Anaerobic Contribution Research Articles

Third-Man-Passing Small-Sided Games Induce Higher Anaerobic Energy Contributions Than Regular-Passing Small-Sided Games in Football Players.

This study compared the physiological profiles and energy-system contributions of trained football players engaged in regular-passing and third-man-passing small-sided games (SSGs) that included 4 versus 4 and a goalkeeper. Ten maletrained football players participated in this crossover study. All participants were randomly assigned to either regular-passing SSG or third-man-passing SSG (4 vs 4 with a goalkeeper, 35-m × 17-m pitch size, and 6-min match duration). During these SSGs, physiological parameters including peak and mean heart rate, oxygen uptake (V˙O2peak and V˙O2mean), metabolic equivalents in V˙O2peak and V˙O2mean, and blood lactate concentrations (peak La- and delta La- [Δ La-]), were measured. Energy contributions (oxidative [WOxi], glycolytic [WGly], and phosphagen [WPCr] systems) and Global Positioning System (GPS)variables (total distance, total acceleration counts, mean speed, and maximum speed) were also analyzed. No significant differences in physiological parameters and GPS variables were found between regular- and third-man-passing SSGs. WOxi in kilojoules and percentages was significantly higher during both SSGs than WPCr and WGly (P < .0001, respectively). WPCr and WPCr + WGly values during third-man-passing SSGs were significantly higher than those during regular-passing SSGs (P < .05). Additionally, low to moderate positive correlations were observed between WOxi, WGly in kilojoules, V˙O2peak, V˙O2mean, peak La-, Δ La-, total acceleration counts, and mean speed (r = .39-.64). Third-man-passing SSGs may be useful for increasing anaerobic capacity. More third-man-passing SSG sessions in preparation for football games may support high metabolic power and repeated powerful anaerobic performances in trained football players.

An alternate to accumulated oxygen deficit (AOD) for measuring anaerobic contribution: 'AOD_alt' is valid in normoxia and hypoxia.

The gold standard measure of anaerobic contribution is accumulated oxygen deficit (AOD). The purpose of this study was to investigate the validity of an alternate measure, AOD_alt. AOD_alt is the sum of the phosphocreatine and glycolytic contributions, which are estimated from post-exercise oxygen uptake and blood lactate concentration, respectively. In Study One, six women and three men performed 6-min bouts of heavy intensity cycle ergometer exercise, once in normoxia (FIO2 ~ 21%) and twice under hypoxic conditions (FIO2 ~ 15% and ~ 12%). In Study Two, four women and two men performed severe intensity tests to exhaustion, once in normoxia (~ 10min) and twice in hypoxia (FIO2 ~ 15% and ~ 10%). Physiological responses were measured during exercise and 7min of recovery. In 6min of heavy exercise, Study One, the alternate and criterion measures of anaerobic contribution (AOD_alt and AOD) were correlated, in normoxia and in hypoxia. In exhaustive severe exercise, Study Two, AOD_alt and AOD were correlated (r = 0.77) and similar, in normoxia and at FIO2 ~ 15%. However, AOD_alt and AOD values were neither correlated (r = 0.27) nor similar (57 ± 5mL·kg-1 vs 51 ± 7mL·kg-1) at FIO2 ~ 10%. These results confirm the validity of AOD_alt as a measure of anaerobic capacity in severe intensity exercise, demonstrate its validity in heavy exercise, and assert its validity in conditions of hypoxia (FIO2 ~ 12%).

An empirical model for world record running speeds with distance, age, and sex: anaerobic and aerobic contributions to performance.

The objective of this study is to derive mathematical equations that closely describe published data on world record running speed as a function of distance, age, and sex. Running speed declines with increasing distance and age. Over long distances, where aerobic metabolism is dominant, speed declines in proportion to the logarithm of distance. Over short distances, anaerobic metabolism contributes significantly to performance, and speed is increased relative to the trend of the long-distance data. Equations are derived that explicitly represent these effects. The decline in speed with age is represented by an age-dependent multiplicative factor, which exhibits increasing sensitivity to age as age increases. Using these equations, data are analyzed separately for males and females, and close fits to published data are demonstrated, particularly for younger age groups. These equations provide insight into the contributions of aerobic and anaerobic components of metabolism to athletic performance and a framework for comparisons of performance across wide ranges of distance and age.NEW & NOTEWORTHY World record speeds at different distances for men and women in different age categories are used to develop a model to predict running performance as a function of race distance, age, and sex. This empirical model quantifies the decline in running speed with distance and age in a way that provides insight into the aerobic and anaerobic contributions to running speed and may help with developing training strategies for different age groups at various distances.

