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PubMed2005

The diagnostic value of intracompartmental pressure measurement, magnetic resonance imaging, and near-infrared spectroscopy in chronic exertional compartment syndrome: a prospective study in 50 patients.

BACKGROUND: Patients with chronic exertional compartment syndrome have pain during exercise that usually subsides at rest. History and physical examination may raise suspicion of the syndrome; diagnosis is usually confirmed with intracompartmental pressure measurement after exercise. Studies have shown that magnetic resonance imaging and near-infrared spectroscopy have diagnostic ability in this syndrome. HYPOTHESIS: Magnetic resonance imaging and near-infrared spectroscopy can be used to diagnose chronic exertional compartment syndrome. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 2. METHODS: Patients were enrolled if there was clinical suspicion of chronic exertional compartment syndrome, and a fasciotomy was performed based on this suspicion. Before fasciotomy, intracompartmental pressure, near-infrared spectroscopy, and magnetic resonance imaging data were collected during and after exercise on a treadmill. Near-infrared spectroscopy and intracompartmental pressure values were recorded in the same manner after fasciotomy. Retrospective proof that diagnosis of the syndrome had been correct was the absence of exertional complaints from the preoperative examination during exercise at postfasciotomy visit. RESULTS: Fifty patients (100 legs) participated in the prefasciotomy visit; 3 refused fasciotomy; 2 were lost to follow-up. Of 45 patients who completed the postfasciotomy visit, the diagnosis of chronic exertional compartment syndrome was retrospectively confirmed in 42 patients and discarded in 3 patients. The sensitivity for intracompartmental pressure (cutoff point, 35 mmHg) found in this study was 77% (67%-86%, exact 95% confidence interval), lower than estimates from the literature (93%). The sensitivity (previously defined cutoff) for near-infrared spectroscopy was 85% (76%-92%, exact 95% confidence interval), validating the estimate found in the literature (85%). Sensitivity of magnetic resonance imaging was comparable to that of intracompartmental pressure and near-infrared spectroscopy; associated specificity at a given sensitivity appeared to be lower with magnetic resonance imaging. CONCLUSION: This study validates the sensitivity of near-infrared spectroscopy and provides estimates for the sensitivity and specificity of magnetic resonance imaging in chronic exertional compartment syndrome in a large group of patients. The sensitivity of noninvasive near-infrared spectroscopy is clinically equivalent to that of invasive intracompartmental pressure measurements.

Adolescent↗
PubMed2001

Identification of risk factors for exertional heat-related illnesses in long-distance cyclists: experience from the California AIDS Ride.

OBJECTIVES: To identify risk factors for exertional heat-related illnesses and to determine if patients who are afflicted with the human immunodeficiency virus or have acquired immunodeficiency syndrome have an increased risk of exertional heat-related illness. DESIGN: Descriptive, retrospective, matched case-control study. SETTING: Mobile community of 2,650 participants in the California AIDS Ride 3. PARTICIPANTS: Participants included 117 patients presenting for medical care with heat-related illnesses and 234 age-, gender-, and registration site-matched control subjects who did not develop a heat-related illness. METHODS: Retrospective, matched case-control study utilizing univariate and multivariate conditional logistic regression to determine if human immunodeficiency virus seropositivity, the number of chronic medical illnesses, or the number of current medications known to affect heat dissipation increased the risk of exertional heat-related illnesses. RESULTS: The multivariate model revealed that patients with a greater number of chronic medical illnesses were at a significantly increased risk of a heat-related illness (odds ratio = 1.6, 95% CI = 1.2-2.1). The number of current medications (odds ratio = 1.1, 95% CI = 0.8-1.5) and human immunodeficiency virus seropositivity (odds ratio = 0.7, 95% CI = 0.2-3.1) were not significant predictors of risk for exertional heat-related illness. CONCLUSIONS: Those riders suffering from a greater number of chronic medical illnesses were at a greater risk for developing an exertional heat-related illness. Human immunodeficiency virus seropositivity alone was not associated with increased risk of exertional heat-related illness.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Dietary control of exertional rhabdomyolysis in horses.

