Net Heart Rate for Estimating Oxygen Consumption in Active Adults.

The aim of this study was to verify the accuracy of predicting oxygen consumption (O2) in predominantly aerobic activities based on net heart rate (netHR), sex, and body mass index (BMI) in active adults. NetHR is the value of the difference between the resting HR (HRrest) and the average HR value obtained during a given session or period of physical activity. These activities must be continuous, submaximal, and of a stabilized intensity. The magnitude of the netHR depends mainly on the intensity of the exercise. The HR is measured in beats per minute (bpm). A total of 156 participants, 52 women and 104 men, between the ages of 18 and 81, had their netHR and net oxygen intake (netVO2) assessed. There were 79 participants in group 1 (prediction sample) (52 males and 27 females). There were 77 people in group 2 (validation sample) (52 males and 25 females). The results of the multiple linear regression showed that netVO2 (R2 = 85.2%, SEE = 3.38) could be significantly predicted by sex (p < 0.001), netHR (p < 0.001), and BMI (p < 0.001). The Bland-Altman plots satisfied the agreement requirements, and the comparison of the measured and estimated netVO2 revealed non-significant differences with a trivial effect size. We calculated the formula NetVO2 (mL/(kg·min)) = 16 + 3.67 (sex) + 0.27 (netHR) - 0.57 (BMI) to predict netVO2, where netVO2 is the amount of oxygen uptake (mL/(kg·min)) above the resting value, netHR is the heart rate (beats per minute) above the resting value measured during exercise, sex is equal to zero for women and one for men, and BMI is the body mass index. In addition, based on the knowledge of VO2, it was possible to estimate the energy expenditure from a particular training session, and to determine or prescribe the exercise intensity in MET (metabolic equivalent of task).

StepTest4all: Improving the Prediction of Cardiovascular Capacity Assessment in Young Adults.

Cardiovascular capacity, expressed as maximal oxygen uptake (VO2max), is a strong predictor of health and fitness and is considered a key measure of physiological function in the healthy adult population. The aim of this study was to investigate the influence of the physical activity levels (PAlevel) of participants in the StepTest4all (validated protocol for the estimation of VO2max in adults). The sample consisted of 69 participants, including 27 women (age 21.7 ± 3.6 years; body mass = 63.5 ± 14.8 kg; height = 1.64 ± 0.06 m; body mass index = 23.7 ± 5.3 kg/m2) and 42 men (aged 21.7 ± 3.4 years; body mass = 72.0 ± 7.3 kg; height = 1.77 ± 0.07 m; body mass index = 23.1 ± 2.1 kg/m2). The participants were assigned to one of the two groups: (i) the VO2max prediction group and (ii) the prediction model validation group. In the multiple linear regression, the following predictors of VO2max remained significant: sex (p < 0.001), physical activity level (p = 0.014), and HRR60 (p = 0.020). The prediction equation (R2 = 74.0%, SEE = 4.78) showed a close and strong relationship between the measurements and can be expressed as follows: VO2max = 17.105 + 0.260·(HRR60) + 8.563·(sex) + 4.097·(PAlevel), in which HRR60 is the magnitude of the HR decrease (bpm) in one minute immediately after stopping the step, and sex: men = 1, women = 0, and PAlevel is level 1 (low), level 2 (moderate), and level 3 (high). The StepTest4all was shown to be a suitable method for estimating cardiovascular capacity, expressed as VO2max, in young adults. Retaining PAlevel as a significant predictor allows us to better individualize the participants' VO2max.

Effects of a 16-Week Training Program with a Pyramidal Intensity Distribution on Recreational Male Cyclists.

Different training intensity distributions (TIDs) have been proposed to improve cycling performance, especially for high-competition athletes. The objectives of this study were to analyze the effect of a 16-week pyramidal training intensity distribution on somatic and power variables in recreational cyclists and to explore the training zone with the greatest impact on performance improvement. The sample consisted of 14 male recreational cyclists aged 41.00 ± 7.29 years of age. A number of somatic variables were measured. During an incremental protocol, power at a 4 mMol·L-1 blood lactate concentration (P4), corresponding power to body mass ratio (P/W P4), and heart rate (HR P4) were also measured. Among the somatic variables, the percentage of fat mass showed the greatest improvement between moments (p < 0.001, d = 0.52). Both P4 (p < 0.001, d = 1.21) and P/W P4 (p < 0.001, d = 1.54) presented a significant increase between moments. The relative improvement in P4 (% P4) showed a significant correlation (Rs = 0.661, p = 0.038) and relationship (R2 = 0.61, p = 0.008) mainly with training zone Z2 (blood lactate levels ≥ 2 and <4 mMol·L-1). It seems that spending more time in Z2 promoted an improvement in both somatic and power variables in recreational cyclists.

