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The Effects of Hypercapnic-Hypoxic Training on Strength Respiratory Muscles and Swimming Performance of Elite Swimmers
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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Ten competitive, national level adult swimmers (age 25 ± 3 years (mean ± SD) swam three 25m freestyle sprints with different breathing patterns in randomised order to examine how breathing actions influence velocity during a 25m front crawl sprint. Velocity measurements were carried out using a computerized swimming speedometer and data from mid-pool free swimming (10-20m) was extracted. There was no significant difference in mean (±SD) velocity (v) between sprinting with one breath (v=1.74±0.14 m·s-1) compared to no breath (v=1.73±0.14 m·s-1). There was a significant (p<0.05) reduction in velocity when breathing every stroke cycle (v=1.70±0.14 m·s-1), compared to both no breath and one breath trials. Swimmers should breathe as little as possible during 50m freestyle races and breathe no more than every 3rd stroke cycle during a 100m freestyle race. Pedersen, T. and Kjendlie, P.-L. (2006). The effect of the breathing action on velocity in front crawl swimming.
The aim of this research was to establish the effects of the 8-week hypercapnic-hypoxic training program on hemoglobin concentration (Hb) and the maximum oxygen uptake (VO2max) in swimmers. The research was conducted on a sample of 16 Croatian elite male swimmers (experimental group n=8, control group n=8). Both groups were subjected to the same swimming trainings and additional training sessions on a treadmill. The experimental group was subjected additionally to hypercapnic-hypoxic training program with enhanced muscular activity. The experiment lasted for eight weeks. The following variables were used: hemoglobin concentration (Hb) and maximum oxygen uptake (VO2max). The ANOVA series application for the repeated measurements have shown significant Hb and VO2max concentration differences related to the effect of both
groups. The hypercapnic-hypoxic training method, which was applied to elite swimmers, has resulted in a 5.35% higher Hb concentration at the end of the program, which also caused a 10.79% increase in the VO2max.
Keywords
hypercapnic-hypoxic training; hemoglobin concentration; maximum oxygen uptake; swimmers
The purpose of the study was to investigate the influence of training with reduced breathing frequency (RBF) on tidal volume during incremental exercise where breathing frequency was restricted and on ventilatory response during exercise when breathing a 3% CO2 mixture. Twelve male participants were divided into two groups: experimental (Group E) and control (Group C). Both groups participated three cycle ergometry interval training sessions per week for six weeks. Group E performed it with RBF i.e. 10 breaths per minute and group C with spontaneous breathing. After training Group E showed a higher vital capacity (+8 ± 8%; p = 0.02) and lower ventilatory response during exercise when breathing a 3% CO2 mixture (-45 ± 27%; p = 0.03) compared with pre-training. These parameters were unchanged in Group C. Post-training peak power output with RBF (PPORBF) was increased in both groups. The improvement was greater in Group E (+42 ± 11%; p < 0.01) than in Group C (+11 ± 9%; p = 0.03). Tidal volume at PPORBF was higher post-training in Group E (+41 ± 19%; p = 0.01). The results of the present study indicate that RBF training during cycle ergometry exercise increased tidal volume during incremental exercise where breathing frequency was restricted and decreased ventilatory sensitivity during exercise when breathing a 3% CO2 mixture. Key PointsTraining with a reduced breathing frequency during exercise decreased ventilator sensitivity to carbon dioxide. In addition, it increased minute ventilation during exercise with imposed reduced breathing frequency.Training with reduced breathing frequency could not be realized at higher intensity of exercise due to the additional stress caused by such a breathing pattern. Therefore the improvement in aerobic endurance (considering peak oxygen uptake) could not be expected after this kind of training.
The aim of the study was to ascertain how four weeks of training with reduced breathing frequency during front crawl swimming would influence a maximal 200 meters front crawl performance. Two matched groups of five recreational-level swimmers trained 5 times per week. During each swimming session breathing frequency was distinguished between the control (the B2 group was taking a breath every second stroke cycle) and an experimental (the B4 group was taking a breath every fourth stroke cycle). The swimmers performed a maximal 200 meters front crawl swim with an optional breathing pattern before and after the training. Both groups swam the maximal 200 meters front crawl after the training significantly faster then before the training. This improvement was significantly greater in the B4 group than the B2 group. B4 group swam the maximal 200 meters front crawl after the training with fewer breaths than before the training. The breathing pattern in the B2 group was unchanged by the training. According to its lower breathing frequency the B4 group had significantly higher Pco2 after the training in comparison with Pco2 before the training. The B4 group also had higher lactate concentration, Pco2 and a lower pH than the B2 group after the training. It may be concluded that swimmers adapted to swim with fewer breaths due to training with reduced breathing frequency (taking a breath every fourth stroke cycle) during front crawl swimming.
The purpose of this study was to assess the influence of the work history of the inspiratory
muscles upon the fatigue characteristics of the plantar flexors (PF).We hypothesized that under
conditions where the inspiratory muscle metaboreflex has been elicited, PF fatigue would be
hastened due to peripheral vasoconstriction. Eight volunteers undertook seven test conditions,
two ofwhichfollowed4 week of inspiratorymuscle training(IMT). The inspiratorymetaboreflex
was induced by inspiring against a calibrated flowresistor.We measured torque andEMGduring
isometric PF exercise at 85% of maximal voluntary contraction (MVC) torque. Supramaximal
twitches were superimposed uponMVC efforts at 1 min intervals (MVCTI); twitch interpolation
assessed the level of central activation. PF was terminated (Tlim) when MVCTI was<50% of
baseline MVC. PF Tlim was significantly shorter than control (9.93±1.95 min) in the presence
of a leg cuff inflated to 140 mmHg(4.89±1.78 min; P =0.006), as well aswhen PF was preceded
immediately by fatiguing inspiratory muscle work (6.28±2.24 min; P =0.009). Resting the
inspiratory muscles for 30 min restored the PF Tlim to control. After 4 weeks, IMT, inspiratory
muscle work at the same absolute intensity did not influence PF Tlim, but Tlim was significantly
shorter at thesamerelative intensity.Thedata are the first toprovide evidence that the inspiratory
muscle metaboreflex accelerates the rate of calf fatigue during PF, and that IMT attenuates this
effect.
We aimed to characterize the cardiovascular, lactate and perceived exertion responses in relation to performance during competition in junior and senior elite synchronized swimmers.
34 high level senior (21.4±3.6 years) and junior (15.9±1.0) synchronized swimmers were monitored while performing a total of 96 routines during an official national championship in the technical and free solo, duet and team competitive programs. Heart rate was continuously monitored. Peak blood lactate was obtained from serial capillary samples during recovery. Post-exercise rate of perceived exertion was assessed using the Borg CR-10 scale. Total competition scores were obtained from official records.
Data collection was complete in 54 cases. Pre-exercise mean heart rate (beats·min(-1)) was 129.1±13.1, and quickly increased during the exercise to attain mean peak values of 191.7±8.7, with interspersed bradycardic events down to 88.8±28.5. Mean peak blood lactate (mmol·L(-1)) was highest in the free solo (8.5±1.8) and free duet (7.6±1.8) and lowest at the free team (6.2±1.9). Mean RPE (0-10+) was higher in juniors (7.8±0.9) than in seniors (7.1±1.4). Multivariate analysis revealed that heart rate before and minimum heart rate during the routine predicted 26% of variability in final total score.
Cardiovascular responses during competition are characterized by intense anticipatory pre-activation and rapidly developing tachycardia up to maximal levels with interspersed periods of marked bradycardia during the exercise bouts performed in apnea. Moderate blood lactate accumulation suggests an adaptive metabolic response as a result of the specific training adaptations attributed to influence of the diving response in synchronized swimmers. Competitive routines are perceived as very to extremely intense, particularly in the free solo and duets. The magnitude of anticipatory heart rate activation and bradycardic response appear to be related to performance variability.
