Immediate Increase in the Root Mean Square of Successive Differences after Three Bouts of Remote Ischemic Preconditioning: A Randomized Controlled Trial

(1) Background: Remote ischemic preconditioning (RIPC) is an intervention involving the application of brief episodes of ischemia and reperfusion to distant tissues to activate protective pathways in the heart. There is evidence suggesting the involvement of the autonomic nervous system (ANS) in RIPC-induced cardioprotection. This study aimed to investigate the immediate effects of RIPC on the ANS using a randomized controlled trial. (2) Methods: From March 2018 to November 2018, we conducted a single-blinded randomized controlled study involving 51 healthy volunteers (29 female, 24.9 [23.8, 26.4] years). Participants were placed in a supine position and heart rate variability was measured over 260 consecutive beats before they were randomized into either the intervention or the SHAM group. The intervention group underwent an RIPC protocol (3 cycles of 5 min of 200 mmHg ischemia followed by 5 min reperfusion) at the upper thigh. The SHAM group followed the same protocol but on the right upper arm, with just 40 mmHg of pressure inflation, resulting in no ischemic stimulus. Heart rate variability measures were reassessed afterward. (3) Results: The intervention group showed a significant increase in RMSSD, the possible marker of the parasympathetic nervous system (IG: 14.5 [5.4, 27.5] ms vs. CG: 7.0 [-4.3, 23.1 ms], p = 0.027), as well as a significant improvement in Alpha 1 levels compared to the control group (IG: -0.1 [-0.2, 0.1] vs. CG: 0.0 [-0.1, 0.2], p = 0.001). (4) Conclusions: Our results hint that RIPC increases the RMSSD and Alpha 1 parameters showing possible immediate parasympathetic modulations. RIPC could be favorable in promoting cardioprotective or/and cardiovascular effects by ameliorating ANS modulations.

The Effect of Direct and Remote Postexercise Ischemic Conditioning on Muscle Soreness and Strength 24 Hours After Eccentric Drop Jumps

ABSTRACT

Lillquist, T, Mahoney, SJ, Kotarsky, C, McGrath, R, Jarajapu, Y, Scholten, SD, and Hackney, KJ. The effect of direct and remote postexercise ischemic conditioning on muscle soreness and strength 24 hours after eccentric drop jumps. J Strength Cond Res 37(9): 1870-1876, 2023-Strategic limb occlusion applied after exercise may facilitate recovery, not only in directly targeted tissue but also in remote areas of the body. The purpose of this study was to determine if postexercise ischemic conditioning (PEIC) applied directly to one leg facilitated recovery in the targeted leg and the contralateral leg that did not receive direct PEIC. Twenty active men participated in a single-blind, randomized, crossover design. Subjects completed 2 paired testing sessions (PEIC and control-SHAM) that included pre-assessments and 24-hour postassessments. Each paired testing session included an eccentric drop jump task, which has been shown to increase lower-body muscle soreness and decrease strength. After each drop jump task, occlusion cuffs were immediately applied. In the PEIC session, ∼198 mm Hg was applied directly to one leg (PEIC-Direct), whereas the contralateral leg received a nonphysiological stimuli of 20 mm Hg (PEIC-Remote). In the control-SHAM session, both legs directly and remotely received the 20 mm Hg pressure. Unilateral pre-assessments and 24-hour postassessments included muscle soreness using a visual analog scale and strength via peak torque assessment across the force-velocity spectrum (flexion/extension 60/60, 120/120, 180/180, 240/240, 300/300 °·s -1 ), and a maximal eccentric extension (30/30 °·s -1 ). Muscle soreness was significantly increased ( p < 0.05) at 24 hours compared with pretreatment except for PEIC-Direct (1.19 ± 0.78 vs. 2.32 ± 1.48, p = 0.096). Across the force-velocity spectrum, there were no significant differences observed between any associated pretest and posttest ( p > 0.05). PEIC applied directly to target leg after eccentric drop jumps attenuated perceived quadriceps muscle soreness 24 hours post; however, there was no effect on muscle strength.

