Part 2: IPC in the Elite Athlete
Recently, the use of brief bouts of ischemia and reperfusion, often called Ischemic PreConditioning (IPC), has garnered a lot of interest amongst sports medicine practitioners and researchers alike as a method to augment performance. Briefly, IPC offers two distinct benefits across two separate time frames. The first window offers the potential for performance enhancement and occurs immediately following the application of IPC and lasts approximately four hours. The second window occurs approximately 24 hours following the intervention and extends through 72hrs post intervention. This window has mostly been shown to impact recovery following an intense bout of exercise.
Windows of Action for IPC
- 0 – 4 hours: increased performance measured via VO2max, fatiguing exercise, etc
- 24 – 72 hours: improved recovery from exercise via attenuation of muscle damage
The majority of the research exploring the first window, or the ergogenic benefits of IPC, has focused on various performance measures immediately after the intervention out to approximately forty-five minutes post. The main drivers producing an ergogenic aid during this period consist of increased tissue perfusion and maintaining aerobic respiration for a prolonged period of time. Collectively, these help to reduce muscle fatigue allowing for an acute spike in workload. Considering these mechanisms, IPC has had varying degrees of effectiveness depending on the energy system utilized during the task. For instance, when moderately trained runners performed IPC approximately forty-five minutes prior to a 5K time trial, they completed the time trial 34 seconds faster compared to the sham condition.(1) Interestingly, the authors also showed a significantly lower level of lactate when IPC was performed; an indication of improved aerobic respiration. Ischemic PreConditioning has also been shown to have a positive impact during anaerobic activities. Paradis-Deschenes and colleagues had resistance trained individuals perform five sets of five reps of maximal isokinetic knee extensions at 20 degrees/second preceded by IPC or sham IPC.(2) When the knee extensions were preceded by IPC, there was approximately a 12% greater increase in knee extensor strength compared to the sham condition. Despite the exercise task being anaerobic, mechanistically the increase in strength noted could also have been due to improvements in the delivery of nutrients via blood flow as the authors noted a 46% increase in perfusion of the quads at baseline; that increase remained 25% greater than the control following the fifth set. The effects of the first window of IPC on sprinting or other power activities have yielded trivial results, potentially due to those activities relying on the phosphocreatine system for energy.
The most common method of application amongst professional athletes targets the second window for recovery. Recently, Franz and colleagues showed that when IPC preceded a bout of eccentric exercise, there was a significant attenuation in creatine kinase release by approximately 95% compared to doing the same volume of eccentric exercise without IPC . Additionally, the IPC group had approximately 80% less pain compared to the group who only performed eccentrics.(3) Providing further support for IPC as a recovery modality, Page and colleagues showed when three cycles of IPC were performed following 100 depth jumps from a .5 meter box, knee extensor MVC returned to baseline at 72hrs post training while the sham group still had a 10% deficit.(4)
Although the above results are impressive, it should not go without mentioning the mixed results and limitations with IPC. For instance, when Jean St Michel and colleagues had elite swimmers perform four bouts of IPC prior to a 100m sprint, the average swim time decreased by 0.7 seconds. This appears to be largely impacted by three swimmers improving by 2.5-3.5 seconds. However, not everyone demonstrated an improvement. Three of the swimmers actually swam slower.(5) These results tell us a couple important things about IPC. First, on average, it looks like IPC can have a significant albeit small improvement in performance (effect size: .43). (6) When looking at the highest level athletes, this small improvement could separate first from second, or being on the medal stage versus not.
A second potential explanation for the mixed results includes the lack of use of an individualized pressure. This makes it particularly difficult to know how to optimize the application and why the dosage looks effective for some and not others. To our knowledge only one paper has used a personalized pressure with IPC.(7) They utilized 100% limb occlusion pressure (LOP) and it elicited a significant improvement in performance on the bike compared with a sham or control condition. Josh Slysz, PhD also highlighted the non-responder phenomena in his thesis and went on to state “…an amplified metabolic stimulus may be beneficial for those who do not respond to traditional IPC.”(8) This may further support the need for personalized pressures with IPC and also suggests the possibility that a number of enhancements observed with IPC are accomplished with the application of BFR and exercise.
Although the majority of IPC research on improving performance has focused on the effects occurring in the first window, there are a couple points to consider. The benefits during this window are time sensitive, with the bulk of research initiating the sport task immediately after the intervention. Although the benefit lasts approximately four hours post intervention, we do not know if there is a sustained ergogenic effect over the duration of the four hours or if the potential benefit gradually returns to baseline. Considering this, it could be challenging to implement this intervention in the context of a team sport since the window of benefits would likely exceed the duration of a team sport scenario. Therefore, use of IPC prior to performance might make the most sense in the context of track and field, swimming, and cycling.
However, when looking at this from a performance perspective, the responder / non-responder phenomenon must be factored into the decision to use IPC or not. We need to know how the individual athlete we are working with will respond. It appears some athletes will be extreme responders while a small percentage will either be a non responder or IPC could negatively affect them. These responses are best teased out prior to use for competition. For example, IPC could be implemented a week or two ahead of time as part of a training spike and then the response to the stimuli would be known.
Due to previously mentioned limitations with team sport events, IPC could be targeted for the potential benefit to improve recovery. When used in this manner, IPC is most commonly applied for three cycles of five minutes of ischemia/reperfusion either prior to the event or shortly after. If the athlete is able to implement IPC within four hours of the event, there may be potential to improve the subsequent performance along with improving their recovery following the event.
2. Paradis-Deschênes P, Joanisse DR, Billaut F. Ischemic preconditioning increases muscle perfusion, oxygen uptake, and force in strength-trained athletes. Appl Physiol Nutr Metab. 2016;41(9):938-944.
4. Page W, Swan R, Patterson SD. The effect of intermittent lower limb occlusion on recovery following exercise-induced muscle damage: A randomized controlled trial. J Sci Med Sport. 2017;20(8):729-733.
6. Salvador AF, De Aguiar RA, Lisbôa FD, Pereira KL, Cruz RS, Caputo F. Ischemic Preconditioning and Exercise Performance: A Systematic Review and Meta-Analysis. Int J Sports Physiol Perform. 2016;11(1):4-14.
8. Slysz J. Optimizing the Ergogenic Use of Ischemic Preconditioning. Published online 2019.https://atrium2.lib.uoguelph.ca/xmlui/bitstream/handle/10214/17397/Slysz_Joshua_201909_PhD.pdf?sequence=3&isAllowed=y