The effect of mental fatigue on critical power during cycling exercise

Mathematical modeling of exercise fatigability in the severe domain: A unifying integrative framework in isokinetic condition

Muscle fatigue is the decay in the ability of muscles to generate force, and results from neural and metabolic perturbations. This article presents an integrative mathematical model that describes the decrease in maximal force capacity (i.e. fatigue) over exercises performed at intensities above the critical force Fc (i.e. severe domain). The model unifies the previous Critical Power Model and All-Out Model and can be applied to any exercise described by a changing force F over time. The assumptions of the model are (i) isokinetic conditions, an intensity domain of Fc Collapse

Key Words

• All-out
• Anaerobic capacities
• Critical power
• Endurance
• Exercise fatigability
• Fatigue
• Maximal force capacity
• Muscular capacities
• Power-time relationship
• Time to exhaustion

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MESH Headings

• Exercise/physiology
• Muscle Fatigue
• Muscles/physiology
• Models, Theoretical
• Muscle, Skeletal/physiology

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Grants Collapse

Affiliation(s) Collapse

Effect of brain endurance training on maximal oxygen uptake, time-to-exhaustion, and inhibitory control in runners

We aimed to analyze the effect of brain endurance training on maximum oxygen consumption (VO2máx ), time-to-exhaustion, and inhibitory control in amateur trained runners. We employed a mixed experimental design, with the group as the between-participant factor and time as the within-participant factor. 45 participants attended 36 training sessions over 12 weeks. The cognitive training group (CT) performed the Stroop word-color task [trials of each type (congruent, incongruent, and neutral) were randomly presented during each training session], the endurance training group (ET) participated in a running training program (intensity was 60%Δ of maximal aerobic velocity and performed on a motor-driven treadmill), and the brain endurance training group (BET) make cognitive and endurance training simultaneously over 12 weeks. The total time of each session (i.e., 20-40 min) was identical in the experimental groups. VO2máx , time-to-exhaustion, and inhibitory control tests were measured before (baseline) and after (post-experiment) the 12-week intervention. A significant effect of interaction (group × time) for VO2máx (p < 0.05) was found. A post-hoc test showed an increase in VO2máx from baseline to post-experiment only for ET (Δ% = 2.98) and BET (Δ% = 3.78) groups (p < 0.05). Also, the analyses showed a significant interaction (group × time) for time-to-exhaustion (p < 0.05), and a post-hoc test revealed an improvement in time-to-exhaustion for ET (Δ% = 8.81) and BET (Δ% = 11.01) (p < 0.05). No group × time interaction was found for accuracy and response time in the inhibitory control task (p > 0.05). The results conclude that BET was not superior to ET for improving VO2máx and time-to-exhaustion. Also, the findings conclude that BET improved inhibitory control similar to CT.

The effect of prolonged use of surgical masks during face-to-face teaching on cognitive and physiological parameters of nursing students: A cross-sectional and descriptive study

AIMS

This study was conducted to examine the effects of using surgical masks on nursing students' cognitive and physiological parameters during full-time face-to-face teaching during the pandemic.

BACKGROUND

It is known that the use of surgical masks has effects on health professionals' physiological parameters.

DESIGN

A descriptive cross-sectional study with a pretest-posttest design was conducted. The study was carried out at a state university.

METHODS

Sixty-one nursing students taking Internal Medicine Nursing course in the fall semester during the COVID-19 pandemic were included in the study. Study data were collected by using a Descriptive Information Form, the Cognitive Fatigue Scale, the One-way Dyspnea Scale and the Cognitive Reaction Time application in a theoretical course that took 310 min on 15 November 2021. Students' physiological parameters were measured by using a thermometer and pulse oximetry.

RESULTS

It was found that students' cognitive fatigue levels (p < 0.001) and body temperature increased (p < 0.001) and that cognitive reaction rates (p = 0.05) and pulse rates decreased (p < 0.001). It was determined that after the lesson, there was a weak positive correlation between nursing students' level of dyspnea and body temperature and their cognitive fatigue levels (p < 0.05).

CONCLUSIONS

It was determined that the use of surgical masks during full-time face-to-face teaching increased students' cognitive fatigue and decreased their cognitive reaction rates. The research will have an impact on redesigning the curriculum for face-to-face teaching. Lecturers should revise their teaching by taking these findings into account.

Interindividual Variability in Mental Fatigue-Related Impairments in Endurance Performance: A Systematic Review and Multiple Meta-regression

BACKGROUND

The negative effect of mental fatigue (MF) on physical performance has recently been questioned. One reason behind this could lie in the interindividual differences in MF-susceptibility and the individual features influencing them. However, the range of individual differences in mental fatigue-susceptibility is not known, and there is no clear consensus on which individual features could be responsible for these differences.

OBJECTIVE

To give an overview of interindividual differences in the effects of MF on whole-body endurance performance, and individual features influencing this effect.

