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Biomedical subjects

J A Nicholas

Publications and source records attributed to J A Nicholas.

At least 55 records · Page 3Linked to original sources
PubMed1986

Using exercise respiratory measurements to compare methods of exercise prescription.

Exercise heart rate (HR) ranges based on peak HR, age-predicted maximal HR and peak oxygen consumption were compared to determine which method is most likely to result in an exercise prescription within guidelines determined from exercise respiratory measurements (upper limit--ventilatory threshold; lower limit--50% peak oxygen consumption). Exercise prescriptions based on either 80% peak HR or 70% peak measured oxygen consumption were significantly more likely to be within these guidelines (p less than 0.05) than other criteria tested; there was no significant difference between these 2 methods. Recommended exercise intensity based on 85% peak HR and 80% peak oxygen uptake resulted in a large percentage of patients with a heart rate above the ventilatory threshold (46% and 54%, respectively), whereas target HR derived from 75% peak HR and 60% peak oxygen consumption resulted in many patients with a heart rate below the lower limit (38% and 42%, respectively). Exercise prescription based on predicted maximal HR was of little value, regardless of the percentage used to determine target heart rate. The best methods identified in this study yielded an exercise intensity exceeding ventilatory threshold 15 to 20% of the time. Exercise prescription based on direct assessment of the ventilatory threshold is therefore preferred.

Adult↗
PubMed1986

Principles of exercise prescription for patients with coronary artery disease.

Exercise performance is determined by the interaction of many systems. Cardiac disease, non-cardiovascular pathology, physical training, and the hemodynamic response to the type of exercise the patient wants to perform should all be considered when developing an exercise prescription. There are two stages for deriving a complete exercise prescription, determination of optimal exercise intensity from an exercise test and adoption of the recommendation to include other forms of exercise. The recommendation is usually based on a target oxygen consumption or a target heart rate derived from a treadmill test, but both of these methods may be of limited effectiveness. Ventilatory measurements during exercise, which reflect metabolic changes, are a useful adjunct. The exercise prescription must be individualized to the patient's needs, and may have to be modified so that exercise intensity remains within acceptable limits.

Cardiac Output↗
PubMed1985

Orthopedic problems in athletes.

Physicians and patients must recognize the demands of the sport involved, as well as the individual's ability to meet those demands. Careful analysis of the sport and examination of the patient to assess recovery and chances of reinjury are mandatory, if he is to enjoy sports after injury. Physicians should become familiar with padding, shoes, warm-up programs, preparticipation examinations, and protective equipment and devices, all of which are helpful in preventing sports injuries. We have touched only briefly on the epidemic problem of quality of life trauma that is part of our society. Because injuries result in punishment to the soul as well as to the body of a person, the sports participant deserves a comprehensive, scientific, multidisciplinary approach in order to return to the state of physical and emotional well-being he enjoyed before the injury. For this reason a physician must examine each patient carefully and with regard for the individual's ability to be sure of the diagnosis for subsequent treatment.

Adolescent↗
PubMed1984

Plasma osmolality, volume, and renin activity at the "anaerobic threshold".

Plasma renin activity (PRA), volume (PV), osmolality, and hemodynamic parameters were examined in relation to the anaerobic threshold (AT) during progressive cycle ergometry (PE) and repetitive bouts of unilateral isokinetic knee extension-flexion (LE) at 50% maximum voluntary contractions in eight normotensive males. During PE, the observed rise in PRA paralleled that of lactate with abrupt increases occurring at the AT. Correlation of % delta lactate (La), % delta osmolality, and % delta PV with % delta PRA were r = 0.65, 0.36, and -0.51, respectively (all P less than 0.01). In addition, when mean arterial pressure was plotted as a function of VO2, the rate of rise was greater below the AT than above the AT (11.5 vs. -2.4 mmHg X l-1 X min, P less than 0.001). A time control study (TC) exercising subjects for the same duration but at work rates maintained below the AT resulted in significantly lower values for both PRA and La (7.18 vs. 11.27 mg angiotensin I (ANG I) X ml-1 X min and 3.16 vs. 9.93 mM, P less than 0.05 for TC vs. PE) while producing a similar fall in % delta PV and rise in osmolality. During LE, a high correlation was obtained for % delta PRA and % delta La (r = 0.86, P less than 0.01) but not for % delta PRA with % delta PV or % delta osmolality. The data demonstrate that PRA parallels lactate during exercise and that mean arterial pressure rises more slowly beyond the AT despite a more rapid rise in PRA.

