Conference Paper

The Effects of Hypercapnic-Hypoxic Training on Strength Respiratory Muscles and Swimming Performance of Elite Swimmers

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Abstract

Introduction. Hypercapnia is known as a powerful cerebral vasodilator and ventilatory stimulants and represents an elevated partial pressure of carbon dioxide (pCO2) in arterial blood (Ivancev, 2009). Breathing muscles work while swimming is less economical because they have to, because of the short breaths; contract faster to gain a greater respiratory volume (Kapus, 2008). Specifically, breathing is difficult because the muscles involved in breathing performed additional work (Lomax & McConnell, 2003). The aim of this research is to determine the effects of hypercapnic-hypoxic training on result at 100 meters crawl swimming, together with determining respiratory muscles strength. Methods . In order to collect data testing is carried out on 26 top swimmers (control (C, n = 14) and experimental (E, n = 12)) in the following tests: the strength of respiratory muscles, the result of the 100m freestyle swim and the number of breaths during that race. Results. Results based on Wilks'Lambda = 0.42790, p = 0.000 at significant level p<0.05, we see that there is a statistically significant difference in multivariate space progress between groups "repeated measures MANOVA". A series of two-way univariate analysis of variance "repeated measures ANOVA" showed that all the variables show statistically significant differences in progress between groups (MIP, p = 0.006, MEP, p <0.0001, R100, p <0.0001, FB, p = 0.000). Discussion. Because of the increased strength of respiratory muscles in swimmers of experimental group it is possible that there was an increased volume of breathing with each inhale and exhale. Greater amount of air in the lungs has a positive effect on the amount of oxygen available, the elimination of excess CO2 and the very buoyancy of swimmers. They were also able to achieve better result in 100m crawl swim as well as a reduced number of breaths during that swim. Breathing during swimming interferes with propulsion and causes time imbalance between the two strokes and is recommended for swimmers (Lerda et al., 2001; Seifert et al., 2007), especially in shorter races to try to swim with the smaller number of breaths

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Chapter
The function of the respiratory system is to move oxygen from the air of the environment to the mitochondria of the cells where it is utilized, and move carbon dioxide in the opposite direction. The processes include pulmonary ventilation, diffusion, pulmonary blood flow, gas exchange, mechanics of breathing, control of ventilation, and peripheral gas exchange.
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This study analyses the effect of breathing on propulsion by comparing the coordination of arm movements and the relative duration of stroke phases in two swim conditions: crawl with and crawl without breathing. In this comparison, specific attention is given to skill level and swim velocity. Twenty-four male swimmers constituted two groups based on performance level. All swam at two different velocities, corresponding to the paces appropriate for the 100m and 800m in the two breathing conditions. The different stroke phases and the arm coordination were identified by video analysis. According to Chollet et al (2000), arm coordination was quantified using an index of coordination (IdC), which expresses the three major models: opposition, catch-up and superposition. Opposition, where one arm begins the pull phase when the other is finishing the push phase; catch-up, which has a lag time (LT) between propulsive phases of the two arms; and superposition which describes an overlap in the propulsive phases. The IdC is an index which characterises coordination patterns by measure of LT between propulsive phases of each arm. The results show that breathing while swimming increases the discontinuity in the propulsive action of the arms: IdC is lower in crawl with breathing (-3.05%). IdC increases with skill level (IdC more expert=0.06%, IdC less expert=-3.22%) and velocity (IdC100-m=0.05%, IdC800-m=-3.33%). IdC is positively correlated to the durations of the propulsive phases and negatively to the durations of the non-propulsive phases. The coefficients of correlation are between ±0.58 and ±0.95. The more expert swimmers have a greater capacity to adapt breathing style to the biomechanical constraints caused by the motor actions of the arms. While swimming with breathing, the more experts attempt to take advantage of the longer period of gliding motion provided by the higher relative duration of the entry and catch phase (+1.66%). The less expert swimmers who, on the contrary, shorten the catch time (-1.70%) and lengthen the durations of the push (+2.84%) and recovery (+2.09%), appear to opt for an increase in the duration of inhalation. This observation may be extended to the comparison between swimming speeds. At slower speeds, less expert swimmers increase arm recovery time (+5.55%) and the more expert increase the time involved in entry and catch (+4.43%).
