Given the important role of the brain in regulating endurance performance, this comparative study sought to determine whether professional road cyclists have superior inhibitory control and ...resistance to mental fatigue compared to recreational road cyclists.
After preliminary testing and familiarization, eleven professional and nine recreational road cyclists visited the lab on two occasions to complete a modified incongruent colour-word Stroop task (a cognitive task requiring inhibitory control) for 30 min (mental exertion condition), or an easy cognitive task for 10 min (control condition) in a randomized, counterbalanced cross-over order. After each cognitive task, participants completed a 20-min time trial on a cycle ergometer. During the time trial, heart rate, blood lactate concentration, and rating of perceived exertion (RPE) were recorded.
The professional cyclists completed more correct responses during the Stroop task than the recreational cyclists (705±68 vs 576±74, p = 0.001). During the time trial, the recreational cyclists produced a lower mean power output in the mental exertion condition compared to the control condition (216±33 vs 226±25 W, p = 0.014). There was no difference between conditions for the professional cyclists (323±42 vs 326±35 W, p = 0.502). Heart rate, blood lactate concentration, and RPE were not significantly different between the mental exertion and control conditions in both groups.
The professional cyclists exhibited superior performance during the Stroop task which is indicative of stronger inhibitory control than the recreational cyclists. The professional cyclists also displayed a greater resistance to the negative effects of mental fatigue as demonstrated by no significant differences in perception of effort and time trial performance between the mental exertion and control conditions. These findings suggest that inhibitory control and resistance to mental fatigue may contribute to successful road cycling performance. These psychobiological characteristics may be either genetic and/or developed through the training and lifestyle of professional road cyclists.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Critics of this simple approach claim that to detect lameness one must specifically and simultaneously observe for many other signs, including movement of the limbs during the swing phase of the ...stride, cadence of footfall, orientation and placement of the limbs during weight bearing, the apparent ease, comfort, or ability to move in certain gaits, or to transition from one gait to another and other, even more difficult-to-define, signs like head orientation and facial expression.25 I have also observed for most of these signs. In a study tracking the eye movement of veterinary students evaluating videos of lame horses, it was shown that experienced students who concentrated on head and pelvic movement scored significantly better at picking the correct lame limb than inexperienced students who looked at head, pelvis and limb movement and who named a greater number of visual lameness features that they thought were important to track.26 When veterinary trainees are told specifically what to observe, in language clear enough to propose a way to measure it, they can learn to be proficient. Assessment of mild hindlimb lameness during over ground locomotion using linear discriminant analysis of inertial sensor data. Disease-specific changes in equine ground reaction force data documented by use of principal component analysis.
This study has investigated the immediate effect of induced hindlimb length difference on hindlimb lameness measured as differences in minimum (Pmin) and maximum (Pmax) pelvic heights in 16 horses ...trotting in a straight line and lungeing on both hard and soft surfaces with body-mounted inertial sensors. Hindlimb length differences were induced by applying an Easyboot Glue-on shoe to one hindlimb. Changes in Pmin and Pmax with induced hindlimb length difference were assessed with a two-way repeated-measures ANOVA with trial (straight, lunge with inside limb elevation, lunge with outside limb elevation) and surface (hard, soft) as within-subject factors. Change in Pmin, indicating an impact-type lameness, in the hind limb with the elevation, was significant in both the straight line and while lunging on both hard and soft surfaces. Change in Pmax, indicating pushoff-type lameness, in the opposite, non-elevated hind limb, was significant when trotting in a straight line but not while lunging.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Purpose
Mental fatigue can negatively impact on submaximal endurance exercise and has been attributed to changes in perceived exertion rather than changes in physiological variables. The impact of ...mental fatigue on maximal anaerobic performance is, however, unclear. Therefore, the aim of the present study was to induce a state of mental fatigue to examine the effects on performance, physiological and perceptual variables from subsequent tests of power, strength and anaerobic capacity.
Methods
Twelve participants took part in the single-blind, randomised, crossover design study. Mental fatigue was induced by 90 min of the computer-based Continuous Performance Task AX version. Control treatment consisted of 90 min of watching emotionally neutral documentaries. Participants consequently completed countermovement jump, isometric leg extension and a 3-min all-out cycling tests.
Results
Results of repeated measures analysis of variance and paired
t
tests revealed no difference in any performance or physiological variable. Rating of perceived exertion tended to be greater when mentally fatigued (mental fatigue = 19 ± 1 vs control = 18 ± 1,
p
= 0.096,
η
p
2
= .232) and intrinsic motivation reduced (mental fatigue = 11 ± 4 vs control = 13 ± 6,
p
= 0.063,
d
= 0.597) in the mental fatigue condition.
Conclusions
Near identical responses in performance and physiological parameters between mental fatigue and control conditions suggest that peripheral mechanisms primarily regulate maximal anaerobic exercise. Whereas mental fatigue can negatively impact submaximal endurance exercise, it appears that explosive power, voluntary maximal strength and anaerobic work capacity are unaffected.
OBJECTIVE To investigate associations between inertial sensor and stationary force plate measurements of hind limb lameness in horses. ANIMALS 21 adult horses with no lameness or with mild hind limb ...lameness. PROCEDURES Horses were instrumented with inertial sensors and evaluated for lameness with a stationary force plate while trotting in a straight line. Inertial sensor–derived measurements of maximum and minimum pelvic height differences between right and left halves of the stride were compared with vertical and horizontal ground reaction forces (GRFs). Stepwise linear regression was performed to investigate the strength of association between inertial sensor measurements of hind limb lameness and amplitude, impulse, and time indices of important events in the vertical and horizontal GRF patterns. RESULTS Difference in minimum pelvic position was moderately (Ra2 = 0.60) associated with the difference in peak vertical GRF but had little association with any horizontal GRF measurements. Difference in maximum pelvic position was strongly (Ra2 = 0.77) associated with a transfer of vertical to horizontal ground reaction impulse in the second half of the stance but was not associated with difference in peak vertical GRF. CONCLUSIONS AND CLINICAL RELEVANCE Inertial sensor–derived measurements of asymmetric pelvic fall (difference in minimum pelvic position) indicated a decrease in vertical GRF, but similar measurements of asymmetric pelvis rise (difference in maximum pelvic position) indicated a transfer of vertical to horizontal force impulse in the second half of the stance. Evaluation of both pelvic rise and fall may be important when assessing hind limb lameness in horses.
The ergogenic effects of analgesic substances suggest that pain perception is an important regulator of work-rate during fatiguing exercise. Recent research has shown that endogenous inhibitory ...responses, which act to attenuate nociceptive input and reduce perceived pain, can be increased following transcranial direct current stimulation of the hand motor cortex. Using high-definition transcranial direct current stimulation (HD-tDCS; 2 mA, 20 min), the current study aimed to examine the effects of elevated pain inhibitory capacity on endurance exercise performance. It was hypothesised that HD-tDCS would enhance the efficiency of the endogenous pain inhibitory response and improve endurance exercise performance.
Twelve healthy males between 18 and 40 years of age (
= 24.42 ± 3.85) were recruited for participation. Endogenous pain inhibitory capacity and exercise performance were assessed before and after both active and sham (placebo) stimulation. The conditioned pain modulation protocol was used for the measurement of pain inhibition. Exercise performance assessment consisted of both maximal voluntary contraction (MVC) and submaximal muscular endurance performance trials using isometric contractions of the non-dominant leg extensors.
Active HD-tDCS (pre-tDCS, -.32 ± 1.33 kg; post-tDCS, -1.23 ± 1.21 kg) significantly increased pain inhibitory responses relative to the effects of sham HD-tDCS (pre-tDCS, -.91 ± .92 kg; post-tDCS, -.26 ± .92 kg;
= .046). Irrespective of condition, peak MVC force and muscular endurance was reduced from pre- to post-stimulation. HD-tDCS did not significantly influence this reduction in maximal force (active: pre-tDCS, 264.89 ± 66.87 Nm; post-tDCS, 236.33 ± 66.51 Nm; sham: pre-tDCS, 249.25 ± 88.56 Nm; post-tDCS, 239.63 ± 67.53 Nm) or muscular endurance (active: pre-tDCS, 104.65 ± 42.36 s; post-tDCS, 93.07 ± 33.73 s; sham: pre-tDCS, 123.42 ± 72.48 s; post-tDCS, 100.27 ± 44.25 s).
Despite increasing pain inhibitory capacity relative to sham stimulation, active HD-tDCS did not significantly elevate maximal force production or muscular endurance. These findings question the role of endogenous pain inhibitory networks in the regulation of exercise performance.
To compare results for initial body-mounted inertial sensor (BMIS) measurement of lameness in equids trotting in a straight line with definitive findings after full lameness evaluation.
1,224 equids.
...Lameness measured with BMIS equipment while trotting in a straight line was classified into categories of none, forelimb only, hind limb only, and 8 patterns of combined forelimb and hind limb lameness (CFHL). Definitive findings after full lameness evaluation were established in most horses and classified into types (no lameness, forelimb- or hind limb-only lameness, CFHL, or lameness not localized to the limbs). Observed proportions of lameness type in equids with definitive findings for each initial BMIS-assessed category were compared with hypothetical expected proportions through χ
goodness-of-fit analysis.
The most common initial BMIS-assessed lameness category was CFHL (693/1,224 56.6%), but this was the least common definitive finding (94/ 862 10.9%). The observed frequency of no lameness after full lameness evaluation was greater than expected only when initial BMIS measurements indicated no lameness. The observed frequency of forelimb-only lameness was greater than expected when initially measured as forelimb-only lameness and for CFHL categories consistent with the diagonal movement principle of compensatory lameness. Observed frequency of hind limb-only lameness was greater than expected when initially measured as hind limb-only lameness and for CFHL categories consistent with the sagittal movement principle of compensatory lameness. Equids initially assessed as having no lameness had the highest (103/112 92%) and those assessed as CFHL pattern 7 (forelimb with contralateral hind limb impact-only lameness) had the lowest (36/66 55%) rates of definitive findings.
