Ischemic Preconditioning Improves Maximal Accumulated Oxygen Uptake and Time to Exhaustion in NCAA Division I Middle‐Distance Runners

Purpose Ischemic preconditioning prevents reduction in blood flow after strenuous endurance exercise, and has been shown to improve swimming, cycling and running time trial performance, particularly at vigorous exercise intensities. However, not all studies have corroborated these findings. In addition, data supporting the role of ischemic preconditioning to improve supramaximal exercise is limited, particularly in competitive elite trained athletes seeking a performance advantage. The aim of the present study was to test the hypothesis that ischemic preconditioning improves supramaximal accumulated oxygen uptake and time to exhaustion in NCAA Division I middle‐distance runners. Methods A randomized sham‐controlled crossover study was employed in which 10 NCAA Division I middle‐distance (800 to 1600 meter) track athletes (age: 21±1 yr; VO 2 max: 65±7 mlO 2 ·kg· − 1 ·min − 1 ) completed three supramaximal (110% VO 2 max) treadmill running protocols to volitional exhaustion coupled with indirect calorimetry to assess maximal accumulated oxygen uptake at baseline, after a sham control trial (mock preconditioning), and with limb‐based ischemic preconditioning (4×5 min cycles of brachial artery ischemia/reperfusion). Accumulated oxygen demand (mlO 2 ·kg − 1 ), the primary outcome variable, was calculated by multiplying VO 2 (mlO 2 ·kg· − 1 ·min − 1 ) by duration (min) of the respective supramaximal run. Total treadmill work (kg·m) was determined by multiplying body mass (kg) × velocity (m·min − 1 ) × %grade × time (min). Experiments were conducted in accordance with the Declaration of Helsinki for protection of human subjects. Statistical Analysis A three‐way repeated‐measures ANOVA with adjustment for multiple comparisons was used for within‐group differences (i.e., baseline vs sham vs ischemic preconditioning) in maximal accumulated oxygen uptake. Results Ischemic preconditioning (122±38 sec) increased (P=0.0001) time to exhaustion by 22% compared with both baseline (99±23 sec, 95% CI: 4.8–40.6, P=0.014) and sham (101±30 sec, 95% CI: 6.7–34.2, P=0.001). Effect size for these trial differences as estimated by the Partial Eta 2 (0.58) were large. As a result, the maximal accumulated oxygen demand was considerably greater (P=0.001) with ischemic preconditioning. During their supramaximal run in the presence of ischemic preconditioning, athletes accumulated 132±40 mlO 2 ·kg − 1 , a substantial (Partial Eta 2 = 0.64) increase compared with baseline (106±28 mlO 2 ·kg − 1 , P=0.006, 95% CI:7.9–42.6) and sham (110±34 mlO 2 ·kg − 1 , P=0.007. 95% CI: 6.6–36.5). Likewise, total treadmill work also significantly (P=0.002) increased (from baseline: 1908±204 kg·m to 2331±303 kg·m with ischemic preconditioning). There were no statistical differences in time to exhaustion, maximal accumulated oxygen demand, or treadmill work between baseline and sham. Conclusions Limb‐based ischemic preconditioning considerably improves anaerobic treadmill time to exhaustion and accumulated oxygen uptake in NCAA Division I middle‐distance track athletes. Additional work is needed to confirm whether these laboratory‐based performance benefits can be translated to better outcomes in real competitive track meets. Support or Funding Information We thank the Department of Health and Nutritional Sciences for the equipment and supplies to conduct the study. This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .