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.

Acute ventilatory responses to swimming at increasing intensities.

Background: Physical exercise is a source of stress to the human body, triggering different ventilatory responses through different regulatory mechanisms and the aquatic environment imposes several restrictions to the swimmer, particularly regarding the restricted ventilation. Thus, we aimed to assess the acute ventilatory responses and to characterize the adopted breathing patterns when swimming front crawl at increasing intensity domains. Methods: Eighteen well-trained swimmers performed 7 × 200 m front crawl (0.05 m∙s-1 velocity increments) and a maximal 100 m (30 s rest intervals). Pulmonary gas exchange and ventilation were continuously measured (breath-by-breath) and capillary blood samples for lactate concentration ([La-]) analysis were collected at rest, during intervals and at the end of the protocol, allowing the identification of the low, moderate, heavy, severe and extreme intensity domains. Results: With the swimming velocity rise, respiratory frequency (f R), [La-] and stroke rate (SR) increased ([29.1-49.7] breaths∙min-1, [2.7-11.4] mmol∙L-1, [26.23-40.85] cycles; respectively) and stroke length (SL) decreased ([2.43-2.04] m∙min-1; respectively). Oxygen uptake (VO2), minute ventilation (VE), carbon dioxide production (VCO2) and heart rate (HR) increased until severe ([37.5-53.5] mL∙kg-1∙min-1, [55.8-96.3] L∙min-1, [32.2-51.5] mL∙kg-1∙min-1 and [152-182] bpm; respectively) and stabilized from severe to extreme (53.1 ± 8.4, mL∙kg-1∙min-1, 99.5 ± 19.1 L∙min-1, 49.7 ± 8.3 mL∙kg-1∙min-1 and 186 ± 11 bpm; respectively) while tidal volume (VT) was similar from low to severe ([2.02-2.18] L) and decreased at extreme intensities (2.08 ± 0.56 L). Lastly, the f R/SR ratio increased from low to heavy and decreased from severe to the extreme intensity domains (1.12 ± 0.24, 1.19 ± 0.25, 1.26 ± 0.26, 1.32 ± 0.26 and 1.23 ± 0.26). Conclusions: Our findings confirm a different ventilatory response pattern at extreme intensities when compared to the usually evaluated exertions. This novel insight helps to understand and characterize the maximal efforts in swimming and reinforces the importance to include extreme efforts in future swimming evaluations.

Repeatability of ventilatory, metabolic and biomechanical responses to an intermittent incremental swimming protocol.

Objective. This study aimed to determine the repeatability of ventilatory, metabolic and biomechanical variables assessed at a large spectrum of front crawl swimming intensities. We hypothesized a strong agreement (combined with a small range of variation) between a typical step protocol performed in two experimental moments.Approach. Forty competitive swimmers performed a 7 × 200 m front crawl intermittent incremental protocol (0.05 m·s-1velocity rises and 30 s intervals) on two different occasions (48-72 h apart). Pulmonary gas exchange and ventilation were continuously measured breath-by-breath, metabolic variables were assessed during the intervals and biomechanical analysis was done at every protocol step.Main results. Concomitantly with the velocity increment, oxygen uptake, carbon dioxide production, ventilation, respiratory frequency, respiratory exchange ratio, averaged expiratory concentrations, end tidal oxygen and ventilatory equivalents for oxygen and carbon dioxide and blood lactate concentrations rose (p < 0.001), averaged expiratory concentrations and end tidal carbon dioxide and duration of inspiration, expiration and total breathing cycle decreased (p < 0.001), while tidal volume and volumes of oxygen and carbon dioxide expired maintained constant. Stroke frequency and stroke length increased and decreased (respectively) with the swimming velocity raise. No differences between experimental moments were observed in most of the assessed variables (p > 0.05), with a low dispersion (0.49%-9.94%) except for lactate concentrations and inspiration and expiration durations (11.00%-17.16%). Moderate-nearly perfect direct relationships and a good-excellent degree of reliability between moments were verified for all the assessed variables (r = 0.50-1.00, ICC = 0.76-1.00,p < 0.001), except for respiratory exchange ratio.Significance. The reliability analysis confirmed the repeatability of the assessed ventilatory, metabolic and biomechanical variables, with the obtained data well representing swimmers physiological condition when monitoring performance through a commonly used step protocol.