Recently, we have shown that an untrained respiratory system does limit the endurance of submaximal exercise (64% peak oxygen consumption) in normal sedentary subjects. These subjects were able to increase breathing endurance by almost 300% and cycle endurance by 50% after isolated respiratory training. The aim of the present study was to find out if normal, endurance trained subjects would also benefit from respiratory training. Breathing and cycle endurance as well as maximal oxygen consumption (
[(V)\dot]O2 max\dot VO_{2 max}
) and anaerobic threshold were measured in eight subjects. Subsequently, the subjects trained their respiratory muscles for 4 weeks by breathing 85-1601 min–1 for 30 min daily. Otherwise they continued their habitual endurance training. After respiratory training, the performance tests made at the beginning of the study were repeated. Respiratory training increased breathing endurance from 6.1 (SD 1.8) min to about 40 min. Cycle endurance at the anaerobic threshold [77 (SD 6) %
[(V)\dot]O2 max\dot VO_{2 max}
] was improved from 22.8 (SD 8.3) min to 31.5 (SD 12.6) min while
[(V)\dot]O2 max\dot VO_{2 max}
and the anaerobic threshold remained essentially the same. Therefore, the endurance of respiratory muscles can be improved remarkably even in trained subjects. Respiratory muscle fatigue induced hyperventilation which limited cycle performance at the anaerobic threshold. After respiratory training, minute ventilation for a given exercise intensity was reduced and cycle performance at the anaerobic threshold was prolonged. These results would indicate the respiratory system to be an exercise limiting factor in normal, endurance trained subjects.
This study aimed to determine the cardiovascular responses during a prolonged exercise with voluntary hypoventilation (VH). 7 men performed 3 series of 5-min exercise at 65% of normoxic maximal O (2) uptake under 3 conditions: (1) normal breathing (NB) in normoxia (NB (0.21)), (2) VH in normoxia (VH (0.21)), (3) NB in hypoxia (NB (0.157), inspired oxygen fraction=0.157). In both VH (0.21) and NB (0.157), there was a similar drop in arterial oxygen saturation and arterial O (2) content (CaO (2)) which were lower than in NB (0.21). Heart rate (HR), stroke volume, and cardiac output (-) were higher in VH (0.21) than in NB (0.21) during most parts of exercise whereas there was no difference between NB (0.157) and VH (0.21) or NB (0.21). HR variability analysis suggested an increased sympathetic modulation in VH (0.21) only. O (2) transport and oxygen uptake were generally not different between interventions. Mixed venous O (2) content (C-O (2)) was lower in NB (0.157) than in both VH (0.21) and NB (0.21) and not different between the latter. CaO (2)-C-O (2) was not different between NB (0.157) and NB (0.21) but lower in VH (0.21). This study shows that a prolonged exercise with VH leads to a greater cardiac activity, independent from the hypoxic effect. The greater - in VH compared to normal breathing seems to be the main factor for compensating the drop of arterial oxygen content.
Measurement of the maximal inspiratory mouth pressure (PImax) is a simple, reproducible, and non-invasive method frequently used for estimation of the inspiratory muscle strength. The aim of the study was to assess the PImax values in well-trained representatives of the endurance sports and to determine the basic relationships between these values and age, training experience, somatic indices and aerobic capacity of the tested subjects. Overall, thirty female and thirty-five male elite junior and senior representatives of the endurance sports were included in the investigation. PImax and maximal oxygen uptake (VO2max) were estimated in all the subjects. In the female athletes the obtained mean PImax values (118±24 cm H2O) were significantly lower than the respective values estimated in their male counterparts (143±25 cm H2O). Of all the tested relationships significant correlation was detected only between PImax and VO2max in the females (r=0.475) and only between PImax and the body mass index (BMI) in the males (r=0.501). Since the published values of PImax vary greatly depending, among other factors, on the studied population, methods and techniques of the measurement and motivation of the tested subjects it is suggested that each laboratory elaborate its own reference values. The results indicate that in the female and in the male athletes the inspiratory muscle strength is not related to the body size. On the other hand, the detected correlation between PImax and BMI in the males may suggest a possible relationship between the inspiratory muscle strength and the total muscle mass. Presumably, endurance training in the well-trained individuals can not enhance any more the inspiratory muscle strength or the described relationships are indirect and depend on the intersexual differences.
