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Biomedical subjects

C M Maresh

Publications and source records attributed to C M Maresh.

68 records · Page 4Linked to original sources
PubMed1988

Exercise responses after short- and long-term residence at 2,200 meters.

Submaximal and maximal exercise responses were examined in persons (age, 19-30 years) residing at a moderate altitude for different periods of time. Long-term residents (LTR; 44 males, 11 females) had lived continuously between 1,830 and 2,200 m for 2 years or longer before testing. Short-term residents (STR; 22 males, 30 females), previously lowlanders, arrived at 2,200 m within 10 to 21 days before testing. Incremented tests on a motor-driven treadmill were performed until voluntary exhaustion. Cardiorespiratory measures and ratings of perceived exertion (RPE) were examined at 60% and 100% of maximal oxygen uptake (VO2max). With the exception of minute ventilation (VE), which was higher (p less than 0.05) in STR females, maximal responses were comparable in STR and LTR females. All maximal responses were similar in STR and LTR males. Both VE and RPE at 60% VO2max were significantly higher in STR males and females than in their LTR counterparts. Plasma lipid responses to the maximal exercise may indicate a greater contribution of the triglyceride pool of adipose tissue to fatty acid mobilization during exercise in the LTR compared to STR male subjects.

Acclimatization↗
PubMed1985

Early exercise training in patients older than age 65 years compared with that in younger patients after acute myocardial infarction or coronary artery bypass grafting.

To evaluate potential benefits that elderly cardiac patients might gain from early exercise programs, 361 such patients were studied: group I--60 patients aged 44 years or younger; group II--114 patients aged 45 to 54 years; group III--111 patients aged 55 to 64 years; and group IV--76 elderly patients aged 65 years or older. All patients participated in a 12-week exercise program within 6 weeks of acute myocardial infarction or coronary artery bypass grafting. All patients performed symptom-limited exercise tests before and after completion of the exercise program. Between tests, elderly patients manifested significant differences in body weight (76.9 to 75.2 kg), percent body fat (22.3 to 20.8 kg), heart rate at rest (77 to 68 beats/min), maximal heart rate (126 to 138 beats/min), maximal METs (5.3 to 8.1), submaximal average double product (17,305 to 14,071), and submaximal average rating of perceived exertion (12 to 10 [p less than 0.05]). Magnitudes of change were similar among groups, although the elderly patient group had a significantly lower absolute physical work capacity at testing after training than the other 3 groups (p less than 0.05). In the 25 elderly patients who received beta-blocking drugs, METs increased from 5.1 to 7.8 (p less than 0.05). In the remaining 51 elderly patients not receiving beta-blocking drugs, METs increased from 5.4 to 8.2 (p less than 0.05). The magnitude of increase in patients who received beta-blocking drugs was not significantly different from that in patients not receiving beta-blocking drugs.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗
PubMed1985

Plasma vasopressin, renin activity, and aldosterone responses to maximal exercise in active college females.

The effect of maximal treadmill exercise on plasma concentrations of vasopressin (AVP); renin activity (PRA); and aldosterone (ALDO) was studied in nine female college basketball players before and after a 5-month basketball season. Pre-season plasma AVP increased (p less than 0.05) from a pre-exercise concentration of 3.8 +/- 0.5 to 15.8 +/- 4.8 pg X ml-1 following exercise. Post-season, the pre-exercise plasma AVP level averaged 1.5 +/- 0.5 pg X ml-1 and increased to 16.7 +/- 5.9 pg X ml-1 after the exercise test. PRA increased (p less than 0.05) from a pre-exercise value of 1.6 +/- 0.6 to 6.8 +/- 1.7 ngAI X ml-1 X hr-1 5 min after the end of exercise during the pre-season test. In the post-season, the pre-exercise PRA was comparable (2.4 +/- 0.6 ngAI X ml- X hr-1), as was the elevation found after maximal exercise (8.3 +/- 1.9 ngAI X ml- X hr-1). Pre-season plasma ALDO increased (p less than 0.05) from 102.9 +/- 30.8 pg X ml-1 in the pre-exercise period to 453.8 +/- 54.8 pg X ml-1 after the exercise test. In the post-season the values were 108.9 +/- 19.4 and 365.9 +/- 64.4 pg X ml-1, respectively. Thus, maximal exercise in females produced significant increases in plasma AVP, renin activity, and ALDO that are comparable to those reported previously for male subjects. Moreover, this response is remarkably reproducible as demonstrated by the results of the two tests performed 5 months apart.

Adult↗
PubMed1985

Aldosterone, cortisol, and electrolyte responses to hypobaric hypoxia in moderate-altitude natives.

