Four-week experimental plus 1-week taper period using live high train low does not alter muscle glycogen content

This study aimed to investigate the effects of a 4-week live high train low (LHTL; FiO2 ~ 13.5%), intervention, followed by a tapering phase, on muscle glycogen concentration. Fourteen physically active males (28 ± 6 years, 81.6 ± 15.4 kg, 179 ± 5.2 cm) were divided into a control group (CON; n = 5), and the group that performed the LHTL, which was exposed to hypoxia (LHTL; n = 9). The subjects trained using a one-legged knee extension exercise, which enabled four experimental conditions: leg training in hypoxia (TLHYP); leg control in hypoxia (CLHYP, n = 9); leg trained in normoxia (TLNOR, n = 5), and leg control in normoxia (CLNOR, n = 5). All participants performed 18 training sessions lasting between 20 and 45 min [80-200% of intensity corresponding to the time to exhaustion (TTE) reached in the graded exercise test]. Additionally, participants spent approximately 10 h day-1 in either a normobaric hypoxic environment (14.5% FiO2; ~ 3000 m) or a control condition (i.e., staying in similar tents on ~ 530 m). Thereafter, participants underwent a taper protocol consisting of six additional training sessions with a reduced training load. SpO2 was lower, and the hypoxic dose was higher in LHTL compared to CON (p < 0.001). After 4 weeks, glycogen had increased significantly only in the TLNOR and TLHYP groups and remained elevated after the taper (p < 0.016). Time to exhaustion in the LHTL increased after both the 4-week training period and the taper compared to the baseline (p < 0.001). Although the 4-week training promoted substantial increases in muscle glycogen content, TTE increased in LHTL condition.

Acute and cumulative effects of hypoxia exposure in people with Parkinson's disease: A scoping review and evidence map

Hypoxia exposure may promote neuroprotection for people with Parkinson's disease (PwPD). However, to implement hypoxia in practical settings and direct future research, it is necessary to organize the current knowledge about hypoxia responses/effects in PwPD. Thus, the present scoping review elucidates the evidence about hypoxia exposure applied to PwPD. Following the PRISMA Extension for Scoping Reviews, papers were searched in PubMed/NCBI, Web of Science, and Scopus (descriptors: Parkinson and hypoxia, mountain, or altitude). We included original articles published in English until August 12, 2023. Eight studies enrolled participants with early to moderate stages of disease. Acute responses demonstrated that PwPD exposed to normobaric hypoxia presented lower hypoxia ventilatory responses (HVR), perceptions of dyspnea, and sympathetic activations. Cumulative exposure to hypobaric hypoxia (living high; 7 days; altitude not reported) induced positive effects on motor symptoms (hypokinesia) and perceptions of PwPD (quality of life and living with illness). Normobaric hypoxia (isocapnic rebreathe, 14 days, three times/day of 5-7 min at 8-10 % of O2) improved HVR. The included studies reported no harmful effects. Although these results demonstrate the effectiveness and safety of hypoxia exposure applied to PwPD, we also discuss the methodological limitations of the selected experimental design (no randomized controlled trials), the characterization of the hypoxia doses, and the range of symptoms investigated. Thus, despite the safety of both normobaric hypoxia and hypobaric hypoxia for early to moderate levels of disease, the current literature is still incipient, limiting the use of hypoxia exposure in practical settings.

Recovery of kicking kinematics and performance following repeated high-intensity running bouts in the heat: Can a rapid local cooling intervention help young soccer players?

