Thermoregulatory responses to exercise and warm water immersion in physically trained men with tetraplegia

OBJECTIVE: To compare thermoregulatory responses of highly trained men who are tetraplegic during 40 min exercise at 65% [Vdot]O(2) peak and 60 min immersion in 39 degrees C water. METHODS: Four physically trained men who are tetraplegic participated in three laboratory visits. The first visit involved familiarisation and then determination of [Vdot]O(2) peak using open circuit spirometry during an incremental test to exhaustion with each man propelling his sport wheelchair on a motor driven treadmill. The order of second and third visits was randomly allocated. Visit 2 involved 40 min of exercise at 65% [Vdot]O(2) peak propelling each man's sport wheelchair on treadmill. Visit 3 involved sitting immersed to nipple line in 39 degrees C water for 60 min. Venous blood was obtained pre, during and after each intervention and analyzed for haemoglobin, haematocrit and changes in plasma volume were calculated. Separated plasma was analyzed for noradrenalin and adrenalin (high performance liquid chromatography). Heart rate, rectal temperature, and sweat rate estimated from a sweat capsule placed on forehead (dew point hygrometry) were recorded throughout. RESULTS: [Vdot]O(2) peak and HR max of these subjects were 1.14+/-0.16 l.min(-1) and 99+/-4 b.min(-1) respectively. Heart rate preimmersion was 67+/-4 b.min(-1) rising to 75+/-4 b.min(-1) after 40 min and 87+/-3 b.min(-1) after 60 min immersion. Heart rate was 68+/-3 b.min(-1) pre-exercise rising to 91+/-5 b.min(-1) after 40 min exercise. Rectal temperature rose from 35.97+/-0.30 degrees C pre immersion to 37.32+/-0.51 degrees C after 60 min immersion, and from 36.42+/-0.20 degrees C pre-exercise to 36.67+/-0.19 degrees C after 40 min exercise. Haemoconcentration occurred during 40 min of exercise and haemodilution occurred throughout 60 min of water immersion. Three participants demonstrated no sweating on the forehead during immersion or exercise. One subject commenced sweating after 20 min exercise and after 5 min of immersion. CONCLUSION: Compared to exercise, immersion was associated with a lower heart rate, a lower plasma noradrenalin concentration and an expanded plasma volume. When considering exercise or warm water immersion as therapeutic modalities in men who are tetraplegic, attention should be paid to heat gain and changes in plasma volume.     

Effect of Exercise Intensity on Differentiated and Undifferentiated Ratings of Perceived Exertion During Cycle and Treadmill Exercise in Recreationally Active and Trained Women

The purpose of the study is to examine the effect of aerobic exercise intensity on components of the differentiated perceived exertion model in young women performing weight bearing and non-weight bearing aerobic exercise. Subjects were 18-25 yr old women who were recreationally active (n = 19; VO₂max = 33.40 ml·kg^-1·min^-1) and trained (N = 22; VO₂max = 43.3 ml·kg^-1·min^-1). Subjects underwent two graded exercise tests (GXT) on a treadmill and bike which were separated by 48 hours. RPE-Overall, -Legs, and -Chest, as well as oxygen uptake (VO₂) and heart rate were recorded each minute. Individual regression analyses were used to identify RPE-Overall,-Legs, and -Chest at 40, 60, 80% VO_2max/peak. Separate two factor (site (3) x intensity (3)) ANOVAs with repeated measures on site and intensity were computed for each training status. Furthermore, RPE responses were also examined with a one factor (site (3)) within subject ANOVA with repeated measure on site at the ventilatory breakpoint. For both the recreationally active and trained groups no significant differences were observed for RPE-Overall, -Legs, and -Chest during treadmill exercise. However, for cycling exercise results indicated that RPE-Legs was significantly greater at all exercise intensities than RPE-Overall and RPE-Chest for trained subjects while for recreationally active subjects RPE-Legs was only significantly higher at the highest exercise intensity. Responses at the ventilatory breakpoint during cycle exercise indicated that RPE-Legs was significantly greater than RPE-Chest and RPE-Overall for trained subjects but not for recreationally active subjects. Signal dominance was not observed at an intensity equivalent to the ventilatory breakpoint during treadmill exercise in either of the groups. In recreationally active and trained females signal dominance was demonstrated only during cycling exercise, but not during treadmill exercise. Signal integration could not be demonstrated during cycling and treadmill exercise at various intensities.