OBJECTIVE: To determine whether feeding a low-carbohydrate, high-fat diet would decrease severity of exercise-induced muscle injury in horses with exertional rhabdomyolysis. ANIMALS: 19 horses with a history of exertional rhabdomyolysis. DESIGN: Case series. PROCEDURE: Specimens of the semitendinosus or semimembranosus muscle were obtained for histologic examination, and serum creatine kinase (CK) and aspartate transaminase (AST) activities 4 hours after exercise were determined. Horses were then fed a low-carbohydrate, high-fat diet, and serum CK and AST activities 4 hours after exercise were reevaluated at approximately monthly intervals for 3 to 6 months. RESULTS: Serum CK and AST activities 4 hours after exercise were high before any change in diet. All 19 horses had evidence of chronic myopathic change and abnormal glycogen accumulation in muscle biopsy specimens; 11 horses also had evidence of complex polysaccharide accumulation. Adaptation to diet change required approximately 3 to 6 months. Sixteen horses did not have any episodes of exertional rhabdomyolysis after 3 to 6 months of diet change, and 3 horses had mild episodes of exertional rhabdomyolysis following either a reduction in dietary fat intake or restriction in exercise. Postexercise serum CK and AST activities 3 to 6 months after the change in diet were significantly less than initial values. CLINICAL IMPLICATIONS: Results indicated that exertional rhabdomyolysis may be a result of abnormal carbohydrate metabolism in some horses. Feeding a diet with low carbohydrate and high fat content may reduce severity of exercise-induced injury in some horses with exertional rhabdomyolysis.

Animal Feed↗
PubMed1999

Exertional leg symptoms other than intermittent claudication are common in peripheral arterial disease.

BACKGROUND: Epidemiological data show that most community-dwelling men and women with lower-extremity peripheral arterial disease (PAD) do not have typical symptoms of intermittent claudication. We compared the prevalence of intermittent claudication, leg symptoms other than intermittent claudication, and absence of exertional leg symptoms between patients with PAD identified from a blood flow laboratory (group 1), patients with PAD in a general medicine practice (group 2), and control patients without PAD (group 3). METHODS: Numbers of participants in groups 1, 2, and 3 were 137, 26, and 105, respectively. Patients with previously diagnosed PAD were excluded from groups 2 and 3. All participants underwent ankle-brachial index measurement and were administered the San Diego claudication questionnaire to assess leg symptoms. RESULTS: Within groups 1, 2, and 3, prevalences of intermittent claudication were 28.5% (n = 39), 3.8% (n = 1), and 3.8% (n= 4), respectively. Prevalences of exertional leg symptoms other than intermittent claudication were 56.2% (n= 77), 42.3% (n= 11), and 19.0% (n = 20), respectively. Absence of exertional leg symptoms was reported by 15.3% (n= 21), 53.8% (n= 14), and 77.1% (n=81), respectively. Among patients with PAD, older age, male sex, diabetes mellitus, and group 2 vs group 1 status were associated independently with absence of exertional leg symptoms in multivariable regression analysis. Lower ankle-brachial index levels and group 1 vs group 2 status were associated with intermittent claudication. CONCLUSIONS: Clinical manifestations of PAD are diverse, particularly among patients identified by ankle-brachial index screening. Exertional leg symptoms other than intermittent claudication are common in PAD. Patients with PAD who are older, male, diabetic, or identified with ankle-brachial index screening in a primary care setting are more likely to have asymptomatic PAD.

Age Factors↗
PubMed1988

Benefits of short-term muscular training in reducing the effects of muscular over-exertion.