Adult↗
PubMed1984

The value of sports profiling.

In his presidential presentation to the American Orthopedic Association in 1975, Inman said, "Man is a machine that moves . . . and expends energy." He was all too ahead of his time. Profiling, by recognizing that the body is a machine with links, studies the biophysical, biochemical, and biomechanical links of the body's systems. These studies, carried out on athletes and potential athletes of all ages, yield data with useful clinical and research applications. The continued use and study of profiling data will certainly enhance performance, increase enjoyment of athletes for years to come, and, we believe, prevent injury.

Humans↗
PubMed1983

Prescription information leaflets: a pilot study in general practice.

Leaflets containing information about medicines were issued to 56 patients prescribed penicillins and 43 patients prescribed non-steroidal anti-inflammatory drugs. The patients were interviewed between four and 10 days later and their responses compared with those of 65 patients prescribed penicillin and 33 prescribed nonsteroidal anti-inflammatory drugs who did not receive a leaflet. Patients who received a leaflet were more likely to be completely satisfied with their treatment and with the information they had been given. They were also more likely to know the name of their medicine and much more aware of potential unwanted effects. Although there was no evidence that knowledge increased the incidence of adverse effects, when these did occur they were more likely to be recognised as being due to the medicine. Further studies of other leaflets are warranted, including leaflets for drugs that are taken long term.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1982

Long-duration submaximal exercise conditioning in hemodialysis patients.

Objective changes in exercise tolerance were evaluated in five chronic hemodialysis patients (HD) following a ten week aerobic treadmill exercise conditioning program designed to exercise patients at a level approximating their anaerobic threshold (AT). This exercise conditioning program resulted in a 21% increase in peak oxygen consumption, an increase in test duration from 17.40 +/- 1.26 to 22.60 +/- 0.87 min (P less than 0.025), and an increase in AT from 0.81 +/- 0.08 to 0.97 +/- 0.08 1/min (P less than 0.05). These physiologic changes in exercise tolerance resulted in an overall increase in work capacity permitting the HD patient to perform a larger portion of the imposed work load aerobically.

Adult↗
PubMed1982

The nature of torque "overshoot" in Cybex isokinetic dynamometry.

Transient peaks or "spikes" frequently appear in the initial segments of torque curves recorded with the Cybex isokinetic dynamometer. The purpose of this investigation was to determine whether these spikes represent artifact or transient initial surges of true muscular force output. Cinematographic analysis using both inert weights and a human subject as the source of torque input to the Cybex revealed that the dynamometer's input lever initially exceeded the pre-set angular velocity by an amount ranging from 11% (inert weight; pre-set Cybex velocity = 180 degrees/s) to 200% (human hip abduction; pre-set velocity = 30 degrees/s). The majority of this "overspeeding" occurred in the latter part of the free acceleration period, prior to the engagement of the dynamometer's resistance mechanism. The remainder occurred in the initial part of the elastic loading phase, just after resistance had engaged. A sharp deceleration of the overspeeding lever and the affixed weight or limb then followed in response to the dynamometer's continuing build-up of resistance. Simultaneous with this deceleration, a prominent torque spike was recorded that superseded the correct (mechanical equilibrium) torque value. Within our error of measurement, the deceleration observed in the film quantitatively accounted for all of the "overshoot" torque, i.e., that amount of the spike that exceeded the correct value. It was concluded that such prominent, initial torque spikes represent inertial forces and should not be confused with true muscular tension development.