The effects of a cooling strategy following repeated high-intensity running (RHIR) on soccer kicking performance in a hot environment (>30ºC) were investigated in youth soccer players. Fifteen academy under-17 players participated. In Experiment 1, players completed an all-out RHIR protocol (10×30 m, with 30s intervals). In Experiment 2 (cross-over design), participants performed this running protocol under two conditions: (1) following RHIR 5 minutes of cooling where ice packs were applied to the quadriceps/hamstrings, (2) a control condition involving passive resting. Perceptual measures [ratings of perceived exertion (RPE), pain and recovery], thigh temperature and kick-derived video three-dimensional kinematics (lower limb) and performance (ball speed and two-dimensional placement indices) were collected at baseline, post-exercise and intervention. In Experiment 1, RHIR led to small-to-large impairments (p < 0.03;d = -0.42--1.83) across perceptual, kinematic and performance measures. In experiment 2, RPE (p < 0.01; Kendall's W = 0.30) and mean radial error (p = 0.057; η² = 0.234) increased only post-control. Significant small declines in ball speed were also observed post-control (p < 0.05; d = 0.35). Post-intervention foot centre-of-mass velocity was moderately faster in the cooling compared to control condition (p = 0.04; d = 0.60). In youth soccer players, a short cooling period was beneficial in counteracting declines in kicking performance, in particular ball placement, following intense running activity in the heat.

Two Different Approaches to Dry-land Training Do Not Improve the Water Performance of Swimmers

Literature diverges about the performance improvement after dry-land training. Thus, the objective of the present study was to compare the effect of two models of dry-land training. Twenty-nine swimmers were divided into three groups, combined strength and power training (PTG), only strength training (STG), and a control group (CG). Measurements were taken for six weeks, before dry-land exposure (M1), after four weeks of specific training with exposure to dry-land training by two groups (M2), and after two weeks of taper without exposure to dry-land training (M3). Strength in specific exercises, jumping tests, and 50, 100, and 200m freestyle performance were evaluated on M1 and M3, while hematological and strength parameters in tethered swimming were measured in M1, M2, and M3. PTG showed time-effect improvement for 200, 100, and 50m performance (p<0.014), CG for 200 and 100m (p<0.047), and STG only for 100m (p:0.01). No differences were found in Δ performance between groups. PTG showed improvement in the peak force of tethered swimming on M2 (p:0.019), followed by a decrease on M3 (p:0.003). PTG and STG also showed an increase in creatinine, lactate dehydrogenase (LDH), and creatine kinase (CK) after M2 (p<0.038). Finally, it was concluded that both dry-land training sessions could change hematological parameters and improve physical attributes on dry-land and tethered swimming tests without improving performance.

Cardiopulmonary Exercise Testing with Elastic Resistance: A New Reproducible Proposal for Determination of Ventilatory Thresholds and Maximum Oxygen Consumption

To propose a new Cardiopulmonary Exercise Test with Elastic Resistance (CPxEL) and compare the physiological responses to conventional cardiopulmonary exercise test (CPx) performed on a treadmill. In addition, we tested the reproducibility of the CPxEL. Twenty-four physically active participants completed the CPx (first session) and CPxEL twice (second and third sessions) interspersed by seven days. A treadmill protocol with increments of 1km·h^-1 every minute until exhaustion was used in CPx. The CPxEL consisted of performing alternating steps back-and-forth against an elastic resistance attached to a belt and an incremental protocol with 1 stage (S) per minute following a cadence of 200 bpm controlled by a metronome in an 8-stage rubber mat. First analysis: first ventilatory threshold (VT1) occurred at 69.7% and 75.3% of maximal heart rate (HR_max) and 53.5% and 65.7% of maximal oxygen consumption (V̇O_2max). Second VT (VT2) occurred at 93.3% and 96.8% of the HR_max and 87.0% and 96.9% of V̇O_2max for CPx and CPxEL, respectively. At exhaustion, V̇O_2max, perceived exertion (BORG-CR10 and OMNI-RES EB), and test duration presented lower values for CPxEL (P < 0.05). Second analysis: VT1 occurred at warm-up (S0) (P = 0.731), VT2 occurred at S5 (P = 0.912), and the exhaustion occurred at S6 and S7 (P = 0.271) for CPxEL and retest, respectively. The intraclass correlation coefficient (ICC) for V̇O_2max was 0.921 and for HR_max was 0.930. The CPxEL has good test-retest reproducibility and represents a possible and interesting add-on to determine maximal oxygen consumption, maximal heart rate, and second ventilatory threshold without using traditional ergometers.