Field-training in young two-year-old thoroughbreds: investigating cardiorespiratory adaptations and the presence of exercise induced pulmonary hemorrhage

BackgroundComparatively little is known regarding the initial cardiorespiratory response of young racehorses to training. The objectives were to compare physiological parameters before and after introductory training and determine whether young Thoroughbreds show endoscopic signs of exercise-induced pulmonary hemorrhage (EIPH). Ten Thoroughbreds (20–23 months) underwent 12-weeks of introductory training, including weekly speed sessions. Two 600 m high-speed exercise tests (HSET) were performed following weeks 4 and 12 while wearing a validated ergospirometry facemask. Peak oxygen consumption (V̇O2pk) and ventilatory parameters (tidal volume, VT; peak inspiratory and expiratory flow, PkV̇I, PkV̇E; respiratory frequency, Rf; minute ventilation, V̇E) were measured. The ventilatory equivalent of oxygen (V̇E/V̇O2) and the aerobic and anaerobic contributions to energy production were calculated. Maximal heart rate (HRmax) and HR at maximal speed (HRVmax) were determined. Post-exercise hematocrit, plasma ammonia and blood lactate were measured. Evidence of EIPH was investigated via tracheobronchoscopy post-exercise. Results were compared (paired t-test, P < 0.05).ResultsHorses were faster following training (P < 0.001) and V̇O2pk increased 28 ml/(kg total mass.min) (28 ± 16%; P < 0.001). Ventilatory (V̇E, P = 0.0015; Rf, P < 0.001; PkV̇I, P < 0.001; PkV̇E, P < 0.001) and cardiovascular parameters (HRmax, P = 0.03; HRVmax, P = 0.04) increased. The increase in V̇E was due to greater Rf, but not VT. V̇E/V̇O2 was lower (26 ± 3.6 vs 23 ± 3.7; P = 0.02), indicating improved ventilatory efficiency. Anaerobic contribution to total energy production increased from 15.6 ± 6.1% to 18.5 ± 6.3% (P = 0.02). Post-exercise hematocrit (P < 0.001), plasma ammonia (P = 0.03) and blood lactate (P = 0.001) increased following training. Horses showed no signs of EIPH.ConclusionsYoung two-year-old Thoroughbreds responded well to introductory training without developing tracheobronchoscopic evidence of EIPH.

Modelling the optimization of world-class 400 m and 1,500 m running performances using high-resolution data.

The 400 m and 1,500 m are track events that rely on different but important contributions from both the aerobic and anaerobic energy systems. The purpose of this study is to model men's and women's 400 m and 1,500 m championship performances to gain a deeper understanding of the key mechanical and physiological factors affecting running speed and bend running using high-resolution data from live competition (10 Hz). To investigate World-class athletes' instantaneous speeds, propulsive forces and aerobic and anaerobic energy, we model and simulate the performances of the men's and women's European Athletics 400 m champions, Matthew Hudson-Smith and Femke Bol, as well as the men's European Athletics 1,500 m champion, Jakob Ingebrigtsen, and the women's European Athletics U23 1,500 m champion, Gaia Sabbatini. The simulations show that a fast start is essential in both the 400 m and 1,500 m because of the need for fast oxygen kinetics, with peak running speeds occurring within the first ∼50 m in both events. Subsequently, 400 m athletes slow continually from this maximum speed to the finish, and a total anaerobic contribution of ∼77% is found for both male and female champions. The key to faster 400 m racing is to reduce the decrease in velocity: this comes from both a high VO2 and a high anaerobic contribution. Ingebrigtsen's winning tactic in the European 1,500 m final is to adopt a very fast cruising pace from 300 m onwards that is possible because he is able to maintain a high VO2 value until the end of the race and has a large anaerobic contribution. He has fast VO2 kinetics that does not require as fast a start as his opponents, but then he speeds up in the last two laps, without a fast sprint finish. The comparison between Sabbatini's slower and quicker races (∼8 s difference) shows that it is the improvement of aerobic metabolism that has the greatest effect on 1,500 m performance. Coaches should note in particular that the all-out pacing nature of the 400 m requires the prioritization of anaerobic energy system development, and those who coach the 1,500 m should note the differing energy contributions between even-paced races and championship racing.

