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Abstract

https://www.tandfonline.com/doi/full/10.1080/02640414.2014.924055 This study aimed to investigate the contributions of kinetic and kinematic parameters to inter-individual variation in countermovement jump (CMJ) performance. Two-dimensional kinematic data and ground reaction forces during a CMJ were recorded for 18 males of varying jumping experience. Ten kinetic and eight kinematic parameters were determined for each performance, describing peak lower-limb joint torques and powers, concentric knee extension rate of torque development and CMJ technique. Participants also completed a series of isometric knee extensions to measure the rate of torque development and peak torque. CMJ height ranged from 0.38 to 0.73 m (mean 0.55 ± 0.09 m). CMJ peak knee power, peak ankle power and take-off shoulder angle explained 74% of this observed variation. CMJ kinematic (58%) and CMJ kinetic (57%) parameters explained a much larger proportion of the jump height variation than the isometric parameters (18%), suggesting that coachable technique factors and the joint kinetics during the jump are important determinants of CMJ performance. Technique, specifically greater ankle plantar-flexion and shoulder flexion at take-off (together explaining 58% of the CMJ height variation), likely influences the extent to which maximal muscle capabilities can be utilised during the jump.
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Journal of Sports Sciences 32, 1805-1812, 2014
Determinants of countermovement jump performance: a kinetic and kinematic
analysis
1Stuart McErlain-Naylor, 1Mark King, 1Matthew T G Pain
1School of Sport, Exercise and Health Sciences, Loughborough University, Leicestershire, LE11 3TU, UK
ABSTRACT
This study aimed to investigate the contributions of kinetic and kinematic parameters to
inter-individual variation in countermovement jump (CMJ) performance. Two-dimensional
kinematic data and ground reaction forces during a CMJ were recorded for 18 males of
varying jumping experience. Ten kinetic and eight kinematic parameters were
determined for each performance, describing peak lower-limb joint torques and powers,
concentric knee extension rate of torque development, and CMJ technique. Participants
also completed a series of isometric knee extensions to measure rate of torque
development and peak torque. CMJ height ranged from 0.38 0.73 m (mean 0.55 ± 0.09
m). CMJ peak knee power, peak ankle power, and take-off shoulder angle explained
74% of this observed variation. CMJ kinematic (58%) and CMJ kinetic (57%) parameters
explained a much larger proportion of the jump height variation than the isometric
parameters (18%), suggesting that coachable technique factors and the joint kinetics
during the jump are important determinants of CMJ performance. Technique, specifically
greater ankle plantar-flexion and shoulder flexion at take-off (together explaining 58% of
the CMJ height variation), likely influences the extent to which maximal muscle
capabilities can be utilised during the jump.
Keywords: countermovement jump, kinetics, kinematics, technique, rate of torque development
INTRODUCTION
The countermovement jump (CMJ) is a key performance requirement in many
sports. Research has shown positive relationships between lower-limb strength and
power measures and CMJ performance (Ashley & Weiss, 1994; Nuzzo, McBride,
Cormie, & McCaulley, 2008; Sheppard et al., 2008; Wisløff, Castagna, Helgerud,
Jones, & Hoff, 2004). However, further research is needed to explain quantitatively
the relative contributions of kinetic and kinematic variables to this movement. Of the
kinetic determinants, greater rate of force or torque development has frequently been
associated with increased CMJ performance (De Ruiter, van Leeuwen, Heijblom,
Bobbert, & De Haan, 2006; Marcora & Miller, 2000; McLellan, Lovell, & Gass, 2011;
Thompson et al., 2013). Both rate of force development and rate of torque
development measure the capabilities of skeletal muscle to rapidly generate muscle
forces and for the purposes of the present study will be referred to as rate of torque
development. Furthermore, it seems that the maximum force-dependent, post-50
ms, rate of torque development is more strongly related to CMJ height than the
earlier, neurally-mediated rate of torque development (Tillin, Pain, & Folland, 2013).
There are discrepancies among the results of the few studies investigating
ankle, knee and hip joint contributions during the CMJ. Hubley and Wells (1983)
found the greatest contributor to be the knee joint (49% of the total positive work),
whilst Fukashiro and Komi (1987) found it to be the hip joint (51%). More recently,
Vanezis and Lees (2005) obtained values (30% at the knee and 42% at the hip) that
were in closer agreement with Fukashiro and Komi (1987) than with Hubley and
Wells (1983). A novel finding by Vanezis and Lees (2005) was a negative
relationship between hip work and knee work, indicating a technique difference
between participants. The authors suggested that this difference could account for
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previous discrepancies in the literature, implying that technique determines the
relative contribution of different lower-limb joints. The inclusion of an arm swing
increased jump height by approximately 10 cm, supporting previous arm swing-
induced performance improvements (Feltner, Fraschetti, & Crisp, 1999; Shetty &
Etnyre, 1989). Likely contributors to this effect include the increase in work done at
the hip joint (Hara, Shibayama, Takeshita, & Fukashiro, 2006; Lees, Vanrenterghem,
& De Clercq, 2004) and maximised pre-takeoff mass centre displacement (Cheng,
Wang, Chen, Wu, & Chiu, 2008; Harman, Rosenstein, Frykman, & Rosenstein, 1990;
Payne, Slater, & Telford, 1968) in jumps with an arm swing. Simulation studies of
squat jumping show the augmented hip work to be due to a slowing of hip extension
enabling the musculature to work on a more favourable region of the force-velocity
curve (Blache & Monteil, 2013; Cheng et al., 2008; Domire & Challis, 2010).