Objectives: This study was designed to investigate whether reduced breathing frequency during moderate intensity exercise produces similar metabolic responses as during exercise with spontaneous breathing at higher absolute intensity.Methods: Eight healthy male subjects performed a constant load test with reduced breathing frequency at 10 breaths per minute to exhaustion (B10) at the peak power output obtained during the incremental test with RBF (peak power output increased every two minutes for 30 W). The subjects then performed a constant load test with the spontaneous breathing to exhaustion (SB) at peak power output obtained during the incremental test with spontaneous breathing. Results: Respiratory parameters (VE, PETO2, PETCO2), metabolic parameters (Vo2, Vco2) and oxygen saturation (SaO2) were measured during both constant load tests. Capillary blood samples were taken before and every minute during both constant load tests in order to measure lactate concentration ([LA-]) and parameters of capillary blood gases and acid base status (Po2, Pco2, pH). Regardless of the type of comparison (the data obtained at the defined time or maximum and minimum values during the exercise), there were significant differences between SB and B10 in all respiratory parameters, metabolic parameters and SaO2 (p ≤ 0.01 and 0.05). There were significantly lower [LA-] and Pco2 during B10, when compared to SB (p≤0.01). However, there were no significant differences in pH during the exercise between different breathing conditions. Conclusion: It can be concluded that reduced breathing frequency during exercise at lower absolute intensity did not produce similar conditions as during the exercise with spontaneous breathing at higher absolute intensity.
Eight men performed three series of 5-min exercise on a cycle ergometer at 65% of normoxic maximal O(2) consumption in four conditions: (1) voluntary hypoventilation (VH) in normoxia (VH(0.21)), (2) VH in hyperoxia (inducing hypercapnia) (inspired oxygen fraction [F(I)O(2)] = 0.29; VH(0.29)), (3) normal breathing (NB) in hypoxia (F(I)O(2) = 0.157; NB(0.157)), (4) NB in normoxia (NB(0.21)). Using near-infrared spectroscopy, changes in concentration of oxy-(Delta[O(2)Hb]) and deoxyhemoglobin (Delta[HHb]) were measured in the vastus lateralis muscle. Delta[O(2)Hb - HHb] and Delta[O(2)Hb + HHb] were calculated and used as oxygenation index and change in regional blood volume, respectively. Earlobe blood samples were taken throughout the exercise. Both VH(0.21) and NB(0.157) induced a severe and similar hypoxemia (arterial oxygen saturation [SaO(2)] < 88%) whereas SaO(2) remained above 94% and was not different between VH(0.29) and NB(0.21). Arterialized O(2) and CO(2) pressures as well as P50 were higher and pH lower in VH(0.21) than in NB(0.157), and in VH(0.29) than in NB(0.21). Delta[O(2)Hb] and Delta[O(2)Hb - HHb] were lower and Delta[HHb] higher at the end of each series in both VH(0.21) and NB(0.157) than in NB(0.21) and VH(0.29). There was no difference in Delta[O(2)Hb + HHb] between testing conditions. [La] in VH(0.21) was greater than both in NB(0.21) and VH(0.29) but not different from NB(0.157). This study demonstrated that exercise with VH induced a lower tissue oxygenation and a higher [La] than exercise with NB. This was caused by a severe arterial O(2) desaturation induced by both hypoxic and hypercapnic effects.
Apnea divers are exposed to repeated massive arterial oxygen desaturation, which could perturb chemoreflexes. An earlier study suggested that peripheral chemoreflex regulation of sympathetic vasomotor tone and ventilation may have recovered 4 or more weeks into the off season. Therefore, we tested the hypothesis that peripheral chemoreflex regulation of ventilation and sympathetic vasomotor tone is present during the training season. We determined ventilation, heart rate, blood pressure, cardiac stroke volume, and muscle sympathetic nerve activity (MSNA) during isocapnic hypoxia in 10 breath hold divers and 11 matched control subjects. The study was carried out at the end of the season of intense apnea trainings. Baseline MSNA frequency was 30+/-4bursts/min in control subjects and 25+/-4bursts/min in breath hold divers (P=0.053). During hypoxia burst frequency and total sympathetic activity increased similarly in both groups. Sympathetic activity normalized during the 30-minute recovery. Hypoxia-induced stimulation of minute ventilation was similar in both groups, although in divers it was maintained by higher tidal volumes and lower breathing frequency compared with control subjects. In both groups, hypoxia increased heart rate and cardiac output whereas total peripheral resistance decreased. Blood pressure remained unchanged. We conclude that peripheral chemoreflex regulation of ventilation and sympathetic vasomotor tone is paradoxically preserved in apnea divers, both, during the off and during the training season. The observation suggests that repeated arterial oxygen desaturation may not be sufficient explaining sympathetic reflex abnormalities similar to those in obstructive sleep apnea patients.
