Seeing effort
a test of the coach’s accuracy rates in predicting the number of repetitions in reserve before reaching task failure
DOI:
https://doi.org/10.51224/SRXIV.165Keywords:
resistance-training, repetitions in reserve, task-failure, personal-training, coach’s eyeAbstract
Background: A key role of resistance training (RT) coaches is to personalize programs based on their trainees’ abilities and goals. Specifically, coaches often assess how many repetitions in reserve (RIR) trainees have until task-failure. Coaches can then modify the number of repetitions assigned per set accordingly. However, coaches’ ability to predict the number of RIR is unknown.
Methods: We recruited 259 certified RT coaches, who were randomly assigned to watch a video of one of eight models. The models performed two sets of barbell squats, followed by two sets of preacher bicep curls, using 70% or 80% of their 1RM, to task-failure. Coaches predicted the models’ RIR at 33%, 66% and 90% of the total number of repetitions that the models completed in each set. We fitted a linear mixed model with a range of predictors to the raw and absolute prediction errors as the outcomes (i.e., signed and unsigned predicted minus actual repetitions to task-failure).
Results: The overall average number of repetitions completed by the models was 13.9. The overall average absolute errors were 4.8, 2.0, and 1.2 repetitions, for the 33%, 66% and 90% time-points, respectively. Coaches increased the absolute prediction error for the bicep curl compared to the squat (1.43, 95% CI [1.13, 1.74]), whereas the absolute prediction error decreased for heavier loads (-1.17, 95% CI [-2.16, -0.19]), and in the second set of each exercise (-1.20, 95%CI [-1.38, -1.02]). Surprisingly, coaches’ years of experience had a negligible effect on the absolute error (-0.020, 95% CI [-0.039, -0.0007]). Finally, coaches underestimated the RIR of trainees at early prediction time-points, but corrected this bias and even slightly overestimated the RIR at later time-points.
Conclusions: Prior coaching experience does not seem to play a substantial role in RIR predictions. However, even short-term exposures to new trainee’s performing different exercises can lead to substantial improvements in coaches’ RIR predictions.
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Copyright (c) 2022 Aviv Emanuel, Itai Har-Nir, Uri Obolski, Israel Halperin
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