High-Impact Cardio Damages Blood Cells

The phenomenon, known as "footstrike hemolysis," has been recognized since as early as 1881 when a German soldier experienced red blood cell destruction after prolonged marching. It is caused by the mechanical trauma of red blood cells being compressed in the small capillaries of the feet during repetitive impact. A recent study published in the journal *Blood Red Cells & Iron* examined ultrarunners and found that extreme endurance running accelerates the aging and breakdown of red blood cells. Researchers observed that after races of 40km (about 25 miles) and 171km (about 106 miles), the athletes' red blood cells became less flexible, potentially hindering their ability to transport oxygen efficiently. The damage to red blood cells appears to increase with the length of the run. The study noted that while signs of damage were present after a 40km race, they were significantly amplified in athletes who completed the 171km ultramarathon. For most people, this red blood cell destruction is mild and doesn't lead to anemia or iron deficiency. However, in endurance athletes, particularly long-distance runners, it can contribute to a condition sometimes called "sports anemia." Symptoms can include fatigue, weakness, dizziness, and reduced exercise performance. Factors that can increase the risk of footstrike hemolysis include running on hard surfaces and using worn-out running shoes that have lost their cushioning. Elite athletes and those who rapidly increase their training volume may also be at higher risk. Preventive measures focus on reducing the impact on the feet. This includes choosing well-cushioned footwear, running on softer surfaces like trails or tracks, and incorporating low-impact cross-training activities such as swimming or cycling.