Residual effects of mental fatigue on subjective fatigue, reaction time and cardiac responses / Efectos residuales de la fatiga mental en la fatiga subjetiva, tiempo de reacción y respuestas cardíacas / Efeitos residuais da fadiga mental na fadiga subjetiva, tempo de reação e respostas cardíacas

This study investigated the residual effects of mental fatigue induced by the 30-minute incongruent Stroop Color Word task on subjectively perceived fatigue, reaction time, and heart rate variability (HRV) in 20 adult volunteers (10 men; 10 women). Dependent variables were assessed before, immediately after, and at 15, 30, 45, and 60 minutes after two conditions: (a) a 30-minute incongruent Stroop Color Word task (mental fatigue condition); or (b) a 30-minute control condition. At pre-testing, there were no significant differences between experimental conditions for any variable. However, there was a residual effect of mental fatigue on psychological responses for up to ~15 minutes after the experimental manipulation (p < 0.01). For the reaction time task, significant differences were observed only immediately after the mental fatigue, compared to the control condition (p < 0.0001). There were no significant differences between experimental conditions for any parameters of HRV at any testing period. In addition, there were no significant gender related differences at any period or in either condition for any variable. The data suggest that mental fatigue can alter psychological responses for up to ~15 min after its induction, and mental fatigue may impair cognitive reaction time performance without changing autonomic cardiac responses

Este estudio investigó los efectos residuales de la fatiga mental inducidos por 30 minutos Test de Stroop con palabra con color incongruente sobre la fatiga percibida subjetivamente, el tiempo de reacción y la variabilidad de la frecuencia cardíaca (HRV) en 20 voluntarios adultos (10 hombres, 10 mujeres). Las variables dependientes se evaluaron antes, inmediatamente después y a los 15, 30, 45 y 60 minutos después de dos condiciones: (a) Test de Stroop con palabra con color incongruente de 30 minutos (condición de fatiga mental); o (b) condición de control de 30 minutos. En la pre condiciones, no hubo diferencias significativas entre las condiciones experimentales para ninguna variable. Sin embargo, hubo un efecto residual de la fatiga mental en las respuestas psicológicas durante hasta ~ 15 minutos después de la manipulación experimental (p < 0,01). Para la tarea de tiempo de reacción, se observaron diferencias significativas solo inmediatamente después de la fatiga mental, en comparación con la condición de control (p < 0,0001). No hubo diferencias significativas entre las condiciones experimentales para ningún parámetro de HRV en ningún período. Además, no hubo diferencias significativas relacionadas con el género en ningún período ni en ninguna de las condiciones para ninguna variable. Los datos sugieren que la fatiga mental puede alterar las respuestas psicológicas hasta ~ 15 min después de su inducción, y la fatiga mental puede afectar el rendimiento del tiempo de reacción cognitiva sin cambiar las respuestas cardíacas autónomas

Este estudo investigou os efeitos residuais da fadiga mental induzida por 30 minutos do teste de Stroop com a palavra de cor incongruente na fadiga percebida de maneira subjetiva, tempo de reação e variabilidade da frequência cardíaca (VFC) em 20 voluntários adultos (10 homens; 10 mulheres). As variáveis dependentes foram avaliadas antes, imediatamente após e aos 15, 30, 45 e 60 minutos após duas condições: (a) teste de Stroop com a palavra de cor incongruente de 30 minutos (condição fadiga mental); ou (b) uma condição controle de 30 minutos. No pré-teste, não houve diferenças significativas entre as condições experimentais para qualquer variável. No entanto, houve um efeito residual da fadiga mental nas respostas psicológicas por até ~ 15 minutos após a manipulação experimental (p <0,01). Para o teste de tempo de reação, foram observadas diferenças significativas apenas imediatamente após a fadiga mental, em comparação com a condição controle (p <0,0001). Não houve diferenças significativas entre as condições experimentais para quaisquer parâmetros da VFC em qualquer período. Além disso, não houve diferenças significativas relacionadas ao gênero em qualquer período ou em qualquer condição para qualquer variável. Os dados sugerem que a fadiga mental pode alterar as respostas psicológicas por até 15 minutos após sua indução, e a fadiga mental pode prejudicar o desempenho cognitivo pela piora tempo de reação sem alterar as respostas autonômicas cardíacas

Effects of walk training with self-selected intensity on biochemical markers and anthropometric variables in women with obesity.

To evaluate the effects of 12-weeks of walk training with self-selected intensity on lipid profile and anthropometric variables in women with obesity. Forty-eight women volunteers with obesity were randomly assigned into two training groups: self-selected walking group (SSWG; n=25) and control group (CG; n=23). There was improvement in biochemical markers only in the SSWG post-intervention (p<0.05), however no changes were verified in anthropometric variables (p>0.05). This study demonstrates that walking at self-selected intensity improved the lipid profile in women with obesity.