Energy conservation by collective movement in schooling fish

Many animals moving through fluids exhibit highly coordinated group movement that is thought to reduce the cost of locomotion. However, direct energetic measurements demonstrating the energy-saving benefits of fluid-mediated collective movements remain elusive. By characterizing both aerobic and anaerobic metabolic energy contributions in schools of giant danio (Devario aequipinnatus), we discovered that fish schools have a concave upward shaped metabolism–speed curve, with a minimum metabolic cost at ~1 body length s-1. We demonstrate that fish schools reduce total energy expenditure (TEE) per tail beat by up to 56% compared to solitary fish. When reaching their maximum sustained swimming speed, fish swimming in schools had a 44% higher maximum aerobic performance and used 65% less non-aerobic energy compared to solitary individuals, which lowered the TEE and total cost of transport by up to 53%, near the lowest recorded for any aquatic organism. Fish in schools also recovered from exercise 43% faster than solitary fish. The non-aerobic energetic savings that occur when fish in schools actively swim at high speed can considerably improve both peak and repeated performance which is likely to be beneficial for evading predators. These energetic savings may underlie the prevalence of coordinated group locomotion in fishes.

Energy conservation by collective movement in schooling fish.

Many animals moving through fluids exhibit highly coordinated group movement that is thought to reduce the cost of locomotion. However, direct energetic measurements demonstrating the energy-saving benefits of fluid-mediated collective movements remain elusive. By characterizing both aerobic and anaerobic metabolic energy contributions in schools of giant danio (Devario aequipinnatus), we discovered that fish schools have a concave upward shaped metabolism-speed curve, with a minimum metabolic cost at ~1 body length s-1. We demonstrate that fish schools reduce total energy expenditure (TEE) per tail beat by up to 56% compared to solitary fish. When reaching their maximum sustained swimming speed, fish swimming in schools had a 44% higher maximum aerobic performance and used 65% less non-aerobic energy compared to solitary individuals, which lowered the TEE and total cost of transport by up to 53%, near the lowest recorded for any aquatic organism. Fish in schools also recovered from exercise 43% faster than solitary fish. The non-aerobic energetic savings that occur when fish in schools actively swim at high speed can considerably improve both peak and repeated performance which is likely to be beneficial for evading predators. These energetic savings may underlie the prevalence of coordinated group locomotion in fishes.

Reliability of Anaerobic Contributions during a Single Exhaustive Knee-extensor Exercise.

The total anaerobic contribution (AC[La-]+PCr) is a valid and reliable methodology. However, the active muscle mass plays an important role in the AC[La-]+PCr determination, which might influence its reliability. Thus, this study aimed to investigate the effects of two exhaustive intensities on the reliability of the AC[La-]+PCr during a one-legged knee extension (1L-KE) exercise. Thirteen physically active males were submitted to a graded exercise to determine the peak power output (PPO) in the 1L-KE. Then, two constant-load exercises were conducted to task failure at 100% (TTF100) and 110% (TTF110) of PPO, and the exercises were repeated on a third day. The blood lactate accumulation and the oxygen uptake after exercise were used to estimate the anaerobic lactic and alactic contributions, respectively. Higher values of AC[La-]+PCr were found after the TTF100 compared to TTF110 (p=0.042). In addition, no significant differences (p=0.432), low systematic error (80.9 mL), and a significant ICC (0.71; p=0.004) were found for AC[La-]+PCr in the TTF100. However, an elevated coefficient of variation was found (13.7%). In conclusion, we suggest the use of the exhaustive efforts performed at 100% of the PPO with the 1L-KE model, but its elevated individual variability must be carefully considered in future studies.

