Differentiated perceptions of exertion: part II. relationship to local and central physiological responses

Differentiated ratings of perceived exertion in the legs and chest were compared to local and central physiological adjustments during submaximal cycle ergometer exercise. 50 male subjects performed three separate cycle ergometer tests. Power output was held constant at 840 kpm/min., while pedalling rate was randomly set at 40, 60, or 80 rpm. Differentiated reports of exertion from the legs were considered to be local signals and reports from the chest to be central signals. Ratings of exertion for the legs, chest and over-all body were each significantly higher at 40 rpm than 60 or 80 rpm. Heart rate, oxygen uptake, ventilation and respiratory rate were also higher at 40 rpm. Lactic acid, pH, and pCO2 were similar between pedalling rates. Lactic acid did not operate differentially to influence local perceptual signals from the legs. Central measures of respiratory and aerobic metabolic adjustments were consistent with the more intense regional report of chest exertion at 40 rpm.     

A method for the delivery of reinforcement during exercise

The purpose of this study was to develop an automated system for positively or negatively reinforcing subjects while they exercised on an electronically braked bicycle ergometer. The circuitry used to interface the subject’s pedal speed responses with the delivery of auditory reinforcement is presented, as well as a study designed to test the utility of the system. Twenty 18- to 25-year-old male subjects exercised on an electronically braked ergometer at a constant workload of 50 W for three 5-min blocks. During the first 5 min, subjects pedaled at their preferred rate, and during the next two 5-min blocks, they pedaled faster or slower than their baseline pedal speed to turn on a comedy tape for positive reinforcement, or turn off 90 dB of white noise for negative reinforcement. Circuits that interfaced the subject’s pedal response with the delivery of reinforcement are discussed in detail. Both positive and negative reinforcement increased the targeted pedaling rates, with no differences as a function of targeting increased or decreased pedal speed. This system could be used with various reinforcers, such as video and other audio equipment to increase exercise behavior.     

Learning to minimize energy costs and maximize mechanical work in a bimanual coordination task

The authors addressed the hypothesis that economy in motor coordination is a learning phenomenon realized by both reduced energy cost for a given workload and more external work at the same prepractice metabolic and attentional energy expenditure. "Self-optimization" of movement parameters has been proposed to reflect learned motor adaptations that minimize energy costs. Twelve men aged 22.3 -/+ 3.9 years practiced a 90 degrees relative phase, upper limb, independent ergometer cycling task at 60 rpm, followed by a transfer test of unpracticed (45 and 75 rpm) and self-paced cadences. Performance in all conditions was initially unstable, inaccurate, and relatively high in both metabolic and attentional energy costs. With practice, coordinative stability increased, more work was performed for the same metabolic and attentional costs, and the same work was done at a reduced energy cost. Self-paced cycling was initially below the metabolically optimal, but following practice at 60 rpm was closer to optimal cadence. Given the many behavioral options of the motor system in meeting a variety of everyday movement task goals, optimal metabolic and attentional energy criteria may provide a solution to the problem of selecting the most adaptive coordination and control parameters.     

Learning to Minimize Energy Costs and Maximize Mechanical Work in a Bimanual Coordination Task

The authors addressed the hypothesis that economy in motor coordination is a learning phenomenon realized by both reduced energy cost for a given workload and more external work at the same prepractice metabolic and attentional energy expenditure. "Self-optimization" of movement parameters has been proposed to reflect learned motor adaptations that minimize energy costs. Twelve men aged 22.3 ± 3.9 years practiced a 90° relative phase, upper limb, independent ergometer cycling task at 60 rpm, followed by a transfer test of unpracticed (45 and 75 rpm) and selfpaced cadences. Performance in all conditions was initially unstable, inaccurate, and relatively high in both metabolic and attentional energy costs. With practice, coordinative stability increased, more work was performed for the same metabolic and attentional costs, and the same work was done at a reduced energy cost. Selfpaced cycling was initially below the metabolically optimal, but following practice at 60 rpm was closer to optimal cadence. Given the many behavioral options of the motor system in meeting a variety of everyday movement task goals, optimal metabolic and attentional energy criteria may provide a solution to the problem of selecting the most adaptive coordination and control parameters.     

Differentiated perceptions of exertion: part I. mode of integration of regional signals

The mode of sensory integration of differentiated perceptions of exertion from the legs and chest was determined during sub-maximal cycle ergometer exercise. 50 male subjects performed three separate cycle ergometer tests. Power output was held constant at 840 kpm/min., while pedalling rate was randomly set at 40, 60, or 80 rpm. The over-all rating of perceived exertion was significantly lower than the rating for the legs and higher than that for the chest at each pedalling rate. Local signals from the legs dominated the sensory process. Central signals were less pronounced. The mean of the ratings for the legs and chest was slightly but significantly higher than the over-all rating at each pedalling rate. Therefore, the integration process at the superordinate level of sensory processing appeared as a weighted average of the involved regional signals.     

