LAUSR

CrossFit is a physically and metabolically-demanding training mode increasing in popularity among recreational athletes. Presently, however, scarce evidence is available documenting its energetic profile. This study investigated the metabolic characteristics of a CrossFit training bout as measured by expired gases and blood lactate. Eleven females and 7 males completed a 12-minute CrossFit bout on two occasions separated by three days. During both experimental sessions (Pt1, Pt2), subjects performed as many rounds as possible (AMRAP) within the timed workout which consisted of consisted of 12 box jumps (30” for males, 20” for females), 6 thrusters (24 kg for males, 16 kg for females), and 6 bar-facing burpees in sequence. Oxygen consumption (VO 2 ), respiratory exchange ratio (RER), blood lactate (BL), and repetitions completed were measured during both experimental sessions. The average VO 2 and RER of both bouts (Pt1 and Pt2) was 37.0 ± 4.8 ml/kg/min and 1.04 ± 0.1, respectively. Average BL significantly increased above pre-exercise concentrations (3.0 ± 1.3 mmol/L) at 4 min (10.1 ± 3.2 mmol/L; p < 0.01), 8 min (12.3 ± 3.5 mmol/L; p < 0.01), and immediately post at 12 min (12.6 ± 3.9 mmol/L; p < 0.01). Repetitions completed in Pt2 (140.2 ± 25.9) were significantly different to repetitions completed in Pt1 (131.2 ± 27.2) (p = 0.023). Average repetitions completed in Pt1 and Pt 2 was 135.7 ± 26.6. These data suggest that CrossFit is a metabolically-demanding conditioning method that relies heavily on both aerobic and anaerobic energy production and may represent an alternative to traditional methods of exercise to improve fitness and longevity.