Serum aldosterone, cortisol, and electrolyte concentration, and urinary aldosterone and electrolyte excretion responses were examined in seven low-altitude natives (LAN) (373 m or less, aged 19-25 yr) and nine moderate-altitude natives (MAN) (1,830-2,200 m, aged 19-23 yr) for 2 d at their own residence (home) altitude (PB 740 or 585 mm Hg, respectively) and later for 2 d during decompression at a simulated altitude of 4,270 m (PB 447 mm Hg). The LAN group demonstrated higher (p less than 0.05) serum cortisol concentrations and respiration rates, and lower (p less than 0.05) serum aldosterone and potassium, and urinary aldosterone, sodium, and potassium concentrations at certain times during decompression compared to their home responses. Moderate-altitude native responses, on the other hand, were generally unchanged. Manifestations of acute mountain sickness at PB 447 mm Hg were also significantly greater in the LAN group. Thus, it appears that the MAN subjects were influenced less by the drop in ambient oxygen tension associated with PB 447 mm Hg.

Acute Disease↗
PubMed1984

The value of early out-patient cardiac exercise programmes for the elderly in comparison with other selected age groups.

To evaluate potential benefits that elderly cardiac patients might gain from early exercise programs, 361 cardiac patients were studied. Seventy-six patients were older than 65 years (elderly). All patients participated in a 12 week exercise program within six weeks of myocardial infarction or cardiac surgery. All patients performed symptom limited exercise tests prior to and after completion of the exercise program. Comparison of pre- and post-training data revealed that elderly patients had significant decrease in body weight, percent body fat, resting heart rate, submaximal average double product, and submaximal average rating of perceived exertion, P less than 0.05. Maximal achieved heart rate and mets significantly increased, P less than 0.05. Comparison of magnitude of changes seen in the elderly with those of younger patients failed to reveal significant differences, P greater than 0.05. These results suggest that the benefits of early exercise program seen in younger patients may also be expected in elderly patients.

Adult↗
PubMed1984

Adrenocortical responses to maximal exercise in moderate-altitude natives at 447 Torr.

Serum hydrocortisone and aldosterone (Aldo) responses to maximal exercise were examined in six low-altitude natives (LAN) (373 m or less, aged 19-25 yr) and eight moderate-altitude natives (MAN) (1,830-2,200 m, aged 19-23 yr) at their residence (home) altitudes (740 and 587 Torr, respectively) and later in a hypobaric chamber at a simulated altitude of 4,270 m (447 Torr). After 2 days at their respective residence altitude and in the chamber, each subject exercised to voluntary exhaustion on the bicycle ergometer. Fluid intake was similar in both groups at all testing locations. Preexercise 24-h urinary Aldo was lower in both groups at 447 Torr but only significantly reduced in the LAN group. In general, the changes in maximum exercise cardiorespiratory variables were twice as large in LAN as in MAN subjects going from residence altitude to 447 Torr. Both serum hydrocortisone and Aldo concentrations were increased (P less than 0.01) after exercise in both groups at residence altitude and 447 Torr. Aldo was lower (P less than 0.05) postexercise at 447 Torr than at residence altitude in both groups, but this decrease was more pronounced (P less than 0.01) in the LAN group. Thus it appears that high-altitude Aldo concentrations are more like resident altitude values in MAN than in LAN subjects.

Acclimatization↗
PubMed1983

Maximal exercise during hypobaric hypoxia (447 Torr) in moderate-altitude natives.

Six low-altitude natives (LAN) (373 m or less, aged 19-25 yr) and eight moderate-altitude natives (MAN) (1830-2200 m, aged 19-23 yr) were studied at both their residence (home) altitude (740 Torr and 587 Torr, respectively) and in a hypobaric chamber at a simulated altitude of 4270 m (447 Torr). Following a 2-d adaptation period, subjects performed an incremented test on the cycle ergometer until voluntary exhaustion. Significantly (P less than 0.05) greater differences in percent change of maximum exercise variables (total exercise time, exercise intensity, VO2, VCO2, VE/VO2 and HR) were noted in the LAN group than in the MAN group, going from their residence altitude to 447 Torr. The decrement in VO2max was 15% in the MAN group compared to 34% in the LAN group. The anaerobic threshold (% VO2max), estimated from VE BTPS measurements, was similar in both groups at residence altitude and at 447 Torr. In the morning prior to exercise testing at 447 Torr, LAN subjects reported greater (P less than 0.001) symptoms of acute mountain sickness (AMS) than MAN subjects. Our results indicate that, with respect to maximum exercise performance, moderate-altitude natives are at an advantage during early adaptation to hypobaric hypoxia.

Adult↗
PubMed1979

Cardio-respiratory and perceptual recovery from a marathon run.

