Graded Treadmill Exercise Test Research Articles

Sympathetic Activity Assessed during Exercise Recovery in Young Obese Females

To evaluate differences in sympathetic activity, as assessed by an exercise recovery index (ERI; heart rate/oxygen consumption [VO2] plateau), between black and white obese female adolescents. An additional aim was to determine the association of ERI with insulin resistance (homeostasis model assessment of insulin resistance [HOMA-IR]), cardiovascular fitness per fat-free mass (VO2 per fat-free mass), systolic blood pressure (SBP), and percent body fat (%FAT) in both black and white obese adolescents. Sixty-one females volunteered to participate in this study. HOMA-IR, SBP, and %FAT were assessed during resting conditions in black (n = 49, 13.7 ± 1.6 years, 38.1 ± 6.1 kg/m(2)) and white (n = 12, 13.3 ± 2.2 years, 34.3 ± 4.9 kg/m(2)) obese adolescents. An ERI was calculated during a 5-minute passive recovery period immediately following a graded treadmill exercise test to exhaustion. The ERI was significantly greater in black compared with white obese adolescent females (29.8 ± 6.4 vs 24.1 ± 3.1 bpm·mLO2(-1)·min(-1), P = .004). Using multiple linear regression modeling, there was a significant independent association between ERI and VO2 per fat-free mass (r = -0.310, P = .027) and %FAT (r = 0.326, P = .020) in black obese adolescents after controlling for HOMA-IR and SBP. These results suggest that black obese adolescent females have greater sympathetic activity, as assessed by an ERI, than white obese adolescent females. These findings support the need for weight management efforts aimed at both reducing %FAT and improving fitness in obese adolescents, specifically black females. Registered with Clinicaltrials.gov: NCT00562293.

Peripheral Adaptation to Vigorous Aerobic Exercise in Women with Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a progressive pulmonary vascular disease of unknown etiology which causes a worsening ventilation-perfusion mismatch leading to activity-limiting dyspnea and physical inactivity. Recent studies indicate that aerobic exercise training (AET) improves physical function and health-related quality of life in populations with PAH, yet little is known about the mechanisms responsible for adaptations to AET. PURPOSE: To examine changes in peripheral muscle oxygen use after 10 weeks of vigorous AET in a population with PAH. METHODS: Twenty-four women with WHO Group I PAH were randomly assigned to receive either 10 weeks of AET or 10 weeks of education lectures (EDU). The AET consisted of treadmill walking thrice weekly for 30-45 minutes each session, with treadmill speed and inclination continuously adjusted to maintain subjects’ heart rates between 70 and 80% of heart rate reserve. Graded treadmill exercise tests (GXT) were performed on all subjects before and after the 10-week intervention period. Metabolic gases were collected and cardiac output (CO) was measured via impedance electrocardiography. Muscle tissue oxygen use was measured during both GXTs using near-infrared spectroscopy with the optodes placed over the right lateral belly of the gastrocnemius. RESULTS: Eleven women were assigned to the AET group (54±11 yrs, BMI=30±7 kg/m2; mean±SD) and 13 to the EDU group (56±9 yrs, BMI=32±7 kg/m2). The AET group improved GXT duration by 121±75 sec (p=0.001) with no significant change in the EDU group. Significant differences were observed between the groups for amplitude changes during GXT for oxyhemoglobin (O2Hb) (AET: -1.61±2.82 vs. EDU: 1.1±3.41 a.u., p=0.048) and hemoglobin difference (HbDiff) levels (-3.18±4.93 vs. 0.82±4.45 a.u., p=0.048). No significant changes were observed between groups for deoxyhemoglobin, total hemoglobin, or cardiac output. CONCLUSIONS: Ten weeks of AET improved physical performance without improving CO. Improvements in O2Hb suggest more oxygen availability within the muscle, and decreased HbDiff indicates more oxygen reserve was used after AET. These results suggest that peripheral rather than central adaptations may play a larger role in cardiorespiratory fitness improvements observed with AET in patients with PAH. Funding NIH/IRP 1 Z01 CL06006802.