Key points

• RPE is a valid tool to track relative exercise intensity and can be applied as differentiated and undifferentiated responses regardless of training status.
• RPE-Legs dominated the signal response in trained women during cycling exercise.
• RPE-Legs, -Chest, and -Overall did not differ significantly in trained and recreationally active women during treadmill exercise.
• RPE-Legs and -Chest contribute equally to the formation of RPE-Overall during cycling and treadmill exercise.

Key words: Aerobic exercise, physical exertion, oxygen consumption, physical fitness     

Hemodynamic evaluation of the Monostrut and spherical disc Bj?rk-Shiley aortic valve prosthesis with Doppler echocardiography.

A Doppler echocardiographic study was performed to assess whether the Monostrut model of the Bj?rk-Shiley valve (Shiley, Inc., Irvine, Calif.) had an improved hemodynamic performance in comparison with the spherical disc model in the aortic position. Twenty retrospectively randomly selected patients were studied, 10 with each valve type. Within each valve type two sizes of valve were studied, 21 and 23 mm. The two groups were comparable with respect to age, postoperative time, fractional shortening, New York Heart Association functional class preoperatively, and body surface area. Pulsed and continuous wave Doppler measurements were recorded at rest. Continuous wave Doppler recordings were performed every 2 minutes after exercise with supine bicycle ergometry until 10 minutes after exercise. Peak and mean gradients across the aortic valve prostheses were estimated. Both groups achieved a significant and comparable rise in heart rate with exercise. The mean gradients +/- standard error of the mean at rest and 2 minutes after exercise were 19.7 +/- 1.9 mm Hg and 30.9 +/- 2.2 mm Hg, respectively in the spherical disc group compared with 14.9 +/- 1.1 mm Hg and 23.6 +/- 1.7 mm Hg in the Monostrut group (p < 0.05 and p < 0.025, respectively). Peak transvalvular gradient at rest was 30.7 +/- 2.7 mm Hg in the spherical group compared with 23.9 +/- 1.9 mm Hg in the Monostrut group (p < 0.05). We conclude that the Monostrut Bj?rk-Shiley valve prosthesis has better hemodynamic performance than the spherical disc model in the aortic position.     

Effect of deconditioning on cortical and cancellous bone growth in the exercise trained young rats.

Exercise enhances bone growth and increases peak bone mass. The aim of this study was to determine whether or not 4 weeks of deconditioning after 8 weeks of exercise in growing rats would result in a decrease in bone gain or reverse the benefits of exercise. Fifty 4-week-old female Sprague-Dawley rats were randomized by a stratified weight method into 5 groups with 10 rats in each group: 8 weeks exercise (8EX), 8 weeks sedentary control (8S), 12 weeks exercise (12EX), 8 weeks exercise followed by 4 weeks sedentary (8EX4S), and 12 weeks sedentary control (12S). The exercise consisted of running on a treadmill with a 5 degrees slope at 24 m/minute for 1 h/day and 5 days/week. After each period of exercise, cancellous and cortical bone histomorphometry were performed on double fluorescent labeled 5-microm-thick sections of the proximal tibia and 40-microm-thick sections of the tibial shaft, respectively. Eight and 12 weeks of exercise resulted in a significant increase in the body weight and gastrocnemius muscle weight by two-way analysis of variance (ANOVA). The femoral wet weight (mg; mean +/- SD; 8EX, 781 +/- 45.1 vs. 8S, 713 +/- 40.5; p < 0.05; 12EX, 892 +/- 41.6 vs. 12S, 807 +/- 19.8; p < 0.05) was significantly higher in the exercise group than that in the respective control groups. The femoral wet weight and bone volume (BV) of the 8EX4S group (818 +/- 46.2 mg and 531 +/- 31.2 microl, respectively) were significantly lower than those of the 12EX group (p < 0.05) and did not differ significantly from those of the 12S groups. The cancellous BV was significantly higher in the 8EX and 12EX groups than that in the respective sedentary groups (p < 0.05). The cortical bone area of the tibial shaft was also significantly higher in the 12EX than that in the 12S group (p < 0.05). The increase in the cancellous BV or cortical bone area was caused by an increase in the mineral apposition rate (MAR), without a significant effect in the labeled perimeter. The bone formation rate (BFR; microm3/microm2 per day) in the cancellous bone (12EX, 27.9 +/- 7.74 vs. 12S, 15.4 +/- 4.56; p < 0.05) or periosteal surface (12EX, 127.6 +/- 27.7 vs. 12S, 79.5 +/- 18.6; p < 0.05) was significantly higher in the exercised groups than that in the respective control group (p < 0.05). Again, deconditioning resulted in a decrease in the cancellous BFR, BV, periosteal BFR, and cortical bone area to levels not significantly different from the 12S group. In conclusion, our findings showed that exercised growing rats, when deconditioned, lost the benefits gained through exercise and their bone parameters were reduced to levels not different from the sedentary control. Thus, continued exercise is required to maintain high bone mass.     