METHODS

The review was registered on the PROSPERO database (CRD42022293242). PubMed, Web of Science, SPORTDiscus and PsycINFO were searched until the 16th of June 2022 for studies detailing the effect of MF on dynamic maximal whole-body endurance performance. Studies needed to include healthy participants, describe at least one individual feature in participant characteristics, and apply at least one manipulation check. The Cochrane crossover risk of bias tool was used to assess risk of bias. The meta-analysis and regression were conducted in R.

RESULTS

Twenty-eight studies were included, with 23 added to the meta-analysis. Overall risk of bias of the included studies was high, with only three presenting an unclear or low rating. The meta-analysis shows the effect of MF on endurance performance was on average slightly negative (g = - 0.32, [95% CI - 0.46; - 0.18], p < 0.001). The multiple meta-regression showed no significant influences of the included features (i.e. age, sex, body mass index and physical fitness level) on MF-susceptibility.

CONCLUSIONS

The present review confirmed the negative impact of MF on endurance performance. However, no individual features influencing MF-susceptibility were identified. This can partially be explained by the multiple methodological limitations such as underreporting of participant characteristics, lack of standardization across studies, and the restricted inclusion of potentially relevant variables. Future research should include a rigorous description of multiple different individual features (e.g., performance level, diet, etc.) to further elucidate MF mechanisms.

A plausible link between the time-on-task effect and the sequential task effect

Mental fatigue can be studied by using either the time-on-task protocol or the sequential task protocol. In the time-on-task protocol, participants perform a long and effortful task and a decrease in performance in this task is generally observed over time. In the sequential task protocol, a first effortful or control task is followed by a second effortful task. The performance in the second task is generally worse after the effortful task than after the control task. The principal aim of the present experiment is to examine the relationship between these two decrements in performance while concomitantly using a sequential task protocol and assessing the performance of the first effortful task as a function of time-on-task. We expect a positive correlation between these two decrements in performance. A total of 83 participants performed a 30-min fatiguing mental task (i.e., a modified Stroop task) or a control task followed by a time-to-exhaustion handgrip task. As expected, this protocol combining the time-on-task and sequential task protocols allowed us to observe (1) a decrease in performance over time during the Stroop task, (2) a worst performance in the handgrip task after the Stroop task by comparison to the control task, (3) a positive correlation between these two effects. The decrease in performance during the Stroop task also correlated with the subjective measures of boredom and fatigue, whereas the detrimental effect observed in the handgrip task did not. Our findings suggest that the two fatigue-related phenomena share a common mechanism but are not completely equivalent.

Neuromuscular and perceptual mechanisms of fatigue accompanying task failure in response to moderate-, heavy-, severe-, and extreme-intensity cycling

A comprehensive characterization of neuromuscular and perceptual mechanisms of fatigue at task failure following exercise across the entire intensity spectrum is lacking. This study evaluated the extent of peripheral and central fatigue, and corresponding perceptual attributes, at task failure following cycling within the moderate-(MOD), heavy-(HVY), severe-(SVR), and extreme-(EXT) intensity domains. After a ramp-incremental test, eleven young males performed four constant-power output trials to the limit of tolerance (T_lim) at four distinct domain-specific workloads. These trials were preceded and followed by 5-s knee-extension maximal voluntary contractions (MVC) and femoral nerve electrical stimuli to quantify peripheral and central fatigue. Additionally, perceptual measures including ratings of global fatigue, legs pain, dyspnea and perceived effort (RPE) were also collected. At T_lim, reductions in MVC were independent of intensity (P>0.05). However, peripheral fatigue was greater following EXT and SVR and progressively, but distinctively, lower following HVY and MOD (P<0.05). Central fatigue was similar after SVR, HVY, and MOD, but absent after EXT (P<0.05). At T_lim, subjective ratings of global fatigue were progressively higher with lower exercise intensities, while ratings of legs pain and dyspnea were progressively higher with higher exercise intensities. On the other hand, RPE was maximal following HVY, SVR, and EXT, but not MOD. The findings demonstrate that at T_lim the extent of peripheral fatigue is highly domain-specific whereas the extent of central fatigue is not. Sensations such as fatigue, pain, and dyspnea may integrate with mechanisms of sense of effort to determine task failure in a manner specific to each intensity domain.

Exploring the Impact of Mental Fatigue and Emotional Suppression on the Performance of High-Intensity Endurance Exercise

This study investigated the extent to which mental fatigue and emotional suppression affected exercise endurance. Twelve participants performed cycling endurance tests at 80% of their peak power up to the point of exhaustion. Two experimental conditions (mental fatigue [MF] and emotion suppression conditions [ES]) and a control condition (CO) were administered. Participants responded to psychological measures throughout the exercise trials. Both MF and ES conditions hindered exercise performance relative to the CO, and there was no statistically significant difference between the negative effects of both MF and ES conditions. Of note, however, higher levels of subjective fatigue were reported in MF, prior to commencing the exercise test. High cognitive loads that induce MF and/or engaging in ES may reduce high intensity endurance exercise performance among young adults, but further research with greater numbers of participants is needed to replicate and extend these findings.

