Respiratory Compensation Threshold Research Articles

Effect of a High-Intensity Circuit Training Program on the Physical Fitness of Wildland Firefighters.

Wildland firefighting implies high physical and psychological demands for the personnel involved. Therefore, good physical fitness can help increase the work efficiency of wildland firefighters (WFFs) and safeguard their health. High-intensity circuit training (HICT) could be a good alternative to improve the physical condition of WFFs since it stands out for its functionality and economy. Therefore, the objective of this study was to analyze the effects of HICT on the WFFs' physical fitness. The study involved 9 WFFs (8 males and 1 female; 29.8 ± 2.8 years; 175.6 ± 6.7 cm) who completed a training program and 9 WFF candidates (8 males and 1 female; 24.7 ± 6.6 yr, 176.5 ± 7.0 cm) as a control group. WFFs performed an 8-week HICT program (two weekly training sessions). The training sessions lasted approximately 45 min and were performed at an intensity >80% of maximal heart rate and RPE values >7.5. At the beginning and the end of the intervention, subjects' physical fitness (i.e., aerobic capacity, cardiorespiratory endurance, muscular resistance and explosive strength) was assessed through different tests. After completing the training program, WFFs had significantly increased (p < 0.05) the speed at which the ventilatory thresholds were determined (12.4 ± 13.9 and 5.7 ± 7.3% for the ventilatory and respiratory compensation thresholds, respectively) and also their abdominal (31.2 ± 17.2%), lumbar (34.1 ± 13.5%) and upper limb (13.3 ± 16.0%) strength. Moreover, improvements (p < 0.05) in the explosive strength of legs (7.1 ± 5.8%) and performance in a specific physical employment test (12.2 ± 6.1%) were observed. In conclusion, the results of this study show that an 8-week high-intensity circuit training program could be an effective and safe method to improve WFFs' physical fitness and performance.

An Examination and Critique of Subjective Methods to Determine Exercise Intensity: The Talk Test, Feeling Scale, and Rating of Perceived Exertion.

Prescribing exercise intensity is crucial in achieving an adequate training stimulus. While numerous objective methods exist and are used in practical settings for exercise intensity prescription, they all require anchor measurements that are derived from a maximal or submaximal graded exercise test or a series of submaximal or supramaximal exercise bouts. Conversely, self-reported subjective methods such as the Talk Test (TT), Feeling Scale (FS) affect rating, and rating of perceived exertion (RPE) do not require exercise testing prior to commencement of the exercise training and therefore appear as more practical tools for exercise intensity prescription. This review is intended to provide basic information on reliability and construct validity of the TT, FS, and RPE measurements to delineate intensity domains. The TT and RPE appear to be valid measures of both the ventilatory threshold and the respiratory compensation threshold. Although not specifically examined, the FS showed tendency to demarcate ventilatory threshold, but its validity to demarcate the respiratory compensation threshold is limited. Equivocal stage of the TT, RPE of 10-11, and FS ratings between fairly good (+ 1) and good (+ 3) are reflective of the ventilatory threshold, while negative stage of the TT, RPE of 13-15, and FS ratings around neutral (0) are reflective of the respiratory compensation threshold. The TT and RPE can effectively be used to elicit homeostatic disturbances consistent with the moderate, heavy, and severe intensity domains, while physiological responses to constant FS ratings show extensive variability around ventilatory threshold to be considered effective in demarcating transition between moderate and heavy intensity domains.

Predictors of CrossFit Open Performance.

The 2018 CrossFit Open (CFO) was the initial stage of an annual competition that consisted of five weekly workouts. Current evidence suggests that a variety of fitness parameters are important for progressing beyond this stage, but little is known about which are the most important. To examine relationships between CFO performance, experience, and physiological fitness, sixteen experienced (>2 years) athletes (30.7 ± 6.9 years, 171 ± 12 cm, 78.0 ± 16.2 kg) volunteered to provide information about their training and competitive history, and then complete a battery of physiological assessments prior to competing in the 2018 CFO. Athletes’ resting energy expenditure, hormone concentrations, body composition, muscle morphology, cardiorespiratory fitness, and isometric strength were assessed on two separate occasions. Spearman correlations demonstrated significant (p < 0.05) relationships between most variables and performance on each workout. Stepwise regression revealed competition experience (R2 = 0.31–0.63), body composition (R2 = 0.55–0.80), vastus lateralis cross-sectional area (R2 = 0.29–0.89), respiratory compensation threshold (R2 = 0.54–0.75), and rate of force development (R2 = 0.30–0.76) to be the most common predictors. Of these, body composition was the most important. These fitness parameters are known targets with established training recommendations. Though preliminary, athletes may use these data to effectively train for CFO competition.

