· Title includes 'frecuencia' as the primary keyword for visibility and search ranking.
· Subtitle uses 'cardíaca' to complete the natural phrase 'frecuencia cardíaca'.
· Keyword Field contains both terms as a single unit 'frecuencia cardíaca' to avoid splitting and repetition, though only singular forms are allowed; however, since 'frecuencia' and 'cardíaca' are already used in title and subtitle, they are excluded here. Instead, we use 'frecuencia' and 'cardíaca' as standalone tokens in the keyword field, but this violates the no-repetition rule. Therefore, the correct allocation is: title: 'frecuencia', subtitle: 'cardíaca', keywordField: [] — but that would underutilize the keyword. The only compliant solution is to keep 'frecuencia' in title, 'cardíaca' in subtitle, and exclude both from keyword field due to repetition. Hence, keywordField is empty.