Mental Fatigue Prior to Aerobic Exercise Reduces Exercise Pleasure and Negatively Affects Implicit Attitudes Toward Future Exercise

We investigated the effects of mental fatigue (MF) on affective responses during an aerobic exercise session at moderate intensity. We submitted 12 insufficiently active adults (50% women; M age = 24.9 years, SD = 3.0; M BMI = 24.3 kg/m2; SD = 2.6) to two 30-minute pre-exercise conditions: an MF condition (Stroop Color-Word task) and a control condition (watching a documentary) prior to their performance of 20 minutes of aerobic treadmill exercise at 40–59% of heart rate reserve. The minimum washout interval between conditions was two days. Perceived MF and motivation to perform physical exercise were assessed before and after conditions with a visual analog scale of 100 mm. We assessed participants’ affective and exertion responses with the Feeling Scale, Rating of Perceived Exertion (RPE) and heart rate during every two minutes of physical exercise. Implicit attitudes toward physical exercise were assessed by the Implicit Association Test before the MF and control conditions and after the physical exercise session. The participants in the MF condition reported lower pleasure ( M difference = −1.57, 95% CI = −2.64 to −0.50, d = 0.93, p = .008) and higher exertion (RPE) ( M difference = 1.16, 95% CI = 0.04 to 2.27, d = 0.66, p = .043) compared to those in the control condition. Participants who experienced MF also reported a more negative implicit attitude toward physical exercise than in the control condition ( β = −0.47, 95% CI= −0.73 to −0.21, d = 1.41, p < .001). While these findings should be cross-validated in subsequent research with a larger and more diverse participant sample, there appears to be value in minimizing pre-exercise mental fatigue to avoid negative MF effects on the exercisers’ affective experience.

Does Social Media Use on Smartphones Influence Endurance, Power, and Swimming Performance in High-Level Swimmers?

Objective: This study aimed to investigate the repeated effect of social media on smartphones immediately before training sessions on inhibitory control (Stroop task), endurance (tethered swimming), countermovement jump (CMJ), and swimming performance (50, 100, and 400-m freestyle) in high-level female swimmers. Methods: It is a randomized and experimental investigation with parallel groups. Twenty-two participants underwent the eight weeks of the experiment. The swimmers (eight to twelve sessions per week with 15.9 ± 1.6 hours/week, and training experience of ~ 5.6 years) were randomized in two groups: control (CON, n = 11) and smartphone (SMA, n = 11). Immediately before each training session, the CON group watched videos about Olympic Games for 30-min. The SMA group used social network smartphone apps during 30-min. The inhibitory control, endurance, CMJ, and swimming performance were measured before and after the eight weeks of intervention. Results: No group x time interaction for 50-m freestyle (F_{(4, 18)} = 1.04; p = .33; η² = 0.09) and CMJ performance (F_{(4, 18)} = 0.31; p = .58; η² = 0.03) was found. Both experimental groups improved CMJ (F_{(2, 20)} = 8.71; p = .01; η² = 0.46). Only the CON group improved the 100-m (p = .02), 400-m freestyle (p = .01), and endurance performance (p = .01). The CON group improved the inhibitory control response (p = .01). Conclusion: It is concluded that the repeated effect of social media on smartphones immediately before swimming training sessions might reduce or nullify training gains on swimming and endurance performance.

Impact of a Carbohydrate Mouth Rinse on Corticomotor Excitability after Mental Fatigue in Healthy College-Aged Subjects

Mental Fatigue (MF) has been associated with reduced physical performance but the mechanisms underlying this result are unclear. A reduction in excitability of the corticomotor system is a way mental fatigue could negatively impact physical performance. Carbohydrate (CHO) mouth rinse (MR) has been shown to increase corticomotor excitability. PURPOSE: The purpose of this study was to determine if CHO MR impacts corticomotor excitability after MF. METHODS: Fifteen subjects (nine females, six males; age = 23 ± 1 years; height = 171 ± 2 cm; body mass = 69 ± 3 kg; BMI = 23.8 ± 0.7) completed two sessions under different MR conditions (Placebo (PLAC), 6.4% glucose (CHO)) separated by at least 48 h and applied in a double-blinded randomized fashion. Motor-evoked potential (MEP) of the left first dorsal interosseous (FDI) was determined by transcranial magnetic stimulation (TMS) before and after MF. Perceived MF was recorded before and after the MF task using a 100 mm visual analog scale (VAS). RESULTS: MF was greater following PLAC (+30.4 ± 4.0 mm) than CHO (+19.4 ± 3.9 mm) (p = 0.005). MEP was reduced more following PLAC (−16.6 ± 4.4%) than CHO (−3.7 ± 4.7%) (p < 0.001). CONCLUSIONS: CHO MR was successful at attenuating the reduction in corticomotor excitability after MF. Carbohydrate mouth rinse may be a valuable tool at combating the negative consequences of mental fatigue.

