How to use it
Every coaching cue gets tested the same way: film three attempts with cue A and three with cue B, compare on video, keep what wins for you. "External" cues are a starting point, not a law.
How sure we are
S Evidence: strong. Large trials or many studies, pointing the same way.
Sources
two meta-analyses on attentional focus disagree; a bias-corrected meta-analysis found "let the athlete choose" isn't a shortcut.
Not medical, legal or financial advice.