Talk Test As A Measure Of Exercise Intensity In Children

INTRODUCTION: The Talk Test (TT) is a well-accepted measure of exercise intensity and is a useful surrogate of ventilatory (VT) and respiratory compensation (RCT) thresholds in sedentary, fit, athletic, and cardiac populations. Recently, the TT has also been shown to reflect these same markers in children. PURPOSE: The present study was designed 1) to replicate TT results during incremental exercise in children, and 2) to evaluate the ability of the TT to predict when the subjects would be above (-TT) or below (+TT) VT intensity during interval exercise. METHODS: Healthy pre-pubertal children (5m, 5f) were studied using the TT and gas exchange during incremental exercise to determine the match between TT stages and VT. Another group of healthy pre-pubertal children (7m, 6f) were studied both during incremental and stochastic exercise, in order to determine how well TT responses during stochastic exercise predicted whether the children were above or below VT. RESULTS: During incremental exercise, there was good correspondence between the VO2@VT and the VO2@ the last positive (LP) (r=0.79) and the equivocal (EQ) (r=0.75) stages of the TT, which match earlier findings from our laboratory (Giddings et al., 2018; LP TT, r=0.62 & EQ TT, r=0.75). During stochastic exercise, correct matching of predicted vs. observed +TT and predicted vs. observed -TT were present 73% of the time. Discordant results were present 27% of the time. These findings match earlier findings from our laboratory in adults relative to the matching of observed vs. predicted results. CONCLUSION: The TT behaves as a similar surrogate of VT in children, as it does in adults, during both incremental and stochastic exercise.

Time to exhaustion during cycling is not well predicted by critical power calculations.

Three to 5 cycling tests to exhaustion allow prediction of time to exhaustion (TTE) at power output based on calculation of critical power (CP). We aimed to determine the accuracy of CP predictions of TTE at power outputs habitually endured by cyclists. Fourteen endurance-trained male cyclists underwent 4 randomized cycle-ergometer TTE tests at power outputs eliciting (i) mean Wingate anaerobic test (WAnTmean), (ii) maximal oxygen consumption, (iii) respiratory compensation threshold (VT2), and (iv) maximal lactate steady state (MLSS). Tests were conducted in duplicate with coefficient of variation of 5%-9%. Power outputs were 710 ± 63 W for WAnTmean, 366 ± 26 W for maximal oxygen consumption, 302 ± 31 W for VT2 and 247 ± 20 W for MLSS. Corresponding TTE were 00:29 ± 00:06, 03:23 ± 00:45, 11:29 ± 05:07, and 76:05 ± 13:53 min:s, respectively. Power output associated with CP was only 2% lower than MLSS (242 ± 19 vs. 247 ± 20 W; P < 0.001). The CP predictions overestimated TTE at WAnTmean (00:24 ± 00:10 mm:ss) and MLSS (04:41 ± 11:47 min:s), underestimated TTE at VT2 (-04:18 ± 03:20 mm:ss; P < 0.05), and correctly predicted TTE at maximal oxygen consumption. In summary, CP accurately predicts MLSS power output and TTE at maximal oxygen consumption. However, it should not be used to estimate time to exhaustion in trained cyclists at higher or lower power outputs (e.g., sprints and 40-km time trials). Novelty CP calculation enables to predict TTE at any cycling power output. We tested those predictions against measured TTE in a wide range of cycling power outputs. CP appropriately predicted TTE at maximal oxygen consumption intensity but err at higher and lower cycling power outputs.

Quantifying the Training-Intensity Distribution in Middle-Distance Runners: The Influence of Different Methods of Training-Intensity Quantification.

