Maximal Graded Exercise Test Research Articles

Changes in the Second Ventilatory Threshold Following Individualised versus Standardised Exercise Prescription among Physically Inactive Adults: A Randomised Trial.

The second ventilatory threshold (VT2) is established as an important indicator of exercise intensity tolerance. A higher VT2 allows for greater duration of higher intensity exercise participation and subsequently greater reductions in cardiovascular disease (CVD) risk. This study aimed to compare the efficacy of standardised and individualised exercise prescription on VT2 among physically inactive adults. Forty-nine physically inactive male and female participants (48.6 ± 11.5 years) were recruited and randomised into a 12-week standardised (n = 25) or individualised (n = 24) exercise prescription intervention. The exercise intensity for the standardised and individualised groups was prescribed as a percentage of heart rate reserve (HRR) or relative to the first ventilatory threshold (VT1) and VT2, respectively. Participants were required to complete a maximal graded exercise test at pre-and post-intervention to determine VT1 and VT2. Participants were categorised as responders to the intervention if an absolute VT2 change of at least 1.9% was attained. Thirty-eight participants were included in the analysis. A significant difference in VT2 change was found between individualised (pre vs. post: 70.6% vs. 78.7% maximum oxygen uptake (VO2max)) and standardised (pre vs. post: 72.5% vs. 72.3% VO2max) exercise groups. Individualised exercise prescription was significantly more efficacious (p = 0.04) in eliciting a positive response in VT2 (15/19, 79%) when compared to the standardised exercise group (9/19, 47%). Individualised exercise prescription appears to be more efficacious than standardised exercise prescription in eliciting a positive VT2 change among physically inactive adults. Increasing VT2 allows for greater tolerance to higher exercise intensities and therefore greater cardiovascular health outcomes.

Determination of Second Lactate Threshold Using Near-infrared Spectroscopy in Elite Cyclists.

The use of near-infrared spectroscopy could be an interesting alternative to other invasive or expensive methods to estimate the second lactate threshold. Our objective was to compare the intensities of the muscle oxygen saturation breakpoint obtained with the Humon Hex and the second lactate threshold in elite cyclists. Ninety cyclists performed a maximal graded exercise test. Blood capillary lactate was obtained at the end of steps and muscle oxygenation was continuously monitored. There were no differences (p>0.05) between muscle oxygen oxygenation breakpoint and second lactate threshold neither in power nor in heart rate, nor when these values were relativized as a percentage of maximal aerobic power or maximum heart rate. There were also no differences when men and women were studied separately. Both methods showed a highly correlation in power (r=0.914), percentage of maximal aerobic power (r=0.752), heart rate (r=0.955), and percentage of maximum heart rate (r=0.903). Bland-Altman resulted in a mean difference of 0.05±0.27 W·kg-1, 0.91±4.93%, 0.63±3.25 bpm, and 0.32±1.69% for power, percentage of maximal aerobic power, heart rate and percentage of maximum heart rate respectively. These findings suggest that Humon may be a non-invasive and low-cost alternative to estimate the second lactate threshold intensity in elite cyclists.

Factors Associated with Age-Related Declines in Cardiorespiratory Fitness from Early Adulthood Through Midlife: CARDIA.

This study aimed to describe maximal and submaximal cardiorespiratory fitness from early adulthood to midlife and examine differences in maximal fitness at age 20 yr and changes in fitness overtime by subcategories of sociodemographic, behavioral, and health-related factors. Data include 5018 Coronary Artery Risk Development in Young Adults participants (mean (SD) age, 24.8 (3.7) yr; 53.3% female; and 51.4% Black participants) who completed at least one maximal graded exercise test at baseline and/or the year 7 and 20 exams. Maximal and submaximal fitness were estimated by exercise duration and heart rate at the end of stage 2. Multivariable adjusted linear-mixed models were used to estimate fitness trajectories using age as the mechanism for time after adjustment for covariates. Fitness trajectories from ages 20 to 50 yr in 5-yr increments were estimated overall and by subgroups determined by each factor after adjustment for duration within the less favorable category. Mean (95% confidence interval) maximal fitness at age 20 and 50 yr was 613 (607-616) and 357 (350-362) s; submaximal heart rate during this period also reflected age-related fitness declines (126 (125-127) and 138 (137-138) bpm). Compared with men, women had lower maximal fitness at age 20 yr (P < 0.001), which persisted over follow-up (P < 0.001); differences were also found by race within sex strata (all P < 0.001). Differences in maximal fitness at age 20 yr were noted by socioeconomic, behavioral, and health-related status in young adulthood (all P < 0.05), which persisted over follow-up (all P < 0.001) and were generally consistent in sex-stratified analyses. Targeting individuals experiencing accelerated fitness declines with tailored intervention strategies may provide an opportunity to preserve fitness throughout midlife to reduce lifetime cardiovascular disease risk.

