Dr.Biol., member-correspondent RAS, Professor N.A. Fudin¹
PhD S.Ya. Klassina¹
PhD S.N. Pigareva¹
Dr,Med., Professor Y.E. Vagin^2
1P.K. Anokhin Research Institute of Normal Physiology, Moscow
²I.M. Sechenov First Moscow State Medical University, Moscow

Keywords: sports, exercise to muscular failure, hypoventilation breathing, hypoxic tolerance, physical working capacity, physiological penalty.

Introduction. Arbitrary control of respiration and physiological peculiarities of interaction between spontaneous effects and reflexive humoral stimuli in the new breathing stereotype formation process have been well studied today [1, 2, 5, 6]. It was found that, during exercise to muscular failure, hypoventilation breathing not only enhances hypoxic tolerance but also increases the sympathetic effects on the heart, increases the stroke volume and minute blood volume, tissue oxygen utilization, "economization" of respiration, which in the end leads to a significant improvement of physical working capacity [8, 9]. However, the nature of the influence of hypoventilation breathing on the functionality and physical working capacity of athletes with different levels of training remains an open question.

Objective of the study was to analyze the effects of voluntary hypoventilation breathing on physical working capacity and functional status of qualified athletes during exercise to muscular failure.

Methods and structure of the study. Sampled for the study were 25 individuals (18-20 year--old males), including 11 qualified athletes and 14 occasionally sporting individuals.

All of them were examined twice, and in both cases they were asked to perform a step load test to muscular failure on a cycle ergometer (at the load power of 160 Watts). Moreover, the first testing was carried out before the hypoventilation breathing training, the second one - after it. The hypoventilation breathing technique teaching process was based on the respiratory training focused on the formation in the testees of the slow breathing pattern on verbal instruction. The training sessions were carried out 3 times a week (4 weeks in total) 1.5-2 hours each according to the system as follows: short inhale - 1.2 sec, short exhale - 1.5 sec, a long, 7-10 sec, pause. For the rest of the week, the testees consolidated their hypoventilation breathing skills on their own, performing inspiration breath holds 3 times a day [5, 6].

During the study, the subjects were in the following functional statuses: "background" (2.5 min); "warm-up" (1 min), "exercise stress test to failure" at the load power of 160 Watts, "recovery" (6 min), "foreground" (2.5 min). the examination scheme is presented in Fig. 1.

Fig. 1. Examination scheme

The exercise stress test was conducted using the cycle ergometer "Sports Art 5005" at the constant cadence of 1 rps. The ECG and  pneumogram test was carried out by means of the digital ECG system "Poly-Spectrum-8" (Neurosoft, Russia). The pedaling speed was registered using "SIGMA – bc-509" (Germany) equipment with its sensor being attached to a pedal of the cycle ergometer.

The following physiological parameters were estimated based on the ECG and  pneumogram rates: heart rate (HR, bpm) and respiratory rate (RR, 1/min). We measured the blood oxygen saturation level (SaO2%) using a finger sensor, and the time of exercise to muscular failure (T-failure, sec). The following hemodynamic indicators were calculated according to the formula: stroke volume (SV, ml) and minute blood volume (MBV, l/min) [3], physiological penalty for exercise to muscular failure:

ρ=√σ_HR²+ σ_RR²

where σ_HR  and σ_RR – relative shifts in HR and RR at the moment of muscular failure versus the baseline indices (background) (%) [4].

In the back- and foreground, we measured the subjects' blood pressure (mmHg) by the Korotkov's method, as well as the external respiration indices (RR, 1/min, respiratory minute volume (RMV), l/min) and timed inspiratory capacity (b/h, sec). We evaluated the subjective general state (sam, points) on a five-point scale and recorded subjective complaints. All the subjects were informed in detail on the ongoing experiment and gave their written consent to participate. The experimental program was approved by the Institutional Review Board of the FSBSI P.K. Anokhin Research Institute of Normal Physiology.

Results and discussion. The level of physical working capacity during exercise to muscular failure was determined by the time of exercise to muscular failure (T-failure, sec) (Fig. 2).

Fig. 2. Mean time of exercise to muscular failure (Т-failure, sec) in qualified athletes before and after hypoventilation breathing training.

Legend: * – p<0.05 is the level of significance of differences.

It can be seen that after the hypoventilation breathing training the athletes' physical working capacity level increased significantly - from 198.0±37.2 to 523.3±118.5 sec (p<0.05), which indicated the improvement of their physical working capacity [7]. Regarding the efficiency of the work performed, it is necessary to consider the physiological penalty, which the body "paid" for this work (Fig. 3).