Interaction of Kinematic, Kinetic, and Energetic Predictors of Young Swimmers' Speed.

PURPOSE: The aim of this study was to assess the interaction of kinematic, kinetic, and energetic variables as speed predictors in adolescent swimmers in the front-crawl stroke. DESIGN: Ten boys (mean age [SD] = 16.4 [0.7] y) and 13 girls (mean age [SD] = 14.9 [0.9] y) were assessed. METHODS: The swimming performance indicator was a 25-m sprint. A set of kinematic, kinetic (hydrodynamic and propulsion), and energetic variables was established as a key predictor of swimming performance. Multilevel software was used to model the maximum swimming speed. RESULTS: The final model identified time (estimate = -0.008, P = .044), stroke frequency (estimate = 0.718, P < .001), active drag coefficient (estimate = -0.330, P = .004), lactate concentration (estimate = 0.019, P < .001), and critical speed (estimate = -0.150, P = .035) as significant predictors. Therefore, the interaction of kinematic, hydrodynamic, and energetic variables seems to be the main predictor of speed in adolescent swimmers. CONCLUSIONS: Coaches and practitioners should be aware that improvements in isolated variables may not translate into faster swimming speed. A multilevel evaluation may be required for a more effective assessment of the prediction of swimming speed based on several key variables rather than a single analysis.

Prevalence of Type 2 Diabetes, Impaired Fasting Glucose, and Diabetes Risk in an Adult and Older North-Eastern Portuguese Population.

The aims of this study were (1) to evaluate the prevalence of type 2 diabetes (T2D) in a middle-aged north-eastern Portuguese population, (2) to analyze the prevalence of impaired fasting glucose (IFG), and (3) to assess the risk of T2D in this community-based sample. An exploratory, retrospective, and cross-sectional study was conducted from a total of 6570 individuals aged 18-102 years, among which 3865 were women (57.4 ± 18.1 years) and 2705 were men (60.0 ± 16.8 years). T2D diagnosis, IFG, and the diabetes risk score (low to very high risk) were assessed. The prevalence of T2D in this adult and an older north-eastern Portuguese population was 17.4%. A higher prevalence of T2D was reported in men (22.2%) than in women (14.0%); however, this was without significant differences (p = 0.086). Otherwise, the prevalence of T2D was significantly different among the age groups and increased with age (p < 0.001). Regarding IFG, a higher percentage of cases was observed in men (14.1%) than in women (8.4%) (p < 0.001). The risk of developing T2D in the next 10 years showed an association with sex and age group (p < 0.001) with a small-to-moderate effect (V = 0.1-0.3). Men and the elderly had the highest percentage of cases in the moderate-to-very high-risk bands. The current research confirmed a higher prevalence of T2D, IFG, and diabetes risk than previous Portuguese epidemiological reports. The results also suggest potential prediabetes cases, which should be carefully monitored. The current research adds evidence to the worldwide trend of the increasing prevalence of T2D and intermediate hyperglycemia (i.e., prediabetes).

Race Analysis and Determination of Stroke Frequency - Stroke Length Combinations during the 50-M Freestyle Event.

The aims of this study were to: (1) analyze and compare the stroke kinematics between junior and senior elite male swimmers in every section of the race during the 50-m freestyle event, and; (2) identify stroke frequency (SF)-stroke length (SL) combinations on swim speed independently for junior and senior swimmers in each section of the 50-m freestyle event. Eighty-six junior swimmers (2019) and 95 seniors (2021) competing in the 50-m long course meter LEN Championships were analyzed. The t-test independent samples (p ≤ 0.05) were used to compare juniors and seniors. The SF and SL combinations on swim speed were explored using three-way ANOVAs. Senior swimmers were significantly faster in the 50-m race than juniors (p < 0.001). Speed presented the largest significant difference (p < 0.001) in section S0-15 m (start until the 15th meter mark) being seniors fastest. Both junior and senior swimmers revealed a significant categorization (p < 0.001) by stroke length and stroke frequency in each race section. It was possible to model several SF-SL combinations for seniors and juniors in each section. The fastest swim speed in each section, for seniors and juniors independently, was achieved by a SF-SL combination that may not be the fastest SF or the longest SL. Coaches and swimmers must be aware that despite the 50-m event being an all-out bout, several SF-SL combinations were observed (independently for juniors and seniors), and they differ between race sections.

