In this episode of the Critical Oxygen Podcast, coach Aaron Geiser and I discuss physiological testing. Physiological testing is beneficial for both health and wellness and sport performance. It provides guidance for training intensities and helps track adaptations. The benefits include individualized intensity zones, understanding performance improvements, and optimizing training efficiency. Physiological testing gives coaches credibility and allows for better communication with athletes. It also helps in designing race pace efforts and provides information on substrate utilization. Testing should be done with specific consistent protocols and be repeated over time to track changes. Testing can help individuals set goals, measure progress, and make adjustments to training and nutrition plans. It is a valuable tool for anyone looking to improve their fitness and health.