Effects of aerobic fitness on oxygen uptake kinetics in heavy intensity swimming

Training zones in competitive swimming: a biophysical approach

Since swimming performance depends on both physical conditioning and technical proficiency, training zones should be built based on physiology and biomechanics inputs to dispose of structured and effective training programs. This paper presents a zone-based swimming training, supported by the oxygen uptake (V ˙ O2) kinetics at low, moderate, heavy, severe and extreme intensities concurrently with lactate and heart rate values. Since technique is vital for efficiently moving through the water, upper limbs frequency and length should also be targeted during the workouts. The index of coordination was also added to our proposal since upper limbs synchronization is a key technical factor. To better establish and characterize a wide range of swimming intensities, the training methods and corresponding contents that better fit each training zone will be suggested. It will be shown that when under/at the anaerobic threshold (at low-to-moderate intensities), swimmers are at homeostasis and can maintain stable internal and external load indicators. However, above that boundary (at heavy and severe intensities), the physiological stable state is no longer observed and the anaerobic metabolism starts contributing significantly, with a technical degradation being more evident when performing near/at the V ˙ O2max intensity. Then, when performing above aerobic power, on typical anaerobic intensities, V ˙ O2 kinetics presents a very evident fast rise, ending abruptly due to exhaustion caused by muscle acidosis. This overall knowledge allows advancing toward more objective training programs and highlights the importance of systematic training control and swimmers' evaluation and advice.

Sex-Specific Accumulated Oxygen Deficit During Short- and Middle-Distance Swimming Performance in Competitive Youth Athletes

INTRODUCTION

Since sex-specific accumulated oxygen deficit (AOD) during high-intensity swimming remains unstudied, this study aimed to assess AOD during 50, 100, and 200 m front-crawl performances to compare the responses between sexes and analyse the effect of lean body mass (LBM).

METHODS

Twenty swimmers (16.2 ± 2.8 years, 61.6 ± 7.8 kg, and 48.8 ± 11.2 kg LBM-50% males) performed 50, 100, and 200 m to determine accumulated oxygen uptake (V̇O_2Ac). The swimmers also performed an incremental test from which five submaximal steps were selected to estimate the oxygen demand (V̇O_2demand) from the V̇O₂ versus velocity adjustment. V̇O₂ was sampled using a gas analyser coupled with a respiratory snorkel. AOD was the difference between V̇O_2demand and V̇O_2Ac, and LBM (i.e. lean mass not including bone mineral content) was assessed by dual-energy X-ray absorptiometry (DXA).

RESULTS

A two-way ANOVA evidenced an AOD increase with distance for both sexes: 19.7 ± 2.5 versus 24.9 ± 5.5, 29.8 ± 8.0 versus 36.5 ± 5.8, and 41.5 ± 9.4 versus 5.2 ± 11.9 ml × kg^-1, respectively, for 50, 100, and 200 m (with highest values for females, P < 0.01). Inverse correlations were observed between LBM and AOD for 50, 100, and 200 m (r = - 0.60, - 0.38 and - 0.49, P < 0.05). AOD values at 10 and 30 s elapsed times in each trial decreased with distance for both sexes, with values differing when female swimmers were compared to males in the 200 m trial (at 10 s: 2.6 ± 0.6 vs. 3.4 ± 0.6; and at 30 s: 7.9 ± 1.7 vs. 10.0 ± 1.8 ml × kg^-1, P < 0.05).

CONCLUSION

LBM differences between sexes influenced AOD values during each trial, suggesting that reduced muscle mass in female swimmers plays a role on the higher AOD (i.e. anaerobic energy) demand than males while performing supramaximal trials.

Repeatability of ventilatory, metabolic and biomechanical responses to an intermittent incremental swimming protocol

OBJECTIVE

This study aimed to determine the repeatability of ventilatory, metabolic and biomechanical variables assessed at a large spectrum of front crawl swimming intensities. We hypothesized a strong agreement (combined with a small range of variation) between a typical step protocol performed in two experimental moments.

APPROACH

Forty competitive swimmers performed a 7 x 200 m front crawl intermittent incremental protocol (0.05 m∙s-1 velocity rises and 30 s intervals) on two different occasions (48-72 h apart). Pulmonary gas exchange and ventilation were continuously measured breath-by-breath, metabolic variables were assessed during the intervals and biomechanical analysis was done at every protocol step.

MAIN RESULTS

Concomitantly with the velocity increment, oxygen uptake, carbon dioxide production, ventilation, respiratory frequency, respiratory exchange ratio, averaged expiratory concentrations, end tidal oxygen and ventilatory equivalents for oxygen and carbon dioxide and blood lactate concentrations rose (p < 0.001), averaged expiratory concentrations and end tidal carbon dioxide and duration of inspiration, expiration and total breathing cycle decreased (p < 0.001), while tidal volume and volumes of oxygen and carbon dioxide expired maintained constant. Stroke frequency and stroke length increased and decreased (respectively) with the swimming velocity raise. No differences between experimental moments were observed in most of the assessed variables (p > 0.05), with a low dispersion (0.49-9.94%) except for lactate concentrations and inspiration and expiration durations (11.00-17.16%). Moderate-nearly perfect direct relationships and a good-excellent degree of reliability between moments were verified for all the assessed variables (r = 0.50-1.00, ICC = 0.76-1.00, p < 0.001), except for respiratory exchange ratio.