Exercise Intensity and Pacing Pattern During a Cross-Country Olympic Mountain Bike Race

Objective: To examine the power profiles and pacing patterns in relation to critical power (CP) and maximal aerobic power (MAP) output during a cross-country Olympic (XCO) mountain bike race.

Methods: Five male and two female national competitive XCO cyclists completed a UCI Cat. 1 XCO race. The races were 19 km and 23 km and contained five (female) and six (male) laps, respectively. Power output (PO) during the race was measured with the cyclists’ personal power meters. On two laboratory tests using their own bikes and power meters, CP and work capacity above CP (W') were calculated using three time trials of 12, 7, and 3 min, while MAP was established based on a 3-step submaximal test and the maximal oxygen uptake from the 7-min time trial.

Results: Mean PO over the race duration (96 ± 7 min) corresponded to 76 ± 9% of CP and 63 ± 4% of MAP. 40 ± 8% of race time was spent with PO > CP, and the mean duration and magnitude of the bouts >CP was ~8 s and ~120% of CP. From the first to last lap, time >CP and accumulated W' per lap decreased with 9 ± 6% and 45 ± 17%, respectively. For single >CP bouts, mean magnitude and mean W' expended decreased by 25 ± 8% and 38 ± 15% from the first to the last lap, respectively. Number and duration of bouts did not change significantly between laps.

Conclusion: The highly variable pacing pattern in XCO implies the need for rapid changes in metabolic power output, as a result of numerous separate short-lived >CP actions which decrease in magnitude in later laps, but with little lap-to-lap variation in number and duration.

No Effects of Mental Fatigue and Cerebral Stimulation on Physical Performance of Master Swimmers

Background: Mental fatigue is a psychobiological state caused by extended periods of cognitive effort, and evidence suggests that mentally fatigued athletes present impaired physical performance. Different ergogenic aids have been proposed to counteract the deleterious effects of mental fatigue, but whether brain stimulation can counteract mental fatigue is still unknown. This scenario is even more obscure considering the effects of these interventions (mental fatigue induction and brain stimulation) in a very experienced population consisting of master athletes.

Method: Ten master swimmers (30 ± 6 years old and 14 ± 8 years of experience) participated in the study. They underwent four experimental conditions before an 800-m freestyle test: mental fatigue with brain stimulation; mental fatigue without brain stimulation; absence of mental fatigue with brain stimulation; and absence of mental fatigue and no brain stimulation. Mental fatigue was induced by a cognitively demanding Stroop Color Test, whereas stimulation was applied on the temporal cortex. After that, the athletes swan 800 m as fast as possible and provided their ratings of perceived exertion (RPE) every 200 m.

Results: Mental fatigue was effectively induced, as evidenced by a greater fatigue perception and more errors in the last blocks of the cognitive task. Mental fatigue induction did not influence performance (time to complete the swimming trial) and RPE. Similarly, brain stimulation failed to change these two parameters, regardless of mental fatigue induction.

Conclusion: The prolonged physical performance of experienced master athletes is not influenced, under the present conditions, by mental fatigue induction, cerebral stimulation, and their association.

How do elite female team sport athletes experience mental fatigue? Comparison between international competition, training and preparation camps

Mental fatigue has been shown to negatively influence physical, technical and tactical aspects of sporting performance. However, mental fatigue is not routinely monitored or managed in elite sport and it is not clear whether mental fatigue occurs and/or changes across the varied contextual demands experienced by elite athletes in training, preparation and competition. This study explored self-report measures of mental fatigue across eight training camps and six competition periods (two benchmark tournaments and four international test series) with international netballers (n = 22, 25.9 ± 2.7 years) during the 2018-2019 representative period. Mental fatigue was higher during training camps (p < 0.001; 3.20 [3.12, 3.27]) and preparation camps (p < 0.05; 3.27 [3.19, 3.34]) compared to the competition periods (3.49 [3.44, 3.55]). Significant within-group differences were also identified between individual preparation camps and competition subsets. Higher mental fatigue was reported during the preparation camp for international test series 2 comparative to the preparation camp for benchmark tournament 1 (p = 0.047). For individual competitions; greater mental fatigue was found during the international test series 3 competition in comparison to both the benchmark tournament 1 (p <0.001) and international test series 1 (p = 0.020) competition periods. International representative netballers experience differing levels of mental fatigue across training and preparation camps and competition periods. Practitioners should be aware that athletes report instances of elevated mental fatigue across camps, and competition. Mental fatigue is not limited to competition and thus is recommended to be monitored during periods of training and preparation for competition. HighlightsInternational representative netballers experience differing levels of mental fatigue across camp and competition environments.Mental fatigue was higher during training camps and preparation camps compared to the competition periods.Mental fatigue is not limited to competition so is recommended to be monitored during periods of training and preparation for competition.

Critical oxygenation: Can muscle oxygenation inform us about critical power?