Seven male runners (21--42 years) were examined before and after the 1976 Boston Marathon to provide data concerning the cardio-respiratory and perceptual recovery from the performance. Treadmill runs, 30 min in duration, were administered 1 week prior to the marathon and 2--3, 6--7 and 13--15 days following. Treadmill speed was held constant and based on each runner's planned race pace. Maximal performance data were collected 1 week before and 2 weeks after the race. Data were analyzed using a 2-way ANOVA (4 thirty min run data collection periods and 3 exercise time points--5, 15 and 30 min) and "t" tests. Treatment effects were not observed for either HR or VE, however, perceived exertion (RPE) was significantly elevated 2--3 and 6--7 days post-marathon and VO2 was significantly lower at 13--15 days. HR and RPE showed significant time effects indicating a non-steady state response. None of the maximal test variables were significantly displaced. All variables were returned to pre-marathon levels by 13--15 days except VO2 which was lower. Aerobic capacity was not a limiting factor in the recovery from a marathon run. Muscle soreness and stiffness seem to be related to the increased perceptual ratings following a marathon run.

Adult↗
PubMed1977

Functional capabilities following coronary bypass surgery.

Changes in myocardial oxygen supply were evaluated in 19 patients following coronary by-pass surgery (CBS) for angina pectoris (AP). A symptom limited maximal functional graded exercise test (GXT) was performed before and 2-19 (X 7.5) months following CBS. After surgery the patients were urged to resume full activity and were individually managed in a 10-week "at home" exercise program. Increases were demonstrated for predicted oxygen uptake and work load (p less than .002), and rate pressure product (p less than .02) following CBS, suggesting increased myocardial blood flow. Terminal heart rate showed no significant increase. Of 16 patients exhibiting ST segment depression ( greater than or equal to .1 mV) with AP during GXT before surgery, 10 cases experienced total relief of both of these signs after surgery. A correlation between the pre-operative number of occluded coronary arteries (greater than 50%) and the degree of exercise induced ST segment depression revealed no significant trend. Additionally, no significant relationship was found between post-operative GXT results and the number of by-pass grafts performed on each patient. This study supports the premise that the effectiveness of CBS, in improving functional capacity, can be objectively evaluated by a non-invasive functional GXT.

Adult↗
PubMed1976

A comparison of myocardial function in former athletes and non-athletes.

Heart rate (HR), total electromechanical systole (Q-S2), left ventricular ejection time (LVET), pre-ejection period (PEP), and diastole (D) were compared in 350 former athletes and 156 non-athletes, age 27-74. The two cohorts had been equated according to habitual leisure time physical activity. Former athletes exhibited significantly longer Q-S2 and PEP at rest, and significantly lower HR and lengthened Q-S2, LVET, PEP, and D at one minute following a standard two minute step test (less than 0.05). Significantly differences were observed between athletes and non-athletes in the light and moderate activity categories. There were no significant differences between former athletes and non-athletes currently engaged in strenuous leisure time physical activity. Comparisons were made among the three levels of habitual leisure time physical activity with each group and revealed that HR was lower and Q-S2, LVET, PEP, and D were longer at rest and following exercise as the level of physical activity increased. There were more significant differences among former athletes than among non-athletes. Most of these differences were between light to moderate and light to strenuous levels of activity. The evidence suggests an advantage in myocardial function among former athletes compared to their non-athlete counterparts.

Adult↗
PubMedDate not supplied

Cortisol and testosterone concentrations in wheelchair athletes during submaximal wheelchair ergometry.

It is yet unknown how upper body exercise combined with high ambient temperatures affects plasma testosterone and cortisol concentrations and furthermore, how these hormones respond to exercise in people suffering spinal cord injuries. The purpose of this study was to characterize plasma testosterone and cortisol responses to upper body exercise in wheelchair athletes (WA) compared to able-bodied individuals (AB) at two ambient temperatures. Four WA [mean age 36 (SEM 13) years, mean body mass 66.9 (SEM 11.8) kg, injury level T7-T11], matched with five AB [mean age 33.4 (SEM 8.9) years, mean body mass 72.5 (SEM 13.1) kg] exercised (cross-over design) for 20 min on a wheelchair ergometer (0.03 kg resistance.kg-1 body mass) at 25 degrees C and 32 degrees C. Blood samples were obtained before (PRE), at min 10 (MID), and min 20 (END) of exercise. No differences were found between results obtained at 25 degrees C and 32 degrees C for any physiological variable studied and therefore these data were combined. Pre-exercise testosterone concentration was lower (P < 0.05) in WA [18.3 (SEM 0.9) nmol.l-1] compared to AB [21.9 (SEM 3.6) nmol.l-1], and increased PRE to END only in WA. Cortisol concentrations were similar between groups before and during exercise, despite higher rectal temperatures in WA compared to AB, at MID [37.21 (SEM 0.14) and 37.02 (SEM 0.08) degrees C, respectively] and END [37.36 (SEM 0.16) and 37.19 (SEM 0.10) degrees C, respectively]. Plasma norepinephrine responses were similar between groups. In conclusion, there were no differences in plasma cortisol concentrations, which may have been due to the low relative exercise intensities employed. The greater exercise response in WA for plasma testosterone should be confirmed on a larger population. It could have been the result of the lower plasma testosterone concentrations at rest in our group.

Adult↗