A 6-Week Ketogenic Diet Enhances the Phosphocreatine Energy System Contribution During Intermittent Sprints

Abstract Purpose Team sports often involve intermittent sprints. During these activities the Phosphocreatine-ATP buffer (ATP-PCr) signifies the major anaerobic energy substrate. While the effects of ketogenic diets (KD) on carbohydrate and fat metabolism during endurance exercise are widely reported, we explored keto-adaptation in ATP-PCr metabolism during intermittent sprint exercise. Methods Following a within-subject repeated measures design, 15 recreationally active participants (7 men, 8 women, aged 25.1 ± 6.4 years) performed cycle ergometer intermittent sprints (6 × 10 s sprints, 2 min recovery) with VO2 and blood lactate measurements for energy system calculations. These laboratory tests were performed in alternate weeks; First, twice at baseline on their habitual diet (HD) (35% CHO, 45% fat, 20% protein) and thereafter over a 6-week KD (7% CHO, 66% fat, 28% protein). Results Repeated measures ANOVA’s and Bonferroni tests revealed ATP-PCr derived energy increased significantly from HD to KD week 6 (+ 22.0 ± 43.15 J; P = 0.019; ES = 0.47). From HD to KD week 2, anaerobic glycolytic contribution lowered (− 14.4 ± 28.16 J; P = 0.031; ES = − 0.10) and peak blood [lactate] reduced significantly (− 2.92 ± 0.851 mmol; P = 0.004; ES = − 0.73). There was no statistically significant within-subject change in mean sprint power (P = 0.356). Conclusion The 6-week KD did not compromise intermittent sprint performance. The findings suggest that the ATP-PCr energy pathway may be a novel site of metabolic keto-adaptation. This, combined with the lowered blood [lactate] we observed, presents desirable metabolic adaptations for intermittent sprint sport athletes.

Shifting the Energy Toward Los Angeles: Comparing the Energetic Contribution and Pacing Approach Between 2000- and 1500-m Maximal Ergometer Rowing.

To compare the energetic contribution and pacing in 2000- and 1500-m maximal rowing-ergometer performances. On separate visits (>48 h apart, random order), 18 trained junior (16.7 [0.4]y) male rowers completed 3 trials: a7 × 4-minute graded exercise test, a2000-m time trial (TT2000), and a1500-m TT (TT1500). Respiratory gases were continuously measured throughout each trial. The submaximal power-to-oxygen-consumption relationship from the graded exercise test was used to determine the accumulated oxygen deficit for each TT. Differences in mean power output (MPO), relative anaerobic contribution, percentage of peak oxygen uptake, pacing index, maximum heart rate, rating of perceived exertion, and blood lactate concentration were assessed using linear mixed modeling. Compared to TT2000 (324 [24]W), MPO was 5.2% (3.3%) higher in TT1500 (341 [29W]; P < .001, ηp2=.70). There was a 4.9% (3.3%) increase (P < .001, ηp2=.71) in anaerobic contribution from 17.3% (3.3%) (TT2000) to 22.2% (4.3%) (TT1500). Compared to TT1500, maximum heart rate, rating of perceived exertion, and blood lactate concentration were all greater (P < .05) in TT2000. The pacing index was not different between trials. Percentage increase in MPO from TT2000 to TT1500 was negatively associated with pacing variance in TT1500 (R2 = .269, P = .027). Maximal ergometer performance over 1500m requires a significantly greater anaerobic contribution compared with 2000m. Junior male athletes adopt a consistent pacing strategy across both distances. However, those who experienced greater percentage increases in MPO over the shorter test adopted a more even pacing strategy. To prepare for 1500-m performance, greater emphasis should be placed on developing capacity for work in thesevere domain and completing race simulations with a more even pacing strategy.