SIGNIFICANCE

The reliability analysis confirmed the repeatability of the assessed ventilatory, metabolic and biomechanical variables, with the obtained data well representing swimmers physiological condition when monitoring performance through a commonly used step protocol.

Oxygen uptake kinetics and ventilatory and metabolic parameters do not differ between moderate-intensity front crawl and breaststroke swimming

Pulmonary oxygen uptake ( V ̇ O 2 ) kinetics have been well studied during land-based exercise. However, less is known about V ̇ O 2 kinetics during swimming exercise and comparisons between strokes is non-existent. We aimed to characterize and compare the V ̇ O 2 kinetics, ventilatory,e and metabolic response to constant velocity moderate-intensity freely breathing front crawl (FC) and breaststroke (BR) swimming in a swimming flume. These two strokes reflect predominantly upper body versus lower body modes of swimming locomotion, respectively. Eight trained swimmers (4 females, 20 ± 1 years, 1.74 ± 0.06 m; 66.8 ± 6.3 kg) attended 5-6 laboratory-based swimming sessions. The first two trials determined FC and BR V ̇ O 2 max and the ventilatory threshold (VT), respectively, during progressive intensity swimming to the limit of tolerance. Subsequent trials involved counterbalanced FC and BR transitions from prone floating to constant velocity moderate-intensity swimming at 80% of the velocity at VT (vVT), separated by 30-min recovery. Breath-by-breath changes in pulmonary gas exchange and ventilation were measured continuously using a snorkel and aquatic metabolic cart system. The ventilatory and metabolic responses were similar (p > 0.05) between strokes during maximal velocity swimming, however, vVT and maximal velocity were slower (p < 0.05) during BR . During moderate-intensity swimming, V ̇ O 2 kinetics, ventilatory and metabolic parameters were similar (p > 0.05) between strokes. In conclusion, when breathing ad libitum, V ̇ O 2 kinetics during moderate-intensity constant velocity swimming, and ventilatory and metabolic responses during moderate-intensity and maximal velocity swimming, are similar between FC and BR strokes.

Physiological Responses During High-Intensity Interval Training in Young Swimmers

This study analyzed whether 100- and 200-m interval training (IT) in swimming differed regarding temporal, perceptual, and physiological responses. The IT was performed at maximal aerobic velocity (MAV) until exhaustion and time spent near to maximalVO₂ peak oxygen uptake (⩒O₂peak), total time limit (t_Lim), peak blood lactate [La^-] peak, ⩒O₂ kinetics (⩒O₂K), and rate of perceived exertion (RPE) were compared between protocols. Twelve swimmers (seven males 16.1 ± 1.1 and five females 14.2 ± 1 years) completed a discontinuous incremental step test for the second ventilatory threshold (VT₂), ⩒O₂peak, and MAV assessment. The swimmers subsequently completed two IT protocols at MAV with 100- and 200-m bouts to determine the maximal ⩒O₂ (peak-⩒O₂) and time spent ≥VT₂, 90, and 95% of ⩒O₂peak for the entire protocols (IT₁₀₀ and IT₂₀₀) and during the first 800-m of each protocol (IT_8x100 and IT_4x200). A portable apparatus (K4b²) sampled gas exchange through a snorkel and an underwater led signal controlled the velocity. RPE was also recorded. The Peak-⩒O₂ attained during IT_8x100 and IT_4x200 (57.3 ± 4.9 vs. 57.2 ± 4.6 ml·kg^-1·min^-1) were not different between protocols (p = 0.98) nor to ⩒O₂peak (59.2 ± 4.2 ml·kg^-1·min^-1, p = 0.37). The time constant of ⩒O₂K (24.9 ± 8.4 vs. 25.1 ± 6.3-s, p = 0.67) and [La^-] peak (7.9 ± 3.4 and 8.7 ± 1.5 mmol·L^-1, p = 0.15) also did not differ between IT₁₀₀ and IT₂₀₀. The time spent ≥VT₂, 90, and 95%⩒O₂peak were also not different between IT_8x100 and IT_4x200 (p = 0.93, 0.63, and 1.00, respectively). The RPE for IT_8x100 was lower than that for IT_4x200 (7.62 ± 2 vs. 9.5 ± 0.7, p = 0.01). Both protocols are considered suitable for aerobic power enhancement, since ⩒O₂peak was attained with similar ⩒O₂K and sustained with no differences in t_Lim. However, the fact that only the RPE differed between the IT protocols suggested that coaches should consider that nx100-m/15-s is perceived as less difficult to perform compared with nx200-m/30-s for the first 800-m when managing the best strategy to be implemented for aerobic power training.

[Formula: see text] kinetics and energy contribution in simulated maximal performance during short and middle distance-trials in swimming

PURPOSE

This study aims to analyze swimmers' oxygen uptake kinetics ([Formula: see text]K) and bioenergetic profiles in 50, 100, and 200 m simulated swimming events and determine which physiological variables relate with performance.