Effects of Recurring IPC vs. rIPC Maneuvers on Exercise Performance, Pulse Wave Velocity, and Red Blood Cell Deformability: Special Consideration of Reflow Varieties

Beneficial effects of (remote) ischemia preconditioning ((r)IPC), short episodes of blood occlusion and reperfusion, are well-characterized, but there is no consensus regarding the effectiveness of (r)IPC on exercise performance. Additionally, direct comparisons of IPC and rIPC but also differences between reflow modes, low reflow (LR) and high reflow (HR) in particular, are lacking, which were thus the aims of this study. Thirty healthy males conducted a performance test before and after five consecutive days with either IPC or rIPC maneuvers (n = 15 per group). This procedure was repeated after a two-week wash-out phase to test for both reflow conditions in random order. Results revealed improved exercise parameters in the IPC LR and to a lesser extent in the rIPC LR intervention. RBC deformability increased during both rIPC LR and IPC LR, respectively. Pulse wave velocity (PWV) and blood pressures remained unaltered. In general, deformability and PWV positively correlated with performance parameters. In conclusion, occlusion of small areas seems insufficient to affect large remote muscle groups. The reflow condition might influence the effectiveness of the (r)IPC intervention, which might in part explain the inconsistent findings of previous investigations. Future studies should now focus on the underlying mechanisms to explain this finding.

Effect of 10 consecutive days of remote ischemic preconditioning on local neuromuscular performance

BACKGROUND

Most studies focus on the effects of a single remote ischemic preconditioning (RIPC) session on performance. However, the training-like effect of repeat RIPC sessions performed on consecutive days could potentially be even more beneficial to neuromuscular performance than a single RIPC session. Therefore, aim of the study was to assess the impact of 10 days of RIPC on local neuromuscular performance.

METHODS

Thirty-seven male participants performed 10 days of either RIPC or sham-controlled condition. Before and after procedure, the maximal voluntary contraction and muscle fatigue were assessed by dynamometry and surface electromyography (EMG) of the isometric extension of the knee joint. The following neuromuscular outcomes were investigated: peak torque (PKTQ); rate of force development (RTD); time to failure; and the slope of median frequency of power spectrum (MDF) and EMG amplitude.

RESULTS

After RIPC, while there was no change in PKTQ and time to failure, the late RTD and MDF slope were significantly affected. The RTD at 0-100 and 0-200 ms showed 24 and 16% increase, respectively, while the MDF slope showed 24% decrease in rectus femoris.

CONCLUSIONS

10 days of RIPC induced neuromuscular performance changes in the quadriceps muscle. Even though there were no changes in task to failure performance, RIPC showed EMG changes limited to rectus femoris and increased late RTD in MVC task.

Effect of Ischemic Preconditioning on Maximal Swimming Performance

ABSTRACT

Williams, N, Russell, M, Cook, CJ, and Kilduff, LP. Effect of ischemic preconditioning on maximal swimming performance. J Strength Cond Res 35(1): 221-226, 2021-The effect of ischemic preconditioning (IPC) on swimming performance was examined. Using a randomized, crossover design, national- and international-level swimmers (n = 20; 14 men, 6 women) participated in 3 trials (Con, IPC-2h, and IPC-24h). Lower-body IPC (4 × 5-minute bilateral blood flow restriction at 160-228 mm Hg and 5-minute reperfusion) was used 2 hours (IPC-2h) or 24 hours (IPC-24h) before a self-selected (100 m, n = 15; 200 m, n = 5) swimming time trial (TT). The Con trial used a sham intervention (15 mm Hg) 2 hours before exercise. All trials required a 40-minute standardized precompetition swimming warm-up (followed by 20-minute rest; replicating precompetition call room procedures) 1 hour before TT. Capillary blood (pH, blood gases, and lactate concentrations) was taken immediately before and after IPC, before TT and after TT. No effects on TT for 100 m (P = 0.995; IPC-2h: 64.94 ± 8.33 seconds; IPC-24h: 64.67 ± 8.50 seconds; Con: 64.94 ± 8.24 seconds), 200 m (P = 0.405; IPC-2h: 127.70 ± 10.66 seconds; IPC-24h: 129.26 ± 12.99 seconds; Con: 130.19 ± 10.27 seconds), or combined total time (IPC-2h: 84.27 ± 31.52 seconds; IPC-24h: 79.87 ± 29.72 seconds; Con: 80.55 ± 31.35 seconds) were observed after IPC. Base excess (IPC-2h: -13.37 ± 8.90 mmol·L-1; Con: -13.35 ± 7.07 mmol·L-1; IPC-24h: -16.53 ± 4.65 mmol·L-1), pH (0.22 ± 0.08; all conditions), bicarbonate (IPC-2h: -11.66 ± 3.52 mmol·L-1; Con: -11.62 ± 5.59 mmol·L-1; IPC-24h: -8.47 ± 9.02 mmol·L-1), total carbon dioxide (IPC-2h: -12.90 ± 3.92 mmol·L-1; Con: -11.55 ± 7.61 mmol·L-1; IPC-24h: 9.90 ± 8.40 mmol·L-1), percentage oxygen saturation (IPC-2h: -0.16 ± 1.86%; Con: +0.20 ± 1.93%; IPC-24h: +0.47 ± 2.10%), and blood lactate (IPC-2h: +12.87 ± 3.62 mmol·L-1; Con: +12.41 ± 4.02 mmol·L-1; IPC-24h: +13.27 ± 3.81 mmol·L-1) were influenced by swimming TT (P < 0.001), but not condition (all P > 0.05). No effect of IPC was seen when applied 2 or 24 hours before swimming TT on any indices of performance or physiological measures recorded.

