Fatigue-Related Changes in Running Technique and Mechanical Variables After a Maximal Incremental Test in Recreational Runners.

Understanding the changes in running mechanics caused by fatigue is essential to assess its impact on athletic performance. Changes in running biomechanics after constant speed conditions are well documented, but the adaptive responses after a maximal incremental test are unknown. We compared the spatiotemporal, joint kinematics, elastic mechanism, and external work parameters before and after a maximal incremental treadmill test. Eighteen recreational runners performed 2-minute runs at 8 km·h-1 before and after a maximal incremental test on a treadmill. Kinematics, elastic parameters, and external work were determined using the OpenCap and OpenSim software. We did not find differences in spatiotemporal parameters and elastic parameters (mechanical work, ankle, and knee motion range) between premaximal and postmaximal test conditions. After the maximal test, the runners flexed their hips more at contact time (19.4°-20.6°, P = .013) and presented a larger range of pelvis rotation at the frontal plane (10.3°-11.4°, P = .002). The fatigue applied in the test directly affects pelvic movements; however, it does not change the lower limb motion or the spatiotemporal and mechanical work parameters in recreational runners. A larger frontal plane motion of the pelvis deserves attention due to biomechanical risk factors associated with injuries.

Energetic responses of head-out water immersion at different temperatures during post-exercise recovery and its consequence on anaerobic mechanical power.

PURPOSE: While exercise recovery may be beneficial from a physiological point of view, it may be detrimental to subsequent anaerobic performance. To investigate the energetic responses of water immersion at different temperatures during post-exercise recovery and its consequences on subsequent anaerobic performance, a randomized and controlled crossover experimental design was performed with 21 trained cyclists. METHOD: Participants were assigned to receive three passive recovery strategies during 10 min after a Wingate Anaerobic Test (WAnT): control (CON: non-immersed condition), cold water immersion (CWI: 20 â„ƒ), and hot water immersion (HWI: 40 â„ƒ). Blood lactate, cardiorespiratory, and mechanical outcomes were measured during the WAnT and its recovery. Time constant (τ), asymptotic value, and area under the curve (AUC) were quantified for each physiologic parameter during recovery. After that, a second WAnT test and 10-min recovery were realized in the same session. RESULTS: Regardless the water immersion temperature, water immersion increased [Formula: see text] (+ 18%), asymptote ([Formula: see text]+ 16%, [Formula: see text] + 13%, [Formula: see text] + 17%, HR + 16%) and AUC ([Formula: see text]+ 27%, [Formula: see text] + 18%, [Formula: see text] + 20%, HR + 25%), while decreased [Formula: see text] (- 33%). There was no influence of water immersion on blood lactate parameters. HWI improved the mean power output during the second WAnT (2.2%), while the CWI decreased 2.4% (P < 0.01). CONCLUSION: Independent of temperature, water immersion enhanced aerobic energy recovery without modifying blood lactate recovery. However, subsequent anaerobic performance was increased only during HWI and decreased during CWI. Despite higher than in other studies, 20 °C effectively triggered physiological and performance responses. Water immersion-induced physiological changes did not predict subsequent anaerobic performance.

Transfer of strength training to running mechanics, energetics, and efficiency.

