Anaerobic Threshold Intensity Research Articles

The effects of two different swimming training periodization on physiological parameters at various exercise intensities

This study analysed the effects of two different periodization strategies on physiological parameters at various exercise intensities in competitive swimmers. Seventeen athletes of both sexes were divided to two groups, the traditional periodization (TPG, n = 7) and the reverse periodization group (RPG, n = 10). Each group followed a 10-week training period based on the two different periodization strategies. Before and after training, swimming velocity (SV), energy expenditure (EE), energy cost (EC) and percentage of aerobic (%Aer) and anaerobic (%An) energy contribution to the swimming intensities corresponding to the aerobic threshold (AerT), the anaerobic threshold (AnT) and the velocity at maximal oxygen uptake (vVO2max) were measured. Both groups increased the %An at the AerT and AnT intensity (P ≤ .05). In contrast, at the AnT intensity, EE and EC were only increased in TPG. Complementary, %Aer, %An, EE and EC at vVO2max did not alter in both groups (P > .05); no changes were observed in SV in TPG and RPG at all three intensities. These results indicate that both periodization schemes confer almost analogous adaptations in specific physiological parameters in competitive swimmers. However, given the large difference in the total training volume between the two groups, it is suggested that the implementation of the reverse periodization model is an effective and time-efficient strategy to improve performance mainly for swimming events where the AnT is an important performance indicator.

Effects of a 12-week, short-interval, intermittent, low-intensity, slow-jogging program on skeletal muscle, fat infiltration, and fitness in older adults: randomized controlled trial.

We developed a short-interval, low-intensity, slow-jogging (SJ) program consisting of sets of 1min of SJ at walking speed and 1min of walking. We aimed to examine the effects of an easily performed SJ program on skeletal muscle, fat infiltration, and fitness in older adults. A total of 81 community-dwelling, independent, older adults (70.8±4.0years) were randomly assigned to the SJ or control group. The SJ group participants were encouraged to perform 90min of SJ at their anaerobic threshold (AT) intensity and 90min of walking intermittently per week. Aerobic capacity at the AT and sit-to-stand (STS) scores were measured. Intracellular water (ICW) in the legs was assessed by segmental multi-frequency bioelectrical impedance analysis. Subcutaneous (SAT) and intermuscular (IMAT) adipose tissue and muscle cross-sectional area (CSA) were measured at the mid-thigh using computed tomography. A total of 75 participants (37 SJ group, 38 controls) completed the 12-week intervention. The AT and STS improved in the SJ group compared with the controls (AT 15.7 vs. 4.9%, p<0.01; STS 12.9 vs. 4.5%, p<0.05). ICW in the upper leg increased only in the SJ group (9.7%, p<0.05). SAT and IMAT were significantly decreased only in the SJ group (p<0.01). The 12-week SJ program was easily performed by older adults with low skeletal muscle mass, improved aerobic capacity, muscle function, and muscle composition in older adults.

Melatonin Has An Ergogenic Effect But Does Not Prevent Inflammation and Damage In Exhaustive Exercise.

It is well documented that exhaustive physical exercise leads to inflammation and skeletal muscle tissue damage. With this in mind, melatonin has been acutely administered before physical exercise; nevertheless, the use of melatonin as an ergogenic agent to prevent tissue inflammation and damage remains uncertain. We evaluated the effects of melatonin on swimming performance, muscle inflammation and damage and several physiological parameters after exhaustive exercise at anaerobic threshold intensity (iLAn) performed during light or dark circadian periods. The iLAn was individually determined and two days later, the animals performed an exhaustive exercise bout at iLAn 30 minutes after melatonin administration. The exercise promoted muscle inflammation and damage, mainly during the dark period, and the exogenous melatonin promoted a high ergogenic effect. The expressive ergogenic effect of melatonin leads to longer periods of muscle contraction, which superimposes a possible melatonin protective effect on the tissue damage and inflammation.