Stability analysis and prediction of pacing in elite 1500 m freestyle male swimmers.

This study aimed to analyse the stability of elite male long-distance swimmers (1500 m), and to identify the main predictors related to the pace. The performance of 16 elite male swimmers (22.59 ± 2.10 years-old) participating in the 1500 m event at the 2016 (London) and 2018 (Glasgow) LEN European Aquatic Championships were analysed. The lap performance, clean swim performance, turn performance, and a set of stroke mechanics variables were assessed. The lap performance presented a significant and moderate variation with all laps included (p < 0.001) and deleting the first and last lap (p = 0.002). Swimmers were significantly faster in the first half in comparison of the second. The total turn also presented a significant and moderate variation. The hierarchical linear modelling retained the time (estimate = 0.0019, p = 0.007), stroke frequency (estimate = -27.49, p < 0.001) and stroke length (estimate = -6.55, p < 0.001) as the main predictors of the clean swim performance. By contrast to the analysis based on the lap performance, clean swim performance presented a non-significant variation. Coaches should be aware that stroke length maintenance could negatively affect the clean swim performance, whereas a small increase of stroke frequency may present a meaningful enhancement of the total race time.

Relationship between Oxygen Uptake Reserve and Heart Rate Reserve in Young Male Tennis Players: Implications for Physical Fitness Monitoring.

The aims of this study were to (i) verify the relationship between reserve oxygen uptake (VOreserve) and reserve heart rate (HRreserve) in young male tennis players, and (ii) understand the relationship between oxygen uptake (VO2) measured at the end of a tennis drill and recovery heart rate (HRrecovery) after the tennis drill. Ten young male tennis players (16.64 ± 1.69 years; 62.36 ± 6.53 kg of body mass; 175.91 ± 5.26 cm of height) were recruited from the National Tennis Association. Players were instructed to perform a tennis drill based on an incremental intensity protocol. Afterward, three levels of intensity were used based on VO2reserve and HRreserve. A significant variance was observed between levels (VO2reserve and HRreserve = p < 0.001). VO2reserve presented a significant and high agreement with HRreserve. The mean data revealed non-significant differences (p > 0.05), a very high relationship of linear regression (R2 = 82.4%, p < 0.001), and high agreement in Bland Altman plots. VO2, at the highest level of intensity (>93%), presented a significant correlation with HRrecovery during the immediate 30 s after the drill (rs = 0.468, p = 0.028). Tennis coaches or instructors must be aware of the differences between monitoring or prescribing training intensities based on HRreserve or HRmax. They can also use HRrecovery for 30 s immediately after exercise to verify and understand the variation in their players' cardiorespiratory capacities.

Validation of StepTest4all for Assessing Cardiovascular Capacity in Young Adults.

