Optimization of function of breath by means of training with additional resistive resistance

Research on studying influence of the rate of muscular training in conditions of additional resistive resistance to breath on a level of physical working capacity, aerobic productivity and a functional condition of system of breath was performed. It is shown, that regular muscular loadings in a combination to resistive resistance to breath in a mode of an interval exposition provide an increase of profitability and efficiency of functioning of breathing system as expressed in increase of expiratory force respiratory muscles, rationalization of parity of volumetric-time parameters of breath pattern that promotes more effective gas exchange and decrease in power cost of respiratory movements and as a result leads to increase in aerobic productivity and growth of the general and special working capacity. At continuous exposition of resistive resistance against a background of muscular training, the increase of inspiratory force of respiratory muscles, increase of functional capacity of system of breath were revealed at physical activity as well as a significant gain of the general physical working capacity.     

Does the respiratory system limit the aerobic working capacity of humans?

The question concerning respiratory function reserves among the factors determining the maximal power of muscular work is considered. Even in strenuous physical exercise, pulmonary ventilation does not exceed a rather constant level for every individual. Studies conducted using the programmed isocapnic hyperpnea method developed by the authors demonstrated that this level precisely reflects the functional respiratory reserve that is one of the factors limiting maximal work performance intensity. Under normal conditions, the functional respiratory reserve is 20 to 40% less than the so-called maximal breathing capacity (MBC) determined in a test, which requires voluntarily forcing respiratory efforts and exorbitant energy expenditure for the respiratory muscles performance. Therefore, the MBC should be regarded only as a parameter of ventilatory forced capacity used in extreme situations such as competitive athletic loading or in more resistive breathing when decreased respiratory system reserves become a leading factor rigidly limiting aerobic working capacity. A scheme is given that illustrates the ambiguous role of the respiratory system in this aspect.     

Development of the Energetics of Muscular Exercise with Age: Summary of a 30-Year Study: I. Structural and Functional Rearrangements

The series of articles summarizes a 30-year study on the development of skeletal muscles, bioenergetics of muscular exercise, and physical working capacity with age in elementary and secondary school students. Communication I deals with the growth of human skeletal muscles and age-related changes in their fiber composition and the main parameters of aerobic working capacity. The key periods of growth were determined and a substantial rearrangement of skeletal muscle composition and associated age-related changes in aerobic and anaerobic working capacity were found in 7- to 17-year-old boys.__________Translated from Fiziologiya Cheloveka, Vol. 31, No. 4, 2005, pp. 37–42.Original Russian Text Copyright © 2005 by Kornienko, Son’kin, Tambovtseva.     

Hindlimb muscular contraction reflexly decreases total pulmonary resistance in dogs

We have previously shown that contraction of the gracilis muscles of anesthetized dogs reflexly relaxes tracheal smooth muscle. We have also found that electrical stimulation of these afferents decreases total pulmonary resistance (TPR), a calculation that provides a functional index of airway caliber. Despite these findings, we have yet to show that muscular contraction reflexly decreases TPR. Therefore, in 11 alpha-chloralose-anesthetized dogs, we contracted the hindlimb muscles by electrically stimulating the L6-L7 ventral roots while measuring TPR breath by breath. We found that static contraction decreased TPR from 12.6 +/- 1.1 to 10.4 +/- 0.9 cmH2O X l-1 X s (P less than 0.05). This decrease was reflex in origin because it was prevented by section of the spinal roots innervating the working hindlimb. Repetitive twitch contractions (5 Hz) also reflexly decreased TPR, but the effect was smaller than that evoked by static contraction. The reflex decreases in TPR evoked by contraction were unaffected by propranolol but were abolished by atropine. We conclude that muscular contraction dilates the airways by a reflex mechanism whose efferent arm consists of a withdrawal of cholinergic input to airway smooth muscle.     