Differential effect of treadmill exercise on three cancellous bone sites in the young growing rat

The aim of the present study was to examine cancellous bone changes induced by exercise on three different skeletal sites, the lumbar vertebra, the proximal, and the distal tibia, in the young growing rat. Forty 4-week-old female Sprague-Dawley rats were randomized into 4 groups of 10 animals each; 8 weeks exercise (8EX), 8 weeks sedentary control (8CON), 12 weeks exercise (12EX), and 12 weeks sedentary control (12CON). The exercise regimen consisted of treadmill running at 24 m/min 1 hr per day 5 days a week. After each period of exercise, the proximal and distal tibial metaphyses (PTM and DTM, respectively) and the fifth lumbar (L5) vertebral body were processed for histomorphometry of the cancellous bone (secondary spongiosa) and cortical periosteum. Eight and twelve weeks of exercise significantly increased the mineral apposition rate and bone formation rate in the PTM and DTM, and 12 weeks of exercise significantly increased the labeled perimeter in the DTM, compared with the age-matched controls. Eight and twelve weeks of exercise significantly increased cancellous bone volume in the PTM (mean +/- standard deviation, 8EX; 19.1 +/- 2.9% vs 8CON; 14.3 +/- 3.1%, P < 0.05 and 12EX; 18.8 +/- 3.5% vs 12CON; 15.2 +/- 3.3%, P < 0.05), and 12 weeks exercise significantly increased cancellous bone volume in the DTM, compared with age-matched control (12EX; 32.5 +/- 7.7%, 12CON; 22.2 +/- 4.8%, P < 0.05). The increase in cancellous bone volume by 12 weeks exercise was higher in the DTM than that in the PTM (43.4% and 24.0%, respectively). On the other hand, the exercise did not significantly affect cancellous bone volume and bone formation in the L5 vertebral body, although the cortical periosteal bone formation rate and the L5 vertebral bone mass were increased. These findings suggest that cancellous bone adaptation to treadmill exercise is site specific, and the effect may be influenced by factors such as mechanical loading and metaphyseal bone architecture in the young growing rat.     

Exercise and thiazolidinedione therapy normalize insulin action in the obese Zucker fatty rat

Thiazolidinediones and exercise are both known to improve insulin action independently. Therefore, we determined whether combined therapy could normalize insulin action in the Zucker fatty (ZF) rat. Rats were fed troglitazone as a 0.2% food admixture over a 3-week exercise training period (treadmill running 5 days/week, 20 m/min, 0% grade, 60 min/day). Subsequent to drug and/or exercise therapy, animals were chronically cannulated in the carotid artery (sampling) and jugular vein (infusion). After a 4-day recovery from surgery, animals were exposed to a hyperinsulinemic (40 mU x kg(-1) x min(-1)) euglycemic clamp (8.5 +/- 0.12 mmol/l; P = 0.45 between groups). Independently, exercise (n = 7) and troglitazone (n = 7) improved the glucose disposal rate 20% (P = 0.04) and 76% (P = 0.001), respectively, when compared with untreated ZF controls (n = 11). In combination, exercise and troglitazone therapy (n = 6) produced significant increments in the following: tracer-determined glucose disposal rate (combined therapy, 52.4 +/- 2.9 mg x kg(-1) x min(-1), vs. untreated ZF, 25.8 +/- 0.8 mg x kg(-1) x min(-1); P = 0.0001), total GLUT4 protein (twofold increase; P = 0.001), insulin receptor substrate (IRS)-1 protein (fourfold increase; P = 0.0001), and Akt phosphorylation (2.9-fold increase; P = 0.002). In conclusion, 1) exercise and troglitazone therapy each improved insulin action in the ZF rat, whereas the combination of the two led to complete normalization of insulin sensitivity, and 2) combination treatment also resulted in normalization of GLUT4 total protein, IRS-1 protein, and Akt phosphorylation compared with lean littermates.     

