This study illustrates the importance of inclusion minute ventilation data when comparing inhaled doses of air pollution between different population groups. This work has estimated for the first time the minute ventilation for different fitness classes. Also constitutes an important contribution for the assessment of inhaled dose in future studies to be performed in fitness centers.

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.

Purpose This study aims to analyze swimmers' oxygen uptake kinetics ( VO 2 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-VO 2 ) and maximal aerobic velocity (MAV) assessment. Maximal trials (MT) of 50, 100, and 200-m in front crawl swimming were performed for VO 2 K and bioenergetic profile. VO 2 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-VO 2 (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 VO 2 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 VO 2 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-VO 2 , and VO 2 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. VO 2 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. Keywords Oxygen uptake kinetics• Maximal trials • Swimming • Energy system contribution • Rate of adjustment of VO 2 Abbreviations % Percentage %MAV Percentage velocity to the MAV %Peak-VO 2 Percentage to the Peak-VO 2 τ Time constant [La − ] Blood lactate concentration ∆[La − ] Difference between rest and maximal [La − ] ∆ VO 2 /t VO 2 Growth rate A Amplitude Aer Aerobic AnaAlac Anaerobic alactic AnaLac Anaerobic lactic ANOVA Analysis of variance b Heart beats HR Heart rate ISD Individual snorkel delay K4b 2 Portable breath-by-breath gas analyzer kg Kilogram Communicated by I. Mark Olfert.