Article
PURPOSE: This study evaluated the influence of simulated 20- and 40-km time trials upon postexercise inspiratory muscle function of trained competitive cyclists. In addition, we examined the influence of specific inspiratory muscle training (IMT) upon the responses observed. METHODS: Using a double-blind placebo-controlled design, 16 male cyclists (mean +/- SEM VO2max 64 +/- 2 mL.kg-1.min-1) were assigned randomly to either an experimental (IMT) or sham-training control (placebo) group. Maximum static and dynamic inspiratory muscle function was assessed immediately pre- and <2, 10, and 30 min post-simulated 20- and 40-km time trials before and after 6-wk of IMT or sham-IMT. RESULTS: Maximum inspiratory mouth pressure (P0) measured within 2 min of completing the 20- and 40-km time trial rides was reduced by 18% and 13%, respectively, and remained below preexercise values at 30 min. The 20- and 40-km time trials induced a reduction in inspiratory flow rate at 30% P0 by 14% and 6% in the IMT group versus 13% and 7% for the placebo group, and also remained below preexercise values at 30 min. There was also a significant slowing of inspiratory muscle relaxation rate postexercise; these trends were almost completely reversed by 30 min postexercise. Significant improvements in 20- and 40-km time trial performance were seen (3.8 +/- 1.7% and 4.6 +/- 1.9%, respectively; P < 0.05) and postexercise reductions in muscle function were attenuated with IMT. CONCLUSION: These data support existing evidence that there is significant global inspiratory muscle fatigue after sustained heavy endurance exercise. Furthermore, the present study provides new evidence that performance enhancements observed after IMT are accompanied by a decrease in inspiratory muscle fatigue.
Article
Even though research interest is typically greatest for questions pertaining to central tendency and, to a lesser degree, variability, knowledge about the nature of a measure or variable is impoverished when information about the shape of the frequency distribution is ignored. This paper makes the point that descriptive and inferential measures of non-normality should be a routine part of research reporting, along with graphic displays of the frequency distribution of important variables. This point is especially true for research involving measures with non-arbitrary metrics where the shape of the distribution is not affected by measurement artifacts.
In the present study pulmonary function tests of two different groups of athletes, swimmers and runners were studied and compared. Thirty swimmers who used to swim a distance of two to three kilometers per day regularly were compared with age, sex, height, and weight matched thirty middle distance runners. Runners and swimmers selected for this study were undergoing training since last three years. Tidal Volume (TV), forced Vital Capacity (FVC). Forced expiratory volume in one second (FEV1) and maximum voluntary ventilation (MVV) were higher in swimmers than runners. Swimming exercise affects lung volume measurements as respiratory muscles including diaphragm of swimmers are required to develop greater pressure as a consequence of immersion in water during respiratory cycle, thus may lead to functional improvement in these muscles and also alterations in elasticity of lung and chest wall or of ventilatory muscles, leading to an improvement in forced vital capacity and other lung functions of swimmers than runners.
Article
Accumulating evidence over the past 25 years depicts the healthy pulmonary system as a limiting factor of whole-body endurance exercise performance. This brief overview emphasizes three respiratory system-related mechanisms which impair O(2) transport to the locomotor musculature [arterial O(2) content (C(aO(2))) × leg blood flow (Q(L))], i.e. the key determinant of an individual's aerobic capacity and ability to resist fatigue. First, the respiratory system often fails to prevent arterial desaturation substantially below resting values and thus compromises C(aO(2)). Especially susceptible to this threat to convective O(2) transport are well-trained endurance athletes characterized by high metabolic and ventilatory demands and, probably due to anatomical and morphological gender differences, active women. Second, fatiguing respiratory muscle work (W(resp)) associated with strenuous exercise elicits sympathetically mediated vasoconstriction in limb-muscle vasculature, which compromises Q(L). This impact on limb O(2) transport is independent of fitness level and affects all individuals, but only during sustained, high-intensity endurance exercise performed above ∼85% maximal oxygen uptake. Third, excessive fluctuations in intrathoracic pressures accompanying W(resp) can limit cardiac output and therefore Q(L). Exposure to altitude exacerbates the respiratory system limitations observed at sea level, further reducing C(aO(2)) and substantially increasing exercise-induced W(resp). Taken together, the intact pulmonary system of healthy endurance athletes impairs locomotor muscle O(2) transport during strenuous exercise by failing to ensure optimal arterial oxygenation and compromising Q(L). This respiratory system-related impact exacerbates the exercise-induced development of fatigue and compromises endurance performance.