Effect of anaerobic and aerobic exercise promoted by computer regulated functional electrical stimulation (FES) on muscle size, strength and histology in paraplegic males

The influence of anaerobic and aerobic exercise, promoted by computer regulated functional electrical stimulation (FES) was evaluated in four paraplegic males. Quadriceps muscle bulk was monitored by serial computerised axial tomography (CT) scanning and histology by muscle biopsies from the vastus intermedius. Anaerobic exercise consisted of 60 degree straight leg raising against increasing weights (range 1.4-11.4 kg) over a period of ten weeks. Aerobic exercise consisted of pedalling a modified Monark bicycle ergometer at 50 rpm against a fixed load ranging from 0-3/8 kilopond (0-18.75 watts) over a period of eight months. In both exercise studies the same work was not achieved by each paraplegic. FES was regulated by a closed loop system which is not presently commercially available, the frequency of the sequential muscle stimulator was 40 Hz with a pulse width of 300 microseconds. Quadriceps muscle area of both legs increased 62.7% (p less than 0.01) after anaerobic exercise; similar but less pronounced effects followed aerobic exercise. Histologically two distinct patterns were noted from the outset, one had normal fibre type distribution the remainder had marked Type 1 loss. Both exercise regimens failed to change these although the number of internal nuclei per 100 fibres steadily increased (from 7.0% to 13.8% to 26.0%) as did the % of fibres with internal nuclei (5.4% to 10.5% to 25.7%) throughout the exercise periods. The significance of these observations is not immediately apparent but may signify continuing damage which may be due to the eccentric rather than the concentric nature of FES promoted muscular contraction.     

Carvedilol does not modulate moderate exercise-induced hyperkalemia in hemodialysis patients

BACKGROUND AND AIM: Non-selective beta-adrenergic blockers may cause hyperkalemia in patients with end-stage renal failure. In contrast, alpha-adrenergic blockade has been found to decrease the hyperkalemic effect of physical exercise in healthy subjects, although we were unable to confirm this effect in hemodialysis patients. In a crossover design, we studied the effect of carvedilol, a non-selective beta-adrenergic blocker with an additional alpha1-blocking activity, on exercise-induced hyperkalemia in 17 anuric hemodialysis patients. METHODS: All subjects were given either carvedilol (25 mg/day) or placebo for 2 weeks in a random order with a 2-week wash-out period. At the end of each treatment period they underwent a 30-minute exercise test on a bicycle ergometer with a fixed load of 20 W. RESULTS: The treatment with carvedilol caused a significant decrease in blood pressure. Serum potassium before exercise tests was similar (5.37 +/- 0.2 and 5.24 +/- 0.2 mmol/l on carvedilol and placebo, respectively; mean +/- SE). During the exercise, serum potassium increased significantly (p < 0.001 in both tests) and subsequently decreased during 30 minutes of recovery (p < 0.05). The mean rate of potassium increment during the exercise was similar (23.3 +/- 3.3 micromol/l/min on carvedilol and 20.0 +/- 3.6 micromol/l/min on placebo). During recovery, the mean rate of potassium decrement was 5.0 +/- 3.0 micromol/l/min and 6.7 +/- 2.7 micromol/l/min, respectively. Serum sodium, ionized calcium, insulin and plasma renin activity were similar before the exercise tests and did not change during the exercise. CONCLUSION: Carvedilol does not enhance the hyperkalemic effect of moderate physical exercise in anuric hemodialysis patients.     

Adenosine, methacholine, and exercise challenges in children with asthma or paediatric chronic obstructive pulmonary disease.