Muscle soreness, serum creatine kinase (CK), and serum and urinary hydroxyproline levels were examined following muscle over-exertion and resistance training. Seven untrained men performed high intensity leg-extension exercises at a resistance at which they could initially accomplish 90% of their 10 repetitions maximum (10 RM), for 30 minutes to induce muscle over-exertion. In Phase 1 a single bout of muscular over-exertion was followed by a week of rest. Phase 2, the training period, was a repeat of the over-exertion workload of Phase 1 for five consecutive days. Phase 3 was a single bout of over-exertion at a higher 10 RM workload. Normo-responsive and hyper-responsive changes in serum CK were exhibited by different subjects in Phase 1. Muscle soreness was perceived by both groups but to a greater extent in the hyper-responsive group. Serum CK and muscle soreness values were lower during Phase 2 and 3 than in Phase 1. Neither serum nor urinary hydroxyproline levels changed significantly post-exercise. These findings show that a single bout of intense exercise and a brief period of muscular training reduces serum CK and muscle soreness responses following a subsequent single bout of exercise at a higher intensity.

Adult↗
PubMed2003

Perceived exertion is elevated in old age during an isometric fatigue task.

The purposes of this study were to compare the ratings of perceived exertion (RPE) of young [25 (1) years] and old men [84 (1) years] during intermittent (3 s on, 2 s off) voluntary isometric contractions of the elbow flexors at 60% of each subject's maximal voluntary contraction (MVC) force, and to determine whether potential differences in RPE were accompanied by altered neuromuscular parameters during fatigue. Subjects performed the fatigue protocol on two different visits. All subjects in both groups reported a maximal (10) perceived exertion using a modified Borg-scale at fatigue, but the old men reported a greater perceived exertion compared to the young men at an initial stage of the protocol during the two visits (P<0.05). The amount of prefatigue MVC force remaining at fatigue was not different between groups (approximately 57%), and voluntary activation, as assessed with twitch interpolation, was not different from the prefatigue value for either group throughout the fatigue protocol (>95%), and did not show any age-related difference. Moreover, there was no significant difference in 60% target electromyography between groups at any time point during the fatigue protocol, and there was no significant effect of age on the decline in 50-Hz tetanic force. Thus, the old men were able to exert themselves to the same relative degree of muscle fatigue as the young men, and despite an elevated perceived exertion compared to the young men during initial stages of the protocol, they did not terminate the protocol prematurely, or demonstrate an inability to sustain a high level of voluntary activation.

Adult↗
PubMed1983

Prognostic and predictive value of exertional hypotension in suspected coronary heart disease.

The prognostic and predictive value of exertional hypotension was assessed in 1,241 patients having treadmill maximal exercise testing, coronary arteriography, and follow-up averaging 5.4 years. Medically treated patients with coronary artery disease (CAD) with exertional hypotension had poorer survival than did those without such hypotension; however, maximum systolic pressure during exercise was a more powerful predictor of survival. Patients with exertional hypotension had more extensive CAD and more left ventricular (LV) dysfunction than did patients who had an increase in blood pressure with exertion; these findings probably account for the impaired survival. However, exertional hypotension, was an insensitive indicator of significant left main coronary artery stenosis, 3-vessel disease, or severe resting LV dysfunction.

Adult↗
PubMed1985

Different susceptibility to myocardial ischemia provoked by hyperventilation and cold pressor test in exertional and variant angina pectoris.

Coronary constriction at the site of atherosclerotic stenoses has been suggested to play an important role in modulating the frequency of symptoms in patients with exertional angina. To investigate whether stimuli triggering coronary constriction have similar effects in patients with exertional and variant angina, responses to hyperventilation (HV) and cold pressor test (CPT) were evaluated. Twenty patients with chronic exertional angina, positive exercise test results and coronary heart disease were compared with 14 patients with variant angina and ST-segment elevation during an ergonovine test. In patients with exertional angina, the CPT produced diagnostic ST-segment depression in 6 of 20 patients (30%) at levels of rate-pressure product much lower than those during the exercise test; all patients had low effort tolerance and severe coronary artery disease. HV produced diagnostic ST-segment depression in only 1 of 20 patients (5%) (p less than 0.05 compared to that with CPT). Conversely, in patients with variant angina, HV produced ST-segment elevation in 11 of 14 patients (78%) and CPT produced elevation in only 2 of 14 (14%) (p less than 0.01). Thus, coronary constriction can provoke myocardial ischemia not only in patients with variant angina but also in some patients with exertional angina. Furthermore, the 2 groups of patients have a different susceptibility to stimuli known to produce coronary constriction.