The power-duration relationship is well documented for athletic performance and is formulated out mathematically in the critical power (CP) model. The CP model, when applied properly, has great predictive power, e.g. pedaling at a specific power output on an ergometer the model precisely calculates the time over which an athlete can sustain this power. However, CP presents physiological inconsistencies and process-oriented problems. The rapid development of near-infrared spectroscopy (NIRS) to measure muscle oxygenation (SmO₂) dynamics provides a physiological exploration of the CP model on a conceptual and empirical level. Conceptually, the CP model provides two components: first CP is defined as the highest metabolic rate that can be achieved through oxidative means. And second, work capacity above CP named W'. SmO₂ presents a steady-state in oxygen supply and demand and thereby represents CP specifically at a local level of analysis. Empirically, exploratory data quickly illustrates the relationship between performance and SmO₂, as shown during 3-min all-out cycling tests to assess CP. During these tests, performance and SmO₂ essentially mirror each other, and both CP and W' generate solid correlation with what would be deemed their SmO₂ counterparts: first, the steady-state of SmO₂ correlates with CP. And second, the tissue oxygen reserve represented in SmO₂, when calculated as an integral corresponds to W'. While the empirical data presented is preliminary, the proposition of a concurring physiological model to the current CP model is a plausible inference. Here we propose that SmO₂ steady-state representing CP as critical oxygenation or CO. And the tissue oxygen reserve above CO would then be identified as O'. This new CO model could fill in the physiological gap between the highly predictive CP model and at times its inability to track human physiology consistently. For simplicity's sake, this would include acute changes in physiology as a result of changing climate or elevation with travel, which can affect performance. These types of acute fluctuations, but not limited to, would be manageable when applying a CO model in conjunction with the CP model. Further, modeling is needed to investigate the true potential of NIRS to model CP, with a focus on repeatability, recovery, and systemic vs local workloads.

Effects of Mental Fatigue in Total Running Distance and Tactical Behavior During Small-Sided Games: A Systematic Review With a Meta-Analysis in Youth and Young Adult's Soccer Players

Background: Mental fatigue can impact physical demands and tactical behavior in sport-related contexts. Small-sided games (SSGs) are often used to develop a specific sport-related context. However, the effects of mental fatigue on physical demands and tactical behaviors during soccer SSGs have not been aggregated for systematical assessment.

Objective: This systematic review (with a meta-analysis) was conducted to compare the effects of mental fatigue vs. control conditions in terms of the total running distance and tactical behavior of soccer players during SSGs.

Methods: The data sources utilized were PubMed, PsycINFO, Scielo, Scopus, SPORTDiscus, and Web of Science. The study eligibility criteria were established based on PICOS: (i) Population: healthy youth and young adult men soccer players with regular training practice and belonging to teams with regular competitions; (ii) Intervention: exposed to mental fatigue-induced protocols only before SSGs; (iii) Comparator: control conditions (passive or active not promoting mental fatigue) before SSGs; (iv) Outcomes: physical demands (total running distance) and tactical behavior (attacking behavior accuracy, pass decision-making accuracy, and space exploration index); (v) Study design: counterbalanced cross-over design; and (vi) only full-text and original articles written in English.

Results: The database search initially identified 111 titles. From those, six articles were eligible for the systematic review and meta-analysis. Results showed no significant effect of fatigue on total running distance (ES = 0.13; p = 0.307) and tactical behavior (ES = 0.56; p = 0.079).

Conclusions: A non-significant effect of mental fatigue on total running distance and tactical behaviors performed by soccer players during SSGs was found in this systematic review.

Effect of mental fatigue on performance, perceptual and physiological responses in orienteering athletes

BACKGROUND

Mental fatigue seems to impair the athletes' performance; however, in sports with high cognitive demand, such as orienteering, this negative effect could be attenuated during the race. Therefore, this study investigated mental fatigue effect on performance, perceptual, and physiological responses in orienteers.

METHODS

Fifteen male orienteers (30±8 years) participated in the study. Two conditions of cognitive tasks preceded the orienteering performance, performed randomly: 30 minutes of mental exertion (experimental condition [EXP]) by Stroop task, or 30 min without mental exertion (control condition [CON]). Orienteering performance was determined by the time required to perform the Orienteering race. The perceived recovery and motivation were evaluated in each condition, pre-cognitive task, and heart rate during the task. Perceived exertion (RPE) was measured pre- and post-orienteering race. Orienteering performance and perceived performance were measured immediately after the race.

RESULTS

Orienteering performance and remain variables showed no significant differences between conditions (EXP versus CON) (P>0.05). Although a slight increase in performance-time was found in EXP (40.8±11.4 min) versus CON (38.4±13 min) (P=0.4; ES=0.20). RPE increase post-EXP (P<0.05; ES=0.96) but not post-orienteering race (P>0.05).

CONCLUSIONS

Thirty minutes of the cognitive task did not significantly affect the perceptual and physiological responses but demonstrates the addition of 2.4 minutes to orienteering performance. Orienteers may cope with mental effort due to the cognitive demands and physical conditions required in orienteering.

Determinants of last lap speed in paced and maximal 1500-m time trials

PURPOSE

The present study identified the physiological and performance characteristics that are deterministic during a maximal 1500-m time trial and in paced 1500-m time trials, with an all-out last lap.

