Hanseo University, Seosan, 31962, Korea. January 18, 2018

Transcription

1 Volume 118 No , ISSN: (printed version); ISSN: (on-line version) url: ijpam.eu The Changes of the MEF Values of the Agonist During Bench-Press Exercises for the Progressive-Load Form of Type-III Conditions with Different Set Intensities Kyung-Seok 1 and Chun-Ho Yang Dept. of Marine Sports, Hanseo University, Seosan, 31962, Korea January 18, 2018 Abstract The purpose of this study is the investigation of the effect of different types of progressive bench-press loadings on the pectoralis-major, anterior-deltoid, and triceps-brachii muscles. For the study, 10 healthy males from Chungnam who were in their 20s were selected. The selected subjects showed no health problems after undergoing a medical examination, and their weight-training careers consisted of more than 12 months of experience. The experiments were carried out on different Type-III aspects, each of which involved a progressive bench-press loading, and a mixeddesign two-way ANOVA was used. The statistical significance in this study is α =.05. Changes of the pectoralis major MEF: For Type I, the changes tended to increase as the set progressed. For Type II, the changes were increased for the 2 set, and for the 3 set, they tended to decrease. For Type III, the tendency was decreased as the set was progressed. Changes of the anterior-deltoid MEF: For Type 1 503

2 I, a change is not evident for the 1 set compared with the 2 set, but an increase is shown for the 3 set. For Type II, the 1 set showed a decrease compared with the 2 set, and then it was increased for the 3 set. For Type 3, the tendency was decreased as the set was progressed. Changes of the triceps-brachii lateral-head MEF: For Type I, it was decreased for the 2 set compared with the 1 set, and it rose for the 3 set. For Type II, it was decreased for the 1 set compared with the 2 set, and rose for the 3 set. For Type III, the tendency was decreased as the set was progressed. In the low-intensity bench press, the MEF of the pectoralismajor muscle is low, and in the high-intensity bench press, the MEF values of the triceps-brachium and triceps muscles are low. Especially at the 70-% strength, the MEF values of all of the muscles were lowered. Key Words : MEF(Maximum Evocable Force), Bench Press, RM (Repeated Maximum), Muscles 1 INTRODUCTION Resistance exercise leads to an increased physical activity and organization such as muscular hypertrophy and muscular strength due to the adaptation to the muscular nervous system(williams and Wilkins, 2013). The factors that determine the effect of the resistance exercise include the exercise-load intensity, number of repetitions, number of sets, and the interest break time(hass et al, 2001). The setting of the exercise-load intensity affects the training effect, and the mobilized muscle fibers are different(moritani et al, 1986). Resistance exercise causes muscle fatigue. Generally, the higher the resistance intensity, the higher the muscle fatigue(marx et al, 2001). Muscles with a higher percentage of the Type-II fiber tend to exhibit more muscle fatigue(komi and Tesch, 1979). Increased muscle fatigue leads to a decreased muscular function and exercise performance(kraemer et al, 1991). In addition, as the muscular contraction is increased, the electromyography (EMG) level is increased, and when the maximum muscular power is exerted, the increase of the EMG level is according to the number of exercise units 2 504

3 and the frequency of the impulse emissions, and a significant correlation exists between the EMG and the muscular strength(kraemer and Ratamess, 2005). Multijoint movements work in cooperation with two or more agonists(kim, 2014). The bench press is a resistance exercise where the pectoralis-major and triceps muscles act as the agonists(lesuer et al, 1997). When the muscular fatigue of the triceps muscle occurs during the bench-press exercise, the exercise performance is lowered and the development of the pectoralis major is not effective(kim and Yoon, 2015). An EMG measurement contains information on the electrical activity in the body(willardson and Burkett, 2006). The EMG analysis can also obtain muscular information from the anatomical movements, muscle-activity time, and force generation(kao et al, 1995). When myopia is analyzed using EMG, the generalized EMG (iemg) and the mean power frequency (MPF) are used(gerdle et al, 1991). Muscle fatigue is a state in which the requisite strength for muscle contractions is not sufficiently exhibited or maintained, and it is caused by the activity of the nervous system, depolarization, calcium secretion in the myometrium, and the actions of myosin and action(enoka and Stuart, 1992). As the strength is progressed, the muscle-fiber conduction velocity is decreased with the decrease of the muscular strength, and the central frequency shifts from the high-frequency to the low-frequency band; consequently, the mobilization of the Type- II fibers is decreased and the mobilization of the Type-I fibers is increased(braakhekke et al, 1989; Bilodeau et al, 2003). In the previous study, the fatigue material after an 80-% onerepetition maximum (1RM) and a 40-% 1RM showed a high lacticacid level, high heart rate, and increased muscle fatigue at a high intensity(kim, 2006). In addition, the muscle activity and the muscle fatigue differ according to the bench-press load strength(kim, 2013). Although the previously described study of the muscle fatigue was conducted, the measured intensity was limited to a high intensity, and the variable was measured using a program that was all-out exhausted. The purpose of this study is an investigation of the change of the muscle fatigue of the main muscle according to the maximum evocable force (MEF) using the progressive-load 3 505

