Foot impact force and intravascular hemolysis during distance running.
Level 2 - randomized trial
Randomized crossover trial in humans
PubMed 3366521 · doi:10.1055/s-2007-1024979
What was done
Fourteen trained male distance runners (VO2 max 66.1 ± 5.0 ml·kg⁻¹·min⁻¹) completed two treadmill running sessions and one resting control trial in randomized order, separated by 7 days. Treadmill runs were performed at 215 m·min⁻¹ for 10,000 footstrikes at either +6% (uphill) or -6% (downhill) grade. Blood samples were drawn 15 minutes before, immediately before, and immediately, 1 hour, and 2 hours after exercise to measure hemoglobin, hematocrit, plasma free hemoglobin, and haptoglobin.
What was found
Mean foot impact force was 11% higher during downhill compared to uphill running. Following treadmill running, haptoglobin decreased and plasma free hemoglobin increased significantly (P < 0.05). These alterations in hemolysis markers were significantly greater after downhill running compared to uphill running (P < 0.05). Specific absolute concentrations of blood markers were not reported in the abstract.
Why it matters
This study provides direct experimental evidence that higher mechanical footstrike impact forces exacerbate intravascular red blood cell destruction during running.
Limits
The sample was small (n = 14) and restricted to trained male runners, limiting generalizability to females, untrained individuals, or road surfaces. Exact numerical values and effect sizes for the blood markers were omitted from the abstract.
Cited by
- supports Running and physical impact in combat sports physically break red blood cells in the feet and body through footstrike hemolysis, releasing iron and contributing to iron loss in athletes.