To compare the training-intensity distribution (TID) across an 8-week training period in a group of highly trained middle-distance runners employing 3 different methods of training-intensity quantification. A total of 14 highly trained middle-distance runners performed an incremental treadmill test to exhaustion to determine the heart rate (HR) and running speed corresponding to the ventilatory thresholds (gas-exchange threshold and respiratory-compensation threshold), as well as fixed rating of perceived exertion (RPE) values, which were used to demarcate 3 training-intensity zones. During the following 8weeks, the TID (total and percentage of time spent in each training zone) of all running training sessions (N = 695) was quantified using continuous running speed, HR monitoring, and RPE. Compared with the running-speed-derived TID (zone 1, 79.9% [7.3%]; zone 2, 5.3% [4.9%]; and zone 3, 14.7% [7.3%]), HR-demarcated TID (zone 1, 79.6% [7.2%]; zone 2, 17.0% [6.3%]; and zone 3, 3.4% [2.0%]) resulted in a substantially higher training time in zone 2 (effect size ± 95% confidence interval: -1.64 ± 0.53; P < .001) and lower training time in zone 3 (-1.59 ± 0.51; P < .001). RPE-derived TID (zone 1, 39.6% [8.4%]; zone 2, 31.9% [8.7%]; and zone 3, 28.5% [11.6%]) reduced time in zone 1 compared with both HR (-5.64 ± 1.40; P < .001) and running speed (-5.69 ± 1.9; P < .001), whereas time in RPE training zones 2 and 3 was substantially higher than both HR- and running-speed-derived zones. The results show that the method of training-intensity quantification substantially affects computation of TID.

Examination of gas exchange and blood lactate thresholds in Paralympic athletes during upper-body poling.

ObjectivesThe primary aim was to compare physiological and perceptual outcome parameters identified at common gas exchange and blood lactate (BLa) thresholds in Paralympic athletes while upper-body poling. The secondary aim was to compare the fit of the breakpoint models used to identify thresholds in the gas exchange thresholds data versus continuous linear and curvilinear (no-breakpoint) models.MethodsFifteen elite Para ice hockey players performed seven to eight 5-min stages at increasing workload until exhaustion during upper-body poling. Two regression lines were fitted to the oxygen uptake (VO2)-carbon dioxide (VCO2) and minute ventilation (VE)/VO2 data to determine the ventilatory threshold (VT), and to the VCO2-VE and VE/VCO2 data to determine the respiratory compensation threshold (RCT). The first lactate threshold (LT1) was determined by the first rise in BLa (+0.4mmol·L-1 and +1.0mmol·L-1) and a breakpoint in the log-log transformed VO2-BLa data, and the second lactate threshold (LT2) by a fixed rise in BLa above 4mmol·L-1 and by employing the modified Dmax method. Paired-samples t-tests were used to compare the outcome parameters within and between the different threshold methods. The fit of the two regression lines (breakpoint model) used to identify thresholds in the gas exchange data was compared to that of a single regression line, an exponential and a 3rd order polynomial curve (no-breakpoint models) by Akaike weights.ResultsAll outcome parameters identified with the VT (i.e., breakpoints in the VO2-VCO2 or VE/VO2 data) were significantly higher than the ones identified with a fixed rise in BLa (+0.4 or +1.0mmol·L-1) at the LT1 (e.g. BLa: 5.1±2.2 or 4.9±1.8 vs 1.9±0.6 or 2.3±0.5mmol·L-1,p<0.001), but were not significantly different from the log-log transformed VO2-BLa data (4.3±1.6mmol·L-1,p>0.06). The outcome parameters identified with breakpoints in the VCO2-VE data to determine the RCT (e.g. BLa: 5.5±1.4mmol·L-1) were not different from the ones identified with the modified Dmax method at the LT2 (5.5±1.1mmol·L-1) (all p>0.53), but were higher compared to parameters identified with VE/VCO2 method (4.9±1.5mmol·L-1) and a fixed BLa value of 4mmol·L-1 (all p<0.03). Although we were able to determine the VT and RCT via different gas exchange threshold methods with good fit in all 15 participants (mean R2>0.931), the continuous no-breakpoint models had the highest probability (>68%) of being the best models for the VO2-VCO2 and the VCO2-VE data.ConclusionsIn Paralympic athletes who exercise in the upper-body poling mode, the outcome parameters identified at the VT and the ones identified with fixed methods at the LT1 showed large differences, demonstrating that these cannot be used interchangeably to estimate the aerobic threshold. In addition, the close location of the VT, RCT and LT2 does not allow us to distinguish the aerobic and anaerobic threshold, indicating the presence of only one threshold in athletes with a disability exercising in an upper-body mode. Furthermore, the better fit of continuous no-breakpoint models indicates no presence of clear breakpoints in the gas exchange data for most participants. This makes us question if breakpoints in the gas exchange data really exist in an upper-body exercise mode in athletes with disabilities.