The Phenomenon of Refusal in Muscular Activity. The Role of the Respiratory System

Among the factors leading to the refusal to continue muscular work, afferent impulsation carrying information about the efforts developed by the working muscles and about the respiratory function tension is noteworthy. Based on this information, the integral self-rating of the intensity of the physical load and its endurance is formed in the sensory CNS sphere, with one of the signals to stop the work being the feeling of shortness of breath. Under the cyclic working conditions, the so-called critical power load, which is high enough but does not lead to a refusal so far, enabling one to perform the maximum amount of useful work, appears to be the most effective. A question is posed as to the possibility of using an active choice of preferable load intensity by an individual in order to develop a method for determining the optimal work power according to the functional state of the body.     

Hardware and software for EMG recording and analysis of human respiratory muscles

This paper presents a new hardware and software system that allows not only recording the EMG of different groups of the respiratory muscles but also performing its amplitude-frequency analysis to determine the change in the contribution to the function of breathing of the respiratory muscles and detect early signs of fatigue of the respiratory muscles. The presented system can be used for functional diagnostics of breath in patients and healthy subjects and athletes.     

The respiratory system as an exercise limiting factor in normal sedentary subjects.

The present study was undertaken to investigate the respiratory system as an exercise limiting factor. Breathing and cycle endurance (i.e. the time until exhaustion at a given performance level) as well as physical working capacity 170 (i.e. the exercise intensity corresponding to a heart rate of 170 beats.min-1 on a cycle ergometer) were determined in four healthy sedentary subjects. Subsequently, the subjects trained their respiratory system for 4 weeks by breathing daily about 90 l.min-1 for 30 min. Otherwise they continued their sedentary lifestyle. Immediately after the respiratory training and 18 months later, all performance tests carried out at the beginning of the study were repeated. The respiratory training increased breathing endurance from 4.2 (SD 1.9) min to 15.3 (SD 3.8) min. Cycle endurance was improved from 26.8 (SD 5.9) min to 40.2 (SD 9.2) min whereas physical working capacity 170 remained essentially the same. During the endurance cycling test in the respiratory untrained state, the subjects continuously increased their ventilation up to hyperventilation [ventilation at exhaustion = 96.9 (SD 23.6) l.min-1] while after the respiratory training they reached a respiratory steady-state without hyperventilation [ventilation at exhaustion = 63.3 (SD 14.5) l.min-1]. The absence of this marked hyperventilation was the cause of the impressive increase of cycle endurance in normal sedentary subjects after respiratory training. The effects gained by the respiratory training were completely lost after 18 months. Our results indicated that the respiratory system was an exercise limiting factor during an endurance test in normal sedentary subjects.     

Non-linear dynamics in muscle fatigue and strength model during maximal self-perceived elbow extensors training

Our aim was to determine the dynamics in muscle strength increase and fatigue development during repetitive maximal contraction in specific maximal self-perceived elbow extensors training program. We will derive our functional model for m. triceps brachii in spirit of traditional Hill’s two-component muscular model and after fitting our data, develop a prediction tool for this specific training system. Thirty-six healthy young men (21±1.0 y, BMI 25.4±7.2 kg/m²), who did not take part in any formal resistance exercise regime, volunteered for this study. The training protocol was performed on the isoacceleration dynamometer, lasted for 12 weeks, with a frequency of five sessions per week. Each training session included five sets of 10 maximal contractions (elbow extensions) with a 1 min resting period between each set. The non-linear dynamic system model was used for fitting our data in conjunction with the Levenberg–Marquardt regression algorithm. As a proper dynamical system, our functional model of m. triceps brachii can be used for prediction and control. The model can be used for the predictions of muscular fatigue in a single series, the cumulative daily muscular fatigue and the muscular growth throughout the training process. In conclusion, the application of non-linear dynamics in this particular training model allows us to mathematically explain some functional changes in the skeletal muscle as a result of its adaptation to programmed physical activity—training.     