BACKGROUND--Bronchial hyperreactivity to methacholine is present in children with asthma and other types of paediatric chronic obstructive pulmonary disease (COPD), while hyperreactivity to exercise is more specific for asthma. Adenosine 5'-monophosphate (AMP) is a potent bronchoconstrictor and, like exercise, may provoke asthma by activating mast cells. This study investigated the suitability of AMP as a specific challenge for asthma in children. METHODS--Bronchial provocation challenges with methacholine and AMP were performed in a double blind fashion using tidal breathing in 51 children with asthma, 21 with paediatric COPD of various types, and in 19 control children. Each subject also underwent a standardised exercise challenge after inhalation challenges were completed. Sensitivity and specificity curves were constructed and the intersection point of sensitivity and specificity for each type of challenge was determined. RESULTS--When the asthmatic patients were compared with the children with COPD, the intersection points for AMP, exercise and methacholine were 90%, 85%, and 50%, respectively. When compared with the controls the same intersection points were 98%, 84%, and 92%, and when children with paediatric COPD were compared with controls they were 55%, 50%, and 82%. CONCLUSIONS--Methacholine distinguishes both asthma and paediatric COPD from controls with a sensitivity of 82-92%, but does not distinguish between asthma and paediatric COPD; exercise and AMP distinguish asthma from controls with a sensitivity and specificity of 84-98% but they also distinguish asthma from paediatric COPD with a sensitivity and specificity of 85-90%. AMP inhalation is a practical aid for diagnosing asthma and distinguishing it from COPD in children of all ages.     

The haemodynamic response to submaximal exercise during isovolaemic haemodialysis.

INTRODUCTION: Exercise during haemodialysis has potential benefits but may compromise cardiovascular stability. We studied its acute effects on relative blood volume (RBV) and other haemodynamic parameters. METHODS: Two groups of 10 patients were exercised submaximally using a stationary cycle during isovolaemic dialysis whilst RBV was monitored continuously. In study 1, patients exercised for two 10 min periods separated by 10 min rest. Cardiac output (CO), peripheral vascular resistance (PVR), central blood volume (CBV) and stroke volume were measured using ultrasound dilution immediately before and after each exercise session. In study 2, haemoglobin, serum total protein and albumin levels were measured before and immediately after the exercise session and at the nadir of the RBV trace. RESULTS: RBV fell immediately on exercise initiation, the maximum reduction being 2.0+/-1.1% (after 5.9+/-1.4 min of exercise 1: P<0.001) and 2.0+/-1.2% (after 4.7+/-2.3 min of exercise 2: P<0.001). CO increased significantly after both periods of exercise (4.5+/-0.96 and 5.1+/-1.1 to 7.2+/-2.1 and 7.9+/-2.4 l/min, P<0.001 in both). Stroke volume increased significantly and PVR fell significantly during exercise. CBV increased in absolute terms but fell as a proportion of CO. Mean haemoglobin level at the RBV nadir was significantly higher than baseline (12.3+/-1.8 vs 11.8+/-1.7 g/dl: P<0.05: mean change 4.4+/-2.3%), as was mean total protein concentration (66.0+/-6.9 vs 62.0+/-8.1 g/l: P = 0.001: mean change 6.8+/-5.9%) and mean serum albumin concentration (36.0+/-3.9 vs 34.1+/-3.9 g/l: P<0.001: mean change 5.8+/-3.5%). CONCLUSION: The haemodynamic response to exercise during haemodialysis is comparable with that in normal individuals. The rapid reduction in RBV on exercise occurs in spite of a significant increase in CO, mainly as a consequence of fluid shifts from the microvasculature to the interstitium.     

Biochemical composition of equine carpal articular cartilage is influenced by short-term exercise in a site-specific manner