Biomechanical Phenomena↗
PubMed1981

Effect of physical training on exercise performance of children following surgical repair of congenital heart disease.

The effect of physical training on the exercise performance of 26 patients following surgical repair of tetralogy of Fallot (16 patients) and ventricular septal defect (ten patients) was evaluated. Base line exercise testing was performed on a bicycle ergometer using the technique of Godfrey. Patients were placed on a six-week alternate day submaximal interval home exercise program of varying duration and intensity. Work loads at 50%, 60%, and 70% maximum oxygen consumption were selected to maintain heart rates between 130 and 160 beats per minute. Subjects completed an average of 18 of the possible 21 training sessions (range 11 to 21). A 25% improvement (p less than .001) was noted in maximum work capacity (747 to 935 km). Sixty-five percent of the patients performed at less than expected maximum work capacity prior to training, but only 31% performed at less than expected maximum work capacity after training. Repeat testing at work loads of one-third, one-half, and two-thirds the original maximum work capacity revealed improved aerobic efficiency as manifested by significantly decreased oxygen consumption and heart rate at each level of work. No significant difference was noted in maximum oxygen consumption. It is concluded that physical training can improve the exercise performance of patients after surgical repair, permitting the individuals to function at levels of activity at, or closely approaching, normal.

Adolescent↗
PubMed1980

Pre-participation sports assessment--an objective evaluation.

The yield from a pre-participation sports examination consisting of a review of the medical history, routine physical examination, musculoskeletal examination, laboratory screening and an assessment of fitness by evaluation of body composition, flexibility, and muscular strength testing was studied. There were 701 students evaluated. Two students (0.3%) were excluded from participation because of medical problems and seven (1%) because of orthopedic problems. Sixty students (8.6%) were referred for additional medical evaluation. Thirty-five students (5.0%) required further orthopedic evaluation. All of the students who required additional evaluations were eventually granted permission to participate. The review of the medical history was positive in seven of the restricted students and 40 of the referred students. The routine physical examination was normal in the two restricted students and abnormal in 14 of the referred students. The musculoskeletal examination was abnormal in all of the students restricted or referred for orthopedic problems. The assessment of physical fitness revealed that 32% of the students had excessive body fat, 10% to 15% of both boys and girls had excessive muscle tightness in either the upper or lower body and approximately 5% of the students had weakness in hip abductors or flexors. Significant unilateral strength deficits were also found. When performed for the purpose of restricting participation or referring students for additional evaluation, the medical history and musculoskeletal examination are the components of the pre-participation sports examination with the highest yield. Additionally, the aspects of the examination which related to fitness revealed a significant number of abnormalities.

Adolescent↗
PubMed1979

Effect of exercise on lipid metabolism and dietary intake in hemodialysis patients.

In conclusion, a 10 wk exercise conditioning program in stable chronic hemodialysis patients resulted in improved exercise endurance without apparent adverse effects on nutritional status or lipid metabolism. Changes were observed suggesting a beneficial effect on carbohydrate and bone metabolism. The exercise-induced rise in serum creatinine may reflect an increase in muscle mass.

Adult↗
PubMed1978

Factors influencing manual muscle tests in physical therapy.

To determine whether it is the amount or the duration of the force applied manually by the tester, or both, that determines the tester's perception of the strength of the hip flexor or abductor muscles, an electromechanical device was designed which was placed between the tester's hand and the subject's limb. With the device we measured the force applied to the limb, the time interval during which it was applied, and the angular position of the limb during the entire test. In 240 such tests, the testers' ratings of the differences in strength between the right and left sides were correlated with seven variables involving force and time. It was found statistically that the impluse--that is, the duration of the tester's effort multiplied by the average applied force during each test--was the factor that most influenced the tester in the ratings.

Adolescent↗