Melatonin is an Ergogenic Aid for Exhaustive Aerobic Exercise only during the Wakefulness Period

This study tested the ergogenic effects of acute administration of melatonin on exhaustive exercise (tlim) at the anaerobic threshold intensity (iAnT) during periods of lower (L) and higher (H) spontaneous physical activity in swimming rats. Additionally, we evaluated the time of day effect on aerobic exercise tolerance. The periods of L and H were determined gravimetrically. All animals were subjected to an incremental test to determine the iAnT. Melatonin was administered (10 mg.kg(-1), intraperitoneal) and after 30 min, the rats were subjected to tlim during the L (LM) or H (HM) period. Control groups were called LC and HC. The criterion of significance was 5%. Melatonin enhanced tlim by 169% during H (HC=72 min; HM=194 min; P<0.01; ES=1.23) and by 90% during L (LC=31 min vs. LM=59 min; P=0.39; ES=1.18), demonstrating a significant effect on tlim (F=10.35; P<0.01) and a strong effect size (ES). Additionally, tlim was higher during H (F=14.24; P<0.01). Melatonin is a reasonable ergogenic aid, particularly during the wakefulness period, and the exercise tolerance is dependent on the time of day for swimming rats.

Active Female Maximal and Anaerobic Threshold Cardiorespiratory Responses to Six Different Water Aerobics Exercises

Purpose: Maximal tests conducted on land are not suitable for the prescription of aquatic exercises, which makes it difficult to optimize the intensity of water aerobics classes. The aim of the present study was to evaluate the maximal and anaerobic threshold cardiorespiratory responses to 6 water aerobics exercises. Volunteers performed 3 of the exercises in the sagittal plane and 3 in the frontal plane. Method: Twelve active female volunteers (aged 24 ± 2 years) performed 6 maximal progressive test sessions. Throughout the exercise tests, we measured heart rate (HR) and oxygen consumption (VO2). We randomized all sessions with a minimum interval of 48 hr between each session. For statistical analysis, we used repeated-measures 1-way analysis of variance. Results: Regarding the maximal responses, for the peak VO2, abductor hop and jumping jacks (JJ) showed significantly lower values than frontal kick and cross-country skiing (CCS; p < .001; partial η2 = .509), while for the peak HR, JJ showed statistically significantly lower responses compared with stationary running and CCS (p < .001; partial η2 = .401). At anaerobic threshold intensity expressed as the percentage of the maximum values, no statistically significant differences were found among exercises. Conclusion: Cardiorespiratory responses are directly associated with the muscle mass involved in the exercise. Thus, it is worth emphasizing the importance of performing a maximal test that is specific to the analyzed exercise so the prescription of the intensity can be safer and valid.

Effects of exercise at individual anaerobic threshold and maximal fat oxidation intensities on plasma levels of nesfatin-1 and metabolic health biomarkers

Exercise is recognized as an effective method of weight management and short-term appetite regulation tool. The effect of different exercise intensities on appetite regulation hormones in healthy overweight participants has not been intensively studied. The aim of this study was to examine the influence of exercise at individual anaerobic threshold (IAT) and maximal fat oxidation (Fatmax) intensities on the nesfatin-1 response and metabolic health biomarkers in overweight men. Nine healthy overweight males (age, 23.1 ± 1.1 years) volunteered in this study in a counterbalanced order. Blood samples were obtained before, immediately after, and following the first 45 min of recovery for measuring plasma variables. There was significant decrease in plasma levels of nesfatin-1 and leptin after exercise at the IAT intensity which remained lower than baseline following 45 min of recovery. However, nesfatin-1 and leptin levels did not change significantly in any time courses of Fatmax intensity (P > 0.09). Plasma interleukin-6 (IL-6) concentration increased during exercise in both intensities (P < 0.05), whereas changes in free fatty acids (FFAs) and epinephrine concentrations were significant only at the IAT. In addition, a significant correlation was found among nesfatin-1 levels with insulin (r = 0.39, P < 0.05) and glucose (r = 0.41, P < 0.05) at basal and in response to exercise. These results indicate that IAT has a greater exercise-induced appetite regulation effect compared with Fat(max). Based on these data, the intensity of exercise may have an important role in changes of nesfatin-1, leptin, FFA, and epinephrine concentrations even though this was not the case for IL-6 and insulin resistance.

Time to exhaustion at anaerobic threshold in swimming rats: metabolic investigation.