The effects of multi-stage exercise with and without concurrent cognitive performance on cardiorespiratory and cerebral haemodynamic responses.

Studies of cerebral haemodynamics have shown changes with increased exercise intensity, but the patterns have been highly variable and reliable associations with cognitive performance have not been identified. The aim of this study was to examine whether exercise-induced changes in oxygenated haemoglobin (O2Hb) led to changes in concomitant cognitive performance. This study examined cardiorespiratory and cerebral haemodynamics during multi-stage exercise from rest to exhaustion, with (Ex + C) and without (Ex) concurrent cognitive performance (Go/No-go task). The presence of the cognitive task affected both cardiorespiratory and cerebral haemodynamics. The patterns in the cerebral haemodynamics during Ex and Ex + C diverged above the respiratory compensation threshold (RCT), but differences were significant only at 100% [Formula: see text], displaying increased deoxygenated haemoglobin (HHb), decreased difference between oxygenated and deoxygenated haemoglobin (HbDiff), and decreased cerebral oxygenation (COx) during Ex + C. More complex haemodynamic trends against intensity during Ex + C suggested that the presence of a cognitive task increases cerebral metabolic demand at high exercise intensities. The levels of O2Hb, HHb, HbDiff and total haemoglobin increased most steeply at intensities around the RCT during both Ex and Ex + C, but these changes were not accompanied by improved cognitive performance. The primary hypothesis, that cognitive performance would match changes in O2Hb, was not supported. Small variations in reaction time and response accuracy across exercise intensities were not significant, suggesting that cognitive performance is unaffected by intense short-duration exercise. Our results add further evidence that exercise-induced changes in cerebral haemodynamics do not affect cognitive performance.

Baseline Ventilatory Thresholds Determine Cardiorespiratory Adaptations to High-Intensity Interval Training in Obese Participants

PURPOSE: To study if cardiorespiratory fitness (CRF) evolution after high intensity interval training (HIIT) depends on training intensity relative to ventilatory thresholds (VTs). METHODS: A sample (n=134) of sedentary participants with obesity (54±9 years, BMI 31.6±5.6 kg·m-2, 42% female) trained for 16 weeks, 3 days·week-1 alternating bouts of 70-90% of peak heart rate (HR). CRF was evaluated before and after training using a graded cycle-ergometer exercise tests (GXT) until exhaustion. Starting at rest, oxygen consumption (VO2), power output (PO), and HR, were determined at ventilatory threshold (VT1), respiratory compensation threshold (VT2) and at maximal values (PEAK). Participants were separated in two groups according to the relationship between the training intensity (target-HR based) and the VTs location. One group (BelowVTs) was composed for those who trained below their VTs (n=74), whereas the other group (AboveVTs) for those who trained above their VTs (n=60). RESULTS: Before intervention, age and body composition were similar in both groups. While at baseline, VO2 at PEAK was higher in AboveVTs (P=0.005), at VT1, and VT2, was similar in both groups. After training, both groups improved their VO2PEAK by 11-12% (P<0.001) without differences between groups (P=0.880). However, in BelowVTs group, 54% of the VO2, improvement occurred below VT1, 12% between VTs and 33% above VT2, whereas for AboveVTs, 96% of the VO2 improvement occurred below VT1, 0% between VTs and 4% above VT2. CONCLUSIONS: Target-HR based HIIT improves VO2PEAK in middle-aged individuals with obesity independently of the VTs location. However, the extent of the widening of exercise workloads tolerated after the onset of metabolic acidosis (i.e., improvements above VT2) and exercise workloads supplied solely with oxidative metabolism (i.e., improvements at VT1) depends if the workload chosen for training fall above or below the workload at both VTs.

