I have been a size UK10 most of my adult life. But recently they have felt too small. In fact, most size 10 tops that I have been sent to review have felt like a squeeze. I worried I’d put on weight but I don’t think I have. Then I wondered (dreamily!) if against the odds I had suddenly grown bigger boobs. The tightness in sports UK10 tops is across the chest and upper back. But no, I’m still on the small side of small.

So I simply put it all down to aging and sports companies making their UK10s a tad smaller.

However, I have now worked out what has happened. During the recent Glasgow Triathlon Club annual spring training weekend a friend pointed out that my shoulder muscles are bigger. Normally a person who boasts skinny shoulders and arms I have trained my way to broader shoulders and almost pronounced shoulder and bicep muscles. The G-Force informs me that my lats are wider, too!

And all this must come down to swimming. For many, many months I have been swimming at least twice a week and this is not a leisurely kind of swimming. I have been swimming lots and lots of lengths and many at speed.

The result is that I have grown upper body muscles – and now my size 10 tops do not fit. In fact, I have just returned a number of small Helly Hansen running tops for review and requested the size medium.

Now at least I have the answer to what had become a little worrying. I hope that after the triathlons I can reduce the muscles so that I can return to all my favourite sports tops.