To examine the effects of increased strength on mechanical work, the metabolic cost of transport (Cost), and mechanical efficiency (ME) during running. Fourteen physically active men (22.0 ± 2.0 years, 79.3 ± 11.1 kg) were randomized to a strength-training group (SG, n = 7), who participated in a maximal strength training protocol lasting 8 weeks, and a control group (CG, n = 7), which did not perform any training intervention. Metabolic and kinematic data were collected simultaneously while running at a constant speed (2.78 m·s-1). The ME was defined as the ratio between mechanical power (Pmec) and metabolic power (Pmet). The repeated measures two-way ANOVA did not show any significant interaction between groups, despite some large effect sizes (d): internal work (Wint, p = 0.265, d = -1.37), external work (Wext, p = 0.888, d = 0.21), total work (Wtot, p = 0.931, d = -0.17), Pmec (p = 0.917, d = -0.17), step length (SL, p = 0.941, d = 0.24), step frequency (SF, p = 0.814, d = -0.18), contact time (CT, p = 0.120, d = -0.79), aerial time (AT, p = 0.266, d = 1.12), Pmet (p = 0.088, d = 0.85), and ME (p = 0.329, d = 0.54). The exception was a significant decrease in Cost (p = 0.047, d = 0.84) in SG. The paired t-test and Wilcoxon test only detected intragroup differences (pre- vs. post-training) for SG, showing a higher CT (p = 0.041), and a lower Cost (p = 0.003) and Pmet (p = 0.004). The results indicate that improved neuromuscular factors related to strength training may be responsible for the higher metabolic economy of running after 8 weeks of intervention. However, this process was unable to alter running mechanics in order to indicate a significant improvement in ME.

Vertical ground reaction force responses to different head-out aquatic exercises performed in water and on dry land.

The purpose was to analyse the vertical ground reaction forces (Fz) of head-out aquatic exercises [stationary running (SR), frontal kick (FK), cross-country skiing (CCS), jumping jacks (JJ), adductor hop (ADH) and abductor hop (ABH)] at two cadences in both aquatic and dry land environments. Twelve young women completed two sessions in each environment, each consisting of three exercises performed at two cadences (first and second ventilatory thresholds - C1 and C2, respectively). Two-way and three-way repeated measures analysis of variance were used to the statistical analysis. The results showed that the peak Fz and impulse were significantly lower in the aquatic environment, resulting in values from 28.2% to 58.5% and 60.4% to 72.8% from those obtained on dry land, respectively. In the aquatic environment, the peak Fz was lower and the impulse was higher at the C1 than at the C2. Furthermore, it was observed that SR and FK (0.9-1.1 BW) elicited a significantly higher peak Fz values compared to the ADH and JJ exercises (0.5-0.8 BW). It can be concluded that the aquatic environment reduces the Fz during head-out aquatic exercises. It should be noted that its magnitude is also dependent on the intensity and the identity of the exercise performed.

Comparison of COSMED'S FitMate™ and K4b2 metabolic systems reliability during graded cycling exercise.

This study compared the reliability of the Cosmed FitMate™ and K4b2 metabolic systems during light to heavy steady state exercise. Expired gas, ventilation were recorded in 50 subjects, using in a random order among four sessions, either the FitMate™ or the Cosmed K4b2. No differences in oxygen consumption were observed between the two systems whatever the intensity. Intraclass correlation were high for both analyzers (respectively for the FitMate™ system and the Cosmed K4b2; ICC: 0.76-0.88 vs. 0.88-0.95). The FitMate™ metabolic system could be a useful reliable and easy-to-use metabolic system in energy expenditure measurement.

Maximal and ventilatory thresholds cardiorespiratory responses to three water aerobic exercises compared with treadmill on land.

The purpose of this study was to compare the cardiorespiratory responses of young women to exercise at the first ventilatory threshold (VT1), the second ventilatory threshold (VT2), and at maximum effort (MAX) between maximal incremental tests performed using water aerobic exercises and a treadmill on land (TL). Twenty women (24.0 ± 2.5 years; 163.3 ± 6.7 cm; 60.0 ± 6.7 kg) underwent 4 maximal tests in randomized order, with a 48-hour interval between tests. Three tests involved performing water aerobic exercises (stationary running, frontal kick, and cross-country skiing) and 1 TL. Oxygen uptake (VO2), ventilation (VE), and heart rate were measured throughout the tests, and their values at the VT1, VT2, and MAX intensities were determined by 3 independent, experienced physiologists. Repeated measures analysis of variance with Bonferroni post hoc tests were used for comparisons between tests (α = 0.05). Heart rate was significantly higher in the TL condition compared with the water aerobic exercises at the VT1 (p = 0.001), VT2 (p < 0.001), and MAX (p < 0.001) intensities. VO2 and VE had similar values across the 4 protocols at the VT1 intensity, but significantly higher values were observed with TL (VO2: p < 0.001; VE: p < 0.001) at the VT2 intensity. At the MAX intensity, VO2 was significantly higher with TL compared with the 3 water aerobic exercises (p < 0.001), whereas no significant differences in VE between the 4 protocols were found. These results suggest that the prescription of water aerobics classes should be based on specific maximal tests for water aerobic exercises. Training intensities could be overestimated if they were based on maximal tests on dry land.

