Yoon, Woo Ram
(Department of Physical Education, Korea National Sport University)
,
Park, Sang Heon
(Department of Physical Education, Korea National Sport University)
,
Jeong, Chan Hyeok
(Department of Physical Education, Korea National Sport University)
,
Park, Ji Ho
(Department of Physical Education, Korea National Sport University)
,
Yoon, Suk-Hoon
(Department of Community Sport, Korea National Sport University)
Objective: The aim of this study was to analyze muscle activation of the lower extremities as a function of changes of the center of pressure (CoP) of the foot during squats in order to provide quantitative information to trainers who would like to teach correct movements for developing muscles. Met...
Objective: The aim of this study was to analyze muscle activation of the lower extremities as a function of changes of the center of pressure (CoP) of the foot during squats in order to provide quantitative information to trainers who would like to teach correct movements for developing muscles. Method: Ten men with over three years of weight training experience participated in this study (age: $26.1{\pm}0.8yrs$, height: $171.2{\pm}3.9cm$, body mass: $71.1{\pm}5.7kg$, 60%RM: $84{\pm}9kg$, career: $4.0{\pm}0.7yrs$). The participants were instructed to perform a squat in each of 3 conditions, with different CoP's (the front, middle, and rear of the foot). Results: The position of the CoP showed significant differences according to instructions in both the eccentric and concentric contraction phases (p < .05). The range of movement of the hip and ankle joints showed significant differences corresponding to changes of the CoP position (p < .05). The rectus femoris and gluteus maximus muscle showed significant differences for different CoP positions only in the concentric contraction phase, while the gastrocnemius and anterior tibialis were significantly different in both the concentric and eccentric contraction phase (p < .05). Conclusion: When the target muscle of squat training is the gastrocnemius, the CoP should be located in the front of the foot for effective muscle training. When the target muscles of squat training are the gluteus maximus and quadriceps femoris, the CoP should be located on the rear of the foot.
Objective: The aim of this study was to analyze muscle activation of the lower extremities as a function of changes of the center of pressure (CoP) of the foot during squats in order to provide quantitative information to trainers who would like to teach correct movements for developing muscles. Method: Ten men with over three years of weight training experience participated in this study (age: $26.1{\pm}0.8yrs$, height: $171.2{\pm}3.9cm$, body mass: $71.1{\pm}5.7kg$, 60%RM: $84{\pm}9kg$, career: $4.0{\pm}0.7yrs$). The participants were instructed to perform a squat in each of 3 conditions, with different CoP's (the front, middle, and rear of the foot). Results: The position of the CoP showed significant differences according to instructions in both the eccentric and concentric contraction phases (p < .05). The range of movement of the hip and ankle joints showed significant differences corresponding to changes of the CoP position (p < .05). The rectus femoris and gluteus maximus muscle showed significant differences for different CoP positions only in the concentric contraction phase, while the gastrocnemius and anterior tibialis were significantly different in both the concentric and eccentric contraction phase (p < .05). Conclusion: When the target muscle of squat training is the gastrocnemius, the CoP should be located in the front of the foot for effective muscle training. When the target muscles of squat training are the gluteus maximus and quadriceps femoris, the CoP should be located on the rear of the foot.
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제안 방법
Accordingly, this study aimed to examine changes in muscle activation in the lower extremities and changes in posture in relation to changes in the CoP (front, middle, and rear) during squatting, and to provide scientific evidence that can be utilized in practice when trainers or individuals performing the squat to perform the exercise in the way that most effectively develops the target muscles.
Before the measurements for the study were taken, participants did the same warm-up exercise they did for the 1RM measurement so that they could perform correct squat movements. To conduct movement analyses, a total of 8 infrared cameras (Oqus 300+, Qualisys, Sweden) were arranged anterior, posterior, and lateral (left and right) to where the participants would perform the squat.
This means that target muscle activation can vary depending on where the CoP is on the sole of the foot. Hence, this study was conducted to investigate the changes in lower extremity muscle activation, CoP, and posture caused by the change in CoP (in the front, middle, and rear of the foot) during squat and to establish scientific evidence based on which an accurate method can be proposed to develop target muscles during training.
The CoP during the squat was measured in each participant to quantitatively test for changes in CoP in the foot in accordance with the 3 instructions (CoP in the front, middle, and rear of the foot). To confirm the change in plantar CoP during the squat, markers were attached in the lower area of the ground reaction force plates, and 2 additional markers were attached to identify the sole of each participant's foot (as shown in (Figure 4)) to normalize the positions of the CoP for varying foot lengths (heel to toe).
This study investigated the effect of the instructions to shift CoP during squat on ROM, muscle activation, and CoP in the lower extre-mities. To do so, ROM, CoP, and muscle activation were analyzed while 10 healthy adult men performed squat as they shifted CoP to the front, middle, and rear of the foot following instruction.
Before the measurements for the study were taken, participants did the same warm-up exercise they did for the 1RM measurement so that they could perform correct squat movements. To conduct movement analyses, a total of 8 infrared cameras (Oqus 300+, Qualisys, Sweden) were arranged anterior, posterior, and lateral (left and right) to where the participants would perform the squat. To measure the ground reaction force of each leg, 2 ground reaction force plates (Type9286AA, Kistler, Switzerland) were placed as shown in (Figure 1).
To confirm whether the CoP shifted in accordance with the instructions to move it, the CoPs were analyzed. The results showed that in both the eccentric contraction and concentric contraction phases, the CoPs were statistically significantly different across the instructions (Table 2, p < .
대상 데이터
For segment modeling of the lower extremities, 24 markers made by the researchers were attached to joint points and segment surfaces of the participants. To measure muscle activation, wireless electromyography (zerowire, Aurion, Italy) was used with the rate of sampling set to 1,000 Hz.
The experiment was conducted in the Sports Biomechanics Laboratory at K University. The one-repetition maximum force (1RM) was measured in all participants a week before experiment to establish the baseline load, using the method recommended by the US National Strength & Conditioning Association (NSCA), in the following manner (Beachle & Earle, 2000).
05). The study participants were students in a weight training club who had continuously trained, and the weight was 60% of the 1RM. Thus, it is likely that they were able to shift CoP comfortably during a squat, even with such a heavy weight.
The study subjects were 10 men in their 20's who had continuously done weight training for at least 3 years and had no physical injury in the most recent 6 months.
The study subjects were 10 men in their 20's who had continuously done weight training for at least 3 years and had no physical injury in the most recent 6 months. They were recruited from a weight training club at K University. The participants' characteristics are shown in (Table 1).
데이터처리
To examine differences in muscle activation, CoP, and ROM in the lower extremities according to the 3 CoP instructions (the front, middle, and rear of the foot) during the squat, one-way repeated measures ANOVA was performed with Bonferroni correction as a post-hoc test. All data analysis was conducted using SPSS 24.
이론/모형
Data were processed using Matlab2014b (Mathworks, USA). Threedimensional spatial coordinates were determined from the imaging data obtained by the 8 infrared cameras, using a non-linear transformation (NLT) method. To model the segments in the lower extremities, a total of 17 reflective markers were attached to landmarks in the right lower limbs of the participants (Figure 3).
성능/효과
The results showed that in both the eccentric contraction and concentric contraction phases, the CoPs were statistically significantly different across the instructions (Table 2, p < .05).
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