Anaerobic Contributions Are Influenced by Active Muscle Mass and The Applied Methodology in Well-Controlled Muscle Group

The anaerobic metabolism determination is complex and the applied methodologies present limitations. Thus, the purpose of this study was to investigate the effects of different calculations (MAOD vs. AOD) on the anaerobic contribution using the dynamic knee extension. Twenty-four male were recruited [Mean (SD); age 27 (1) years, body mass 90 (3) kg, height 181 (2) cm]. This study was divided into two independent experiments (EXP_1: one-legged; EXP₂: two-legged). In both experiments, it was performed a graded exercise test to determine maximal power (MP-GXT); 2-4 submaximal efforts (VO₂-intensity relationship); and an exhaustive effort. The theoretical energy demand for the exhaustive effort (TED_ex) was constructed from the submaximal efforts. Therefore, MAOD was assumed as the difference between the TED_ex and the accumulated VO₂ (AVO₂). In contrast, the energy demand for AOD was calculated as the product between VO₂ at the end of exercise and time to exhaustion (TED_aod). Thus, AOD was assumed as the difference between TED_aod and AVO₂. Bayesian paired t-test was used to compare the differences between the applied methods. Also, correlations between the anaerobic indices and performance were verified. In EXP₁, AOD was higher than MAOD [1855 (741) vs. 434 (245); BF₁₀ = 2925; ES = 2.5]. In contrast, in EXP₂, MAOD was higher than AOD [2832 (959) vs. 1636 (549); BF₁₀ = 3.33; ES = 1.4]. Also, AOD was correlated to performance (r = .59; BF₁₀ = 4.38). We concluded that MAOD and AOD are a distinct phenomenon and must be utilized according to the exercise model.

Lateral Preference and Inter-limb Asymmetry in Completing Technical Tasks During Official Professional Futsal Matches: The Role of Playing Position and Opponent Quality

This study had the purpose of analyzing dominant and non-dominant limb performances (frequency of use and accuracy) during match-play technical actions with ball possession (receiving, passing, and shooting a ball) in professional futsal and also check for the possible influence of playing position and the quality of opponent. We have analyzed data pertaining to eight matches of the FIFA Futsal World Cup Thailand 2012™ in which 76 male professional senior futsal players participated (44 right-footed and 32 left-footed). In total, we coded 5,856 actions (2,550 ball receptions, 3,076 passes, and 230 shoots). Our main findings were that (a) players used the dominant limb more frequently than the non-dominant limb for all actions considered [p < 0.001; effect size (ES) medium-to-large]; (b) accuracy was generally greater when using the dominant limb, regardless of the quality of opponent (p < 0.01; ES large); and (c) in shooting actions, pivots showed similar accuracy between dominant and non-dominant limbs (p = 0.51; ES small). The study suggested that when completing technical actions with the ball in futsal, high-level players depended to a greater extent on the use of their dominant lower limb during official matches. Excepting a similarity detected between limbs on shooting performance of pivots, players from all positional roles generally showed a higher accuracy rate in receiving, passing, and shooting a ball when using their dominant limb as compared to their non-dominant one during match-play and the limb usage and accuracy seemed to be independent of the quality of opponents.

Effects of an experimental taper period on male and female swimmers

BACKGROUND

This study investigated the possible influence of the gender on the responses of swimmers during a taper period (TP).

METHODS

Ten males (19 ± 3 years and 73.5 ± 7.8 kg) and ten females (17 ± 2 years and 54.7 ± 7.2 kg) swimmers were submitted to a 12-week training, followed by three weeks of the TP. Before and after the TP we evaluated the performance at 100 m freestyle, stroke parameters and lactacidemic responses; lactate minimum intensity (LMI) and stroke parameters associated with LMI and the propulsive force in tethered swimming. TP consisted of 14 sessions with mean volume 2,253 ± 1,213 m•session-1 at an intensity below than the LMI, 1,730 ± 327 m•session-1 at an intensity near the LMI and 1,530 ± 1,019 m•session-1 at an intensity above the LMI.

