Bruce Protocol Treadmill Test Research Articles

Cardiorespiratory Fitness Decreases High-Sensitivity C-Reactive Protein and Improves Parameters of Metabolic Syndrome.

To evaluate the relationship between cardiorespiratory fitness (CRF), expressed as maximal oxygen uptake (ml.kg-1.min-1), metabolic syndrome (MetS), and high-sensitivity C-reactive protein (hs-CRP), a marker of systemic inflammation. The relationship between CRF, MetS, and hs-CRP was examined in a cohort of 173 men and women. CRF was evaluated using a Bruce protocol treadmill test and measured as estimated maximal oxygen uptake (VO2 max). Participants' physical activity status was self-reported. Plasma hs-CRP levels were measured using a standardized immunoassay, and the diagnostic criteria for MetS were based on guidelines established by the International Diabetes Federation (IDF). An inverse association was observed between hs-CRP levels and estimated VO2 max (p<0.01). Additionally, hs-CRP increased linearly with the number of MetS criteria present (p<0.01), while the estimated VO2 max decreased as the number of MetS criteria increased (p<0.01). Moreover, higher estimated VO2 max correlated with increased self-reported physical activity levels (p<0.01). Notably, participants engaging in two to three hours of exercise per week had hs-CRP levels ≤2.5 mg/L (p=0.018), considered a low-to-moderate risk range. Higher CRF, reflected by an estimated VO2 max, ≥45 ml/kg/min, is associated with lower hs-CRP levels and fewer MetS criteria. Additionally, regular physical activity, corresponding to higher VO2 max, appears to reduce systemic inflammation and ameliorate MetS risk factors. These findings support the mechanisms by which improved CRF and exercise may lower the risk of cardiovascular diseases (CVD) and type 2 diabetes (T2DM).

The Effect of Hypoxic Exercise Combined with Crocodile Blood Supplementation on Aerobic Capacity and Hematological Variables in Athletes

Study purpose. This study aimed to compare the effects of hypoxic exercise combined with crocodile blood supplementation on hematological and maximum oxygen consumption parameters in soccer players. Materials and methods. This study included 39 male soccer players aged 21.69 ± 1.98 years who were randomized to three groups. All groups performed the same training program, which comprised treadmill exercise at 70%–75% of maximum heart rate for 7 weeks with sessions of 30 min/day and 3 days per week. The first group was the control placebo group (CG, n = 13), the second group received one capsule per day (60 mg) of a freeze-dried crocodile blood supplement (SUP, n = 13), and the third group received the freeze-dried crocodile blood supplement and performed the training program under hypoxic conditions (H-SUP, n = 13, FiO2 = 16.3%). A hematological evaluation was conducted and maximal oxygen uptake (VO2max) was measured using the Bruce protocol treadmill test. Results. The H-SUP group demonstrated significantly higher erythropoietin (EPO) levels (14.40 ± 2.41 mIU/mL) compared to the SUP group (11.50 ± 2.08 mIU/mL) and CG (12.01 mIU/mL) after the intervention. From pre- to post-intervention, VO2max significantly increased in the H-SUP (Pre: 45.63 ± 4.75, Post: 49.33 ± 5.81) and SUP groups (Pre: 44.59 ± 4.75, Post: 47.30 ± 5.68) but not in the CG. Conclusions. This study reveals that a combination of freeze-dried crocodile blood supplementation and hypoxic exercise causes hematological alterations, particularly the activation of EPO secretion, and increases VO2max in soccer players.

Reliability of field- and laboratory-based assessments of health-related fitness in preschool-aged children.