Energetics of sinusoidal exercise below and across critical power and the effects of fatigue

PurposePrevious studies investigating sinusoidal exercise were not devoted to an analysis of its energetics and of the effects of fatigue. We aimed to determine the contribution of aerobic and anaerobic lactic metabolism to the energy balance and investigate the fatigue effects on the cardiorespiratory and metabolic responses to sinusoidal protocols, across and below critical power (CP).MethodsEight males (26.6 ± 6.2 years; 75.6 ± 8.7 kg; maximum oxygen uptake 52.8 ± 7.9 ml·min−1·kg−1; CP 218 ± 13 W) underwent exhausting sinusoidal cycloergometric exercises, with sinusoid midpoint (MP) at CP (CPex) and 50 W below CP (CP-50ex). Sinusoid amplitude (AMP) and period were 50 W and 4 min, respectively. MP, AMP, and time-delay (tD) between mechanical and metabolic signals of expiratory ventilation (V˙E\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\dot{V}}_{E}$$\\end{document}), oxygen uptake (V˙O2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\dot{V}}_{{{\ ext{O}}}_{2}}$$\\end{document}), and heart rate (fH\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${f}_{H}$$\\end{document}) were assessed sinusoid-by-sinusoid. Blood lactate ([La−]) and rate of perceived exertion (RPE) were determined at each sinusoid.ResultsV˙O2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\dot{V}}_{{{\ ext{O}}}_{2}}$$\\end{document} AMP was 304 ± 11 and 488 ± 36 ml·min−1 in CPex and CP-50ex, respectively. Asymmetries between rising and declining sinusoid phases occurred in CPex (36.1 ± 7.7 vs. 41.4 ± 9.7 s for V˙O2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\dot{V}}_{{{\ ext{O}}}_{2}}$$\\end{document}tD up and tD down, respectively; P < 0.01), with unchanged tDs. V˙O2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\dot{V}}_{{{\ ext{O}}}_{2}}$$\\end{document} MP and RPE increased progressively during CPex. [La−] increased by 2.1 mM in CPex but remained stable during CP-50ex. Anaerobic contribution was larger in CPex than CP-50ex.ConclusionThe lower aerobic component during CPex than CP-50ex associated with lactate accumulation explained lower V˙O2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\dot{V}}_{{{\ ext{O}}}_{2}}$$\\end{document} AMP in CPex. The asymmetries in CPex suggest progressive decline of muscle phosphocreatine concentration, leading to fatigue, as witnessed by RPE.

Determining Physiological and Energetic Demands during High-Level Pommel Horse Routines Using a Modified Method Based on Heart Rate-Oxygen Uptake Functions.

This study aimed (1) to assess the validity of a modified method (Mmod) based on heart rate (HR)-oxygen uptake (VO2) regression functions to calculate total energy costs (Wtotal) and aerobic (Waer) and anaerobic alactic energy contribution (Wpcr) and (2) to analyse the physiological and energetic demands of high-level pommel horse routines (PH routines). The Mmod was developed because VO2 measurements are limited during high-level PH routines. Answering Part 1, nine male artistic gymnasts performed a PH routine where energy costs were calculated from VO2 measurements and then compared with energy costs determined from the HR- VO2 regressions of Mmod's two additional tests. Using the concordance correlation coefficient (CCC) and Deming regression, Waer (CCC = 0.955), Wpcr (CCC = 0.999), and Wtotal (CCC = 0.990) show substantial to almost perfect validity without constant or proportional bias. Data from eight further gymnasts performing a high-level PH routine and a graded exercise test (GXT), as well as four data sets from Part 1, were used to determine physiological and energetic demands using Mmod. VO2 and HR during PH routines reached 86.1% and 90.4% of the maximal values during GXT. Wpcr was 47.0%, anaerobic lactic energy contribution (Wblc) was 29.7%, and Waer was 23.3% of Wtotal required during PH routines. Summarising the energetic demands of high-level PH routines, they are mainly anaerobic, where Wpcr provides the largest energy share. Waer provides a substantial part of Wtotal and should therefore also be specifically trained.

Changes in roller skiing economy among Nordic combined athletes leading up to the competition season.