Relationship between ratings of perceived exertion and exercise-induced decrease in state anxiety

24 females (aged 18 to 28 yr.) completed two 24-min., randomly ordered bicycle ergometer exercise bouts at workloads maintaining steady state at 30% and 60% heart-rate reserve. Ratings of perceived exertion (RPE) were recorded at 3-min. intervals from Minutes 9 to 24 of exercise. State anxiety was measured prior to, immediately following and 50 min, after cessation of exercise. Regression analysis indicated no relationship between RPE and the pre- to postexercise changes in state anxiety.     

Influence of aerobic fitness on ratings of perceived exertion during light to moderate exercise

Based on scores from a maximal exercise test on a bicycle ergometer, 24 college-age women were classified into three aerobic-fitness groups. Each subject then completed two randomly ordered cycle exercise bouts at 1-wk. intervals. The exercise bouts required the subjects to pedal for 24 min. attaining and then maintaining a target heart rate of either 30% or 60% of heart-rate reserve. Ratings of perceived exertion (RPE) were reported at the end of each third minute of the exercise period. Repeated-measures analysis of variance indicated the RPE was significantly related to the exercise workload and duration of exercise. No main effect was found for fitness. Two-way interactions were detected for fitness x duration of exercise and for workload x duration of exercise.     

Focusing attention on circular pedaling reduces movement economy in cycling

Previous research has shown that focus of attention affects movement economy in endurance tasks. This experimental study was designed to take a closer look at how focusing attention on special characteristics of endurance cycling actions can influence metabolic energy costs. Twenty-five trained cyclists completed 4 × 6 min time trials at submaximal intensity on a cycling ergometer. For each of the four time trials, they were instructed to adopt a different focus of attention: (1) circular pedaling, (2) force production of quad muscles, (3) head position, (4) stimuli in a cycling video. The order of conditions was counterbalanced. The main dependent measure was movement economy (i.e., oxygen consumption at a given workload). The results show that a focus on the circular pedaling action leads to reduced economy than a focus on the video (p = 0.001). Focusing on smooth and circular pedaling includes a continuous monitoring of the cycling action, which could disturb the rhythmical nature of movement execution, thereby leading to detriments in movement economy.     

Reaction time unchanged in older women following aerobic training

The effect of aerobic exercise on reaction time in older women was investigated. 14 women (M age = 65 yr.) were carefully screened for health status and lifestyle, then assigned to a random order of the exercise and control groups (ns = 7). Pre- and posttraining tests of aerobic capacity, simple reaction time, and choice reaction time were administered. The exercise group rode a stationary bicycle ergometer for 8 consecutive weeks for 3 35- to 40-min. sessions per week. There were no significant pretraining differences between groups on simple reaction time, choice reaction time, or estimated VO2max. No posttraining differences for simple and choice reaction time were found even though the exercise group had a significantly higher VO2max than the controls. Contrary to some other findings, the data indicate that reaction time may be independent of aerobic training in healthy older women.     

Exertion–Attention–Flow Linkage Under Different Workloads

This study explored a proposed conceptual scheme examining the relationship between perceived exertion, flow, and the attention strategies of association and dissociation. After establishing a maximal baseline, 60 rowers performed at 30%, 50%, and 75% of maximal workloads for 10 min on a rowing ergometer. Results revealed that as workload increased, attention shifted from dissociation to association. Flow also showed a change in endorsement of the 9 dimensions. We found a main effect for gender, but not for experience. Women exhibited higher global flow than did men during the 75% and maximal sessions. Results lend preliminary support for the proposed conceptual scheme in which perceived effort affects attention focus and flow experience. Applied recommendations for coaches and athletes are presented.     

Effect of three levels of work intensity on performance of a fine motor skill.

The purpose of this study was to investigate the effect of three levels of work intensity on the performance of a fine motor skill during steady-state exercies. Subjects were administered a progressive bicycle ergometer test to exhaustion in order to determine maximum heart rate (HRmax). Following practice sessions on the pursuit rotor, subjects performed 3 different rides on a bicycle ergometer at 60, 75, and 90% of HRmax. The order to test administration was varied randomly in an attempt to control for sequential effects. Analysis of variance with repeated measures was used to determine differences in pursuit rotor performance by days and by levels of work intensity. No confounding of learning was noted. A significant F ratio (p less than .001) between work intensities showed that fine motor performance during steady-state exercise is affected by levels of work intensity.     