Effect of 8 weeks of concurrent plyometric and running training on spatiotemporal and physiological variables of novice runners

Concurrent plyometric and running training has the potential to improve running economy (RE) and performance through increasing muscle strength and power, but the possible effect on spatiotemporal parameters of running has not been studied yet. The aim of this study was to compare the effect of 8 weeks of concurrent plyometric and running training on spatiotemporal parameters and physiological variables of novice runners. Twenty-five male participants were randomly assigned into two training groups; running group (RG) (n = 11) and running + plyometric group (RPG) (n = 14). Both groups performed 8 weeks of running training programme, and only the RPG performed a concurrent plyometric training programme (two sessions per week). Anthropometric, physiological (VO2max, heart rate and RE) and spatiotemporal variables (contact and flight times, step rate and length) were registered before and after the intervention. In comparison to RG, the RPG reduced step rate and increased flight times at the same running speeds (P < .05) while contact times remained constant. Significant increases in pre- and post-training (P < .05) were found in RPG for squat jump and 5 bound test, while RG remained unchanged. Peak speed, ventilatory threshold (VT) speed and respiratory compensation threshold (RCT) speed increased (P < .05) for both groups, although peak speed and VO2max increased more in the RPG than in the RG. In conclusion, concurrent plyometric and running training entails a reduction in step rate, as well as increases in VT speed, RCT speed, peak speed and VO2max. Athletes could benefit from plyometric training in order to improve their strength, which would contribute to them attaining higher running speeds.

Differences in Spatiotemporal Parameters Between Trained Runners and Untrained Participants.

Gómez-Molina, J, Ogueta-Alday, A, Stickley, C, Tobalina, JC, Cabrejas-Ugartondo, J, and García-López, J. Differences in spatiotemporal parameters between trained runners and untrained participants. J Strength Cond Res 31(8): 2169-2175, 2017-The aim of this study was to compare the spatiotemporal parameters of trained runners and untrained participants with the same foot strike pattern (rearfoot) during running at controlled speeds. Twenty-one participants were classified in 2 groups according to their training experience: Trained (n = 10, amateur runners with long distance training experience) and Untrained (n = 11, healthy untrained participants). Anthropometric variables were recorded, and the participants performed both a submaximal (between 9 and 15 km·h) and a graded exercise running test (from 6 km·h until exhaustion) on a treadmill. Physiological (V[Combining Dot Above]O2max, heart rate, running economy [RE], peak speed …) and biomechanical variables (contact and flight times, step rate, and length) were simultaneously registered. Trained runners showed higher step rate and shorter step length than the Untrained group at the same running speeds (between 4 and 7%, p ≤ 0.05) and at the same physiological intensities (between 7 and 11%, p ≤ 0.05). However, there were no differences in contact and flight times between groups. Significant differences (p ≤ 0.05) and large effect sizes (Cohen's d) between groups were found for body mass, sum of 6 skinfolds, V[Combining Dot Above]O2max, peak speed, and ventilatory threshold and respiratory compensation threshold speeds. The Trained group also showed a ∼7% better RE (ml·kg·km) than the Untrained group. In conclusion, adopting higher step rate and shorter step length may be an adaptive mechanism of the Trained group to reduce injury risk and possibly improve RE. However, contact and flight times were consistent regardless of training level.

Effects of speech passage length on accuracy of predicting metabolic thresholds using the talk test