It was hypothesized that cartilage macro-molecular characteristics are influenced by exercise intensity and by location within a joint. OBJECTIVE: To determine the macromolecular characteristics of carpal articular cartilage at common and uncommon sites of pathology in horses undergoing high or low intensity exercise, and to compare this composition between exercise groups. DESIGN: Twelve horses (19.3+/-0.9 years) were assigned to exercise groups. Each group underwent 19 weeks high-intensity treadmill training (N=6) or low-intensity exercise (N=6). Dorsal and palmar test sites were identified on radial, intermediate and third carpal articular surfaces after euthanasia. Cartilage was collected from each site, freeze-dried and assessed for water content. Hydroxyproline, glycosaminoglycan and DNA analyses were performed on cartilage from each test site. Adjacent cartilage underwent histological preparation and assessment for chondrocyte numerical density at each site and proteoglycan distribution through the depth of cartilage. RESULTS: Dorsal cartilage had a higher collagen content, DNA content, and chondrocyte numerical density, but lower glycosaminoglycan content than palmar cartilage. Cartilage from horses undergoing high-intensity training had a significantly higher glycosaminoglycan content than cartilage from horses undergoing low-intensity exercise, with maximal difference being observed in cartilage from dorsal radial and dorsal intermediate carpal articular surfaces. Overall no effect of exercise on collagen was observed, but at sites predisposed to clinical lesions cartilage from horses undergoing high-intensity training contained significantly less collagen than from horses undergoing low-intensity exercise. Distribution of proteoglycan was non-uniform in 52% of the sections examined, with superficial loss of toluidine blue staining primarily at dorsal sites and in the high-intensity exercise group. CONCLUSIONS: These results indicate that topographical and exercise related differences exist in carpal cartilage composition, and that the effect of exercise on overall composition and distribution within the cartilage was maximal at sites predisposed to clinical lesions. These findings could indicate that the combined effect of exercise and local load variations within a joint may lead to a risk of exceeding the physiologic threshold at high load sites that are predisposed to clinical injury.     

The effect of trunk resistive exercise on muscle strength in postmenopausal women

At the time this study was conducted. Ms. O'Dwyer and Ms. Lin were physical therapy master's degree students. Dr. Blanpied was a doctoral student. This paper was presented at the First International Orthopaedic Symposium in Ottawa, Canada, in May, 1990. This study was supported by Grant RR59 from the General Clinical Research Centers Program, Division of Research Resources, NIH, and by an Aging Seed Grant from The University of Iowa.Fifty-five women with an average age of 56 years participated in a study to determine the effects of a quantitatively based home exercise program on trunk muscle strength. The same body positions were used for testing trunk strength and for the exercise program. During the strength tests, the external forces generated by the subjects were measured using the trunk attachment of the Muscle Evaluation and Exercise Dosimeter (MEED) 3000 System. The standardized exercise program utilized the body segments and cuff weights on the extremities to achieve the desired resistance level for the sit-up, prone trunk extension, and double-leg flexion exercises. Three sets of 10 were performed for each exercise at least three times a week over a 12-month period. Large, significant (p < .05) strength gains (25-30%) were made by the exercise group for each exercise. The performance of the exercise group was superior to the control group. The reliability of the strength-using tests determined by interday trials using the MEED 3000 was high-all correlations were r = .93 or higher. This study demonstrates that older women can tolerate and increase trunk muscle strength using controlled, progressive, resistive exercise over a long period of time. The exercise approach in this study might be considered for use in treatment of low back dysfunction. J Orthop Sports Phys Ther 1991;13(6):300-309.     

Resistance exercise and insulin regulate AS160 and interaction with 14-3-3 in human skeletal muscle

A single bout of aerobic exercise can enhance insulin action, but whether a similar effect occurs after resistance exercise is unknown. Hyperinsulinemic-euglycemic clamps were performed on eight male subjects at rest and after a single bout and three repeated bouts of resistance exercise over 7 days. Skeletal muscle biopsies were taken before and after the clamp and immediately after a single exercise bout. Whole-body insulin action measured by glucose infusion rate decreased (P < 0.05) after a single exercise bout, whereas in response to repeated bouts of resistance exercise, the glucose infusion rate was similar to the rest trial. In skeletal muscle, Akt substrate of 160 kDa (AS160) phosphorylation, an Akt substrate implicated in the regulation of GLUT4 translocation, and its interaction with 14-3-3 was decreased (P < 0.05) only after a single exercise bout. Insulin increased (P < 0.05) phosphorylation of AS160 and its interaction with 14-3-3, but the insulin response was not influenced by resistance exercise. Phosphorylation of insulin receptor substrate-1 and Akt were similar to changes in AS160 phosphorylation after exercise and/or insulin. In conclusion, a single bout of resistance exercise impairs whole-body insulin action. Regulation of AS160 and interaction with 14-3-3 in skeletal muscle are influenced by resistance exercise and insulin but do not fully explain the effect of resistance exercise on whole-body insulin action.     