METHODS

Twenty-eight well-trained swimmers completed an incremental test for maximal oxygen uptake (Peak-[Formula: see text]) and maximal aerobic velocity (MAV) assessment. Maximal trials (MT) of 50, 100, and 200-m in front crawl swimming were performed for [Formula: see text]K and bioenergetic profile. [Formula: see text]K parameters were calculated through monoexponential modeling and by a new growth rate method. The recovery phase was used along with the blood lactate concentration for bioenergetics profiling.

RESULTS

Peak-[Formula: see text] (57.47 ± 5.7 ml kg^-1 min^-1 for male and 53.53 ± 4.21 ml kg^-1 min^-1 for female) did not differ from [Formula: see text]_peak attained at the 200-MT for female and at the 100 and 200-MT for male. From the 50-MT to 100-MT and to the 200-MT the [Formula: see text]K presented slower time constants (8.6 ± 2.3 s, 11.5 ± 2.4 s and 16.7 ± 5.5 s, respectively), the aerobic contribution increased (~ 34%, 54% and 71%, respectively) and the anaerobic decreased (~ 66%, 46% and 29%, respectively), presenting a cross-over in the 100-MT. Both energy systems, MAV, Peak-[Formula: see text], and [Formula: see text] peak of the MT's were correlated with swimming performance.

DISCUSSION

The aerobic energy contribution is an important factor for performance in 50, 100, and 200-m, regardless of the time taken to adjust the absolute oxidative response, when considering the effect on a mixed-group regarding sex. [Formula: see text]K speeding could be explained by a faster initial pacing strategy used in the shorter distances, that contributed for a more rapid increase of the oxidative contribution to the energy turnover.

Practical Considerations for Assessing Pulmonary Gas Exchange and Ventilation During Flume Swimming Using the MetaSwim Metabolic Cart

Lomax, M, Mayger, B, Saynor, ZL, Vine, C, and Massey, HC. Practical considerations for assessing pulmonary gas exchange and ventilation during flume swimming using the MetaSwim metabolic cart. J Strength Cond Res 33(7): 1941-1953, 2019-The MetaSwim (MS) metabolic cart can assess pulmonary gas exchange and ventilation in aquatic environments. The aims of this study were: (a) to determine the agreement between minute ventilation (VE), pulmonary oxygen uptake (VO2), and carbon dioxide output (VCO2) using the MS and Douglas bag (DB) methods during flume swimming; and (b) to assess the repeatability of these and other MS-derived parameters. Sixteen trained swimmers completed a combined incremental and supramaximal verification cardiopulmonary swimming test to determine maximal VO2, 2 progressive intensity swimming tests during which MS and DB measurements were made (agreement protocol), and 3-4 constant-velocity submaximal swimming tests during which only the MS was used (repeatability protocol). Agreement was determined using limits of agreement (LoA), bias, random error, and 95% confidence intervals with systematic bias assessed using paired samples t-tests. Within-trial and between-trial repeatability were determined using the coefficient of variation (CV) and the repeatability coefficient (CR). Where data were heteroscedastic, LoA and CR were log-transformed, antilogged, and displayed as ratios. MetaSwim underestimated peak VO2 and VCO2 (≤0.39 L·min) and VE (9.08 L·min), whereas submaximal values varied between 2 and 5% for CV and ±1.09-1.22 for ratio CR. The test-retest CV during constant-velocity swimming for VE, tidal volume, breathing frequency, VO2, VCO2, and end-tidal pressures of O2 and CO2 was <9% (ratio CR of ±1.09-1.34). Thus, the MS and DB cannot be used interchangeably. Whether the MS is suitable for evaluating ventilatory and pulmonary responses in swimming will depend on the size of effect required.

VO₂FITTING: A Free and Open-Source Software for Modelling Oxygen Uptake Kinetics in Swimming and other Exercise Modalities

The assessment of oxygen uptake (VO₂) kinetics is a valuable non-invasive way to evaluate cardiorespiratory and metabolic response to exercise. The aim of the study was to develop, describe and evaluate an online VO₂ fitting tool (VO₂FITTING) for dynamically editing, processing, filtering and modelling VO₂ responses to exercise. VO₂FITTING was developed in Shiny, a web application framework for R language. Validation VO₂ datasets with both noisy and non-noisy data were developed and applied to widely-used models (n = 7) for describing different intensity transitions to verify concurrent validity. Subsequently, we then conducted an experiment with age-group swimmers as an example, illustrating how VO₂FITTING can be used to model VO₂ kinetics. Perfect fits were observed, and parameter estimates perfectly matched the known inputted values for all available models (standard error = 0; p < 0.001). The VO₂FITTING is a valid, free and open-source software for characterizing VO₂ kinetics in exercise, which was developed to help the research and performance analysis communities.

Assessment of physical fitness and its correlates in Chinese children and adolescents in Shanghai using the multistage 20-M shuttle-run test

OBJECTIVE

The aim of this study was to evaluate the effectiveness of a multistage 20-m shuttle-run test (20-m SRT) in assessing the physical fitness of Chinese children and adolescents in Shanghai.

