data suggest that while higher BM categories are associated with greater punch impact, BM is not the only determining factor. The relationship between BH and impact also showed mixed results, with no clear association found. The review highlights the lack of a “gold standard” instrument for evaluating punch impact.
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Background: Pushing isometric muscle actions (PIMA) are regularly utilized to evaluate strength, fatigue, and neuromechanical aspects. Holding isometric muscle actions (HIMA) are largely unknown, although practitioners prescribe them in rehabilitation and performance contexts. The lack of knowledge and consensus in research on the distinction between two isometric types and limited scientific backing makes appropriate use in clinical and performance contexts difficult. Objective: To gather research directly comparing PIMA and HIMA, and to summarize and synthesize findings. We also aimed to identify potential practical applications for both tasks. Lastly, we highlight existing gaps in the literature and propose directions for future research. Methods: CINAHL, Embase, MEDLINE, PubMed and Web of Science databases were searched for peer-reviewed articles comparing PIMA and HIMA in humans. Risk-of-bias and study quality were assessed via established assessments for quasi-experimental studies and funnel plots, respectively. Findings were synthesized where possible, with meta-analyses and meta-regressions performed on time-to-task-failure (TTF), ratings of perceived exertion (RPE), heart rate (HR), and mean arterial pressure (MAP). Results: Fifty-four studies (publication year = 2012.9 ± 6.9; 1995-2024) were identified (N=856 participants; ~29.5 ± 10.1 years). Thirty-five included performance parameters (e.g., TTF), 45 examined neurological outputs (e.g., electromyography (EMG), electroencephalography), and 14 explored cardiovascular or metabolic (e.g., glucose uptake, oxygenation) variables. Meta-analysis of 23 studies revealed consistently longer TTF for PIMA vs HIMA at the same absolute intensity (n = 407; g = -0.74, p < 0.001), except for two studies examining axial muscles (g = 1.78-3.59, p < 0.001). Meta-analyses of 6-11 studies detected no absolute differences in HR, MAP, or RPE (n = 136-194; g = -0.11 to 0.18, p = 0.07-0.96), except for RPE at 50% of TTF being greater during PIMA (n = 164; g = -0.31, p = 0.01). PIMA mostly showed higher force fluctuations, discharge rates, D1-inhibition and peak torque, while HIMA indicated higher heteronymous facilitation, EMG burst rates, interspike interval variation, muscular glucose uptake, and faster increases in force/position fluctuations, EMG amplitude, RPE, HR, and MAP. Findings on muscle activation were mixed. HIMAs showed fewer neurological alterations during experimental joint pain. Conclusions: Evidence suggests distinguishing two types of isometric muscle action indicating more complex control strategies for HIMA than PIMA. Findings revealed similarities to anisometric actions, suggesting that the control strategies of HIMA and PIMA resemble the ones for muscle lengthening and shortening, respectively. HIMAs could provide a time-efficient approach for inducing musculoskeletal, neural, and cardiovascular adaptations in rehabilitation. PIMA may be beneficial for prolonged activation and agonist neuromuscular adaptations. Methods varied widely across studies, making additional meta-analyses impossible. More consistent methodology and data reporting are recommended. Randomized controlled trials are required to confirm the use of PIMA vs HIMA in clinical or performance contexts. The knowledge of both isometric types should be implemented in research and education. Registration: The original protocol was prospectively registered at the National Institute of Health Research PROSPERO (CRD42024530386).
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The main issue addressed here is the paradox of muscle contraction to optimize speed and strike force. When muscle contracts, it increases in both force and stiffness. Force creates faster movement, but the corresponding stiffness slows the change of muscle shape and joint velocity. The purpose of this study was to investigate how this speed strength is accomplished. Five elite mixed martial arts athletes were recruited given that they must create high strike force very quickly. Muscle activation using electromyography and 3-dimensional spine motion was measured. A variety of strikes were performed. Many of the strikes intend to create fast motion and finish with a very large striking force, demonstrating a "double peak" of muscle activity. An initial peak was timed with the initiation of motion presumably to enhance stiffness and stability through the body before motion. This appeared to create an inertial mass in the large "core" for limb muscles to "pry" against to initiate limb motion. Then, some muscles underwent a relaxation phase as speed of limb motion increased. A second peak was observed upon contact with the opponent (heavy bag). It was postulated that this would increase stiffness through the body linkage, resulting in a higher effective mass behind the strike and likely a higher strike force. Observation of the contract-relax-contract pulsing cycle during forceful and quick strikes suggests that it may be fruitful to consider pulse training that involves not only the rate of muscle contraction but also the rate of muscle relaxation.