RESULTS

Significant effects of the genders were observed for LMI and stroke parameters (p-value < 0.001 and η2 > 0.52 [large]) and propulsive force (p-value = 0.001; η2 = 0.59 [large]). However, no significant effects of the TP were identified in the performance of the 100 m freestyle (p-value = 0.66; η2 = 0.006 [small]), propulsive force (p-value > 0.63; η2 < 0.006 [small]), aerobic parameters (LMI: p-value = 0.32 and η2 = 0.03 [small]) and mechanical parameters (p-value > 0.23; η2 = 0.01 [small]). Nonetheless, the peak blood lactate concentrations were improved after TP (p-value = 0.014; η2 = 0.16 [large]), without significant interactions (p-value = 0.38; η2 = 0.02 [small]), as well as the mechanical parameters during maximum 100 m freestyle (p-value < 0.04 and η2 > 0.10 [medium]).

CONCLUSIONS

Hence, men and women presenting significantly different values in the age group studied, the responses observed after the TP investigated were the same independent of gender.

Backward extrapolation technique: analysis of different criteria after supramaximal exercise in cycling

BACKGROUND

Backward extrapolation technique (BE) was used to estimate V̇O<inf>2</inf> from postexercise measuring, eliminating oronasal mask (OM) during the efforts. Despite its advantage, literature presents discrepancy in applied methods. Thus, the first aim of this study was to compare different mathematical criteria to estimate values of V̇O<inf>2</inf> during a supramaximal effort (V̇O<inf>2PEAK</inf>), while the second aim was to verify the effects of OM on cycling performance.

METHODS

Twenty-four male cyclists (35±6 years, 81.3±8.9 kg, 180±6 cm) performed three days of tests, with at least 24 h of interval between each test. Firstly, a graded exercise test was applied to determine V̇O<inf>2max</inf> and your correspondent intensity (MAP). The second and the third day were destined to supramaximal efforts at 120% of MAP, performed with (Supra<inf>mask</inf>) and without (Supra<inf>be</inf>) oronasal mask (OM) in a randomized order. After Supra<inf>be</inf>, OM was coupled, and BE was applied. Sixty-six values of V̇O<inf>2</inf> were obtained based on a linear regression fitting.

RESULTS

V̇O<inf>2peak</inf> can be estimated using different curve lengths. However, only curves between 20 and 60 s with extrapolation to 3 s or lesser shows at least one consistent criterion. The 60 s curve extrapoled to -3 s was the most accurate criteria (P=0.723; ES=-0.055; r=0.824; Bias=-0.36 and LoA=7.72 mL.kg.min^-1). Performance was not impaired with OM and was similar in both condition (P=0.84, ES=0.04).

CONCLUSIONS

We conclude that it was possible to accurately estimate V̇O<inf>2</inf> values of a supramaximal effort without any respiratory apparatus with a time-efficient analysis. Therefore, we recommended the use of a 60 seconds V̇O<inf>2</inf> curve analysis with a negative extrapolation for 3 seconds.

Dynamics of Recovery of Physiological Parameters After a Small-Sided Game in Women Soccer Players