METHODS

A total of 4833 children and adolescents (2437 males and 2396 females, aged 7-17 years) were enrolled in this study. Height, weight, body fat percentage, fat-free mass, BMI, and skinfold thickness were measured or calculated. The participants were randomly grouped for performing the 20-m SRT. The maximal oxygen uptake (VO_2max and VO_2max/kg ) was estimated from the 20-m SRT using the model of Leger et al. RESULTS: All the measured and calculated parameters (age, height, weight, body fat percentage, fat-free mass, BMI, skinfold thickness, and the results of the 20-m SRT, as well as the estimated VO_2max and VO2_max/kg ) had significant correlations with each other (P < .05). The multiple regression analyses indicated that (1) results of the 20-m SRT were significantly associated with age, sex, height, and fat-free mass (P < .05); (2) VO_2max/kg was significantly associated with sex, age, weight, BMI, fat-free mass, and skinfold thickness (P < .001); and (3) VO_2max was markedly associated with sex, age, height, weight, BMI, fat-free mass, and skinfold thickness (P < .001). There were differences between males and females in the results of multiple regression analyses.

CONCLUSIONS

Results of the 20-m SRT and the estimated VO_2max and VO_2max/kg from the 20-m SRT can be used for evaluating the physical fitness of children and adolescents in Shanghai. Gender may be a factor affecting the effectiveness of the 20-m SRT.

Oxygen uptake kinetics and energy system's contribution around maximal lactate steady state swimming intensity

The purpose of this study was to examine the oxygen uptake (V˙O2) kinetics and the energy systems’ contribution at 97.5, 100 and 102.5% of the maximal lactate steady state (MLSS) swimming intensity. Ten elite female swimmers performed three-to-five 30 min submaximal constant swimming bouts at imposed paces for the determination of the swimming velocity (v) at 100%MLSS based on a 7 x 200 m intermittent incremental protocol until voluntary exhaustion to find the v associated at the individual anaerobic threshold. V˙O2 kinetics (cardiodynamic, primary and slow component phases) and the aerobic and anaerobic energy contributions were assessed during the continuous exercises, which the former was studied for the beginning and second phase of exercise. Subjects showed similar time delay (TD) (mean = 11.5–14.3 s) and time constant (τ_p) (mean = 13.8–16.3 s) as a function of v, but reduced amplitude of the primary component for 97.5% (35.7 ± 7.3 mL.kg.min^-1) compared to 100 and 102.5%MLSS (41.0 ± 7.0 and 41.3 ± 5.4 mL.kg.min^-1, respectively), and τ_p decreased (mean = 9.6–10.8 s) during the second phase of exercise. Despite the slow component did not occur for all swimmers at all swim intensities, when observed it tended to increase as a function of v. Moreover, the total energy contribution was almost exclusively aerobic (98–99%) at 97.5, 100 and 102.5%MLSS. We suggest that well-trained endurance swimmers with a fast TD and τ_p values may be able to adjust faster the physiological requirements to minimize the amplitude of the slow component appearance, parameter associated with the fatigue delay and increase in exhaustion time during performance, however, these fast adjustments were not able to control the progressive fatigue occurred slightly above MLSS, and most of swimmers reached exhaustion before 30min swam.

Sex and Exercise Intensity Do Not Influence Oxygen Uptake Kinetics in Submaximal Swimming

The aim of this study was to compare the oxygen uptake (V˙O2) kinetics in front crawl between male and female swimmers at moderate and heavy intensity. We hypothesized that the time constant for the primary phase V˙O2 kinetics was faster in men than in women, for both intensities. Nineteen well trained swimmers (8 females mean ± SD; age 17.9 ± 3.5 years; mass 55.2 ± 3.6 kg; height 1.66 ± 0.05 m and 11 male 21.9 ± 2.8 years; 78.2 ± 11.1 kg; 1.81 ± 0.08 m) performed a discontinuous maximal incremental test and two 600-m square wave transitions for both moderate and heavy intensities to determine the V˙O2 kinetics parameters using mono- and bi-exponential models, respectively. All the tests involved breath-by-breath analysis of front crawl swimming using a swimming snorkel. The maximal oxygen uptake (V˙O2max) was higher in men than in women [4,492 ± 585 ml·min⁻¹ and 57.7 ± 4.4 ml·kg⁻¹·min⁻¹ vs. 2,752.4 ± 187.9 ml·min⁻¹ (p ≤ 0.001) and 50.0 ± 5.7 ml·kg⁻¹·min⁻¹(p = 0.007), respectively]. Similarly, the absolute amplitude of the primary component was higher in men for both intensities (moderate: 1,736 ± 164 vs. 1,121 ± 149 ml·min⁻¹; heavy: 2,948 ± 227 vs. 1,927 ± 243 ml·min⁻¹, p ≤ 0.001, for males and females, respectively). However, the time constant of the primary component (τ_p) was not influenced by sex (p = 0.527) or swimming intensity (p = 0.804) (moderate: 15.1 ± 5.6 vs. 14.4 ± 5.1 s; heavy: 13.5 ± 3.3 vs. 16.0 ± 4.5 s, for females and males, respectively). The slow component in the heavy domain was not significantly different between female and male swimmers (3.2 ± 2.4 vs. 3.8 ± 1.0 ml·kg⁻¹·min⁻¹, p = 0.476). Overall, only the absolute amplitude of the primary component was higher in men, while the other V˙O2 kinetics parameters were similar between female and male swimmers at both moderate and heavy intensities. The mechanisms underlying these similarities remain unclear.

