Analysis of muscle activity in various performance levels of Ollie jumps in skateboarding: A pilot study

Abstract

Background: Correct mastering of a basic Ollie jump is essential for development of other jumps in skateboarding. In scientific literature we can find a lack of scientifically proved knowledge that describes the difference in muscular activity on various levels of this jump performance. Objective: The aim of this study was to characterize muscular activity in the basic skateboard Ollie jump and to compare this activity with a more difficult modification of the switchstance Ollie jump (the same jump but changed position of limbs). Methods: Ten men experienced in skateboarding for several years, aged 20.0 ± 4.6 years participated in the study (height 1.79 ± 0.05 m, body mass 71.5 ± 4.1 kg). All subjects performed 3 measured Ollie jumps and after that 3 switchstance Ollie jumps. In case of the last-mentioned front and back lower limbs are switched. The observation of muscular activity was carried out by the Delsys Trigno electromyography system. The jump was divided (after video records) into four phases: preparatory, take-off, flight-up and landing. Mean amplitude of muscle activity was measured in following muscles: tibialis anterior, gastrocnemius medialis, rectus femoris, semitendinosus and gluteus medius. Comparison of muscle activity during Ollie and switchstance Ollie was performed by the Wilcoxon test in Statistica. Results: Significantly greater activity (p < .05) was shown by gastrocnemius medialis and rectus femoris on the lower back limb during the preparatory phase of switchstance Ollie and by tibialis anterior and semitendinosus on lower front limb during the landing phase of Ollie. Conclusion: Results of our study suggest that in switchstance Ollie is increased muscle activity during preparation period on the back limb and movement control during landing. The skaters in this type of jump should move his/her centre of gravity from the tail to the centre of the skateboard and also he/she would produce adequate muscle activity also during the landing phase.

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41
skateboard jumps. Frederick, Determan Whittlesey,
and Hamill (2006) describe the ground reaction forces
during the Ollie jump, Determan, Frederick, Cox, and
Nevitt (2006) during the Kickflip jump. Although the
study by Crockett and Jensen (2007) includes monitor-
ing of muscle activity by electromyography (EMG), this
study is primarily concerned with the ratio of the number
of rebounds and speed of movement and comparison of
muscle activity during various skateboard jump perfor-
mances is missing.
The aim of this study was to compare muscle activity
in the basic skateboard jumps, the Ollie and switchstance
Ollie.
Methods
Subjects
The experiment involved 10 men without health prob-
lems aged 20.0 ± 4.6 years with height 1.79 ± 0.05 m
Introduction
Skateboarding is one of the most popular extreme
sports in recent years (Kuleshov, 2010). This sport is a
recreational activity, professional sport and for a lot of
young people it is a lifestyle as well (Fountain, & Mey-
ers, 1996; Keilani et al., 2010; Rethnam, Yesupalan, &
Sinha, 2008).
Mastery of rigorous technique in basic skateboard
jumps is a very important aspect of success in this
sport (Kane, 1989). In skateboarding, as in relatively
young sport, there are currently missing evidence based
training recommendations. The scientific literature
describes mainly the dynamic characteristics of the
* Address for correspondence: Michal Vorlíček, Institute of
Active Lifestyle, Faculty of Physical Culture, Palacký Uni-
versity, tř. Míru 115, 771 11 Olomouc, Czech Republic.
E-mail: michal.vorlicek@upol.cz
Analysis of muscle activity in various performance levels of Ollie jumps
in skateboarding: A pilot study
Michal Vorlíček*, Zdeněk Svoboda, and Markéta Procházková
Faculty of Physical Culture, Palacký University, Olomouc, Czech Republic
Copyright: © 2015 M. Vorlíček et al. This is an open access article licensed under the Creative Commons Attribution License
(http://creativecommons.org/licenses/by/4.0/).
Background: Correct mastering of a basic Ollie jump is essential for development of other jumps in skateboard-
ing. In scientific literature we can find a lack of scientifically proved knowledge that describes the difference in
muscular activity on various levels of this jump performance. Objective: The aim of this study was to characterize
muscular activity in the basic skateboard Ollie jump and to compare this activity with a more difficult modification
of the switchstance Ollie jump (the same jump but changed position of limbs). Methods: Ten men experienced in
skateboarding for several years, aged 20.0 ± 4.6 years participated in the study (height 1.79 ± 0.05 m, body mass
71.5 ± 4.1 kg). All subjects performed 3 measured Ollie jumps and after that 3 switchstance Ollie jumps. In case of
the last-mentioned front and back lower limbs are switched. The observation of muscular activity was carried out by
the Delsys Trigno electromyography system. The jump was divided (after video records) into four phases: prepara-
tory, take-off, flight-up and landing. Mean amplitude of muscle activity was measured in following muscles: tibialis
anterior, gastrocnemius medialis, rectus femoris, semitendinosus and gluteus medius. Comparison of muscle activity
during Ollie and switchstance Ollie was performed by the Wilcoxon test in Statistica. Results: Significantly greater
activity (p < .05) was shown by gastrocnemius medialis and rectus femoris on the lower back limb during the prepara-
tory phase of switchstance Ollie and by tibialis anterior and semitendinosus on lower front limb during the landing
phase of Ollie. Conclusion: Results of our study suggest that in switchstance Ollie is increased muscle activity during
preparation period on the back limb and movement control during landing. The skaters in this type of jump should
move his/her centre of gravity from the tail to the centre of the skateboard and also he/she would produce adequate
muscle activity also during the landing phase.
Keywords: electromyography, kinesiology, training, skateboarding
Acta Gymnica vol. 45, no. 1, 2015, 41–44
doi: 10.5507/ag.2015.006

