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

Physical performance determinants in competitive youth swimmers: a systematic review

BACKGROUND

Youth swimming performance is determined by several physiological, biomechanical and anthropometric characteristics. This review aimed to identify physical performance determinants of youth swimming performance, assessing strength, power, anaerobic, aerobic and body composition measures. ̇ METHODS: Searches were conducted in electronic databases (PubMed and Web of Science) using keywords relating to swimming and physiological measures, supplemented by citation searching of similar reviews. A total of 843 studies were identified in the initial search. The following inclusion criteria were used: participants were competitive/trained swimmers; swimming time-trial or event was conducted; data was provided on one or more physiological parameters; study was published in English and peer-reviewed. A total of 43 studies met the inclusion criteria. Risk of bias was assessed using Joanna Briggs Institute (JBI) checklist.

RESULTS

Cross-sectional studies scored between 4-8 and randomised-controlled trials scored 8-9 on their respective JBI checklists. Youth swimming performance was determined by muscle strength, muscle power, lean body mass, anaerobic and aerobic metabolism measures in most studies, where improved performance values of these variables were conducive to swimming performance. Body fat percentage did not have a clear relationship in youth swimming performance.

CONCLUSIONS

Findings of this review suggest that greater levels of muscle strength, muscle power and lean body mass are favourable in swimming performance, with muscle strength and muscle power particularly beneficial for start and turn performance. Anaerobic and aerobic metabolism measures were good determinants of swimming performance, with middle- and long-distance events more influenced by the latter. Body fat percentage has a nuanced relationship with swimming performance, where further investigation is required. Findings were inconsistent across studies, potentially due to unidentified confounding factors.

KEY POINTS

• Greater muscular strength and power qualities, anaerobic and aerobic capacities, and lean body mass are conducive to swimming performance. • Body fat percentage has a nuanced relationship with swimming performance. • Practitioners should consider general strength and power training as a useful tool to enhance performance in their youth competitors.

Stroke and physiological relationships during the incremental front crawl test: outcomes for planning and pacing aerobic training

Purpose: This study aimed to evaluate the physiological responses associated with the stroke length (SL) and stroke rate (SR) changes as swimming velocity increases during an incremental step-test. Moreover, this study also aimed to verify if SL and SR relationships toward maximal oxygen uptake (V̇O2max), gas respiratory compensation point (RCP), exchange threshold (GET), and swimming cost can be applied to the management of endurance training and control aerobic pace. Methods: A total of 19 swimmers performed the incremental test until volitional exhaustion, with each stage being designed by percentages of the 400 m (%v400) maximal front crawl velocity. V̇O2max, GET, RCP, and the respective swimming velocities (v) were examined. Also, the stroke parameters, SL, SR, the corresponding slopes (SLslope and SRslope), and the crossing point (Cp) between them were determined. Results: GET and RCP corresponded to 70.6% and 82.4% of V̇O2max (4185.3 ± 686.1 mL min-1), and V̇O2 at Cp, SLslope, and SRslope were observed at 129.7%, 75.3%, and 61.7% of V̇O2max, respectively. The swimming cost from the expected V̇O2 at vSLslope (0.85 ± 0.18 kJ m-1), vSRslope (0.77 ± 0.17 kJ m-1), and vCp (1.09 ± 0.19 kJ m-1) showed correlations with GET (r = 0.73, 0.57, and 0.59, respectively), but only the cost at vSLslope and vCp correlated to RCP (0.62 and 0.69) and V̇O2max (0.70 and 0.79). Conclusion: SL and SR exhibited a distinctive pattern for the V̇O2 response as swimming velocity increased. Furthermore, the influence of SL on GET, RCP, and V̇O2max suggests that SLslope serves as the metabolic reference of heavy exercise intensity, beyond which the stroke profile defines an exercise zone with high cost, which is recommended for an anaerobic threshold and aerobic power training. In turn, the observed difference between V̇O2 at SRslope and GET suggests that the range of velocities between SL and SR slopes ensures an economical pace, which might be recommended to develop long-term endurance. The results also highlighted that the swimming intensity paced at Cp would impose a high anaerobic demand, as it is located above the maximal aerobic velocity. Therefore, SLslope and SRslope are suitable indexes of submaximal to maximal aerobic paces, while Cp's meaning still requires further evidence.