Breathing,voice, and movement therapy: Applications to breathing disorders

Elsa Gindler (1885–1961) developed a holistic approach to the human body and psyche via the movement of breath. Gindler experimented with movements to strengthen the deeper layers of the muscular system and improve the circulation of oxygen, movements that reduced tensions that had been preventing the breathing muscles from functioning properly. Subsequently, she founded a school for breathing and body awareness. The biggest breathing muscle in the human body is the diaphragm, the lowering of which can only take place when the jaw and the throat are relaxed, the belly is free, and the psoas (major and minor) and hip joints allow free leg-movement and flexibility in the lower back. When these conditions do not obtain, the body compensates by lifting the shoulders, pulling up the chest bone, and contracting the sphincter muscles in the throat, movements which weaken the muscles which assist the breathing process. Thus, the compensatory muscles are overburdened and the fine organization of the body is disturbed; the natural capacity to use the breath as a healing force is lost. The goal of breath therapy is to recognize and reestablish this capacity. Training sessions are devoted to relaxation; to exercises to rebuild muscle tone, strengthen weakened muscles, release contracted areas, and the use of the voice to stimulate the respiratory system. Sessions typically consist of (a) relaxation, (b) activation (experimenting with new, freer ways of moving), and (c) integration (application to everyday life). The therapist analyzes incidents of stress in the client's life where breathing is likely to be disturbed. This is especially important for asthmatics who can learn how to deal with an attack by relaxing rather than contracting. This work is especially beneficial for problems in (a) the skeletal structure, (b) respiration, (c) vital organs, and (d) general symptoms.     

Efficacy of two intervention approaches on functional walking capacity and balance in children with Duchene muscular dystrophy

Objectives:Children with Duchene muscular dystrophy have weak muscles, which may impair postural adjustments. These postural adjustments are required for gait and dynamic balance during the daily living activities. The aim was to compare between the effect of bicycle ergometer versus treadmill on functional walking capacity and balance in children with Duchenne muscular dystrophy.Methods:Thirty boys aged from 6 to 10 years old diagnosed as Duchene muscular dystrophy participated in this study. Children were assigned randomly into two groups (A&B). Children in group (A) underwent a designed program of physical therapy plus aerobic exercise training in form of bicycle ergometer while, group (B) received the same program as group (A) and aerobic exercise training by treadmill for one hour, at three times a week for three successive months. Functional walking capacity and balance were assessed before and after treatment by using the 6-minute walk test and Biodex balance system equipment respectively.Results:The post treatment results revealed significant difference in all measured variables (P<0.05) as compared with its pre-treatment results. Post-treatment values indicated that there was a significant difference in all measured variables in favor of group B.Conclusions:treadmill training as an aerobic exercise can improve walking capacity and balance more effectively than bicycle ergometer in children with Duchenne muscular dystrophy.     

Exercise induced increases in muscle fiber number

The effect of weight-lifting, which induced muscular enlargement, on fiber number was tested in the flexor carpi radialis muscle by operantly conditioning 6 cats to flex their right wrist against increasing resistance for an average of 101 weeks. The left was used as a control. At the end of training, the cats were performing "one-arm" lifts with an average of 57% of their body weight. There was an 11% greater muscle weight (P less than 0.01) and 9% (P less than 0.02) more fibers in the exercised muscles from the right limb than in the left. This study using a different method, supports our earlier observations that prolonged weight-lifting exercise significantly increases the total number of muscle fibers.     

Allometric dependences of oxygen transport parameters in skeletal muscles during ontogenesis of domestic fowl

In domestic fowl, from day 10 of embryogenesis to six month of postnatal life, investigation into the white glycolytic pectoral and red oxidative gastrocnemius muscles allometric dependences of the structural and functional parameters providing muscular fibres by oxygen: speed of breath of an isolated muscular fibre, size of a surface of an external membrane of mitochondria in a fibre, its permeability to oxygen, density of the capillaries located around of a fibre and in all muscle, volumetric speed of a muscular blood flow, and connection of speed of breath of muscular fibres with weight of a body of a bird.     