Reliable measurements of health-related fitness-cardiorespiratory endurance, muscular endurance, muscular strength, body composition, and flexibility-are imperative for understanding and tracking health-related fitness from the preschool age. This study aimed to examine the test-retest reliability of field-based (i.e., sit and reach [standard and back-saver], standing long jump, grip strength); and laboratory-based (i.e., Bruce Protocol Treadmill Test, Wingate Anaerobic Test) assessments of health-related fitness in preschool aged children (4-5 years). Forty-two typically developing children participated in both assessment time points separated by 2-3 weeks. All fitness assessments were administered individually and repeated in the same order by the same assessor. Heteroscedasticity was examined for each parameter. Intraclass correlation coefficients were calculated to assess test-retest reliability. All parameters were homoscedastic. Test-retest reliability for the field-based tests and Bruce Protocol Treadmill Test parameters were moderate to good. Test-retest reliability for the Wingate Test parameters were good to excellent for maximum pedal rate, peak power, and peak power/kg; mean power and fatigue measured at 10 and 30 s demonstrated moderate to excellent test-retest reliability. The standard sit and reach, grip strength, and short-term muscle power from the Wingate test are reliable assessments of health-related fitness in preschool-aged children.

Peak substrate oxidation and peak oxygen consumption are diminished in individuals with mild cognitive impairment

The number of persons with Alzheimer’s Disease (AD) is projected to double within the coming decades, placing great emphasis on identifying accessible risk factors. Prior to AD, there is an important transitional phase, called mild cognitive impairment (MCI), where individuals first display objective declines in cognitive functioning. Growing evidence suggests that the risk factors of AD and MCI adversely affect mitochondrial function, presenting a potential measure that may be useful in risk stratification. Metabolic flexibility represents the capacity of the mitochondria to oxidize a variety of fuel substrates (i.e., carbohydrates and fatty acids), and can be assessed using a graded exercise test. Thus, metabolic flexibility may be a useful index of mitochondrial health that can be evaluated prior to the development of clinical AD. OBJECTIVE: To determine whether cardiorespiratory fitness and metabolic flexibility are attenuated in older adults with MCI in response to a graded exercise test. HYPOTHESIS: We hypothesized that individuals with MCI would have similar baseline, but reduced peak oxygen consumption (VO2peak), fat oxidation (FatOx), and carbohydrate oxidation (CHOOx) compared to healthy controls. METHODS: 22 older adults with MCI and 21 sedentary healthy controls (HCs) matched for both age and sex underwent a modified Bruce Protocol treadmill test to assess VO2peak. FatOx and CHOOx were calculated based on ventilatory equivalents using the equations: FatOx = 1.67VO2 - 1.70VCO2 [L/min] and CHOOx = 4.585VO2 - 3.2255VCO2 [L/min], respectively. Unpaired t-tests were conducted to determine whether baseline or peak oxygen consumption, FatOx, and CHOOx were different between groups. RESULTS: The MCI and the HC groups were similar in age (73.5 + 8.81 vs. 71.2 + 6.33, p=0.33) and BMI (26.2 + 4.92 vs. 26.8 + 5.16, p=0.70). Baseline FatOx (0.09 + 0.03 vs. 0.10 + 0.05 g/min, p=0.47) and CHOOx (0.51 + 0.17 vs. 0.59 + 0.21 g/min, p=0.23) were not different between the MCI and HC groups. Peak FatOx (0.31 + 0.13 vs. 0.39 + 0.10 g/min, p=0.018*), and peak CHOOx (1.89 + 0.41 vs. 2.18 + 0.49 g/min, p=0.047*) were lower in the MCI group relative to HCs. Additionally, the MCI group had a lower absolute (1.32 + 0.33 vs. 1.61 + 0.47 L/min, p=0.027*), and relative (22.0 + 5.0 vs. 19.1 + 5.30 mL/kg/min, p=0.070) VO2peak, although the latter was not statistically significant. CONCLUSION: Peak FatOx, CHOOx, and absolute VO2peak are diminished in older adults with MCI, which may suggest impaired whole body mitochondrial capacity and metabolic flexibility. However, future studies are necessary to determine the exact physiological and behavioral components to these observed reductions. Supported by NIH Grants R01 AG058853 and K01 AG054731 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

A New Approach to Noninvasive-Prolonged Fatigue Identification Based on Surface EMG Time-Frequency and Wavelet Features.