Association of Physical and Emotional Parameters with Performance of Firefighters: A Systematic Review.

Firefighting requires a high level of physical fitness and causes substantial psychological stress, engendering musculoskeletal, mental, and cardiac issues. Consequently, it is necessary to measure the preparation of the firefighters daily through the Firefighting Physical Ability Tests (FPATs). According to the literature, some variables are more important for performance in the FPAT. Therefore, we aimed to summarize evidence that relates physical and mental aspects to the FPAT performance. We used the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) method, screening 1055 records from databases and selecting 15 that met inclusion criteria. No emotional and psychological variables were correlated with the FPAT. Most research shows significant correlations between the FPAT performance and the following: aerobic fitness, upper body endurance and strength, anaerobic capacity, body fat, and age. Lower body endurance and strength, as well as anaerobic power, had a low number of investigations and need to be further explored. Abdominal endurance showed weak correlations, while flexibility did not show any correlations in most studies, although these should be considered for injury prevention. We recommend that fitness programs and evaluations include a global analysis considering the evidence presented for methodological improvements.

Biomechanical, physiological and anthropometrical predictors of performance in recreational runners.

Background: The maximal running speed (VMAX) determined on a graded treadmill test is well-recognized as a running performance predictor. However, few studies have assessed the variables that predict VMAX in recreationally active runners. Methods: We used a mathematical procedure combining Fick's law and metabolic cost analysis to verify the relation between (1) VMAX versus anthropometric and physiological determinants of running performance and, (2) theoretical metabolic cost versus running biomechanical parameters. Linear multiple regression and bivariate correlation were applied. We aimed to verify the biomechanical, physiological, and anthropometrical determinants of VMAX in recreationally active runners. Fifteen recreationally active runners participated in this observational study. A Conconi and a stead-steady running test were applied using a heart rate monitor and a simple video camera to register the physiological and mechanical variables, respectively. Results: Statistical analysis revealed that the speed at the second ventilatory threshold, theoretical metabolic cost, and fat-mass percentage confidently estimated the individual running performance as follows: VMAX = 58.632 + (-0.183 * fat percentage) + (-0.507 * heart rate percentage at second ventilatory threshold) + (7.959 * theoretical metabolic cost) (R2 = 0.62, p = 0.011, RMSE = 1.50 km.h-1). Likewise, the theoretical metabolic cost was significantly explained (R2 = 0.91, p = 0.004, RMSE = 0.013 a.u.) by the running spatiotemporal and elastic-related parameters (contact and aerial times, stride length and frequency, and vertical oscillation) as follows: theoretical metabolic cost = 10.421 + (4.282 * contact time) + (-3.795 * aerial time) + (-2.422 * stride length) + (-1.711 * stride frequency) + (0.107 * vertical oscillation). Conclusion: Critical determinants of elastic mechanism, such as maximal vertical force and vertical and leg stiffness were unrelated to the metabolic economy. VMAX, a valuable marker of running performance, and its physiological and biomechanical determinants can be effectively evaluated using a heart rate monitor, treadmill, and a digital camera, which can be used in the design of training programs to recreationally active runners.

Maximal and ventilatory thresholds of oxygen uptake and rating of perceived exertion responses to water aerobic exercises.