Oxygen Uptake At Criterion RPE In Trained And Untrained Females Following Exercise And Memory Anchoring

Exercise and memory anchoring provides a definitive anchoring procedure for linking perceptions of effort to variable intensities of physical exertion. However, it is unclear if relative intensity at a given RPE would remain consistent in individuals of different training status. PURPOSE: The current investigation compared percent of maximal oxygen uptake in recreationally trained (RT) versus untrained (UT) adult females at selected, criterion RPE during maximal, graded, treadmill exercise following exercise and memory anchoring to the Borg 15-category scale. METHODS: The RT (n = 8) group (21.8± 2.0 yrs.) and the UT (n = 3) group (18.0 ± 0.0 yrs.) each received anchoring instructions during a maximal, graded treadmill exercise test at an initial session. The low anchor was assigned a seven and the high anchor was assigned a 19 on the scale. At a second session, memory anchoring instructions were provided prior to a GXT during which RPE was recorded following each stage. Linear regression with RPE as the independent variable and oxygen consumption as the dependent variable was used to calculate percent VO2max for each criterion RPE (7, 9, 11, 13, 15 17, and 19). An independent samples t-test was used to compare percent VO2max between RT and UT at each criterion RPE. RESULTS: As expected, VO2max was higher for the RT than the UT. All other descriptive variables were similar between groups. Relative oxygen uptake at each criterion RPE was also similar. CONCLUSION: Pre-exercise exercise and memory anchoring yielded similar relative VO2 for young adult females independent of training status. It appears that exposure to the high and low anchors during the anchoring procedure is sufficient to guide exercise intensity during a maximal, graded, treadmill exercise test for this population. The current findings further validate Borg’s assumption for the application of a category scale in that the perceptual range may be set equal for all individuals as percent VO2max was similar between young, adult women of varying training status.

Physiological Profiles And Training Demands In High-level Female Collegiate Dancers

Little is known about the physical status of high level dancers despite the physical demands placed upon them, which include explosive movements, quick changes in direction, callisthenic movements, and weight bearing interactions with others. Through the development of a physiological profile, more can be understood about the training status of these performers. PURPOSE: To establish a physiological profile of high-level female collegiate dancers through laboratory-based testing and monitor typical training-load associated with their classes. METHODS: College aged female dancers (N=17; Mweight= 59.8 ± 6.6 kg; Mage=19.9± 1.3 yrs ; Mheight=1.6 ± 0.1m) enrolled in a premier university performing arts program were tested over a two-day span to develop a physiological profile. Day 1 consisted of body composition assessment via BODPOD as well as maximal treadmill graded exercise test (GXT) to assess VO2max and ventilatory threshold (VT) via direct gas exchange. Day 2 consisted of vertical jump (VJ) to assess power and a Wingate Anaerobic Test (WAnT) on a cycle ergometer with a load set at 7.5% body mass to assess anaerobic power. Following testing, two classes were monitored for training intensity and energy expenditure using the Polar Team2 Pro System. Dancers were monitored during two typical ballet classes and modern dance classes. RESULTS: The dancers tested had an average body fat percentage of 24.1 ± 4.2 %, and a lean body mass of 46.8± 8.5 kg. The average VO2max was 42.9 ±4.27 (ml O2/kg/min)) with a VT of 76.1 ± 6.5 % of VO2max. The power output from the WAnT was 518.9 ± 177.26 W. Dancers had an average training load of 41.3 ± 17.4 for ballet and 46.3 ± 26.8 for modern dance while expending 400 ± 116.2 kcal and 421.5 ± 149.8 kcal respectively. Approximately 1.3 ± 2.7% of time in ballet and 3.8 ± 7.8 % of time in modern dance was spent at an intensity at or above VT. CONCLUSION: The dancers had a physiological profile that was notably below average compared to female Division I power endurance athletes, with a higher body fat percentage and lower aerobic and anaerobic capacity. These results may shed light on the high injury rate often seen in this population. The low training loads during the typical class suggest that supplemental conditioning would likely be necessary and beneficial both for reducing injury and improving performance.