Article
Maximal inspiratory pressures (MIP) and maximal expiratory pressures (MEP) are useful indices of respiratory muscle strength in athletes. The aims of this study were: to describe the strength of the respiratory muscles of Olympic junior swim team, at baseline and after a standard physical training; and to determine if there is a differential inspiratory and expiratory pressure response to the physical training. A cross-sectional study evaluated 28 international-level swimmers with ages ranging from 15 to 17 years, 19 (61%) being males. At baseline, MIP was found to be lower in females (P = .001). The mean values reached by males and females were: MIP(cmH2O) = M: 100.4 (± 26.5)/F: 67.8 (± 23.2); MEP (cmH2O) = M: 87.4 (± 20.7)/F: 73.9 (± 17.3). After the physical training they reached: MIP (cmH2O) = M: 95.3 (± 30.3)/F: 71.8 (± 35.6); MEP (cmH2O) = M: 82.8 (± 26.2)/F: 70.4 (± 8.3). No differential pressure responses were observed in either males or females. These results suggest that swimmers can sustain the magnitude of the initial maximal pressures. Other studies should be developed to clarify if MIP and MEP could be used as a marker of an athlete's performance
Article
Inspiratory muscle training (IMT) has been shown to improve time trial performance in competitive athletes across a range of sports. Surprisingly, however, the effect of specific IMT on surface swimming performance remains un-investigated. Similarly, it is not known whether any ergogenic influence of IMT upon swimming performance is confined to specific race distances. To determine the influence of IMT upon swimming performance over 3 competitive distances, 16 competitive club-level swimmers were assigned at random to either an experimental (pressure threshold IMT) or sham IMT placebo control group. Participants performed a series of physiological and performance tests, before and following 6 weeks of IMT, including (1) an incremental swim test to the limit of tolerance to determine lactate, heart rate and perceived exertion responses; (2) standard measures of lung function (forced vital capacity, forced expiratory volume in 1 s, peak expiratory flow) and maximal inspiratory pressure (MIP); and (3) 100, 200 and 400 m swim time trials. Training utilised a hand-held pressure threshold device and consisted of 30 repetitions, twice per day. Relative to control, the IMT group showed the following percentage changes in swim times: 100 m, -1.70% (90% confidence limits, +/-1.4%), 200 m, -1.5% (+/-1.0), and 400 m, 0.6% (+/-1.2). Large effects were observed for MIP and rates of perceived exertion. In conclusion, 6 weeks of IMT has a small positive effect on swimming performance in club-level trained swimmers in events shorter than 400 m.
Article
The aim of the present study was to assess the influence of 2 different breathing frequencies on the magnitude of inspiratory muscle fatigue after high-intensity front crawl swimming. The influence of different breathing frequencies on postexercise blood lactate ([La]) and heart rate (HR) was also examined. Ten collegiate swimmers performed 2 x 200-m front crawl swims at 90% of race pace with the following breathing frequencies: 1) 1 breath every second stroke (B2), and 2) 1 breath every fourth stroke (B4). Maximal inspiratory pressure (PImax) was measured at the mouth from residual volume before (baseline) and after swimming, in a standing position. The HR and [La] were assessed at rest and immediately at the cessation of swimming. The PImax decreased by 21% after B4 and by 11% after B2 compared with baseline (p < 0.05). The [La] was lower by 15% after B4 than after B2 (p < 0.05). The HR was not significantly different between B2 and B4. These data suggest that there is significant global inspiratory muscle fatigue after high-intensity swimming. Inspiratory muscle fatigue is, however, greater when breathing frequency is reduced during high-intensity front crawl swimming. Respiratory muscle training should be used to improve respiratory muscle strength and endurance in swimmers.
