近年來由於生活品質提高，使得休閒運動的風潮盛行，因此肌肉的強化訓練是一個很常見的現象，而伏地挺身運動更是常用於鍛鍊上肢肌肉。透過運動學與動力學模擬的上肢關節間受力情形是一種常見的方式。因此本實驗首先邀請14位無上肢傷殘病史的年輕男性參與實驗計畫，利用非侵入式的3D動態量測系統(包括8部擷取頻率240fps攝影機量測固定於身體解剖標記點之反光球的空間位置，並結合頻率1000Hz的Kistler測力板量得地面反作用力與反作用力矩)來模擬上肢各關節在不同伏地挺身速度下(快速組頻率：每10秒7下；中速組：每10秒5下；慢速組：每10秒4下)所承受的負載情形，分析伏地挺身速度對於伏地挺身過程中對上肢肌肉骨骼系統的影響，計算出上肢關節在伏地挺身過程中各關節的受力與受力矩，希望找出減少上肢關節的剪應力負荷的方式藉此提供各關節在動態負載下預防受傷的機制。實驗結果發現，在關節受力方面，快速組的肘關節的最大內側剪應力與最大軸向力分別高於慢速組1.35與1.23倍；且快速組的肩關節的最大前向剪應力與最大軸向力也分別高於慢速組1.24與1.28倍。而關節受力矩方面肘關節的最大外翻力矩以、伸展力矩及旋前力矩與肩關節的最大屈曲力矩及內收力矩在快速組時也都分別高於慢速組1.63、1.34、1.41、1.36與1.37倍。因此這些由速度增加提高關節的受力與受力矩可能會增加上肢關節的負荷。
其次進一步利用上肢肌肉的表面肌電訊號，以及疲勞前後的最大肌肉耐力測試，希望了解不同伏地挺身的速度對於上肢肌肉的訓練成效。針對15位健康且慣用手為右手的年輕男性，以肌肉訊號分析系統量測其旋前、旋後肌、胸大肌、前中後三角肌、三頭肌、肱二頭肌、脊上肌、小圓肌在整個訓練過程中肌肉的總活化量以及使用等速肌力儀量測疲勞上肢在運動前與完全疲勞後的肌力衰退量。實驗結果發現，慢速組對三頭肌、肱二頭肌、前後側三角肌及主胸大肌的總肌肉活化量高於快速組1.47、2.43、1.42、1.91與1.48倍，顯示放慢速度時的訓練下對肌肉有加強訓練的效果。雖然結果顯示快速組在疲勞產生前雖達到最多的伏地挺身次數(快速組次數高於中速與慢速1.34與1.33倍)，但肌肉訓練成效小；反觀慢速組可獲得最長持續力(慢速組持續時間高於快速組與中速組1.20與1.24倍)且對各肌群訓練也可獲得最大的活化成效。
基於以上的結果，快速組的關節受力大、肌肉訓練成效小，但節省時間，適用於如軍事訓練等特定次數要求的訓練；而慢速組的關節受力小、各肌肉訓練成效最於顯著，因此對於上肢強化而言放慢伏地挺身速度是一種最佳的選擇。

In recent years, fitness training and bodybuilding have become increasingly popular and push-up exercises are commonly performed to strengthen the upper extremity muscles. Knowledge of kinematics and kinetics may be helpful in preventing injuries if the shear forces of upper extremity can be reduced. Therefore, the purpose of this study is first to investigate the effect of different push-up speeds on joint loading of upper extremity. Fourteen healthy males participated in this investigation. Each subject performed push-ups at three different speeds (i.e., fast: 7 push-ups / 10 s; regular: 5 push-ups / 10 s; and slow: 4 push-ups / 10 s). In a motion analysis laboratory, the Expert Vision motion system with eight 240 fps cameras and 1000 Hz Kistler force plates were used to measure relative joint positions and ground reaction forces. The results showed that the peak elbow medial shear force and compression force in the fast group were 1.35 and 1.23 times greater than those in the slower group, respectively, while the peak anterior and compression forces at the shoulder in the fast group were 1.24 and 1.28 times those in the slower group, respectively. In addition, the peak elbow valgus moment, elbow extension moment, elbow pronation moment, shoulder flexion moment and shoulder adduction moment at fast push-up speed were 1.63, 1.34, 1.41, 1..36 and 1.37 times greater than at slow speed, respectively. Therefore, these increases in the joint force and moment can be harmful to the joints of upper extremity.