The physiological responses to apnea training exhibited by elite breath-hold divers may contribute to improving sports performance. Breath-hold divers have shown reduced blood acidosis, oxidative stress and basal metabolic rate, and increased hematocrit, erythropoietin concentration, hemoglobin mass and lung volumes. We hypothesise that these adaptations contributed to long apnea durations and improve performance. These results suggest that apnea training may be an effective alternative to hypobaric or normobaric hypoxia to increase aerobic and/or anaerobic performance.
Cet article de synthese fait le point sur les resultats de la recherche concernant les effets d'un entrainement de natation sur la structure et les fonctions pulmonaires et sur les mecanismes d'action responsable de l'adaptation pulmonaire a l'entrainement intensif de natation en faisant le tour des contraintes particulieres appliquees au systeme pulmonaire chez les nageurs
In an effort to determine the role played by power in sprint swimming, 40 competitive swimmers (22 females and 18 males) were tested for arm power at velocities ranging from 1.60-3.28 m . s-1 using an apparatus that was specifically designed to mimic the arm action during swimming. Measurements were also made to determine the contribution of fatigability to spring swimming performance. In addition, each swimmer performed a series of 25-yd (22.86 m) freestyle sprints. A close relationship was found between power output and sprint swimming performance (r = 0.90). The highest power recordings were obtained at test velocities of 2.05 and 2.66 m . s-1, with the average velocity required for peak power being 2.40 m . s-1. This point is referred to as the optimal velocity. Four detrained swimmers were tested before and after 4 wk of isokinetic strength training only. On the average, performance improved 3.76%, while arm power increased by 18.66%. The fatigability of the competitive swimmers was not related to their sprint ability (r = 0.01). It is concluded that power, as measured in this study, offers an objective assessment of a component essential for success in sprint swimming.
Twelve subjects without and ten subjects with diving experience performed short diving-related interventions. After labeling of erythrocytes, scintigraphic measurements were continuously performed during these interventions. All interventions elicited a graduated and reproducible splenic contraction, depending on the type, severity, and duration of the interventions. The splenic contraction varied between approximately 10% for "apnea" (breath holding for 30 s) and "cold clothes" (cold and wet clothes applied on the face with no breath holding for 30 s) and approximately 30-40% for "simulated diving" (simulated breath-hold diving for 30 s), "maximal apnea" (breath holding for maximal duration), and "maximal simulated diving" (simulated breath-hold diving for maximal duration). The strongest interventions (simulated diving, maximal apnea, and maximal simulated diving) elicited modest but significant increases in hemoglobin concentration (0.1-0.3 mmol/l) and hematocrit (0.3-1%). By an indirect method, the splenic venous hematocrit was calculated to 79%. No major differences were observed between the two groups. The splenic contraction should, therefore, be included in the diving response on equal terms with bradycardia, decreased peripheral blood flow, and increased blood pressure.
We hypothesized that the repetition of brief epochs of hypoxemia in elite human breath-hold divers could induce an adaptation of their metabolic responses, resulting in reduced blood acidosis and oxidative stress. Trained divers who had a 7-10 year experience in breath-hold diving, and were able to sustain apnea up to 440 sec at rest, were compared to control individuals who sustained apnea for 145 sec at the most. The subjects sustained apnea at rest (static apnea), and then, performed two 1-min dynamic forearm exercises whether they breathed (control exercise) or sustained apnea (dynamic apnea). We measured arterial blood gases, venous blood pH, and venous blood concentrations of lactic acid, thiobarbituric acid reactive substances (TBARS), and two endogenous anti-oxidants (reduced glutathione, GSH, and reduced ascorbic acid, RAA). In control subjects, the three experimental conditions elicited an increase in blood lactic acid concentration and an oxidative stress (increased TBARS, decreased GSH and RAA concentrations). In divers, the changes in lactic acid, TBARS, RAA, and GSH concentrations were markedly reduced after static and dynamic apnea, as well as after control exercise. Thus, human subjects involved in a long duration training programme of breath-hold diving have reduced post-apnea as well as post-exercise blood acidosis and oxidative stress, mimicking the responses of diving animals.
