External torque as a factor to modify load in abdominal curl-up exercises
Study aim: the aim of our study was to evaluate electromyography (EMG) activity in exercises where the load to the muscles is determined by the external torque. In a part of the exercises, we changed the value of the external force, while in the other we modified the length of the lever arm at which the force was applied. Material and methods: the study was carried out on a group of 12 subjects (21 ± 2 years, 61 ± 4.8 mass, 172 ± 5 cm height). Electromyographic activity of the rectus abdominis (RA) muscle was evaluated by recording the EMG signal. The length of the lever arm of the external force was changed by using four different positions of the upper limbs, whereas the magnitude of the external force was changed through adding the weights of 0.5, 1.0, and 1.5 kg. The data recorded were normalized with respect to EMG activity measured under maximum voluntary contraction (MVC) conditions. Results: it was found that the change of the lever arm at which the force was applied (any change in the position of the upper limbs) causes a change in EMG activity in each part of the RA muscle from ca. 50% to ca. 100% MVC (p < 0.001). Further, the change in the external load changes statistically significantly the EMG activity only in the left upper part of the RA muscle (p < 0.05). Conclusions: activity in the RA muscle that increased for longer lever arms of the external force, offers opportunities for changing the load used during the exercise in a manner that is safe for the vertebral column.
- 1. Andersson E.A., J. Nilsson, Z. Ma, A. Thorstensson (1997) Abdominal and hip flexor muscle activation during various training exercises. Eur. J. Appl. Physiol., 75: 115-123.
- 2. Avedisian L.D.S., R.C. Kowalsky, R.C. Albro (2005) Abdominal strengthening using the AbVice machine as measured by surface electromyographic activation levels. J. Strength Cond. Res., 19: 709-712.
- 3. Axler C.T., S.M. McGill (1996) Low back loads over a variety of abdominal exercises: searching for the safest abdominal challenge. Med. Sci. Sport Exerc., 29: 804-811.
- 4. Bird M., K.M. Fletcher, A.J. Koch (2006) Electromyographic comparison of the Ab-slide and crunch exercises. J. Strength Cond. Res., 20: 436-440.
- 5. Bruggemann G.P. (2005) Sport-related spinal injuries and their prevention. In: Zatsiorsky V., ed.: Biomechanics in Sport. Oxford: Blackwell Science, pp. 550-576.
- 6. Clark K.M., L. Holt, J. Sinyard (2003) Electromyoraphic comparison of the upper and lower rectus abdominis during abdominal exercises. J. Strength Cond. Res., 17: 475-483.
- 7. De Luca C.J. (1997) The use of surface electromyography in biomechanics. J. Apll. Biomech., 13: 135-163.
- 8. Drzał-Grabiec J., S. Snela, J. Justyna Rykała, J. Podgórska, A. Truszczyńska (2014) The influence of elongation exercises on the anterior-posterior spine curvatures. Biomed. Hum. Kinet., 6: 1-4. DOI: 10.2478/bhk-2014-0001.
- 9. Escamilla R.F., E. Babb, R. DeWitt (2006) Electromyographic analysis of traditional and nontraditional abdominal exercises: implications for rehabilitation and training. Phys. Ther., 86: 656-671.
- 10. Grabara M. (2013) Effects of 8-months yoga training on shaping the spine in people over 55. Biomed. Hum. Kinet., 5: 59-64. DOI: 10.2478/bhk-2013-0009.
- 11. Juker D., S.M. McGill, P. Kropf (1998) Quantitative intramuscular myoelectric activity of lumbar portions of psoas and the abdominal wall during a wide variety of tasks. Med. Sci. Sport Exerc., 30: 301-310.
- 12. Lehman G.J., S.M. McGill (2001) Quantification of the differences in electromyographic activity magnitude between the upper and lower portions of the rectus abdominis muscle during selected trunk exercises. Phys. Ther., 81: 1096-1101.
- 13. Nachemson A.L. (1976) The lumbar spine an orthopaedic challenge. Spine, 1: 59-71.
- 14. Ng J.K.-F., V. Kippers, C.A. Richardson (1998) Muscle fiber orientation of abdominal muscles and suggested surface EMG electrode positions. Electomyo. Clin. Neur., 38: 51–58.
- 15. Nikolaidis P. (2010) Core stability of male and female football players. Biomed. Hum. Kinet., 2: 30-33. DOI: 10.2478/v10101-010-0007-9.[Crossref]
- 16. Rutkowska-Kucharska A., A. Szpala, E. Pieciuk (2009) Symmetry of muscle of activity during abdominal exercises. Acta Bioeng. Biomech., 11: 25-30.
- 17. Rutkowska-Kucharska A., A. Szpala (2010) Electromyographic muscle activity in curl-up exercises with different positions of upper and lower extremities. J. Strength Cond. Res., 24: 3113-3139. DOI:10.1519/JSC.0b013e3181ddb308[Crossref]
- 18. Salvo V.D., A. Parisi, C. Buonomini, F. Iellamo (2002) Abdominal and lumbar muscles strength gains using two types of sit-up exercises. Biol. Sport, 19: 303-328.
- 19. Sternlicht E., S. Rugg (2003) Electromyographic analysis of abdominal muscle activity using portable abdominal exercise devices and a traditional crunch. J. Strength Cond. Res., 17: 463-468.
- 20. Sternlicht E., S. Rugg, M.D. Bernstein (2005) Electromyographic analysis and comparison of selected abdominal training devices with a traditional crunch. J. Strength Cond. Res., 19: 157-162.
- 21. Vera-Garcia F.J., B. Flores-Parodi, J. Elvira (2008) Influence of trunk curl-up speed on muscular recruitment. J. Strength Cond. Res., 22: 684-690. DOI: 10.1519/JSC.0b013e31816d5578. [Crossref]