Approximately one third of the arm swing related performance improvement results
from the work and energy induced at the shoulder joint (Domire & Challis, 2010).
Countermovement depth has also been linked to CMJ performance. Moran and
Wallace (2007) found that increasing the knee joint range of motion from 70° to 90°
resulted in a 17% improvement in CMJ height. Similarly, high ankle dorsi-flexion
range of motion has been shown to contribute to CMJ performance in men but not
women (Georgios, Fotis, Thomas, Vassilios, & Iraklis, 2007). Simulation studies
have shown an increase in squat depth to improve squat jump performance due to
an increase in time to develop joint torques (Bobbert, Casius, Sijpkens, & Jaspers,
2008; Domire & Challis, 2007). Proposed mechanisms for the benefit of the
countermovement phase in a CMJ include the development of active state prior to
concentric action (Bobbert, Gerritsen, Litjens, & van Soest, 1996; Bobbert & Casius,
2005), tendon elastic recoil (Alexander, 1995), and the enhancement of subsequent
force following muscle stretch (Edman, Elzinga & Noble, 1978).
Few researchers have compared kinetic and kinematic CMJ determinants.
Vanezis and Lees (2005) concluded that kinematic technique factors were less
important than muscle capabilities, although their technique analysis was limited to
the timing of the lowest vertical mass centre position and the use (or not) of an arm
swing. An increase in strength does not always result in a subsequent performance
improvement (Clutch, Wilton, McGown, & Bryce, 1983), perhaps due to the need to
adapt coordination following strength gains (Bobbert & van Soest, 1994). Supporting
the importance of appropriate technique utilisation, Luhtanen and Komi (1978)
reported that well-trained participants were able to utilise only 76% of the available
mechanical energy during a CMJ but that optimal coordination could increase this to
84%. It is evident that in order to gain a broad understanding of the determinants of
CMJ performance, it is necessary to study both kinetic and kinematic variables.
If the findings of this study are to be practically applicable when considering
progression from poor to good countermovement jumping ability then it is important
that variables contributing to the difference between good and poor jumpers are
identified. This necessitates the recruitment of a heterogeneous ability range to the
sample population so that the effects of variability in each of the kinetic and kinematic
variables can be observed. The purpose of the present study is therefore to quantify
the relative contributions of these factors in order to identify the most important
determinants of CMJ height.
METHODS
Eighteen physically active males (21.2 ± 2.2 years, 1.80 ± 0.08 m, 78.1 ± 9.2
kg, mean ± SD) participated in this investigation. Participants with large variation in
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jumping experience were selected so as not to distort the importance of individual
variables. The testing procedures were explained to each participant and informed
consent was obtained in accordance with the Loughborough University Ethical
Advisory Committee.
Participants attended two laboratory testing sessions: 1) isometric knee
extension measurement; 2) anthropometric and CMJ measurement. They were
required to refrain from strenuous physical activity for 36 hours prior to each session.
The knee extensor contractile properties of the dominant leg were tested using a
dynamometer (Con-Trex; CMV Aargau, Switzerland; hip angle 100°; frequency 512
Hz). Following dynamic stretching and submaximal warm up trials of incremental
intensity, isometric unilateral knee extension torque was measured at five angles
(15°, 30°, 45°, 60°, 75°; indicated a fully extended leg) in a randomised order.
Two trials were recorded at each angle, separated by 2 min rest: a 5 s maximal
voluntary contraction; then a measure of rate of torque development, with the
participant instructed to increase their knee extension torque as fast as possible
(Sahaly, Vandewalle, Driss, & Monod, 2001). The participants rested for 3 min
between each knee angle. The peak isometric knee extension torque was identified
as the highest of the angle-specific peak torques. The rate of torque development
trial at the angle corresponding to peak isometric torque was used to obtain the rate
of change of joint torque in 50 ms intervals (RTD0-50, RTD50-100, RTD100-150) from 0-
150 ms after the onset of contraction (identified manually; Tillin, Jimenez-Reyes,
Pain, & Folland, 2010). This enabled the investigation of the earlier agonist neural
drive dominated and later maximal voluntary torque dominated rate of torque
development (Andersen & Aagaard, 2006; Tillin, Pain, & Folland, 2012). All isometric
parameters were normalised to body mass.
For the CMJ measurement, thirty-eight 14 mm retro-reflective markers were
attached to each participant, positioned over bony landmarks. The metatarso-
phalangeal, ankle, knee, shoulder, elbow and wrist joint centres were calculated from
a pair of markers placed across the joint so that their mid-point coincided with the
joint centre, similarly to Ranson, King, Burnett, Worthington, and Shine (2009). The
centre of the neck was defined as the midpoint between two parkers positioned over
the sternoclavicular notch and the C7 vertebra. The centre of the head was defined
as the average position of four markers and the hip joint centres were calculated from
four markers placed over the left and right anterior and posterior superior iliac spine
(Davis, Õunpuu, Tyburski, & Gage, 1991). Participants were given the chance to
perform a self-selected warm-up and to practice before performing three maximal
CMJs using a natural technique of their selection, including arm swing. They were
permitted to rest between trials for as long as they felt necessary, with a minimum
rest period of 15 s imposed (Read & Cisar, 2001). Trials were recorded using a 17
camera (M2 MCam) Vicon Motion Analysis System (OMG Plc, Oxford, UK) operating
at 480 Hz. Ground reaction forces were measured using an AMTI force platform
(600 x 400 mm, 960 Hz).
The CMJs were manually labelled and processed and all data were
synchronised in Vicon’s software. Two-dimensional position data were used, with the
assumption of negligible movement in the medio-lateral plane. All joint centre
trajectories were filtered using a recursive fourth-order low-pass Butterworth filter
with a cut-off frequency of 6 Hz determined based on a residual analysis and
qualitative evaluation of the data (Winter, 1990). Unilateral joint centre positions
were assumed to represent the bilateral location and the errors in jump height and
peak joint torques caused by this assumption were calculated for one participant.
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These were found to be less than 1%, with the error in mass centre displacement
and joint torques remaining small throughout the movement.
Subject-specific segmental inertia parameters were computed from
anthropometric measurements using Yeadon’s (1990) geometric inertia model of the
human body. The average centre of mass height during the approximately 2 s period
of stationary standing prior to the jump was defined as zero displacement and thus
the CMJ height was determined as the maximum vertical mass centre displacement,
with the highest jump for each participant used for further analysis. Inverse dynamics
was used to obtain body mass normalised peak ankle, knee and hip net joint torques
and powers, with extension torques presented as positive. In order to provide
methodological consistency with the isometric rate of torque development and
facilitate the investigation of different time periods during knee extension, CMJ rate of
torque development was computed from 0-200 ms of knee extension in 50 ms
intervals (CMJ RTD0-50, CMJ RTD50-100, CMJ RTD100-150, and CMJ RTD150-200). Eight
kinematic parameters were also defined: minimum absolute joint angles and those at
take-off for the ankle, knee, hip, and shoulder. Shoulder extension beyond the line of
the greater trochanter to glenohumeral joint was defined as negative, with flexion
forwards from this line positive.
All statistical analyses were performed within SPSS v.20 (SPSS Corporation,
USA). To address the aim of the study and identify which of the isometric, CMJ
kinematic, and CMJ kinetic (independent) variables best explained the variation in
CMJ height (dependent variable), forwards stepwise linear regressions were used.
Predictor variables included in these three regression models were put forward as
‘candidate’ variables to an overall regression model. Scatterplot and Pearson
Product Moment Correlation analyses revealed a significant (r = 0.68, P < 0.01)
quadratic relationship between CMJ RTD0-50 and CMJ height and thus an
exponentiation transformation was performed on CMJ RTD0-50, raising each value to
the power of two prior to its inclusion in the linear regression analyses. The
requirement for the inclusion of a parameter in the regression equations was P <
0.05. Similarly, regression models were rejected if coefficient 95% confidence
intervals included zero or if correlations, tolerance statistics, or variance inflation
factors showed any evidence of multicollinearity (Bowerman & O’Connell, 1990;
Draper & Smith, 1998; Field, 2013; Menard, 1995; Myers, 1990). To confirm the
normality of the standardised residuals in the regression models Shapiro-Wilk tests
for normality were performed. The P-values ranged from 0.22 to 0.88 indicating no
evidence against the assumption of normality of the residuals. The percentage of
variance in the dependent variable (CMJ height) explained by the independent
variable(s) in a regression was determined by Wherry’s (1931) adjusted R squared
value. This represents an attempt to estimate the proportion of variance that would
be explained by the model had it been derived from the population (young physically
active males) from which the sample was taken. To overcome the potential limitation
of stepwise regressions relying on a single best model, the explained variance for all
possible regressions with the same number of predictor variables as the stepwise
solution were determined for comparison. Pearson Product Moment correlation was
used to establish relationships, with a P-value < 0.05 indicating statistical
significance.
RESULTS
The eighteen males participating in this study achieved CMJ heights of 0.38 -
0.73 m (mean 0.55 ± 0.09 m). There was substantial variation in the isometric
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parameters (Table I) with a mean peak isometric knee extension torque of 3.62 ±
0.68 N∙m∙kg-1. Of the CMJ kinematic parameters (Table I), the shoulder showed the
largest variation, indicating a technique difference at this joint. Mean peak powers at
the ankle, knee, and hip were 18.00 ± 4.20 W∙kg-1, 22.02 ± 4.94 W∙kg-1, and 9.83 ±
3.54 W∙kg-1 respectively (Table I). The mean concentric CMJ rate of torque
development was negative for all four 50 ms intervals.
Table I. Summary of parameters
isometric
parameters
mean ±
SD
CMJ kinetic
parameter
mean ± SD
CMJ kinematic
parameter
mean ±
SD
peak torque
(N∙m∙kg-1)
3.62 ±
0.68
PT ankle (N∙m∙kg-1)
2.79 ± 0.40
minimum ankle angle
(°)
84 ± 9
RTD0-50
(N∙m∙kg-1∙s-1)
11.67 ±
8.12
PT knee (N∙m∙kg-1)
3.31 ± 0.62
minimum knee angle
(°)
81 ± 16
RTD50-100
(N∙m∙kg-1∙s-1)
18.96 ±
7.92
PT hip (N∙m∙kg-1)
2.20 ± 0.44
minimum hip angle (°)
75 ± 15
RTD100-150
(N∙m∙kg-1∙s-1)
10.84 ±
5.07
PP ankle (W∙kg-1)
18.00 ± 4.20
minimum shoulder
angle (°)
-67 ± 26
PP knee (W∙kg-1)
22.02 ± 4.94
TO ankle angle (°)
137 ± 12
PP hip (W∙kg-1)
9.83 ± 3.54
TO knee angle (°)
174 ± 14
CMJ RTD0-50
(N∙m∙kg-1∙s-1)
-0.93 ± 6.07
TO hip angle (°)
172 ± 5
CMJ RTD50-100
(N∙m∙kg-1∙s-1)
-4.75 ± 8.12
TO shoulder angle (°)
103 ± 37
CMJ RTD100-150
(N∙m∙kg-1∙s-1)
-1.18 ± 8.15
CMJ RTD150-200
(N∙m∙kg-1∙s-1)
-0.66 ± 7.14
Note: CMJ: countermovement jump; RTD0-50, RTD50-100, RTD100-150, RTD150-200: rate of torque development from
0-50, 50-100, 100-150, 150-200 ms (of concentric knee extension for the CMJ RTD); PT: peak torque; PP:
peak power; TO: take-off.
