Dose of remote limb ischemic conditioning for enhancing learning in healthy young adults
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Remote limb ischemic conditioning (RLIC) is a technique in which tissues distant from the target organ are exposed to brief, sub-lethal bouts of ischemia. The effects of remotely applied ischemic conditioning are systemically transferred to the target organ, and typically manifested as protection from subsequent ischemic injury. Previous studies in our lab have found and confirmed that RLIC enhances learning and retention during motor training on a balance task. The current study tested the effect of RLIC dose (number of cycles) on learning enhancement in young, healthy adults. Forty healthy participants age 18–40 years were randomized to receive 5 cycles of sham conditioning (n = 9), 3 cycles of RLIC (n = 11), 4 cycles of RLIC (n = 10), or 5 cycles of RLIC (n = 10) using a blood pressure cuff around the upper arm once a day for 7 consecutive weekdays (Days 1–7). Participants concurrently trained on a balance task, bimanual cup stacking task, and a discrete sequence production task on Days 3–7. Change in performance on each of the three tasks was compared across groups. Participants in all four groups improved their performance on each of the three tasks over time. However, RLIC at any dose did not enhance learning on any of the three tasks. While RLIC is safe, inexpensive, and clinically feasible, reproducibility may be challenged by unidentified factors, raising critical challenges to the straightforward translation of RLIC for improving rehabilitation outcomes in individuals recovering from neurological injury.
KeywordsIschemic conditioning Motor learning Psychomotor performance
The authors would like to thank Nathan Baune, Allyson Getty, Gina Malito, Ali McGee, Allison Tsui, Kim Waddell, and Shelby Wilson for their assistance with data collection and the study participants for generously giving their time.
This study was funded by the National Institutes of Health (Grant number: R01 HD085930).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All the procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
Informed consent was obtained from all individual participants included in the study.
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