In sports, fatigue management is vital as adequate rest builds strength and enhances performance, whereas inadequate rest exposes the body to prolonged fatigue (PF) or also known as overtraining. This paper presents PF identification and classification based on surface electromyography (EMG) signals. An experiment was performed on twenty participants to investigate the behaviour of surface EMG during the inception of PF. PF symptoms were induced in accord with a five-day Bruce Protocol treadmill test on four lower extremity muscles: the biceps femoris (BF), rectus femoris (RF), vastus medialis (VM), and vastus lateralis (VL). The results demonstrate that the experiment successfully induces soreness, unexplained lethargy, and performance decrement and also indicate that the progression of PF can be observed based on changes in frequency features (ΔF med and ΔF mean) and time features (ΔRMS and ΔMAV) of surface EMG. This study also demonstrates the ability of wavelet index features in PF identification. Using a naïve Bayes (NB) classifier exhibits the highest accuracy based on time and frequency features with 98% in distinguishing PF on RF, 94% on BF, 9% on VL, and 97% on VM. Thus, this study has positively indicated that surface EMG can be used in identifying the inception of PF. The implication of the findings is significant in sports to prevent a greater risk of PF.

The effects of cloth face masks on cardiorespiratory responses and VO2 during maximal incremental running protocol among apparently healthy men

We aimed to determine the effects of wearing a cloth face mask on cardiorespiratory response, peak oxygen uptake (Vo2), respiratory muscle effort, and exercise tolerance during incremental exercise. The study had a randomized crossover design: 11 apparently healthy young men performed the Bruce protocol treadmill test in two conditions, wearing a cloth face mask (CFM) and without CFM (CON), in random order. Minute ventilation and oxygen uptake were measured using a mass spectrometry metabolic analyzer; cardiac output (CO) was measured using an impedance CO monitor; and mouth pressure (Pm) was measured and calculated as an integral Pm to assess respiratory muscle effort. Maximal minute ventilation was 13.4 ± 10.7% lower in the CFM condition than in the CON condition (P < 0.001). The peak Vo2 (52.4 ± 5.6 and 55.0 ± 5.1 mL/kg/min in CFM and CON, respectively) and CO were not significantly different between the two conditions. However, the integral value of Pm was significantly higher (P = 0.02), and the running time to exhaustion was 2.6 ± 3.2% lower (P = 0.02) in the CFM condition than in the CON condition. Our results suggest that wearing a cloth face mask increased respiratory muscle effort and decreased ventilatory volume in healthy young men; however, Vo2 remained unchanged. Exercise tolerance also decreased slightly.

Factors associated with the intermediate probability of heart failure with preserved ejection fraction on the H&lt;sub&gt;2&lt;/sub&gt;FPEF score in asymptomatic patients in rotation work conditions in the Arctic

Aim. To study the factors associated with the intermediate probability of heart failure (HF) with preserved ejection fraction (HFpEF) according to the H2FPEF score (Heavy; Hypertensive; Atrial Fibrillation; Pulmonary Hypertension; Elder; Filling Pressure) in asymptomatic patients in rotation work conditions in the Arctic.Material and methods. In the polar village of Yamburg (68° 21’ 40” northern latitude), 100 men and 80 women with grade 1, 2 hypertension and normotensive persons were examined on the basis of the Medical Unit of OOO Gazprom Dobycha Yamburg. All patients underwent echocardiography using generally accepted methods of imaging and data processing, according to European Society of Echocardiography guidelines. To calculate the probability of HFpEF, the H2FPEF score was used. The Bruce protocol treadmill test was performed. The SF-36 (Health Status Survey) questionnaire for assessment of life quality was used.Results. Group 1 included 95 male and female patients with a low probability of HF (H2FPEF score — 0-1), group 2 — 85 patients of both sexes with an intermediate probability of HF (H2FPEF score — 2-5). Group 2 patients were older (p=0,038), worked longer on a shift (p=0,0143), and had higher ambulatory systolic (p=0,0001) and diastolic blood pressure (p=0,0013) with a higher body mass index (BMI) (p=0,0001). Based on the odds ratio (OR) analysis, the factor most strongly influencing the intermediate probability of HFpEF was BMI (OR=1,261, 95% confidence interval (CI): 1,140-1,393). SF-36 questionnaire revealed intergroup differences only on the role functioning scale (p=0,013) with lower values in group 2. In the logistic regression model, dyspnea during the treadmill test occupied a leading position as follows: OR=8,952; 95% CI: 3,454-15,197 (p&lt;0,0001). The second place was taken by inotropic reserve value (OR=1,020; 95% CI: 1,006-1,035 (p=0,005), which was higher in group 2 and was regarded as one of the compensatory mechanisms for adapting to stress. In the group 2, echocardiography revealed significant differences in terms of left ventricular (LV) myocardial mass (p=0,0002), LV internal area (p=0,0002), isovolumic relaxation time (p=0,003), and ratio of transmitral diastolic flow rate to mean mitral annulus velocity (p=0,0001), which indirectly indicates the presence of LV diastolic dysfunction.Conclusion. There are following factors associated with H2FPEF intermediate probability of HFpEF in asymptomatic patients on shift in the Arctic: BMI, length of shift, dyspnea and an increase in inotropic reserve during exercise due to a decrease in adaptive potential, impaired LV diastolic function. Initiating management strategies that target identified factors in patients with asymptomatic HF may slow symptomatic disease progression in shift workers in the Arctic region.

A Comparison of the Effects of Resistance and Endurance Training Protocols on Serum Irisin Level and Alkaline Phosphatase Activity in Sedentary Obese Women

Abstract Introduction. Studies have revealed that the anabolic effect of irisin on bone is mediated by an increase in alkaline phosphatase. However, few studies have investigated the interactive effect of irisin on alkaline phosphatase after exercise training. Therefore, the present study aimed to compare the impact of endurance and resistance training protocols on serum irisin concentration and total alkaline phosphatase activity in sedentary obese women. Material and methods. Forty-five sedentary obese women (age: 48.96 ± 5.2 years, body mass index 32.24 ± 3.76 kg/m2) were randomly assigned to control, endurance, and resistance groups. Endurance (45 to 75 minutes at an intensity corresponding to 50 to 80% of heart rate reserve) and resistance exercise training (3 sets, 10-15 repetitions at an intensity corresponding to 50 to 65% of one-repetition maximum) were conducted for 8 weeks, 3 days per week. Maximal oxygen consumption (VO2max) was estimated using the modified Bruce protocol treadmill test. Fasting blood samples were taken before the first and 48-hr after the last exercise training sessions. The serum concentrations of irisin and total alkaline phosphatase activity were measured using the sandwich ELISA method and photo-metric method, respectively. Results. Both endurance and resistance exercise training protocols caused a significant reduction in BMI and BFP of obese women. In contrast, VO2max significantly increased after both exercise training protocols. However, neither endurance nor resistance training protocols had a significant impact on the serum concentrations of irisin and total alkaline phosphatase activity. No significant inter-group differences were observed between the subjects’ BMI, BFP, VO2max, total alkaline phosphatase, and irisin at the end of protocols. Conclusions. The finding of the current study revealed that neither of the training protocols had a significant impact on bone anabolic parameters. However, performing these types of exercise is suggested for weight management in obese women.

Perceptions of Ability Mediate the Effect of Motor Coordination on Aerobic and Musculoskeletal Exercise Performance in Young Children at Risk for Developmental Coordination Disorder.

This study examined the effects of perceptions of motor abilities on aerobic and musculoskeletal exercise performance in young children at risk for developmental coordination disorder (rDCD). The participants (N = 539) were part of a larger cohort study, the Coordination and Activity Tracking in Children (CATCH) study. The Movement Assessment Battery for Children (2nd Edition) was used to determine rDCD children. Perceptions of motor abilities were measured by the Perceived Efficacy and Goals Setting system. Aerobic exercise performance was measured using the Bruce Protocol treadmill test, and musculoskeletal exercise performance was assessed using the standing long jump and the Wingate Anaerobic test. The rDCD children reported lower Perceived Efficacy and Goals Setting scores and performed worse on all exercise performance measures. Perceptions of ability also mediated the relationship between developmental coordination disorder and each exercise performance test. It is concerning that children with low motor coordination report lower perceptions of ability even at a very young age.

Salivary Antioxidants Status Following Progressive Aerobic Exercise: What Are the Differences between Waterpipe Smokers and Non-Smokers?

Waterpipe tobacco (WPT) smoking is a public health problem with similar or even stronger effects than cigarette smoking. Although it appears to be associated with extensive oxidative stress, there is a limited number of studies on the oxidative effects of WPT smoking in stressful conditions. We, therefore, compared the responses of salivary flow rate (SFR), uric acid (UA) concentration, and peroxidase (POX) and 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) activities between WPT smokers and non-smokers following a bout of exhaustive aerobic exercise (AE). Twenty-three sedentary young women (age: 22.95 ± 2.83 years) participated in this study, including 11 smokers (7.00 ± 1.41 uses/week) and 12 non-smokers. All participants were required to perform the Bruce protocol treadmill test at an initial gradient of 10% at 1.7 mph, with increases of these parameters every 3 min until exhaustion. Unstimulated saliva samples were collected before, immediately after, and 1 hour after AE. WPT smokers showed lower SFR compared with non-smokers at all time points (p < 0.05). In comparison to WPT smokers, a larger increase in POX activity (approximately 23% vs. 14%; p = 0.009) and a smaller decline in DPPH activity (approximately −8% vs. −15%; p = 0.004) were found in non-smokers compared with WPT smokers. While these changes were slowly compensated within 1 hour after exhaustion, the activity of both markers was different from the pre-exercise values (p < 0.001). There was also a trend for UA concentration in non-smokers to be higher during the recovery period, with no significant difference between the groups (p > 0.05). It seems that WPT smoking is associated with negative effects on important human antioxidants and a diminished antioxidative response following acute exercise.

A New Threshold Estimation Method of SEMG Wavelet De-noising for Prolonged Fatigue Identification

In sports training, fatigue management is very important to avoid muscle injury and chronic fatigue syndrome. It occurs due to untreated normal fatigue (NF) which leads to a higher level of fatigue. This paper refers to the higher level of fatigue condition as prolonged fatigue (PF). Fatigue can be identified based on musculoskeletal, physiological, psychological, immunological and endocrinal system condition. Presently, musculoskeletal or muscle condition can be accessed quantitatively based on an invasive technique known as biopsies. It is accurate to evaluate muscle condition, but not suitable for frequent measurements. The non-invasive method used through self-evaluation tools such as questionnaire is not a quantitative measurement and sometimes is difficult to quantify. There are other non-invasive methods to evaluate muscle condition known as surface electromyography (SEMG). Before this, SEMG were only widely used to classify between non-fatigue and NF conditions. However, NF prediction might not be accurate and suitable to be used on athletes since they are required to undergo high-intensive training every day and this involves PF condition. Recently, SEMG signals characteristics found out to be able to evaluate ionic concentration changes in the muscle due to intensive training. The signals characteristics are different compared to NF identification. Therefore, high quality SEMG plays an important role in PF detection to avoid misinterpretation. In this study, twenty healthy participants were recruited and performed five consecutive days of intensive training to induce PF symptoms. The training was based on Bruce Protocol treadmill test and SEMG data were collected from the participants’ rectus femoris muscle. This paper pre-processed SEMG signals using Stationary Wavelet Transform (SWT) ‘db’ 45 with different threshold estimation techniques of de-noising such as RigRSURE, HeurSURE, minimax, universal threshold and a new estimation of threshold method. The new method able to overcome the limitation of conventional methods which estimate threshold based on statistical principles. Most importantly, the new method can preserve significant SEMG information, remove corner frequency and mitigate baseline noises. The performance of conventional and propose methods can then be evaluated based on PF classification performance. The de-noised signals extracted based on time, frequency and time-frequency features. Naive Bayes classification results using time and frequency features indicate that the new estimation of threshold method with time and frequency features have the highest accuracy (98%), compared to RigRSURE (85%), HuerSURE (68%), Universal Threshold (74%) and minimax (76%) in PF identification.

The effect of 2 walking programs on aerobic fitness, body composition, and physical activity in sedentary office employees.