Figure 1. Predicted countermovement jump (CMJ) height against actual CMJ height for the overall
three parameter stepwise solution (Table II). 74% of the variation in CMJ height explained
by: CMJ peak knee power; take-off shoulder angle; CMJ peak ankle power. With a higher
percentage of the variation in CMJ height explained the closer the data points lie to the
dashed line y = x (predicted height = actual height).
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Table II. Regression equations predicting countermovement jump height from computed variables using stepwise
linear regression
95% confidence
intervals
parameter(s)
coefficient
lower
bound
upper
bound
P
percentage
explained
isometric regression
peak isometric knee
extension torque
0.064
0.002
0.127
0.045
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CMJ kinematic
regression
TO shoulder angle
TO ankle angle
0.0016
0.0007
0.0024
0.001
58
0.004
0.002
0.007
0.003
CMJ kinetic
regression 1
CMJ peak knee power
CMJ peak ankle power
0.011
0.005
0.017
0.002
57
0.008
0.001
0.016
0.032
CMJ kinetic
regression 2
CMJ peak knee torque
0.087
0.036
0.138
0.002
57
CMJ peak ankle power
0.009
0.002
0.017
0.018
overall regression
CMJ peak knee power
0.010
0.005
0.015
0.001
74
TO shoulder angle
0.001
0.0004
0.002
0.005
CMJ peak ankle power
0.008
0.002
0.014
0.010
Note: CMJ: countermovement jump; TO: take-off; CMJ kinetic regression 1: stepwise solution; CMJ kinetic
regression 2: alternative solution. P < 0.05 indicates a significant relationship.
The best individual predictor of CMJ height was peak power at the knee joint,
explaining 44% of the observed variation (P < 0.01). This increased to 74% with the
addition of one CMJ kinematic parameter (take-off shoulder angle) and a further CMJ
kinetic parameter (peak ankle power; Figure 1). Higher jumps were associated with
greater peak powers at the knee and ankle, and greater shoulder flexion at take-off.
The CMJ kinematic regression showed the shoulder angle at take-off to be the
greatest kinematic predictor of jump height (R2 = 0.26, P < 0.05). Greater shoulder
flexion and ankle plantar-flexion at take-off predicted greater jump heights (together
explaining 58% of the variation). Two CMJ kinetic parameters (peak knee power and
peak ankle power) explained 57% of the variation (Table II). Increases in these
parameters were associated with greater CMJ heights. Further analysis showed that
an alternative CMJ kinetic regression model including peak knee torque and peak
ankle power also explained 57% of the variation in jump height.
The peak isometric knee extension torque alone accounted for 18% of the jump
height variation (P < 0.05; Table II), with insufficient evidence to support the addition
of any further isometric parameters to the regression equation (i.e. P > 0.05). The
correlation between peak isometric knee extension torque and CMJ peak knee power
was non-significant (r = 0.267; P = 0.142), with only 7% of the variation in peak knee
power explained by peak isometric torque.
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DISCUSSION
The present study has identified the parameters that best explain CMJ height.
In particular, 74% of the performance variation can be explained using just three
parameters: CMJ peak knee power; take-off shoulder angle; and CMJ peak ankle
power. Two CMJ kinematic parameters (take-off shoulder angle; and take-off ankle
angle) explained 58% of the jump height variation, whilst two CMJ kinetic parameters
(peak knee power or peak knee torque; and peak ankle power) and one isometric
parameter (peak isometric knee extension torque) explained 57% and 18%
respectively.
The inclusion of peak power at the knee and ankle joints in the overall
regression model supports previous claims that CMJ performance is positively
associated with lower-limb power (Ashley & Weiss, 1994; Nuzzo et al., 2008;
Sheppard et al., 2008; Vanezis & Lees, 2005). The work-energy-power relationship
makes it inevitable that greater joint powers result in more positive work done and so
greater total body kinetic energy and mass centre vertical velocities at take-off. As
an indicator of maximal capabilities of the knee extensor musculature, a greater peak
isometric knee extension torque enables greater joint torques and powers to be
produced during the CMJ. However, whilst the inclusion of peak isometric torque in
the isometric regression furthers the existing evidence for a relationship between
strength and CMJ height (Ashley & Weiss, 1994; Sheppard et al., 2008; Wisløff et al.,
2004), CMJ peak knee power explained a much greater proportion of the
performance variation (44% versus 18%). Similarly, Young, Wilson, and Byrne
(1999) showed that CMJ height is more closely related to measures of speed-
strength qualities than maximum strength. Indeed the low R2 (0.07) and lack of
significant correlation between body mass normalised peak isometric torque and
CMJ peak knee power variables suggest it is not maximal muscle strength that
causes the strong relationships between CMJ kinetic variables and jump height.