Effect of Ischemic Preconditioning on Marathon-Induced Changes in Serum Exerkine Levels and Inflammation

Participation in a long-distance run, e.g., marathon or ultramarathon, continues to increase. One side effect of long-distance running is excessive inflammation manifested by the rise in inflammatory cytokine levels. We here aimed to elucidate the effects of 10-day ischemic preconditioning (IPC) training on marathon-induced inflammation and to evaluate the role of serum-stored iron in this process. The study involved 19 recreational runners taking part in a marathon. IPC training was performed in the course of four cycles, by inflating and deflating a blood pressure cuff at 5-min intervals (IPC group, n = 10); the control group underwent sham training (n = 9). The levels of inflammatory and others markers (FSTL-1, IL-6, IL-15, leptin, resistin, TIMP-1, OSM, and LIF) were measured before and 24 h after training; and before, immediately after, and 24 h and 7 day after the marathon. The 10-day IPC training increased serum leptin levels. IL-6, IL-10, FLST-1, and resistin levels were increased, while TIMP-1 levels were decreased in all runners after the marathon. The changes were significantly blunted in runners from the IPC group compared with the control group. Baseline serum iron levels correlated with IL-6 and FSTL-1 levels; serum ferritin correlated with IL-6, FSTL-1, and resistin levels after the marathon. Conversely, serum TIMP-1 levels inversely correlated with serum iron levels. Although not evident at baseline, IPC training significantly reduced marathon-induced inflammation. In addition, the reduced responsiveness and attenuation of running-induced inflammation were inversely related to baseline serum iron and ferritin levels.

Remote Ischemic Preconditioning Has No Short Term Effect on Blood Pressure, Heart Rate, and Arterial Stiffness in Healthy Young Adults

Objective

Remote ischemic preconditioning (RIPC) are short episodes of ischemia and reperfusion applied to remote tissue to trigger responses in a specific organ or cardiovascular bed. This study investigates whether RIPC has a short-term effect on blood pressure (BP), heart rate, and arterial stiffness.

Patients and Methods

From March 2018 to August 2018, we included 40 healthy volunteers (23 female, age 25.6 ± 2.8 years) into this single-blinded randomized-controlled crossover trial. After measuring BP, heart rate, and arterial stiffness in supine position participants were randomized into intervention or SHAM group. The intervention group then underwent a RIPC protocol (3 cycles of 5 min of 200 mmHg ischemia followed by 5 min reperfusion) at the thigh. The SHAM group followed the same protocol just on the upper arm with 40 mmHg pressure inflation. Directly after this 30-min procedure a reassessment of hemodynamic measures was conducted.

Results

There were no significant changes in all five outcome parameters when comparing the effect of RIPC to SHAM. In peripheral systolic BP the mean difference between groups was Δ1.14 ± 6.5 mmHg (p = 0.672), and for diastolic BP Δ−0.69 ± 4.5 mmHg (p = 0.507). Heart rate shoed a Δ−0.8 ± 4.7 beats/min (p = 0.397). Regarding arterial stiffness measures, there was also no significant improvements thru RIPC. The mean difference between RIPC and SHAM for central systolic BP was Δ0.40 ± 7.2 mmHg (p = 0.951) and for PWV Δ0.01 ± 0.26 m/s (p = 0.563).

Conclusion

This study could not find any short-term effects of RIPC on arterial stiffness, BP, and heart rate in a RCT in young healthy adults.