Article
The breathing pattern and ventilatory response to carbon dioxide of 10 experienced divers was compared with that of 10 nondivers of similar age and build. Breathing pattern was described by the equation VE = M (VT - K) and the response to carbon dioxide by VE = S(PCO2 - B). The divers exhibited a value form 27% lower than the nondivers; S was 33% lower. The difference was significant (P less than 0.05) in both cases. B was significantly higher (P less than 0.05) in the divers than nondivers. These differences are not attributable to age, build, or vital capacity. S was well correlated with M when all subjects were considered a single group. Within the diving group no correlation of S and M with diving experience was found.
Article
The purpose of this study was to determine the effect of a reduced ventilatory frequency (Vf) on blood gases and acid-base changes during three intensities of cycling exercise. VO2max and lactate threshold workload (LaT) of six subjects were assessed on a Monark ergometer. Experimental rides were performed 1) with no restriction on Vf (NB) and 2) with a prescribed Vf of 10/min (CFB). Each exercise period consisted of 8 min at 10% of VO2max below the LaT (WI), followed immediately by 8 min at LaT (WII), followed immediately by 8 min at 10% of VO2max above LaT (WIII). Blood was taken from a heated fingertip at the end of each load and analyzed for lactate concentration, pH, PO2, and PCO2. Respiratory exchange was monitored continuously using open circuit indirect calorimetry. Minute ventilation (VE) was significantly reduced by CFB at all three workloads. The reduced VE resulted in lower (p less than 0.05) blood PO2 at each workload (p less than 0.05), however, neither blood lactate nor VO2 were significantly different between CFB and NB for the three loads. Blood [H+] was significantly higher in CFB than NB at all three loads with the greatest difference between trials at WIII (NB: 37.93 +/- 0.68 nM: CFB: 44.77 +/- 1.02 nM). This was accounted for by a significantly higher PCO2 during CFB in WII and WIII (WII, NB: 33.0 +/- 1.4 mmHg, CFB: 35.7 +/- 2.7 mmHg; WIII, NB: 31.2 +/- 1.7 mmHg, CFB: 38.9 +/- 2.4 mmHg).(ABSTRACT TRUNCATED AT 250 WORDS)
Article
The response of the pulmonary system to exercise is well-documented to be quite precise in its homeostatic regulation, highly efficient in terms of its physiologic cost, and operating well within its maximum reserves. Two exceptions to these generalizations are documented here in the highly-trained athlete: 1) the arterial hypoxemia observed in short-term work at a VO2 greater than 4-5 l . min-1, and 2) the tachypneic hyperventilation of long-term, heavy exercise in varying environmental conditions. The potential causes and consequences of these responses are discussed with reference to so-called exercise "limitations". The trained state as a cause of pulmonary limitations is emphasized.
Article
The low impact nature of exercise in the water has increased interest in this form of exercise and specifically in water running as a cross-training modality. It is used as a possible preventative and therapeutic modality for rehabilitation. The high impact nature of land running predisposes the runner to stress of the lower limbs and overuse injuries. The need to reduce impact, as well as provide a low impact or non-weight-bearing condition for rehabilitation, has led runners and their coaches to the water. This increased interest by coaches and their athletes, attending sports medicine physicians and rehabilitative professionals has stimulated research into water immersion to the neck (WI) running. Exercise in the water has long been used by rehabilitative professionals with patients who have physically debilitating conditions (i.e. arthritis, musculoskeletal disorders) as it provides a medium for even those with limited mobility to exercise and relax their muscles. Numerous comparative studies into WI running from a metabolic as well as a training perspective have been published. WI has also long been used to simulate weightlessness for the comparative study of cardiorespiratory function and thermoregulation. WI and the associated cephalad shift in blood volume has implications on exercise responses during WI running exercise. In addition, the non-weight-bearing nature of WI running also raises issues of the cross-training benefits of WI running. WI running style and prior familiarity with the activity have been found to have a direct relationship with the comparability of WI to land running. This review presents current research into WI running, training specificity and comparative physiology.