Given that the isometric parameters explained only 18% of the variation and 58% can
be explained by CMJ kinematic parameters it seems likely that technique (kinematic
parameters) determines the extent to which the maximal muscle capabilities
(isometric parameters) can be utilised during the jump (to produce the CMJ kinetic
parameters). Indeed, Bobbert and van Soest (1994) showed that an increase in
muscle strength only improves CMJ performance if technique is adapted to the
specific muscle capabilities. Thus, both the technique used and the joint kinetics
during the jump are likely important determinants of CMJ height in the current sample
of participants, where jumping ability varied greatly (from 0.38 0.73 m).
Experienced jumpers would be expected to use similar, close to optimal, techniques
and thus muscle capabilities may distinguish between their performances, as
reported by Vanezis and Lees (2005).
The lack of significant finding relating to the initial, neutrally-mediated isometric
RTD0-50 is in agreement with Tillin et al. (2013) but not De Ruiter et al. (2006). It
seems likely that the countermovement phase of the jump diminishes the importance
of fast neural activation by enabling the development of an active state prior to the
onset of concentric muscle contraction and thus increasing the time available to
activate the musculature and to generate extension joint torques (Bobbert et al.,
1996; Bobbert & Casius, 2005). In the very early stages of knee extension, whilst the
total length of the knee extensor musculo-tendon units decrease, the contractile
elements may still be being stretched as the tendon begins its elastic recoil and so
knee extension begins with large eccentric muscle forces (Alexander, 1995). All of
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these factors reduce the importance of fast initial rate of torque development during
CMJs.
The association between later (post-50 ms) rate of torque development and
CMJ height is dependent on absolute maximal force (Tillin et al., 2013) and so with
peak isometric knee extension torque already included in the stepwise regressions,
the inclusion of the later isometric rates of torque development did not significantly
improve the prediction of jump height. Previous studies have used correlation
coefficients rather than stepwise regressions to assess the rate of torque
development-jump height relationship and so were not affected by this issue (De
Ruiter et al., 2006; Marcora & Miller, 2000; McLellan et al., 2011; Thompson et al.,
2013; Tillin et al., 2013). These assertions are further supported by a significant
correlation between peak isometric torque and RTD100-150 (r = 0.546; P = 0.01) in the
present study.
The significant quadratic relationship between CMJ RTD0-50 and CMJ height (r =
0.68, P < 0.01) was explained by a significant (r = -0.48, P < 0.05) negative
correlation between CMJ RTD0-50 (variable x) and the knee extension torque at
concentric onset (variable y). This relationship takes the form x + ay constant (i.e.
there is a trade-off between the two variables), with (x2 + y2) positively correlating to
CMJ height (r = 0.69, adjusted R2 = 0.45, P < 0.01). This (x2 + y2) relationship means
that the higher jumpers either produced high eccentric knee extension torques
(greater y; resulting in an apparent benefit of negative rates of torque development
as torque subsequently decreased during knee extension) or were able to maintain
their knee extension torque during early concentric contraction (greater x), with those
participants in the mid-range for both variables (neither high x nor high y) achieving
the lowest jump heights.
Despite the discussed benefits of the countermovement phase, the minimum
knee and ankle angles were not included in the stepwise solutions. This is in
contrast with previous findings that increased knee and ankle joint ranges of motion
result in greater jump heights (Georgios et al., 2007; Moran and Wallace, 2007).
Further analysis of individual subject data in the present study showed that the
highest jumper was the participant with the greatest knee flexion. In theory there is
no limit to the relationship between increased squat depth and increased squat jump
height (Domire & Challis, 2007); however, jumps from a deep squat are rarely
optimally coordinated due to a lack of practice with this technique. This same issue
is likely present in inexperienced countermovement jumpers and may explain why
the link between minimum knee angle and CMJ height was only observed in the best
performing participant.
Previous studies have simply compared jumps with and without an arm swing
(Feltner et al., 1999; Harman et al., 1990; Payne et al., 1968; Shetty & Etnyre, 1989;
Vanezis & Lees, 2005), whereas the present study investigated shoulder angles at
key points in the arm swing movement. Greater shoulder flexion at take-off was a
strong predictor of CMJ height, likely indicating greater use of the arm swing, and
thus a slowing of hip extension leading to greater work done at the hip as well as the
shoulder (Blache & Monteil, 2013; Cheng et al., 2008; Domire & Challis, 2010). Both
greater shoulder flexion and ankle plantar-flexion at take-off increase the ‘stretch
height’ and thus pre-takeoff displacement and both were included in the CMJ
kinematic regression. Because CMJ height was calculated relative to standing
position, pre-takeoff displacement was included and thus jump height may be
affected by anthropometric variables such as foot length. However, the degree to
which any anthropometric advantage is reflected in the stretch height is dependent
9
on technique such as shoulder flexion and ankle plantar-flexion. An analysis of
individual participant data suggests that the degree of ankle plantar-flexion and
shoulder flexion during the propulsion phase distinguishes the highest two jumpers
from the rest of the participants and explains the underestimation of their jump
heights by the CMJ kinetic and isometric parameter regression models. Exclusion of
these participants would increase the adjusted R2 for these two regressions to 0.66
and 0.40 respectively, illustrating the importance of recruiting a heterogeneous
sample so as not to overestimate the importance of individual factors in the
progression from poor to good countermovement jumping.
