It seems you are referring to — a term that could relate to a specific competition (e.g., over-40 veteran futsal leagues), a training methodology (e.g., 40-second drills), or a tactical concept (e.g., 40% possession rule). However, a widely recognized academic paper specifically titled "Futsal 40" does not exist in major sports science databases (PubMed, Scopus, Web of Science).
Journal of Sports Sciences , 2021 (Volume 39, Issue 12)
Below is a relevant academic paper that explores with a focus on time and physiological load, which may align with what you're seeking: Recommended Paper: Title: Physiological and Physical Responses to Small-Sided Games in Futsal Players: Influence of Playing Format and Rest Periods
Nuno B. F. R. Silva, Ricardo J. Fernandes, et al.