Purpose: Training methods based on small-sided game (SSG) seem to promote physiological and tactical benefits for soccer players as they present characteristics more specific to the game. Thus, the main objective of the present study was to analyze the hormonal, biochemical, and autonomic parameters in an acute manner and the recovery dynamics (up to 72 h after) in a SSG. Methods: Thirteen professional female soccer players participated in the study (18.8 ± 0.8 years, body mass 59.4 ± 6.2 kg, and height 1.68 ± 0.05 m). During and after the SSG session (4 min × 4 min separated by 3 min of passive interval and 120 m² coverage per player), autonomic modulation was analyzed in the time and frequency domains using heart rate variability, and blood samples (5 ml) were collected before (0 h) and after (10 min and 24, 48, 72 h) the SSG for biochemical and hormonal analysis. Results: The SSG induced an increase effect for LF (low frequency) (92,52%; Very likely increase) and a decrease effect for HF (high frequency) values (-65,72%; Very likely decrease), after 10 min of recovery. The LF/HF increase after 10 min of recovery (386,21%; Very likely increase). The RMSSD (square root of the mean squared differences of the successive N-N intervals) and pNN50 (measure of the number of adjacent NN intervals which differ by more than 50 ms) values presented a decrease effect 10 min after SSG (61,38%; Very likely decrease and-90%; Very likely decrease). The CK (creatine kinase) values presented no changes 10 min after SSG. The LDH (lactate dehydrogenase) values presented an increase effect 10 min after the SSG (19,22%; Likely increase). Both testosterone and cortisol concentrations presented the same behavior after SSG, where no alterations were observed with after 10 min (<0,37%; Most likely trivial). Conclusion: The SSG promoted significant cardiovascular stress that was restored within the first 24 h of recovery. Parasympathetic parameters continued to increase while sympathetic parameters declined significantly during the 72 h of recovery. In addition, the reduced game did not alter biochemical or hormonal responses during the 72 h.

Anaerobic Contribution Determined in Swimming Distances: Relation with Performance

Total anaerobic contribution (TAn) can be assessed by accumulated oxygen deficit, and through sum of glycolytic and phosphagen contribution which enable the evaluation of TAn without influences on mechanical parameters. However, little is known about the difference of TAn within swimming distances. Therefore, the objectives of the present study were to determine and compare the TAn in different performances using the backward extrapolation technique and amount of lactate accumulated during exercise, and relate it with swimming performance. Fourteen competitive swimmers performed five maximal front crawl swims of 50, 100, 200, 400, and 800 m. The total phosphagen (AnAl) and glycolytic (AnLa) contributions were assumed as the fast component of post-exercise oxygen consumption (EPOC_FAST) and amount of blood lactate accumulated during exercise, respectively. TAn was the sum of AnAl and AnLa. Significantly lower values of AnLa were observed in the 800 m (p < 0.01) than other distances. For AnAl, the 50 m performance presented the lowest values, followed by 100 and 800 m (p < 0.01). The highest values of AnAl were observed in the 200 and 400 m (p > 0.13). The TAn was significantly higher in the 200 and 400 m performances than observed at 50 and 800 m (p < 0.01). Anaerobic contributions were correlated with 50, 100, 200, and 400 m performances (p < 0.01). The AnAl contribution was not correlated with 400 m performance. Anaerobic parameters were not correlated with 800 m performance. In conclusion, the highest values of anaerobic contribution were observed in the 200 and 400 m distances. Moreover, TAn is important to performances below 400 m, and may be used in training routines.

Effects of taurine on markers of muscle damage, inflammatory response and physical performance in triathletes

BACKGROUND

The practice of prolonged exercise with high intensity, as seen in triathlon training, can cause physiological imbalances that might result in muscle fatigue, muscle damage and changes in systemic inflammatory response, thus reduce the athletes' physical performance, therefore, both adequate total caloric and macronutrient intake also the use of a specific ergogenic aid, as taurine supplementation would be an alternative to prevent inflammation and muscle damage. In order to verify the effects of 8 weeks of taurine and chocolate milk supplementation, markers of muscle damage, inflammation, and aerobic capacity were quantified in triathletes.

METHODS

A double-blind, crossover, randomized study was conducted with 9 male long-distance triathletes, aged 25-35 years. Supplementation of 3 g of taurine (TAU) or placebo (PLA) associated with 400 mL low fat chocolate milk was performed during an 8-week period. In order to verify the effects of the supplementation protocol markers of muscle damage as lactate dehydrogenase (LDH) and creatine kinase (CK), and inflammatory markers tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were quantified, also triathletes' performance was evaluated by exhaust test on a treadmill.