The effects of two different swimming training periodization on physiological parameters at various exercise intensities

This study analysed the effects of two different periodization strategies on physiological parameters at various exercise intensities in competitive swimmers. Seventeen athletes of both sexes were divided to two groups, the traditional periodization (TPG, n = 7) and the reverse periodization group (RPG, n = 10). Each group followed a 10-week training period based on the two different periodization strategies. Before and after training, swimming velocity (SV), energy expenditure (EE), energy cost (EC) and percentage of aerobic (%Aer) and anaerobic (%An) energy contribution to the swimming intensities corresponding to the aerobic threshold (AerT), the anaerobic threshold (AnT) and the velocity at maximal oxygen uptake (vVO₂max) were measured. Both groups increased the %An at the AerT and AnT intensity (P ≤ .05). In contrast, at the AnT intensity, EE and EC were only increased in TPG. Complementary, %Aer, %An, EE and EC at vVO₂max did not alter in both groups (P > .05); no changes were observed in SV in TPG and RPG at all three intensities. These results indicate that both periodization schemes confer almost analogous adaptations in specific physiological parameters in competitive swimmers. However, given the large difference in the total training volume between the two groups, it is suggested that the implementation of the reverse periodization model is an effective and time-efficient strategy to improve performance mainly for swimming events where the AnT is an important performance indicator.

Environmental influence on the prevalence and pattern of airway dysfunction in elite athletes

BACKGROUND AND OBJECTIVE

Elite swimming and boxing require athletes to achieve relatively high minute ventilation. The combination of a sustained high ventilation and provocative training environment may impact the susceptibility of athletes to exercise-induced bronchoconstriction (EIB). The purpose of this study was to evaluate the prevalence of EIB in elite Great British (GB) boxers and swimmers.

METHODS

Boxers (n = 38, mean age: 22.1 ± 3.1 years) and swimmers (n = 44, mean age: 21.1 ± 2.6 years) volunteered for the study. Athletes completed an exercise-induced respiratory symptom questionnaire, baseline assessment of fraction of exhaled nitric oxide (FeNO), maximal spirometry manoeuvres and a eucapnic voluntary hyperpnoea (EVH) challenge. EIB was confirmed if forced expiratory volume in 1 s (FEV₁ ) reduced by ≥10% from baseline at two time points post-EVH challenge.

RESULTS

The prevalence of EIB was greater in elite swimmers (30 of 44; 68%) than in boxers (3 of 38; 8%) (P < 0.001). Twenty-two out of the 33 (67%) EVH-positive athletes had no prior diagnosis of asthma/EIB. Moreover, 12% (6 of 49) of the EVH-negative athletes had a previous diagnosis of asthma/EIB. We found a correlation between FeNO and FEV₁ change in lung function post-EVH challenge in swimmers (r = 0.32; P = 0.04) but not in boxers (r = 0.24; P = 0.15).

CONCLUSION

The prevalence of EIB was ninefold greater in swimmers when compared with boxers. Athletes who train and compete in provocative environments at sustained high ventilation may have an increased susceptibility to EIB. It is not entirely clear whether increased susceptibility to EIB affects elite sporting performance and long-term airway health in elite athletes.

Ventilatory and Physiological Responses in Swimmers Below and Above Their Maximal Lactate Steady State

The purpose of this study was to understand the ventilatory and physiological responses immediately below and above the maximal lactate steady-state (MLSS) velocity and to determine the relationship of oxygen uptake (VO2) kinetics parameters with performance, in swimmers. Competitive athletes (N = 12) completed in random order and on different days a 400-m all-out test, an incremental step test comprising 5 × 250- and 1 × 200-m stages and 30 minutes at a constant swimming velocity (SV) at 87.5, 90, and 92.5% of the maximal aerobic velocity for MLSS velocity (MLSSv) determination. Two square-wave transitions of 500 m, 2.5% above and below the MLSSv were completed to determine VO2 on-kinetics. End-exercise VO2 at 97.5 and 102.5% of MLSSv represented, respectively, 81 and 97% of VO2max; the latter was not significantly different from maximal VO2 (VO2max). The VO2 at MLSSv (49.3 ± 9.2 ml·kg(-1)·min(-1)) was not significantly different from the second ventilatory threshold (VT2) (51.3 ± 7.6 ml·kg(-1)·min(-1)). The velocity associated with MLSS seems to be accurately estimated by the SV at VT2 (vVT2), and vVO2max also seems to be estimated with accuracy from the central 300-m mean velocity of a 400-m trial, indicators that represent a helpful tool for coaches. The 400-m swimming performance (T400) was correlated with the time constant of the primary phase VO2 kinetics (τp) at 97.5% MLSSv, and T800 was correlated with τp in both 97.5 and 102.5% of MLSSv. The assessment of the VO2 kinetics in swimming can help coaches to build training sets according to a swimmer's individual physiological response.