4 method. 2 METODOLOGY A. Subjects The chosen subjects of the study are 10 male college students who were experiencing no health problems and had engaged in more than one year of resistance exercise. The information of the subjects is shown in <Table 1>, as follows: TABLE 1 B. Research design The bench-press 1RM of each subject was measured using a pretest, and the result served as the basis for the bench presses according to the total of three load strengths that were measured according to the random crossover allocation at 10-day intervals. The rest time is 2 min. To calculate the MEF, the EMG data of the pectoralis-major and triceps-lateral-head muscles were measured during the bench-press exercise. The experimental design is shown in Figure 1, as follows : Figure 1: Experimental design 4 506

5 C. Exercise program The bench-press exercise was undertaken in three forms, and three intensity sets were formulated for each type. The types of motion are Type I - (10 % 1RM) x (20 % 1RM) x (30 % 1RM), Type II - (30 % 1RM) x (40 % 1RM) x (50 % 1RM), and Type III - (30 % 1RM) x (50 % 1RM) x (70 % 1RM). The intensity-setting table for each form is given in <Table 2>, as follows: TABLE 2 D. Variable measurement A surface-emg device(laxtha, Korea) was used to measure the muscular activity of the subjects, and the iemg analysis shows the muscular activity. In this experiment, two surface electrodes were attached at a distance of 1 cm from the insertion points of the endotracheal electrodes. Each time the experiment was performed, the subject was adequately informed and measured. Tape was attached to the attachment area to prevent the influence of noise. The measurements were conducted for the pectoralis-major, anteriordeltoid, and triceps-brachii lateral-head musclesa total of three regions. Markings were made on the electrode-attachment sites for the remeasurement that occurred later. To minimize the skin resistance of the electrode-attachment area, the hair was removed and the skin was polished. The skin was disinfected with alcohol before the electrode was attached. Reference voluntary contraction(rvc) was used as a quantification method for the interindividual and intermuscular comparisons, as well as the comparison during the repeated measurements(hansson et al, 2000). The surface electrode attaching posture of the triceps brachii lateral head is pronation with arm abduction at 90 degrees, and the attachment location was posterior axillary fold distal to the fingers four feet wide. The surface electrode attaching posture of 5 507

6 anterior deltoid is placing your arms on both sides of your torso and pointing your palms towards the sky, and the attachment location was three fingers wide from the front edge of the acromion towards the ground. The surface electrode attaching posture of the pectoral major is supination, and the attachment location is anterior axillary fold. The table of the EMG-patch attachment is shown in <Table 3>, as follows: TABLE 3 3 RESULTS E. Change of the pectorlis-major MEF During the bench-press exercise of the Type-I condition of the pectoralis major, the MEF value tended to increase gradually in every set. During the bench-press exercise of the Type-II condition of the pectoralis major, the MEF value increased between the 1 set and the 2 set, and it then tended to decrease again until the 3 set. During the bench-press exercise of the Type-III condition of the pectoralis major, the MEF value was gradually decreased from the 1 set to the 3 set. The two-way-anova test results of the MEF changes of the pectoralis muscle at the Type-III bench press are shown in <Table 4>, as follows: 6 508