Physical Activity is Decreased in Veterans with Non-Dialysis Chronic Kidney Disease

Chronic kidney disease (CKD) is the progressive deterioration of the kidney’s capacity to eliminate fluid and nitrogenous waste from the body. CKD is associated with diminished physical function and performance, slower walking speed, and greater risk of frailty. We hypothesized that older Veterans with non-dialysis CKD have lower levels of physical activity compared to age matched non-CKD hypertensive controls (HTN) and that low physical activity would be associated with worse renal function and physical function. PURPOSE: 1) Compare the physical activity (PA) levels of Veterans with non-dialysis CKD versus HTN controls; 2) Evaluate the association between renal functional and PA; 3) Evaluate the association of PA vs functional capacity. METHODS: 54 CKD and 32 HTN Veterans of comparable age (69 ± 6 vs 68 ± 7, p = 0.63) and BMI (30.9 ± 6.2 vs 29.9 ± 4.8 p = 0.43) had estimated glomerular filtration rate (eGFR) measured using the Modification of Diet in Renal Disease (MDRD) equation. eGFR between the CKD and HTN was 43.9 ± 14.4 vs 81.7 ± 19.6 (p < 0.001), respectively. Five days of physical activity were measured using a step activity monitor. Peak VO2 (ml/kg/min) was measured during a progressive graded exercise treadmill test to exhaustion. Group differences were analyzed by Student’s t-tests, and relationships were analyzed using Linear Regression. Data are mean ± standard deviation. RESULTS: The average steps walked per day were 34% lower among CKD patients compared to hypertensive controls (3359 ± 1832 vs 4410 ± 1645, p < 0.001). Lower eGFR was significantly associated with both fewer average steps per day (r = 0.36, p < 0.001) and a greater percentage of the day inactive (r = 0.35, p < 0.001). Veterans with less average steps per day have a lower functional capacity (r = 0.55, p < 0.001). CONCLUSIONS: Veterans with CKD have significantly lower physical activity and functional capacity compared to non-CKD hypertensive controls. Lower renal function is significantly associated with reduced physical activity and lower functional capacity. Low levels of habitual physical activity negatively affect physical fitness and function, and overtime may contribute to increased risk of morbidity and mortality and decreases in quality of life. Supported by the Department of Veterans Affairs Merit Award.

Short-term Heart Rate Variability And Its Correlation With Acute Maximal Graded Exercise In Healthy Adults

The influence of short-term heart rate variability (HRV) on acute maximal graded exercise performance is not clearly understood and there are considerable discrepancies in the literature regarding the same. PURPOSE: To investigate the correlation if any, between the short-term HRV parameters and the acute maximal graded treadmill exercise parameters in healthy adult volunteers. METHODS: Designed as a cross-sectional study, consecutive, consenting healthy adult volunteers of mean age 20.56 ± 2.49 years (n=30, M/F 22/8) underwent recording of supine resting electrocardiogram under standard test conditions for HRV analysis. The volunteers then underwent pre-exercise assessment of resting heart rate (HR), blood pressure (BP) and respiratory rate (RR) in supine position and after five minutes of assuming standing posture followed by an acute maximal graded treadmill exercise test (Ball State University Protocol) until volitional exhaustion providing total test time (TT), cumulative work output (WO) achieved, cumulative metabolic equivalent of task (METs) achieved, derived VO2max achieved and drop in recovery HR data. Spectral analysis of short-term heart rate variability was performed using Kubios HRV software version 2.1 yielding time-domain (mean of RR intervals, root mean square of successive differences - rMSSD, standard deviation of normal to normal intervals - SDNN, the number of pairs of successive NNs that differ by more than 50 ms - NN50, the proportion of NN50 divided by total number of NNs - pNN50) and frequency-domain (VLF, LF, and HF band powers and peak frequencies) measures. Data were analysed using Pearson’s Correlation Coefficient with Bootstrap confidence interval statistics. RESULTS: The spectral analysis of heart rate variability parameters do not correlate significantly with the acute maximal graded treadmill exercise parameters. However, resting supine heart rate and resting supine systolic BP show significant negative correlation with drop in recovery heart rate at 5th minute (r = -0.501 and -0.496 at 95% confidence interval of -0.686 to -0.304 and -0.710 to -0.242 respectively, at p value < 0.05). CONCLUSIONS: Short-term heart rate variability parameters do not have any influence on the acute maximal exercise performance parameters of an individual. Resting heart rate and systolic blood pressure correlate with heart rate recovery which is a predominantly parasympathetic function.