Article
Respiratory muscle fatigue has been demonstrated following short-term exercise to volitional fatigue, as well as following prolonged submaximal exercise. There is some suggestion that the respiratory muscles of 'athletic' individuals have superior strength and greater fatigue resistance but it is not known whether inspiratory muscle strength influences fatigueability of the inspiratory muscles. The present study examined this question in 24 moderately trained young men. Inspiratory muscle strength was measured at residual volume using a hand held Mouth Pressure Meter before and after an incremental, multistage shuttle run to volitional fatigue. Following the run, there was a significant fall in inspiratory mouth pressures (-10.5 +/- SD 8.2%; p < 0.001 Pre- vs Post Pipeak). The subjects with the weakest inspiratory muscles exhibited significantly greater fatigue than those with the strongest (-17.0 +/- SD 7.8% c.f. 6.8 +/- SD 4.4% for the 25th and 75th percentiles respectively p < 0.01). These data support existing evidence that the respiratory muscles fatigue following high intensity exercise. In addition, they provide new evidence that this phenomenon occurs in moderately trained young men and that the severity of the fatigue is related to the baseline strength of the inspiratory muscles.
Article
Repeated epochs of breath-holding were superimposed to the regular training cycling program of triathletes to reproduce the adaptative responses to hypoxia, already described in elite breath-hold divers [Respir. Physiol. Neurobiol. 133 (2002) 121]. Before and after a 3-month breath-hold training program, we tested the response to static apnea and to a 1-min dynamic forearm exercise executed during apnea (dynamic apnea). The breath-hold training program did not modify the maximal performances measured during an incremental cycling exercise. After training, the duration of static apnea significantly lengthened and the associated bradycardia was accentuated; we also noted a reduction of the post-apnea decrease in venous blood pH and increase in lactic acid concentration, and the suppression of the post-apnea oxidative stress (increased concentration of thiobarbituric acid reactive substances). After dynamic apnea, the blood acidosis was reduced and the oxidative stress no more occurred. These results suggest that the practice of breath-holding improves the tolerance to hypoxemia independently from any genetic factor.
Article
Diving mammals may enhance dive duration by injecting extra erythrocytes into the circulation by spleen contraction. This mechanism may also be important for apneic duration in humans. We studied the speed and magnitude of spleen volume changes evoked by serial apneas, and the associated changes in hematocrit (Hct) and hemoglobin (Hb) concentration, diving response and apneic duration. Three maximal apneas separated by 2 min rest elicited spleen contraction in all ten subjects, by a mean of 49 (27) ml (18%; P<0.001). During the same period, Hct and Hb rose by 2.2 and 2.4% respectively (P<0.01 and P<0.001), and apneic duration rose by 20 s (22% P<0.05). The mean heart rate reduction of the diving response was 15%, which remained the same throughout the apnea series. While the diving response was completely reversed between the apneas, spleen size was not recovered until 8-9 min after the final apnea corresponding with recovery of Hct and Hb. Thus, although the spleen contraction may be associated with the cardiovascular diving response, it is likely to be triggered by different mechanisms, and it may remain activated between dives spaced by short pauses. The two adjustments may provide a fast, quickly reversed, and a slow, but long-lasting, way of shifting to a diving mode in humans.
Article
The efficiency of the respiratory system presents significant limitations on the body's ability to perform exercise due to the effects of the increased work of breathing, respiratory muscle fatigue, and dyspnoea. Respiratory muscle training is an intervention that may be able to address these limitations, but the impact of respiratory muscle training on exercise performance remains controversial. Therefore, in this study we evaluated the effects of a 12-week (10 sessions week(-1)) concurrent inspiratory and expiratory muscle training (CRMT) program in 34 adolescent competitive swimmers. The CRMT program consisted of 6 weeks during which the experimental group (E, n = 17) performed CRMT and the sham group (S, n = 17) performed sham CRMT, followed by 6 weeks when the E and S groups performed CRMT of differing intensities. CRMT training resulted in a significant improvement in forced inspiratory volume in 1 s (FIV1.0) (P = 0.050) and forced expiratory volume in 1 s (FEV1.0) (P = 0.045) in the E group, which exceeded the S group's results. Significant improvements in pulmonary function, breathing power, and chemoreflex ventilation threshold were observed in both groups, and there was a trend toward an improvement in swimming critical speed after 12 weeks of training (P = 0.08). We concluded that although swim training results in attenuation of the ventilatory response to hypercapnia and in improvements in pulmonary function and sustainable breathing power, supplemental respiratory muscle training has no additional effect except on dynamic pulmonary function variables.
