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Randomized Controlled Trial
. 2023 May 22;13(1):8212.
doi: 10.1038/s41598-023-35424-w.

Myoelectric activity during electromagnetic resistance alone and in combination with variable resistance or eccentric overload

Affiliations
Randomized Controlled Trial

Myoelectric activity during electromagnetic resistance alone and in combination with variable resistance or eccentric overload

Hugo Zambrano et al. Sci Rep. .

Abstract

The purpose of this study was to compare the effects of electromagnetic resistance alone, as well as in combination with variable resistance or accentuated eccentric methods, with traditional dynamic constant external resistance exercise on myoelectric activity during elbow flexion. The study employed a within-participant randomized, cross-over design whereby 16 young, resistance-trained male and female volunteers performed elbow flexion exercise under each of the following conditions: using a dumbbell (DB); using a commercial electromagnetic resistance device (ELECTRO); variable resistance (VR) using a setting on the device that attempts to match the level of resistance to the human strength curve, and; eccentric overload (EO) using a setting on the device that increases the load by 50% on the eccentric portion of each repetition. Surface electromyography (sEMG) was obtained for the biceps brachii, brachioradialis and anterior deltoid on each of the conditions. Participants performed the conditions at their predetermined 10 repetition maximum. " The order of performance for the conditions was counterbalanced, with trials separated by a 10-min recovery period. The sEMG was synced to a motion capture system to assess sEMG amplitude at elbow joint angles of 30°, 50°, 70°, 90°, 110°, with amplitude normalized to the maximal activation. The anterior deltoid showed the largest differences in amplitude between conditions, where median estimates indicated greater concentric sEMG amplitude (~ 7-10%) with EO, ELECTRO and VR compared with DB. Concentric biceps brachii sEMG amplitude was similar between conditions. In contrast, results indicated a greater eccentric amplitude with DB compared to ELECTRO and VR, but unlikely to exceed a 5% difference. Data indicated a greater concentric and eccentric brachioradialis sEMG amplitude with DB compared to all other conditions, but differences were unlikely to exceed 5%. The electromagnetic device tended to produce greater amplitudes in the anterior deltoid, while DB tended to produce greater amplitudes in the brachioradialis; amplitude for the biceps brachii was relatively similar between conditions. Overall, any observed differences were relatively modest, equating to magnitudes of ~ 5% and not likely greater than 10%. These differences would seem to be of minimal practical significance.

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Conflict of interest statement

BJS serves on the scientific advisory board of Tonal, a manufacturer of fitness equipment. He also formerly served on the scientific advisory board of the DeLuca Foundation, an organization dedicated to fostering research and innovation in electromyography and human movement sciences. The other authors declare no competing interests in regard to this manuscript.

Figures

Figure 1
Figure 1
sEMG amplitudes for the deltoid presented across conditions and summarized across repetitions. Circles represent means and error bars represent ± one standard error calculated from bootstrap samples. sEMG Surface electromyography, EO Eccentric overload, DB Dumbbell, ELECTRO Electromagnetic resistance, VR Variable resistance.
Figure 2
Figure 2
sEMG amplitudes for the biceps brachii presented across conditions and summarized across repetitions. Circles represent means and error bars represent ± one standard error calculated from bootstrap samples. sEMG Surface electromyography, EO Eccentric overload, DB Dumbbell, ELECTRO Electromagnetic resistance, VR Variable resistance.
Figure 3
Figure 3
sEMG amplitudes for the brachioradialis presented across conditions and summarized across repetitions. Circles represent means and error bars represent ± one standard error calculated from bootstrap samples. sEMG Surface electromyography, EO Eccentric overload, DB Dumbbell, ELECTRO Electromagnetic resistance, VR Variable resistance.

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References

    1. Ahtiainen JP, Sallinen J, Häkkinen K, Sillanpää E. Inter-individual variation in response to resistance training in cardiometabolic health indicators. Scand. J. Med. Sci. Sports. 2020;30:1040–1053. doi: 10.1111/sms.13650. - DOI - PubMed
    1. Kraemer WJ, Ratamess NA, French DN. Resistance training for health and performance. Curr. Sports Med. Rep. 2002;1:165–171. doi: 10.1249/00149619-200206000-00007. - DOI - PubMed
    1. Brandenburg JP, Docherty D. The effects of accentuated eccentric loading on strength, muscle hypertrophy, and neural adaptations in trained individuals. J. Strength Cond. Res. 2002;16:25–32. - PubMed
    1. Boehringer S, Whyte DG. Validity and test-retest reliability of the 1080 quantum system for bench press exercise. J. Strength Cond. Res. 2019;33:3242–3251. doi: 10.1519/JSC.0000000000003184. - DOI - PubMed
    1. Kavanaugh, A. The role of progressive overload in sports conditioning. NSCA’s Perform. Train. J.6(1), 15–17 (2007).

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