Estimation of maximal lactate steady state using the sweat lactate sensor

A simple, non-invasive algorithm for maximal lactate steady state (MLSS) assessment has not been developed. We examined whether MLSS can be estimated from the sweat lactate threshold (sLT) using a novel sweat lactate sensor for healthy adults, with consideration of their exercise habits. Fifteen adults representing diverse fitness levels were recruited. Participants with/without exercise habits were defined as trained/untrained, respectively. Constant-load testing for 30 min at 110%, 115%, 120%, and 125% of sLT intensity was performed to determine MLSS. The tissue oxygenation index (TOI) of the thigh was also monitored. MLSS was not fully estimated from sLT, with 110%, 115%, 120%, and 125% of sLT in one, four, three, and seven participants, respectively. The MLSS based on sLT was higher in the trained group as compared to the untrained group. A total of 80% of trained participants had an MLSS of 120% or higher, while 75% of untrained participants had an MLSS of 115% or lower based on sLT. Furthermore, compared to untrained participants, trained participants continued constant-load exercise even if their TOI decreased below the resting baseline (P < 0.01). MLSS was successfully estimated using sLT, with 120% or more in trained participants and 115% or less in untrained participants. This suggests that trained individuals can continue exercising despite decreases in oxygen saturation in lower extremity skeletal muscles.

Oxygen Uptake Kinetics and Time Limit at Maximal Aerobic Workload in Tethered Swimming

This study aimed to apply an incremental tethered swimming test (ITT) with workloads (WL) based on individual rates of front crawl mean tethered force (Fmean) for the identification of the upper boundary of heavy exercise (by means of respiratory compensation point, RCP), and therefore to describe oxygen uptake kinetics (VO₂k) and time limit (t_Lim) responses to WL corresponding to peak oxygen uptake (WLVO_2peak). Sixteen swimmers of both sexes (17.6 ± 3.8 years old, 175.8 ± 9.2 cm, and 68.5 ± 10.6 kg) performed the ITT until exhaustion, attached to a weight-bearing pulley-rope system for the measurements of gas exchange threshold (GET), RCP, and VO_2peak. The WL was increased by 5% from 30 to 70% of Fmean at every minute, with Fmean being measured by a load cell attached to the swimmers during an all-out 30 s front crawl bout. The pulmonary gas exchange was sampled breath by breath, and the mathematical description of VO₂k used a first-order exponential with time delay (TD) on the average of two rest-to-work transitions at WLVO_2peak. The mean VO_2peak approached 50.2 ± 6.2 mL·kg^-1·min^-1 and GET and RCP attained (respectively) 67.4 ± 7.3% and 87.4 ± 3.4% VO_2peak. The average t_Lim was 329.5 ± 63.6 s for both sexes, and all swimmers attained VO_2peak (100.4 ± 3.8%) when considering the primary response of VO₂ (A_1' = 91.8 ± 6.7%VO_2peak) associated with the VO₂ slow component (SC) of 10.7 ± 6.7% of end-exercise VO₂, with time constants of 24.4 ± 9.8 s for A_1' and 149.3 ± 29.1 s for SC. Negative correlations were observed for t_Lim to VO_2peak, WLVO_2peak, GET, RCP, and EEVO₂ (r = -0.55, -0.59, -0.58, -0.53, and -0.50). Thus, the VO₂k during tethered swimming at WLVO_2peak reproduced the physiological responses corresponding to a severe domain. The findings also demonstrated that t_Lim was inversely related to aerobic conditioning indexes and to the ability to adjust oxidative metabolism to match target VO₂ demand during exercise.

Manipulation of Stroke Rate in Swimming: Effects on Oxygen Uptake Kinetics

The study aimed to assess the effect of different front crawl stroke rates (SRs) in the oxygen uptake (̇VO₂) kinetics and ̇VO₂ peak, the total time to exhaustion (TTE), and blood lactate concentration ([La]) at 95% of the 400-m front crawl test (T400) mean speed (S400). Twelve endurance swimmers performed a T400 and four trials at 95% of the S400: (i) free SR, (ii) fixed SR (100% of the average free SR trial), (iii) reduced SR (90% of the average free SR trial), and (iv) increased SR (110% of the average free SR trial). ̇VO₂ was accessed continuously with breath-by-breath analysis. The results highlighted: (i) the time constant at increased SR (13.3±4.2 s) was lower than in the reduced SR condition (19.5±2.6 s); (ii) the amplitude of the primary phase of ̇VO₂ kinetics in the fixed SR (44.0±5.8 ml·kg^-1·min^-1) was higher than in the increased SR condition (39.5±6.4 ml·kg^-1·min^-1); and (iii) TTE was lower in the fixed SR (396.1±189.7 s) than the increased SR condition (743.0±340.0 s). The results indicate that controlled SR could be considered a swimming training strategy, focusing on physiological parameters overload.

