Acute age- and gender-based physiological responses to Cardio tennis. J Strength Cond Res 28(11): 3177'3183, 2014'This study described physiological and perceptual responses to Cardio tennis for 'younger' and 'older' adult populations of both sexes for health-related outcomes. Thirty-one active participants, each with prior recreational tennis experience (~2 years) (8 younger and 8 older males, and 7 younger and 8 older females) performed preliminary testing and a 50-minute instructor-led Cardio tennis session. Cardio tennis is a conditioning-based tennis program comprised of warm-up movements, drill-based exercises (set movement and hitting games), and competitive play scenarios. Participants performed the 20-m shuttle run test to determine maximal heart rate (HR) during preliminary testing. Before, after, and 30-minute post Cardio tennis session, HR, blood pressure (BP), rate pressure product (RPP), and capillary blood lactate and glucose were determined. Furthermore, HR and pedometer-derived step counts were measured throughout, while the session was filmed and coded for technical skill. After the session, ratings of perceived exertion, enjoyment, and challenge were obtained. Heart rate, systolic BP, and RPP were significantly increased by Cardio tennis (p <= 0.05), though returned to pre-exercise levels after 30 minutes (p > 0.05). Heart rate and BP did not differ between groups pre- or 30-minute postexercise (p > 0.05); however, these were lower in younger males during and higher in younger females postsession (p <= 0.05). Lactate and glucose concentrations were increased in all groups (p <= 0.05), with lactate being highest in male groups (p <= 0.05), without differences in glucose between groups (p > 0.05). Stroke and step counts were not different between groups (p > 0.05). Ratings of perceived exertion and perceived challenge were lowest in the younger male group compared with all other groups (p <= 0.05). Cardio tennis presents as an effective stimulus to invoke sufficient cardiovascular and metabolic load to benefit health and fitness, though age- and sex-based responses should be considered in prescription.