When you write a research article, you don’t have much say in the major headings, which are typically Introduction, Materials and Methods, Results, and Discussion, or some similar wording your target journal prefers. However, you get to decide how to divide each major section into subsections and give them subheadings. One thing to keep in mind is that you should try to use the same style for all the subheadings within a major section. This will help present a clear structure of your study for the readers to follow.
Imagine we have a study where our Results section is divided into three subsections:
- Expression of protein X in metastatic colorectal cancer
- Protein X promotes epithelial-mesenchymal transition of colorectal cancer cells
- Protein X affected metastasis in a xenograft model
Here the first subheading is only a sentence fragment while the next two are complete sentences. The second subheading uses the present tense while the third subheading uses the past tense. Further, the second subheading states the specific results (i.e., promotes epithelial-mesenchymal transition) while the other subheadings don’t tell the readers what to expect (Is the expression higher or lower? How is metastasis affected?). We can rewrite these subheadings so they are in a consistent style:
- Protein X is upregulated in metastatic colorectal cancer
- Protein X promotes epithelial-mesenchymal transition of colorectal cancer cells
- Protein X promotes metastasis in a xenograft model
Now all subheadings are in complete sentences and present the specific results. This way, a reader can have some basic idea of the major results even without reading the entire section. Since the subheadings are conclusions of the results, we usually use the present tense. If we don’t want to use complete sentences, we could rewrite like this:
- Elevated expression of protein X in metastatic colorectal cancer
- Promotion of epithelial-mesenchymal transition of colorectal cancer cells by protein X
- Promotion of tumor metastasis in a xenograft model by protein X
This set of subheadings conveys the same meaning. Whether to use complete sentences for subheadings is a personal preference. Some people might write like this:
- Expression of protein X in metastatic colorectal cancer
- Effect of protein X on epithelial-mesenchymal transition of colorectal cancer cells
- Effect of protein X on tumor metastasis in a xenograft model
However, the readers will not get as much information from these subheadings as from the two previous sets of subheadings, so this way is less preferred in an original research article, but it is still better than all subheadings in different styles.
If you have subheadings in other sections, you can use a different style than the one used for the Results section. For example, the subheadings in the Methods section are often just names of the assays to be described. You can also think of figure titles as subheadings, so all titles of your figures should be written in the same style. If you use complete sentences to summarize the findings of the figures, you can use the present tense.