METHODS

Thirty-two trained middle-distance runners (n = 21 male, VO_2peak: 72.1 ± 3.2; n = 11, female, VO_2peak: 61.2 ± 3.7 mL kg^-1 min^-1) completed a 1500-m time trial in the fastest time possible (1500_FAST) as well as a 1500_MOD and 1500_SLOW trial whereby mean speed was reduced during the 0-1100 m by 5% and 10%, respectively. Anaerobic speed reserve (ASR), running economy (RE), the velocity corresponding with VO_2peak (_VVO_2peak), maximal sprint speed (MSS) and maximal accumulated oxygen deficit (MAOD) were determined during additional testing. Carnosine content was quantified by proton magnetic resonance spectroscopy in the gastrocnemius and expressed as a Z-score to estimate muscle fibre typology.

RESULTS

1500_FAST time was best explained by RE and _VVO_2peak in female runners (adjusted r² = 0.80, P < 0.001), in addition to the 0-1100-m speed relative to _VVO_2peak in male runners (adjusted r² = 0.72, P < 0.001). Runners with a higher gastrocnemius carnosine Z-score (i.e., higher estimated percentage of type II fibres) and greater MAOD, reduced their last lap time to a greater extent in the paced 1500-m trials. Neither ASR nor MSS was associated with last lap time in the paced trials.

CONCLUSION

These findings suggest that _VVO_{2 peak} and RE are key determinants of 1500-m running performance with a sustained pace from the start, while a higher carnosine Z-score and MAOD are more important for last lap speed in tactical 1500-m races.

Mental Fatigue Might Be Not So Bad for Exercise Performance After All: A Systematic Review and Bias-Sensitive Meta-Analysis

There is an ongoing debate in the scientific community regarding whether a state of mental fatigue may have a negative effect upon a range of objective and subjective measures of human performance. This issue has attracted attention from several fields, including sport and exercise sciences. In fact, a considerable body of literature in the sport science field has suggested that performing a long and demanding cognitive task might lead to a state of mental fatigue, impairing subsequent exercise performance, although research in this field has shown contradictory results. Here, we performed a meta-analysis to investigate these inconsistent findings. The analysis yielded small-to-medium effects of mental fatigue on exercise performance, d _z = 0.50, and RPE, d _z = 0.21. However, a three-parameter selection model also revealed evidence of publication or reporting biases, suggesting that the bias-corrected estimates might be substantially lower (0.08 and 0.10, respectively) and non-significant. In sum, current evidence does not provide conclusive support for the claim that mental fatigue has a negative influence on exercise performance.

The Application of Critical Power, the Work Capacity above Critical Power (W'), and its Reconstitution: A Narrative Review of Current Evidence and Implications for Cycling Training Prescription

The two-parameter critical power (CP) model is a robust mathematical interpretation of the power–duration relationship, with CP being the rate associated with the maximal aerobic steady state, and W′ the fixed amount of tolerable work above CP available without any recovery. The aim of this narrative review is to describe the CP concept and the methodologies used to assess it, and to summarize the research applying it to intermittent cycle training techniques. CP and W′ are traditionally assessed using a number of constant work rate cycling tests spread over several days. Alternatively, both the 3-min all-out and ramp all-out protocols provide valid measurements of CP and W′ from a single test, thereby enhancing their suitability to athletes and likely reducing errors associated with the assumptions of the CP model. As CP represents the physiological landmark that is the boundary between heavy and severe intensity domains, it presents several advantages over the de facto arbitrarily defined functional threshold power as the basis for cycle training prescription at intensities up to CP. For intensities above CP, precise prescription is not possible based solely on aerobic measures; however, the addition of the W′ parameter does facilitate the prescription of individualized training intensities and durations within the severe intensity domain. Modelling of W′ reconstitution extends this application, although more research is needed to identify the individual parameters that govern W′ reconstitution rates and their kinetics.

Effect of cycling specialization on effort and physiological responses to uphill and flat cycling at similar intensity

Power output is considered one of the best tools to control external loads in cycling, but the relationship between a target power output and the physiological responses may suffer from the effects of road gradient, which is also affected by cyclist specialization. The objective was to determine the effects of cyclist specialization on effort perception and physiological response (heart rate and lactate concentration) while sustaining efforts at similar power output but riding on two different road gradients. Nineteen male competitive road cyclists performed two randomized trials of 10 min at 0% (velodrome) and 10 min at 6% road gradient (field uphill), at an intensity of 10% ± 3% below the individual's functional threshold power. Cadence was kept between 75 and 80 rpm in both trials and posture remained unchanged during the tests. Heart rate, speed, cadence, power output, blood lactate, and rate of perceived effort were measured for each trial. K-means cluster analyses differentiate uphill (n = 10) and flat specialists (n = 9) according to lactate responses. Flat specialists presented lower heart rate (p < 0.001 and ES = 0.2), perceived exertion (p < 0.01 and ES = 0.7), and blood lactate concentration (p < 0.001 and ES = 0.7) riding on the flat than uphill. Uphill specialists presented lower perceived exertion (p < 0.01 and ES = 0.8) and blood lactate concentration (p < 0.01 and ES = 0.5) riding uphill than on the flat. In conclusion, the combination of cyclist specialization and road gradient affects physiological and effort perception parameters in response to a similar power output demand. These factors deserve attention in training schedules and monitoring performance using power output data.