Furthermore, the relationship between the push-up speed and upper extremity fatigue is also not well understood. Accordingly, the present study investigated the effect of the push-up speed on the maximum possible number of push-up repetitions until fatigue and the upper-extremity muscle activity, respectively, in order to identify suitable push-up strategies for upper-extremity muscular strengthening. Fifteen healthy males participated in the study. Each subject performed push-ups at three different speeds until fatigued. The muscle activity signals were measured during the push-up tests via surface electromyography. The strengthening effect of the push-up exercises was evaluated by measuring the myodynamic decline rate at the shoulder, elbow and wrist joints using an isokinetic dynamometer. The results showed that the maximum possible number of push-up repetitions at the fast push-up speed was around 1.34 and 1.33 times higher than that at the regular push-up speed or slow push-up speed, respectively. However, the endurance time (i.e., the time to fatigue) at the slow push-up speed was around 1.20 and 1.24 times longer than that at the fast push-up speed or regular push-up speed, respectively. Finally, at the slow push-up speed, the total muscle activations in the triceps brachii, biceps brachii, anterior deltoid, pectoralis major, and posterior deltoid, respectively, were 1.47, 2.43, 1.42, 1.48, and 1.91 times higher than those at the fast push-up speed. Therefore, the experimental results suggest that push-ups should be performed at a faster speed when the aim is to achieve a certain number of repetitions, but should be performed at a slower speed when the aim is to strengthen the upper extremity muscles.

An, K.N., Browne, A.O., Korinek, S., Tanaka, S., Morrey, B.F., Three-dimensional kinematics of glenohumeral elevation. J. Orthop. Res. 9, 143-9. 1991.
An, K.N., Chao, E.Y., Morrey, B.F. Donkers, M.J., Intersegmental elbow joint load during pushup. Biomed. Sci. Instrum. 28, 69-74. 1992.
An, K.N., Korinek, S.L., Kilpela, T., Edis, S., Kinematic and kinetic analysis of push-up exercise. Biomed. Sci. Instrum. 26, 53-7. 1990.
Andrews, J.R., Wilk, K.E., The Athlete's shoulder, Churchill Livingstone, New York, 1994.
Bhatia, D.N., De Beer, J.F., Van Rooyen, K.S., Lam, F. Du Toit, D.F., The "bench-presser's shoulder": an overuse insertional tendinopathy of the pectoralis minor muscle. Br J. Sports Med. 41, e11. 2007.
Blackard, D.O., Jensen, R.L., Ebben, W.P., Use of EMG analysis in challenging kinetic chain terminology. Med. Sci. Sports Exerc. 31, 443-8. 1999.
Bowman, T.G., Hart, J.M., Mcguire, B.A., Palmieri, R.M. Ingersoll, C.D., A functional fatiguing protocol and deceleration time of the shoulder from an internal rotation perturbation. J. Athl. Train. 41, 275-9. 2006.
Callaway, G.H., Field, L.D., Deng, X.H., Torzilli, P.A., O'brien, S.J., Altchek, D.W. Warren, R.F., Biomechanical evaluation of the medial collateral ligament of the elbow. J. Bone Joint Surg. Am. 79, 1223-31. 1997.
Carpenter, J.E., Blasier, R.B., Pellizzon, G.G., The effects of muscle fatigue on shoulder joint position sense. Am. J. Sports Med. 26, 262-5. 1998.
Chapman, D.W., Newton, M., Mcguigan, M., Nosaka, K., Effect of lengthening contraction velocity on muscle damage of the elbow flexors. Med. Sci. Sports Exerc. 40, 926-33. 2008.
Chattanooga, Kin-Com: Clinical Desk Reference, Chattanooga Group, Chattanooga Group Inc. TN, 1995.
Chou, P.H., Chou, Y.L., Lin, C.J., Su, F.C., Lou, S.Z., Lin, C.F., Huang, G.F., Effect of elbow flexion on upper extremity impact forces during a fall. Clin. Biomech. 16, 888-94. 2001.
Chou, P.H., Lin, C.J., Chou, Y.L., Lou, S.Z., Su, F.C., Huang, G.F., Elbow load with various forearm positions during one-handed pushup exercise. Int. J. Sports Med. 23, 457-62. 2002.