RESULTS

It was observed a significant increase in taurine and CK plasma levels after TAU supplementation (P=0.02 and P=0.01, respectively). However, LDH concentrations did not differ significantly after the supplementations performed, and there were no changes in physical performance parameters; anaerobic threshold, perceived exertion, heart rate, and the concentrations of IL-6 and TNF-α.

CONCLUSIONS

Taurine supplementation did not provide benefits on performance and muscle damage in triathletes.

Lactacidemic variation and movement patterns during anaerobic power test

BACKGROUND

After the Running Anaerobic Sprint Test (RAST) high blood lactate concentrations ([La-]) are found. However, no study verified the behavior of this metabolite during RAST. For this, the aim of the present study was to verify the implications of increase [La-] on movement patterns' in RAST performance.

METHODS

Six healthy and active individuals (21.8±3.1 years, 70.9±10.8 kg and 179.7±3.3 cm) executed a standardized warm-up. Two minutes later, subjects performed RAST composed of six maximal 35-m bouts separated by 10 s of passive recovery. During RAST, 14 cameras monitored the subjects to determine tridimensional and bi-dimensional mechanics. [La-] were determined before warm-up, between each bout and after RAST.

RESULTS

Significant difference in performance were found after the fifth (5.1±0.1 s) and sixth (5.4±0.3 s; P<0.04) bout in relation to the first up to fourth effort. Fatigue indexes (FI% and FIREAL) were higher from fifth bout (19.2±9.4%; 19.3±10.9%; P<0.05). No significant difference was observed in [La-] on fifth and sixth bout (8.2±2.4 mM and 9.2±2.1 mM) however, both were different from all other bouts. Flight time was different between the fifth bout (0.16±0.03 s) when compared with the first (0.12±0.01 s; P=0.01) and second (0.13±0.02s; P=0.03) bouts.

CONCLUSIONS

RAST performance can be influenced by physiological changes. Biomechanical behavior does not alter performance without a sum of physiological events.

Combined Training (Aerobic Plus Strength) Potentiates a Reduction in Body Fat but Demonstrates No Difference on the Lipid Profile in Postmenopausal Women When Compared With Aerobic Training With a Similar Training Load

The aim of this study was to verify the effects of aerobic and combined training on the body composition and lipid profile of obese postmenopausal women and to analyze which of these models is more effective after equalizing the training load. Sixty-five postmenopausal women (age = 61.0 ± 6.3 years) were divided into 3 groups: aerobic training (AT, n = 15), combined training (CT [strength + aerobic], n = 32), and control group (CG, n = 18). Their body composition upper body fat (TF), fat mass (FM), percentage of FM, and fat-free mass (FFM) were estimated by dual-energy x-ray absorptiometry. The lipid profile, total cholesterol, high-density lipoprotein (HDL) cholesterol, and low-density lipoprotein cholesterol were assessed. There was a statistically significant difference in the TF (AT = -4.4%, CT = -4.4%, and CG = 1.0%, p = 0.001) and FFM (AT = 1.7%, CT = 2.6%, and CG = -1.4%, p = 0.0001) between the experimental and the control groups. Regarding the percentage of body fat, there was a statistically significant difference only between the CT and CG groups (AT = -2.8%, CT = -3.9%, and CG = 0.31%; p = 0.004). When training loads were equalized, the aerobic and combined training decreased core fat and increased FFM, but only the combined training potentiated a reduction in percentage of body fat in obese postmenopausal women after the training program. High-density lipoprotein-c levels increased in the combined group, and the chol/HDL ratio (atherogenic index) decreased in the aerobic group; however, there were no significant differences between the intervention programs. Taken together, both the exercise training programs were effective for improving body composition and inducing an antiatherogenic status.