Time limit and V̇O2 kinetics at maximal aerobic velocity: Continuous vs. intermittent swimming trials

The time sustained during exercise with oxygen uptake (V̇O₂) reaching maximal rates (V̇O_2peak) or near peak responses (i.e., above second ventilatory threshold [t@VT₂) or 90% V̇O_2peak (t@90%V̇O_2peak)] is recognized as the training pace required to enhance aerobic power and exercise tolerance in the severe domain (time-limit, t_Lim). This study compared physiological and performance indexes during continuous and intermittent trials at maximal aerobic velocity (MAV) to analyze each exercise schedule, supporting their roles in conditioning planning. Twenty-two well-trained swimmers completed a discontinuous incremental step-test for V̇O_2peak, VT₂, and MAV assessments. Two other tests were performed in randomized order, to compare continuous (CT) vs. intermittent trials (IT₁₀₀) at MAV until exhaustion, to determine peak oxygen uptake (Peak-V̇O₂) and V̇O₂ kinetics (V̇O₂K). Distance and time variables were registered to determine the t_Lim, t@VT₂, and t@90%V̇O_2peak tests. Blood lactate concentration ([La⁻]) was analyzed, and rate of perceived exertion (RPE) was recorded. The tests were conducted using a breath-by-breath apparatus connected to a snorkel for pulmonary gas sampling, with pacing controlled by an underwater visual pacer. V̇O_2peak (55.2 ± 5.6 ml·kg·min⁻¹) was only reached in CT (100.7 ± 3.1 %V̇O_2peak). In addition, high V̇O₂ values were reached at IT₁₀₀ (96.4 ± 4.2 %V̇O_2peak). V̇O_2peak was highly correlated with Peak-V̇O₂ during CT (r = 0.95, p < 0.01) and IT₁₀₀ (r = 0.91, p < 0.01). Compared with CT, the IT₁₀₀ presented significantly higher values for t_Lim (1,013.6 ± 496.6 vs. 256.2 ± 60.3 s), distance (1,277.3 ± 638.1 vs. 315.9 ± 63.3 m), t@VT₂ (448.1 ± 211.1 vs. 144.1 ± 78.8 s), and t@90%V̇O_2peak (321.9 ± 208.7 vs. 127.5 ± 77.1 s). V̇O₂K time constants (IT₁₀₀: 25.9 ± 9.4 vs. CT: 26.5 ± 7.5 s) were correlated between tests (r = 0.76, p < 0.01). Between CT and IT₁₀₀, t_Lim were not related, and RPE (8.9 ± 0.9 vs. 9.4 ± 0.8) and [La⁻] (7.8 ± 2.7 vs. 7.8 ± 2.8 mmol·l⁻¹) did not differ between tests. MAV is suitable for planning swimming intensities requiring V̇O_2peak rates, whatever the exercise schedule (continuous or intermittent). Therefore, the results suggest IT₁₀₀ as a preferable training schedule rather than the CT for aerobic capacity training since IT₁₀₀ presented a significantly higher t_Lim, t@VT₂, and t@90%V̇O_2peak (∼757, ∼304, and ∼194 s more, respectively), without differing regards to [La⁻] and RPE. The V̇O₂K seemed not to influence t_Lim and times spent near V̇O_2peak in both workout modes.

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.