One limitation of the present study is the introduction of errors by any
movement outside of the sagittal plane, although this is expected to have been
negligible. Furthermore, isometric knee extensions were measured at five discrete
joint angles and so the true peak isometric torque is likely at an intermediate angle.
In a review by Jakobi and Chilibeck (2001) 5 out of 8 studies showed no bilateral
deficit in isometric knee extension. The effect is present, however, in explosive
voluntary contractions such as the isometric rate of torque development trials in this
study (Buckthorpe, Pain, & Folland, 2013). The potential implications of this deficit in
the present study are minor, with the application of unilateral measures to the
investigation of a bilateral performance task unlikely to distort the observed
relationships. The 74% of CMJ height variation explained by the overall three
parameter regression suggests that the important aspects of performance have been
identified. In particular, those wishing to improve their CMJ height should seek to
maximise power at the knee and ankle joints and utilise greater ankle plantar-flexion
and shoulder flexion. These results are likely to provide a valuable framework upon
which to base coaching and conditioning as athletes progress from poor to good
countermovement jumping. Future studies should continue to explore the interaction
between kinetic and kinematic factors, including joint ranges of motion and the
timings of muscle activations, possibly using methods beyond the scale of the current
study such as simulation modelling or electromyography. It is also important to
address whether these results are independent of anthropometric differences and
whether the same results are observed in a female population.
In conclusion, the purpose of the study was to quantify the relative contributions
of kinetic and kinematic parameters in order to identify the most important
determinants of CMJ performance. The findings suggest that both kinetic and
kinematic factors during the jump are important determinants of CMJ performance,
with technique influencing the extent to which maximal muscle capabilities can be
utilised during the jump. The study has revealed the importance of lower-limb joint
powers and previously underestimated, coachable technique factors including
greater ankle plantar-flexion during the jump and shoulder flexion during the arm
swing. Both the kinetic and kinematic variables during the jump explained a large
proportion of the performance variation and further research is needed to fully
understand the interactions between these two sets of factors.
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... Vertical jumps are one of the most popular tests of athletic performance for coaches and researchers alike (McMaster et al., 2014;Morin, 2019), and it has been reasoned that an individual's capacity to produce force at a high rate during isometric leg extensions or during vertical jumps is related to jump performance (McErlain-Naylor et al., 2014;Vanezis & Lees, 2005). Yet, studies that have directly examined relationships between the rate of ground reaction force development (RFD) during a vertical jump and the jump height achieved have produced conflicting results (Ebben et al., 2007;Laffaye & Wagner, 2013;McLellan et al., 2011). ...
... The model summary and variable coefficients for the final two steps for the sexes combined model can been seen in Tables 4 and 5, respectively. The adjusted R 2 value for the final step of the model indicates the predictors account for 63.8% of the variance in vertical jump height which is comparable to previously reported multiple regression models which attempted to predict vertical jump height without including power and impulse as predictors (Dowling & Vamos, 1993;McErlain-Naylor et al., 2014). It should be noted that the model does reflect some minimal multicollinearity for steps following the inclusion of the sex × weight interaction according to the high VIF values and low tolerance values for sex, weight, and the interaction variable. ...
... The more plausible conclusion is that the theoretical concept of a high rate of strength development in lower limbs is better captured by measures other than RFD. Specifically, peak power (Dowling & Vamos, 1993;McBride et al., 2010;McLellan et al., 2011;Peterson et al., 2006) and individual joint powers (McErlain-Naylor et al., 2014) are consistently shown to be strong predictors of vertical jump height that are related to the concept of high rate of strength development. Therefore, the current findings do not suggest that the concept of high rate of strength development is not important for vertical jumping or other athletic performances, rather that estimations of RFD may not be the best measures of this concept. ...
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Purpose: Many researchers and coaches hold that the ability to generate force rapidly is an important factor in athletic performance. This concept is often studied by analyzing the rate of ground reaction force development (RFD) during vertical jumps; however, many such studies disagree on whether estimates of RFD are true predictors of vertical jump height, have limited sample sizes, and have not employed multiple regression analysis. Therefore, the purpose of the study was to assess the utility of RFD as a predictor of vertical jump height. Methods: Forward sequential multiple regression models were performed using kinematic, kinetic, and demographic variables from a database of maximal countermovement vertical jumps collected via motion capture system from 2,258 NCAA Division I athletes. Results: Peak RFD was a significant bivariate predictor of vertical jump height (r = 0.408, p < .001). However, when other variables were included in the prediction model the partial variance in vertical jump height accounted for by peak RFD was nearly eliminated (r = -0.051, β = -0.051), but sex (r = 0.246, β = 0.94) and peak ground reaction force (r = 0.503, β = 1.109) emerged as predictors of partial variance in jump height. Furthermore, mediation analysis revealed the direct effect of peak RFD on vertical jump height was only 0.004. Conclusions: Multiple regression analysis enabled by a large sample size suggests Peak RFD may not be uniquely useful as a predictor of vertical jump height during maximal countermovement jumps.
... However, only a small effect in favor of PIST was observed when compared with CON. CIST might have resulted in greater improvement in force generation capability at a 90 o knee angle, which is also the common knee position adopted during the initiation of the propulsion phase of CMJ (28,30), because of greater volume of ISqt at that joint position over the 24-week period. ...