PurposeThe present study examined changes in body composition, maximum oxygen uptake, and physical activity in sedentary office employees prescribed with two different walking programs during a 10-week intervention.Methods68 sedentary employees were randomly assigned to one of three groups: multiple bouts of walking (n = 24 (5 male, 19 female) Age = 46±9, BMI = 30.5±5.78 kg/m2), continuous walking (n = 22 (6 male, 16 female) Age = 48±9, BMI = 30.6±6.2 kg/m2) and the control group (n = 22 (5 male, 17 female) Age = 42±10, BMI = 27.5±5.23 kg/m2). Dual-energy X-ray absorptiometry (iDXA) assessed body composition and a Bruce protocol treadmill test assessed aerobic fitness at baseline and week 11. At baseline, week 6 and week 11 a waist worn accelerometer measured physical activity and sedentary behavior. Physical activity was measured throughout the program with a wrist worn accelerometer.ResultsThe results from the mixed-design ANOVA show that fat mass (p < .000) and fat percentage (p < .000) decreased for all three groups as a main effect of time. Sedentary behavior did not change (p>0.05) for all three groups. Moderate intensity physical activity increased significantly from pre-test to week 6 (p<0.05), then decreased from week 6 to post-test (p<0.05), with no significant changes observed from pre-test to post-test (p>0.05) for all groups. No changes in VO2 were observed (p>0.05) for all groups.ConclusionsContinuous or intermittent walking activity produce similar benefits on body weight, fat mass and body fat percentage in sedentary employees. Meanwhile, intermittent walking allowed these sedentary employees to increase lean mass and fat free mass. Intermittent walking could provide at least similar benefits on body composition compared to a continuous walking program.

Validation of the Polar Fitness Test

Aerobic capacity testing can be beneficial to coaches, physical educators, and trainers in the process of designing aerobic training programs. However, testing in a laboratory can be costly. Polar heart rate monitors provide a fitness test that estimates aerobic capacity without having to use expensive equipment. The purpose of this study was to determine the efficacy of the Polar fitness test in comparison to the laboratory test. Eighteen college age students completed the Polar fitness test along with a laboratory test for aerobic capacity. The laboratory test consisted of a maximal Bruce protocol treadmill test while the subject was connected to a metabolic cart. The study found that the Polar fitness test provides results that are not statistically different from the metabolic cart results (t = 1.681, p = 0.111). Additionally, the 2 tests were strongly correlated (r = 0.545, p = 0.019). This indicates that the Polar fitness test may be an appropriate means of aerobic capacity testing for those not needing the accuracy of expensive laboratory equipment.

Features selection for Bayes classification of prolonged fatigue on rectus femoris muscle.

Sports training is very important to athletes in improving and maintaining their performances. It commonly involves high intensity exercise and requires longer time for fatigue to recover, compares to normal activity. During training, adequate rest is essential to allow recuperation and build body strength. Unfortunately, inadequate rest exposes the body to prolonged fatigue (PF). Hence, this condition needs to be managed accordingly to avoid chronic fatigue syndrome. Recent findings indicate that there are strong characteristics on surface EMG under PF conditions. Currently, the assessment is limited to glycogen breakdown, the existence of lactate and soreness. In this study, twenty participants were recruited to perform five days intensive training (IT) to induce more PF signs. The IT conducted was based on Bruce Protocol treadmill test. It was discovered that the IT successfully induces soreness, unexplained lethargy and performance decrement. Surface EMG were collected from rectus femoris muscle during daily pre and post treadmill tests. Four features were extracted from the surface EMG; mean frequency (Fmean), median frequency (Fmed), root mean square (RMS) and mean absolute value (MAV). The results indicated that all features during post exercise had greater value under PF condition and it was significant at P<;0.05. The features then were classified in accordance to Bayes. The results also showed that Fmed and MAV features offered good performance with 83.1% accuracy, 84.6% specificity and 80% of precision.

Assessment of endpoint criteria and perceived barriers during maximal cardiorespiratory fitness testing among pregnant women.

