Five repeated maximal efforts of apneas increase the time to exhaustion in subsequent high-intensity exercise
Graphical abstract
Introduction
In humans, intermittent static apneas or breath holds (BH) with face immersion in cold water (BHFI) cause dynamic contractions of the spleen (Baković et al., 2003), leading to a noticeable release of red cells to the blood (RBC), amounting to almost 10 % of total systemic blood volume. Similarly, hemoconcentration is enhanced and hematocrit (Hct) is increased by 9.5 % in professional Korean ama during diving (Baković et al., 2005; Hurford et al., 1990). Concurrently, spleen size is reduced by 19.5 % (Hurford et al., 1990), while the total circulatory volume of RBC increases by 4.9 % and 1.7 % in divers and untrained divers, respectively, after five repeated BHFI at 2-minute intervals (Baković et al., 2005). It appears that repeated BH with small intervals between is enough to cause optimal contraction of the spleen, allowing for the release of significant amounts of circulating RBC in both experienced and untrained divers (Baković et al., 2006, 2005, 2003; Hurford et al., 1990). The expulsion of RBC from the spleen, however, may not necessarily lead to a measurable change in concentration of dependent blood variables such as hemoglobin (Hb) or Hct, especially in arterialized taken blood. On the other hand, RBC from the spleen, very likely leads to a increase in circulating blood volume which in turn may favor oxygen transport, O₂ consumption enhancement and hence may assists O₂ deficiency reduction (Di Prampero and Ferretti, 1999; Rossiter, 2011) and improves aerobic capacity in exercise (Vatner et al., 1974). It is also well accepted that raising, by transfusion, the number of circulating RBC boosts the oxygen-carrying capacity of the blood and improves performance (Ekblom et al., 1972). Therefore, it is reasonable to assume that acute intermittent static BH executed prior to exercise may enhance performance by improving blood oxygen-carrying capacity.
In addition, repeated BH with short intervals in between efforts causes, besides hematological alterations, a temporary retention of CO₂ (Baković et al., 2006), which may favor the unloading of oxygen from hemoglobin (the Bohr effect). Because of its well-documented vasodilatory action, the elevated levels of CO₂ (Gerbino et al., 1996) should also facilitate blood provision and hence efficient delivery of O₂ to exercising muscles. Whereas holding the breath leads to hypercapnia, the subsequent recovery is initially characterized by increased blood bicarbonate levels. For instance, after five repeated BHFI efforts (12 °C) with 2-minute intermediate intervals blood bicarbonate levels were elevated by 9.7 %, 7.9 %, and 5.4 %, respectively, in BH trained, intact subjects without diving experience and splenectomized subjects (Baković et al., 2005). Elite breath-hold divers, after static or dynamic BH, also show reduced blood lactic acid concentration and oxidative stress compared to a control group (Joulia et al., 2002). In other words, holding the breath induces acute hematological changes, which may facilitating oxygen delivery to active tissues. In summary, it is reasonable to assume, that intermittent static BHFI executed prior to exercise may enhance performance by enhanced aerobic metabolism.
Following the logic of boosting the oxygen-carrying capacity of the blood, two studies examined the acute effects of intermittent static breath holds (3 and 4 x BH) on subsequent exercise performance lasting over 4.5 min (4 km time trial cycling and 400 m freestyle swim respectively (Robertson et al., 2018; Sperlich et al., 2015)). Compared to the control condition in both studies, no rises in Hct, Hb, or blood lactate were observed and performance was not improved after the execution of dry static BH (Robertson et al., 2018; Sperlich et al., 2015). However, to our knowledge no study has been conducted to investigate the association between the acute effects of intermittent static breath holds and face immersion in cold water on subsequent high-intensity exercise capacity tests with a shorter duration than the aforementioned performance protocols.
Taken collectively, intermittent static maximal BH lead to powerful stress-inducing multifarious adaptations aiming at the survival of the body. Although divergent results exist, the oxygen-carrying capacity appears to remain elevated upon breath hold cessation; consequently, it was assumed that ensuing high-intensity performance would be enhanced. Therefore, the main purpose of this study was to examine whether intermittent static breath holds, with face immersion, executed prior to high-intensity exercise of short duration until exhaustion, can improve performance in healthy men.
Section snippets
Materials and methods
Ethical approval for this study was granted by the university ethics committee. Inclusion criteria were: age 18–30 years, male sex, at least moderate physical activity, good general health, freedom from any kind of medication, and unfamiliarity with any kind of breath-holding activities; exclusion criteria were: smoking or use of any kind of nicotine products, splenectomy, and blood donation or living at altitude in the three months prior to the study. On the basis of the inclusion‒exclusion
Results
Subjects performed five BHFI efforts and had an average BHT equal to 107.8 ± 32.6 s (98.5–117.1) and 144.2 ± 46.7 s (130.9–157.5) in the PRE, and POST BH training conditions, respectively. The mean maximum breath hold time for each repeated BHFI was significantly higher in the POST than in the PRE condition (P ≤ 0.05; Fig. 1).
Cycling time to exhaustion significantly increased (F(1.087, 9.785) = 9.917, P = 0.010) after five repeated BHFI efforts without being affected by BH training
Discussion
Over the last 2000 years, breath holding has been performed as part of fishing activities, sponge and pearl harvesting, as well in military endeavors (Ferretti, 2001). Nowadays, breath-holding activities are also involved in recreational diving, synchronized swimming, and free or technical diving athletics (Hurford et al., 1990). Moreover, the experimental protocol of five repeated static BHFI with 2-minute intervals between efforts has been widely used in apnea research, but not as a tool to
Ethics statement
Ethical approval was obtained by the National and Kapodistrian University of Athens, School of Physical Education and Sport Science, Internal Committee on Research Ethics – Bioethics.
Funding
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
CRediT authorship contribution statement
Dimitrios I. Bourdas: Conceptualization, Methodology, Investigation, Validation, Formal analysis, Resources, Writing - original draft, Writing - review & editing, Supervision, Project administration. Nickos D. Geladas: Conceptualization, Writing - review & editing.
Declaration of Competing Interest
The authors declare that they have no conflict of interest.
Acknowledgments
We are indebted to the subjects for their enthusiastic and consistent participation in the present study. Furthermore, we are grateful to Theodoros Tsakiris, Konstantinos Pavlakis, Despoina Triantafillou, and Athanasios Konstantopoulos for their assistance with data collection.
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2021, MethodsXCitation Excerpt :In 2011, at the XIV International Conference On Environmental Ergonomics, the first empirical data were presented, as far as we know, which were showed that five repeated apneas with face immersion in cold water increase the time to exhaustion at 150% of peak power output [6]. Few years later, a research paper originally published by D. Bourdas and N. Geladas in 2021, presented data derived from novice to apnea male subjects which revealing, that five repeated apneas maximal efforts with face immersion in cold water improve oxygen delivery to skeletal muscles and increase time to exhaustion (11.3%) in subsequent high-intensity exercise of short-duration (i.e., using the same experimental design us earlier) without being further affected (11.7%) by apnea training of two weeks [7]. In this section, technical information for the Pre Exercise Apneas (PEA) protocol procedure is presented.