Fit enough for Hyrox or a marathon? Why that doesn’t necessarily mean your heart is ready

Training performance and VO2 max may not fully reveal your heart health status, especially for high-intensity events like Hyrox or marathons. To be cautious, an ECG or other heart screenings might be recommended. Turning 40 can make people consider new activities, such as participating in Hyrox races. However, even those with marathon experience may underestimate the necessity of proper preparation.

A Thailand-based fitness coach, Leroy Saunders, died during the BYD Hyrox Bangkok 2026 event on Aug 13, raising concerns about heart health and race safety. Saunders had participated in previous Hyrox events and owned a CrossFit gym in Bangkok. Despite the risk of cardiac events during endurance activities, not all events pose the same danger.

Both marathons and Hyrox combine intense bursts of exercise with strength movements, causing rapid heart rate and blood pressure spikes. The risk depends on an individual's fitness level, medical conditions, and training preparation. Many heart conditions remain undetected until stressed by intense exercise. For older participants, coronary artery disease is the leading cause, while inflammation of the heart muscle or severe heart valve disease are less common.

A VO2 max test measures how well your body uses oxygen during exercise. It involves wearing a mask connected to a metabolic analyser while exercising on a treadmill or bike. The highest oxygen uptake achieved during the test is recorded as VO2 max in ml/kg/min. A VO2 max of 35 to 45ml/kg/min is considered average for adult men. If you haven't been exercising regularly or are preparing for a rigorous event like Hyrox, consulting with a healthcare professional before starting a new training program is advisable.