Chou, P.H., Lou, S.Z., Chen, H.C., Chiu, C.F., Chou, Y.L., Effect of various forearm axially rotated postures on elbow load and elbow flexion angle in one-armed arrest of a forward fall. Clin. Biomech. 24, 632-636. 2009.
Chou, P.H., Lou, S.Z., Chen, S.K., Chen, H.C., Hsia, T.H., Liao, T.L. Chou, Y.L., Elbow load during different types of bench-press exercise. Biomed. Eng-App Bas. C. 20, 185-189. 2008a.
Chou, P.H., Lou, S.Z., Chen, S.K., Chen, H.C., Wu, T.H., Chou, Y.L., Biomechanical analysis of the elbow joint loading during push-up. Biomed. Eng-App Bas. C. 20, 197-204. 2008b.
Cogley, R.M., Archambault, T.A., Fibeger, J.F., Koverman, M.M., Youdas, J.W., Hollman, J.H., Comparison of muscle activation using various hand positions during the push-up exercise. J. Strength Cond. Res. 19, 628-33. 2005.
OrthoTrak Full Body Gait Analysis-Reference Manual, Motion Analysis Corporation, California, 1993.
Cram, J.R., Kasman, G.S., Holtz, J., Introduction to surface electromyography, Aspen Publishers, Gaithersburg, Md., 1998.
Delagi, E.F., Perotto, A., Iazzetti, J., Morrison, D., Anatomical Guide For The Electromyographer: The Limbs, Charles C. Thomas, New York, 1981.
Dempster, W.T., Space requirements of the seated operator, Dayton. 1995.
Donkers, M.J., An, K.N., Chao, E.Y., Morrey, B.F., Hand position affects elbow joint load during push-up exercise. J. Biomech. 26, 625-32. 1993.
Duffey, M.J., Challis, J.H., Fatigue effects on bar kinematics during the bench press. J. Strength Cond. Res. 21, 556-60. 2007.
Ebaugh, D.D., Mcclure, P.W., Karduna, A.R., Effects of shoulder muscle fatigue caused by repetitive overhead activities on scapulothoracic and glenohumeral kinematics. J. Electromyogr. Kinesiol. 16, 224-35. 2006.
Garg, A., Beller, D., One-handed dynamic pulling strength with special reference to speed, handle height and angles of pulling. Int. J. Ind. Ergon., 6, 231-240. 1990.
Gouvali, M.K., Boudolos, K., Dynamic and electromyographical analysis in variants of push-up exercise. J. Strength Cond. Res. 19, 146-51. 2005.
Haubert, L.L., Gutierrez, D.D., Newsam, C.J., Gronley, J.K., Mulroy, S.J., Perry, J., A comparison of shoulder joint forces during ambulation with crutches versus a walker in persons with incomplete spinal cord injury. Arch. Phys. Med. Rehabil. 87, 63-70. 2006.
Haug, E.J., Computer aided kinematics and dynamics of mechanical systems, Allyn and Bacon, Boston, 1989.
Haug, E.J., Intermediate dynamics, Englewood Cliffs, Prentice Hall, N.J. 1992.
Kakwani, R.G., Matthews, J.J., Kumar, K.M., Pimpalnerkar, A., Mohtadi, N., Rupture of the pectoralis major muscle: surgical treatment in athletes. Int. Orthop. 31, 159-63. 2007.
Koontz, A.M., Cooper, R.A., Boninger, M.L., Souza, A.L., Fay, B.T., Shoulder kinematics and kinetics during two speeds of wheelchair propulsion. J. Rehabil. Res. Dev. 39, 635-49. 2002.
Kretzler, H.H., Jr. Richardson, A.B., Rupture of the pectoralis major muscle. Am. J. Sports Med. 17, 453-8. 1989.
Lee, H.M., Liau, J.J., Cheng, C.K., Tan, C.M., Shih, J.T., Evaluation of shoulder proprioception following muscle fatigue. Clin. Biomech. 18, 843-847. 2003.
Lee, T.Q., Mcmahon, P.J., Shoulder biomechanics and muscle plasticity: implications in spinal cord injury. Clin. Orthop. Relat. Res. S26-36. 2002.