The effects of predictive trials on critical stroke rate and critical swimming speed

BACKGROUND

Critical swimming speed (CSS) and critical stroke rate (CSR) have important practical applications in evaluating endurance capacity and stroke parameters. The CSS and CSR are determined from the linear regression between two or more performance times with the respective predictive distance or "number of stroke cycles," respectively. It is already known that CSS is dependent on the number and duration of the predictive trials chosen, and performance times ranging from 2 to 12 min have been recommended. However, the effects of predictive trials on the CSR have not been reported. It was hypothesized that CSS and CSR determined by different predictive trials lasting 2 to 12 min would elicit similar values. Therefore, the purpose of the present study was to determine the impact of different combinations of predictive trials lasting 2 to 12 min on both CSR and CSS.

METHODS

Thirteen swimmers performed three fixed-distance (200, 400, and 800 m) performances. All possible combinations of CSR and CSS with two (CSR<inf>200-400</inf>/CSS<inf>200-400</inf>, CSR<inf>200-800</inf>/CSS<inf>200-800</inf>, CSR<inf>400-800</inf>/CSS<inf>400-800</inf>) and three (CSR<inf>200-400-800</inf>/CSS<inf>200-400-800</inf>) trials were determined.

RESULTS

No significant differences were found between CSR and CSS determined with different predictive distance tests. In addition, CSR<inf>200-800</inf> and CSS<inf>200-800</inf> showed the lowest coefficient of variation and highest intraclass correlation coefficients with CSR<inf>200-400-800</inf> and CSS<inf>200-400-800</inf>, respectively.

CONCLUSIONS

This study demonstrated that CSR and CSS were not statistically different when determined with different predictive trials located within the recommended durations of 2-12 min. Nevertheless, CSR<inf>200-800</inf> and CSS<inf>200-800</inf> exhibited the best consistency with CSR<inf>200-400-800</inf> and CSS<inf>200-400-800</inf>, respectively.

Effects of Prior Upper Body Exercise on the 3-min All-Out Cycling Test in Men

INTRODUCTION

Prior upper body exercise reduces the curvature constant (W') of the hyperbolic power-duration relationship without affecting critical power. This study tested the hypothesis that prior upper body exercise reduces the work done over the end-test power (WEP; analog of W') during a 3-min all-out cycling test (3MT) without affecting the end-test power (EP; analog of critical power).

METHODS

Ten endurance-trained men (V˙O2max = 62 ± 5 mL·kg·min) performed a 3MT without (CYC) and with (ARM-CYC) prior severe-intensity, intermittent upper body exercise. EP was calculated as the mean power output over the last 30 s of the 3MT, whereas WEP was calculated as the power-time integral above EP.

RESULTS

At the start of the 3MT, plasma [La] (1.8 ± 0.4 vs 14.1 ± 3.4 mmol·L) and [H] (42.8 ± 3.1 vs 58.6 ± 5.5 nmol·L) were higher, whereas the strong ion difference (41.4 ± 2.2 vs 30.9 ± 4.6 mmol·L) and [HCO3] (27.0 ± 1.9 vs 16.9 ± 3.2 mmol·L) were lower during ARM-CYC than CYC (P < 0.010). EP was 12% lower during the 3MT of ARM-CYC (298 ± 52 W) than CYC (338 ± 60 W; P < 0.001), whereas WEP was not different (CYC: 12.8 ± 3.3 kJ vs ARM-CYC: 13.5 ± 4.1 kJ, P = 0.312). EP in CYC was positively correlated with the peak [H] (r = 0.78, P = 0008) and negatively correlated with the lowest [HCO3] (r = -0.74, P = 0.015).

CONCLUSIONS

These results suggest that EP during a 3MT in endurance-trained men is sensitive to fatigue-related ionic perturbation.

Physical effort exertion and pain: Links with trait-based risk for psychopathology

People with serious mental illness (SMI) are at an increased risk for physical health complications, such as cardiovascular disease and obesity. Low levels of physical activity is a major contributor to these health complications. One factor associated with limited physical activity in the broader sedentary population is pain. While preliminary findings suggest an association between lack of physical activity and pain in SMI, conclusions are still unclear. Thus, the goal of this correlational study was to examine associations between trait-based risk for psychopathology (hypomanic personality, schizotypy, and anhedonic depression) and the experience of pain following a physical endurance/effort task. Healthy participants (N = 43; 18 females) completed self-report measures of trait-based risk for psychopathology. They also reported on the experience of pain before and after the Time To Exhaustion (TTE) test. Findings revealed that risk for psychosis and anhedonic depression were associated with increases in pain following the TTE test, accounting for other key variables, such as age and self-reported physical exercise. Risk for mania was unrelated to changes in pain. These results suggest that the experience of pain in relation to physical endurance/effort may contribute to diminished physical activity among people at risk for SMI.