Effects of Transcranial Direct Current Stimulation on Psychophysiological Responses to Maximal Incremental Exercise Test in Recreational Endurance Runners.

Previous studies have suggested that transcranial direct current stimulation (tDCS) might improve exercise performance and alter psychophysiological responses to exercise. However, it is presently unknown whether this simple technique has similar (or greater) effects on running performance. The purpose of this study was, therefore, to test the hypothesis that, compared with sham and cathodal tDCS, anodal tDCS applied over the M1 region would attenuate perception of effort, improve affective valence, and enhance exercise tolerance, regardless of changes in physiological responses, during maximal incremental exercise. In a double-blind, randomized, counterbalanced design, 13 healthy recreational endurance runners, aged 20-42 years, volunteered to participate in this study. On three separate occasions, the subjects performed an incremental ramp exercise test from rest to volitional exhaustion on a motor-driven treadmill following 20-min of brain stimulation with either placebo tDCS (sham) or real tDCS (cathodal and anodal). Breath-by-breath pulmonary gas exchange and ventilation and indices of muscle hemodynamics and oxygenation were collected continuously during the ramp exercise test. Ratings of perceived exertion (RPE) and affective valence in response to the ramp exercise test were also measured. Compared with sham, neither anodal tDCS nor cathodal tDCS altered the physiological responses to exercise (P > 0.05). Similarly, RPE and affective responses during the incremental ramp exercise test did not differ between the three experimental conditions at any time (P > 0.05). The exercise tolerance was also not significantly different following brain stimulation with either sham (533 ± 46 s) or real tDCS (anodal tDCS: 530 ± 44 s, and cathodal tDCS: 537 ± 40 s; P > 0.05). These results demonstrate that acute tDCS applied over the M1 region did not alter physiological responses, perceived exertion, affective valence, or exercise performance in recreational endurance runners.

Self-Selected Training Load and RPE During Resistance and Aerobic Training Among Recreational Exercisers.

This study compared training load and ratings of perceived exertion (RPE) during resistance training (RT) and aerobic training (AT) sessions at self-selected intensity. Participants were 54 recreationally trained subjects assigned to either RT or AT groups. During RT, participants performed three sets of 10 repetitions of each exercise at a self-selected intensity (load). After RT completion, participants performed one repetition maximum (1RM) and 10RM tests. During AT, participants performed a treadmill exercise at a self-selected intensity and duration (velocity and time). After AT completion, participants performed a treadmill maximal exercise test using a ramp protocol. During RT, subjects chose an intensity (43.6%-60.2% 1RM) below typical training recommendations, and RPE increased in successive exercise sets. During AT, participants chose an intensity (83.9% Heart Ratepeak) in line with typical training recommendations, and RPE increased from the first to second quartile of the session (from a mean of 3.9, standard deviation [ SD] = 1.7 to a mean of 5.4, SD = 1.7; p < .05) and remained stable thereafter. These recreationally trained participants self-selected lower RT intensities than are typically recommended for strength and hypertrophy increases (>67% 1RM) and AT intensities in line with typically recommended intensity (64%-95% HRmax) for cardiovascular fitness increases. Thus, for recreational trained individuals to perform RT at recommended intensities, specific instruction will be required.

ISOKINETIC ASSESSMENT OF MUSCULAR STRENGTH AND BALANCE IN BRAZILIAN ELITE FUTSAL PLAYERS.

PURPOSE/BACKGROUND: Strength asymmetries are related to knee injuries in intermittent sports players. The purpose of this study was to examine whether elite futsal players demonstrate strength asymmetries during knee isokinetic testing applying the Croisier et al.21 criteria. METHODS: Forty male elite (27.9 ± 6.5 years) Brazilian futsal players participated in the study. The testing protocol required players to perform concentric contractions of both quadriceps and hamstring muscles at angular velocities of 60 °·s-1 and 240 °·s-1 and eccentric contractions of hamstring at 30 °·s-1 and 120 °·s-1. Conventional (concentric:concentric) and mixed (eccentric:concentric) hamstrings/quadriceps (H/Q) ratios were calculated. Subjects were determined to have an imbalanced strength profile if an athlete had at least two parameters that were asymmetrical across speeds and conditions. Asymmetry was operationally defined as peak torque asymmetry greater than 15% in bilateral comparison, and H/Q ratio less than 0.47 for conventional and 0.80 for mixed conditions. RESULTS: Significant differences were observed between preferred and nonpreferred limbs in the concentric contractions of flexors at 240 °·s-1 and eccentric contractions of extensors and flexors at 30 °·s-1 and 120 °·s-1. However, these asymmetries did not exceed 15%. The conventional and mixed H/Q ratios were greater in the preferred than in nonpreferred limbs, but only the mixed hamstringsecc/quadricepsconc in the nonpreferred limbs showed values lower than recommended (<0.80). In addition, 50% of elite futsal players had preseason strength imbalances per the developed criteria. CONCLUSION: The studied elite futsal players had preseason strength imbalances, which may increase the risk of hamstring injuries. LEVEL OF EVIDENCE: 3.