42 M. Vorlíček et al.
and body weight 71.5 ± 4.1 kg. All measured persons
had at least four years of experience with skateboard-
ing and good jump technique of Ollie and its modifica-
tion, the switchstance Ollie.
The methods and technical equipment
For analysis of muscle activity a wireless surface electro-
myography system Delsys Trigno (frequency 200 Hz,
Delsys, Boston, MA, USA) was used. EMG recording
was synchronized with a video recording (frequency
50Hz, camera Sony DCR-TRV, Sony, Tokyo, Japan).
The measurement process
The study was approved by the Ethics Committee of
the Faculty of Physical Culture, Palacký University,
Olomouc. At the beginning of measurement subjects
signed informed consent and had a few minutes to test
the basic jumps at the place of measurement. Then
their skin was shaved and cleaned and the electrodes
(parallel-bar shaped) were placed on their lower limbs
by an experienced physiotherapist on the muscle bel-
lies of semitendinosus (ST), gastrocnemius medialis
(GM), rectus femoris (RF), tibialis anterior (TA) and
gluteus medius (GluMed). The electrodes were placed
in parallel with the process of muscle fibre using dou-
ble-sided tape.
For each subject at first rest values of muscle
activity during quiet standing was measured following
measurements of three jumps Ollie and three jumps
switchstance Ollie. All experiments were recorded by a
video camera located in front of the obstacle.
The indoor track for jumping was 25 meters long
with a cleaned concrete surface. The Ollie jump was
performed over 20 cm high and switchstance Ollie over
2 cm high obstacles. The main purpose of the obstacles
was that all participants perform the jump in the same
place in front of video camera. The instruction was to
jump naturally. The switchstance Ollie obstacle was
lower because this type of jump is more difficult and
all participants were not able to jump over naturally.
Data processing
For processing the raw EMG recording EMG analysis
work program (Delsys, Boston, MA, USA) was used.
The record was rectified and smoothed (using RMS
with window size 25 ms). The processed signal was
exported to MS Excel. Jump phases were selected from
the videos and times of beginning and ending were also
recorded in MS Excel.
These events were defined:
1. the centre of mass at the lowest point;
2. last contact of the front wheel with the ground;
3. last contact of the back wheel with the ground;
4. skateboard at the highest position;
5. first contact of the skateboard with the ground after
flight.
These events define these phases:
1. preparatory phase;
2. take-off phase;
3. flight-up phase;
4. landing phase.
The degree of muscle activity in each phase was
expressed as the integral value (area under the curve)
depending on the time. Resting activity represented
a normative value, to assess activation of selected
muscles during selected jumps. From rest values acti-
vation values (AV) for all monitored muscles were cal-
culated (AV = average + 2 * standard deviation) from
the rest values. Monitored parameters were expressed
as multiples of activation values. For each muscle we
calculated the mean value and standard deviation of 3
monitored attempts.
Independent variables were the type of the jump
and the phase of the jump and the dependent variable
was the muscular activity of target muscles.
Statistical processing was performed by Statistica
(Version 12.0, StatSoft, Tulsa, OK, USA). Normality
of data distribution was tested by Kolmogorov-Smirnov
test. Due to non-normal data distribution differences
in muscle activity between jumping switchstance Ollie
and Ollie were assessed by non-parametric paired Wil-
coxon test. Differences were considered as significant
if the level of statistical significance was p < .05.
For better understanding, results are presented by
the relative difference in muscle activity of Ollie and
switchstance Ollie. Muscle activity in Ollie jumps is
considered as 100%.
Results
Values of total muscle activity during the entire move-
ment are shown in Figure 1 and 2. Differences were
observed independently on front and back limbs
because of different functions of these limbs during
skateboard jumps.
In comparing Ollie and switchstance Ollie we found
significant differences in the activity of RF (p = .022)
and GM (p = .013) on the back lower limb. In both
muscles this activity was significantly higher for switch-
stance Ollie jump.