This study aimed to compare the V[Combining Dot Above]O2max and first and second ventilatory threshold (1stVT and 2ndVT) V[Combining Dot Above]O2 values and rating of perceived exertion (RPE) responses of treadmill running (TR) with those of 3 water aerobic exercises: stationary running (SR), jumping jack (JJ), and forward kick (FK). Nine women (22.89 ± 1.81 years, 1.66 ± 0.07 m, 58.46 ± 4.19 kg) performed 1 maximal test session for each of the 4 exercise protocols in a randomized order to determine the V[Combining Dot Above]O2max and V[Combining Dot Above]O2 values and RPE responses corresponding with the 1stVT and 2ndVT. V[Combining Dot Above]O2 values were also expressed as a percentage of V[Combining Dot Above]O2max (%V[Combining Dot Above]O2max). A repeated measures analysis of variance and Bonferroni's post hoc test were used, with α = 0.05 denoting statistical significance. The analyses showed that the V[Combining Dot Above]O2 responses were significantly higher for TR than for the other exercises at all effort intensities (V[Combining Dot Above]O2max: p < 0.001; 1stVT and 2ndVT V[Combining Dot Above]O2: p < 0.001), followed by intermediate responses for SR and FK and lower responses for JJ. However, no significant differences between exercises for values of %V[Combining Dot Above]O2max (1stVT: p = 0.099; 2ndVT: p = 0.131) and RPE (1stVT: p = 0.275; 2ndVT: p = 0.477) were found at submaximal intensities, indicating that it is possible to achieve and maintain the same training intensity with these exercises during a typical water fitness lesson. Moreover, the RPE values obtained for the 1stVT and 2ndVT can make the prescription of intensity for these water exercises for young women more simple and practical.

Modelling 5-km Running Performance on Level and Hilly Terrains in Recreational Runners.

Incline and level running on treadmills have been extensively studied due to their different cardiorespiratory and biomechanical acute responses. However, there are no studies examining the performance determinants of outdoor running on hilly terrains. We aimed to investigate the influence of anthropometrics, muscle strength, and cardiorespiratory and gait spatiotemporal parameters during level (0%) and inclined (+7%) running on performance in level and hilly 5-km races. Twenty male recreational runners completed two 5-km outdoor running tests (0% vs. +7% and −7%), and two submaximal (10 km·h−1) and incremental treadmill tests at 0 and 7% slopes, after complete laboratory evaluations. The velocity at maximal oxygen consumption (VO2max) evaluated at 7% incline and level treadmill running were the best performance predictors under both hilly (R2 = 0.72; p < 0.05) and level (R2 = 0.85; p < 0.01) conditions, respectively. Inclusion of ventilatory and submaximal heart rate data improved the predictive models up to 100%. Conversely, none of the parameters evaluated in one condition contributed to the other condition. The spatiotemporal parameters and the runners' strength levels were not associated to outdoor performances. These results indicate that the vVO2max evaluated at similar slopes in the lab can be used to predict 5-km running performances on both level and hilly terrains.

Cardiorespiratory, neuromuscular and kinematic responses to stationary running performed in water and on dry land.

The purpose of this study was to analyze the cardiorespiratory, neuromuscular and kinematic responses obtained during the stationary running in aquatic and dry land environments. Twelve women took part in the experimental protocol. Stationary running was performed for 4 min at three submaximal cadences and for 15 s at maximal velocity, with the collection of kinematic (peak hip angular velocity (AV)), cardiorespiratory (oxygen uptake (VO(2))) and neuromuscular variables (electromyographic (EMG) signal from the rectus femoris (RF), vastus lateralis (VL), semitendinosus (ST) and short head of the biceps femoris (BF) muscles) in land-based and water-based test protocols. Factorial ANOVA was used, with an alpha level of 0.05. AV was significantly higher when the exercise was performed on land, and became significantly higher as the execution cadence increased. Similarly, VO(2) was significantly higher in the land-based exercise and rose as cadence increased. With the increase in the submaximal execution cadences, there was no corresponding increase in the EMG signal from the VL, BF, RF and ST muscles in either environment, though such a significantly increase was seen between the submaximal cadences and the maximal velocity. Dry land presented significantly greater EMG signal responses for all muscles at the submaximal cadences, except for the ST muscle. However, at the maximal velocity, all the analyzed muscle groups showed similar responses in both environments. In summary, for both environments, cardiorespiratory responses can be maximized by increasing the submaximal cadences, while neuromuscular responses are only optimized by using maximal velocity.