Article
Respiratory muscles can fatigue during prolonged and maximal exercise, thus reducing performance. The respiratory system is challenged during underwater exercise due to increased hydrostatic pressure and breathing resistance. The purpose of this study was to determine if two different respiratory muscle training protocols enhance respiratory function and swimming performance in divers. Thirty male subjects (23.4 ± 4.3 years) participated. They were randomized to a placebo (PRMT), endurance (ERMT), or resistance respiratory muscle training (RRMT) protocol. Training sessions were 30 min/day, 5 days/week, for 4 weeks. PRMT consisted of 10-s breath-holds once/minute, ERMT consisted of isocapnic hyperpnea, and RRMT consisted of a vital capacity maneuver against 50 cm H2O resistance every 30 s. The PRMT group had no significant changes in any measured variable. Underwater and surface endurance swim time to exhaustion significantly increased after RRMT (66%, P < 0.001; 33%, P = 0.003) and ERMT (26%, P = 0.038; 38%, P < 0.001). Breathing frequency (f b) during the underwater endurance swim decreased in RRMT (23%, P = 0.034) and tidal volume (V T) increased in both the RRMT (12%, P = 0.004) and ERMT (7%, P = 0.027) groups. Respiratory endurance increased in ERMT (216.7%) and RRMT (30.7%). Maximal inspiratory and expiratory pressures increased following RRMT (12%, P = 0.015, and 15%, P = 0.011, respectively). Results from this study indicate that respiratory muscle fatigue is a limiting factor for underwater swimming performance, and that targeted respiratory muscle training (RRMT > ERMT) improves respiratory muscle and underwater swimming performance.
Article
The goal of this study was to assess the effects of a prolonged expiration (PE) carried out down to the residual volume (RV) during a submaximal exercise and consider whether it would be worth including this respiratory technique in a training programme to evaluate its effects on performance. Ten male triathletes performed a 5-min exercise at 70% of maximal oxygen consumption in normal breathing (NB(70)) and in PE (PE(70)) down to RV. Cardiorespiratory parameters were measured continuously and an arterialized blood sampling at the earlobe was performed in the last 15s of exercise. Oxygen consumption, cardiac frequency, end-tidal and arterial carbon dioxide pressure, alveolar-arterial difference for O(2) (PA(O2) - Pa(O2)) and P(50) were significantly higher, and arterial oxygen saturation (87.4+/-3.4% versus 95.0+/-0.9%, p<0.001), alveolar (PA(O2)) or arterial oxygen pressure, pH and ventilatory equivalent were significantly lower in PE(70) than NB(70). There was no difference in blood lactate between exercise modalities. These results demonstrate that during submaximal exercise, a prolonged expiration down to RV can lead to a severe hypoxemia caused by a PA(O2) decrement (r=0.56; p<0.05), a widened PA(O2) - Pa(O2) (r=-0.85; p<0.001) and a right shift of the oxygen dissociation curve (r=-0.73; p<0.001).
Article
Respiratory work is increased during exercise under water and may lead to respiratory muscle fatigue, which in turn can compromise swimming endurance. Previous studies have shown that respiratory muscle training, conducted five days per week for four weeks, improved both respiratory and fin swimming endurance. This training (RRMT-5) consisted of intermittent vital capacity breaths (twice/minute) against spring loaded breathing valves imposing static and resistive loads generating average inspiratory pressures of approximately 40 cmH2O and expiratory pressures of approximately 47 cmH2O. The purpose of the present study (n = 20) was to determine if RRMT 3 days per week (RRMT-3) would give similar improvements, and if continuing RRMT 2 days per week (RRMT-M) would maintain the benefits of RRMT-3 in fit SCUBA divers. Pulmonary function, maximal inspiratory (P(insp)) and expiratory pressures (P(exp)), respiratory endurance (RET), and surface and underwater (4 fsw) fin swimming endurance were determined prior to and after RRMT, and monthly for 3 months. Pulmonary function did not significantly improve after either RRMT-3 or RMMT-5; while P(insp) (20 and 15%) and P(exp) (25 and 11%), RET (73 and 217%), surface (50 and 33%) and underwater (88 and 66%) swim times improved. VO2, VE and breathing frequency decreased during the underwater endurance swims after both RRMT-3 and RRMT-5. During RRMT-M P(insp) and P(exp) and RET and swimming times were maintained at post RRMT-3 levels. RRMT 3 or 5 days per week can be recommended to divers to improve both respiratory and fin swimming endurance, effects which can be maintained with RRMT twice weekly.