The oxygen uptake slow component at submaximal intensities in breaststroke swimming

The present work proposed to study the oxygen uptake slow component (VO2 SC) of breaststroke swimmers at four different intensities of submaximal exercise, via mathematical modeling of a multi-exponential function. The slow component (SC) was also assessed with two different fixed interval methods and the three methods were compared. Twelve male swimmers performed a test comprising four submaximal 300 m bouts at different intensities where all expired gases were collected breath by breath. Multi-exponential modeling showed values above 450 ml·min⁻¹ of the SC in the two last bouts of exercise (those with intensities above the lactate threshold). A significant effect of the method that was used to calculate the VO2 SC was revealed. Higher mean values were observed when using mathematical modeling compared with the fixed interval 3rd min method (F=7.111; p=0.012; η2=0.587); furthermore, differences were detected among the two fixed interval methods. No significant relationship was found between the SC determined by any method and the blood lactate measured at each of the four exercise intensities. In addition, no significant association between the SC and peak oxygen uptake was found. It was concluded that in trained breaststroke swimmers, the presence of the VO2 SC may be observed at intensities above that corresponding to the 3.5 mM-1 threshold. Moreover, mathematical modeling of the oxygen uptake on-kinetics tended to show a higher slow component as compared to fixed interval methods.

Underwater Near-Infrared Spectroscopy: Muscle Oxygen Changes in the Upper and Lower Extremities in Club Level Swimmers and Triathletes

To date, measurements of oxygen status during swim exercise have focused upon systemic aerobic capacity. The development of a portable, waterproof NIRS device makes possible a local measurement of muscle hemodynamics and oxygenation that could provide a novel insight into the physiological changes that occur during swim exercise. The purpose of this study was to observe changes in muscle oxygenation in the vastus lateralis (VL) and latissimus dorsi (LD) of club level swimmers and triathletes. Ten subjects, five club level swimmers and five club level triathletes (three men and seven women) were used for assessment. Swim group; mean±SD=age 21.2±1.6 years; height 170.6±7.5 cm; weight 62.8±6.9 kg; vastus lateralis skin fold 13.8±5.6 mm; latissimus dorsi skin fold 12.6±3.7. Triathlete group; mean±SD=age 44.0±10.5 years; height 171.6±7.0 cm; weight 68.6±12.7 kg; vastus lateralis skin fold 11.8±3.5 mm; latissimus dorsi skin fold 11.2±3.1. All subjects completed a maximal 200 m freestyle swim, with the PortaMon, a portable NIR device, attached to the subject's dominant side musculature. ΔTSI% between the vastus lateralis and latissimus dorsi were analysed using either paired (2-tailed) t-tests or Wilcoxon signed rank test. The level of significance for analysis was set at p<0.05. No significant difference (p=0.686) was found in ΔTSI (%) between the VL and LD in club level swimmers. A significant difference (p=0.043) was found in ΔTSI (%) between the VL and LD in club level triathletes. Club level swimmers completed the 200 m freestyle swim significantly faster (p=0.04) than club level triathletes. Club level swimmers use both the upper and lower muscles to a similar extent during a maximal 200 m swim. Club level triathletes predominately use the upper body for propulsion during the same exercise. The data produced by NIRS in this study are the first of their kind and provide insight into muscle oxygenation changes during swim exercise which can indicate the contribution of one muscle compared to another. This also enables a greater understanding of the differences in swimming techniques seen between different cohorts of swimmers and potentially within individual swimmers.

Airway dysfunction in elite swimmers: prevalence, impact, and challenges

The prevalence of airway dysfunction in elite swimmers is among the highest in elite athletes. The traditional view that swimmers naturally gravitate toward swimming because of preexisting respiratory disorders has been challenged. There is now sufficient evidence that the higher prevalence of bronchial tone disorders in elite swimmers is not the result of a natural selection bias. Rather, the combined effects of repeated chlorine by-product exposure and chronic endurance training can lead to airway dysfunction and atopy. This review will detail the underpinning causes of airway dysfunction observed in elite swimmers. It will also show that airway dysfunction does not prevent success in elite level swimming. Neither does it inhibit lung growth and might be partially reversible when elite swimmers retire from competition.

The effects of intensity on V̇O2 kinetics during incremental free swimming

Swimming and training are carried out with wide variability in distances and intensities. However, oxygen uptake kinetics for the intensities seen in swimming has not been reported. The purpose of this study was to assess and compare the oxygen uptake kinetics throughout low-moderate to severe intensities during incremental swimming exercise. We hypothesized that the oxygen uptake kinetic parameters would be affected by swimming intensity. Twenty male trained swimmers completed an incremental protocol of seven 200-m crawl swims to exhaustion (0.05 m·s(-1) increments and 30-s intervals). Oxygen uptake was continuously measured by a portable gas analyzer connected to a respiratory snorkel and valve system. Oxygen uptake kinetics was assessed using a double exponential regression model that yielded both fast and slow components of the response of oxygen uptake to exercise. From low-moderate to severe swimming intensities changes occurred for the first and second oxygen uptake amplitudes (P ≤ 0.04), time constants (P = 0.01), and time delays (P ≤ 0.02). At the heavy and severe intensities, a notable oxygen uptake slow component (>255 mL·min(-1)) occurred in all swimmers. Oxygen uptake kinetics whilst swimming at different intensities offers relevant information regarding cardiorespiratory and metabolic stress that might be useful for appropriate performance diagnosis and training prescription.

