Sports Science


Although the noninvasive nature of surface EMG makes this technique ideal for clinical use and research, EMG data can be variable, which raises questions about the reliability of this technique [44]. Repeatability of EMG data is established for many isometric exercises but less is known about the reliability of this method of analysis during dynamic exercise, particularly ballistic movements [45,46,44]. Most studies assessing EMG reliability of data in dynamic movements have examined slow, controlled tasks, such as resistance training exercises or gait. Therefore, evaluation of the reliability of EMG during ballistic tasks is essential to determine the viability of this methodology for clinical and research applications [47,48-49-50,44]. Surface EMG, sometimes called kinesiological electromyography, is the electromyographic analysis that makes it possible to obtain an electrical signal from a muscle in a moving body [41]. It has to be added, by way of clarification, that according to this definition its use is limited to those actions that involve a dynamic movement. Nevertheless, it is also applicable to the study of static actions that require a muscular effort of a postural type [41].

diseases and in voluntary occupational or sports movements [52,21,17]. The measurement of kinesiological EMG in sport and specific field circumstances, such as the track and/or soccer field, the alpine ski slope, the swimming pool and the ice rink, demands a specific technological and methodological approach, adaptable to both the field and the sport circumstances [52]. Sport movement techniques and skills, training approaches and methods, ergonomic verifi‐ cation of the human-machine interaction have, amongst others, a highly specialized muscular activity in common. The knowledge of such muscular action in all its aspects, its evaluation and its feedback should allow for the optimization of movement, of sports materials, of training possibilities and, in the end, of sports performance [52]. Drawing conclusions from a review of the EMG research of 32 sports, covering over 100 different complex skills, including methodological approaches, is an impossible task. EMG and sports is a vast area and a complete review is impossible, as information will be found scattered in many different journals, including those on the sports sciences, ergonomics, biomechanics, applied physiol‐

Surface Electromyography in Sports and Exercise

http://dx.doi.org/10.5772/56167

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sEMG refers to surface electromyography and measures muscle activity in microvolts. This form of feedback allows us to determine if muscles not involved in a particular skill need to be relaxed and those muscles involved in a skill need to fire in the right sequence and with the right amplitude. In addition to using sEMG feedback for training purposes, the information can also provide insight into the athlete's strength and conditioning or the effects of an injury

EMG can also be used to examine the activation characteristics of specific muscle groups.

Amplitude and power spectrum of sEMG are commonly used to quantify neuromuscular

Because of the characteristics of electrodes used, sEMG enables us to study different muscles at the same time, without any inconvenience to the individual, with the advantage that the majority of sEMG equipment can accommodate different inputs simultaneously [55,41]. It also allows greater reproducibility of the traces obtained in different recordings. In addition, the recording obtained is more representative of the muscle as a whole rather than of a particular area. Nevertheless, as already discussed, obtaining traces that provide less information regarding the characteristics of the MUAPs is a limitation in those cases where this particular

Another limitation is the fact that in some dynamic actions there can be displacement and modification of the volume of the muscle being analyzed. A change in the relative position of the muscle in relation to the electrode means that the same spatial relationship is not main‐ tained between them, which affect the intensity of the signal that is recorded. Because of this, the best conditions for carrying out an sEMG, depending on the use and application required,

The majority of activities in sport and occupational settings involve complex movement pat‐ terns often complicated by external forces, impacts and the equipment used during the move‐

are those that are similar to those needed for an isometric type of study [5,56,57,11].

ogy, in different congress proceedings, and so on [52].

rehabilitation program [53].

activity and fatigue [54].

*3.1.1. The limitations of sEMG*

type of examination is of specific interest [41].

The visual systems employed for motion analysis of cycling, even though scientific and accurate, can only indicate the apparent movements. It is often necessary to know how the movements are actually performed against a resistive load. For this reason electro‐ myographic techniques are employed in conjunction with biomechanical analyses [51]. EMG is generally used to indicate which muscle groups are active during a given seg‐ ment of the pedal revolution.

Surface electrodes are usually attached to the muscle groups to be studied. The action poten‐ tials generated are recorded during the pedaling action, thereby allowing the researcher to gain a more complete insight into the muscles employed and the extent of their involvement while pedaling [22]. Within EMG, a particular specialty has been developed wherein the aim is to use EMG for the study of muscular function and co-ordination. This area of research is usually called kinesiological EMG [52,47]. The general aims of kinesiological EMG are to analyze the function and co-ordination of muscles in different movements and postures, in healthy subjects as well as in the disabled, in skilled actions as well as during training, in humans as well as in animals, under laboratory conditions as well as during daily or vacational activities [52]. This is usually used by a combination of EMG, kinesiological and biomechanical measurement techniques [52,47]. Because there are over 600 skeletal muscles in the human body and both irregular and complex involvement of the muscles may occur in neuromuscular diseases and in voluntary occupational or sports movements [52,21,17]. The measurement of kinesiological EMG in sport and specific field circumstances, such as the track and/or soccer field, the alpine ski slope, the swimming pool and the ice rink, demands a specific technological and methodological approach, adaptable to both the field and the sport circumstances [52]. Sport movement techniques and skills, training approaches and methods, ergonomic verifi‐ cation of the human-machine interaction have, amongst others, a highly specialized muscular activity in common. The knowledge of such muscular action in all its aspects, its evaluation and its feedback should allow for the optimization of movement, of sports materials, of training possibilities and, in the end, of sports performance [52]. Drawing conclusions from a review of the EMG research of 32 sports, covering over 100 different complex skills, including methodological approaches, is an impossible task. EMG and sports is a vast area and a complete review is impossible, as information will be found scattered in many different journals, including those on the sports sciences, ergonomics, biomechanics, applied physiol‐ ogy, in different congress proceedings, and so on [52].

sEMG refers to surface electromyography and measures muscle activity in microvolts. This form of feedback allows us to determine if muscles not involved in a particular skill need to be relaxed and those muscles involved in a skill need to fire in the right sequence and with the right amplitude. In addition to using sEMG feedback for training purposes, the information can also provide insight into the athlete's strength and conditioning or the effects of an injury rehabilitation program [53].

EMG can also be used to examine the activation characteristics of specific muscle groups.

Amplitude and power spectrum of sEMG are commonly used to quantify neuromuscular activity and fatigue [54].