Lou, S., Lin, C.J., Chou, P.H., Chou, Y.L., Su, F.C., Elbow load during pushup at various forearm rotations. Clin. Biomech. 16, 408-14. 2001a.
Lou, S.Z., Lin, C.J., Chou, P.H., Chou, Y. L., Su, F.C., Elbow load during pushup at various forearm rotations. Clin. Biomech. 16, 408-414. 2001b.
Mikawa, Y., Watanabe, R., Fuse, K., Quadriplegia caused by push-up exercises. Arch. Orthop.Trauma Surg. 113, 174-5. 1994.
Morrey, B.F., Complex instability of the elbow. Instr. Course Lect. 47, 157-64. 1998.
Morrey, B.F., An, K.N., Stormont, T.J., Force transmission through the radial head. J. Bone Joint Surg. Am. 70, 250-6. 1988.
Morrey, B.F., Tanaka, S., An, K.N., Valgus stability of the elbow. A definition of primary and secondary constraints. Clin. Orthop. Relat. Res. 187-95. 1991.
Mullaney, M.J., Mchugh, M.P., Donofrio, T.M., Nicholas, S.J., Upper and lower extremity muscle fatigue after a baseball pitching performance. Am. J. Sports Med. 33, 108-13. 2005.
Myers, J.B., Guskiewicz, K.M., Schneider, R.A., Prentice, W.E., Proprioception and neuromuscular control of the shoulder after muscle fatigue. J. Athl. Train. 34, 362-367. 1999.
Newsam, C.J., Lee, A.D., Mulroy, S.J., Perry, J., Shoulder EMG during depression raise in men with spinal cord injury: the influence of lesion level. J. Spinal Cord Med. 26, 59-64. 2003.
O'driscoll, S.W., Morrey, B.F., Korinek, S., An, K.N., Elbow subluxation and dislocation. A spectrum of instability. Clin. Orthop. Relat. Res. 186-97. 1992.
Petilon, J., Carr, D.R., Sekiya, J.K., Unger, D.V., Pectoralis major muscle injuries: evaluation and management. J. Am. Acad. Orthop. Surg. 13, 59-68. 2005.
Regan, W.D., Korinek, S.L., Morrey, B.F., An, K.N., Biomechanical study of ligaments around the elbow joint. Clin. Orthop. Relat. Res. 170-9. 1991.
Robertson, D.G.E., Research methods in biomechanics, Champaign, IL, Human Kinetics. 2004.
Sharkey, N.A., Marder, R.A., The rotator cuff opposes superior translation of the humeral head. Am. J. Sports Med. 23, 270-5. 1995.
Stewart, O.J., Peat, M., Yaworski, G.R., Influence of resistance, speed of movement, and forearm position on recruitment of the elbow flexors. Am. J. Phys. Med. 60, 165-79. 1981.
Tripp, B.L., Boswell, L., Gansneder, B.M., Shultz, S.J., Functional Fatigue Decreases 3-Dimensional Multijoint Position Reproduction Acuity in the Overhead-Throwing Athlete. J. Athl. Train. 39, 316-320. 2004.
Tripp, B.L., Yochem, E.M., Uhl, T.L., Functional fatigue and upper extremity sensorimotor system acuity in baseball athletes. J. Athl. Train. 42, 90-8. 2007.
Tsai, N.T., Mcclure, P.W., Karduna, A.R., Effects of muscle fatigue on 3-dimensional scapular kinematics. Arch. Phys. Med. Rehab. 84, 1000-1005. 2003.
Veeger, H.E., Rozendaal, L.A., Van Der Helm, F.C., Load on the shoulder in low intensity wheelchair propulsion. Clin. Biomech. 17, 211-8. 2002.
Winter, D.A., Biomechanics and motor control of human movement, Wiley, New York, 1990.
Woltring, H.J., A fortran package for generalized crossvalidatory spline smoothing and differentiation. Adv. Eng. Soft. 8, 104-113. 1986.
Wu, G., Van Der Helm, F.C.T., Veeger, H.E.J., Makhsous, M., Van Roy, P., Anglin, C., Nagels, J., Karduna, A.R., Mcquade, K., Wang, X.G., Werner, F.W., Buchholz, B., ISB recommendation on definitions of joint coordinate systems of various joints for the reporting of human joint motion - Part II: shoulder, elbow, wrist and hand. J. Biomech. 38, 981-992. 2005.