The purpose of this study was to determine the time to exhaustion (tlim) for swimming exercise at anaerobic threshold (AT) intensity in rats and to analyze metabolic consequences on serum and tissues levels. Eighteen rats were divided in control (CG) and exercised (EG) groups, being the former submitted to tlim. We analyzed the glycogen content of liver and ten skeletal muscles, as well as serum parameters. Parametric statistic was used with significance level at p < 0.05. The tlim, which was correspondent to 114.37 ± 36.23 min, promoted significant decrease in blood glucose (42.99 %; p < 0.01) and an increase in free fatty acids (167.12 %; p < 0.01) when EG was compared to CG. We did not find differences in albumin, total protein uric acid and creatinine between groups. The proposed exercise at individualized AT intensity promoted severe glycogen depletion for all tissues (mean of 78.05 % for all muscles and 89 % for liver). With substantial control of exercise intensity, our study establishes a useful rodent model that can be further explored, contributing to the advancement on knowledge and better understanding of exhaustion mechanisms.

Serum S100B level increases after running but not cycling exercise

The objective of this study was to investigate the effect of running versus cycling exercises upon serum S100B levels and typical markers of skeletal muscle damage such as creatine kinase (CK), aspartate aminotransferase (AST) and myoglobin (Mb). Although recent work demonstrates that S100B is highly expressed and exerts functional properties in skeletal muscle, there is no previous study that tries to establish a relationship between muscle damage and serum S100B levels after exercise. We conducted a cross-sectional study on 13 male triathletes. They completed 2 submaximal exercise protocols at anaerobic threshold intensity. Running was performed on a treadmill with no inclination (RUN) and cycling (CYC) using a cycle-simulator. Three blood samples were taken before (PRE), immediately after (POST) and 1 h after exercise for CK, AST, Mb and S100B assessments. We found a significant increase in serum S100B levels and muscle damage markers in RUN POST compared with RUN PRE. Comparing groups, POST S100B, CK, AST and Mb serum levels were higher in RUN than CYC. Only in RUN, the area under the curve (AUC) of serum S100B is positively correlated with AUC of CK and Mb. Therefore, immediately after an intense exercise such as running, but not cycling, serum levels of S100B protein increase in parallel with levels of CK, AST and Mb. Additionally, the positive correlation between S100B and CK and Mb points to S100B as an acute biomarker of muscle damage after running exercise.

Efeito das cargas de treinamento sobre parâmetros fisiológicos de futebolistas

O objetivo desse estudo foi verificar os efeitos de três semanas de treinamentos com intensidades monitoradas sobre a capacidade aeróbia de futebolistas profissionais. Quatorze futebolistas integrantes de equipe da primeira divisão do Campeonato Brasileiro de 2010, foram avaliados pré e pós três semanas de treinamento. O limiar anaeróbio (LAn) foi determinado pelo método bi-segmentado, para isso quatro esforços submáximos de 800 metros com intensidades de 10, 12, 14 e 16 km/h foram aplicados. Trinta três sessões de treinamentos foram quantificadas em zonas de acordo com frequência cardíaca referente ao LAn (FC LAn): Z1 - 10% abaixo, Z2 - 90-100% e Z3 - acima da FC LAn. Durante os treinamentos os jogadores permaneceram 31,17±14,86%, 42,96±14,90% e 25,87±16,67% em Z1, Z2 e Z3, respectivamente. Não foram encontradas diferenças significativas no LAn (pré = 13,29 ± 0,71 km∙h-1; pós=12,85 ± 0,90 km∙h-1), percepção subjetiva de esforço correspondente ao LAn (pré = 11,53 ± 1,45 u.a; pós=11,23 ± 1,53 u.a) e FC LAn (pré = 166,64 ± 10,69 bpm; pós = 174,50 ± 10,89 bpm), indicando que três semanas de treinamento são insuficiente para gerar adaptações positivas no LAn de futebolistas.

