Ischemic Preconditioning: Improved Cycling Performance Despite Nocebo Expectation

Abstract

Purpose: Ischemic preconditioning (IPC) through purposeful circulatory occlusion may enhance exercise performance. The value of IPC for improving performance is controversial owing to challenges with employing effective placebo controls. This study examines the efficacy of IPC versus a deceptive sham protocol for improving performance to determine whether benefits of IPC are attributable to true physiological effects. It was hypothesized that IPC would favorably alter performance more than a sham treatment and that physiological responses to exercise would be affected only after IPC treatment. Methods: In a randomized order, 16 participants performed incremental exercise to exhaustion on a cycle ergometer in control conditions and after sham and IPC treatments. Participants rated their belief as to the efficacy of each treatment compared with control. Results: Time to exhaustion was greatest after IPC (control = 1331 [270] s, IPC = 1429 [300] s, sham = 1343 [255] s, P = .02), despite negative performance expectations after IPC and positive expectation after sham. Maximal aerobic power remained unchanged after both SHAM and IPC (control = 42.0 [5.2], IPC = 41.7 [5.5], sham = 41.6 [5.5] mL·kg−1·min−1, P = .7), as did submaximal lactate concentration (control = 8.9 [2.6], sham = 8.0 [1.9], IPC = 7.7 [2.1] mmol, P = .1) and oxygen uptake (control = 37.8 [4.8], sham = 37.5 [5.3], IPC = 37.5 [5.5] mL·kg−1·min−1, P = .6). Conclusions: IPC before cycling exercise provides an ergogenic benefit that is not attributable to a placebo effect from positive expectation and that was not explained by traditionally suggested mechanisms.

Local and Remote Ischemic Preconditioning Improves Sprint Interval Exercise Performance in Team Sport Athletes

“…One limitation of this study was that participants were not completely blinded during the study. The presence of the placebo effect in IPC experiments remains controversial, with some studies finding [34,35] and others not findings evidence for this [7,36]. The use of placebo is a standard control component of most clinical trials, and it attempts to clarify the potential effect of treatment.…”

“…The results indicated that SHAM induced similar levels of discomfort to IPC but comparable exercise performance outcomes to the CON [7]. In the study of Cheung et al [36], they informed participants that the effects of IPC and SHAM on exercise performance were unclear before starting the study, and used the therapeutic ultrasound procedure as SHAM condition. They reported that 69% of participants believed that IPC would hinder exercise performance, whereas SHAM ultrasound could improve performance [36].…”

“…In the study of Cheung et al [36], they informed participants that the effects of IPC and SHAM on exercise performance were unclear before starting the study, and used the therapeutic ultrasound procedure as SHAM condition. They reported that 69% of participants believed that IPC would hinder exercise performance, whereas SHAM ultrasound could improve performance [36]. Nevertheless, the results indicated that only IPC could significantly increase time to exhaustion during incremental cycling test [36].…”

Methodological Variations Contributing to Heterogenous Ergogenic Responses to Ischemic Preconditioning

“…Despite 73% of participants expecting their performance to improve following the sham condition, only IPC improved swimming performance relative to the control. Similarly, Cheung et al (2020) reported improved cycling time-to-exhaustion following IPC despite participants reporting negative performance expectations after IPC and positive performance expectations after their sham.…”

Blood Flow Restriction: Cause for Optimism, But Let’s Not Abandon The Fundamentals

“…It is not recommended that BFR be used prior to explosive activities due to BFR exercises being performed at or near volitional fatigue. While it is early to make any definitive conclusions, there is some early evidence that ischemic preconditioning may enhance recovery after athletic performance, [45][46][47][48][49] but evidence to the contrary exists as well. 50,51 While BFR appears to be a very promising and exciting innovation in our field, it is important to keep in mind that accepted, proven training practices and principles are not abandoned.…”