BACKGROUND: Cardiovascular capacity, expressed as maximal oxygen uptake (VO2max), is a strong predictor of health and fitness and is considered a key measure of physiological function in the healthy adult population. The purpose of this study was to validate a specific step test (StepTest4all) as an adequate procedure to estimate cardiovascular capacity in young adults. METHODS: The sample was composed of 56 participants, including 19 women (aged 21.05 ± 2.39 years, body mass = 57.50 ± 6.64 kg, height = 1.62 ± 0.05 m, body mass index = 22.00 ± 2.92 kg/m2) and 37 men (aged 22.05 ± 3.14 years, body mass = 72.50 ± 7.73 kg, height = 1.76 ± 0.07 m, body mass index = 23.34 ± 2.17 kg/m2). Participants were included in one of the following groups: (i) the group used to predict the VO2max, and (ii) the group used to validate the prediction model. All participants performed the StepTest4all protocol. The step height and the intensity of the effort was determined individually. Heart rate and oxygen uptake were measured continuously during rest, effort, and recovery phases. The validation process included the following three stages: (i) mean data comparison, (ii) simple linear regression, and (iii) Bland-Altman analysis. RESULTS: The linear regression retained, as significant predictors of the VO2max, sex (p < 0.001) and heart rate recovery for one minute (p = 0.003). The prediction equation revealed a high relationship between measurements (R2 = 63.0%, SEE = 5.58). The validation procedure revealed non-significant differences (p > 0.05) between the measured and estimated maximal oxygen uptake, high relationship (R2 = 63.3%), and high agreement with Bland-Altman plots. Thus, VO2max can be estimated with the formula: VO2max = 22 + 0.3 · (HRR1min) + 12 · (sex), where HRR1min is the magnitude of the HR decrease (bpm) in one minute immediately after the step was stopped, and sex: men = 1, women = 0. CONCLUSIONS: The StepTest4all is an adequate procedure to estimate cardiovascular capacity, expressed as VO2max, in young adults. In addition, it is possible to determine the qualitative level of cardiovascular capacity from the heart rate recovery for one minute, more specifically, poor: <20, moderate: 20 to 34, good: 35 to 49, and excellent: ≥50. This procedure has the benefit of being simple to apply and can be used by everyone, even at home, without specialist supervision.

Structural Equation Modelling for Predicting the Relative Contribution of Each Component in the Metabolic Syndrome Status Change.

Understanding the factor weighting in the development of metabolic syndrome (MetS) may help to predict the progression for cardiovascular and metabolic diseases. Thus, the aim of this study was to develop a confirmatory model to describe and explain the direct and indirect effect of each component in MetS status change. A total of 3581 individuals diagnosed with MetS, aged 18−102 years, were selected between January 2019 and December 2020 from a community-representative sample of Portuguese adults in a north-eastern Portuguese region to test the model's goodness of fit. A structural equation modelling (SEM) approach and a two-way ANOVA (age × body composition) were performed to compare the relative contribution of each MetS component using joint interim statement (JIS). Waist circumference (ß = 0.189−0.373, p < 0.001), fasting glucose (ß = 0.168−0.199, p < 0.001) and systolic blood pressure (ß = 0.140−0.162, p < 0.001) had the highest direct effect on the change in MetS status in the overall population and concerning both sexes. Moreover, diastolic blood pressure (DBP), triglycerides (TG) and high-density lipoprotein cholesterol (HDL-c) had a low or non-significant effect. Additionally, an indirect effect was reported for age and body composition involving the change in MetS status. The findings may suggest that other components with higher specificity and sensitivity should be considered to empirically validate the harmonised definition of MetS. Current research provides the first multivariate model for predicting the relative contribution of each component in the MetS status change, specifically in Portuguese adults.

The aging influence on cardiorespiratory, metabolic, and energy expenditure adaptations in head-out aquatic exercises: Differences between young and elderly women.

The purpose of this study was to: (1) establish the relationship between acute physiological responses and musical cadence; and (2) compare physiologic responses between young and older women. Eighteen older (mean = 65.06 ± 5.77 years) and 19 young (mean = 22.16 ± 2.63 years) women underwent an intermittent and progressive protocol performing the head-out aquatic exercise the "rocking horse." Results showed that older women demonstrated lower mean heart rate, blood lactate concentration (bLa), and oxygen uptake (VO2) at rest. Hierarchical linear modeling showed that variations in the rating of perceived effort and individual metabolic equivalent of task did not differ significantly by age group. However, during exercise, physiological responses of younger women were significantly different than for older women: in mean values, for each increased musical beat per minute, mean bLa was 0.003 mmol/l, VO2 was 0.024 ml/kg/min, and energy expenditure was 0.0001 kcal/kg/min higher for younger women. This study shows that increases in musical cadence increased the cardiorespiratory, metabolic, and energy expenditure responses. However, these responses during increasing intensity seemed to differ between young and older women, with lower values for the elderly group, when performing head-out aquatic exercises.

Longitudinal study in male swimmers: a hierachical modeling of energetics and biomechanical contributions for performance.