Correlation between rating of perceived exertion and physiological variables during the execution of stationary running in water at different cadences.

The purpose of the present study was to correlate the rating of perceived exertion (RPE) with cardiorespiratory and neuromuscular variables during the execution of stationary running in water at different cadences. The sample consisted of 12 apparently healthy women (age: 22.33 ± 0.57 years). During the assessment session, the subjects performed the stationary running exercise in water at 3 different cadences: 60, 80, and 100 bpm. The heart rate (HR), oxygen uptake (V(O2)), ventilation (Ve), and electromyographic (EMG) signal of the vastus lateralis (VL), biceps femoris (BF), rectus femoris (RF), and semitendinosus (ST) muscles were measured during the exercise, and the overall body RPE was measured immediately following the end. Pearson's linear correlation and multiple linear regression were used, with p < 0.05. The analyses demonstrate a high and significant relationship between RPE and HR (r = 0.65; p < 0.001), RPE and %HR maximal (r = 0.65; p < 0.001), RPE and V(O2) (r = 0.60; p = 0.001), RPE and %V(O2) maximal (r = 0.71; p < 0.001), and RPE and Ve (r = 0.77; p < 0.001). However, there was no relationship between the RPE and the EMGs of the VL, BF, RF, and ST muscles. With regard to the regression, the model was significant (p < 0.001) with an r2 = 0.79, whereas the variables that explained better the RPE were %V(O2) maximal and Ve. Hence, these results suggest an association between the perception of exertion and cardiorespiratory variables, which was not the case with the neuromuscular variables evaluated in this study. Therefore, the Borg scale of RPE can be used when prescribing stationary running exercise in water for young women.

Effects of strength, endurance, and concurrent training on aerobic power and dynamic neuromuscular economy in elderly men.

The aim of this study was to investigate the effects of concurrent training on endurance capacity and dynamic neuromuscular economy in elderly men. Twenty-three healthy men (65 ± 4 years) were divided into 3 groups: concurrent (CG, n = 8), strength (SG, n = 8), and aerobic training group (EG, n = 7). Each group trained 3 times a week for 12 weeks, strength training, aerobic training, or both types of training in the same session. The maximum aerobic workload (Wmax) and peak oxygen uptake (VO2peak) of the subjects were evaluated on a cycle ergometer before and after the training period. Moreover, during the maximal test, muscle activation was measured at each intensity by means of electromyographic signals from the vastus lateralis (VL), rectus femoris (RF), biceps femoris long head, and gastrocnemius lateralis to determine the dynamic neuromuscular economy. After training, significant increases in VO2peak and Wmax were only found in the CG and EG (p < 0.05), with no difference between groups. Moreover, there was a significant decrease in myoelectric activity of the RF muscle at 50 (EG), 75 and 100 W (EG and CG) and in the VL for the 3 groups at 100 W (p < 0.05). No change was seen in the electrical signal from the lateral gastrocnemius muscle and biceps femoris. The results suggest specificity in adaptations investigated in elderly subjects, because the most marked changes in the neuromuscular economy occurred in the aerobically trained groups.

Neuromuscular economy, strength, and endurance in healthy elderly men.

Declines in muscular strength resulting from reduced neural activity may influence the reduction in aerobic capacity in older men. However, there has been little investigation into the relationship between muscular strength and economy of movement during aerobic exercise in elderly subjects. Thus, the purpose of this study was to investigate the possible relationship between strength, aerobic performance, and neuromuscular economy in older men. Twenty-eight aged men (65 ± 4 years old) were evaluated in dynamic (1 repetition maximum test), isometric strength (maximal voluntary contraction), and rate of force development. Peak oxygen uptake, maximal workload, and ventilatory threshold were determined during a ramp protocol on a cycle ergometer. Throughout the same protocol, the neuromuscular economy (electromyographic signal) of the vastus lateralis was measured. Significant correlations were found between muscular strength, cardiorespiratory fitness, and neuromuscular economy (r = 0.43-0.64, p < 0.05). Our results suggest that cardiorespiratory capacity and economy of movement are associated with muscular strength during aging.