VO₂ kinetics and metabolic contributions during full and upper body extreme swimming intensity

PURPOSE

Our purpose was to characterize the oxygen uptake ([Formula: see text]) kinetics, assess the energy systems contributions and determine the energy cost when swimming front crawl at extreme intensity. Complementarily, we compared swimming full body with upper body only.

METHODS

Seventeen swimmers performed a 100 m maximal front crawl in two conditions: once swimming with full body and other using only the upper propulsive segments. The [Formula: see text] was continuously measured using a telemetric portable gas analyser (connected to a respiratory snorkel), and the capillary blood samples for lactate concentration analysis were collected.

RESULTS

A sudden increase in [Formula: see text] in the beginning of exercise, which continuously rose until the end of the bout (time: 63.82 ± 3.38 s; [Formula: see text]: 56.07 ± 5.19 ml min(-1) kg(-1); [Formula: see text] amplitude: 41.88 ± 4.74 ml min(-1) kg(-1); time constant: 12.73 ± 3.09 s), was observed. Aerobic, anaerobic lactic and alactic pathways were estimated and accounted for 43.4, 33.1 and 23.5 % of energy contribution and 1.16 ± 0.10 kJ m(-1) was the energy cost. Complementarily, the absence of lower limbs lead to a longer time to cover 100 m (71.96 ± 5.13 s), slower [Formula: see text] kinetics, lower aerobic and anaerobic (lactic and alactic) energy production and lower energy cost.

CONCLUSION

Despite the short duration of the event, the aerobic energy contribution covers about 50 % of total metabolic energy liberation, highlighting that both aerobic and anaerobic energy processes should be developed to improve the 100 m swimming performance. Lower limbs action provided an important contribution in the energy availability in working muscles being advised its full use in this short duration and very high-intensity event.

Underwater near-infrared spectroscopy measurements of muscle oxygenation: laboratory validation and preliminary observations in swimmers and triathletes

The purpose of this research was to waterproof a near-infrared spectroscopy device (PortaMon, Artinis Medical Systems) to enable NIR measurement during swim exercise. Candidate materials were initially tested for waterproof suitability by comparing light intensity values during phantom-based tissue assessment. Secondary assessment involved repeated isokinetic exercises ensuring reliability of the results obtained from the modified device. Tertiary assessment required analysis of the effect of water immersion and temperature upon device function. Initial testing revealed that merely covering the PortaMon light sources with waterproof materials considerably affected the NIR light intensities. Modifying a commercially available silicone covering through the addition of a polyvinyl chloride material (impermeable to NIR light transmission) produces an acceptable compromise. Bland–Altman analysis indicated that exercise-induced changes in tissue saturation index (TSI %) were within acceptable limits during laboratory exercise. Although water immersion had a small but significant effect upon NIR light intensity, this resulted in a negligible change in the measured TSI (%). We then tested the waterproof device in vivo illustrating oxygenation changes during a 100 m freestyle swim case study. Finally, a full study compared club level swimmers and triathletes. Significant changes in oxygenation profiles when comparing upper and lower extremities for the two groups were revealed, reflecting differences in swim biomechanics.

VO2 kinetics and metabolic contributions whilst swimming at 95, 100, and 105% of the velocity at VO2max

A bioenergetical analysis of swimming at intensities near competitive distances is inexistent. It was aimed to compare the transient VO₂ kinetics responses and metabolic contributions whilst swimming at different velocities around VO_2max⁡. 12 trained male swimmers performed (i) an incremental protocol to determine the velocity at VO_2max⁡ (vVO_2max⁡) and (ii) three square wave exercises from rest to 95, 100, and 105% of vVO_2max⁡. VO₂ was directly measured using a telemetric portable gas analyser and its kinetics analysed through a double-exponential model. Metabolic contributions were assessed through the sum of three energy components. No differences were observed in the fast component response (τ₁—15, 18, and 16 s, A₁—36, 34, and 37 mL · kg⁻¹ · min⁡⁻¹, and Gain—32, 29, and 30 mL · min⁡⁻¹ at 95, 100, and 105% of the vVO_2max⁡, resp.) but A2 was higher in 95 and 100% compared to 105% intensity (480.76 ± 247.01, 452.18 ± 217.04, and 147.04 ± 60.40 mL · min⁡⁻¹, resp.). The aerobic energy contribution increased with the time sustained (83 ± 5, 74 ± 6, and 59 ± 7% for 95, 100, and 105%, resp.). The adjustment of the cardiovascular and/or pulmonary systems that determine O₂ delivery and diffusion to the exercising muscles did not change with changing intensity, with the exception of VO₂ slow component kinetics metabolic profiles.