7 TABLE 4 F. Changes of the anterior-deltoid MEF During the bench-press exercise of the Type-1 condition of the anterior deltoid, the MEF value was lowered from the 1 set to the 2 set, and then it tended to increase again until the 3 set. During the bench-press exercise of the Type-II condition of the anterior deltoid, the MEF value was lowered from the 1 set to the 2 set, and thereafter it was increased up to the 3 set, but the difference is not significant. The MEF level was gradually decreased from the 1 set to the 3 set during the bench-press exercise in the Type-III condition of the anterior deltoid. The two-way-anova test results of the MEF changes of the anterior deltoid at the Type-III bench press are shown in <Table 5>, as follows: TABLE 5 G. Changes of the tricepsbrachii lateral-head MEF During the bench-press exercise of the Type-I condition of the triceps-brachii muscle, the MEF value was decreased from the

8 set to the 2 set, and then it tended to increase again until the 3 set. During the bench-press exercise of the Type-II condition of the triceps brachii, the MEF level was lowered from the 1 set to the 2 set, but it was increased until the 3 set, but the difference is not significant. During the bench-press exercise of the Type- III condition of the triceps brachii, the MEF value was gradually decreased from the 1 set to the 3 set. The two-way-anova test results of the MEF changes of the triceps-brachii lateral head at the Type-III bench press are shown in <Table 6>, as follows: TABLE 6 4 DISCUSSION In this study, an attempt was made to understand the main-muscle muscle fatigue according to the exercise-load type based on the MEF response of the agonist when the bench-press exercises of three progressive-load types were performed. The three intensity settings were set to TypeI-10% 1RM 20% 1RM 30% 1RM, type II-30% 1RM 40% 1RM 50% 1RM, type III-30% 1RM 50% 1RM 70%1RM, and the number of repetition times was set to 10. The MEF of the pectoralis major was elevated in all sets as the set progressed, and the MEF of the type II pectoralis major decreased as it progressed from two sets to three sets. At this point, the MEF of type III large chest roots gradually decreased as the set progressed

9 In the Type I condition, the MEF of the anterior deltoid increased from two sets to three sets, and exercise intensity at this point was 30% of 1RM. The MEF of the type II anterior deltoid progressed from one set to two sets and then increased as it progressed to three sets again. Intensity of exercise at the time of lower MEF was 40% of 1RM, it is 50% of 1RM. The MEF of the type III anterior deltoid progressively decreased as the set progressed. MEF of triceps brachii gradually decreased in the Type I condition as the set progressed. The MEF of type II triceps brachii lateral head in two sets from one set and decreased as it progressed to three sets again, and the intensity of exercise at the time of lower MEF was 40% of 1RM, was 50% of 1RM. The MEF of type III triceps brachii lateral head progressively decreased as the set progressed. As intensity of exercise progressively increased, muscle fatigue increased and additional exercise units were mobilized to accumulate muscle fatigue. This increased the iemg value(gerdle et al, 1991). In this study, the type III type bench press gradually increased set strength. In the last set, the MEF decreased due to increased exercise intensity and exercise amount. A bench press corresponds to a multi- joint exercise using two or more muscles(lesure et al, 1997). Because the pectoralis major and triceps brachii complement each other in the bench press exercise, when the muscle activity of the pectoralis major is high, muscle activity of the triceps brachii is low, and activity of the pectoralis major is high when the triceps major activity is high(kim, 2013). In addition, the previous study revealed that high-intensity maximum repetitive bench presses produced high muscle activity in triceps brachii and high-intensity repetitive bench presses revealed high muscle activity in pectoralis major(kim, 2007). In this study, the width of the MEF from one set to three sets in the type III pectoralis major was ± ± 4.42, The change range of MEF was ± ± and ± ± 13.07, respectively. This study suggests that the type III and type II exercise muscles have higher muscle strength than those of type I and type II exercise types. This suggests that the type III type of exercise in this study had a higher intensity than the type I and type II exercise types, suggesting a low degree of MEF in the triceps brachii. In the last set of type III both 9 511