Physiological, Perceptual, and Affective Responses to Six High-Intensity Interval Training Protocols.

This study examined the extent to which different high-intensity interval training (HIIT) and sprint interval training (SIT) protocols could influence psychophysiological responses in moderately active young men. Fourteen participants completed, in a randomized order, three cycling protocols (SIT: 4 × 30-second all-out sprints; Tabata: 7 × 20 seconds at 170% ⋮O2max; and HIIT: 10 × 60 seconds at 90% HRmax) and three running HIIT protocols (4 × 4 minutes at 90%-95% HRmax, 5 × at v⋮O2max, and 4 × 1,000 meters at a rating of perceived exertion (RPE) of 8, from the OMNI-Walk/Run scale). Oxygen uptake (⋮O2), heart rate, and RPE were recorded during each interval. Affective responses were assessed before and after each trial. The Tabata protocol elicited the highest ⋮O2 and RPE responses, and the least pleasant session-affect among the cycling trials. The v⋮O2max elicited the highest ⋮O2 and RPE responses and the lowest mean session-affect among the running trials. Findings highlight the limited application of SIT and some HIIT protocols to individuals with low fitness levels.

Effect of low dose, short-term creatine supplementation on muscle power output in elite youth soccer players.

BACKGROUND: To determine the effects of a low dose, short-term Creatine monohydrate (Cr) supplementation (0.03 g.kg.d-1 during 14 d) on muscle power output in elite youth soccer players. METHODS: Using a two-group matched, double blind, placebo-controlled design, nineteen male soccer players (mean age = 17.0 ± 0.5 years) were randomly assigned to either Cr (N = 9) or placebo (N = 10) group. Before and after supplementation, participants performed a 30s Wingate Anaerobic Test (WAnT) to assess peak power output (PPO), mean power output (MPO), fatigue index (FI), and total work. RESULTS: There were significant increases in both PPO and MPO after the Cr supplementation period (P ≤ 0.05) but not the placebo period. There were also significant increases in total work, but not FI, after the Cr supplementation and placebo periods (P ≤ 0.05). Notably, there were differences in total work between the Cr and placebo groups after (P ≤ 0.05) but not before the 14 d supplementation period. CONCLUSION: There is substantial evidence to indicate that a low-dose, short-term oral Cr supplementation beneficially affected muscle power output in elite youth soccer players.

Repeated sprint ability in soccer players: associations with physiological and neuromuscular factors.

BACKGROUND: The aim of this study was to examine the relationship between repeated sprint ability (RSA, 6×40 m [20+20 m] with 20-s recovery) and neuromuscular and aerobic fitness variables in male collegiate soccer players. METHODS: Twenty-six players (age 22.5±3.6 years) were tested on separate days for countermovement jump (CMJ), squat jump (SJ), and standing long jump (LJ), and for maximal oxygen consumption (V̇O2max), velocity at onset of blood lactate accumulation (vOBLA), maximal aerobic speed (vV̇O2max), and peak blood lactate concentration (peak [La]). They were also tested for best and mean times on a repeated shuttle sprint ability test. RESULTS: RSA best time (r=-0.73 and r=-0.54) and RSA mean sprint time (r=-0.69 and r=-0.62) were significantly (P<0.01) correlated with LJ and CMJ, respectively. Significant correlations (P<0.05) were also found between RSA mean sprint time and sprint decrement with vOBLA (r=-0.44) and peak [La] (r=0.47), respectively. CONCLUSIONS: This study showed that RSA performance had a large to very large association with the individual level of jump performance and to a smaller extent to aerobic fitness variables in male collegiate soccer players. Given this finding, lower limbs' explosive-strength performance should be regarded as a relevant factor for male soccer.