Critical load forced-swim test with Wistar rats does not properly estimate anaerobic threshold: The relationship with morphophysiological factors and performance indices

Summary Objective The study aimed to correlate morphophysiological characteristics associated with performance and indices associated with the critical power model, and to verify the time to exhaustion (Tlim) at critical load (CL) intensity. Methods Twenty male Wistar rats were submitted to four predictive tests to determine CL and anaerobic swim capacity (ASC) intensity using hyperbolic and Busso's models. Subsequently, they were submitted to exercise at 100% of CL intensity derived from hyperbolic model until exhaustion, and the time was recorded to the nearest second. The day after, animals were euthanized for blood and tissue collection. Results Significant relationships were found among the indices CL, ASC (derived from the both models) and Tlim (P 0.05). Conclusion We can conclude that the CL rat swimming model does not properly estimate the anaerobic threshold intensity. Furthermore, the correlations with morphophysiological variables indicate that none of variables alone can account for performance at CL intensity.

EFFECTS OF EXERCISE THERAPY AT THE INTENSITY OF ANAEROBIC THRESHOLD FOR CARDIOPULMONARY FUNCTION IN PATIENTS WITH AMI AFTER PERCUTANEOUS CORONARY INTERVENTION

ObjectivesThe purpose is to investigate the feasibility and safety of aerobic exercise prescription from the individually-based results of cardiopulmonary exercise test (CPET) and influence of aerobic exercise training for cardiopulmonary...

Effects of exercise therapy at the intensity of anaerobic threshold for exercise tolerance in patients with chronic stable coronary artery disease

To investigate the effects of exercise therapy at the intensity of anaerobic threshold (AT) for exercise tolerance in patients with chronic stable coronary artery disease. Forty-three patients with chronic stable coronary artery disease (3 patients after coronary arterial bypass graft (CABG) surgery, 22 patients with old myocardial infarction and 18 unstable angina pectoris undergoing successful percutaneous coronary intervention (PCI) finished twice cardiopulmonary exercise test (CPET) and followed their rehabilitation program for 3 months. Thirty-two patients finished their aerobic exercise therapy based on their individual anaerobic thresholds while 11 patients had no exercise therapy. The heart rate at AT intensity (97 ± 9/min) was lower than their traditional minimal target heart rate (112 ± 7/min) and lower than heart rate (115 ± 11/min) at ischemic threshold post-CPET. The O(2) consumption (10.7 ± 2.4 to 12.6 ± 2.9 ml×min(-1)×kg(-1)) (P = 0.04) and workload (37 ± 18 to 47 ± 13 J/s) (P = 0.04) at AT level and the O(2) consumption (15.3 ± 3.1 to 20.6 ± 4.2 ml×min(-1)×kg(-1), P = 0.02) and workload(68 ± 12 and 87 ± 14 J/s, P = 0.01) at peak level markedly increased after 3 months in the exercise group. And the O(2) consumption (15.3 ± 2.9 to 16.2 ± 3.1 ml×min(-1)×kg(-1)) and workload (65 ± 13 to 73 ± 16 J/s) at peak level mild increased after 3 months in the non-exercise group, but their O(2) consumption (11.0 ± 2.7 to 11.3 ± 2.8 ml×min(-1)×kg(-1)) and workload (38 ± 11 to 37 ± 9 J/s) at AT level had no obvious change. AT exercise intensity was lower than ischemic threshold post-CPET. Exercise therapy at the intensity of anaerobic threshold can improve oxygen capacity and exercise tolerance.

Exercise at anaerobic threshold intensity and insulin secretion by isolated pancreatic islets of rats

To evaluate the effect of acute exercise and exercise training at the anaerobic threshold (AT) intensity on aerobic conditioning and insulin secretion by pancreatic islets, adult male Wistar rats were submitted to the lactate minimum test (LMT) for AT determination. Half of the animals were submitted to swimming exercise training (trained), 1 h/day, 5 days/week during 8 weeks, with an overload equivalent to the AT. The other half was kept sedentary (sedentary). At the end of the experimental period, the rats were submitted to an oral glucose tolerance test and to another LMT. Then, the animals were sacrificed at rest or immediately after 20 minutes of swimming exercise at the AT intensity for pancreatic islets isolation. At the end of the experiment mean workload (% bw) at AT was higher and blood lactate concentration (mmol/L) was lower in the trained than in the control group. Rats trained at the AT intensity showed no alteration in the areas under blood glucose and insulin during OGTT test. Islet insulin content of trained rats was higher than in the sedentary rats while islet glucose uptake did not differ among the groups. The static insulin secretion in response to the high glucose concentration (16.7 mM) of the sedentary group at rest was lower than the sedentary group submitted to the acute exercise and the inverse was observed in relation to the trained groups. Physical training at the AT intensity improved the aerobic condition and altered insulin secretory pattern by pancreatic islets.