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Lum, D, Joseph, R, Ong, KY, Tang, JM, and Suchomel, TJ. Comparing the effects of long-term vs. periodic inclusion of isometric strength training on strength and dynamic performances. J Strength Cond Res XX(X): 000-000, 2022-This study compared the effects of including isometric strength training (IST) for consecutive 24 weeks (CIST) against a periodic inclusion (PIST) of this mode of training on strength and dynamic performances. Twenty-four floorball athletes (age: 23 6 2.7 years, stature: 1.74 6 2.08 m, and body mass: 72.7 6 14.4 kg) were randomly assigned to the control (CON), CIST, or PIST group. Athletes completed 20-m sprint, countermovement jump (CMJ), and isometric midthigh pull (IMTP) during pre-test and were tested on weeks 6, 12, 18, and 24. All groups performed a similar strength training program twice per week. However, 2 sets of squats were replaced with isometric squat in CIST for all 24 weeks but only on weeks 1-6 and 13-18 for PIST. A significant main effect for time was observed for 5-, 10-, and 20-m sprint time, CMJ height, peak force, peak power, time to takeoff , modified reactive strength index, IMTP peak force, relative peak force, and force at 200 milliseconds (p 5 ,0.001-0.037). Isometric strength training for 24 consecutive weeks resulted in greater improvement in 5-m sprint time than CON at week 24 (p 5 0.024, g 5 1.17). Both CIST and PIST resulted in greater improvements in 10-m sprint time than CON at various time points (p 5 0.007-0.038 and 0.038, g 5 1.07-1.44 and 1.18, respectively). Isometric strength training for 24 consecutive weeks and PIST resulted in greater improvements in 20-m sprint time than CON at week 6 (p 5 0.007 and 0.025, g 5 1.65 and 1.40, respectively). The results showed that the inclusion of IST resulted in greater improvements in sprint performance than CON but no significant difference in all measured variables with PIST.
... However, only a small effect in favor of PIST was observed when compared with CON. CIST might have resulted in greater improvement in force generation capability at a 90 o knee angle, which is also the common knee position adopted during the initiation of the propulsion phase of CMJ (28,30), because of greater volume of ISqt at that joint position over the 24-week period. ...
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... The countermovement soar (C.M.J.) is primarily used to degree the explosive energy of an athlete's lower frame. It has turn out to be one of the maximum regularly used exams by coaches and researchers to measure electricity within the lower limbs [3] indirectly. considering the fact that power is a important issue in many sports activities, and the C.M.J. is a easy, practical, and dependable measure of strength inside the lower limbs, it would look like an obvious preference as a tool for measuring and monitoring performance. ...
... Jump. Jumping performance is often utilized as a key indicator for lower-limb power, strength and physical ability with both healthy and athletic populations [4,72]. Improvements in energy production and storage during the stretch-shortening cycle may be related to the transition from eccentric to concentric phases during flywheel training [73]. ...
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... Las pruebas destinadas a evaluar la saltabilidad en deportistas son consideradas como una forma eficaz de determinar la potencia y las diferencias funcionales entre las extremidades inferiores, siendo utilizadas como factor de riesgo de lesiones musculoesqueléticas (12). La altura del salto es un buen predictor de la potencia muscular, y, por tanto, varios tipos de saltos verticales se han empleado como pruebas estandarizadas del rendimiento deportivo (13,14). ...
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Objetivo: el objetivo del estudio fue identificar la relación entre los resultados de las pruebas saltabilidad horizontal y vertical con la incidencia las lesiones musculoesqueléticas de miembros inferiores en futbolistas de un club de la liga profesional colombiana. Materiales y métodos: se realizó un estudio analítico, exploratorio, en 30 futbolistas de la nómina profesional del Club Deportivo Atlético Junior F.C. Al inicio de la temporada se evaluaron las características antropométricas, así mismo como la saltabilidad y asimetrías funcionales de las extremidades inferiores a través de pruebas de saltos verticales (CMJ y CMJs) y horizontales (3-Hop Test). El análisis consistió en la comparación los registros de las variables estudiadas entre los futbolistas con (lesionados n=11) y sin lesión (no lesionados n=19) en el transcurso del primer semestre de la temporada 2019. Resultados: en los hallazgos no se encontraron diferencias estadísticas entre los grupos en las características biológicas, antropométricas y de composición corporal (p>0,05). Derivado de los hallazgos en la saltabilidad vertical, no se observaron diferencias significativas en las asimetrías funcionales entre grupos (p>0,05), sin embargo, si se encontraron diferencias en las pruebas de saltabilidad horizontal entre lesionados y no lesionados (p<0,01). Conclusión: de este estudio podemos concluir que, en comparación a los futbolistas profesionales sin lesiones, se encontraron significativamente mayores asimetrías funcionales detectadas a través de la prueba de saltabilidad horizontal en los deportistas con lesión.
... Both Jalilvand et al. (2019) and McMahon et al. (2020) recorded the highest of three countermovement vertical jumps, performed with hands on hips to reduce the influence of arm swing magnitude (McErlain-Naylor, King, & Pain, 2014). Both studies measured average sprint velocity using a timing light system, recording the best of two (Jalilvand et al., 2019) or three (McMahon et al., 2020) attempts. ...