The Talk Test (TT) is a simple technique for prescribing exercise training intensity, based on the ability to ‘speak comfortably’ after reciting a standard speech provoking stimulus. This study compares the length of the speech provoking stimulus on power output (PO) at standard TT speech comfort markers: last positive (LP), equivocal (EQ), negative (NEG), in relation to objective markers of exercise intensity, the ventilatory (VT) and respiratory compensation (RCT) thresholds. Eighteen healthy subjects performed incremental (25W/2 min) exercise with concomitant gas exchange to measure VT and RCT. They also performed (random order) incremental exercise without gas exchange while repeating standard speech provoking stimuli of 31, 62 and 93 words to allow identification of the LP, EQ and NEG stages of the TT. The mean (±SD) PO at LP (139±38, 117±39 and 103±38 W), EQ (164±38, 142±38 and 128±33 W) and NEG (196±42, 189±43, and 174±39 W) stages of the TT were analyzed for 31, 62 and 93 word passages, in relation to the PO at VT (128±43 W) and RCT (175±39W). PO at EQ and PO at NEG stages of the TT with the 93 word speech provoking stimulus were not significantly different than the PO at VT and PO at RCT, respectively. The mean error for predicting PO at VT approximated zero with the longer (93 word) speech passage duration for EQ (0.1±37 W) and for predicting the PO at RCT for NEG (0.1±29 W). The results suggest that a longer duration speech provoking passage optimizes accuracy of the TT estimation of VT and RCT

The physiological mechanism behind the talk test

The Talk Test (TT) is a very simple marker of exercise intensity, which has been shown to be a useful surrogate of the ventilatory (VT) and respiratory compensation (RCT) thresholds. The purpose of this study was to evaluate a potential mechanism behind the TT. Healthy, college-aged subjects (n=20) performed a maximal and two sub-maximal cycle ergometer tests. The two submaximal tests were performed: with the Talk Test (EXP) and without speaking (the control trial – CON). Oxygen uptake (VO2), CO2 output (VCO2), minute ventilation (VE), breathing frequency (BF), end-tidal CO2 pressure (PETCO2) and TT times were recorded. VO2, VCO2 and VE were reduced during the TT and increased immediately after it. BF was reduced during the TT. PETCO2 values (a surrogate of PaCO2) were highest during the TT and lowest before the TT. The time to complete the TT increased across progressive stages. This study supports the hypothesis that talking causes CO2 retention, which may cause ventilatory drive to increase. Since the ventilatory drive is already high above the VT, the apparent CO2 retention associated with speech may cause talking to become uncomfortable

Temporal Robustness of the Session Rating of Perceived Exertion.

The session rating of perceived exertion (sRPE) has gained popularity as a "user friendly" method for evaluating internal training load. sRPE has historically been obtained 30 min after exercise. This study evaluated the effect of postexercise measurement time on sRPE after steady-state and interval cycle exercise. Well-trained subjects (N = 15) (maximal oxygen consumption = 51 ± 4 and 36 ± 4 mL/kg [cycle ergometer] for men and women, respectively) completed counterbalanced 30-minute steady-state and interval training bouts. The steady-state ride was at 90% of ventilatory threshold. The work-to-rest ratio of the interval rides was 1:1, and the interval segment durations were 1, 2, and 3 min. The high-intensity component of each interval bout was 75% peak power output, which was accepted as a surrogate of the respiratory compensation threshold, critical power, or maximal lactate steady state. Heart rate, blood lactate, and rating of perceived exertion (RPE) were measured. The sRPE (category ratio scale) was measured at 5, 10, 15, 20, 25, 30, and 60 min and 24 h after each ride using a visual analog scale (VAS) to prevent bias associated with specific RPE verbal anchors. sRPE at 30 min postexercise followed a similar trend: steady state = 3.7, 1 min = 3.9, 2 min = 4.7, 3 min = 6.2. No significant differences (P > .05) in sRPE were found based on postexercise sampling times, from 5 min to 24 h postexercise. Postexercise time does not appear to have a significant effect on sRPE after either steady-state or interval exercise. Thus, sRPE appears to be temporally robust and is not necessarily limited to the 30-min-postexercise window historically used with this technique, although the presence or absence of a cooldown period after the exercise bout may be important.

Do physiological measures predict selected CrossFit(®) benchmark performance?