Serum S100b Levels In Triathletes After Different Types Of Exercise

The cerebral S100B protein has been used as a peripheral marker of central nervous system injuries. However, recent studies have shown that S100B protein also increases after physical exercise, yet these increases are not completely understood. Some authors have proposed that S100B increase during exercise is related to active secretion by skeletal muscle. PURPOSE: Investigate serum S100B levels in running versus bicycling exercise, establishing a relationship among S100B and myoglobin, a traditional blood marker for muscle damage. METHODS: 13 male triathletes presenting (mean±SD) age= 33.9 ± 6.0 years, body mass= 74.7±6.8 kg, height = 177.0±0.1 cm and body fat = 11.1±4.7% participated in this study. They randomly completed two sub maximal exercise protocols lasting 40 minutes each at anaerobic threshold intensity. The running exercise was performed in treadmill with no inclination (RUN). The bicycling exercise was done in the athlete's own bicycle using a cycle-simulator (CYC). During each protocol, blood samples were taken before (PRE) and immediately after (POST) exercise. Protocol and time comparisons were made using paired t-tests. The samples were analyzed for S100B and myoglobin (Mb). RESULTS: After treadmill protocol, S100B was increased (PRE=0.109±0.002 vs POST=0.113±0.005 μg/L, p<0.05) as well as Mb (PRE= 38.8±9.1 vs POST=88.7±24.1 ng/ml, p<0.05). In the bicycle test there was no increase after exercise for these two variables. Immediately after exercise serum values for S100B (RUN = 0.113±0.005 vs CYC = 0.109±0.001 μg/L) and Mb (RUN=88.7±24.1 vs CYC = 49.2±13.6 ng/ml, p<0.05) were statistically higher in RUN than in CYC. There was a significant correlation between S100B and myoglobin after RUN and CYC (r=0.59, p=0.03). CONCLUSIONS: Exercise that presents higher muscle damage (RUN) promoted an increase in serum S100B levels, while exercise in the same intensity/duration (CYC) with lesser muscle damage did not present a significant increase in S100B.

Intensity level for exercise training in fibromyalgia by using mathematical models

BackgroundIt has not been assessed before whether mathematical models described in the literature for prescriptions of exercise can be used for fibromyalgia syndrome patients. The objective of this paper was to determine how age-predicted heart rate formulas can be used with fibromyalgia syndrome populations as well as to find out which mathematical models are more accurate to control exercise intensity.MethodsA total of 60 women aged 18-65 years with fibromyalgia syndrome were included; 32 were randomized to walking training at anaerobic threshold. Age-predicted formulas to maximum heart rate ("220 minus age" and "208 minus 0.7 × age") were correlated with achieved maximum heart rate (HRMax) obtained by spiroergometry. Subsequently, six mathematical models using heart rate reserve (HRR) and age-predicted HRMax formulas were studied to estimate the intensity level of exercise training corresponding to heart rate at anaerobic threshold (HRAT) obtained by spiroergometry. Linear and nonlinear regression models were used for correlations and residues analysis for the adequacy of the models.ResultsAge-predicted HRMax and HRAT formulas had a good correlation with achieved heart rate obtained in spiroergometry (r = 0.642; p < 0.05). For exercise prescription in the anaerobic threshold intensity, the percentages were 52.2-60.6% HRR and 75.5-80.9% HRMax. Formulas using HRR and the achieved HRMax showed better correlation. Furthermore, the percentages of HRMax and HRR were significantly higher for the trained individuals (p < 0.05).ConclusionAge-predicted formulas can be used for estimating HRMax and for exercise prescriptions in women with fibromyalgia syndrome. Karnoven's formula using heart rate achieved in ergometric test showed a better correlation. For the prescription of exercises in the threshold intensity, 52% to 60% HRR or 75% to 80% HRMax must be used in sedentary women with fibromyalgia syndrome and these values are higher and must be corrected for trained patients.

