The effects of ischemia during rest intervals on strength endurance performance

PLOS ONE RESEARCH ARTICLE The effects of ischemia during rest intervals on strength endurance performance Robert Trybulski1,2☯, Marta Bichowska3☯, Rafal Piwowar4☯, Anna Pisz5☯, Michal Krzysztofik6☯, Aleksandra Filip-Stachnik6☯, Krzysztof Fostiak3☯, Piotr Makar ID3☯, Michal Wilk ID5,6☯* 1 Provita Zory Medical Center, Zory, Poland, 2 Department of Medical Sciences, The Wojciech Korfanty School of Economics, Katowice, Poland, 3 The Academy of Physical Education and Sport in Gdansk, Gdansk, Poland, 4 Health Fit, Zory, Poland, 5 Faculty of Physical Education and Sport, Charles University, Prague, Czech Republic, 6 Institute of Sport Sciences, Jerzy Kukuczka Academy of Physical Education in Katowice, Katowice, Poland a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 ☯ These authors contributed equally to this work. * Abstract OPEN ACCESS Citation: Trybulski R, Bichowska M, Piwowar R, Pisz A, Krzysztofik M, Filip-Stachnik A, et al. (2023) The effects of ischemia during rest intervals on strength endurance performance. PLoS ONE 18(4): e0280231. https://doi.org/10.1371/journal. pone.0280231 Editor: Daniel Boullosa, Universidade Federal de Mato Grosso do Sul, BRAZIL Received: November 16, 2021 Accepted: December 24, 2022 Published: April 6, 2023 Peer Review History: PLOS recognizes the benefits of transparency in the peer review process; therefore, we enable the publication of all of the content of peer review and author responses alongside final, published articles. The editorial history of this article is available here: https://doi.org/10.1371/journal.pone.0280231 Copyright: © 2023 Trybulski et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: All relevant data are within the manuscript and its Supporting information files. Background The study aimed to evaluate the effects of ischemia used during the rest periods between successive sets on maximal number of performed repetitions, time under tension and bar velocity during the bench press exercise. Methods and materials Thirteen healthy resistance trained men volunteered for the study (age = 28.5 ± 7.1 years; body mass = 87.2 ± 8.6 kg; bench press 1RM = 143.1 ± 20.7 kg; training experience = 11.0 ± 6.9 years). In experimental protocol the subjects performed 5 sets of bench press exercise at 70%1RM with maximal number of repetitions in each and with 5 minutes rest periods between each set. During the ischemia condition occlusion with 80% arterial occlusion pressure (AOP) was applied using a 10 cm wide cuff, before the first set of the bench press exercise and during all rest periods between sets (for 4.5 minute). During the control condition no ischemia was applied. Results The two-way repeated measures ANOVA showed a statistically significant interaction effect for time under tension (p = 0.022; η2 = 0.20). However, the results did not show a statistically significant interaction effect for peak bar velocity (p = 0.28; η2 = 0.10) mean bar velocity (p = 0.38; η2 = 0.08), and for number of performed repetitions (p = 0.28; η2 = 0.09). The post hoc analysis for interaction showed significantly shorter time under tension for ischemia condition compared to control in set 1 (p < 0.01). The post hoc analysis for main effect of condition revealed that time under tension was significantly shorter for ischemia compared to control condition (p = 0.04). PLOS ONE | https://doi.org/10.1371/journal.pone.0280231 April 6, 2023 1/9 PLOS ONE Funding: The study was supported by the statutory research of the Jerzy Kukuczka Academy of Physical Education in Katowice, Poland. The study was also funded by the Grant Agency of Charles University through a grant awarded to MK and MW (PRIMUS/22/HUM/019). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Effects of ischemia on strength endurance Conclusion The results of this study indicate that ischemia intra-conditioning does not increase strength-endurance performance as well as bar velocity during bench press exercise performed to muscle failure. Competing interests: The authors have declared that no competing interests exist. Introduction Ischemia is a method of restricting blood flow through the special cuffs which can be used in the limbs and can be applied during the rest as well during the different types of physical activity [1]. So far, much attention has been devoted to the use of ischemia during resistance exercise. Ischemia induced before or during effort increase exercise physical performance as well as stimulates physiological responses such as improvement of metabolic efficiency (attenuating ATP depletion), also glycogen depletion and the lactate production [2–11]. Further ischemia causes changes in systemic VO2, in the deoxygenation of muscular Hb/Mb, and the opening of the ATP-dependent K+ channels which can enhance the level of performance [3–5,8,9,12]. There are many different methods related to the point, timing of application and the duration of ischemia as part of physical exercise: pre-conditioning (ischemia induced only before a training session), continuous (ischemia induced during the exercise and rest periods), and intermittent (ischemia induced during exercise, not during rest periods) [13–15] The main differences between those methods are related to the point when ischemia is induced [16]. Recently, another method of using ischemia as part of resistance exercises has been introduced called ischemic intra-conditioning [14]. During ischemic intra-conditioning, the cuffs are applied only during each rest period between sets of resistance exercise and released before start effort [14]. Wilk et al. [14] showed an increase in bar velocity and power output during the bench press exercise (5 sets, 3 repetitions, 60%1RM; 5-minute rest periods) when ischemia (80% full arterial occlusion pressure (AOP) of the upper limb at rest) was applied before each set of resistance exercise. Since the ischemia used only during the rest periods increase explosive performance [17] it is possible that the positive effect may also apply to maximal strength as well as strength-endurance performance. Previous study showed that ischemic pre-conditioning increases maximal number of performed repetitions during resistance exercise for the lower and upper limbs [16,18–20]. Novaes et al. [20] showed that ischemic pre-conditioning applied 40 min before warm-up (4 cycles of 5-minute ischemia at 220mmHg) and completed 5 min before warm-up increased total training volume (sum of a total number of performed repetitions x load in bench press, leg press, lateral pulldown, hack machine squat, shoulder press, and Smith back squat) compared to control condition. Similar Marocolo et al. [19] showed that (...truncated)