Can an Incremental Step Test Be Used for Maximal Lactate Steady State Determination in Swimming? Clues for Practice

We aimed to compare the velocity, physiological responses, and stroke mechanics between the lactate parameters determined in an incremental step test (IST) and maximal lactate steady state (MLSS). Fourteen well-trained male swimmers (16.8 ± 2.8 years) were timed for 400 m and 200 m (T₂₀₀). Afterwards, a 7 × 200-m front-crawl IST was performed. Swimming velocity, heart rate (HR), blood lactate concentration (BLC), stroke mechanics, and rate of perceived exertion (RPE) were measured throughout the IST and in the 30-min continuous test (CT) bouts for MLSS determination. Swimming velocities at lactate threshold determined with log-log methodology (1.34 ± 0.06 m∙s⁻¹) and Dmax methodology (1.40 ± 0.06 m∙s⁻¹); and also, the velocity at BLC of 4 mmol∙L⁻¹ (1.36 ± 0.07) were not significantly different from MLSSv, however, Bland–Altman analysis showed wide limits of agreement and the concordance correlation coefficient showed poor strength of agreement between the aforementioned parameters which precludes their interchangeable use. Stroke mechanics, HR, RPE, and BLC in MLSSv were not significantly different from the fourth repetition of IST (85% of T₂₀₀), which by itself can provide useful support to daily practice of well-trained swimmers. Nevertheless, the determination of MLSS_v, based on a CT, remains more accurate for exercise evaluation and prescription.

[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.

Comparison of Incremental Intermittent and Time Trial Testing in Age-Group Swimmers

Zacca, R, Azevedo, R, Peterson Silveira, R, Vilas-Boas, JP, Pyne, DB, Castro, FAdS, and Fernandes, RJ. Comparison of incremental intermittent and time trial testing in age-group swimmers. J Strength Cond Res 33(3): 801-810, 2019-The aim of this study was to compare physiological and biomechanical characteristics between an incremental intermittent test and a time trial protocol in age-group swimmers. Eleven national level age-group swimmers (6 men and 5 women) performed a 7 × 200-m incremental intermittent protocol (until exhaustion; 30-second rest) and a 400-m test (T400) in front crawl on separate days. Cardiorespiratory variables were measured continuously using a telemetric portable gas analyzer. Swimming speed, stroke rate, stroke length, and stroke index were assessed by video analysis. Physiological (oxygen uptake, heart rate, and lactate concentrations) and biomechanical variables between seventh 200-m step (in which the minimal swimming speed that elicits maximal oxygen uptake-vV[Combining Dot Above]O2max was identified) and T400 (time trial/fixed distance) were compared with a paired student's t test, Pearson's product-moment correlation, Passing-Bablok regression, and Bland-Altman plot analyses. There were high level of agreement and high correlations (r-values ∼0.90; p ≤ 0.05) for all physiological variables between the seventh 200-m step and T400. Similarly, there were high level of agreements and high correlations (r-values ∼0.90; p ≤ 0.05) for all biomechanical variables and only trivial bias in swimming speed (0.03 m·s; 2%). Primary physiological and biomechanical responses between incremental intermittent and representative time trial protocols were similar, but best practice dictates protocols should not be used interchangeably to minimize errors in prescribing swimming training speeds. The T400 is a valid, useful, and easier to administer test for aerobic power assessment in age-group swimmers.

A Rapidly-Incremented Tethered-Swimming Test for Defining Domain-Specific Training Zones

The purpose of this study was to investigate whether a tethered-swimming incremental test comprising small increases in resistive force applied every 60 seconds could delineate the isocapnic region during rapidly-incremented exercise. Sixteen competitive swimmers (male, n = 11; female, n = 5) performed: (a) a test to determine highest force during 30 seconds of all-out tethered swimming (F_avg) and the ΔF, which represented the difference between F_avg and the force required to maintain body alignment (F_base), and (b) an incremental test beginning with 60 seconds of tethered swimming against a load that exceeded F_base by 30% of ΔF followed by increments of 5% of ΔF every 60 seconds. This incremental test was continued until the limit of tolerance with pulmonary gas exchange (rates of oxygen uptake and carbon dioxide production) and ventilatory (rate of minute ventilation) data collected breath by breath. These data were subsequently analyzed to determine whether two breakpoints defining the isocapnic region (i.e., gas exchange threshold and respiratory compensation point) were present. We also determined the peak rate of O₂ uptake and exercise economy during the incremental test. The gas exchange threshold and respiratory compensation point were observed for each test such that the associated metabolic rates, which bound the heavy-intensity domain during constant-work-rate exercise, could be determined. Significant correlations (Spearman’s) were observed for exercise economy along with (a) peak rate of oxygen uptake (ρ = .562; p < 0.025), and (b) metabolic rate at gas exchange threshold (ρ = −.759; p < 0.005). A rapidly-incremented tethered-swimming test allows for determination of the metabolic rates that define zones for domain-specific constant-work-rate training.

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.