53 1 1 2 3 4 Characteristics of load and EMG during different knee angled bilateral and unilateral leg press exercises in jumpers Takahisa Yoshida 1 Chikara Miyaji 1 Keigo Byun Ohyama 2 Takanori Sugibayashi 3 and Yukito Muraki 4 Abstract The purpose of this study was to examine the load characteristics during different knee angled leg press exercises at bilateral and unilateral conditions. The subjects were fourteen male jumpers in athletics, aged 22yrs. They performed isometric leg press exercise, knee angled 9 and 12 in bilateral and unilateral conditions. Analyzed outputs were the maximum peak forces and the explosive strengths. The sum of the outputs in unilateral conditions (UL) was compared with the output at bilateral condition (BL) at each of knee angles. Due to the comparison of the muscular activities, the selected six athletes of EMG activities were measured during the tests. With regard to the maximum forces, UL were greater than BL and the maximum forces at 12 knee angle were larger than these at 9 knee angle. BL/UL ratios of the peak force at 9 and 12 knee angles were 91 and 92 respectively (N.S.). UL of the explosive strength at 12 knee angle was greater than the same strength of BL and UL at 9 of the knee angle significantly. As for the EMG activities, the major muscular activities had changed from knee extensor muscles to hip extensor muscles with increase in the knee angles from 9 to 12. The muscular activities of unilateral conditions were tending to be larger than bilateral condition at each knee angles. Key words: leg press exercises, bilateral and unilateral condition, knee angle, jumpers 1999, 1984 23 9 12 1 Japan Institute of Sports Sciences 2 Comprehensive Human Sciences, University of Tsukuba 3 Faculty of human science, Kanazawa Seiryo University 4 Faculty of Sport & Health Studies, Hosei University
54 25 1 53 65 23 11 27 27 pp.88-89 28 12 23 Secher 1988 9 1 15 18 28 Henry and Smith, 1961 Secher, 1975 1997 BL Bilateral UL Unilateral 9 12 BL/UL BL / UL 1 1421.5 3.1.77.6m 66.4 5.1kg 3198 4 Table 1
55 Table 1 Characteristics of the subjects mean SD Event n Personal Best m Height m Weight kg Age yrs High Jump 3 2.1.6 1.8.5 7.7 3.2 2.7 2.5 Long Jump 3 7.44.44 1.76.3 64.7 2.9 2.7 1.5 Triple Jump 7 15.57.78 1.77.8 64.3 5. 22.1 4. Pole Vault 1 5. 1.77 74. 22. Figure 1 9 12 2 9 12 9, 12deg Load cell Figure 1 Set up of the experimental apparatus and the knee joint angle 2 1 6 1 6 EMG Gmax Gmed BF VM RF ES-TL ES-LL 2 6 maximum voluntary contraction MVC 9 9
56 25 1 53 65 23 11 Figure 1 A/D 1kHz 1Hz EMG 2cm A/D 1ms Apple 1Hz integrated EMG iemg 495N Fmax explosive strength Fexp f / t Schmidtbleicher, 1992 BL UL EMG 5ms 1msiEMG mean EMG memg memg MVC MVC 2 2 2 1 Turkey- Kramer BL /UL t 5 Figure 2 Fmax BL UL 9 BL 2174. 355.N UL 2382.5 321.5N 12 BL 3735. 636.9N UL 476. 44.6N 2 12 9 UL BL Figure 3 / BL/ UL BL UL BL/ UL 991.4 1.9 12 91.8 15. BL 1 Figure 4 Fexp BL UL 9 BL 8.8 4.5N/ms UL 9.3 5.2N/ms 12 BL 11.7 6.2N/ms, UL 17.2 9.5N/ms 2 2 Turkey-Kramer 12 UL 9 BL UL