Cardiorespiratory fitness in groups with different physical activity levels.

The aim of the study was to determine how different categorizations of self-reported and objectively measured physical activity (PA) reflect variations in cardiorespiratory fitness (VO2max ). A total of 759 individuals (366 women) with a mean age of 48.5 years (SD 14.4) wore an accelerometer (ActiGraph GT1M) for seven consecutive days and answered the short International Physical Activity Questionnaire (IPAQ). VO2max was directly measured during a continuous graded exercise treadmill test until exhaustion. Men and women categorized as highly active by IPAQ had 9% and 13% higher VO2max , respectively, than those reporting a low PA level (P < 0.05). Men and women meeting the PA recommendation of 150 min/week of daily moderate intensity PA, measured by accelerometer, had 13% and 9% higher VO2max , respectively, than participants not meeting this recommendation (P < 0.01). No significant differences in average sedentary time, analyzed in total min/day and in bouts of 10 and 30 min, were found between participants with high or low cardiorespiratory fitness. However, women spent less time than men in bouts of sedentary behaviors. Self-reported PA by IPAQ and objectively measured PA by accelerometer were both useful instruments for detecting differences in VO2max .

Effects of interval training-based glycolytic capacity on physical fitness in recreational long-distance runners

PurposeThe aim of this study was to investigate the influence of 8-week-long interval training (targeting glycolytic capacity) on selected markers of physical fitness in amateur long-distance runners.MethodsThe study involved 17 amateur long-distance runners randomly divided into an experimental (&lt;i&gt;n&lt;/i&gt; = 8) and control (&lt;i&gt;n&lt;/i&gt; = 9) group. The control group performed three or four continuous training sessions per week whereas the experimental group performed two interval running training sessions and one continuous running training session. A graded treadmill exercise test and the 12-min Cooper test were performed pre- and post-training.ResultsVO&lt;sub&gt;2&lt;/sub&gt;max and the rate of recovery increased in the experimental group. Relative oxygen uptake, minute ventilation, and heart rate speed decreased in low- (6 km/h) and medium-intensity (12 km/h) running.ConclusionsBoth training modalities showed similar results. However, the significant differences in training volume (4–8 min interval training vs. 40–150 min continuous training) indicates that the modalities targeting glycolytic capacity may be more efficient for amateur runners prepare for long-distance events.

Impaired Systolic Blood Pressure Recovery and Heart Rate Recovery After Graded Exercise in Patients With Metabolic Syndrome

The aim of this study was to evaluate and compare systolic blood pressure recovery and heart rate recovery (HRR) values obtained at various time intervals after maximal graded exercise treadmill testing between patients with metabolic syndrome (MS) and the controls without MS. To our knowledge, this is the first study indicating systolic blood pressure recovery (SBPR) impairment and its relations to HRR and other variables in this group of patients.The study population included 110 patients with MS (67 men, 43 women; mean age: 46 ± 9 years) and 110 control subjects who did not meet the criteria for MS (58 men, 52 women; mean age: 44 ± 10 years). All patients were selected from nonobese, apparently healthy sedentary individuals who had the ability to perform maximum exercise testing. SBPR was assessed by calculating the ratio of systolic blood pressure (SBP) obtained in the third minute of the recovery period to either the peak-exercise SBP or the SBP in the first minute of the recovery period after graded exercise testing. HRR values were calculated by subtracting the HR at the first, second, third, fourth, and fifth minutes of the recovery period from the HR reached at peak exercise.There was no significant difference found between the 2 groups with respect to age and sex distribution. As expected, patients with MS had higher waist circumference, fasting plasma glucose and serum triglyceride, and lower high-density lipoprotein cholesterol compared with control subjects. All HRR values calculated in the first, second, third, fourth, and fifth minutes were significantly detected lower in the MS group compared with the control group (HRR 1st: 32 ± 10 vs 36 ± 11; P = 0.009; HRR 2nd: 47 ± 10 vs 51 ± 11; P = 0.02; HRR 3rd: 53 ± 11 vs 58 ± 12; P = 0.001; HRR 4th: 57 ± 11 vs 64 ± 12; P < 0.001; HRR 5th: 60 ± 16 vs 69 ± 15; P < 0.001). In addition, calculated mean values for SBPR1 and SBPR2 were >1 in patients with MS (1.01 ± 0.2 vs 0.91 ± 0.1 and 1.01 ± 0.1 vs 0.94 ± 0.1) and these were statistically significant compared with the control group (P < 0.001 and P = 0.002, respectively). The existence of MS was found to be the only parameter that was independently and positively related to SBPR values in the study population.Our findings suggest that only the existence of MS itself, not the presence of any MS components, is independently associated with SBPRs. We are of the opinion that significantly impaired SBPR values, in addition to the decreased HRR values observed in this group of patients, such as those with MS, may especially help identify patients with potentially increased cardiovascular risk despite normal exercise stress testing findings.

