Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of fitness center operator Life Time Fitness (NYSE: LTM) were looking winded today as they fell as much as 12% in intraday trading after the company reported first-quarter results.

So what: On an absolute basis, the results from Life Time's first quarter looked pretty darn fit. Revenue for the quarter came in at $268 million, up nearly 12% from the prior year, while earnings per share finished at $0.62, up 22% from the same quarter in 2011. Growth was helped by 5.4% growth in same-center revenue for centers that had been open 13 months or longer.

Revenue for the quarter fell a bit short of Wall Street's average estimate of $271 million, but earnings per share topped the $0.61 expectation.

Now what: Similar to the current-quarter performance, Life Time's outlook for the full year looks good -- expected revenue growth of 11% and earnings-per-share growth of 23%. However, the guidance didn't live up to the high hopes of Wall Street analysts. Analysts were looking for $1.13 billion in full-year revenue and $2.75 in per-share profit. At the midpoint of its guidance, management put sales and EPS, respectively, at $1.12 billion and $2.69.

While investors may be doing some readjusting of expectations today, there's definitely a reason to temper the pessimism, because Life Time Fitness' first quarter makes it look like the company is doing a lot of good things.

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