10 pectoralis major, anterior dektoid, and triceps brachii developed low MEF. The maximum repetitive motion occurred because the mobilized units were fatigued and the nerve-conduction velocity was slow. As a result, the average EMG frequency shifted from the high frequency to the low-frequency bandwidth, resulting in a low MEF value(basmajian and De Luca, 1985). In this study, 70% of 1RM, the strength of three sets of Type III, was achieved near the maximum repetition because the weight was set on 1RM basis(fleck and Kraemer, 2014). In this study, the intensity of each set was set on the basis of 1RM for each condition, and the repetition frequency was repeated 10 times. Only three sets of type III were used for maximum repetition of all types. Therefore, as the number of sets in the conditions 1 and 2 increased, the fatigue improved as the set progressed. The MEF value of the three sets with 30% 1RM intensity in the pectoralis muscle type I was ± 9.58 (Hz), and the MEF value was ± 4.90 (Hz) in one set of exercise with 30% 1RM intensity in type II. The same intensity of exercise was used, but Type I was subjected to 30% 1RM bench presses in three sets after two sets, and 30% 1RM bench press in the first set was conducted immediately in type II. The MEF was ± 4.35 (Hz) in three sets of 50% 1RM intensity in type II. In two sets with 50% 1RM intensity in Type III, the MEF value was ± 4.69 (Hz). This is also thought to be the same phenomenon. 5 CONCLUSION In this study, the difference between the muscle-fatigue changes in the pectoralis-major, triceps, and triceps-brachii muscles during the performances of bench-press exercises under different Type-III conditions are shown according to the MEF. First, during the bench-press exercise of the Type-I condition of the pectoralis major, the MEF value tended to increase gradually in every set. During the bench-press exercise of the Type-II condition of the pectoralis major, the MEF value was increased from the 1 set to the 2 set, and then it tended to decrease again until the

11 set. During the bench-press exercise of the Type-III condition of the pectoralis major, the MEF value was gradually decreased from the 1 set to the 3 set. Second, during the bench-press exercise of the Type-I condition of the anterior deltoid, the MEF value was lowered from the 1 set to the 2 set, and then it tended to increase again until the 3 set. During the bench-press exercise of the Type-II condition of the anterior deltoid, the MEF value was lowered from the 1 set to the 2 set, and thereafter it was increased up to the 3 set, but the difference is not significant. The MEF level was gradually decreased from the 1 set to the 3 set during the bench-press exercise under the Type-III condition of the anterior deltoid. Thirdly, during the bench-press exercise of the Type-I condition of the triceps-brachii muscle, the MEF value was decreased from the 1 set to the 2 set, and then it tended to increase again until the 3 set. During the bench-press exercise of the Type-II condition of the triceps brachii, the MEF level was lowered from the 1 set to the 2 set, but it was increased until the 3 set, but the difference is not significant. During the bench-press exercise of the Type- III condition of the triceps brachii, the MEF value was gradually decreased from the 1 set to the 3 set. As a result, when the bench-press motions of the three conditions with the different set intensities were performed, the change of the MEF value did not decrease unless it proceeded to a low intensity or an all-out performance. When all-out progress was made, it was gradually decreased. These results suggest that a low intensity or a bench press that is not an all-out performance and the performance of a warm-up exercise reduce the muscle fatigue and increase the MEF value. References [1] American College of Sports Medicine, 2013, ACSM s guidelines for exercise testing and prescription. Lippincott Williams &Wilkins. [2] Basmajian, J. V. & De Luca, C. J, 1985, Muscles alive: their functions revealed by electromyography. Williams & Wilkins