Vitamin D status and V[combining dot above]O2peak during a skate treadmill graded exercise test in competitive ice hockey players.

Vitamin D status has been associated with cardiorespiratory fitness (CRF) in cross-sectional investigations in the general population. Data characterizing the association between 25-hydroxyvitamin D (25(OH)D) concentration and CRF in athletes are lacking. Junior and collegiate ice hockey players were recruited from the Minneapolis, MN (44.9° N), area during the off-season period (May 16-June 28). The purpose of this study was to examine the cross-sectional association between 25(OH)D concentration and CRF in a sample population of competitive ice hockey players. Circulating 25(OH)D level was assessed from a capillary blood sample analyzed using liquid chromatography-tandem mass spectrometry. V[Combining Dot Above]O2peak during a skate treadmill graded exercise test (GXT) was used to assess CRF. Data on both 25(OH)D concentration and V[Combining Dot Above]O2peak were available for 52 athletes. Insufficient 25(OH)D concentrations were found in 37.7% of the athletes (<32 ng·ml). Vitamin D status was not significantly associated with any physiological or physical parameter during the skate treadmill GXT.

Efectos del entrenamiento pliométrico sobre la resistencia cardiorrespiratoria de niños y adolescentes con síndrome de Down

AimTo ascertain the effects of 21 weeks of circuit training, including plyometric jumps, on cardiorespiratory fitness of youths with Down syndrome (DS). MethodsTwenty-seven children and adolescents aged 10 to 19 years with DS participated in this study and were divided in two groups: exercise (EXE, n=14) and control (CON, n=13). Work time, peak values of oxygen consumption, respiratory exchange ratio, heart rate and minute ventilation of the participants were measured in pre- and post-training moments with a graded exercise treadmill test. ResultsEXE group increased all their cardiorespiratory parameters compared to baseline after 21 weeks of training (all p<.05). Additionally, and despite having similar pre-training values, EXE group showed higher values than CON group in all cardiorespiratory parameters after training (all p<.05). ConclusionIt may be concluded that youths with DS can achieve improvements in several cardiorespiratory parameters when performing 21 weeks of training including plyometric exercises.

Effects of a circuit training including plyometric jumps on cardiorespiratory fitness of children and adolescents with Down syndrome

AimTo ascertain the effects of 21 weeks of circuit training, including plyometric jumps, on cardiorespiratory fitness of youths with Down's syndrome (DS). MethodsTwenty-seven children and adolescent aged 10 to 19 years with DS participated in this study and were divided in two groups: exercise (EXE, n=14) and control (CON, n=13). Work time, peak values of oxygen consumption, respiratory exchange ratio, heart rate and minute ventilation of the participants were measured pre- and post-training with a graded exercise treadmill test. ResultsEXE group increased all their cardiorespiratory parameters compared to baseline after 21 weeks of training (all P<.05). Additionally, and despite having similar pre-training values, the EXE group showed higher values than the CON group in all cardiorespiratory parameters after training (all P<.05). ConclusionIt may be concluded that youths with Down syndrome can achieve improvements in several cardiorespiratory parameters when performing 21 weeks of training including plyometric exercises.

The relationship between exercise intensity and preferred music intensity.