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Jump take-off momentum has previously been proposed as an alternative test to predict sprint momentum. This study used a data simulation to replicate and systematically investigate relationships reported in previous studies between body mass, vertical jump performance, and sprint performance. Results were averaged for 1000 simulated data sets in each condition, and the effects of various parameters on correlations between jump momentum and sprint momentum were determined. The ability of jump take-off momentum to predict sprint momentum is greatest under relatively high inter-individual variation in body mass and relatively low inter-individual variation in jump height. This is largely due to the increased emphasis on body mass in these situations. Even under zero or a small negative (r = -0.30) correlation between jump height and sprint velocity, the correlation between the two momenta remained very large (r ≥ 0.76) on average. There were no investigated conditions under which jump momentum was most frequently a significantly (p < 0.05) greater predictor of sprint momentum compared to simply using body mass alone. Furthermore, between-individual correlations should not be used to make inferences or predictions for within-individual applications (e.g., predicting or evaluating the effects of a longitudinal training intervention). It is recommended that any rationale for calculating and/or monitoring jump take-off momentum should be separate from its ability to predict sprint momentum. Indeed, body mass alone may be a better predictor of sprint momentum.
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The backward double integration method uses one force plate and could calculate jump height for countermovement jumping, squat jumping and drop jumping by analysing the landing phase instead of the push-off phase. This study compared the accuracy and variability of the forward double integration (FDI), backwards double integration (BDI) and Flight Time + Constant (FT+C) methods, against the marker-based rigid-body modelling method. It was hypothesised that the jump height calculated using the BDI method would be equivalent to the FDI method, while the FT+C method would have reduced accuracy and increased variability during sub-maximal jumping compared to maximal jumping. Twenty-four volunteers performed five maximal and five sub-maximal countermovement jumps, while force plate and motion capture data were collected. The BDI method calculated equivalent mean jump heights compared to the FDI method, with only slightly higher variability (2-3 mm), and therefore can be used in situations where FDI cannot be employed. The FT+C method was able to account for reduced heel-lift distance, despite employing an anthropometrically scaled heel-lift constant. However, across both sub-maximal and maximal jumping, it had increased variability (1.1 cm) compared to FDI and BDI and should not be used when alternate methods are available.
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Previous studies have examined the role of arm swing for various types of jumping technique, but none have been found to study about the gender differences in term of the role of arm swing on forward and backward jump. This study aimed to compare the jumping performance between male and female for forward and backward jump. Seven male and seven female subjects performed four trials of forward and backward jump with (FJA, BJA) and without arm swing (FJ, BJ) respectively. Qualisys Track Manager System, EEGO Sports, Visual3D and MATLAB software was used to record and analyze the performance. According to the result, the triceps brachii muscle is the most active muscle compared to other muscles during jumping. The normalized vGRF showed significant correlation with jump height when jumping forward and backward (p<0.01). The arm swing enhanced the jumping performance by increasing the jump height. Males demonstrated greater vGRF and jump height than females. When jump with arm swing, the left knee flexion angle of males increased whereas females decreased. These findings concluded there is different between males and females during jumping.
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Background Athletes with chronic ankle instability (CAI) are prone to recurrent ankle giving-way episodes due to impairments in the joint’s stress-shielding capacity. CAI can deteriorate athletes’ biomechanics and increase the risk of other lower limb injuries. One popular treatment for CAI is Kinesio tape (KT). The effects of lateral ankle support from KT application on different jump biomechanical characteristics such as kinetic, kinematic and electromyography variables have not been extensively studied.AimsThis study was designed to observe the impacts of ankle KT on lower limb biomechanics and muscle activation during a countermovement jump among athletes with CAI.Methods Thirty collegiate athletes with CAI performed three countermovement jumps before and after KT application around their shank and ankle. Kinematic variables included ankle, knee, and hip range of motion, angular velocity, and power. Kinetic variables included vertical ground reaction force, rate of force development, and peak power. Muscle activation was measured from lateral and medial gastrocnemius, tibialis anterior, and peroneus longus.ResultsKT decreased frontal plane ankle movement (P = 0.002) and peroneus longus activity (P = 0.045). Additionally, we observed a significant increase in jump height (P = 0.001), ankle plantar flexion ROM (P = 0.006), angular velocity of all lower limb joints (P < 0.05), vertical ground reaction force (P < 0.001), rate of force development (P < 0.001), peak power (P < 0.001), hip and ankle joint power (P = 0.001, and 0.021, respectively), and activity amplitudes of lateral gastrocnemius (P = 0.028) and medial gastrocnemius (P = 0.015). Conclusion Lateral ankle support using KT appears to decrease ankle ROM in the frontal plane and ankle stabilizer activity, suggesting KT may be efficient for supporting the lateral ankle during jumping. Moreover, KT could improve various kinematic and kinetic variables that resulted in better jump performance. It seems that ankle KT may be beneficial for protecting the joint while improving the performance.
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Fast bowling in cricket is an activity that is well recognised as having high injury prevalence and there has been debate regarding the most effective fast bowling technique. The aim of this study was to determine whether two-year coaching interventions conducted in a group of elite young fast bowlers resulted in fast bowling technique alteration. Selected kinematics of the bowling action of 14 elite young fast bowlers were measured using an 18 camera Vicon Motion Analysis system before and after two-year coaching interventions that addressed specific elements of fast bowling technique. Mann-Whitney tests were used to determine whether any changes in kinematic variables occurred pre- and post-intervention between those who had the coaching interventions and those who didn't. The coaching interventions, when applied, resulted in a more side-on shoulder alignment at back foot contact (BFC) (p = 0.002) and decreased shoulder counter-rotation (p = 0.001) however, there was no difference in the degree of change in back and front knee flexion angles or lower trunk side-flexion. This study has clearly shown that specific aspects of fast bowling technique are changeable over a two-year period in elite level fast bowlers and this may be attributed to coaching intervention.