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Understanding cardiac responses to exercise in healthy subjects is important in the evaluation of youth with heart disease. This review article incorporates previously published original research from the authors’ laboratory to examine changes in stroke volume during progressive exercise which are consistent with a model in which circulatory responses are controlled by alterations in the systemic vascular resistance. Stroke volume dynamics and cardiovascular responses to a progressive upright cycle test were examined in three groups of healthy, untrained adolescent subjects. These indicated a) a progressive decease in systemic vascular resistance, b) little change in stroke volume after an initial rise related to orthostatic changes in ventricular refilling, c) evidence of a constant or slightly declining left ventricular end diastolic filling pressure, d) and increases in markers of ventricular contractility. These observations are consistent with peripheral (vascular resistance) rather than central (cardiac) control of circulation with exercise. Changes in stroke volume during exercise need to be interpreted in respect to alterations in heart rate and myocardial functional capacity.

A treatment and rehabilitation protocol was implemented on a university football player sustaining a second-degree lateral ankle sprain. The initial treatment plan involved the application of the RICE principle (rest, ice, compression, and elevation). This particular rehabilitation protocol was aimed at restoring range of motion and function at the earliest possible time with the use of a cryokinetic technique developed by Knight and with progressive exercise. The subject in this case study returned to full participation 6 days postinjury. The results from this report indicate that a program of cryokinetics and functional progressive exercise performed within pain-free limits can greatly enhance the return of an athlete to competition.

The effect of oral creatine supplementation on aerobic and anaerobic performance was investigated in 16 elite male rowers during 7-day endurance training. Before and after the daily ingestion of 20 g creatine monohydrate for 5 days (Cr-Group, n = 8) or placebo (Pl-Group, n = 8), subjects performed two exercise tests on a rowing ergometer: (a) incremental exercise consisting of 3-min stage durations and increased by 50 W until volitional exhaustion; (b) an all-out anaerobic exercise performed against a constant load of 7 W/kg. Heart rate and blood lactate concentrations were determined during exercise and recovery. Maximal power output did not significantly differ after the treatment in either group. The mean individual lactate threshold rose significantly after Cr treatment from 314.3 ± 5.0 W to 335.6 ± 7.1 W (p < .01), as compared with 305.0 ± 6.9 W and 308.9 ± 5.9 W (ns), before and after placebo ingestion, respectively. During the anaerobic test, the athletes supplemented with creatine were able to continue rowing longer (mean increase, 12.1 ± 4.5 s; p < .01) than Pl-Group (2.4 ± 8.2 s; ns). No significant differences were found between groups in blood LA after the all-out exercise. The results indicate that in elite rowers, creatine supplementation improves endurance (expressed by the individual lactate threshold) and anaerobic performance, independent of the effect of intensive endurance training.

Nine male elite wheelchair athletes performed a continuous progressive exercise test on a wheelchair ergometer to determine peak oxygen uptake. Three were paraplegic distance track competitors (SCI–TR), three were amputee distance track athletes (AMP–TR), and three were paraplegic basketball players (SCI–BB). Analysis of variance indicated a significant difference in the relative peak oxygen uptake between the groups, with the SCI–TR and AMP–TR groups having higher values than the SCI–BB group. No group differences were found in age, mass, oxygen uptake, ventilation, heart rate, ventilatory equivalent for oxygen, and oxygen pulse at maximal exercise. The absence of the mass of the lower extremities in the AMP–TR group has a significant effect on peak oxygen uptake relative to body mass, and relative peak oxygen uptake differences between individual SCI–TR and AMP–TR athletes did not appear to reflect performance differences in actual distance track events.

The effects of 12 wk of exercise training using weighted vests on bone turnover and isokinetic strength were evaluated in postmenopausal women randomly assigned as exercisers (EX; n = 9) or controls (CON; n = 7). Training included 3 multimodal exercise sessions per wk wearing weighted vests. The vest load was progressively increased each wk to a maximum of 15% of body weight. Bone turnover was determined from resting levels of serum osteocalcin and NTx. Knee and ankle strength were measured at 60°/s and 180°/s using an isokinetic dynamometer. After 12 wk, NTx decreased by 14.5% (P ≤ .05) in EX, with no significant changes in osteocalcin. EX also showed a 40% (P ≤ .05) improvement in ankle plantar-flexion strength at 60°/s. Relative body fat significantly decreased and fat-free mass increased in EX. Exercise compliance was 80%. These findings support the use of progressive exercise training using weighted vests in postmenopausal women.