Validity of differentiated ratings of perceived exertion for use during aquatic cycling.

BACKGROUND: Although aquabiking has become widespread, the assessment of the intensity for aquatic cycling remains poorly defined. METHODS: This study investigated the validity of differentiated ratings of perceived exertion (dRPE) recorded from the chest (RPE-chest) and legs (RPE-legs) during aquatic cycling and aimed to determine a simple and accurate estimate of dRPE to regulate aquabiking. Twelve active young subjects performed a pedaling task on an immersed ergocycle using randomly imposed cycling cadences ranging from 50 to 100 rpm in 3-minute steps interspersed by 3-minute active recovery periods. dRPE and cardiorespiratory responses (heart rate [HR]; percentage of heart rate peak value [%HRpeak]; oxygen uptake [V̇O2]; and percentage of peak oxygen uptake [%V̇O2peak]) were measured during the last minute of each level. RESULTS: The data described three-step relationships between dRPE and rpm. RPE-chest and RPE-legs increased linearly only for cadences between 60 and 90 rpm (r=0.81 and r=0.88, respectively; P<0.001). At these cadences, significant relationships were also observed between dRPE and all the physiological data (highest Pearson product moment for %V̇O2peak: 0.81 for RPE-chest and 0.88 for RPE-legs, P<0.0001). Last, the classic signal dominance from the legs was observed (RPE-legs>RPE-chest, P<0.0001) but was reduced compared with data obtained during dryland cycling, suggesting a modulating effect of the aquatic medium. CONCLUSIONS: Cycling cadence was the better estimator of RPE-legs, which seemed to be the more appropriate dRPE to regulate the intensity of aquabiking in a safe range of pedaling rates.

Female students are the most psychologically affected by the COVID-19 outbreak: a case study in an academic community in Brazil.

OBJECTIVE: The study evaluates psychological responses to the COVID-19 outbreak in the students, professors, and staff due to the social distancing and transition of the classroom activities through online learning. METHODS: 518 participants from a University community in Brazil answered an online survey with questions related to demographic data, psychological responses, and preventive measures. Absolute and relative frequencies described the sample, Chi-square and z-test tested associations between the variables, adopting p<0.05. RESULTS: Female (71.20%), young age -18 to 35 years (82.60%), students (76.10%), living in a family with 1 to 3 members during quarantine (55.40%) were more prevalent respondents. Women, young age, and students had a significantly higher rate of negative feelings in all psychological questions. Curiously, negative feelings during social distances affect the participants, independent of living quarantine alone or with family/friends during the COVID-19 outbreak. CONCLUSIONS: Our findings demonstrated that the COVID-19 outbreak affected the psychological responses in the Brazilian academic community, also, women, young age, and students appear to be a risk group to negative psychological responses. The long-term quarantine due to the COVID-19 pandemic may cause further worsening in the psychological responses, especially in those in the risk group.

Characterization of Reproductive and Morphological Variables in Female Elite Futsal Players.