Development of a metabolic equation for the NuStep recumbent stepper in older adults

The purpose of this study was to develop an accurate metabolic equation for estimating steady-state oxygen consumption (VO2) during submaximal NuStep exercise. Adults (N = 40; M age = 64.0 yr., SD = 6.5; M height = 170.1 cm, SD = 9.1; M weight = 85.7 kg, SD = 19.9) performed two randomized testing sessions. Each session consisted of six stages with combinations of four workloads (1, 3, 5, and 7) at 3 cadences (60, 80, and 100 steps/min.). Multiple regression analysis to predict steady-state VO2 from NuStep workload (W), NuStep steps/min., and subject body mass resulted in the following model (R2 = .73): Steady-state VO2 = 3.5 + 0.016 (W* steps/min.) + 0.092 (steps/min.) - 0.053 (weight). The standard error of the estimate and total error for the prediction of steady-state VO2 under all NuStep workload conditions were 2.3 mL/kg/min. and 2.4 mL/kg/ min., respectively. The standard error of the estimate and total error values are similar to those previously reported in the literature regarding the accuracy of metabolic equations for other exercise modalities. These findings support the use of the equation developed to predict steady-state VO2 for NuStep exercise in older adult clientele.     

Psychological States Following Resistance Exercise of Different Workloads

This experiment was designed to examine the effect of resistance exercise of different workloads on subsequent psychological states. Participants, 54 undergraduate students (34 male, 20 female), were randomly assigned to one of three groups: (a) low workload resistance exercise (50% of 1 RM), (b) high workload resistance exercise (80% of 1RM), or (c) a no exercise control. Resistance exercise consisted of three sets of five repetitions for three free-weight exercises: the bench press, overhead press, and dumbbell row. Psychological state was indicated by the Exercise-Induced Feeling States Inventory (Gauvin & Rejeski, 1993) and was assessed prior to exercise and at 10, 25, and 40 min post exercise. Data were analyzed via a 3 (group) x 4 (time) ANOVA with repeated measures on the second factor. All exercise participants experienced an increased sense of revitalization, which persisted for a greater extent in low rather than high workload participants. None of the groups reported changes over time in positive engagement or tranquility. In addition, while exercise groups did report a reduction in physical exhaustion during recovery, this improvement did not differ from no exercise controls nor did it differ between exercise groups. Thus, weight lifting appears to result in a sense of revitalization, an effect whose duration may be impacted by exercise workload.     

Metabolic and attentional energy costs of interlimb coordination

The authors investigated metabolic and attentional energy costs as participants (N = 6) practiced in-phase, antiphase, and 90 degrees -phase cycling (order counterbalanced) on independent bicycle ergometers, with resistance (40 W/ergometer) and frequency (40 rpm) held constant. Coordination stabilized and became more accurate for all 3 cycling modes, as shown by measures of relative phase, but that collective variable could not account for other relevant attributes of the multifaceted motor behavior observed across the 3 coordination modes. In-phase and antiphase cycling were similar in stability and accuracy, but antiphase had the lowest metabolic and attentional energy costs. Because both homologous muscle action and perceptually symmetrical oscillations coincided in the in-phase mode, the absence of predominance of the inphase pattern showed that neither of those musculoskeletal and perceptual factors exclusively determined the strongest attractor of the coordination dynamics. Both metabolic and attentional costs declined with practice, consistent with the hypothesis that adaptive motor behavior is guided by sensory information concerning the energy demands of the task. Attentional cost was influenced not only by the information-processing demands of kinematic stability but also by the metabolic energy demands. Metabolic energy cost appeared to be the crucial determinant of the preferred solution for this coordination task.     

Cardiodynamic determinants of heart perception

Subjective perception of one's heartbeat is augmented by psychological factors (stress, fear) as well as by physiological influences (e.g., physical work). It is still unclear on which cardiac or circulatory parameters the "signal" for cardiac perception is based. In this study, the relation between cardiac performance and the ability to perceive one's heartbeat was investigated. Sixteen healthy subjects (8 female, 8 male, aged from 21 to 31 years) participated. Cardiac activity was varied by a combination of passive tilt and physical work on a bicycle ergometer. Subjects had to perform physical work (0, 25, 50, 75, 100 W) on the bicycle at seven different angles (90 degrees, 75 degrees, 60 degrees, 45 degrees, 30 degrees, 15 degrees, 0 degrees). A cardiac perception test was carried out after each load. The following cardiodynamic parameters were measured: stroke volume, contractility, and heart rate. The mean correlation coefficient between cardioceptive performance and cardiodynamic parameters was .62 for stroke volume, .45 for contractility, and .12 for heart rate. Obviously, a remarkable relation exists between the mass and--to a lesser degree--the velocity of ejected blood and cardiac perception. From this we infer, tentatively, that the subjectively perceivable heartbeat stimulus is generated by mechanical events that occur close to the left ventricle.     