Self-selected music intensity (i.e., volume) and perceived music usefulness were examined across a range of exercise intensities that were standardized around ventilatory threshold (VT). The influence of gender and athletic status (i.e., athletes vs. recreational exercisers) was also explored. Participants were male (n 23) and female (n 19) volunteers; 18 were recreational exercisers, and 24 were collegiate athletes. Participants completed a maximal treadmill graded exercise test (GXT) while listening to motivational music. Participants controlled the music volume, and could adjust it at any time during the GXT. Ratings of music usefulness were collected at 1-min intervals throughout the test. It was expected that both music intensity and perceived music usefulness would be highest at or immediately after VT, and lowest at the extreme beginning and end of the test. This quadratic trend was confirmed by our results. Recreational exercisers preferred louder music than athletes, and made more volume adjustments at points beyond VT. No gender differences were observed for music intensity. Music was perceived as increasingly useful up until the point of VT, after which ratings plateaued and then declined during cool-down; however, a gender task intensity interaction revealed that whereas males followed a clear quadratic trend, females rated music as increasingly useful until the end point of the GXT. The results of this study are supportive of the information processing framework. Individual differences in preferred music intensity and use of music should be considered in future investigations.

Validation of the step test and exercise prescription tool for adults.

Canadian clinical practice guidelines for the management of diabetes highlight the value of physical activity for improving clinical markers and risk factors for diabetes. The use of tools like the Step Test and Exercise Prescription (STEP) in clinical practice facilitates chronic disease management and prevention through the promotion of healthy physical activity. The validity and reliability of STEP has been established previously for use with adults 65 to 85 years of age. The purpose of this study was to test the validity of the prediction equation for VO₂max from the STEP tool for use with adults older than 65 years. Forty participants completed both the predictive self-paced VO₂max stepping protocol from the STEP tool, and a maximal graded exercise treadmill test with breath-by-breath analysis of expired gases. Tests were completed in random order, and participants rested between tests until blood pressure returned to baseline. The average age of the sample was 43±14 years. There was a strong relationship between predicted VO₂max from STEP and direct measures of VO₂max from the maximal treadmill test in the present study (r=.78, p<0.001). Bland-Altman analysis demonstrated statistical agreement between tests, although there was systematic overestimation of 6.4 mL/kg/min. STEP is an evidence-based cardiorespiratory fitness assessment and exercise prescription tool appropriate for use by various health professionals in clinical practice. The prediction equation for VO₂max from the STEP tool is valid for use with adults 18 to 85 years of age. However, more research is warranted to explore age corrections to the prediction algorithm among younger adults.

Effects of Exercise Type on Hemodynamic Responses and Cardiac Events in ACS Patients.

[Purpose] This study investigated the effects of mid, and high exercise intensities on hemodynamic responses and cardiac events during two exercise types of treadmill exercise (TM) and cycle ergometer exercises (CE) in patients with acute coronary syndrome (ACS). [Subjects] Patients who had percutaneous coronary intervention (PCI) for ACS and were participating in cardiac rehabilitation program were included. [Methods] The patients were assessed for hemodynamic responses, cardiac events, and rate of perceived exertion (RPE) with target heart rates of 60% and 85% heart rate reserve (HRR) during TM and CE. [Results] Maximum systolic blood pressure (SBP), diastolic blood pressure (DBP), RPE, and rate pressure product (RPP) measured during CE were significantly higher than their values in TM at the same exercise intensities. The highest SBP was shown at 85% HRR during CE. SBPmax to SBPmax ratios obtained during the graded exercise test (GXT) showed that all %SBPmax were significantly greater in CE than in TM at the same exercise intensities. Out of 102 patients, cardiac events occurred in 8 at 85% HRR during CE, and 1 at 85% HRR during TM. Patients with cardiac events (CE-E) had significantly higher %SBP, %RPP, and RPE at 85% HRR than those without events (CE-NE) during CE. [Conclusion] Prescribing exercise based on the intensity obtained in a treadmill GXT may expose patients to cardiovascular complications such as higher RPP, higher exercise intensity, and cardiac events during CE.