57 (N) p <.5 5 4 3 2 1 BL UL BL UL 9deg 12deg Figure 2 Comparisons of the mean and the standard deviation of the maximum force (Fmax) at the 9 and 12 degrees of the knee angles between bilateral and unilateral conditions in the isometric leg press. BL: the output value of bilateral condition UL: sum of the output value of unilateral conditions (%) 14 12 1 8 6 4 2 9deg 12deg Figure 3 Comparison of the mean and the standard deviation of the BL/ UL ratio of the maximum force (Fmax) between at 9 and 12 degree knee angles during the isometric leg press. (N/ms) p<.5 35 3 25 2 15 1 5 BL UL BL UL 9deg 12deg Figure 4 Comparisons of the mean and the standard deviation of the explosive strength (Fexp) at 9 and 12 degrees of knee angles between bilateral and unilateral conditions during the isometric leg press. BL: the output value of bilateral condition UL: sum of the output value of unilateral conditions
58 25 1 53 65 23 11 Figure 5 BL/ UL BL / UL 9 14.1 38.3 12 74.3 29.9 BL /UL 2 9 BL /UL 12 Table 2 9 BL UL r.75 9 BL UL r.82 9 BL 12 BL r.75 9 BL 12 UL r.56 9 UL 12 BL r.87 9 UL 12 UL r.64 12 BL 12 UL r.63 9 UL 9 UL r.59 9 UL 12 BL r.6 (%) 14 p<.5 12 1 8 6 4 2 9deg 12deg Figure 5 Comparison of the mean and the standard deviation of the BL/ UL ratio of the explosive strength (Fexp) between at 9 and 12 degree knee angles during the isometric leg press. Table 2 Correlation of the output values between the maximum force (Fmax) and the explosive strength (Fexp) at 9 and 12 degrees of the knee angles during bilateral and unilateral leg press exercises. p<.5 Fmax_BL_9 Fmax_UL_9 Fmax_BL_12 Fmax_UL_12 Fexp_BL_9 Fexp_UL_9 Fexp_BL_12 Fexp_UL_12 Fmax_BL_9 1.75.41.37.12.25.33.3 Fmax_UL_9 1.9.46.45.59.6.42 Fmax_BL_12 1.38.8.1.18.21 Fmax_UL_12 1.35.22.44.39 Fexp_BL_9 1.82.75.56 Fexp_UL_9 1.87.64 Fexp_BL_12 1.63 Fexp_UL_12 1 The key is as follows; Fmax: maximum force, Fexp: explosive strength, BL: the output value of bilateral condition, UL: sum of the output value of unilateral conditions.
59 Table 3 MVC Figure 6 9 MVC 9MVC 9MVC Figure 7 12 MVC 12MVC MVC Figure 8 MVC 9 MVC 12 12 MVC 9 Figure 9 MVC 9 MVC 12 12 MVC 9 2 UL BL 12 9 Figure 2 1997 9 165 5 9 12 12 9 Table 3 MVC activities of bilateral (upper) and unilateral conditions (lower) during the isometric leg press at 9 and 12 degrees of the knee angle. Bilateral Condition ES-TL ES-LL Gmed Gmax BF VM RF 9deg 67.3 33.5 52.7 2. 11.3 6.5 51.6 21.4 12.3 9.2 68. 11.8 69. 27.1 12deg 11.9 12.3 1.2 9.9 2.5 14.8 74.1 14. 25.3 16.2 66.4 19.8 49.2 35. Unilateral Condition ES-TL ES-LL Gmed Gmax BF VM RF 9deg 23.3 1.9 32.1 13. 13.6 14.6 65.4 21.4 1.8 7. 78.7 24. 83. 42. 12deg 8.4 6.2 1. 7.2 39.1 12.9 79.6 26.9 29.4 2.9 63. 14.1 46.3 32.6 p<.5 The key is as follows, ES-TL: m.erector spinae of take off leg, ES-LL: m.erector spinae of lead leg, Gmed: m.glutceus medius, Gmax: m.gluteus maximus, BF: m.biceps femoris longum, VM: m.vastus medialis, RF: m.rectus femoris.
