Shares of Planet Fitness (PLNT) gained in after-hours trading Tuesday after the low-cost gym operator posted its quarterly results.

 Q1 RESULTS: Planet Fitness reported first quarter adjusted earnings per share of 15c against estimates of 13c, and revenue of $83.3M versus expectations for $78.7M. Total same-store sales rose 6.8% for the quarter, and the company opened 48 new franchise locations during the period to bring total store count to 1,171.

CONCEPT RESONATING WITH CASUAL USERS: Chief Executive Chris Rondeau commented, "Awareness of our affordable, non-intimidating fitness offering continues to increase driven by the combination of our powerful national advertising strategy and continued unit expansion. We remain confident that we have a significant runway for growth based on how well our concept continues to resonate with the large population of casual and first time gym users."

GUIDANCE BOOST: Planet Fitness raised its full-year 2016 financial outlook, saying it now expects adjusted EPS of 62c-65c as compared to the previous 60c-63c view, and revenue of $360M-$370M as compared to $355M-$365M previously. The company reiterated its forecast for same store sales growth in the mid-single digit range, and between 210-220 new franchised store openings. $20M

BUYBACK PLAN: In addition to the "beat and raise" quarter, Planet Fitness also announced a new $20M share repurchase plan, with Rondeau citing confidence in the company's strong brand and asset-light model.

PRICE ACTION: Shares of Planet Fitness rose 3.71% to $16.20 in after-hours trading