Associations between food groups, dietary patterns, and cardiorespiratory fitness in the Coronary Artery Risk Development in Young Adults study

Few studies have investigated the association between overall diet and cardiorespiratory fitness (CRF). We aimed to investigate associations of food groups, a diet-quality score, and dietary patterns with CRF in black and white adults. We included 2632 participants aged 38-50 y who attended the year 20 exam of the Coronary Artery Risk Development in Young Adults (CARDIA) study and Coronary Artery Risk Development in Young Adults Fitness Study (CFS) conducted in 2005-2006. Diet was assessed by using a validated diet history. A dietary score and 2 types of patterns were included as follows: the a priori diet-quality score and meat and fruit-vegetable dietary patterns derived from principal components analysis. CRF was assessed by using a graded exercise treadmill test. Linear regression models regressed the treadmill duration on food groups and dietary scores and patterns overall and in race-sex subgroups. Grains (whole and refined), processed meats, and beverages (coffee, meal-replacement drinks, beer, and wine) were positively associated with the treadmill duration overall; whole fruit (not juices), organ meats, fried meats and fish, and soy and nondairy products were negatively associated. The a priori diet-quality score was positively associated with the duration overall and in all race-sex subgroups (P <0.05) except black men. The meat pattern was negatively associated with the duration in white men and white women only. The fruit-vegetable pattern was positively associated with duration in white women only. Overall, the a priori diet-quality score was positively associated with CRF in this cohort of black and white adults, whereas the meat dietary pattern was negatively associated only in whites. The CARDIA study and CFS were registered at clinicaltrials.gov as NCT00005130 and NCT00106457, respectively.

Estimated V[Combining Dot Above]O2max From the Rockport Walk Test on a Nonmotorized Curved Treadmill

The Rockport Walk Test (RWT) is a 1-mile walk used to estimate the maximal volume of oxygen uptake (V(O2)max). The purpose of this study was to validate the RWT on a nonmotorized curved treadmill (CT). Twenty-three healthy adults (10 females; 19-44 years old) participated. One trial of the RWT was performed on a measured indoor track (RWTO) and another on the CT (RWTC) on different days in randomized order. Heart rate (HR) and completion time were used to calculate V(O2)max using 6 different general and gender specific equations from previous research. Subjects also performed a treadmill graded exercise test (GXT), which was used as the criterion measure for V(O2)max. Completion times and HR between the 2 RWT were compared using dependent t-tests. Estimated V(O2)max values were compared between the RWTC, RWTO, and GXT through repeated measures analysis of variance, Pearson's correlations (r), and Bland-Altman's plots. There was no difference between completion times for the RWTO and RWTC but HRs were significantly higher with RWTC. When the same equation was applied to the RWTO and RWTC, there were no similar results. All V(O2)max estimations were different from observed V(O2)max except for the estimation from the relative general Kline et al. equation on the RWTO. Despite high correlations (r = 0.75-0.91), the RWTC underestimated V(O2)max. The RWTC underestimates V(O2)max but may be beneficial if a new equation were created specifically for the CT. With appropriate equations for the CT, the RWTC would provide an alternate form of V(O2)max testing.

Exercise Intolerance in Individuals With Postconcussion Syndrome

Little is known about exercise intolerance or the utility of an exercise evaluation in patients with postconcussion syndrome (PCS). To assess exercise intolerance in male and female patients with PCS. Cross-sectional study. Laboratory setting. Participants included a convenience sample of 34 patients with PCS (17 males, 17 females; age = 25.9 ± 10.9 years) and 22 uninjured individuals on whom we gathered historical deidentified laboratory data (control group; 11 males, 11 females; age = 23.3 ± 6.2 years). Self-reported symptoms, heart rate, systolic and diastolic blood pressures (BPs), and the Borg rating of perceived exertion were measured before, during each minute of, and immediately after a graded treadmill exercise test (Balke protocol). Exercise was stopped when participants could no longer maintain the effort or reported the onset of or increase in PCS symptoms. Exercise test duration (8.5 ± 4.4 minutes versus 17.9 ± 3.6 minutes; t51 = 1.8, P < .001), heart rate (142.8 ± 24.1 versus 175.2 ± 17.4; t54 = -5.5, P < .001), and systolic BP (142.1 ± 18.3 mm Hg versus 155.5 ± 24.5 mm Hg; t53 = 2.3, P = .02) were lower, and diastolic BP (78.4 ± 10.2 mm Hg versus 73.5 ± 11.7 mm Hg; t53 = 2.2, P = .03) was higher at test cessation in the PCS than control group. Cox regression showed the odds of a shorter exercise duration were nearly 8 times greater in the PCS than control group (hazard ratio = 7.93; 95% confidence interval = 3.39, 18.56). In the general linear models that adjusted for differences in test duration, rating of perceived exertion was the only physiologic measure to show an overall difference between groups, with the control group reporting higher ratings than the PCS group (t53 = -6.0, P < .001). Within the PCS group, systolic BP was the only measure to show a sex effect, with males showing higher pressure readings than females throughout the exercise tests (t31 = 2.8, P = .009). Patients with PCS had a symptom-limited response to exercise, and the treadmill test was a potentially useful tool to monitor the recovery from PCS.

