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Biomedical subjects

M H Cox

Publications and source records attributed to M H Cox.

8 recordsLinked to original sources
PubMed1992

Reliability and validity of a fitness assessment for epidemiological studies.

A pilot study was conducted to investigate the applicability of the Canadian Aerobic Fitness Test (CAFT) for use in epidemiological studies. Thirty subjects ranging in age from 18 to 65 were evaluated for cardiorespiratory fitness on four separate visits. Protocols used included maximal treadmill testing, maximal step testing, and the CAFT. Results from these evaluations suggested that (a) habituation to the CAFT was negligible; (b) prediction of VO2max from the CAFT in fit subjects remains a problem and further equation development for this group may be necessary; (c) maximal step-test protocols do not result in unequivocal VO2max determinations and may lead to misclassification of fitness level; and (d) although the CAFT correlates highly to treadmill VO2max (r = 0.90), a relatively large standard error may result in as high as a 13% error in estimating VO2max and may lead to problems in classifying fitness in some populations (e.g., older unfit).

Adolescent↗
PubMed1992

Selection of a maximal test protocol to validate the Canadian Aerobic Fitness Test.

The purpose of this study was to select a maximal aerobic power test protocol with which to validate a submaximal step test prediction equation. Subjects (N = 129), males and females 15 to 69 years of age, performed one maximal step test and one maximal treadmill test. The maximal treadmill protocol yielded higher peak VO2, ventilation, heart rate, and RER values. An age-predicted maximum heart rate was achieved by 35% of subjects on the step test and 55% on the treadmill. An RER of 1.15 was attained by 22% of the subjects on the step test and 53% on the treadmill. Regression analysis indicated that the submaximal test was more predictive of VO2max when the maximum was attained using the treadmill rather than the maximal step protocol. Peak VO2 values obtained from subjects tested on the treadmill will be used to develop a new prediction equation for the Canadian Aerobic Fitness Test.

Adolescent↗
PubMed1991

Acute recovery profile of lung volumes and function after running 5 miles.

The purpose of this study was to characterize the acute changes and recovery profile of lung volumes and function subsequent to strenuous aerobic exercise. Eight experienced runners (X age = 25 yrs; wt = 73 kg; ht = 181 cm) completed three identical 5 mile runs. Determinations were made of forced vital capacity (FVC), residual volume (RV), closing capacity (CC), and pulmonary diffusion capacity (DLCO). Measurement of cardiac output (Q) and stroke volume (SV) occurred simultaneously with the 10 second DLCO breathhold maneuver. Measurements were obtained before and 5, 15 and 25 minutes after each run. FVC was reduced (-4.5%) 5 min post-run with a return to pre-run values by 15 min. CC (+16%) and RV (+18%) remained elevated for at least 30 min post-run. DLCO did not appear to be effected by the run. However, the single-breath DLCO breathhold maneuver consistently caused a fall in SV at rest and during recovery. The hypothesis has been forwarded that an increase in central blood volume post-run accounted for the acute reduction in FVC. The sustained elevation in RV resulted from early closure of the small airways possibly due to an increase in extra-vascular lung water.

Adult↗
PubMed1991

Exercise training programs and cardiorespiratory adaptation.

Prudent, proper, and progressive aerobic exercise can improve the efficiency of the cardiorespiratory system. Several physiologic mechanisms interact to enhance the body's functional capabilities. Central cardiac adaptations such as improved pump efficiency and peripheral adjustments related to efficient energy transfer are the principle manifestations of proper exercise training. Related benefits of physical activity include reduction in risk from life style-related diseases, increased energy reserves for the activities of everyday living, and an improved quality of life. Functional exercise testing when administered properly can be used to establish safe exercise prescriptions, evaluate patients at risk, and determine program efficacy. The method of choice is a maximal exercise stress test with direct determination of oxygen uptake. Results from such evaluations help to accurately and safely determine the appropriate exercise prescriptions and establish a patient's physiologic profile. The exercise prescription should encompass an approach that denotes the proper application of frequency, intensity, duration, and mode of exercise. For the noncompetitive athlete, training programs should begin with a gentle progression of low-level intensity activities that encourages compliance and reduces risk. Short-term reachable goals documenting gradual increases in activity have been shown to be successful in terms of compliance and desired benefits. Although intense exercise training may be an ambitious goal for many persons, moderate levels of habitual physical activity are a more realistic goal. The clinician should realize that habitual physical activity is an integral part of a healthy life style. Lack of fitness has been strongly associated with all-cause morbidity and mortality. Obviously, the health potential of exercise cannot be realized if a society remains inactive. It is estimated that 40% of Americans are completely sedentary and another 40% are active at levels well below a threshold that would produce gains in cardiovascular fitness and health. This situation exists even though the US Public Health Service has prioritized the importance of physical fitness and habitual physical activity in maintaining preventive health measures and population health status.