The present study evaluated the effects of a reinforcement based aerobic and resistance exercise program on three obese men with mental retardation and below average fitness levels. A multiple-baseline-across-subjects design was employed to evaluate treatment effectiveness and retention of treatment effects on five dependent measures: body weight, percent body fat (body composition), oxygen consumption (predicted max V̇O₂ in ml/kg/min), composite isometric strength (in kg of force), and work productivity (pieces of work completed). Subjects improved during treatment from their baseline scores on cardiovascular fitness, strength, and work productivity measurements (p<.05); however, retention of gains made during treatment were inconsistent and the data that indicated subjects’ scores were regressing back toward baseline measurements. There were no significant differences for body weight and percent body fat measurements for treatment and retention phases (p>.05). Results indicated that adults with mental retardation respond to a progressive exercise program in much the same manner as their nonretarded peers and that such an exercise program can facilitate job performance.

The article describes the design and preliminary evaluation of a 17-week, twice-weekly, comprehensive, progressive exercise program for frail elderly adults. The main objective was to maintain or improve mobility and performance of daily activities essential for independent functioning. Strength, speed, endurance, flexibility, and coordination were trained by walking, kneeling, and chair stands, performed in the context of motor behavior such as games and daily activities. The acceptability of the exercise program was evaluated in a population of community-dwelling, frail older adults (mean age 77.6 ± 5.4 years). Eighty-one percent completed the program. Program appreciation and attendance were high. Seventy-three percent reported wanting to continue participating if possible—although most only once a week. At follow-up (1–1.5 years afterward) 30% were still participating in an exercise program. The exercise program was enjoyed and accepted by a population of frail, previously sedentary elderly adults. Widespread implementation of this program could increase physical activity among frail older adults.

Clinical exercise physiologists and physicians administering stress tests in the young have used oxygen pulse as a surrogate measure of stroke volume. It is important to recognize 1) the accuracy of O₂ pulse in predicting maximal stroke volume during exercise, and 2) the normal pattern of O₂ pulse during a progressive exercise test. This study examined both of these issues in a cohort of 44 healthy adolescent males and females (ages 14–16 years) who performed routine progressive cycle exercise to exhaustion. Gas exchange variables were measured by standard open circuit techniques. Stroke volume at rest and during exercise was assessed by the Doppler ultrasound method. At peak exercise O₂ pulse correlated closely with stroke volume (r = .73) with a SEE of 12.6 ml·beat^-1. Values of maximal O₂ pulse in nonathletic boys and girls were 13.3 ± 2.5 and 11.0 ± 1.7 ml·beat^-1, respectively. After the initial workload, a steady rise was observed in O₂ pulse, entirely reflecting an increasing arterial venous oxygen difference, with a slope of approximately 4 ml/beat per 100 watts work load. The findings support the use of O₂ pulse as a valid predictor of stroke volume during exercise in youth with a moderately high level of accuracy.

Purpose: The oxygen uptake efficiency slope (OUES) has been proposed as an ‘effort-independent’ measure of cardiopulmonary exercise capacity, which could be used as an alternative measurement for peak oxygen uptake (VO_2peak) in populations unable or unwilling to perform maximal exercise. The aim of the current study was to investigate the validity of the OUES in children with cystic fibrosis (CF). Methods: Exercise data of 22 children with CF and mild to moderate airflow obstruction were analyzed and compared with exercise data of 22 healthy children. The OUES was calculated using data up to three different relative exercise intensities, namely 50%, 75%, and 100% of the total exercise duration, and normalized for body surface area (BSA). Results: Only the OUES/BSA using the first 50% of the total exercise duration was significantly different between the groups. OUES/BSA values determined at different exercise intensities differed significantly within patients with CF and correlated only moderately with VO_2peak and the ventilatory threshold. Conclusion: The OUES is not a valid submaximal measure of cardiopulmonary exercise capacity in children with mild to moderate CF, due to its limited distinguishing properties, its nonlinearity throughout progressive exercise, and its moderate correlation with VO_2peak and the ventilatory threshold.