The purpose of this study was 1) to answer whether the reduction in spleen size in breath-hold apnea is an active contraction or a passive collapse secondary to reduced splenic arterial blood flow and 2) to monitor the spleen response to repeated breath-hold apneas. Ten trained apnea divers and 10 intact and 7 splenectomized untrained persons repeated five maximal apneas (A1-A5) with face immersion in cold water, with 2 min interposed between successive attempts. Ultrasonic monitoring of the spleen and noninvasive cardiopulmonary measurements were performed before, between apneas, and at times 0, 10, 20, 40, and 60 min after the last apnea. Blood flows in splenic artery and splenic vein were not significantly affected by breath-hold apnea. The duration of apneas peaked after A3 (143, 127, and 74 s in apnea divers, intact, and splenectomized persons, respectively). A rapid decrease in spleen volume ( approximately 20% in both apnea divers and intact persons) was mainly completed throughout the first apnea. The spleen did not recover in size between apneas and only partly recovered 60 min after A5. The well-known physiological responses to apnea diving, i.e., bradycardia and increased blood pressure, were observed in A1 and remained unchanged throughout the following apneas. These results show rapid, probably active contraction of the spleen in response to breath-hold apnea in humans. Rapid spleen contraction and its slow recovery may contribute to prolongation of successive, briefly repeated apnea attempts.
Specific respiratory muscle training offers the promise of improved exercise tolerance and athletic performance for a wide range of users. However, the literature addressing respiratory muscle training in healthy people remains controversial. Studies into the effect of respiratory muscle training upon whole body exercise performance have used at least one of the following modes of training: voluntary isocapnic hyperpnea, flow resistive loading, and pressure threshold loading. Each of these training modes has the potential to improve specific aspects of respiratory muscle function. Some studies have demonstrated significant improvements in either time to exhaustion or time trial performance, whilst others have demonstrated no effect. We present an overview of the literature that rationalizes its contradictory findings. Retrospective analysis of the literature suggests that methodological factors have played a crucial role in the outcome of respiratory muscle training studies. We conclude that in most well controlled and rigorously designed studies, utilizing appropriate outcome measures, respiratory muscle training has a positive influence upon exercise performance. The mechanisms by which respiratory muscle training improves exercise performance are unclear. Putative mechanisms include a delay of respiratory muscle fatigue, a redistribution of blood flow from respiratory to locomotor muscles, and a decrease in the perceptions of respiratory and limb discomfort.
The monocarboxylate transporter MCT4 mediates lactic acid efflux from most tissues that are dependent on glycolysis for their ATP production. Here we demonstrate that expression of MCT4 mRNA and protein was increased >3-fold by a 48-h exposure to 1% O(2), whereas MCT1 expression was not increased. The effect was mimicked by CoCl(2) (50 microm), suggesting transcriptional regulation by hypoxia-inducible factor 1alpha (HIF-1alpha). The predicted promoters for human MCT1, MCT2, and MCT4 were cloned into the pGL3 vector and shown to be active (luciferase luminescence) under basal conditions. Only the MCT4 promoter was activated (>2-fold) by hypoxia. No response was found in cells lacking HIF-1alpha. Four potential hypoxia-response elements were identified, but deletion analysis implicated only two in the hypoxia response. These were just upstream from the transcription start site and also found in the mouse MCT4 promoter. Mutation of site 2 totally abolished the hypoxic response, whereas mutation of site 1 only reduced the response. Gel-shift analysis demonstrated that nuclear extracts of hypoxic but not normoxic HeLa cells contained two transcription factors that bound to DNA probes containing these hypoxia-response elements. The major shifted band was abolished by mutation of site 2, and supershift analysis confirmed that HIF-1alpha bound to this site. Binding of the second factor was abolished by mutation of site 1. We conclude that MCT4, like other glycolytic enzymes, is up-regulated by hypoxia through a HIF-1alpha-mediated mechanism. This adaptive response allows the increased lactic acid produced during hypoxia to be rapidly lost from the cell.