Comparison of the lymphocyte response to interval exercise versus continuous exercise in recreationally trained men

The purpose of this investigation was to compare changes in circulating lymphocyte subset cell counts between high-intensity interval exercise (HIIE), sprint interval exercise (SIE), and moderate-intensity continuous exercise (MICE). Recreationally active men (n ​= ​11; age: 23 ​± ​4 ​yr; height: 179.9 ​± ​4.5 ​cm; body mass: 79.8 ​± ​8.7 ​kg; body fat %:12.6 ​± ​3.8%; V̇O2max: 46.6 ​± ​3.9 ​ml⋅kg−1⋅min−1) completed a maximal graded exercise test to determine maximal oxygen uptake (V̇O2max) and three duration-matched cycling trials (HIIE, SIE, and MICE) in a randomized, counterbalanced fashion. HIIE consisted of fifteen 90-s bouts at 85% V̇O2max interspersed with 90-s active recovery periods. SIE consisted of fifteen 20-s bouts at 130% maximal power and 160-s active recovery periods. MICE was a continuous bout at 65% V̇O2max. Total exercise duration was 53 ​min in all three trials, including warm-up and cool-down. Blood was collected before, immediately post, 30 ​min, 2 ​h, 6 ​h, and 24 ​h post-exercise. Changes in lymphocyte subset counts, and surface expression of various markers were analyzed via flow cytometry. Changes were assessed using mixed model regression analysis with an autoregressive first order repeated measures correction. Significant decreases were observed in absolute counts of CD56dim NK cells, CD19+ B cells, CD4+ T cells, and CD8+ T cells 30 ​min and 24-h post-exercise in all three trials. Despite resulting in greater total work and oxygen consumption, MICE elicited similar changes in lymphocyte subset counts and receptor expression compared to both SIE and HIIE. Similarly, while the two interval trials resulted in differing oxygen consumption and total work, no differences in the lymphocyte response were observed. Though both forms of exercise resulted in declines in circulating lymphocyte cell counts, neither exercise type provides an immune-related advantage when matched for duration.

Physical fitness, but not physical activity, is associated with mental health in apparently healthy young adults.

The prevalence of mental health disorders is rising globally. Despite the popularity of exercise as a strategy to improve mental health in individuals with anxiety or depression, there is a paucity of literature on this topic in apparently healthy young individuals who are free from mental illness. We characterized relationships between actigraphy-derived physical activity levels and cardiorespiratory fitness (V̇O<inf>2max</inf>; via maximal graded exercise testing), with mental health assessed using psychometric questionnaires (POMS and PSS) in apparently healthy young adults (26±4.3yrs; 22 women and 26 men). In women and men combined, relative V̇O<inf>2max</inf> (33.5±8.1 mL/kg/min) was associated (P<0.01) with POMS (r=-0.454) and PSS (r=-0.510) scores, and relationships between fitness and POMS were preserved (P<0.05) after controlling for body fat (27.2±9.9%). Additionally, V̇O<inf>2max</inf> was associated (P<0.05) with numerous POMS subcomponents (tension, anger, fatigue, depression, confusion; all P<0.05). No relationships (P>0.05) were observed between physical activity profiles (sedentary time, light intensity time, moderate-vigorous intensity time, total steps, counts per day) with POMS or PSS scores, and only total steps was associated with relative V̇O<inf>2max</inf> (r=0.331; P=0.021). Relationships between relative V̇O<inf>2max</inf> and POMS scores were also observed in men (r=-0.407, P=0.039) and women (r=-0.490; P=0.021) individually, but V̇O<inf>2max</inf> and PSS relationships were exclusive to men (r=-0.516, P=0.007). Independent of body composition, cardiorespiratory fitness, but not actigraphy-derived physical activity, is associated with mental health in apparently healthy young men and women. To maximize mental health benefits, exercise training interventions are advised to focus on eliciting improvements in cardiorespiratory fitness.

Assessment of the Relationship Between Executive Function and Cardiorespiratory Fitness in Healthy Older Adults.

Associations between cardiorespiratory fitness and brain health in healthy older adults have been reported using a variety of cardiorespiratory fitness estimates (CRFe). Using commonly used methods to determine CRF, we assessed the relationship between CRFe and executive function performance. Healthy older adults (n = 60, mean age 68 years, 77% women), underwent three CRF tests: a Maximal Graded Exercise Test performed on a cycle ergometer, the Rockport Fitness Walking Test, and a Non-Exercise Prediction Equation. Executive function was assessed by a computerized cognitive assessment using an N-Back task (updating cost) and a Stroop task (interference cost, global and local switch cost). Multiple hierarchical regression analyses were conducted to assess the relationship between different CRFe and executive function performance. Regardless of age and education, cardiorespiratory fitness estimated from the Maximal Graded Exercise Test and the Rockport Fitness Walking Test was significantly associated with the global switch cost. All CRFe were associated with the interference cost. No association was observed between CRFe and local switching costs or the updating costs. In the present study, not all subcomponents of executive function were related to CRFe. Interestingly, the executive functions that were associated with CRFe are those that are known to be the most affected by aging.