A plateau in volume of oxygen consumption (VO2) is the primary indicator for determining if an individual has reached their maximal aerobic capacity. However, secondary criteria can also be used to identify maximal effort (i.e. lactate level, rating of perceived exertion [RPE], percent of age-predicted maximal heart rate [HR] and respiratory exchange ratio [RER]). Age and gender-specific secondary criteria have been developed for the general population, but no secondary criteria have been established for pregnant women. The primary purpose of this study was to analyze secondary endpoint criteria during VO2max testing among pregnant women. A secondary purpose was to identify emotional and physical barriers pregnant women have that may prevent them from reaching maximal effort. Twenty-five pregnant women (age= 30.0±3.6 years; gestation age= 22.1±1.4 weeks, pre-pregnancy BMI= 23.68±4.04 kg/m2) participated. Each participant completed a Bruce protocol treadmill test and maximal HR, RER, lactate, and RPE were assessed and compared to standards. Barriers were assessed immediately postexercise via open-ended questions. The mean VO2max was 32.9±8.8 mL/kg/min. Mean RPEmax was 17.6±1.8 versus the standard of RPE≥17 (P=0.12). Percent of age-predicted HRmax was 88.0±6.8% versus the standard of ≥95% (P<0.001). Immediate postexercise lactate was 6.8±2.4mM versus the standard of ≥8 mM (P=0.03). Maximal RER was 1.2±0.2 versus the standard of RERmax ≥1.1 (P=0.08). Our data provide preliminary evidence that secondary criteria may need to be adjusted for pregnant women. Additionally, physical and emotional barriers may be enhanced by pregnancy (e.g. pain, discomfort, anxiety, health concerns), and may limit the performance of pregnant women during maximal exercise.

Trend of Endurance Level Among Healthy Inner-City Children and Adolescents Over Three Decades.

The aim of this study was to understand how endurance time, a proxy for physical fitness, has changed in healthy inner-city children and adolescents in the past three decades. This was a retrospective cross-sectional study. This study used exercise stress test in a laboratory of an inner-city teaching hospital. We reviewed all consecutive healthy children and adolescents who underwent an exercise Bruce protocol treadmill test from 1983 to 2010. The study population was divided into five groups of 5-year intervals based on the year of testing. Temporal trend in endurance time was analyzed, adjusting for gender, ethnicity, age, and body mass index (BMI). We analyzed the records of 435 healthy children and adolescents (mean age 12.6±3.2years, 57% males).There was a significant difference in the mean endurance time between children grouped in 5-year intervals (P<0.001) with a significant downward trend in endurance time over the years (P<0.001), especially after 2001. In contrast, there was no statistically significant change in the mean BMI between children grouped in 5-year intervals (P=0.205). Multivariate linear regression model demonstrated that the date of testing was independently predictive of endurance time, adjusting for age, gender, BMI, and ethnicity (P<0.001). Gender was the strongest independent predictor of endurance time, followed by age, BMI, and ethnicity. There is a downward trend in endurance time over the 27-year period among inner-city children and adolescents. Temporal decline in endurance time was independent of factors known to affect this parameter, such as age, gender, BMI, and ethnicity. Factors such as deconditioning due to sedentary lifestyle and lack of motivation to endure on the treadmill among later generations may have played a role in such decline.

Test Preference and its Relationship to Performance during Maximal Aerobic Exercise Testing

Maximal aerobic capacity (VO2max) is a strong variable in predicting risk of death from all-cause mortality as well as performance in many endurance sports. Proper test selection is important, and test preference may affect the results of VO2max testing. PURPOSE: To compare the preferred test method between three different VO2max tests and determine the relationship to performance. METHODS: 13 active subjects (8 men, 5 women; age 24±3 yrs) volunteered to participate in this study. All underwent three tests including: a standard Bruce protocol treadmill test followed by, in random order, a self-paced maximal VO2max test (SPV) on a cycle ergometer (CE SPV) and a treadmill (TM SPV). The SPVs were ten minutes long with intensity increasing every two minutes based on the 6-20 Rating of Perceived Exertion (RPE) scale, and included RPE values of 11,13,15,17 & 20. With the SPVs, subjects controlled the work rate to maintain the prescribed RPE. After the last test, subjects were immediately asked which test they preferred of the three, without further instruction. A chi-square goodness of fit was performed to determine if the tests were equally preferred and a chi-square test of independence was used to examine the relationship between preference and performance. RESULTS: Of the 13 subjects, five preferred the TM SPV (38%), six preferred the CE SPV (46%), and two preferred the Bruce protocol treadmill test (16%). Preference was equally distributed (X2=2.000, p=.368). Eight of the subjects (62%) preferred the test they performed their best on while five did not (38%). The relationship between test preference and performance was not significant (X2=8.790, p=.067). CONCLUSIONS: In this study, “preference” was not defined for the subjects. Some may have chosen their preferred test based on which one they thought they would perform best. These tests are maximal and thus subjects usually discontinue their efforts due to signals of overall or peripheral discomfort. The preferred test may have been chosen based solely on the level of discomfort experienced. Regardless, the results suggest that test preference may not affect performance during VO2max testing. Future studies should seek to examine how subjects define “preference” and if it could be used to choose the most appropriate protocol.