12 [3] Bilodeau, M., Schindler-Ivens, S., Williams, D. M., Chandran, R., & Sharma, S. S, 2003, EMG frequency content changes with increasing force and during fatigue in the quadriceps femoris muscle of men and women, Journal of Electromyography and Kinesiology, 13(1), [4] Braakhekke, J. P., Stegeman, D. F., & Joosten, E. M. G, 1989, Increase in median power frequency of the myoelectric signal in pathological fatigue, Electroencephalography and clinical neurophysiology, 73(2), [5] Enoka, R. M., & Stuart, D. G, 1992, Neurobiology of muscle fatigue. Journal of applied physiology, 72(5), [6] Fleck, S. J., & Kraemer, W, 2014, Designing Resistance Training Programs, 4E. Human Kinetics. [7] Gerdle, B., HENRIKSSONLARSN, K., Lorentzon, R.& WRETLING, M. L, 1991, Dependence of the mean power frequency of the electromyogram on muscle force and fibre type, Acta Physiologica, 142(4), [8] Gerdle, B., HENRIKSSONLARSN, K., Lorentzon, R., & WRETLING, M. L,1991, Dependence of the mean power frequency of the electromyogram on muscle force and fibre type. Acta Physiologica, 142(4), [9] Hansson, G.., Balogh, I., Ohlsson, K., Plsson, B., Rylander, L., & Skerfving, S, 2000, Impact of physical exposure on neck and upper limb disorders in female workers, Applied ergonomics. 31(3), [10] Hass, C. J., Feigenbaum, M. S., & Franklin, B. A, 2001, Prescription of resistance training for healthy populations. Sports medicine, 31(14), [11] Kao, J. T., Pink, M., Jobe, F. W., & Perry, J, 1995, Electromyographic analysis of the scapular muscles during a golf swing, The American journal of sports medicine, 23(1), [12] Kim Ki-Hong & Yoon Chul, 2015, Effects of Methods for Warm-Up prior to Bench Press Exercise on Electromyogram,

13 Muscle Fatigue and the Number of Repetitions in Pectoralis and Triceps, 24(2), [13] Kim Ki-Hong, 2013, The Effect of Bench Press Combined Joint Movement on Muscle Activity and Number of Repeats, KACEP Workshop, 38, 64. [14] Kim Ki-Hong, 2013, The Effect of Bench Press Combined Joint Movement on Muscle Activity and Number of Repeats. KACEP Workshop, 38, 64. [15] Kim Ki Hong, 2007, The Effect of Adaptation of Exercise Intensity on Agonist Muscle Activation, Fatigue, and Strength on the Supine Bench Press(Doctoral dissertation). Sejong University. [16] Kim, Jeong-Hwan, 2006, The change in blood lactic acid level,heart rate, andelectromyogram in the intervals between- Weight training exercise load strength. Unpublished master s thesis, Keimyung University. [17] Kim, Ki-Hong, 2014, Effects of Method and Intensity of Resistance Exercise on Pectoralis Major and Triceps Brachii iemg, MEF, Repetition at 10RM Bench Press after Single Joint All out Pre Exercise. Health & Sports Medicne, 16(2), [18] Komi, P. V., & Tesch, P, 1979, EMG frequency spectrum, muscle structure, and fatigue during dynamic contractions in man. European journal of applied physiology and occupational physiology, 42(1), [19] Kraemer, W. J., & Ratamess, N. A, 2005, Hormonal responses and adaptations to resistance exercise and training. Sports medicine, 35(4), [20] Kraemer, W. J., Gordon, S. E., Fleck, S. J., Marchitelli, L. J., Mello, Ros, J. E., & Fry, A. C, 1991, Endogenous anabolic hormonal and growth factor responses to heavy resistance exercise in males and females. International journal of sports medicine, 12(02),

14 [21] LeSuer, D. A., McCormick, J. H., Mayhew, J. L., Wasserstein, R. L., & Arnold, M. D, 1997, The accuracy of prediction equations for estimating 1-RM performance in the bench press, squat, and deadlift. Journal of strength and conditioning research, 11, [22] LeSuer, D. A., McCormick, J. H., Mayhew, J. L., Wasserstein, R. L., & Arnold, M. D, 1997, The accuracy of prediction equations for estimating 1-RM performance in the bench press, squat, and deadlift. Journal of strength and conditioning research, 11, [23] Marx, J. O., Ratamess, N. A., Nindl, B. C., Gotshalk, L., Volek, J. S., & Dohi, K. The effects of single-set vs. periodized multiple-set resistance training on muscular performance and hormonal concentrations in women. Med. Sci. Sports Exerc, , [24] Moritani, T. O. S. H. I. O., Muro, M. A. S. U. O., & Nagata, A. K. I. R. A, 1986, Intramuscular and surface electromyogram changes during muscle fatigue, Journal of Applied Physiology, 60(4), [25] Willardson, J. M., & Burkett, L. N, 2006, The effect of rest interval length on bench press performance with heavy vs. light loads, Journal of Strength and Conditioning Research, 20(2),

15 517

16 518