HOW MOTIVATIONAL AND CALM MUSIC MAY AFFECT THE PREFRONTAL CORTEX AREA AND EMOTIONAL RESPONSES: A FUNCTIONAL NEAR-INFRARED SPECTROSCOPY (fNIRS) STUDY.

Using functional near-infrared spectroscopy, the present study investigated how listening to differently valenced music is associated with changes in hemoglobin concentrations in the prefrontal cortex area, indicating changes in neural activity. Thirty healthy people (15 men; M age = 24.8 yr., SD = 2.4; 15 women; M age = 25.2 yr., SD = 3.1) participated. Prefrontal cortex activation, emotional responses (heart rate variability), and self-reported affective ratings were measured while listening to calm and motivational music. The songs were presented in a random counterbalanced order and separated by periods of white noise. Mixed-model repeated-measures analysis of variance (ANOVA) evaluated the relationships for main effects and interactions. The results showed that music was associated with increased activation of the prefrontal cortex area. For both sexes, listening to the motivational song was associated with higher vagal withdrawal (lower HR) than the calm song. As expected, participants rated the motivational song with greater affective valence and higher arousal. Effects persisted longer in men than in women. These findings suggest that both the characteristics of music and sex differences may significantly affect the results of emotional neuroimaging in samples of young adults.

How does music aid 5 km of running?

This research investigated the effects of music and its time of application on a 5-km run. Fifteen well-trained male long-distance runners (24.87 ± 2.47 years; 78.87 ± 10.57 kg; 178 ± 07 cm) participated in this study. Five randomized experimental conditions during a 5-km run on an official track were tested (PM: motivational songs, applied before 5 km of running; SM: slow motivational songs, applied during 5 km of running; FM: fast and motivational songs, applied during 5 km of running; CS: calm songs, applied after 5 km of running; CO: control condition). Psychophysiological assessments were performed before (functional near-infrared spectroscopy, heart rate variability [HRV], valence, and arousal), during (performance time, heart rate, and rate of perceived exertion [RPE]), and after (mood, RPE, and HRV) tests. The chosen songs were considered pleasurable and capable of activating. Furthermore, they activated the 3 assessed prefrontal cortex (PFC) areas (medial, right dorsolateral, and left dorsolateral) similarly, generating positive emotional consequences by autonomous system analysis. The first 800 m was accomplished faster for SM and FM compared with other conditions (p ≤ 0.05); moreover, there was a high probability of improving running performance when music was applied (SM: 89%; FM: 85%; PM: 39%). Finally, music was capable of accelerating vagal tonus after 5 km of running with CS (p ≤ 0.05). In conclusion, music was able to activate the PFC area, minimize perceptions, improve performance, and accelerate recovery during 5 km of running.

The Use of Session RPE to Monitor the Intensity of Weight Training in Older Women: Acute Responses to Eccentric, Concentric, and Dynamic Exercises.

The rating of perceived exertion (RPE) is ability to detect and interpret organic sensations while performing exercises. This method has been used to measure the level of effort that is felt during weight-training at a given intensity. The purpose of this investigation was to compare session RPE values with those of traditional RPE measurements for different weight-training muscle actions, performed together or separately. Fourteen women with no former weight-training experience were recruited for the investigation. All participants completed five sessions of exercise: familiarization, maximum force, concentric-only (CONC-only), eccentric-only (ECC-only), and dynamic (DYN = CONC + ECC). The traditional RPE method was measured after each series of exercises, and the session RPE was measured 30 min after the end of the training session. The statistical analyses used were the paired t-test, one-way analysis of variance, and repeated measures analysis of variance. Significant differences between traditional RPE and session RPE for DYN, CONC, and ECC exercises were not found. This investigation demonstrated that session RPE is similar to traditional RPE in terms of weight-training involving concentric, eccentric, or dynamic muscle exercises, and that it can be used to prescribe and monitor weight-training sessions in older subjects.

Effect of body mass index on affect at intensities spanning the ventilatory threshold.

The aim of this study was to compare acute affective responses at exercise intensities based on the ventilatory threshold between normal weight, overweight, and obese women. 66 sedentary women (22 in each Body Mass Index group) performed a maximal graded treadmill test to measure their maximal oxygen uptake and ventilatory thresholds. Affective valence was compared at intensities spanning the ventilatory threshold (below, at, and above threshold). Affective valence below ventilatory threshold did not differ among the Body Mass Index groups. The obese group had a lower affective response at ventilatory threshold and above ventilatory threshold than the normal weight and overweight groups; the latter two groups did not differ. The obese group had a lower affective response than the normal and overweight groups, which corresponds to a less pleasant experience. Exercise prescriptions for obese subjects targeting intensities below ventilatory threshold can provide a more pleasant experience and may facilitate exercise adherence.