The purpose of this study was to compare roller skiing economy during different training phases in Nordic combined (NC) athletes and determine the aerobic and anaerobic factors responsible for changes in skiing economy. Seven elite NC athletes underwent incremental load tests on a large buried treadmill in both spring and autumn using roller skis. Measurements included oxygen uptake, respiratory exchange ratio, and blood lactate concentration. Roller skiing economy was calculated from aerobic and anaerobic energy system contributions, and overall roller skiing economy was determined by combining the two. Comparisons were made between the skiing economies obtained in the two measurement sessions. Physical characteristics and incremental test performance remained consistent between the two measurement sessions. The overall skiing economy at each speed significantly improved toward the competition season (p < 0.05). Similarly, the contribution of anaerobic energy system at each speed showed significant improvement (p < 0.05). In contrast, the contribution of aerobic energy system did not change between the two measurement sessions. This study reveals that NC athletes enhance their skiing economy at the same speed during submaximal efforts in preparation for the competition season. This improvement is predominantly associated with an improvement in the contribution of anaerobic energy system.

Anaerobic and aerobic contributions to repeated supramaximal cycling exercises and their adaptation to high-intensity interval training in obese perimenopausal and postmenopausal women.

This study investigated the anaerobic and aerobic contributions to total energy release during repeated supramaximal cycling exercises (SCE) and their adaptation in response to 6 weeks of high-intensity interval training (HIIT) in obese perimenopausal and postmenopausal women. Nineteen perimenopausal women and 21 postmenopausal women with an average age of 50.1 years participated in the 6-week HIIT intervention. Before and after the training, the accumulated oxygen deficits (mL·min -1 ) and anaerobic and aerobic contributions (%) were measured in all groups via repeated SCE. The results showed that, before training, the anaerobic contributions to repeated SCE did not differ between the perimenopausal and postmenopausal women for the first three repetitions. However, a higher decrease was reported for postmenopausal women at the fourth and fifth repetitions ( P < 0.01, respectively). After HIIT, anaerobic contributions increased significantly in both groups ( P < 0.01, respectively). Nevertheless, postmenopausal women still had significantly lower anaerobic contributions to repeated SCE compared with perimenopausal women ( P < 0.01, respectively). Multiple linear regression analysis indicated that menopause status was an independent predictor of anaerobic contribution, accounting for 17%, 21%, 15%, 19%, and 22% of variations (β = 0.28, P = 0.03; β = 0.29, P = 0.04; β = 0.18, P = 0.05; β = 0.22, P = 0.05; and β = 0.33, P = 0.03 for the first to the fifth repetitions consecutively for perimenopausal vs postmenopausal groups). A 6-week HIIT intervention increased the anaerobic contributions to energy in response to repeated SCE in obese perimenopausal and postmenopausal women. However, postmenopausal women had lower anaerobic contributions at the fourth and fifth repetitions mainly due to the effects of menopause.

Determinants of 1500-m Front-Crawl Swimming Performance in Triathletes: Influence of Physiological and Biomechanical Variables.

To analyze the associations between physiological and biomechanical variables with the FINA (International Swimming Federation)points (ie,swimming performance) obtained in 1500-m front-crawl swimming to determine whether these variables can be used to explain triathletes' FINA points. Fourteen world-class, international and national triathletes (10 male: 23.24 [3.70]y and 4 female: 23.36 [3.76]y) performed a 1500-m front-crawl swimming test in a short-course pool. Heart rate (HR), oxygen uptake (V˙O2), and blood lactate concentrations were obtained before and after the test. HR was also measured during the effort. Highest V˙O2 value (V˙O2peak) was estimated by extrapolation. Clean swimming speed, turn performance, stroke rate, stroke length, and stroke index (SI) were obtained by video analysis. Average 1500-m performance times were 1088 (45)seconds and 1144 (31)seconds for males and females, respectively. HR after the effort, V˙O2peak, aerobic contributions, total energyexpenditure, energy cost, and turn performance presented moderate negative associations with swimming performance (r ≈ .5). In contrast, respiratory exchange ratio, anaerobic alactic contribution, clean swimming speed, stroke length, and SI were positively related, with clean swimming speed and SI havinga strong large association (r ≈ .7). A multiple stepwise regression model determined that 71% of thevariance in FINA points was explained by SI and total energy expenditure, being predictors in 1500-m front-crawl swimming. Swimming performance in triathletes was determined by the athletes' energy demands and biomechanical variables. Thus, coaches should develop specific technique skills to improve triathletes' swimming efficiency.