The Ability of the PACER to Elicit Peak Exercise Response in the Youth

A graded exercise test (GXT) is the standard laboratory method of determining peak aerobic fitness (V˙O2peak). The FITNESSGRAM's Progressive Aerobic Cardiovascular Endurance Run (PACER) test is commonly used to estimate the peak oxygen consumption in the youth in the field.The objective of this study is to compare the peak physiological variables and RPEpeak during a treadmill GXT and the PACER test in 10- to 15-yr-old youths. Participants (20 boys and 25 girls, 12.7 ± 1.7 yr) completed the PACER and treadmill GXT in a randomized order, separated by at least 24 h. HRpeak was measured via telemetry, V˙O2peak and RERpeak were measured using a portable metabolic system, and participants reported RPEpeak at the end of each test. No significant differences were found between the GXT and PACER HRpeak (197 vs 197 beats·min), RERpeak (1.13 vs 1.12), V˙O2peak (45.0 vs 45.9 mL·kg·min), and RPEpeak (8.4 vs 8.3). The SE of the measurement between the GXT V˙O2peak and PACER V˙O2peak was 1.4 mL·kg·min. It appears that the PACER elicits similar peak exercise responses compared with a treadmill GXT. The PACER can also be administered for fitness and functional capacity assessments in healthy and clinical populations.

Crossvalidation of Two 20-M Shuttle-Run Tests for Predicting V[Combining Dot Above]O2max in Female Collegiate Soccer Players

The aim of this study was twofold: (a) to compare the maximal attained speed (MAS) from the 20-m shuttle (MST) and 20-m square-shuttle (SST) tests and (b) to crossvalidate 2 equations for predicting maximal oxygen consumption (VO2max) that were previously developed from MST and SST in a group of female collegiate soccer players. Thirty-nine subjects (age: 20.1 ± 1.5 years) participated in the study. A maximal graded exercise treadmill test was used to measure VO2max. In addition, VO2max was predicted from the MAS obtained during MST ((pred)VO2maxMST) and SST ((pred)VO2maxSST) using previously developed equations. Measured VO2max for the group was 44.2 ± 3.3 ml·kg(-1)·min(-1). The MAS was 12.5 ± 0.6 km·h(-1) for MST and 13.3 ± 0.8 km·h(-1) for SST (p < 0.05). The prediction methods yielded a (pred)VO2maxMST of 49.6 ± 3.9 ml·kg(-1)·min(-1) and predVO2maxSST of 41.8 ± 3.1 ml·kg(-1)·min(-1), which were significantly different from measured VO2max (p < 0.05). The validity statistics revealed the following constant error (CE), correlation coefficient (r), standard error of estimate (SEE), and total error (TE) for (pred)VO2maxMST and (pred)VO2maxSST: CE = 5.35 ± 3.83, r = 0.45 (p < 0.05), SEE = 2.97 ml·kg(-1)·min(-1), TE = 6.39 ml·kg(-1)·min(-1); and CE = -2.43 ± 2.49, r = 0.69 (p < 0.05), SEE = 2.39 ml·kg(-1)·min(-1), TE = 3.43 ml·kg(-1)·min(-1), respectively. Residual plots indicated no proportional bias for either prediction model. The results of this study suggest that female collegiate soccer players had a higher MAS from SST compared with that from MST. In addition, SST appeared to be a more accurate predictor of VO2max than MST in the group of athletes.