Resistance training enhances the stability of sensorimotor coordination

Strategies for the control of human movement are constrained by the neuroanatomical characteristics of the motor system. In particular, there is evidence that the capacity of muscles for producing force has a strong influence on the stability of coordination in certain movement tasks. In the present experiment, our aim was to determine whether physiological adaptations that cause relatively long-lasting changes in the ability of muscles to produce force can influence the stability of coordination in a systematic manner. We assessed the effects of resistance training on the performance of a difficult coordination task that required participants to synchronize or syncopate movements of their index finger with an auditory metronome. Our results revealed that training that increased isometric finger strength also enhanced the stability of movement coordination. These changes were accompanied by alterations in muscle recruitment patterns. In particular, the trained muscles were recruited in a more consistent fashion following the programme of resistance training. These results indicate that resistance training produces functional adaptations of the neuroanatomical constraints that underlie the control of voluntary movement.     

The relation of the reactivity of the human respiratory system, mental and physical work capacity and metabolic characteristics during a 1-year stay in the mountains

People with the highest rates of mental working capacity staying for a year at an altitude of 1680 m below sea level are characterized by less pronounced responses of respiration to moderate hypoxia and great ventilatory response to maximally endured hypoxic action, by higher glucose content in blood and physical working capacity. Many relationships typical of the middle mountains are inverse ones under conditions of a one-year stay at an altitude of 3650 m below sea level. In the case of a total decrease in indices of mental and physical working capacity people with the highest rate of information processing are characterized by less reactivity of the respiratory system, greater resistance to ultimate hypoxia, lower glucose concentration, less physical working capacity.     

Physiological effects of low-intensity strength training without relaxation

The effects of low-intensity strength training without relaxation (LISTR) on the force-velocity properties of hip and knee extensor muscles, the power endurance of the knee extensor muscles, and the aerobic performance of the body were studied. The difference between the LISTR and classical strength training (CST) is that the working muscle groups do not relax at the extreme points of the range of motion. The study was performed in two groups each comprising nine young physically active men who trained three times a week for eight weeks. The study showed that LISTR increased the maximum voluntary force to about the same extent as CST, but this was achieved with lower training loads. Moreover, LISTR did not lead to a decrease in the local muscular work capacity, which is usually observed during CST.     

Exercise-induced respiratory muscle fatigue: implications for performance.

It is commonly held that the respiratory system has ample capacity relative to the demand for maximal O(2) and CO(2) transport in healthy humans exercising near sea level. However, this situation may not apply during heavy-intensity, sustained exercise where exercise may encroach on the capacity of the respiratory system. Nerve stimulation techniques have provided objective evidence that the diaphragm and abdominal muscles are susceptible to fatigue with heavy, sustained exercise. The fatigue appears to be due to elevated levels of respiratory muscle work combined with an increased competition for blood flow with limb locomotor muscles. When respiratory muscles are prefatigued using voluntary respiratory maneuvers, time to exhaustion during subsequent exercise is decreased. Partially unloading the respiratory muscles during heavy exercise using low-density gas mixtures or mechanical ventilation can prevent exercise-induced diaphragm fatigue and increase exercise time to exhaustion. Collectively, these findings suggest that respiratory muscle fatigue may be involved in limiting exercise tolerance or that other factors, including alterations in the sensation of dyspnea or mechanical load, may be important. The major consequence of respiratory muscle fatigue is an increased sympathetic vasoconstrictor outflow to working skeletal muscle through a respiratory muscle metaboreflex, thereby reducing limb blood flow and increasing the severity of exercise-induced locomotor muscle fatigue. An increase in limb locomotor muscle fatigue may play a pivotal role in determining exercise tolerance through a direct effect on muscle force output and a feedback effect on effort perception, causing reduced motor output to the working limb muscles.     