6 25 1 53 65 23 11 (%) 14 Bilateral condition Unilateral condition p<.5 12 1 8 6 4 2 ES-TL ES-LL g-med g-max bf vm rf Figure 6 Comparison of MVC activities of bilateral and unilateral leg press at 9 degrees of the knee angles. The key is as follows, ES-TL: m.erector spinae of take off leg, ES-LL: m.erector spinae of lead leg, Gmed: m.glutceus medius, Gmax: m.gluteus maximus, BF: m.biceps femoris longum, VM: m.vastus medialis, RF: m.rectus femoris. (%) 14 Bilateral condition Unilateral condition p<.5 12 1 8 6 4 2 ES-TL ES-LL g-med g-max bf vm rf Figure 7 Comparison of MVC activities of bilateral and unilateral leg press at 12 degrees of the knee angles. The key is as follows, ES-TL: m.erector spinae of take off leg, ES-LL: m.erector spinae of lead leg, Gmed: m.glutceus medius, Gmax: m.gluteus maximus, BF: m.biceps femoris longum, VM: m.vastus medialis, RF: m.rectus femoris. BL 1561N UL 1694N 26 3 6 12 12 9 BL UL 9 2N 12 35N
61 (%) 14 9deg 12deg p<.5 12 1 8 6 4 2 ES-TL ES-LL g-med g-max bf vm rf Figure 8 Comparison of MVC activities at 9 and 12 degrees of the knee angles during bilateral leg press. The key is as follows, ES-TL: m.erector spinae of take off leg, ES-LL: m.erector spinae of lead leg, Gmed: m.glutceus medius, Gmax: m.gluteus maximus, BF: m.biceps femoris longum, VM: m.vastus medialis, RF: m.rectus femoris. (%) 14 12 9deg 12deg p<.5 1 8 6 4 2 ES-TL ES-LL g-med g-max bf vm rf Figure 9 Comparison of MVC activities at 9 and 12 degrees of the knee angles during unilateral leg press. The key is as follows, ES-TL: m.erector spinae of take off leg, ES-LL: m.erector spinae of lead leg, Gmed: m.glutceus medius, Gmax: m.gluteus maximus, BF: m.biceps femoris longum, VM: m.vastus medialis, RF: m.rectus femoris. UL BL BL UL BL/UL 991.4 1.9 12 91.8 15. BL1 9 BL/UL Schantz et al 1989 92 88 87 88 86 Secher et al. 1988 15 BL /UL 81 86 Henry and Smith, 19611997 1 2
62 25 1 53 65 23 11 9 12 91.4 91.8BL 1 1997 23 12 28 2 BL /UL 9 97.8 12 72.6 2 9BL 2.2 12 27.4 BL /UL 2 BL 27 pp.88-89 BL BL /UL 991.4 12 91.8 BL, 28 9BL UL r.75 12 BL UL r.38 28 BL UL 9 BL UL 12 BL UL 12 UL 9 BL UL Figure 4 FT Vandervoort et al, 1984, 1987; Koh et al, 1993; Oda and Moritani, 1994 FT BL UL BL UL 12 UL 9 BL UL
63 12 1994 Secher 1975 1993 1998.2 Hay, 1973 125 17 1994 12 9 Figure 6, 7 28 9 12 26 3 6 9 12 12 9 12 1979 1996 12 12 129 12 9 9 Figure 8, 9
64 25 1 53 65 23 11 26 27 pp36. 9 129 9 12 9 12 14 9 12 EMG 12 9 UL BL 9 12 BL /UL 91.4 91.8 9 BL UL r.75 12 r.38 12 UL 9 BL UL 9 12 9 12 198 5 198. 1996pp. 82 111. 26 pp.13 118. Hay, J. G. (1973) The Hay Technique Ultimate in High Jump Style? Athletic Journal, 53 7 113 115. Henry, F.M. and Smith, L.E. (1961) Simultaneous vs. separate bilateral muscular contractions in relation to neural overflow theory and neuromoter specificity. Res. Quart. 32 42 46. 1997 Closed Kinetic Chain Open Kinetic Chain 24 6 341 346. 1999 HD pp.177 182. Koh, T.J., Grabiner, M.D., and Clough, C.A. (1993) Bilateral deficit is larger for step than for ramp isometric contractions. Journal of Applied Physiology, 74, 12 125.
65 26. pp.81 12. 1984 UP. 18 4 15 157. 1994 HD pp.15 16. 1997 1 2 122 131 1998 pp.166 169. Oda, S. and Moritani, T. (1994) Maximal isometric force and neural activity during bilateral and unilateral elbow flexion in humans. Eur. J. Appl. Physiol, 69 24 243. Schantz, P.G., Moritani, T., Karlson, E., and Johansson, E. (1989) Maximal voluntary force of bilateral and unilateral leg extension. Acta Physiol Scand, 136 185 192. Secher, N.H. (1975) Isometric rowing strength of experience and inexperience oarsman. Medicine and Science in Sports, 7 28 283. Secher, N. H., Rube, N. and Elers, J. (1988) Strength of two- and one-leg extension in man. Acta. Physiol. Scand., 134 333 339. Schmidtbleicher, D. (1992) Training for power events. In: P. V. Komi (Ed.) Strength and power in sport. Blackwell Scientific: London, pp.381 395. 1993 9 33 38. Vandervoort, A.A., Sale, D.G., and Moroz, J. (1984) Comparison of motor unit activation during unilateral and bilateral leg extension. J. Appl. Physiol., 56 1 46 51 1979 pp. 176. 27 23 16 1 75 82 28, 22 1 29 39.