Adult↗
PubMed2005

The impact of specific exertion on the efficiency and ease of the voice: a pilot study.

Even though most singers and other professional voice users are encouraged to relax to optimize the quality and performance of the voice, observations of acclaimed singers, actors, and public speakers would suggest otherwise. These successful vocal performers appear to be energized, actively working and exerting themselves. For this reason, a study was designed to explore the role of exertion in maintaining and optimizing the voice. The focus of this study was the possibility that increasing exertion could improve the voice and might result in the voice user experiencing less strain and, therefore, more comfort and ease. Ten subjects were recorded before and after completing a workshop to develop their skills with precise use of effort involving selected parameters of the larynx and vocal tract. Self-reported ratings of degree of exertion and level of comfort were collected at the time of each recording. The preworkshop and postworkshop recordings were analyzed acoustically and perceptually to compare the degree of noise in the signal that corresponds with the efficiency of the voice. The results indicated that, for all subjects, the quality of the voice improved with an increase in the use of specific exertion. Furthermore, ease and comfort also significantly increased.

Adolescent↗
PubMed1996

Differential responses in left ventricular diastolic filling dynamics with isometric handgrip versus isotonic treadmill exertion.

Although the hemodynamic responses to isotonic and isometric exercise are different, few data exist comparing the response to left ventricular (LV) diastolic filling dynamics with these two forms of exertion. Therefore we performed Doppler examination before and at the end of isotonic and isometric exercise in 20 normal volunteers to define the differential responses of LV filling to these two forms of exertion. Transmitral inflow velocity signals from the apical view and phonocardiography were recorded before and at the termination of treadmill exercise (TRD) to 11 METs and handgrip (HG) 50% maximal for 2 minutes). Mean blood pressure (mBP), heart rate (HR), early diastolic (E) and late atrial (A) inflow velocities, mean acceleration rate (ACC) of E wave, time velocity integral of inflow (Ti), and isovolumic relaxation time (IRT) from second heart sound to onset mitral inflow were measured. Absolute changes from baseline were significantly different for the two forms of exertion: TRD versus HG: BP = 11 +/- 9 versus 36 +/- 10 mm Hg, HR = 37 +/- 16 versus 16 +/- 9 beats/min, E = 11.6 +/- 11.3 versus -7.0 +/- 9.4 cm/sec, A = 29.9 +/- 14.5 versus 14 +/- 12 cm/sec, ACC = 164 +/- 151 versus -56 +/- 135 cm/sec2, Ti = 1.9 +/- 3.0 versus -1.7 +/- 1.7 cm, and IRT = -12 +/- 9 versus 9 +/- 10 msec, all p < 0.0001 except for A, p < 0.001). Isotonic treadmill exercise resulted in enhanced early diastolic filling manifested by increases in E and ACC and a decreased in IRT. Conversely, isometric handgrip exercise produced evidence of reduced early filling including decreased E and ACC and slightly increased IRT. Thus the response of LV filling dynamics recorded by Doppler differs for isotonic and isometric exertion and likely reflects the variable pressure and flow alterations induced by these two forms of exertion.

Adult↗
PubMed2000

Self-perceived exertion level and objective evaluation of neuromuscular fatigue in a training session of orchestral violin players.