Thoracic epidural anesthesia improves global and regional left ventricular function during stress-induced myocardial ischemia in patients with coronary artery disease

The aim of the present investigation was to study the effects of high thoracic epidural anesthesia (TEA), including the cardiac sympathetic segments, on ischemic ST-segment changes and left ventricular global and regional wall motion abnormalities. Ten patients with a two- or three-vessel coronary artery disease, all treated with the beta-adrenergic blocker metoprolol because of severe stable angina pectoris, performed two identical exercise stress tests, the first without TEA (control exercise) and the second with TEA (TEA exercise). Before each stress test, intravenous metoprolol was given to achieve maximal or near maximal beta-adrenoceptor blockade. Systolic and diastolic arterial pressures (radial artery cannula), heart rate, and rate-pressure product, as well as global and regional ejection fractions, using equilibrium radionuclide angiography in the left anterior oblique projection, were measured at rest and during maximal exercise. ST-segment analysis (V3 or V5) was performed, and the regional wall motion score was calculated at control exercise and TEA exercise. Intravenous metoprolol or intravenous metoprolol plus TEA at rest did not cause any significant changes of any of the variables. During TEA exercise, systolic arterial pressure, diastolic arterial pressure, and rate-pressure product, but not heart rate, were significantly lower compared to control exercise. The global and anterolateral ejection fractions were significantly higher (52.8% versus 46.5% and 53.2% versus 46.0%, respectively, P less than 0.05), and the regional wall motion score was significantly lower (8.8 versus 11.8, P less than 0.01) during TEA exercise than during control exercise. ST-segment depression was significantly lower during TEA exercise (-1.03 versus -1.84 mV, P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)     

Performance, ventilation, and oxygen consumption in three different types of exercise test in patients with chronic obstructive lung disease.

Seventeen patients (six men and 11 women, mean age 66 years) with severe chronic obstructive lung disease (mean FEV1 0.8 (SD 0.3)1) performed three different types of exercise test on four occasions within one week. Three daily doses of placebo tablets were given between the third and fourth attempt at each test. The tests were the 12 minute walking test, a fixed rate and height paced step test, and a cycle ergometer test in which the work rate was increased by 10 watts each minute. Performance increased significantly (p less than 0.01) between the first and fourth attempts in each type of test (12 min walking distance 16% (SD 20%); steps climbed 96% (74%); duration of cycling 29% (41%]. There was a trend for the increase in performance between successive attempts to become progressively smaller but this was not significant. No effect of placebo on exercise performance was detected. The greatest intersubject range of performance was seen in the step test (14-126 steps) and the least in the walking test (438-1014 m). Significant correlations (p less than 0.01) were observed between performance in all three types of exercise test, but the correlations found between the results of the various tests of exercise performance and the FEV1 and the FVC were either weak (p less than 0.05) or non-significant. Ventilation (VE) and oxygen consumption (VO2) were subsequently measured and compared in eight patients during all three types of exercise test. Both the VE and the VO2 that were achieved in the step test were significantly greater than in either the cycle or the walking test. No patient was able to reach and sustain steady state values of VE and VO2 in the step test, whereas a steady state for both VE and VO2 was reached and sustained by all eight patients in the walking test. It is suggested that at least three practice attempts at any exercise test should be made before the introduction of either placebo or specific pharmacological treatment and that even then it may be necessary to allow for the effects of further repeated testing in the assessment of the results of treatment.     

Acute exercise induces GLUT4 translocation in skeletal muscle of normal human subjects and subjects with type 2 diabetes.

Total GLUT4 content in skeletal muscle from individuals with type 2 diabetes is normal; however, recent studies have demonstrated that translocation of GLUT4 to the plasma membrane is decreased in response to insulin stimulation. It is not known whether physical exercise stimulates GLUT4 translocation in skeletal muscle of individuals with type 2 diabetes. Five subjects (two men, three women) with type 2 diabetes and five normal control subjects (5 men), as determined by a standard 75-g oral glucose tolerance test, were recruited to determine whether an acute bout of cycle exercise activates the translocation of GLUT4 to the plasma membrane in skeletal muscle. Each subject had two open biopsies of vastus lateralis muscle; one at rest and one 3-6 weeks later from the opposite leg after 45-60 min of cycle exercise at 60-70% of VO2max. Skeletal muscle plasma membranes were prepared by subcellular fractionation, and GLUT4 content was determined by Western blotting. Plasma membrane GLUT4 increased in each subject in response to exercise. The mean increase in plasma membrane GLUT4 for the subjects with type 2 diabetes was 74 +/-20% above resting values, and for the normal subjects the increase was 71+/-18% above resting values. Although plasma membrane GLUT4 content was approximately 32% lower at rest and after exercise in the muscle of the subjects with type 2 diabetes, the differences were not statistically significant. We conclude that in contrast to the previously reported defect in insulin-stimulated GLUT4 translocation in skeletal muscle of individuals with type 2 diabetes, a single bout of exercise results in the translocation of GLUT4 to the plasma membrane in skeletal muscle of individuals with type 2 diabetes. These data provide the first direct evidence that GLUT4 translocation is an important cellular mechanism through which exercise enhances skeletal muscle glucose uptake in individuals with type 2 diabetes.     