Validation of the OMNI-cycle scale of perceived exertion in the elderly.

This study examined the concurrent and construct validity of the OMNI-Cycle Rating of Perceived Exertion (RPE) Scale, using elderly men and women. Seventy-six participants performed a load-incremented cycle-ergometer exercise test. Concurrent validity was determined by correlating OMNI-RPE responses with oxygen uptake, relative peak oxygen uptake, pulmonary ventilation, heart rate, respiratory rate, and respiratory-exchange ratio during a load-incremented cycle-ergometer protocol. Construct validity was established by correlating RPE derived from the OMNI-Cycle Scale with RPE from the Borg (6-20) Scale. Multilevel, mixed linear-regression models indicated that OMNI-RPE distributed as a significant (p < .05) positive linear function (r = .81-.92) for all physiological measures. OMNI-RPE was positively (p < .01) and linearly related to Borg-RPE in elderly men (r = .97) and women (r = .96). This study demonstrates both concurrent and construct validity of the OMNI-Cycle RPE Scale. These findings support the use of this scaling metric with elderly men and women to estimate RPE during cycle-ergometer exercise.

Gender-based differences in substrate use during exercise at a self-selected pace.

The aim of this study was to investigate gender-based differences in substrate use during exercise at a self-selected pace. Seventeen men and 17 women performed a maximal exercise test and a 20-minute bout of self-paced treadmill walking to determine carbohydrate and fat oxidation rates. Gas exchange measurements were performed throughout the tests, and stoichiometric equations were used to calculate substrate oxidation rates. For each individual, a best-fit polynomial curve was constructed using fat oxidation rate (g·min(-1)) vs. exercise intensity (percentage of maximal oxygen uptake, % VO(2)max). Each individual curve was used to obtain the following variables: maximal fat oxidation (MFO), the peak rate of fat oxidation measured over the entire range of exercise intensities; fat(max), the exercise intensity at which the MFO was observed; and fat(max) zone, range of exercise intensities with fat oxidation rates within 10% of fat oxidation rates at fat(max). Although the MFO was similar between genders, fat(max) was lower in men than in women. Similarly, the "low" and "high" borders of the fat(max) zone were lower in men than in women. During exercise at a self-selected pace, carbohydrate oxidation rates were greater in men than in women, despite no gender-based differences in fat oxidation rates. However, fat oxidation contribution to total energy expenditure (EE) was greater in women than in men, despite no gender-based differences in the exercise intensity. In conclusion, although both genders self-selected a similar exercise intensity, the contribution of fat oxidation to EE is greater in women than in men. Interestingly, both genders self-selected an exercise intensity that falls within the fat(max) zone.

Psychophysiological responses to self-paced treadmill and overground exercise.

UNLABELLED: Speculation exists that a positive affective response experienced during exercise may play an important role in predicting exercise adherence. Previous studies using self-paced exercise protocols have been associated with health benefits and pleasant experiences. However, all of these studies were conducted in laboratories, and consequently, the external validity of the findings may be questionable. PURPOSE: To determine whether environmental settings (treadmill vs overground) differentially influence physiological, perceptual, and affective responses to exercise at a self-selected pace. METHODS: Thirty-four individuals (17 men and 17 women) between 18 and 30 yr volunteered to participate in this study. During the orientation session, individuals underwent an initial screening, anthropometric measurements, and familiarization with the experimental procedures. Next, subjects underwent a maximal treadmill test. In the two experimental trials, participants performed 20-min bouts of treadmill and overground walking at a self-selected pace, which were completed in a counterbalanced order. At least 48 h separated experimental trials. RESULTS: Using repeated-measures ANOVA, overground walking speed was significantly faster than treadmill walking speed (P < 0.01) during the 20-min bout of self-paced exercise. However, exercise intensity (%VO2R and %HRR) and perceived exertion during the session of overground walking were significantly lower (P < 0.05) when compared with those during the treadmill session. In addition, affective valence was more positive during the session of overground walking than during the treadmill session (P < 0.01). CONCLUSIONS: These data extend previous findings by showing that environmental setting influences physiological, perceptual, and affective responses during exercise at a self-selected pace. Self-paced exercise performed over ground resulted in lower perceptual and more positive affective responses.