The aim of the study was to investigate the self-perceived exertion level and an objective measurement of muscle fatigue on violin players before and after a training session. Fourteen professional violin players volunteered in this study. Surveillance study was used to investigate the demographic characteristics, instrument playing background, playing habits variables and factors associated with playing-related musculoskeletal complaints (PRMCs). The subjective rating of the training-induced exertion was evaluated by the Borg scale ratings of perceived exertion (RPE). Surface electromyography (EMG) was used to record the fatigue level of the upper trapezius muscles before and after a training session. Medium frequency (MF) of the EMG signals was used to document the fatigue rate of this muscle. Descriptive statistics revealed a 79% prevalence rate of PRMCs with neck and shoulder region accounting for 57.1% of the areas reported. On the self-perceived exertion level associated with the training session, results indicated a significant increase in fatigue level (p = 0.003) after the training session. Regression analysis and paired samples t-tests revealed no significant difference in the slopes of MF on both sides of trapezius muscle, before and after the training sessions. The disparity in the subjective perception with the objective findings indicated that the violinists' self-perceived exertion arises from multiple sources. The high prevalence of PRMCs in this profession warrants further ergonomic investigation of possible work-related risk factors.

Adult↗
PubMed1999

Relationship between exertional symptoms and functional capacity in patients with heart failure.

OBJECTIVES: The present study was undertaken to investigate the relationship over time between exertional symptoms in heart failure and functional capacity. BACKGROUND: Most clinicians rely on exertional symptoms rather than on exercise testing to assess functional capacity in heart failure. However, it remains uncertain whether the subjective symptoms reported by patients provide a reliable index of functional capacity. METHODS: Fifty patients with heart failure underwent serial cardiopulmonary exercise testing and evaluation of exertional fatigue and dyspnea over a period of one to four years. Exercise testing was performed using the Naughton treadmill protocol and a MedGraphics metabolic cart. Fatigue and dyspnea were each scored from 0 to 3 (p = none, 1 = mild, 2 = moderate, 3 = severe). A composite symptom score was determined by adding together the fatigue and dyspnea scores. RESULTS: Patients underwent a total of 185 tests at an average interval of 4.3 months (average tests/patient = 3.7). Composite symptom scores noted at the time of exercise testing correlated significantly with peak exercise minute oxygen consumption (VO2) (r = 0.47, p < 0.01). In addition, the change in symptoms scores and change in peak VO2 noted between the baseline and final exercise test correlated significantly (r = 0.50, p < 0.01). However, patients reported few or no symptoms (symptom score < or =2) 45% of the time when peak VO2 was <14 ml/min/kg, consistent with a severe functional disability, and 72% of the time when peak VO2 was 14 to 18 ml/min/kg, consistent with moderate functional disability. CONCLUSIONS: Exertional symptoms reported by patients with heart failure generally correlate with maximal exercise capacity. However, exertional symptoms frequently underestimate the severity of functional disability. Cardiopulmonary exercise testing rather than symptoms should be used to assess functional capacity in heart failure.

Adult↗
PubMedDate not supplied

Spine loading in patients with low back pain during asymmetric lifting exertions.

BACKGROUND CONTEXT: Recurrent low back pain (LBP) is a common and costly problem that might be related to increased spine loads in those with LBP. However, we know little about how the spine is loaded when those with LBP perform lifting exertions. PURPOSE: Document spine loading patterns of patients with LBP performing symmetric and asymmetric lifting exertions compared with asymptomatic individuals performing the same tasks. STUDY DESIGN: Spine loadings during lifting exertions that varied in asymmetric origin as well as horizontal and vertical distance from the spine were compared between asymptomatic subjects and patients with LBP. METHODS: Sixty-two patients with LBP and 61 asymptomatic individuals performed a variety of lifting exertions that varied in lift origin horizontal and vertical position (region), lift asymmetry position and weight lifted. An electromyography-assisted model was used to evaluate spine loading in each subject during the lifting exertions. Differences in spine loading between the LBP and asymptomatic subjects were noted as a function of the experimental variables. RESULTS: Patients with LBP experienced greater spine compression and shear forces when performing lifting tasks compared with asymptomatic individuals. The least taxing conditions resulted in some of the greatest differences between LBP and asymptomatic individuals. CONCLUSIONS: Greater levels of antagonistic muscle coactivation resulted in increases in spine loading for patients with LBP. Specific lifting conditions that tend to exacerbate loading can be identified by means of physical workplace requirements. These findings may impact acceptable return-to-work conditions for those with LBP.