PurposeCrossFit® is a new but extremely popular method of exercise training and competition that involves constantly varied functional movements performed at high intensity. Despite the popularity of this training method, the physiological determinants of CrossFit performance have not yet been reported. The purpose of this study was to determine whether physiological and/or muscle strength measures could predict performance on three common CrossFit “Workouts of the Day” (WODs).Materials and methodsFourteen CrossFit Open or Regional athletes completed, on separate days, the WODs “Grace” (30 clean and jerks for time), “Fran” (three rounds of thrusters and pull-ups for 21, 15, and nine repetitions), and “Cindy” (20 minutes of rounds of five pull-ups, ten push-ups, and 15 bodyweight squats), as well as the “CrossFit Total” (1 repetition max [1RM] back squat, overhead press, and deadlift), maximal oxygen consumption (VO2max), and Wingate anaerobic power/capacity testing.ResultsPerformance of Grace and Fran was related to whole-body strength (CrossFit Total) (r=−0.88 and −0.65, respectively) and anaerobic threshold (r=−0.61 and −0.53, respectively); however, whole-body strength was the only variable to survive the prediction regression for both of these WODs (R2=0.77 and 0.42, respectively). There were no significant associations or predictors for Cindy.ConclusionCrossFit benchmark WOD performance cannot be predicted by VO2max, Wingate power/capacity, or either respiratory compensation or anaerobic thresholds. Of the data measured, only whole-body strength can partially explain performance on Grace and Fran, although anaerobic threshold also exhibited association with performance. Along with their typical training, CrossFit athletes should likely ensure an adequate level of strength and aerobic endurance to optimize performance on at least some benchmark WODs.

Effect of Speech Passage Duration on Talk Test Response

The Talk Test (TT) is a simple technique for prescribing exercise training intensity, based on the ability to ‘speak comfortably’ after reciting a standard speech provoking stimulus. PURPOSE: This study compares the duration of the speech provoking stimulus on the PO at standard TT speech comfort markers (Last Positive (LP), Equivocal (EQ), Negative (NEG). METHODS: Healthy subjects performed incremental (25W/2 min) exercise with gas exchange to measure ventilatory (VT) and respiratory compensation (RCT) thresholds. They also performed incremental exercise (random order) while repeating a standard speech provoking stimulus (31 words) 1x, 2x or 3x to allow identification of LP, EQ & NEG points in the TT. The PO at LP, EQ & NEG, in relation to the PO at VT & RCT were compared. RESULTS: The relationship between [email protected] vs LP1,2,3 (r=0.73, 0.65, 0.56) and EQ1,2,3 (r=0.74, 0.65, 0.56) and RCT vs NEG1,2,3 (r=0.78, 0.80.0.71) were reasonably strong. The mean error for predicting [email protected] was smaller with longer speech passage durations for LP1,2,3 (+11±29.6, -11.±34.2, -25+34.7 W), for EQ1,2,3 (+36±29.7, +14.±34.2, +0.1±36.65 W), and for NEG1,2,3 vs RCT (+18±24.8, +11±23.2, −0.11±28.9 W). CONCLUSION: The results suggest that longer speech duration passages (10 vs 20 vs 29s) give more a more accurate prediction of VT/RCT based on TT EQ and NEG responses.

Measuring the Talk Test as a Continuous Rather than Categorical Variable

PURPOSE: The Talk Test (TT) is a useful surrogate of ventilatory (VT) and respiratory compensation (RCT) thresholds in exercise prescription. It is inherently a categorical variable, however the factors driving speech difficulty are likely more continuous than categorical. This study examines the perception of speech difficulty, using a visual analog scale, versus the traditional categorical variables. METHODS: Physically active volunteers (n=20) performed three incremental (25W + 25W/2 min) cycle tests in a counterbalanced order: a) with gas exchange to measure VT & RCT, b) with normal TT categories (Positive, Equivocal, Negative) at the end of each stage, and c) by marking a visual analog scale (VAS) at the end of each stage. RESULTS: The VAS rating of speech difficulty @ Max=9.3 + 1.1, @ RCT=6.6 + 2.3, and at VT=4.3 + 2.3 were similar to the VAS rating at the LP TT=3.1 + 0.6, EQ=4.3+1.1 and NEG=5.6+1.4, were very similar to the RPE ratings. The overall curve of VAS ratings changed smoothly across TT categories (figure). CONCLUSIONS: Although the TT is clearly a categorical ranking method, it appears to represent boundaries in a smoothly increasing sense of speech difficulty that is closely associated with VT & RCT.

An evaluation of upper-body muscle activation during coupled and uncoupled instability resistance training.