Bioenergetic Analysis and Fatigue Assessment During the Fran Workout in Experienced Crossfitters.

To quantify the physiological demands and impact of muscle function t of the Fran workout, one of the most popular CrossFit benchmarks. Twentyexperienced CrossFitters-16 male: 29 (6)years old and 4 female: 26 (5)years old- performed 3 rounds (with 30-s rests in between) of 21-21, 15-15, and 9-9 front squats to overhead press plus pull-up repetitions. Oxygen uptake and heart rate were measured at baseline, during the workout, and in the recovery period. Rating of perceived exertion, blood lactate, and glucose concentrations were assessed at rest, during the intervals, and in the recovery period. Muscular fatigue was also monitored at rest and at 5 minutes, 30 minutes, and 24 hours postexercise. Repeated-measures analysis of variancewas performed to compare time points. Aerobic (52%-29%) and anaerobic alactic (30%-23%) energy contributions decreased and the anaerobic lactic contribution increased (18%-48%) across the 3 rounds of the Fran workout. Countermovement jump height decreased by 8% (-12 to -3) mean change (95% CI), flight duration by 14% (-19 to -7), maximum velocity by 3% (-5 to -0.1), peak force 4% (-7 to -0.1), and physical performance (plank prone 47% [-54 to -38]) were observed. It appears that the Fran workout is a physically demanding activity that recruits energy from both aerobic and anaerobic systems. This severe-intensity workout evokes substantial postexercise fatigue and corresponding reduction in muscle function.

Determination, measurement, and validation of maximal aerobic speed

This study determined Maximal Aerobic Speed (MAS) at a speed that utilizes maximal aerobic and minimal anaerobic contributions. This method of determining MAS was compared between endurance (ET) and sprint (ST) trained athletes. Nineteen and 21 healthy participants were selected for the determination and validation of MAS respectively. All athletes completed five exercise sessions in the laboratory. Participants validating MAS also ran an all-out 5000 m at the track. Oxygen uptake at MAS was at 96.09 ± 2.51% maximal oxygen consumption ({{dot{rm{V}}}}text{O}_{text{2max}}). MAS had a significantly higher correlation with velocity at lactate threshold (vLT), critical speed, 5000 m, time-to-exhaustion velocity at delta 50 in addition to 5% velocity at {{dot{rm{V}}}}text{O}_{text{2max}} (TlimυΔ50 + 5%v{{dot{rm{V}}}}text{O}_{text{2max}}), and Vsub%95 (υΔ50 or υΔ50 + 5%v{{dot{rm{V}}}}text{O}_{text{2max}}) compared with v{{dot{rm{V}}}}text{O}_{text{2max}}, and predicted 5000 m speed (R2 = 0.90, p < 0.001) and vLT (R2 = 0.96, p < 0.001). ET athletes achieved significantly higher MAS (16.07 ± 1.58 km·h−1 vs. 12.77 ± 0.81 km·h−1, p ≤ 0.001) and maximal aerobic energy (EMAS) (52.87 ± 5.35 ml·kg−1·min−1 vs. 46.42 ± 3.38 ml·kg−1·min−1, p = 0.005) and significantly shorter duration at MAS (ET: 678.59 ± 165.44 s; ST: 840.28 ± 164.97 s, p = 0.039). ST athletes had significantly higher maximal speed (35.21 ± 1.90 km·h−1, p < 0.001) at a significantly longer distance (41.05 ± 3.14 m, p = 0.003) in the 50 m sprint run test. Significant differences were also observed in 50 m sprint performance (p < 0.001), and peak post-exercise blood lactate (p = 0.005). This study demonstrates that MAS is more accurate at a percentage of v{{dot{rm{V}}}}text{O}_{text{2max}} than at v{{dot{rm{V}}}}text{O}_{text{2max}}. The accurate calculation of MAS can be used to predict running performances with lower errors (Running Energy Reserve Index Paper).