An overview of ischemic preconditioning in exercise performance: A systematic review

Ischemic preconditioning (IPC) is an attractive method for athletes owing to its potential to enhance exercise performance. However, the effectiveness of the IPC intervention in the field of sports science remains mitigated. The number of cycles of ischemia and reperfusion, as well as the duration of the cycle, varies from one study to another. Thus, the aim of this systematic review was to provide a comprehensive review examining the IPC literature in sports science. A systematic literature search was performed in PubMed (MEDLINE) (from 1946 to May 2018), Web of Science (sport sciences) (from 1945 to May 2018), and EMBASE (from 1974 to May 2018). We included all studies investigating the effects of IPC on exercise performance in human subjects. To assess scientific evidence for each study, this review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. The electronic database search generated 441 potential articles that were screened for eligibility. A total of 52 studies were identified as eligible and valid for this systematic review. The studies included were of high quality, with 48 of the 52 studies having a randomized, controlled trial design. Most studied showed that IPC intervention can be beneficial to exercise performance. However, IPC intervention seems to be more beneficial to healthy subjects who wish to enhance their performance in aerobic exercises than athletes. Thus, this systematic review highlights that a better knowledge of the mechanisms generated by the IPC intervention would make it possible to optimize the protocols according to the characteristics of the subjects with the aim of suggesting to the subjects the best possible experience of IPC intervention.

The effect of IPC on central and peripheral fatiguing mechanisms in humans following maximal single limb isokinetic exercise

Ischemic preconditioning (IPC) has been suggested to preserve neural drive during fatiguing dynamic exercise, however, it remains unclear as to whether this may be the consequence of IPC-enhanced muscle oxygenation. We hypothesized that the IPC-enhanced muscle oxygenation during a dynamic exercise task would subsequently attenuate exercise-induced reductions in voluntary activation. Ten resistance trained males completed three 3 min maximal all-out tests (AOTs) via 135 isokinetic leg extensions preceded by treatments of IPC (3 × 5 min bilateral leg occlusions at 220 mmHg), SHAM (3 × 5 min at 20 mmHg) or CON (30 min passive rest). Femoral nerve stimulation was utilized to assess voluntary activation and potentiated twitch torque during maximal voluntary contractions (MVCs) performed at baseline (BL), prior to the AOT (Pre), and then 10 sec post (Post). Tissue oxygenation (via near-infrared spectroscopy) and sEMG activity was measured throughout the AOT. MVC and twitch torque levels declined (MVC: -87 ± 23 Nm, 95% CI = -67 to -107 Nm; P < 0.001, twitch: -30 ± 13 Nm; 95% CI = -25 to -35 Nm; P < 0.001) between Pre and Post without reductions in voluntary activation (P = 0.72); there were no differences between conditions (MVC: P = 0.75, twitch: P = 0.55). There were no differences in tissue saturation index (P = 0.27), deoxyhemoglobin concentrations (P = 0.86) or sEMG activity (P = 0.92) throughout the AOT. These findings demonstrate that IPC does not preserve neural drive during an all-out 3 min isokinetic leg extension task.

Effect of long-term remote ischemic conditioning in patients with chronic ischemic heart failure

Remote ischemic conditioning (RIC) protects against acute ischemia-reperfusion injury and may also have beneficial effects in patients with stable cardiovascular disease. We investigated the effect of long-term RIC treatment in patients with chronic ischaemic heart failure (CIHF). In a parallel group study, 22 patients with compensated CIHF and 21 matched control subjects without heart failure or ischemic heart disease were evaluated by cardiac magnetic resonance imaging, cardiopulmonary exercise testing, skeletal muscle function testing, blood pressure measurement and blood sampling before and after 28 ± 4 days of once daily RIC treatment. RIC was conducted as four cycles of 5 min upper arm ischemia followed by 5 min of reperfusion. RIC did not affect left ventricular ejection fraction (LVEF) or global longitudinal strain (GLS) in patients with CIHF (p = 0.63 and p = 0.11) or matched controls (p = 0.32 and p = 0.20). RIC improved GLS in the subgroup of patients with CIHF and with NT-proBNP plasma levels above the geometric mean of 372 ng/l (p = 0.04). RIC did not affect peak workload or oxygen uptake in either patients with CIHF (p = 0.26 and p = 0.59) or matched controls (p = 0.61 and p = 0.10). However, RIC improved skeletal muscle power in both groups (p = 0.02 for both). In patients with CIHF, RIC lowered systolic blood pressure (p < 0.01) and reduced NT-proBNP plasma levels (p = 0.02). Our findings suggest that long-term RIC treatment does not improve LVEF but increases skeletal muscle function and reduces blood pressure and NT-proBNP in patients with compensated CIHF. This should be investigated in a randomized sham-controlled trial.