Recently, there has been a growth in the popularity of resistance exercises performed on unstable surfaces. However, the relationship between unstable surface training and load coupling on muscle activation is unclear. The purpose of this study was to evaluate changes in muscle activation during a barbell (BB) (coupled) and dumbbell (DB) (uncoupled) chest press exercise performed on an unstable surface. The 3 specific chest press conditions included 50% 1 repetition maximum (RM) with BB (50% BB), 50% 1RM with DBs (50% DB), and 25% 1RM with DBs (25% DB). Ten male subjects participated in the study (age, 23.9 ± 2.6 years; body weight, 82.8 ± 10.2 kg). During testing, mean electromyographic activity was assessed for pectoralis major (PM), triceps brachii, anterior deltoid (AD), and rectus abdominis (RA) and was presented as a percent change across the lifting conditions. It was observed that muscle activation increased by 15% in both the PM and RA from the 50% BB condition to the 50% DB condition. Also, the greatest percent difference in muscle activation between the 50 and 25% DB conditions occurred for PM and AD (+54% during 50% DB). These results suggest that demands on the core musculature to provide stability are increased with the use of DBs (uncoupled) as opposed to a BB (coupled). Where instability training provides a sufficient hypertrophy stimulus in prime mover muscle groups, there may be the added benefit of core stability training. Specifically, this type of training may benefit both untrained persons and those engaged in active rehabilitation.

Maximal lactate steady state in Judo

the purpose of this study was to verify the validity of respiratory compensation threshold (RCT) measured during a new single judo specific incremental test (JSIT) for aerobic demand evaluation. to test the validity of the new test, the JSIT was compared with Maximal Lactate Steady State (MLSS), which is the gold standard procedure for aerobic demand measuring. Eight well-trained male competitive judo players (24.3 ± 7.9 years; height of 169.3 ± 6.7cm; fat mass of 12.7 ± 3.9%) performed a maximal incremental specific test for judo to assess the RCT and performed on 30-minute MLSS test, where both tests were performed mimicking the UchiKomi drills. the intensity at RCT measured on JSIT was not significantly different compared to MLSS (p=0.40). In addition, it was observed high and significant correlation between MLSS and RCT (r=0.90, p=0.002), as well as a high agreement. RCT measured during JSIT is a valid procedure to measure the aerobic demand, respecting the ecological validity of Judo.

The Effect of Adding CO2 to Hypoxic Inspired Gas on Cerebral Blood Flow Velocity and Breathing during Incremental Exercise

Hypoxia increases the ventilatory response to exercise, which leads to hyperventilation-induced hypocapnia and subsequent reduction in cerebral blood flow (CBF). We studied the effects of adding CO2 to a hypoxic inspired gas on CBF during heavy exercise in an altitude naïve population. We hypothesized that augmented inspired CO2 and hypoxia would exert synergistic effects on increasing CBF during exercise, which would improve exercise capacity compared to hypocapnic hypoxia. We also examined the responsiveness of CO2 and O2 chemoreception on the regulation ventilation (E) during incremental exercise. We measured middle cerebral artery velocity (MCAv; index of CBF), E, end-tidal PCO2, respiratory compensation threshold (RC) and ventilatory response to exercise (E slope) in ten healthy men during incremental cycling to exhaustion in normoxia and hypoxia (FIO2 = 0.10) with and without augmenting the fraction of inspired CO2 (FICO2). During exercise in normoxia, augmenting FICO2 elevated MCAv throughout exercise and lowered both RC onset andE slope below RC (P<0.05). In hypoxia, MCAv and E slope below RC during exercise were elevated, while the onset of RC occurred at lower exercise intensity (P<0.05). Augmenting FICO2 in hypoxia increased E at RC (P<0.05) but no difference was observed in RC onset, MCAv, or E slope below RC (P>0.05). The E slope above RC was unchanged with either hypoxia or augmented FICO2 (P>0.05). We found augmenting FICO2 increased CBF during sub-maximal exercise in normoxia, but not in hypoxia, indicating that the ‘normal’ cerebrovascular response to hypercapnia is blunted during exercise in hypoxia, possibly due to an exhaustion of cerebral vasodilatory reserve. This finding may explain the lack of improvement of exercise capacity in hypoxia with augmented CO2. Our data further indicate that, during exercise below RC, chemoreception is responsive, while above RC the ventilatory response to CO2 is blunted.