Aerobic and Anaerobic Energy Contributions during Short-Duration Supramaximal Exercises with Different Exercise Intensities

The study examined the relative energy contributions during 60-s supramaximal exercise with different exercise intensities. Nine male track and field sprinters performed a 60-s Wingate anaerobic test and a 60-s cycling tests at five intensities of 55%, 65%, 75%, 85%, and 95% mean power of the Wingate anaerobic test. The relative contributions of aerobic and anaerobic energy during the 60-s cycling tests were estimated by the ratio of O2 uptake and O2 deficit, the latter being calculated as the difference between O2 demand and O2 uptake. %VO2max of the 60-s cycling tests ranged from 100 ± 7 to 163 ± 11%VO2max. As exercise intensity increased, O2 uptake, O2 deficit, and anaerobic energy contributions during the 60-s cycling tests increased (p < 0.05). In contrast, in the first ~40 s during the 60-s cycling, the anaerobic energy contributions were not significant differences between each intensity. O2 uptake per 10 s increased with time course till 40 or 50 s in each intensity (p < 0.05). The different results of these at the first ～40 and 60 s during the 60-s cycling tests could be attributed to the insufficient increase in O2 uptake during the last 20 s of the test. These results suggest that, as exercise intensity increases, the anaerobic energy contribution becomes more prominent in the latter half of the 60-s exercise (i.e., 50 and 60 s) compared to the first 30 and 40 s.

Pros and Cons of Two Methods of Anaerobic Alactic Energy Assessment in a High-Intensity CrossFit® Workout

The current study aimed to evidence the strengths and weaknesses of two indirect methods for assessing the anaerobic alactic contribution to a specific CrossFit® workout. Thirty experienced crossfitters performed the Fran workout at maximal intensity, and ventilatory data were collected during the recovery period using a telemetric portable gas analyser to assess the oxygen uptake (VO2) of the off-kinetics fast component (Anarecovery). The kinetics of maximal phosphocreatine splitting (AnaPCr) were determined based on the literature. No differences between the two methods were observed (31.4 ± 4.0 vs. 30.4 ± 4.1 kJ for Anarecovery and AnaPCr, respectively). Despite the existence of some caveats (e.g., errors derived from a delay at the onset of VO2 recovery and the assumption of given values in the concentration of phosphocreatine per kilogram of wet muscle, respectively) in both methods, the data indicate that they yield similar results and allow for estimations of alactic energy contribution from a short-duration and high intensity CrossFit® routine. The current data contributes to CrossFit® workout evaluations and training strategies, helping researchers to evaluate crossfitters more accurately. The advantage of the two methods used in the current study is that they are non-invasive, which differs greatly from muscle biopsies.

Physiological Responses and Performance During a 3-Minute Cycle Time Trial: Standard Paced Versus All-Out Paced.

To compare performance and physiological responses between a standard-paced 3-minute time trial (TTSP, ie,pacing based on normal intention) and a consistently all-out-paced 3-minute time trial (TTAOP). Sixteen well-trained male cyclists completed the TTSP and TTAOP, on separate days of testing, on a cycling ergometer with power output and respiratory variables measured. Time trials were preceded by 7 × 4-minute submaximal stages of increasing intensity with the linear relationship between power output and metabolic rate used to estimate the contribution from aerobic and anaerobic energy resources. The time course of anaerobic and aerobic contributions to power output was analyzed using statistical parametric mapping. Mean power output was not different between the 2 pacing strategies (TTSP = 417 [43] W, TTAOP = 423 [41] W; P = 0.158). TTAOP resulted in higher peak power output (P < .001), mean ventilation rate (P < .001), mean heart rate (P = .044), peak accumulated anaerobically attributable work (P = .026), post-time-trial blood lactate concentration (P = .035), and rating of perceived exertion (P = .036). Statistical parametric mapping revealed a higher anaerobic contribution to power output during the first ∼30 seconds and a lower contribution between ∼90 and 170 seconds for TTAOP than TTSP. The aerobic contribution to power output was higher between ∼55 and 75 seconds for TTAOP. Although there was no significant difference in performance (ie,mean power output) between the 2 pacing strategies, differences were found in the distribution of anaerobically and aerobically attributable power output. This implies that athletes can pace a 3-minute maximal effort very differently but achieve the same result.