In equids, results of initial straight-line trotting evaluations with a BMIS system did not necessarily match definitive findings but may be useful in planning the remaining lameness evaluation.
The aim of this study was to investigate whether individuals who engage in more frequent self-regulation are less susceptible to mental fatigue. Occupational cognitive demand and participation in ...sports or exercise were quantified as activities requiring self-regulation. Cardiorespiratory fitness was also assessed. On separate occasions, participants either completed 90 min of an incongruent Stroop task (mental exertion condition) or watched a 90-min documentary (control condition). Participants then completed a cycling time-to-exhaustion (physical endurance) test. There was no difference in the mean time to exhaustion between conditions, although individual responses varied. Occupational cognitive demand, participation in sports or exercise, and cardiorespiratory fitness predicted the change in endurance performance (p = .026, adjusted R2 = .279). Only cognitive demand added significantly to the prediction (p = .024). Participants who reported higher levels of occupational cognitive demand better maintained endurance performance following mental exertion.
Soluble epoxide hydrolase (sEH) inhibitors are novel anti-inflammatory and analgesic agents that could improve pain management in horses. The objective of the present study was to evaluate the ...anti-nociceptive effect of a single-dose intravenous administration of the sEH inhibitor trans-4-{4-3-(4-trifluro-methoxy-phenyl)-ureido-cyclohexyloxy}-benzoic acid (t-TUCB) using an adjustable heart bar shoe (a-HBS) model of lameness. We hypothesized that t-TUCB would improve objective and subjective lameness measures compared to the control.
Reversible lameness was induced in 8 horses for 24 h using an a-HBS in a randomized, crossover design. A vehicle-control placebo (DMSO) or t-TUCB (1 mg/kg) was intravenously administered at time 0 following a baseline induced lameness evaluation. Blood was collected and lameness was objectively measured with an inertial sensor system at 0-, 1-, 3-, 6-, 12-, and 24-h time points. Front-facing videos were obtained at each time point for subjective evaluation by three blinded evaluators using a visual analog scale (VAS).
Treatment with t-TUCB significantly decreased (i.e. improved) lameness compared to placebo at 1-h and compared to baseline at 1-, 3-, and 6-h following administration. Lameness significantly increased (i.e. worsened) from baseline in placebo-treated horses 12 h after administration. All horses returned to baseline soundness within 24 h of reversing lameness.
Treatment with single-dose IV administration of t-TUCB improved lameness induced by the a-HSB, suggesting that t-TUCB has anti-nociceptive effects in horses.
The soluble epoxide hydrolase inhibitor, t-TUCB, is a promising novel analgesic for horses.
•Soluble epoxide hydrolase inhibitors attenuate nociceptive pain in horses.•No adverse reactions were observed following intravenous administration of t-TUCB.•Plasma concentrations correlated with clinical effect of t-TUCB.
Some horses increase in forelimb lameness, measured as vertical head height asymmetry, or differences in maximums and minimums of head heights (HDmax, HDmin), after a palmar digital nerve (PDN) ...block. The prevalence of this finding, or what it means clinically, has not been reported in peer-reviewed literature.
To estimate the prevalence of increasing head height asymmetry after a PDN block and determine if this is associated with cause of forelimb lameness.
Retrospective case series.
Head height asymmetry, normalised to expected vertical head displacement, from inertial-sensor data collections of all horses evaluated for forelimb lameness while trotting in a straight line at two different clinics were screened for cases that had an initial PDN block and then another more proximal block in the same limb during the same lameness evaluation. Medical records of the screened cases (n = 213) were evaluated to determine the cause of lameness. Prevalence of increasing head height asymmetry was calculated. Differences in lameness amplitude between groups of cases that remained unchanged (Group 1), that increased (Group 2), and that decreased (Group 3) in head height asymmetry before and after the initial PDN block were compared (Kruskal-Wallis). Determination of the location of the cause of lameness and final diagnoses of cases were compared between Group 1 and Group 2 (chi-squared tests of independence).
The PDN block increased head height asymmetry at a prevalence of 32.5% (95% CI = 24.5%-41.5%) and 13.8% (95% CI = 7.3%-22.9%), in clinic 1 and 2, respectively. Increasing head height asymmetry after an initial PDN block did not predict localization of the cause of forelimb lameness or specific diagnosis (p = 0.1), other than indicating that it is unlikely to be in the foot (p = 0.02).
Study samples consisted primarily of Warmbloods (clinic 1) and Quarter Horses (clinic 2). Analysis of blocking induced changes was limited to straight line trot only.
Increasing head height asymmetry after PDN block is common during forelimb lameness evaluations. Other than indicating that the cause of lameness is more proximal in the blocked forelimb, this does not help determine the final diagnosis.
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