We aimed to characterize the age of onset of training, age at menarche, menstrual periodicity, and performance perception during the menstrual cycle and examined the impact of these reproductive variables on body composition, morphology, and body weight satisfaction in Brazilian elite futsal players. The study consisted of 115 female Brazilian elite futsal players from the top national teams. Data were collected during the twentieth Women's Brazil Futsal Cup. Players were interviewed and self-reported their age of onset of training, age at menarche, menstrual periodicity, and the menstrual period, where they performed best. We also asked for what they considered to be their ideal body weight as well as information related to their training (i.e., volume and frequency). Subsequently, anthropometric measurements (i.e., body mass, height, circumferences, diameters, and skinfold thickness) were performed to estimate the body composition and determine morphological characteristics (e.g., somatotype). Fifty-nine (53.2%) players were postmenarche-trained and 52 (46.8%) were premenarche-trained. Eighteen (16.2%), 65 (58.6%), and 28 (25.2%) were classified as early, normal, and late menarche, respectively. Only 11 (9.6%) and 1 (0.9%) had irregular menstrual cycles and were amenorrheic, respectively. Seventy-three (69.5%), 23 (21.9%), and 9 (8.6%) reported that their game performance was the best at the follicular phase, menses, and luteal phase of the menstrual cycle, respectively. No associations between the four reproductive-related variables were found. Postmenarche-trained players had significant lower age at menarche and higher percentage body fat. The somatotype profile registered lower ectomorphy rate for the postmenarche-trained participants after controlling for covariates. Early menarche group presented higher sum of six skinfold thickness and endomorphy rate compared to normal and late menarche groups. No differences were found when menstrual periodicity groups and best performance groups were compared, except for higher femur width in the regular menstrual cycle group compared to the irregular one. The association between body weight satisfaction and the four reproductive-related variables were not observed. Premenarche-trained Brazilian elite futsal players had the menarche later than the postmenarche-trained athletes. Most of the participants had menarche age classified as "normal," presented "regular" menstrual cycles and perceived to perform better during the follicular phase of the menstrual cycle.

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.

Perceived exertion in different strength exercise loads in sedentary, active, and trained adults.

The aim was to analyze the relationship between the perceived exertion (PE) and different loads in strength exercises (SEs), in sedentary, active, and trained adult subjects. Thirty young men (18-34 years) were divided into 3 groups (experimental group [EG]): sedentary EG (SEG), physically active group (PAG), and the strength trained group (STG). Maximum strength was established using the 1 repetition maximum test (1RM). Using series of 12 repetitions, different loads were applied until the 4 ratings of PE (RPEs) (11, 13, 15, and 17) from 15 category Borg Perceived Exertion Scale (RPE 6-20). The pace of the repetitions and the intervals between the sets were controlled, the loads were blind, the order of the RPE randomized, whereas the PE was localized and determined after completion of the series. Strength correlations between the RPE and the %1RM, according to the EGs and SEs (0.826-0.922, p < 0.001), were observed. Similar behavior was seen in the SEs. Higher loads are related to higher RPEs and are differentiated between the EGs. The STG used higher %1RM when compared to the SEG, whereas the PAG, displayed an intermediary behavior in relation to the other groups. The use of PE represents a reliable instrument for the measurement of intensity in strength training.

Short Trail Running Race: Beyond the Classic Model for Endurance Running Performance.

PURPOSE: This study aimed to examine the extent to which the classical physiological variables of endurance running performance (maximal oxygen uptake (V˙O2max), %V˙O2max at ventilatory threshold (VT), and running economy (RE)) but also muscle strength factors contribute to short trail running (TR) performance. METHODS: A homogeneous group of nine highly trained trail runners performed an official TR race (27 km) and laboratory-based sessions to determine V˙O2max, %V˙O2max at VT, level RE (RE0%) and RE on a +10% slope, maximal voluntary concentric and eccentric knee extension torques, local endurance assessed by a fatigue index (FI), and a time to exhaustion at 87.5% of the velocity associated with V˙O2max. A simple regression method and commonality analysis identifying unique and common coefficients of each independent variable were used to determine the best predictors for the TR race time (dependent variable). RESULTS: Pearson correlations showed that FI and V˙O2max had the highest correlations (r = 0.91 and r = -0.76, respectively) with TR performance. The other selected variables were not significantly correlated with TR performance. The analysis of unique and common coefficients of relative V˙O2max, %V˙O2max at VT, and RE0% provides a low prediction of TR performance (R = 0.48). However, adding FI and RE on a +10% slope (instead of RE0%) markedly improved the predictive power of the model (R = 0.98). FI and V˙O2max showed the highest unique (49.8% and 20.4% of total effect, respectively) and common (26.9% of total effect) contributions to the regression equation. CONCLUSIONS: The classic endurance running model does not allow for meaningful prediction of short TR performance. Incorporating more specific factors into TR such as local endurance and gradient-specific RE testing procedures should be considered to better characterize short TR performance.