An investigation into the force-EMG relationship for static and dynamic exertions
- Authors: Koekemoer, Wesley Agosthinho
- Date: 2022-04-06
- Subjects: Electromyography , Force and energy , Muscles Physiology , Biomechanics , Muscle contraction , Isometric exercise , Isotonic exercise , Static and dynamic exertions
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/291076 , vital:56816
- Description: The force-EMG relationship has multiple applications in varying fields of study and practice. One such application is the development of safety guidelines and regulations. Current guidelines are based on static muscle actions even though the majority of tasks encountered in industry are dynamic in nature. This may have negative implications for the health, safety, and productivity of workers as regulations based on static muscle actions may place higher force demands on manual labourers compared to what would be expected if regulations were based on dynamic muscle actions. Regulations based on dynamic muscle actions may be more effective in worker safety as the nature of the regulation matches that of the demand. Few studies have investigated the force-EMG relationship during dynamic muscle actions and the few that do exist have reported contradictory / mixed results. Therefore, the purpose of this study was to: 1) gain an understanding of EMG responses at different load levels, and 2) show how the relationship differs between static and dynamic muscle actions. A two-factorial repeated-measures experiment was developed for this study. Eighteen experimental conditions, utilizing six load levels (0%, 20%, 40%, 60%, 80%, and 100% of maximum voluntary force) for each of the three muscle actions (isometric, concentric and eccentric). Surface EMG responses were obtained under these conditions by repeatedly dorsiflexing and plantarflexing the foot, thus activating the soleus muscle. A maximum voluntary exertion on an isokinetic dynamometer determined the maximum force level, based on which the sub-maximal loads were calculated and added to a pulley system. 31 student participants were recruited for this experiment which was conducted over two sessions – one information and habituation session, and one experimental session. The EMG data recorded were processed and checked for normality and outliers. The data was then analysed via a General Linear Model analysis to determine the effect of exertion type and of load level on the muscle activity. Significant differences were identified at p<0.05 and followed by a Tukey post-hoc test. Correlation analyses were also conducted to determine the relationship between the force and EMG at all three exertion types. All dependent measures showed that as the load level increased so did the sEMG amplitude for all muscle actions. Muscle actions differed significantly between majority of six force levels. Correlations between the load levels and sEMG amplitude for each muscle action indicated a significant correlation with a moderate strength. The conclusion draws from this study that there is a positive correlation between force and sEMG amplitude, at all load levels, with a moderate strength. However, the muscle actions differed significantly from each other. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2022
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- Date Issued: 2022-04-06
Effects of elastic-band tension training on strength, speed, agility and vertical jump height in university soccer players
- Authors: Katushabe, Edgar
- Date: 2018
- Subjects: Basics of elastic resistance training , Elastic resistance training for stability, strength, and power , Isometric exercise , Soccer -- Training
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/30638 , vital:31001
- Description: Soccer is regarded as one of the most popular sports in the world, and involves explosive physical actions such as kicking, jumping, rapid changes of direction and sprinting. These attributes would suggest that strength, power, and agility may play an important role in soccer performance. Elastic band resistance training serves to increase strength, power, speed, balance, coordination and agility However, there is little published research available on the use and effectiveness of elastic-band resistance training as a tool for improvement in muscular strength and power of soccer players. Purpose: To determine the effect of elastic-band resistance training on strength, speed, agility and vertical jump height of university soccer players. The present study used a pre-test post-test experimental study design. The participants comprised of 15 Eastern Cape male soccer players, currently affiliated with the Nelson Mandela University soccer teams. Participants were randomly allocated into one of two groups: a conventional resistance training group, and an elastic band tension resistance training group. Stratified random sampling was used to ensure an even distribution of the performance levels and training experience between the participants. Analysis implemented used Microsoft Excel® and the latest version of Statistica for the purpose of descriptive and inferential statistics. Additionally, Pearson correlation coefficient and coefficient of determination were used to identify statistical correlations between variables of interest. Inferential statistics were applied using analysis of covariance (ANCOVA), and in the case of significant findings, the Scheffé post-hoc test was utilized for comparisons. Independent t-tests indicated significant between-group differences. The alpha level was set at 0.05. Results: The main findings were that elastic band resistance training would appear to be a superior method to conventional resistance training given that: This method was able to produce greater results in improving maximal vertical jump when compared to free weight resistance training (ANCOVA, F(1,25)=9.1135, p=0.00577), produced faster 40m iv sprint times in comparison to free weight resistance training (ANCOVA, F(1, 25)=4.534, p=0.043), and produced significant improvements in one repetition maximum performance in the squat (ANCOVA, F(1, 25)=5.454, p=0.028). Based on the results of this study, it would appear that both the elastic band resistance training and free weight resistance training were effective in increasing performance in both the one repetition maximum deadlift and agility tests, with no significant difference between the two methods (ANCOVA, F(1, 25) =0.328, p=0.572), ANCOVA, F(1, 25)=3.597, p=0.069 respectively). Elastic band resistance training may be an effective alternative training methodology to improve performance variables in university soccer players. However, further research may be needed to clearly define the role of combined elastic band resistance training in the periodization of soccer training in a competitive season.
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- Date Issued: 2018