Cardiovascular and Metabolic Responses to Vinyasa Yoga and Paced Surya Namaskar B

Objectives: The purpose of this study is to assess cardiovascular response to a thirty-minute continuous and uniformly paced session of Surya Namaskar B. The metabolic response to the yoga protocol is compared to the maximum cardiovascular response assessed utilizing a Bruce Protocol treadmill test to determine whether or not the a vinyasa flow yoga practice, including frequent paced Surya Namaskar B, meets the guidelines for moderate intensity activity as outlined by the American College of Sports Medicine (ACSM). Methods: Four healthy men and women (37 - 62 years) who have practiced vinyasa yoga for at least six months participated in the study. Participants completed a Bruce Protocol treadmill test to assess maximum cardiovascular and metabolic response. In a subsequent session, participants completed thirty minutes of a paced Surya Namaskar B yoga protocol. Results: Participants exhibited an average 50% or more of their VO2 max and between 5-8 METS during the course of the thirty-minute yoga protocol. Conclusion: The practice of Surya Namaskar B, paced at approximately one sequence completed over 45 seconds, can elicit a moderate intensity cardiovascular response and meets the guidelines of moderate intensity activity.

Amplitude and frequency changes in surface EMG of biceps femoris during five days Bruce Protocol treadmill test.

Electromyography (EMG) is one of the indirect tools in indexing fatigue. Fatigue can be detected when there are changes on amplitude and frequency. However, various outcomes from literature make researchers conclude that EMG is not a reliable tool to measure fatigue. This paper investigates EMG behavior of biceps femoris in median frequency and mean absolute value during five days of Bruce Protocol treadmill test. Before that, surface EMG signals are filtered using band pass filter cut-off at 20-500Hz and are de-noised using db45 1-decimated wavelet transform. Five participants achieved more than 85% of their maximal heart rate during the running activity. The authors also consider other markers of fatigue such as performance, muscle soreness and lethargy as indicators to adaptation and maladaptation conditions. Result shows that turning points of median frequency and mean absolute value are very significant in indexing fatigue and indicators to adaptation of resistive training.

Menstrual Dysfunction, Hypoestrogenism, And Cardiac Parameters In Young Endurance Runners

PURPOSE: Menstrual dysfunction is common among endurance runners and may impact cardiovascular responses to exercise. The objective of this study was to examine the relationships among menstrual status, circulating levels of steroid hormones, cardiovascular function, and endurance performance in a group of female endurance athletes. METHODS: College-aged (18-22 yrs) female endurance distance runners reporting a history of eumenorrhea (EAs, n=11) or menstrual dysfunction (MDAs, n=9) performed a modified Bruce Protocol Treadmill Test. Salivary estradiol, testosterone, and cortisol levels, circulating lactic acid levels, and ECG data were collected pre- and post-run. Heart rate, VO2max, time to exhaustion, and rate of perceived exhaustion were measured pre-, during, and post-run. RESULTS: Athletes reporting menstrual dysfunction had significantly lower resting estradiol levels and higher testosterone levels than EAs, although these groups did not differ in training regimen, BMI, or body fat %. MDAs had significantly lower heart rates from prolonged ST intervals before, during and after the treadmill test. There were no differences in time to exhaustion, rate of perceived effort or VO2max between groups. CONCLUSION: Lower estradiol levels link neuroendocrine reproductive dysfunction with altered cardiovascular responses to training in female endurance athletes, though do not appear to influence submaximal performance. We propose that depressed heart rate and hypoestrogenism heart rates in young female athletes could aid in the early identification of the “athlete triad” and may indicated heightened risk for future cardiovascular disease.