The Comparisons of Heart Rate Variability and Perceived Exertion During Simulated Cycling with Various Viewing Devices

Sympathovagal modulation during immersion in a virtual environment is an important influence on human performance of a task. The aim of this study is to investigate sympathovagal modulation using heart rate variability and perceived exertion during exercise in a virtual reality (VR) environment. Sixteen young healthy volunteers were tested while using a stationary bicycle and maintained at an anaerobic threshold intensity for exercise sessions of approximately 10 min duration. Four randomized viewing alternatives were provided including desktop monitor, projector, head mounted device (HMD), and no simulation display. The “no simulation display” served as the control group. A quick ramp exercise test was conducted and maintained at an anaerobic threshold intensity for each session to evaluate power spectral density and rating of perceived exertion (RPE). The sampled heart rate data were rearranged by cubic spline interpolation into power spectrums spanning the ultra-low frequency (ULF) to high frequency (HF) range. A significant difference was found between the no-display and projector groups for total power (TP) and very low frequency (VLF) components. In particular, there was a significant difference when comparing HMD and no-display exercise RPE curves within 6 min of cycling and at the termination of the exercise. A significant difference was also achieved in projector vs. control group comparison at the termination of the exercise. Our results indicate that the use of HMD and the projected VR during cycling can reduce the TP and VLF power spectral density through a proposed decrease in the renin-angiotensin system, with the implication that this humoral effect may enable anaerobic exercise for longer durations through a reduction in sympathetic tone and subsequent increased blood flow to the muscles.

Effect of a single bout of moderate exercise on glucose uptake in type 2 diabetes mellitus

Hypoglycemia during exercise is a serious problem in diabetic patients during cardiac rehabilitation, whereas normal subjects rarely experience hypoglycemia. Inappropriate glucose uptake by working muscles may be responsible. However, the precise characteristics of glucose uptake during exercise have not been fully studied. We have investigated the effect of acute exercise on glucose uptake in diabetic patients. Nine type 2 diabetic patients (age, 57 ± 6 years; HbA1c, 7.7 ± 1.3%) performed exercise at an intensity of anaerobic threshold for 15 min. Glucose utility was determined using euglycemic hyperinsulinemic clamp technique. Glucose infusion rate (GIR) was calculated throughout the exercise and recovery session. Average GIR at rest was 3.4 ± 1.6 mg/(kg(BW)min). Fifteen minutes after starting exercise, it increased significantly (6.6 ± 2.4, p < 0.001). Thirty minutes after cessation of exercise, GIR decreased significantly (4.8 ± 1.9, p < 0.05) compared with peak value. Increase in GIR was greater as BMI or body fat ratio became greater (r=0.608 and 0.475). There was a weak correlation (r=0.344) between HbA1c and GIR improving ratio (GIR during exercise x 100/GIR at rest). Glucose uptake was revealed to augment significantly within 15 min after the commencement of exercise. This improvement was more obvious in patients with greater body weight, fat accumulation, and poorer diabetic control.

Identificação do limiar anaeróbio em indivíduos com diabetes tipo-2 sedentários e fisicamente ativos

Identification of the anaerobic threshold in sedentary and physically active individuals with type 2 diabetes Objective: To compare anaerobic threshold (AT) intensities determined from blood lactate, blood glucose and ventilatory responses among sedentary (SD) and physically active (AD) type-2 diabetics and active non-diabetics (AND), and to correlate metabolic, hemodynamic and body composition variables with the AT. Method: The SD (n= 9, 56.7 ± 11.9 years), AD (n= 9, 50.6 ± 12.7 years) and AND (n= 10, 48.1 ± 10.8 years) groups performed a cycle ergometer test with increases of 15 watts every three minutes until exhaustion. Heart rate, arterial pressure, perceived exertion, blood lactate, blood glucose and ventilatory variables were measured during the last 20 seconds of each incremental stage, to determine the lactate, ventilatory and glucose thresholds. Results: The AT intensities identified by the different methods did not differ from each other (p> 0.05). However, the absolute intensities were lower for SD than for the active groups (p< 0.05). No differences in intensity were found between the groups in relation to maximum oxygen consumption (%VO 2 peak) and maximum power (%Ppeak) at which the AT was observed. There was a significant correlation between AT and percentage fat (r= -0.52), and there was a trend towards correlation between AT and ambulatory blood glucose (r= -0.33). The hemodynamic variables did not show any correlations with AT. Conclusion: The AT was identified by means of the techniques studied, among type 2 diabetics and non-diabetics. Despite the differences between the groups with regard to absolute intensities (watts), diabetes did not appear to influence the relative intensities at which the AT was observed. The AT presented a correlation with body composition and a trend towards correlation with ambulatory blood glucose, thus suggesting that the AT is an important parameter in clinical assessments for such patients.