Adaptation, Physiological↗
PubMed1989

Cardiovascular responses to upper body exercise in normals and cardiac patients.

This review summarizes and contrasts the cardiovascular responses elicited during dynamic upper body exercise (UBE) with those associated with lower body exercise (LBE). Information was obtained from studies which utilized arm-crank and/or cycle ergometers. At any given submaximal oxygen uptake (VO2), cardiac output (Q) is similar for UBE and LBE; however, heart rate (HR) is higher and stroke volume (SV) lower during UBE. Peripheral resistance and systolic and diastolic blood pressure are greater during UBE. Maximal Q, HR, SV, workload, and VO2 are less for UBE. As observed with healthy individuals, cardiac patients experience greater physiological stress for any given VO2 during UBE. UBE offers a satisfactory but perhaps not equivalent alternative to LBE for evaluation of angina and ischemic responses to exercise. The central and peripheral responses to either upper or lower body exercise appear to be independent of the muscle mass but directly related to the ergometer specific relative exercise intensity. The control mechanisms which govern these responses appear to be a centrally mediated activation of medullary centers coupled with a chemoreflex arising in the exercising skeletal muscle.

Arm↗
PubMed1989

Physiological profiles of the Canadian National Judo Team.

The physiology of Canadian National Judo Team members is described. These athletes differed widely in body size (height 157.4-187.7 cm; mass 56.5-100.8 kg). Aerobic fitness (treadmill) was high (VO2max = 4.49 I.min-1; 59.2 mL.kg-I.min-I), but relative VO2max decreased with increasing body mass. Elite judoka of other nations (Australia, 53.2; Poland, 59.0; Norway, 58.5) had comparable aerobic fitness. Significant (p less than 0.05) correlations between upper- (arm cranking, PWC170) versus lower-body aerobic fitness (r = 0.48), and upper- versus lower-body anaerobic power (r = 0.89) and capacity (r = 0.88) (Wingate) were observed. Peak power output (AnPP = 9.3 W.kg-I) and anaerobic capacity (AnCap = 260 J.kg-I) during arm cranking averaged 80% of leg-cranking values (AnPP = 13.7 W.kg-I; AnCap = 320 J.kg-I). Upper-body strength (bench press, one repetition, maximum = 100 kg) was also associated with upper-body anaerobic power (r = 0.72). Judoka exhibit a high degree of aerobic and anaerobic conditioning, and a pattern of total body fitness that is specifically required for their sport.

Adolescent↗
PubMedDate not supplied

A study to validate the Canadian Aerobic Fitness Test.

Our purpose was to assess the validity of VO2 max values predicted from The Canadian Aerobic Fitness Test (CAFT) by comparing them with peak VO2 values measured during a maximal treadmill protocol. Male and female subjects, 15-69 yr (n = 129), performed two submaximal exercise tests (CAFT protocol), and one maximal treadmill test. There was no significant heart rate habituation between the first two CAFT protocols. Peak VO2 values measured during the treadmill test (TM) were significantly higher than those predicted from the CAFT whether the sample was analyzed overall or categorized by sex. When the sample was categorized by age group, all but groups 1 (15-19) and 6 (60-69) had treadmill peak VO2 values significantly higher than those predicted using Jetté's equation. Using treadmill measured peak VO2 scores as the gold standard, VO2 max predictions using the CAFT protocol and Jetté equation placed individuals of lower fitness levels more accurately than highly fit individuals, into one of five fitness categories.

Adolescent↗