术前快速康复操对腹腔镜结直肠癌根治术后恢复的影响

目的 观察术前进行快速康复操的锻炼对腹腔镜结直肠癌根治术患者术后恢复的影响.方法 选择拟行腹腔镜下结直肠癌根治手术患者200例,男122例,女78例,年龄32～80岁,ASAⅠ—Ⅲ级.随机分为两组:康复操组与对照组,每组100例.康复操组在术前进行快速康复操的锻炼,对照组仍采用传统的术前干预方案.两组患者均采用静-吸复...     

A 6-Mo Home-Based Exercise Program May Slow Vertebral Height Loss

Twenty-one of 46 postmenopausal women were assigned to a home-based exercise program consisting of 60 min of exercise, 3 d/wk. The 25 nonexercisers continued usual daily activities. Each woman had at least one prevalent vertebral fracture and suffered from osteoporosis as defined by the application of WHO criteria to lumbar spine bone mineral density. Vertebral heights were measured using bone densitometry at baseline and 12 mo later. Vertebrae T9 to L4 were all identified for each of the 46 subjects in both the baseline and end-of-study lateral scans. The change in mean vertebral height over the course of the study was -0.3 mm anteriorly, -0.7 mm at the mid-location, and -0.4 mm posteriorly for the nonexercisers. For the exercisers, the corresponding changes were +0.1 mm anteriorly, -0.3 mm at the mid-location, and +0.2 mm posteriorly. The benefit of exercise in preserving vertebral morphometry in patients with osteoporosis deserves further investigation.     

Salivary Cortisol Responses and Perceived Exertion during High Intensity and Low Intensity Bouts of Resistance Exercise

The purpose of this study was to measure the salivary cortisol response to different intensities of resistance exercise. In addition, we wanted to determine the reliability of the session rating of perceived exertion (RPE) scale to monitor resistance exercise intensity. Subjects (8 men, 9 women) completed 2 trials of acute resistance training bouts in a counterbalanced design. The high intensity resistance exercise protocol consisted of six, ten-repetition sets using 75% of one repetition maximum (RM) on a Smith machine squat and bench press exercise (12 sets total). The low intensity resistance exercise protocol consisted of three, ten-repetition sets at 30% of 1RM of the same exercises as the high intensity protocol. Both exercise bouts were performed with 2 minutes of rest between each exercise and sessions were repeated to test reliability of the measures. The order of the exercise bouts was randomized with least 72 hours between each session. Saliva samples were obtained immediately before, immediately after and 30 mins following each resistance exercise bout. RPE measures were obtained using Borg’s CR-10 scale following each set. Also, the session RPE for the entire exercise session was obtained 30 minutes following completion of the session. There was a significant 97% increase in the level of salivary cortisol immediately following the high intensity exercise session (P<0.05). There was also a significant difference in salivary cortisol of 145% between the low intensity and high intensity exercise session immediately post-exercise (P<0.05). The low intensity exercise did not result in any significant changes in cortisol levels. There was also a significant difference between the session RPE values for the different intensity levels (high intensity 7.1 vs. low intensity 1.9) (P<0.05). The intraclass correlation coefficient for the session RPE measure was 0.95. It was concluded that the session RPE method is a valid and reliable method of quantifying resistance exercise and that salivary cortisol responds promptly to the exercise load.

Key Points

• The present study showed that salivary cortisol responses were significantly different immediately post exercise between the low intensity and high intensity exercise sessions
• Salivary measures of cortisol can be used to delineate between high and low intensity resistance exercise bouts.
• The session RPE method appears to be a reliable method of quantifying resistance exercise

Key words: Weight lifting, stress, endocrine effects