Adult↗
PubMed2002

Are nurses able to assess fatigue, exertion fatigue and types of fatigue in residential home patients?

Are nurses able to assess fatigue, exertion fatigue and types of fatigue in residential home patients? Although fatigue is recognized as a subjective, generalized, extensive and disabling health care problem with a relatively high prevalence among the chronically ill, there have been no studies to show whether nurses caring for fatigued subjects are able to accurately assess the level of fatigue that exists in these patients. The aim of the present study is to investigate this issue. The following research questions are formulated: (1) To what degree do the assessments of fatigue and exertion fatigue given by nurses and patients agree? and (2) To what degree do the assessments of types of fatigue given by nurses and patients agree? The method adopted employed a correlational design approach applied to residential home patients and nurses. Data were gathered by questionnaire. Data collected from 44 selected patients and two assessors (nurses) for each patient are used in the analyses. Measurement instruments used are the Dutch fatigue scale (DUFS), the Dutch exertion fatigue scale (DEFS), types of fatigue and sociodemographic variables. Measurement correlations between the patients and the nurses, both for the DUFS and DEFS, showed fair agreement (fatigue and exertion fatigue) and slight agreement (types of fatigue). The main conclusion of this study is that nurses working in residential home care are unable, in comparison with the patients themselves, to accurately assess patient's fatigue (fair agreement), exertion fatigue (fair agreement) and types of fatigue (slight agreement).

Aged↗
PubMed1993

Perceived exertion and discomfort associated with driving screws at various work locations and at different work frequencies.

Eighteen subjects drove screws with air-powered tools into perforated sheet metal at three vertical and two horizontal work locations using three different work paces (8, 10, and 12 screws/min). Subjects drove screws with a pistol-shaped tool on the vertical orientation at knee, elbow, and shoulder height. They used an in-line tool to drive screws on the horizontal surface. A horizontal beam was placed just below each subject's elbow height and they drove screws into it with the lower arm perpendicular to the torso and with the arms fully extended. Subjects drove screws for 10 min at each work location and frequency combination before they assessed the condition using the Borg ten-point ratio rating scale. Subjects also ranked seven body areas according to discomfort for each work location. A two-factor ANOVA (and comparable non-parametric statistics) showed that both work location and frequency were significant factors in determining the Borg ratings. As work pace increased, so did the Borg ratings of perceived exertion for each work location. For each incremental increase in work pace, the Borg ratings of perceived exertion increased 12% to 25%, depending on the work location. Driving screws at elbow height on the vertical surface and with the lower arm close to the body on the horizontal surface were the work locations with the smallest ratings of perceived exertion. The ratings of perceived exertion for driving screws at elbow height on the vertical surface were 18% to 50% lower than the ratings for driving screws at knee or shoulder height and the ratings of perceived exertion for driving screws with the lower arm close to the body on the horizontal surface were 21% to 24% lower than driving screws with the arms fully extended. No significant difference was found among the discomfort ranks given to the various body parts for the two horizontal work locations. Differences were found among the body part discomfort rankings for the vertical work locations. While driving screws at knee height, the torso was most stressed; the wrist and hand were most stressed while driving screws at elbow height, and the shoulder and upper arm were the body parts that were stressed the most while driving screws at shoulder height.

Adult↗
PubMed2003

The effects of acute stretching on hamstring muscle fatigue and perceived exertion.