Fig. 3. Mean physiological penalty when exercising to muscular failure (ρ, %) in athletes before and after hypoventilation breathing training.

Legend: * – p<0.05 is the level of significance of differences.

It can be seen that after the hypoventilation breathing training against the background of the extended time of exercise to muscular failure, the physiological penalty for the work performed increased significantly - by 20.8% (p<0.05). We assume that the increase of the physiological penalty during the hypoventilation breathing was not only due to the physiological peculiarities of the athletes but also due to the significant increase in the time of exercise to muscular failure.

Table 1 presents the athletes' physiological indicators at the moment of failure.

Table 1. Effects of hypoventilation breathing on athletes' cardiorespiratory indices at the moment of failure to perform exercise before and after hypoventilation breathing training

Legend. Here and Tables 2, 3: * – p<0.05 – is the level of significance of differences before and after hypoventilation breathing training.

As the Table shows, after the hypoventilation breathing training, there was a significant increase in the time of exercise to muscular failure (T-failure, p<0.05), increase in the HR (p<0.05); the RR and level of blood oxygen saturation tended to decrease, but the subjective general state of the testees tended to improve. It should be noted that at the moment of failure the HR and RR reached their physiological limits.

We believe that the hypoventilation breathing technique as a means to stimulate man's physical working capacity exerts diverse effects on individuals with different levels of physical fitness.

We conducted a comparative analysis of the effects of hypoventilation breathing on man's physical working capacity and functional indicators of individuals with different levels of physical fitness: 14 untrained and 11 trained subjects (athletes). The results of the analysis are presented as the relative shifts of the indicator (Tables 2, 3).

Table 2. Relative shifts in background physiological indices after hypoventilation breathing training in trained and untrained subjects, %

Table 3. Relative shifts (%) in physiological indices at the moment of failure after hypoventilation breathing training in trained and untrained subjects

Conclusion. It was shown that hypoventilation training develops increased hypoxic tolerance and physical working capacity in athletes against the background of "economization" of their respiratory function and stability of blood oxygenation.

References

1. Breslav I.S. Arbitrary control of respiration in man. Leningrad: Nauka publ, 1975. 152 p.
2. Breslav I.S., Glebovskiy V.D. Respiration control. Moscow: Nauka publ, 1981. 280 p.
3. Karpman V.L., Lyubina B.G. Circulatory dynamics in athletes. Moscow: Fizkultura i sport publ., 1982, 135 p.
4. Ryzhikov G.V., Klassina S.Ya. Space-time structure of "quantum" of controller's professional activity and its physiological support. Human physiology, 1984, vol. 10, no. 1, pp. 144-152.
5. Fudin N.A. Physiological feasibility of voluntary regulation of breathing in athletes. Teoriya i praktika fiz. kultury, 1983, no. 2, pp. 21-22.
6. Fudin N.A., Sudakov K.V. [ed.] Gas homeostasis (voluntary formation of new breathing stereotype). Tula: Tula publ., 2004, 216 p.
7. Fudin N.A., Klassina S.Y., Vagin Y.E. Effects of hypoventilation breathing on physical working capacity during exercise to failure. Teoriya i praktika fiz. kultury, 2016, no. 12, pp. 55-57.
8. Fudin N.A., Klassina S.Y., Pigareva S.N. Correlation of muscular and cardiovascular system characteristics at step load in persons engaged in physical culture and sport. Human Physiology. 2015. v. 41. 4. pp. 82-90.
9. Fudin N.A., Klassina S.Y., Pigareva S.N., Vagin Y.E. Muscle and cardiovascular indicators in persons engaged in physical culture and sport during muscular failure.  Teoriya i praktika fiz. kultury. 2015. no. 11. pp. 18-20.

Corresponding author: klassina@mail.ru

Abstract

Objective of the study was to analyze the effects of voluntary hypoventilation breathing on physical working capacity and functional status of qualified athletes during exercise to muscular failure. The study involved 25 young males with different physical fitness levels. All of them were examined twice, and in both cases they were asked to perform a step load test to muscular failure on a cycle ergometer. Moreover, the first testing was carried out before the hypoventilation breathing training, the second one - after it. The subjects’ condition was evaluated at rest and during the stress test. We registered the ECG and pneumogram, heart rate and respiration rate, time of exercise to muscular failure and its "physiological penalty", external respiration rates and level of blood oxygen saturation. Before and after the testing, blood pressure and timed inspiratory capacity were measured. The hemodynamic parameters were estimated by means of a calculation. It was shown that hypoventilation training develops increased hypoxic tolerance and physical working capacity in athletes against the background of "economization" of their respiratory function and stability of blood oxygenation.