43
Analysis of muscle activity of Ollie jump in skateboarding
was muscle activity significantly higher (for both mus-
cles p = .028) during the Ollie jump (Figure 1).
Discussion
Jumps in skateboarding require the involvement of mul-
tiple muscle groups and also the optimal timing of their
activity. The number of scientific studies of skateboard-
ing is low and therefore the possibility of comparison
with the results of other measurements is very limited.
In our study we tried to compare the differences in
muscle activity in two basic jumps. Generally it looks
that both jumps are the same, but replacing limbs
Preparatory phase
In the preparatory phase RF (p = .017) and GM
(p = .028) muscle activity is significantly higher for
switchstance Ollie on back lower limb (Figure 2).
Take-off phase and flight-up phase
Although results suggest increased muscle activity dur-
ing switchstance Ollie than during Ollie, we did not
find any significant difference.
Landing phase
Compared muscle activity in switchstance Ollie and
Ollie at this phase we find two significant differences
in TA and ST. In both muscles on the front lower limb
Figure 1. Front lower limb muscle activity during switchstance Ollie in comparison
with Ollie. TA = tibialis anterior, GM = gastrocnemius medialis, RF = rectus femoris,
ST = semitendinosus, GluMed = gluteus medius. *p < .05
Figure 2. Back lower limb muscle activity during switchstance Ollie in comparison
with Ollie. TA = tibialis anterior, GM = gastrocnemius medialis, RF = rectus femoris,
ST = semitendinosus, GluMed = gluteus medius. *p < .05

44 M. Vorlíček et al.
results in different performance. Switchstance Ollie is
more demanding in terms of coordination. This type of
Ollie can replace Ollie performance of the beginners,
because it is rarely trained and movement patterns are
not well automatized. Therefore we can expect differ-
ent muscle activity than in the case of Ollie jump.
Crockett and Jensen (2007) studied involvement of
selected muscles during skateboarding. Their results
showed major involvement of rectus femoris and tibi-
alis anterior. Our study has not the purpose to describe
major involvement muscles, however our results sug-
gest that for optimal jump technique could be useful
to observe also other muscles such as gastrocnemius
medialis and semitendinosus, because in these muscles
we found some difference between easier and more dif-
ficult performance of Ollie.
During the preparatory phase of the jump we found
increased activity of the gastrocnemius medialis and
rectus femoris during switchstance Ollie on the back
lower limb. This difference is also significant in the
muscle activity across the whole jump. Based on this
result, we can conclude that during switchstance Ollie
there is excessive muscle activity on the back lower limb.
The rider has the focus shifted to the back foot instead
of the middle of the skateboard, thus the rider is not
able to effective control muscle force on the back leg.
Due to the lack of training and low level of experiences
with this very complicated complex motion of the rider
is unable to estimate the optimal force acting on the
foot during the take-off phase. The tail of skateboard is
pressed to the ground with an insufficient or excessive
force and the rider cannot dispense adequate muscle
activity for this coordination demanding exercise.
Another significant difference was found in the
increased muscle activity of the tibialis anterior and
semitendinosus at Ollie in front lower limb during the
landing phase of jump. Increased activity of the tibialis
anterior would be explained by better control of brak-
ing by eccentric contraction associated with the plantar
flexion and pronation in the ankle. Increased activity
of semitendinosus would be associated with increased
controlled extension of the knee.
No significant differences were found in muscle
activity of the muscles, which is involved in stabiliz-
ing of the pelvis (gluteus medius). It seems that during
both conditions muscle activity in pelvis is similar.
We also considered limitations of our study. Main
limitation is associated the fact that due to lack of
the time for measurement, we did not perform a test
of maximal voluntary contractions of each muscle.
However some authors presented that mean activation
levels obtained during the task under investigation
would be also considered as normalization procedure
(Halaki & Ginn, 2012).
Conclusions
A comparison of muscle activity of selected muscles
during the various phases of the jump indicates that
during switchstance Ollie skateboarders use higher
muscle activity on the back limb to maintain knee
position. In the front lower limb, results suggest more
active jump performance, better control of movement
and greater range of motion during the Ollie. The study
suggests two training suggestions for the switchstance
Ollie results of. The skater should move his or her cen-
tre of gravity from the tail to the centre of the skate-
board and also he or she would continue with muscle
activity during the landing phase.
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