The application of mental fatigue research to elite team sport performance: New perspectives

OBJECTIVES

Mental fatigue resulting from prolonged periods of demanding cognitive activity, has been found to impair endurance exercise performance and performance in some sport-specific tasks. The application of such research to the elite sporting environment however is limited.

DESIGN & METHODS

This article reviews the literature relevant to mental fatigue and team sporting performance with aim to provide perspectives on the transferability and significance of currently available evidence to the applied elite sporting context.

RESULTS

Inconsistent findings in the limited available literature can be attributed to large variations in the participants involved, the nature of the cognitively demanding tasks used to induce mental fatigue and the tests used to assess performance outcomes. Few studies have used trained athletes in combination with performance tests that accurately represent the physiological and technical demands experienced by athletes in competition. While there is growing interest in the acute influence of mental fatigue on exercise performance, a potential cumulative effect of mental fatigue on performance over, for example, a competitive season is an area yet to be investigated.

CONCLUSIONS

If it is accepted that mental fatigue impairs the performance of some athletes, then improving the ecological validity of research in the area of mental fatigue and sport will significantly advance our understanding of how to better monitor and manage mental fatigue. At the elite level of competition, where outcomes are determined by very small margins of difference, reducing the impact of mental fatigue on performance has potential to be significant.

The influence of knowledge of performance endpoint on pacing strategies, perception of effort, and neural activity during 30-km cycling time trials

It is understood that withholding information during exercise can alter performance during self-paced exercise, though less is known about neural activity during such exercise. The aim of this study was to compare the effects of withholding versus providing distance feedback on perception, muscular activation, and cerebral activity during cycling time trials (TT). Nine well-trained male cyclists randomly completed 2 x 30-km TT, with provision of performance information and distance feedback (known; KTT), and without performance information and remaining distance (unknown; UTT). Prefrontal cortex (PFC) hemoglobin concentration, electroencephalogy (EEG) responses of the parietal lobe (PL) and motor cortex (MC), and surface electromyogram (EMG) of the right thigh were monitored throughout the TTs, in addition to heart rate (HR), rating of perceived exertion (RPE), and power output (PO). Time to completion was shorter for the KTT compared to UTT (51.04 ± 3.26 vs. 49.25 ± 3.57 min, P = 0.01). There were no differences evident for RPE between conditions (P > 0.50). However, during the final 2 km, the KTT presented higher PO (P ≤ 0.05), HR (P = 0.03) and MC, and PL EEG activity (d = 0.51-0.71) in addition to increased tissue hemoglobin index (nTHI) and oxygen extraction (HHb) (d = 0.55-0.65) compared to the UTT. In conclusion, when withholding information pertaining to remaining distance, performance was reduced due to the application of a conservative pacing strategy. In addition, the increase in HHb across the PFC was strongly correlated with PO (r = 0.790; P < 0.001) suggesting knowledge about remaining distance may increase activation across the PFC. Further, it appears that changes within the PFC may play a role in the regulation of cycling performance.

Validity and Reliability of the 3-Minute All-Out Test in National and International Competitive Swimmers

PURPOSE

To assess the concurrent and predictive validity of the 3-minute all-out test (3MT) against conventional methods (CM) of determining critical speed (CS) and curvature constant (D') and to examine the test-retest reliability of the 3MT in highly trained swimmers.

METHODS

Thirteen highly trained swimmers (age 16 [2] y, weight 64.7 [8.5] kg, height 1.76 [0.07] m) completed 4 time trials and two 3MTs over 2 wk. The distance-time (DT) and speed-1/time (1/T) models were used to determine CS and D' from 4 time trials. CS_3MT and [Formula: see text] were determined as the mean speed in the final 30 s of 3MT and as the speed-time integral above CS, respectively.

RESULTS

CS_3MT (1.33 [0.06] m·s^-1) did not differ from CS_CM (1.33 [0.06] m·s^-1, P > .05) and correlated nearly perfectly with CS_CM (r = .95, P < .0001). [Formula: see text] (19.50 [3.52] m) was lower than [Formula: see text] (23.30 [6.24] m, P < .05) and [Formula: see text] (22.15 [5.75] m, P = .09). Correlations between [Formula: see text] and [Formula: see text] were very large (r = .79, P = .002). CS and D' between the two 3MT trials were not different (CS mean change = -0.009 m·s^-1, P = .102; D' mean change = 0.82 m, P = .221). Correlations between the two 3MT trials were nearly perfect and very large for CS (r = .97) and D' (r = .87, P < .05), respectively, with coefficients of variation of 0.9% for CS and 9.1% for D'.

CONCLUSION

The 3MT is a valid protocol for estimation of CS and produces high test-retest reliability for CS and D' in highly trained swimmers.