The aim of this study was to assess the pooled and individual response of male swimmers over two consecutive years of training and identify the energetic and biomechanical factors that most contributed for the final performance. Nine competitive swimmers (20.0 ± 3.54 years old; 10.1 ± 3.41 years of training experience; 1.79 ± 0.07 m of height; 71.34 ± 8.78 kg of body mass; 22.35 ± 2.02 kg·m(-2) of body mass index; 1.86 ± 0.07 m of arm span; 116.22 ± 4.99 s of personal record in the 200 m long course freestyle event) performed an incremental test in six occasions to obtain the velocity at 4 mmol of blood lactate (V4) and the peak blood lactate concentrations (Lapeak) as energetics, and the stroke frequency (SF), stroke length (SL), stroke index and swim efficiency as biomechanical variables. Performance was determined based on official time's lists of 200 m freestyle event. Slight non-significant improvements in performance were determined throughout the two season period. All energetic and biomechanical factors also presented slight non-significant variations with training. Swimmers demonstrat-ed high inter-individual differences in the annual adaptations. The best performance predictors were the V4, SF and SL. Each unit of change V4, SF and SL represented an enhancement of 0.11 s, 1.21 s and 0.36 s in performance, respectively. The results show that: (i) competitive male swimmers need at least two consecutive seasons to have slight improvements in performance, energetics and biomechanical profiles; (ii) major improvements in competition performance can be accomplished by improving the V4, SF and SL based on the individual background. Key PointsElite swimmers are able to demonstrate slight changes in performance, energetic and biomechanical characteristics at least during two seasons of training;Additional improvements in competition performance can be accomplished by manipulating the V4, SF and SL based on the individual background.Each unit of change V4, SF and SL represent an enhancement of 0.11 s, 1.21 s and 0.36 s in performance, respectively.

Longitudinal interventions in elite swimming: a systematic review based on energetics, biomechanics, and performance.

Longitudinal information requires the notion of repeated measurements throughout time. Such data is important because it allows the determination of the effectiveness of an intervention program. Research in competitive swimming has given special emphasis to energetics and biomechanics as determinant domains to improve performance. The purpose of this systematic review was to summarize longitudinal evidences on the energetic, biomechanical, and performance status of elite swimmers. A computerized search was made in 6 databases, conference proceedings, and department files. The 28 studies that satisfied the inclusion criteria were selected for analysis. Studies' qualitative evaluation was made by 2 independent reviewers using the Quality Index. These studies were then gathered into 3 main categories according to their reported data: energetics (n = 18), biomechanics (n = 9), and performance (n = 8). The conclusions were as follows: (a) elite swimmers are able to demonstrate from slight to substantial changes in their performance and energetic and biomechanical profiles within and between seasons; (b) the magnitude of change is dependent on the characteristics of the training programs, the duration of the intervention, and subject's gender; and (c) future research should emphasize the use of more complex procedures to improve the quality of the interventions.

Tracking the performance, energetics and biomechanics of international versus national level swimmers during a competitive season.

The purpose of this study was to track and compare the changes of performance, energetic and biomechanical profiles of international (Int) and national (Nat) level swimmers during a season. Ten Portuguese male swimmers (four Int and six Nat level subjects) were evaluated on three different time periods (TP(1), TP(2), TP(3)) of the 2009-2010 season. Swimming performance was assessed based on official time's lists of the 200-m freestyle event. An incremental set of 7 × 200 m swims was applied to assess the energetic and biomechanical data. Measurements were made of: (1) velocity at the 4 mmol of lactate levels (V4), stroke index at V4 (SI@V4) and propelling efficiency at V4 (η (p)@V4), as energetic estimators; (2) stroke length at V4 (SL@V4) and stroke frequency at V4 (SF@V4), as biomechanical variables. The results demonstrated no significant variations in all variables throughout the season. The inter-group comparison pointed out higher values for Int swimmers, with statistical differences for the 200 m performance in all time periods. Near values of the statistical significance were demonstrated for the SI@V4 in TP(1) and TP(3). The tracking based on K values was high only for the SI@V4. It is concluded that a high stability can be observed for elite swimmers performance, energetic and biomechanical profiles throughout a single season. Int swimmers are able to maintain a higher energetic and biomechanical capacity than Nat ones at all times. The SI@V4 may be used as an indicator of performance variation.

Stability of elite freestyle performance from childhood to adulthood.