We investigated the effect of 4 week of inspiratory (IMT) or expiratory muscle training (EMT), as well as the effect of a subsequent 6 week period of combined IMT/EMT on rowing performance in club-level oarsmen. Seventeen male rowers were allocated to either an IMT (n = 10) or EMT (n = 7) group. The groups underwent a 4 week IMT or EMT program; after interim testing, both groups subsequently performed a 6 week program of combined IMT/EMT. Exercise performance and physiological responses to exercise were measured at 4 and 10 week during an incremental rowing ergometer ‘step-test’ and a 6 min all-out (6MAO) effort. Pressure threshold respiratory muscle training was undertaken at the 30 repetition maximum load (∼50% of the peak inspiratory and expiratory mouth pressure, P
Imax or P
Emax, respectively). P
Imax increased during the IMT phase of the training in the IMT group (26%, P < 0.001) and was accompanied by an improvement in mean power during the 6MAO (2.7%, P = 0.015). Despite an increase in P
Emax by the end of the intervention (31%, P = 0.03), the EMT group showed no significant changes in any performance parameters during either the ‘step-test’ or 6MAO. There were no significant changes in breathing pattern or the metabolic response to the 6MAO test in either group, but the IMT group showed a small decrease in HR (2–5%, P = 0.001). We conclude that there were no significant additional changes following combined IMT/EMT. IMT improved rowing performance, but EMT and subsequent combined IMT/EMT did not.
In diving mammals splenic contraction increases circulating red cell volume, whereas in humans increased haemoglobin concentrations have been reported. It is unknown, however, whether repetitive apnea diving also comprises an adaptive increase in total red cell volume as reported in endurance athletes. The first aim of the study therefore was to investigate the effect of repeated apnea dives on splenic size and putative red cell release in trained apnea divers (n = 10) and control subjects (SCUBA divers performing apneas without long-term apnea training, n = 7). Long-term effects of repetitive apnea diving may elevate the oxygen transport capacity by an adaptive increase in total haemoglobin mass as reported in endurance athletes. The second goal, therefore, was to compare the trained apnea divers' and the control divers' total haemoglobin mass (tHb-mass) with that of endurance-trained (n = 9) and untrained (n = 10) non-divers. Before and immediately after a series of five dives to a depth of 4 m in a heated pool, spleen volume was assessed with ultrasound tomography. tHb-mass and plasma volume were measured using the CO-rebreathing method. In the trained apnea divers, repeated apnea dives resulted in a 25% reduction of spleen size (P < 0.001), whereas no significant effect was observed in the control subjects. While tHb-mass did not differ between trained apnea divers, untrained SCUBA divers performing apneas and untrained non-divers, it was 30% lower than in endurance-trained non-divers. We conclude that prolonged apnea training causes marked apnea-induced splenic contraction. In contrast to athletes in endurance sports, the trained apnea divers did not present with increased total haemoglobin mass and, hence, no increase in blood oxygen stores.
This study analyzed kinematic changes during a 100-m front crawl to investigate the effects of performance level and gender, comparing 12 high-speed males, 8 medium-speed males, 8 low-speed males, and 8 high-speed females.
Assessments were made throughout the race in a 25-m pool divided into five zones of 5 m. Velocity (V), stroke rate (SR), and stroke length (SL) were calculated for each 25-m length (L1 to L4) and for each 5-m zone. Four stroke phases were identified by video analysis, and the index of coordination (IdC) was calculated. Three modes of arm coordination were identified: catch-up, opposition, and superposition. The leg kick was also analyzed.
The high-speed male swimmers were distinguished by higher V (1.89 m.s(-1)), SR (0.78 Hz), SL (2.16 m per stroke), propulsive phase (54%), and IdC (3.8%) (P < 0.05), and by the stability of these values throughout the race. The medium- and low-speed males had an opposition coordination (-1% < IdC < 1%) during the third length of the 100 m. Because of fatigue in length 4, they spent more time with the hand in the push phase (possibly because of a decrease in hand velocity) and changed to superposition coordination (medium-speed males: IdC = 2.78%; low-speed males: IdC = 1.12%) (P < 0.05). This change was ineffective, however, as SL continued to decrease throughout the 100 m (P < 0.05). The main gender findings were the greater SL of the males versus the females (1.81 m per stroke) (P < 0.05) and the similar IdC of both high-speed groups (females: 4.4%).
The high-speed swimmers were characterized by higher and more stable SL and IdC. The principal gender effect was greater SL in the males than in the females.
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.
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%).
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.
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.
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.
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
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.
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.
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.
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)
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.
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.
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.
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.
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.
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.
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.
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).
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.
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.
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.