CrossFit has grown in popularity over the past few years, which has led to an increased need for more research on this type of training. The purpose of this study was to assess the effect of CrossFit on aerobic capacity, anaerobic capacity (VO2max), power, performance, resting heart rate, resting blood pressure, and body composition. This study also assessed the rating of perceived exertion after a CrossFit workout and perceived recovery the day following a workout. The study was a pre-post design in which twelve participants completed a 30-day, 6-week, CrossFit training program. Prior to the exercise program, VO2max, maximal accumulated oxygen deficit, vertical jump height, body weight, body composition, resting heart rate, and resting blood pressure were assessed for each individual. The first three workouts of the 6-week program were also used to assess performance in three CrossFit workouts that stressed all three energy systems. These same measurements were assessed at the end of the 6-week training session. Paired-samples T-tests showed statistically significant improvement for VO2max (11%, p = .001), maximal accumulated oxygen deficit (25%, p = .021), performance in all three CrossFit workouts (CrossFit Total: 11%, p < .001; 500m row: 4%, p = .017; Fight Gone Bad: 31%, p < .001), and diastolic blood pressure (14%, p = .014). Average rating of perceived exertion for each training session was found to be 15 ± 2, and the average rating of perceived recovery was stated to be 7.2 ± 1.3. These results show that participating in a CrossFit training program based on the Training Guide can lead to improvements in aerobic capacity, anaerobic capacity, and performance using all three energy systems.