Critical Evaluation of Oxygen-Uptake Assessment in Swimming

Swimming has become an important area of sport science research since the 1970s, with the bioenergetic factors assuming a fundamental performance-influencing role. The purpose of this study was to conduct a critical evaluation of the literature concerning oxygen-uptake (VO2) assessment in swimming, by describing the equipment and methods used and emphasizing the recent works conducted in ecological conditions. Particularly in swimming, due to the inherent technical constraints imposed by swimming in a water environment, assessment of VO2max was not accomplished until the 1960s. Later, the development of automated portable measurement devices allowed VO2max to be assessed more easily, even in ecological swimming conditions, but few studies have been conducted in swimming-pool conditions with portable breath-by-breath telemetric systems. An inverse relationship exists between the velocity corresponding to VO2max and the time a swimmer can sustain it at this velocity. The energy cost of swimming varies according to its association with velocity variability. As, in the end, the supply of oxygen (whose limitation may be due to central—O2 delivery and transportation to the working muscles—or peripheral factors—O2 diffusion and utilization in the muscles) is one of the critical factors that determine swimming performance, VO2 kinetics and its maximal values are critical in understanding swimmers’ behavior in competition and to develop efficient training programs.

About the use and conclusions extracted from a single tube snorkel used for respiratory data acquisition during swimming

Pinna et al. (J Physiol Sci, 10.1007/s12576-012-0226-7, 2012) showed that a tethered swimming incremental protocol leads to higher maximal oxygen consumption values than during cycle ergometer and arm-crank tests, and evidenced that anaerobic threshold occurred at higher workloads during swimming comparing to other types of exercise. This is an interesting study in the field of exercise physiology applied to swimming that deserves merit once: (1) it employs direct gas exchange measurements during swimming, a rather hard task due to the characteristics of the water environment and the usual constraints imposed by the evaluation equipment, and (2) the physiologic comparison between swimming, running, cycling, and arm-cranking is complex, confirming that laboratory testing procedures are inadequate to estimate maximal oxygen consumption, maximal heart rate, and anaerobic threshold in swimming. However, in this Letter to the Editor, we would like to evidence some points that, in our opinion, are underdeveloped and not sufficiently clear, principally the incomplete description of the new breathing snorkel used, the non-reference to previous studies that used other snorkel models and obtained relevant data on oxygen uptake in swimming, and the assumption that swimmers uses less muscle mass when swimming than when running and cycling.

Assessment of the specificity of cardiopulmonary response during tethered swimming using a new snorkel device

This study aimed at comparing maximal oxygen uptake (VO(2max)), maximal heart rate (HR(max)), and anaerobic threshold (AT) obtained from tethered swimming (SW) and three other testing procedures: cycling (CY), running (RU), and arm cranking (AC). Variables were assessed in 12 trained male swimmers by a portable gas analyzer connected to a modified snorkel system to allow expired gases collection during swimming. Athletes exhibited a higher VO(2max) during the SW test as compared to the CY and the AC tests. There was no significant difference in VO(2max) between the SW and the RU test, but the Bland and Altman plot highlighted a poor agreement between results. Moreover, AT occurred at higher workloads during SW in comparison to the other tests. These results do not support the use of any unspecific testing procedures to estimate VO(2max), HR(max), and AT for swimming.

Reproducibility of an aerobic endurance test for nonexpert swimmers

Background:

This study aimed to verify the reproduction of an aerobic test to determine nonexpert swimmers’ resistance.

Methods:

The sample consisted of 24 male swimmers (age: 22.79 ± 3.90 years; weight: 74.72 ± 11.44 kg; height: 172.58 ± 4.99 cm; and fat percentage: 15.19% ± 3.21%), who swim for 1 hour three times a week. A new instrument was used in this study (a Progressive Swim Test): the swimmer wore an underwater MP3 player and increased their swimming speed on hearing a beep after every 25 meters. Each swimmer’s heart rate was recorded before the test (BHR) and again after the test (AHR). The rate of perceived exertion (RPE) and the number of laps performed (NLP) were also recorded. The sample size was estimated using G*Power software (v 3.0.10; Franz Faul, Kiel University, Kiel, Germany). The descriptive values were expressed as mean and standard deviation. After confirming the normality of the data using both the Shapiro–Wilk and Levene tests, a paired t-test was performed to compare the data. The Pearson’s linear correlation (r) and intraclass coefficient correlation (ICC) tests were used to determine relative reproducibility. The standard error of measurement (SEM) and the coefficient of variation (CV) were used to determine absolute reproducibility. The limits of agreement and the bias of the absolute and relative values between days were determined by Bland–Altman plots. All values had a significance level of P < 0.05.

Results:

There were significant differences in AHR (P = 0.03) and NLP (P = 0.01) between the 2 days of testing. The obtained values were r > 0.50 and ICC > 0.66. The SEM had a variation of ±2% and the CV was <10%. Most cases were within the upper and lower limits of Bland–Altman plots, suggesting correlation of the results. The applicability of NLP showed greater robustness (r and ICC > 0.90; SEM < 1%; CV < 3%), indicating that the other variables can be used to predict incremental changes in the physiological condition of swimmers.

Conclusion:

The Progressive Swim Test for nonexpert swimmers produces comparable results for noncompetitive swimmers with a favorable degree of reproducibility, thus presenting possible applications for researching the physiological performance of nonexpert swimmers.