Consider this sentence:

He hurt his back playing squash.

What is the role of playing squash here?

Is it a reduced adverbial clause or a present participle phrase? If so, why isn't there a comma before it? (I was taught that there should be a comma there)

  • Without addressing for the moment the reduced clause or the elided while, if you were taught that a comma is required after back, you were very probably taught English by someone who doesn't really speak English. There is absolutely not such a requirement in a short sentence like this one, and even in a longer one, that "rule" was created by nincompoops and forgotten a century ago. Commented Aug 1, 2017 at 23:38
  • "Adverbial" and "participle" name two different aspects: syntactic function and internal structure. This is a participle clause (I don't know what you mean by 'reduced') acting as an adverbial modifying the main clause: it indicates both a) the 'scene' or occasion of the main-clause event and b) the subject's activity which contributed to the out. Commented Aug 2, 2017 at 0:46
  • @StoneyB Thank you for your comment. What do you think about these web pages: 1. quickanddirtytips and purdue.edu. The authors both more or less say that if a participle phrase acts as an adverb at the end of the sentence, it needs a comma before it. Are they incorrect?
    – AndyD
    Commented Aug 2, 2017 at 8:19
  • @user52139 Punctuation is orthography, not grammar. About the only consistently observed 'rule' with commas is that 'supplements'--elements are not integrated into the syntax of a clause--should be bracketed off with commas. Beyond that you're on your own. Commented Aug 2, 2017 at 8:36

2 Answers 2


Light can be described either as waves or as particles, depending on what behaviour you want to predict. In the same way, playing squash can be described as either adverbial or participial, depending on whether you want to look at the construction of the clause itself (its head is a participle), or the role of the clause in the complete sentence (it acts as an adverb).

Guidelines about punctuation can be helpful... but you need to use the appropriate guidelines. When considering punctuation of the sentence as a whole, you need to consider the role of the clause in the complete sentence (it acts as an adverb), rather than how the clause is constructed.

The quick and dirty tips link that you provided in your comment about the comma does not seem to be about grammar. The Purdue link that you provided relates to adjectival usages of participle phrases.

Adjectival usages affect just one of the nouns or pronouns in the sentence. This is an adverbial usage, which affects the whole sentence. Here is some advice on punctuation for adverb clauses:

A comma is usually not necessary when the adverb clause follows the main clause.


He hurt his back playing squash.

Subject = He.

Verb= hurt.

Object = his back. (answers hurt what ?).

Adverbial phrase = when or how he hurt it.

Playing acts as an adjective modifying or adding more information about what he was playing. (He was playing squash not soccer or tennis).

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