Research Group in Physical Activity Nutrition and Health (GRAFAiS), Institut Nacional d'Educació Física de Catalunya (INEFC), Universitat de Barcelona (UB), Barcelona, Spain.
Int J Sports Physiol Perform. 2023 Sep 21;18(12):1380-1389. doi: 10.1123/ijspp.2023-0183. Print 2023 Dec 1.
To verify whether training the iron cross (IC) with assistive devices (herdos; HIC) and added external load (LHIC) to equate the moments of force developed on the rings could be considered an intermediate step between the nonoverloaded herdos situation (HIC) and the IC performed on the rings.
Relative levels of surface electromyography (sEMG) activity were normalized with respect to a standing IC before comparing gymnasts who can perform the IC on the rings (achievers) and gymnast who cannot (nonachievers) in the 2 herdos conditions (HIC and LHIC). Seven muscles were chosen for sEMG analysis, namely, pectoralis major (PM), latissimus dorsi, teres major, lower trapezius, serratus anterior, biceps brachii (BB), and triceps brachii. Additionally, 3 indices were calculated to measure levels of coactivation: Elbowidx, Scapulaidx, and Shoulderidx.
The bigger magnitude of differences in sEMG activity among situations was found for the PM and BB (F ≥ 30.7; P < .001). When comparing the global and the PM, teres major, BB, and triceps brachii activity across groups, nonachievers activated their musculature to a greater extent than the achievers independently of the herdos situation (P ≤ .046). Achievers' Elbowidx was the only index that was significantly higher (P ≤ .005) in the IC in comparison to LHIC and HIC.
sEMG activity of PM and BB was particularly sensitive between situations, independently of the level of achievement. We recommend training the IC by adding external load in the herdos situation to increase muscle activity to levels closer to the rings situation but avoiding the potential factor of injuries.
验证使用辅助器械（herdos；HIC）和附加外部负载（LHIC）来训练铁十字（IC），以使其与环上产生的力的力矩相等，是否可以被认为是非过载 herdos 情况（HIC）和在环上进行的 IC 之间的中间步骤。
在比较能够在环上进行 IC 的体操运动员（成就者）和不能在环上进行 IC 的体操运动员（非成就者）时，将相对于站立 IC 之前的表面肌电图（sEMG）活动的相对水平进行归一化，在 2 种 herdos 条件（HIC 和 LHIC）下。选择了 7 块肌肉进行 sEMG 分析，分别为胸大肌（PM）、背阔肌、大圆肌、下斜方肌、前锯肌、肱二头肌（BB）和肱三头肌。此外，计算了 3 个指标来衡量共同激活水平：Elbowidx、Scapulaidx 和 Shoulderidx。
在 PM 和 BB 中发现了不同情况下 sEMG 活动差异的幅度更大（F≥30.7；P<.001）。当比较各组的整体和 PM、大圆肌、BB 和肱三头肌的活动时，非成就者比成就者更广泛地激活他们的肌肉，而与 herdos 情况无关（P≤.046）。在 IC 中，成就者的 Elbowidx 是唯一一个明显高于 LHIC 和 HIC 的指标（P≤.005）。
PM 和 BB 的 sEMG 活动在不同情况下特别敏感，与成就水平无关。我们建议在 herdos 情况下通过增加外部负载来训练 IC，以增加肌肉活动，使其更接近环的情况，但要避免潜在的受伤因素。