Tethered 3-min all-out test did not predict the traditional critical force parameters in inexperienced swimmers

BACKGROUND

Critical power model can be performed in tethered swimming (i.e. critical force model). Although critical force can be used to prescribe aerobic training, its determination depends on at least three exhaustive efforts in altered days. In this context, previously studies have demonstrate that critical power model can be estimated by a single 3-min all-out test (3MT), which was not investigated in swimming yet. Thus, the aim of this study was to compare the parameters obtained during the tethered swimming 3MT to those obtained during the traditional critical force model.

METHODS

Seven swimmers (four female and three male) underwent a tethered swimming 3MT and three exhaustive efforts to determine the traditional critical force parameters (i.e. critical force [CF] and anaerobic impulse capacity [AIC]).

RESULTS

The critical force (CF3-MIN) and force-time integral above the CF3-MIN (AIC3-MIN) determined during the tethered 3MT were not different to CF and AIC, respectively (P value >0.55). However, these parameters were not correlated (P value >0.45). In addition, we verified large limits of agreement between CF3MIN and CF (±19.7 N), which was also observed between AIC3MIN and AIC (±0.84 Log[N·min]).

CONCLUSIONS

These findings demonstrated that tethered 3MTs should not be used to predict traditional critical force parameters, at least when the swimmers are inexperienced in long tethered all-out efforts.

Determination of VO2-Intensity Relationship and MAOD in Tethered Swimming

This study aimed to test the reproducibility of the maximal accumulated oxygen deficit (MAOD) values and VO2-intensity relationship parameters as measured during tethered swimming. 9 swimmers performed an incremental test to determine the maximal aerobic force (MAF), 6 submaximal efforts to develop VO2-intensity relationship, and an exhaustive effort to determine MAOD. The tests were performed twice. The reproducibility of the measurements was tested using intraclass correlation (ICC), typical error (TE) and coefficient of variation (CV). High levels of reproducibility were observed for MAF (TE=2.6 N; CV=4.3%; ICC=0.98) and VO2-intensity relationship parameters, as intercept (TE=0.01 L.min(-1); CV=11.4%; ICC=0.97), slope (TE=0.002 L.min(-1).N(-1); CV=3.1%; ICC=0.97) and coefficient of determination (TE=0.02; CV=1.8%; ICC=0.47). The MAOD values measured during the test (2.9±1.1 L and 45.3±14.0 mL.Kg(-1)) and retests (2.9±1.1 L and 45.2±12.6 mL.Kg(-1)) were highly correlated (absolute values: ICC=0.93; relative to body mass values: ICC=0.89) and presented low values of TE (0.3 L and 4.3 mL.Kg(-1)) and CV (9.5% for absolute and 9.6% for relative to body mass values). Thus, we demonstrated the potential use of tethered swimming to assess anaerobic capacity in an aquatic environment.

Relationship of aerobic and anaerobic parameters with 400 m front crawl swimming performance

The aims of the present study were to investigate the relationship of aerobic and anaerobic parameters with 400 m performance, and establish which variable better explains long distance performance in swimming. Twenty-two swimmers (19.1±1.5 years, height 173.9±10.0 cm, body mass 71.2±10.2 kg; 76.6±5.3% of 400 m world record) underwent a lactate minimum test to determine lactate minimum speed (LMS) (i.e., aerobic capacity index). Moreover, the swimmers performed a 400 m maximal effort to determine mean speed (S400m), peak oxygen uptake (V.O2PEAK) and total anaerobic contribution (C_ANA). The C_ANA was assumed as the sum of alactic and lactic contributions. Physiological parameters of 400 m were determined using the backward extrapolation technique (V.O2PEAK and alactic contributions of C_ANA) and blood lactate concentration analysis (lactic anaerobic contributions of C_ANA). The Pearson correlation test and backward multiple regression analysis were used to verify the possible correlations between the physiological indices (predictor factors) and S400m (independent variable) (p < 0.05). Values are presented as mean ± standard deviation. Significant correlations were observed between S400m (1.4±0.1 m·s^-1) and LMS (1.3±0.1 m·s^-1; r = 0.80), V.O2PEAK (4.5±3.9 L·min^-1; r = 0.72) and C_ANA (4.7±1.5 L·O₂; r= 0.44). The best model constructed using multiple regression analysis demonstrated that LMS and V.O2PEAK explained 85% of the 400 m performance variance. When backward multiple regression analysis was performed, C_ANA lost significance. Thus, the results demonstrated that both aerobic parameters (capacity and power) can be used to predict 400 m swimming performance.