Stability of athletic performance is important for practitioners and coaches, since it allows the selection of appropriate training methods and prediction of ages for best results. We performed a longitudinal study of 1694 season-best performances of 242 elite-standard swimmers throughout their careers, from 12 to 18 years of age. Mean stability (descriptive statistics and one-way repeated-measures ANOVA, followed by a Bonferroni post-hoc test) and normative stability (Cohen's kappa tracking index and the Pearson correlation coefficient) were determined for seven consecutive seasons. Performance improvements in all events were observed (14.36-18.97%). Bonferroni post-hoc tests verified changes in almost all events assessed. Cohen's kappa demonstrated low stability (0.17-0.27) in relative performance. Pearson correlations only became high from 15 to 16 years in the 50-m and 100-m events, and from 16 to 17 years in the 200-m, 400-m, and 1500-m events. Our results show that: (a) swimmers should display a substantial improvement (14-19%) to become elite standard as adults, such as at 18 years; (b) 16 is the age at which the ability to predict adult performance increases markedly.

Tracking the performance of world-ranked swimmers.

Tracking the swimming performance is important to analyze its progression and stability between competitions and help coaches to define realistic goals and to select appropriate training methods. The aim of this study was to track world-ranked male swimmer's performance during five consecutive seasons (from 2003/2004 to 2007/2008) in Olympic freestyle events. An overall of 477 swimmers and 2385 season best performances were analyzed. FINA's male top-150 rankings for long course in the 2007-2008 season were consulted in each event to identify the swimmers included. Best performances were collected from ranking tables provided by the National Swimming Federations or, when appropriate, through an internet database (www. swimranking.net). Longitudinal assessment was performed based on two approaches: (i) mean stability (descriptive statistics and ANOVA repeated measures, followed by a Bonferroni post-hoc test) and; (ii) normative stability (Pearson Correlation Coefficient and the Cohen's Kappa tracking index). Significant variations in the mean swimming performance were observed in all events between all seasons. Performance enhancement was approximately 0.6 to 1 % between seasons leading up to the Olympics and approximately 3 to 4 % for the overall time-frame analyzed. The performance stability based on overall time-frame was moderate for all freestyle events, except in the 50-m (K = 0.39 ± 0.05) where it was low. Self-correlations ranged between a moderate (0.30 ≤ r < 0.60) and a high (r ≥ 0.60) stability. There was also a performance enhancement during all five seasons analyzed. When more strict time frames were used, the analysis of swimming performance stability revealed an increase in the third season. So, coaches should have a long term view in what concerns training design and periodization of world-ranked swimmers, setting the third season of the Olympic Cycle as a determinant time frame, due to performance stability until Olympic Games season. Key pointsWorld-ranked swimmers' performance increased each season by approximately 0.6 to 1% during the five consecutive seasons analyzed.The stability of swimmers' performance based on the overall Olympic cycle period was moderate.Coaches should set the third season of the Olympic Cycle as a determinant milestone. In that specific season, performance turns out to be high when having the Olympic Games season as a main goal.

Longitudinal Study in 3,000 m Male Runners: Relationship between Performance and Selected Physiological Parameters.

The purpose of the present study was to analyze longitudinal changes in 3,000 m running performance and the relationship with selected physiological parameters. Eighteen well-trained male middle-distance runners were measured six times (x3 per year) throughout two consecutive competitive seasons. The following parameters were measured on each occasion: maximal oxygen uptake (VO2max), running economy (RE), velocity at maximal oxygen uptake (vVO2max), velocity at 4mmol L(-1) blood lactate concentration (V4), and performance velocity (km·h(-1)) in 3,000 m time trials. Values ranged from 19.59 to 20.16 km·h(-1), running performance; 197 to 207 mL·kg(-1)·km(-1). RE; 17.2 to 17.7 km·h(-1), V4; 67.1 to 72.5 mL·kg(-1)·min(-1), VO2max; and 19.8 to 20.2 km·h(-1), vVO2max. A hierarchical linear model was used to quantify longitudinal relationships between running performance and selected physiological variables. Running performance decreased significantly over time, between each time point the decrease in running velocity was 0.06 km·h(-1). The variables that significantly explained performance changes were V4 and vVO2max. Also, vVO2max and V4 were the measures most strongly correlated with performance and can be used to predict 3,000 m race velocity. The best prediction formula for 3,000 m running performance was: y = 0.646 + 0.626x + 0.416z (R(2)=0.85); where y = V3,000 m velocity (km·h(-1)), x = V4 (km·h(-1)) and z = vVO2max (km·h(-1)). The high predictive power of vVO2max and V4 suggest that both coaches and athletes should give attention to improving these two physiological variables, in order to improve running performance. Key pointsV4 and vVO2max are the most important physiological variables to explain longitudinal changes in 3000 m running performance;3000 m running performance prediction is better if one uses both V4 and vVO2max in the same formula: y = 0.646 + 0.626x + 0.416z; R(2)=0.85, where y is the Vrace (km/h), x is V4 (km/h) and z is vVO2max (km/h).The V4 and vVO2max can be used for training control purposes.

