The Babolat advertising here mentions the durability with players such as Rafael Nadal. According to google, durability means "the ability to withstand wear, pressure, or damage". I am not sure what it means here: it does not certainly mean too muscular because muscle is very expensive cell in terms of natural metabolism rate aka energy needed per time unit. Too muscular person cannot continue playing because of getting tired during a long run so not durable.
Now I am trying to make the connection to durability and monofilament strings. What do the two things have to do with each other? I cannot see the connection. Please, explain:
Why should durable tennis players use strings of monofilament?