Jan Pruckl1, Miriam Kalichová1
1Masaryk University, Faculty of Sports Studies, Brno, Czech Republic
Surface EMG Verification of Oblique Muscle Activation During a Forcemeter-Based Unilateral Isometric Pulling Task
Sport Mont 2026, 24(3), Ahead of Print | DOI: 10.26773/smj.261013
Abstract
Muscle imbalances in trunk rotators may impair function and contribute to injury risk, yet practical field-based assess- ment methods remain limited. This pilot methodological study explored whether a unilateral isometric pulling task per- formed with a digital forcemeter elicits measurable trunk rotator activation and whether force output is associated with muscle activation. Fifteen physically active adults performed standardized unilateral isometric pulling under stable sitting support while surface EMG recorded activation of the external and internal oblique muscles. Force output was recorded continuously with a digital forcemeter. Within-subject associations between synchronized force and sEMG signals during the pulling task were evaluated using Spearman correlation coefficients, calculated separately for each participant, hand, and muscle, and then summarized as median values with interquartile ranges. Median within-subject correlations were observed between pulling force and ipsilateral external oblique (EO) and internal oblique (IO) activa- tion (EO: R=0.67, IQR=0.36; IO: R=0.64, IQR=0.31), as well as for contralateral muscles (EO: R=0.69, IQR=0.28; IO: R=0.63, IQR=0.34). These findings suggest that the task elicits measurable oblique muscle activation and that force and sEMG signals covary within trials under the tested conditions. Further studies are required to determine test–retest reliability, validity, and potential diagnostic utility.
Keywords
electromyography, muscle strength, dynamometer, athletic injuries, physical examination
View full article
(PDF – 1830KB)
References
Bigolin, A. V., Jost, R. T., Franceschi, R., Wermann, R., Falcão, R., Do Pinho, A. S., … Cavazzola, L. T. (2020). What is the best method to assess the abdominal wall? Restoring strength does not mean functional recovery. Arquivos Brasileiros de Cirurgia Digestiva, 33, e1487. https://doi.org/10.1590/0102-672020190001e1487
Cacek, J. (2014). Fyziologie pohybové činnosti [Physiology of physical activity]. Praha, Czech Republic: Karolinum.
Čihák, R., Grim, M., Druga, R., & Fejfar, O. (2004). Anatomie [Anatomy] (3rd ed.). Praha, Czech Republic: Grada.
De Blaiser, C., Roosen, P., Willems, T., Danneels, L., Van Bossche, L., & De Ridder, R. (2018). Is core stability a risk factor for lower extremity injuries in an athletic population? A systematic review. Physical Therapy in Sport, 30, 48–56. https://doi.org/10.1016/j.ptsp.2017.08.076
Heckman, C. J., & Enoka, R. M. (2012). Motor unit. Comprehensive Physiology, 2(4), 2629–2682.
Huebner, A., Faenger, B., Schenk, P., Scholle, H. C., & Anders, C. (2015). Alteration of surface EMG amplitude levels of five major trunk muscles by defined electrode location displacement. Journal of Electromyography and Kinesiology, 25(2), 214–223. https://doi.org/10.1016/j.jelekin.2014.11.008
Jeong, J., Choi, D. H., & Shin, C. S. (2021). Core strength training can alter neuromuscular and biomechanical risk factors for anterior cruciate ligament injury. American Journal of Sports Medicine, 49(1), 183–192. https://doi.org/10.1177/0363546520972990
Kamen, G., & Gabriel, D. A. (2010). Essentials of electromyography. Champaign, IL: Human Kinetics.
Karthikbabu, S., & Chakrapani, M. (2017). Hand-held dynamometer is a reliable tool to measure trunk muscle strength in chronic stroke. Journal of Clinical and Diagnostic Research, 11(9), YC09. https://doi.org/10.7860/JCDR/2017/28105.10672
Kolář, P. (2009). Rehabilitace v klinické praxi [Rehabilitation in clinical practice]. Praha, Czech Republic: Galén.
Krobot, A., & Kolářová, B. (2011). Povrchová elektromyografie v klinické rehabilitaci [Surface electromyography in clinical rehabilitation]. Olomouc, Czech Republic: Palacký University Olomouc.
Kupa, E. J., Roy, S. H., Kandarian, S. C., & De Luca, C. J. (1995). Effects of muscle fiber type and size on EMG median frequency and conduction velocity. Journal of Applied Physiology, 79(1), 23–32. https://doi.org/10.1152/jappl.1995.79.1.23
Kuriki, H. U., de Azevedo, F. M., Takahashi, L. S. O., Mello, E. M., Filho, R. F., & Alves, N. (2011). The relationship between electromyography and muscle force. In M. Schwartz (Ed.), EMG methods for evaluating muscle and nerve function (pp. 31–54). Rijeka, Croatia: InTech. https://doi.org/10.5772/25381
Oyama, S., Yu, B., Blackburn, J. T., Padua, D. A., Li, L., & Myers, J. B. (2014). Improper trunk rotation sequence is associated with increased maximal shoulder external rotation angle and shoulder joint force in high school baseball pitchers. American Journal of Sports Medicine, 42(9), 2089–2094. https://doi.org/10.1177/036354651453687
Page, P., Frank, C. C., & Lardner, R. (2010). Assessment and treatment of muscle imbalance: The Janda approach. Champaign, IL: Human Kinetics.
Pontillo, M., Milić-Strkalj, I., & Sennett, B. (2021). Prediction of trunk injuries from core stability testing in collegiate athletes. Sports Orthopaedics and Traumatology, 37(4), 338–342. https://doi.org/10.1016/j.orthtr.2021.08.007
Southwell, D. J., Hills, N. F., McLean, L., & Graham, R. B. (2016). The acute effects of targeted abdominal muscle activation training on spine stability and neuromuscular control. Journal of NeuroEngineering and Rehabilitation, 13(1), 19. https://doi.org/10.1186/s12984-016-0126-9
Wałecka, J., Lubiatowski, P., Bręborowicz, E., Kaczmarek, P., Grygorowicz, M., & Romanowski, L. (2023). Isometric shoulder testing using a forcemeter is a reliable method of strength evaluation. Sensors, 23(22), 9106. https://doi.org/10.3390/s23229106
Zemková, E. (2019). Reliability of a novel method assessing muscle power and velocity during seated trunk rotations. Physical Activity Review, 7, 1–8. https://doi.org/10.16926/par.2019.07.01
Zemková, E., Poór, O., & Jelen, M. (2019). Between-side differences in trunk rotational power in athletes trained in asymmetric sports. Journal of Back and Musculoskeletal Rehabilitation, 32(4), 529–537. https://doi.org/10.3233/BMR-181131