Effects of musical cadence in the acute physiologic adaptations to head-out aquatic exercises.

The purpose of this study was to analyze the relationships between musical cadence and the physiologic adaptations to basic head-out aquatic exercises. Fifteen young and clinically healthy women performed, immersed to the breast, a cardiovascular aquatic exercise called the "rocking horse." The study design included an intermittent and progressive protocol starting at a 90 b.min(-1) rhythm and increasing every 6 minutes, by 15 b.min(-1), up to 195 b.min(-1) or exhaustion. The rating of perceived effort (RPE) at the maximal heart rate achieved during each bout (HRmax), the percentage of the maximal theoretical heart rate estimated (%HRmax), and the blood lactate concentration ([La-]) were evaluated. The musical cadence was also calculated at 4 mmol.L(-1) of blood lactate (R4), the RPE at R4 (RPE@R4), the HR at R4 (HR@R4), and the %HRmax at R4 (%HRmax@R4). Strong relationships were verified between the musical cadence and the RPE (R2 = 0.85; p < 0.01), the HRmax (R2 = 0.66; p < 0.01), the %HRmax (R = 0.61; p < 0.01), and the [La-] (R2 = 0.54; p < 0.01). The R4 was 148.13 +/- 17.53 b.min, the RPE@R4 was 14.53 +/- 2.53, the HR@R4 was 169.33 +/- 12.06 b.min, and the %HRmax@R4 was 85.53 +/- 5.72%. The main conclusion is that increasing musical cadence created an increase in the physiologic response. Therefore, instructors must choose musical cadences according to the goals of the session they are conducting to achieve the desired intensity.

Energetics and biomechanics as determining factors of swimming performance: updating the state of the art.

The biophysical determinants related to swimming performance are one of the most attractive topics within swimming science. The aim of this paper was to do an update of the "state of art" about the interplay between performance, energetic and biomechanics in competitive swimming. Throughout the manuscript some recent highlights are described: (i) the relationship between swimmer's segmental kinematics (segmental velocities, stroke length, stroke frequency, stroke index and coordination index) and his center of mass kinematics (swimming velocity and speed fluctuation); (ii) the relationships between energetic (energy expenditure and energy cost) and swimmer's kinematics; and (iii) the prediction of swimming performance derived from above mentioned parameters.

Physiological assessment of head-out aquatic exercises in healthy subjects: a qualitative review.

In the last decades head-out aquatic exercises became one of the most important physical activities within the health system. Massive research has been produced throughout these decades in order to better understand the role of head-out aquatic exercises in populations' health. Such studies aimed to obtain comprehensive knowledge about the acute and chronic response of subjects performing head-out aquatic exercises. For that, it is assumed that chronic adaptations represent the accumulation of acute responses during each aquatic session. The purpose of this study was to describe the "state of the art "about physiological assessment of head-out aquatic exercises based on acute and chronic adaptations in healthy subjects based on a qualitative review. The main findings about acute response of head-out aquatic exercise according to water temperature, water depth, type of exercise, additional equipment used, body segments exercising and music cadence will be described. In what concerns chronic adaptations, the main results related to cardiovascular and metabolic adaptations, muscular strength, flexibility and body composition improvements will be reported. Key pointsSeveral papers reported consistent and significant improvement in physical fitness (e.g., aerobic capacity, muscular strength, flexibility and body composition) after a program of head-out aquatic exercise with at least eight weeks.Chronic adaptations to head-out aquatic exercise programs are the cumulative result of appropriate acute responses during the exercise session.Appropriate acute adaptations can be obtained taking into account the water temperature, water depth, type of exercise and its variants, the equipment used and the segmental cadence according to the subjects' profile.