Abnormal response of left ventricular systolic function to submaximal exercise in post-partial left ventriculotomy patients

Patients with heart failure who have undergone partial left ventriculotomy improve resting left ventricular systolic function, but have limited functional capacity. We studied systolic and diastolic left ventricular function at rest and during submaximal exercise in patients with previous partial left ventriculotomy and in patients with heart failure who had not been operated, matched for maximal and submaximal exercise capacity. Nine patients with heart failure previously submitted to partial left ventriculotomy were compared with 9 patients with heart failure who had not been operated. All patients performed a cardiopulmonary exercise test with measurement of peak oxygen uptake and anaerobic threshold. Radionuclide left ventriculography was performed to analyze ejection fraction and peak filling rate at rest and during exercise at the intensity corresponding to the anaerobic threshold. Groups presented similar exercise capacity evaluated by peak oxygen uptake and at anaerobic threshold. Maximal heart rate was lower in the partial ventriculotomy group compared to the heart failure group (119 +/- 20 vs 149 +/- 21 bpm; P < 0.05). Ejection fraction at rest was higher in the partial ventriculotomy group as compared to the heart failure group (41 +/- 12 vs 32 +/- 9%; P < 0.0125); however, ejection fraction increased from rest to anaerobic threshold only in the heart failure group (partial ventriculotomy = 44 +/- 17%; P = non-significant vs rest; heart failure = 39 +/- 11%; P < 0.0125 vs rest; P < 0.0125 vs change in the partial ventriculotomy group). Peak filling rate was similar at rest and increased similarly in both groups at the anaerobic threshold intensity (partial ventriculotomy = 2.28 +/- 0.55 EDV/s; heart failure = 2.52 +/- 1.07 EDV/s; P < 0.0125; P > 0.05 vs change in partial ventriculotomy group). The abnormal responses demonstrated here may contribute to the limited exercise capacity of patients with partial left ventriculotomy despite the improvement in resting left ventricular systolic function.

COMPARISON OF PHASE II CARDIAC REHABILITATION PROGRAM OUTCOME IN WOMEN VERSUS MEN AFTER ACUTE MYOCARDIAL INFARCTION

Cardiovascular disease (CVD) ranks first among all disease categories in hospital discharges for women. However, research has focused on men while less is known about the disease in women. PURPOSE To compare the effect of gender difference on the rehabilitation outcome in patients with acute myocardial infarction. METHODS thirteen women (aged 66.2±4.2 years) were enrolled in an 8-week cardiac rehabilitation (CR) program after acute myocardial infarction. Another 39 men with matched age (66.0±3.7 years) and severity (number of embolismic vessels: 1.38±0.65 in women and 1.41±0.59 in men) were also enrolled and the two groups were compared. Both groups completed the exercise stress test and followed the identical cardiac rehabilitation program, including exercise training and patient education. Subjects were trained three times a week at the intensity of anaerobic threshold (AT). Exercise capacity was compared before CR, after CR and 6 months follow-up after the end of CR. RESULTS Two way ANOVA was used to compare the effect of difference in AT for gender effect (two levels: women versus men) and training effect with repeated measures on the second factor (three levels: before CR, after CR and 6 months after the end of CR). The results showed significant interaction between gender effect and training effect (p < 0.05). Simple effect shows AT in women continues to increase throughout phase III (0.74 W/kg, 0.82 W/kg, and 0.87 W/kg), while AT in men decreases after CR stops (0.89 W/kg, 1.06 W/kg, and 1.00 W/kg,). CONCLUSION 8-wks CR program benefits both men and women since AT significantly increases at the end phase II when compared to phase I. However, when comparing AT in phase III, women show continuous improvement in AT but men instead show decreased AT in phase III.