Article
We examined whether inspiratory muscle training (IMT) improved cycling time-trial performance and changed the relationship between limit work (W lim) and limit time (T lim), which is described by the parameters critical power (CP) and anaerobic work capacity (AWC). Eighteen male cyclists were assigned to either a pressure-threshold IMT or sham hypoxic-training placebo (PLC) group. Prior to and following a 6 week intervention subjects completed a 25-km cycling time-trial and three constant-power tests to establish the W lim–T lim relationship. Constant-power tests were prescribed to elicit exercise intolerance within 3–10 (Ex1), 10–20 (Ex2), and 20–30 (Ex3) min. Maximal inspiratory mouth pressure increased by (mean ± SD) 17.1 ± 12.2% following IMT (P < 0.01) and was accompanied by a 2.66 ± 2.51% improvement in 25-km time-trial performance (P < 0.05); there were no changes following PLC. Constant-power cycling endurance was unchanged following PLC, as was CP (pre vs. post: 249 ± 32 vs. 250 ± 32 W) and AWC (30.7 ± 12.7 vs. 30.1 ± 12.5 kJ). Following IMT Ex1 and Ex3 cycling endurance improved by 18.3 ± 15.1 and 15.3 ± 19.1% (P < 0.05), respectively, CP was unchanged (264 ± 62 vs. 263 ± 61 W), but AWC increased from 24.8 ± 5.6 to 29.0 ± 8.4 kJ (P < 0.05). In conclusion, these data provide novel evidence that improvements in constant-power and cycling time-trial performance following IMT in cyclists may be explained, in part, by an increase in AWC.
Article
This study investigated the effects of training with voluntary hypoventilation (VH) at low pulmonary volumes. Two groups of moderately trained runners, one using hypoventilation (HYPO, n=7) and one control group (CONT, n=8), were constituted. The training consisted in performing 12 sessions of 55 min within 4 weeks. In each session, HYPO ran 24 min at 70% of maximal O(2) consumption ( [V(02max)) with a breath holding at functional residual capacity whereas CONT breathed normally. A V(02max) and a time to exhaustion test (TE) were performed before (PRE) and after (POST) the training period. There was no change in V(O2max), lactate threshold or TE in both groups at POST vs. PRE. At maximal exercise, blood lactate concentration was lower in CONT after the training period and remained unchanged in HYPO. At 90% of maximal heart rate, in HYPO only, both pH (7.36+/-0.04 vs. 7.33+/-0.06; p<0.05) and bicarbonate concentration (20.4+/-2.9 mmolL(-1) vs. 19.4+/-3.5; p<0.05) were higher at POST vs. PRE. The results of this study demonstrate that VH training did not improve endurance performance but could modify the glycolytic metabolism. The reduced exercise-induced blood acidosis in HYPO could be due to an improvement in muscle buffer capacity. This phenomenon may have a significant positive impact on anaerobic performance.
Inspiratory muscle training improves lung function and exercise capacity in healthy subjects
  • S Enright
  • C Heward
  • L Withnall
  • D H Davies
  • V B Unnithan
Enright S, Heward C, Withnall L, Davies DH, Unnithan VB. Inspiratory muscle training improves lung function and exercise capacity in healthy subjects. Phy Ther; 2006; 86(3):345-354.
Front crawl kinematic: breathing and pace acute effect
  • F Castro
  • A C Guimaraes
Castro F, Guimaraes AC. Front crawl kinematic: breathing and pace acute effect. Portugese Journal of Sport Science, 2006; 6 (2); 26-28.