Strategies of adaptation of small arteries in diaphragm and gastrocnemius muscle to aerobic exercise training

Aerobic exercise training is associated with adaptive changes in skeletal muscles and their vascular bed; such changes in individual muscles may vary depending on their characteristics and recruitment. This study was aimed at comparing the effects of eight-week treadmill training on the locomotor and respiratory muscles in rats. The training course increased the aerobic performance in rats, which was evidenced by an increase in maximum O₂ consumption and a decrease in the blood lactate concentration in ramp test. The succinate dehydrogenase activity was increased in the red portion of the gastrocnemius muscle, but not in the diaphragm of trained rats. Arterial segments were isolated from feed arteries and studied by wire myography. The relaxation in response to acetylcholine in gastrocnemius arteries in trained animals was higher as compared with controls (due to higher NO production), while contractile responses to noradrenaline (in the presence of propranolol) were not changed. On the contrary, the endothelial function of diaphragm arteries was not affected by training, but contractile responses to activation of α-adrenoceptors were markedly increased. Thus, aerobic training may increase the blood supply rate to both locomotor and respiratory muscles, but the underlying regulatory mechanisms are different. The results obtained allow us to reveal the physiological mechanisms that determine the physical performance of the body under conditions of compromised functioning of the respiratory system.     

Resistive loading and mechanisms regulating respiration

In experiments on anesthetized cats, switch on of additional inelastic respiration resistance (resistive load) produced, apart from slowing of the respiratory flows, an increase in the activity of motoneurons and inspiratory intrathoracic pressure. Bilateral vagotomy resulted in disappearance of resistive load-induced elevation of the phrenic nerve activity, but did not abolish the growth of the inspiratory effort. Analysis of the evidence obtained indicates that activation of phrenic motoneurons associated with increased respiration resistance is underlain by prolongation of the inspiratory phase that is consequent on relaxation of the inspiratory inhibition. It is suggested that, in addition to the mechanism depicted, the compensatory reaction to the resistive load involves, apart from diaphragm participation, other inspiratory muscles as well as enhanced contractions of respiratory muscles provided by the properties of muscular fiber.     

Physical working capacity and energy supply of muscle function during postnatal human ontogeny

On the basis of the results of our studies and literature data, an analysis of the physiological mechanisms responsible for the multifold increase in the physical working capacity during human development has been performed. Physiological and biochemical studies have shown that the aerobic energy system already has a high capacity during the second period of childhood, and the further increase in working capacity is mainly provided by the development of anaerobic mechanisms of energy supply. The maturation of mechanisms of energy production is related to considerable changes in the activity of tissue enzymes and radical rearrangement of the composition of muscular fibers. Puberty considerably influences the development of anaerobic muscle energetics in boys due to stimulation of the growth of type II fibers by testosterone. It has been shown that widespread tests for assessment of physical working capacity mainly reflect changes in the power of energy systems and only in rare cases may be used to characterize changes in their capacity. However, the capacity parameters, which depend to a greater extent on the quality of regulation at the cellular, tissue, and body levels, show multifold growth during ontogeny, which corresponds to the actual increase in the working capacity in the period from childhood to youth. A classification of tests of physical working capacity is proposed. The use and development of this classification may facilitate the development of new tests and an increased efficiency of testing involved in solving various applied and fundamental problems.     

Investigations of the validity of e.a. müller's "leistungspulsindex" (author's transl)]

In order to obtain a critical review of E.A. Müller's "Leistungspulsindex", we worked out a functional representation of that index, using a simple physiologic-mathematic model of the oxygen transport system. We found that the LPI is influenced by the economy of the oxygen transport system and that it is inversely proportional to stroke volume, caloric coefficient, and to the efficiency of muscular work. Based on the theoretic analysis we tried to interpret the results of an investigation carried out with pupils of an coeducative intermediate school (years of birth 1964, 1965, 1966). We obtained statistically significant correlations (p less than 0.1%) between LPI and parameters characterizing performance capacity (PWC170, heart rate at 100 W work load) and between LPI and body weight. The results of both the theoretic and experimental investigation indicate a dependence of the LPI on factors influenced by physical training processes, but no evidence was found, however, on an interrelationship between LPI and congenital factors of physical performance.