The aim of this study was to examine the effects of an acute stretching regime on hamstring muscle fatigue and rating of perceived exertion during a dynamic, sub-maximal bout of resistance exercise. Sixteen healthy males (age 25.7 +/- 4.3 years, height 1.81 +/- 0.06 m, body mass 87.5 +/- 15.1 kg; mean +/- s) and 16 healthy females (age 24.9 +/- 4.5 years, height 1.67 +/- 0.06 m, body mass 62.9 +/- 9.4 kg) volunteered to participate in two experimental sessions. After establishing their one-repetition maximum for the hamstring curl, the participants were assigned at random to one of two groups. Group 1 performed three bouts of 20 s hamstring stretches with the assistance of one of the investigators, while group 2 did not perform the stretches; instead, they sat resting for 3 min. Then, after stretching or resting, the participants performed as many hamstring curls as they could at 60% of their one-repetition maximum established earlier. All participants were assessed for their perceived exertion using a modified Borg category ratio (CR-10) scale. The participants returned within 1 week to complete the experiment. This time group 1 did not perform hamstring stretches, whereas group 2 did. As on the first occasion, all participants performed hamstring curls after stretching or resting. The participants in group 1 were able to perform more curls on the second day of testing than their counterparts in group 2. There were no significant differences between males and females or between the stretch and non-stretch conditions. There was a significantly higher first repetition rating of perceived exertion for the stretch condition (2.88 +/- 1.01) than for the non-stretch condition (2.50 +/- 0.95); there was no significant difference in the median ratings of perceived exertion between the stretch and non-stretch conditions. Significantly higher power function exponents were exhibited in the non-stretch (0.57 +/- 0.16) than in the stretch condition (0.51 +/- 0.12). In addition, females exhibited significantly higher power function exponents than males, irrespective of stretch condition and day (females: 0.59 +/- 0.12; males: 0.49 +/- 0.11). In conclusion, we found a small but statistically significant effect of an acute bout of stretching on ratings of perceived exertion during fatiguing hamstring muscle resistance exercise.

Adult↗
PubMed1999

Physiological responses and perceptions of exertion in a step aerobics session.

The aims of this study were to establish the cardiovascular and metabolic demands of a university step aerobics session entitled 'Uni-Step' performed at three step heights, and to evaluate the use of heart rate and ratings of perceived exertion for the estimation of exercise intensity during this mode. Ten female participants in step aerobics (mean VO2max = 47.7, s = 6.8 ml.kg-1.min-1) performed a 40-min Uni-Step routine on steps of height 6, 8 and 10 inches (15.2, 20.3 and 25.4 cm). Oxygen uptake, heart rate and ratings of perceived exertion were recorded throughout each test. Maximum oxygen uptake (VO2max) and maximum heart rate were measured using a continuous treadmill protocol. The mean intensities were 45.6%, 51.6% and 56.2% VO2max for the 6-, 8- and 10-inch steps respectively. The mean percent heart rate reserves were 57.2%, 63.6% and 70.1% at these three heights respectively. Correlations indicated a weak relationship between %VO2max and ratings of perceived exertion for the 6- and 8-inch steps (r = 0.61 and 0.66 respectively) but a stronger one for the 10-inch step (r = 0.79). Uni-Step performed on the two highest steps was of a sufficient relative intensity to improve or maintain the cardiovascular fitness of participants in this study. The lowest step may be useful for participants of lower fitness. Heart rate overestimated the metabolic cost of Uni-Step at all three step heights and therefore caution is advised if used to predict intensity. Low correlations between %VO2max and ratings of perceived exertion at the two lower step heights indicate that ratings of perceived exertion may have limited utility in prescribing training intensity.

Adult↗
PubMed2002

Exerted effort and performance in climbing among boys: the influence of achievement goals, perceived ability, and task difficulty.

In achievement contexts such as sport, achievement goal theory assumes that an individual's major concern is to demonstrate competence. However, competence may be expressed in two ways: as task and ego involvement (Nicholls, 1989). Seventy-eight boys (M age = 13.6 years) performed five climbing courses, and the influence of achievement goals, perceived ability, and task difficulty on effort and performance was studied. According to the achievement goal theory: (a) task-involved boys exerted more effort and performed better than ego-involved boys; and (b) exerted effort was determined by an interaction of one's achievement goal, perceived ability (PA), and task difficulty. Ego-high PA boys and task-low PA boys exerted the most effort on the moderate course; ego-low PA boys exerted least effort on the moderate and very difficult courses. Finally, task-high PA boys exerted more effort on the most difficult courses. The motivational processes underlying these findings are discussed.

Adolescent↗