Dello Iacono Antonio, Henry Scott, Ben-Ari Asaf, Halperin Israel, Carey Laura
Division of Sport, Exercise and Health, School of Health and Life Sciences, Sport and Physical Activity Research Institute (SPARI), University of the West of Scotland, Hamilton, UK.
Department of Health Promotion, School of Public Health, Faculty of Medical and Health Sciences, Tel Aviv University, Tel Aviv, Israel.
Sports Med Open. 2025 Jul 9;11(1):83. doi: 10.1186/s40798-025-00890-1.
Resistance training (RT) coaches regularly instruct their trainees to terminate a set when the repetition velocity drops below a certain threshold, aligned with the principles of velocity loss in velocity-based training (VBT). However, absent of a velocity-tracking device, coaches are required to detect velocity loss through observation-a topic that has never been studied. Here, we assess the accuracy of RT coaches in detecting when trainees reach specific repetition velocity loss thresholds.
Twenty RT coaches participated in a single experimental session. They observed videos of two trainees completing sets of the barbell bench press and barbell back squat exercises, using three loads (45%, 65%, and 85% of 1 repetition-maximum [1RM]), and recorded from two views (front and side). We asked them to detect when repetition velocity dropped below two velocity loss thresholds (20% and 40% relative to their first repetition). We examined whether load, velocity loss threshold, view, mental fatigue, and gaze strategy (bar or no-bar tracking) influenced accuracy. We compared outcomes using a negative binomial generalized mixed-effects model.
The average absolute error across all conditions was 2.6 repetitions. Coaches improved their accuracy (negative estimates indicate reduced error) when observing a higher velocity loss threshold (40% vs 20%; - 1.8, 95%CI [- 2.3, - 1.3]); observing heavier loads (- 0.8, 95% CI [- 1.5, - 0.1] for 65% 1RM, and - 3, 95%CI [- 3.4, - 2.6] for 85% 1RM compared to 45% 1RM); and employing a bar tracking gaze strategy compared to a no-bar strategy (- 1.7, 95%CI [- 2.7, - 0.4]). In contrast, point of view and mental fatigue had a negligible effect.
While coaches detect velocity loss with some degree of accuracy, their error rates vary depending on the threshold, load, and gaze strategy. These factors should be considered when using perceived velocity loss in practice.
抗阻训练（RT）教练在基于速度的训练（VBT）中，通常会按照速度损失原则，指导学员在重复速度降至特定阈值以下时终止一组训练。然而，在没有速度追踪设备的情况下，教练需要通过观察来检测速度损失，而这一主题从未被研究过。在此，我们评估RT教练检测学员达到特定重复速度损失阈值的准确性。
20名RT教练参与了一次实验。他们观看了两名学员完成杠铃卧推和杠铃后蹲练习组的视频，使用了三种负荷（1次重复最大值[1RM]的45%、65%和85%），并从两个视角（正面和侧面）进行录制。我们要求他们检测重复速度何时降至两个速度损失阈值（相对于第一次重复的20%和40%）。我们研究了负荷、速度损失阈值、视角、精神疲劳和注视策略（杠铃或无杠铃追踪）是否会影响准确性。我们使用负二项广义混合效应模型比较结果。
所有条件下的平均绝对误差为2.6次重复。当观察到更高的速度损失阈值（40%对比20%；-1.8，95%置信区间[-2.3，-1.3]）、观察到更重的负荷（与45% 1RM相比，65% 1RM时为-0.8，95%置信区间[-1.5，-0.1]，85% 1RM时为-3，95%置信区间[-3.4，-2.6]）以及采用杠铃追踪注视策略而非无杠铃策略（-1.7，95%置信区间[-2.7，-0.4]）时，教练的准确性有所提高（负估计值表示误差减少）。相比之下，视角和精神疲劳的影响可忽略不计。
虽然教练能够在一定程度上准确检测速度损失，但其错误率会因阈值、负荷和注视策略的不同而有所变化。在实际应用感知速度损失时，应考虑这些因素。