Running-based Anaerobic Sprint Test as a Procedure to Evaluate Anaerobic Power

The aim of this study was to evaluate the use of the running anaerobic sprint test (RAST) as a predictor of anaerobic capacity, compare it to the maximal accumulated oxygen deficit (MAOD) and to compare the RAST's parameters with the parameters of 30-s all-out tethered running on a treadmill. 39 (17.0±1.4 years) soccer players participated in this study. The participants underwent an incremental test, 10 submaximal efforts [50-95% of velocity correspondent to VO(2MAX) (vVO(2MAX))] and one supramaximal effort at 110% of vVO(2MAX) for the determination of MAOD. Furthermore, the athletes performed the RAST. In the second stage the 30-s all-out tethered running was performed on a treadmill (30-s all-out), and compared with RAST. No significant correlation was observed between MAOD and RAST parameters. However, significant correlations were found between the power of the fifth effort (P5) of RAST with peak and mean power of 30-s all-out (r=0.73 and 0.50; p<0.05, respectively). In conclusion, the parameters from RAST do not have an association with MAOD, suggesting that this method should not be used to evaluate anaerobic capacity. Although the correlations between RAST parameters with 30-s all-out do reinforce the RAST as an evaluation method of anaerobic metabolism, such as anaerobic power.

Correlation between heart rate variability indexes and aerobic physiological variables in patients with COPD

BACKGROUND AND OBJECTIVE

Previous studies have shown a relationship between the level of physical fitness and autonomic variables. However, these relationships have not been investigated in patients with chronic obstructive pulmonary disease (COPD). The objective of this study was to correlate the resting heart rate variability (HRV) indexes with aerobic physiological variables obtained at a maximal exercise test in patients with COPD.

METHODS

Thirty-seven patients with COPD (63 (59-70) years; 46 (35.4-63.7) forced expiratory volume in 1 s (FEV1)%) underwent assessment of autonomic modulation at rest for 20 min to determine the HRV indexes in time and frequency domains. Soon after that, the patients performed an incremental exercise test to determine the anaerobic threshold (GET), the peak oxygen uptake (VO 2PEAK) and the velocity corresponding to VO 2PEAK (vVO 2PEAK).

RESULTS

The indexes that express parasympathetic component as RMSSD (11.4 [7.5-23.8], HF (ms(2)) (35 [17-195] and SD1 (8.1 [5.3-16.8]), correlated with GET (r = 0.39; r = 0.43; r = 0.39 respectively). The indexes that represent the overall variability, SDNN (19.5 [13.9-28.8]), LF (ms(2)) (111 [38-229]), and SD2 (26.8 [18.6-35.4]) correlated with vVO 2PEAK (r = 0.37; r = 0.38; r = 0.37; r = 0.44; r = 0.43; r = 0.46 respectively). Likewise, the indexes LF (ms(2)), LF (nu) (63.2 [46-77,9]), HF (nu) (36.8 [22.1-54]), and LF/HF (1.7 [0.9-3.5]) correlated with VO 2PEAK (r = 0.35; r = 0.35; r = -0.35; r = 0.40 respectively).

CONCLUSIONS

This study demonstrated that HRV indexes at rest may become a predictive tool for aerobic capacity in COPD patients after the development of more consistent methods.