EFFECTS OF A VARIABLE-RATIO REINFORCEMENT SCHEDULE WITH CHANGING CRITERIA ON EXERCISE IN OBESE AND NONOBESE BOYS

The effects of a variable-ratio schedule of reinforcement on pedaling a stationary exercise bicycle were examined. Three obese and three nonobese 11-year-old boys were individually tested five times weekly for approximately 12 weeks. A changing-criterion design was used in which each successive criterion was increased over mean performance rate in the previous phase by approximately 15%. The contingencies of the successive criteria resulted in systematic increases in rate of exercise for all children. Final variable-ratio rates were higher than those under fixed ratios found in previous research, with rates for 2 of the 3 obese boys approximating those of the nonobese.     

Varied intensities of training, predicted maximum oxygen uptake and the minimum threshold hypothesis

In this study, 24 sedentary first-year male university students aged 17 to 24 yr. were assigned to one of four groups. Three of the groups underwent a 6-wk. training program consisting of a 30-min. bicycle ergometer ride, three times per week. A fourth group acted as a control. The experimental groups trained at workload intensities corresponding to predetermined heart rates of 125, 140, and 155 bpm, respectively. Analysis of scores indicated that changes in aerobic capacity occurred only if the intensity of training exceeded a minimal level. Essentially, these results replicated data from other studies.     

Perceived exertion and the field-independence--dependence dimension

Perceived exertion responses were compared between field-independent and field-dependent perceivers at three cycle-ergometer pedalling rates. 50 male subjects were classified according to mode of field approach on the basis of their performance on an embedded-figures test. Power output was held constant at 840 kpm/min., while pedalling rate was randomly set at 40, 60, or 80 rpm. Significant differences between the field-independent and -dependent groups were not found at the three pedalling rates for any of the physiological variables or for over-all, legs and chest ratings of perceived exertion. The extent of differentiated psychological functioning did not account for individual differences in perceptual reactance during muscular exertion.     

Acute aerobic exercise and information processing: Modulation of executive control in a Random Number Generation task

The immediate and short-term aftereffects of a bout of aerobic exercise on young adults’ executive functions were assessed. Sixteen participants performed a Random Number Generation (RNG) task, which measured two aspects of executive function, before, during, and after ergometer cycling exercise. In a separate session, participants completed the same sequence of testing while seated on an ergometer without pedaling. Results suggest that aerobic exercise: (1) selectively influences RNG indices related to the ability to alternate ascending and descending runs throughout the entire exercise bout; (2) induces a shift to a less effortful number generation strategy, particularly during the first few minutes of the exercise; and (3) has no significant influence on RNG performance as soon as the exercise terminates. The strategic adjustments observed during the exercise are interpreted in the framework of Hockey’s [Hockey, G. R. J. (1997). Compensatory control in the regulation of human performance under stress and high workload: A cognitive-energetical framework. Biological Psychology, 45, 73-93.] compensatory control model and suggest that concurrent effortful processes induced by cycling exercise may draw upon available attention resources and influence executive processing.     

Arousal, changeover responses, and preference in concurrent schedules

Pigeons were trained on multiple schedules that provided concurrent reinforcement in each of two components. In Experiment 1, one component consisted of a variable-interval (VI) 40-s schedule presented with a VI 20-s schedule, and the other a VI 40-s schedule presented with a VI 80-s schedule. After extended training, probe tests measured preference between the stimuli associated with the two 40-s schedules. Probe tests replicated the results of Belke (1992) that showed preference for the 40-s schedule that had been paired with the 80-s schedule. In a second condition, the overall reinforcer rate provided by the two components was equated by adding a signaled VI schedule to the component with the lower reinforcer rate. Probe results were unchanged. In Experiment 2, pigeons were trained on alternating concurrent VI 30-s VI 60-s schedules. One schedule provided 2-s access to food and the other provided 6-s access. The larger reinforcer magnitude produced higher response rates and was preferred on probe trials. Rate of changeover responding, however, did not differ as a function of reinforcer magnitude. The present results demonstrate that preference on probe trials is not a simple reflection of the pattern of changeover behavior established during training.