Low-Volume 고강도 인터벌 트레이닝이 비만 성인의 혈중 아디포넥틴, 대사증후군 위험요인 및 심폐 체력에 미치는 영향

Purpose: The purpose of this study is to investigate the effects of low-volume high-intensity interval training on adiponectin, metabolic syndrome risk factors and aerobic capacity in obese adults.<BR> Method: Twenty-one obese men participated in the group of low-volume high-intensity interval training (LV-HIIT; n=7), moderate-intensity continuous training (MICT; n=7) and control (CON; n=7), respectively. All subjects measured body composition, blood test (adiponectin, HDL-C, glucose, and triglyceride) and maximal graded exercise test before the intervention and after six weeks. A two-way repeated measures ANOVA demonstrated a significant difference (p<.05). Bonferroni’s method was used for post-hoc analysis when there is a significant.<BR> Results: The results of this study are as follows. 1) Body composition was significantly improved in the low-volume high-intensity interval training group and the moderate-intensity continuous training group. 2) Adiponectin concentration was significantly increased in the low-volume high-intensity interval training group and moderate-intensity continuous training group. 3) The waist circumference, triglyceride, and glucose of metabolic syndrome risk factors significantly decreased in the low-volume high-intensity interval training group and moderate-intensity continuous training group. There was no significant difference in blood pressure and HDLC 4) Aerobic capacity was significantly improved in the low-volume high-intensity interval training group and moderate- intensity continuous training group.<BR> Conclusion: In summary, the findings in this study are that despite conducting low volume, Low-Volume high intensity interval training is efficient training compared to moderate intensity continuous training for improving adiponectin, metabolic syndrome risk factors and aerobic capacity.

Efficacy of estimating VO2max with the Heart Rate Ratio Method in middle-aged and older adults.

Investigate difference, agreement, and bias between maximal oxygen consumption (VO2max) measured by indirect calorimetry and the Heart Rate Ratio Method (HRRM) for estimating VO2max using measured and age-predicted maximum heart rate (HRmax) in a sample of middle-aged and older adults. Eleven men and nine women (age: 61.8 ± 8.5years, VO2max: 36.6 ± 9.5mL/kg/min, N = 20) had their VO2max measured via a maximal graded exercise test and confirmed using a verification bout on a treadmill ergometer. Participants' VO2max was estimated via the HRRM using measured and age-predicted HRmax. Difference, agreement, and bias between methods were assessed using a one-way repeated measures Analysis of Variance (ANOVA), Lin's concordance correlation coefficient, and Bland-Altman plots, respectively. There were no statistical differences between methods of assessing VO2max, F(1.13, 21.47) = 0.583, p = 0.473, generalized eta-squared = 0.012. The standard error of the estimate (SEE) for the HRRM using measured or predicted HRmax was 5.2% and 5.6% of the mean VO2max, respectively. Both HRRM predictions had poor agreement with VO2max (rc ≤ 0.40). There was a systematic bias to underestimate as VO2max increased for HRRM using measured HRmax, F(1, 18) = 17.40, p < 0.001, and when using an age-predicted HRmax, F(1, 18) = 13.39, p = 0.002. Both versions of the HRRM have poor agreement, relatively large SEEs, and a bias to misrepresent VO2max. When possible, VO2max should be measured via a maximal graded exercise test with indirect calorimetry for middle-aged and older adults.

The New Way to Exercise? Evaluating an Innovative Heart-rate-controlled Exergame.

Exergames may offer novel opportunities to expand physical activity. Most games, however, only result in low to moderate-intensity activities that are too low to allow relevant physical adjustments. In the present study, the exercise intensity of a new, heart rate controlled, functional fitness game was assessed. 28 subjects (aged 24.8±3.8 yrs; 46% female; BMI 23.2±2.3 kg/m2) were enrolled in this study. VO2max and maximal heart rate (HRmax) were assessed during a maximal graded exercise test on a treadmill and compared with the oxygen consumption (VO2) and heart rate (HR) during a game in the ExerCube.In the ExerCube, the subjects reached a peak HR of 187.43±9.22 bpm, which corresponds to 96.57±3.64% of their HRmax. The mean HR throughout the game was 167.11±10.94 bpm, corresponding to 86.07±4.33% of HRmax. VO2peak reached 41.57±5.09 ml/kg/min during the game in the ExerCube, which corresponds to 84.75±7.52% of VO2max. The mean VO2 consumption during the game reached 32.39±4.04 ml/kg/min, which corresponds to 66.01±5.09% of VO2max. The ExerCube provides a form of vigorous physical exercise. Due to its playful, immersive, and motivating nature, the ExerCube seems to be a promising tool to facilitate physical activity.

A New Fitness Test of Estimating VO2max in Well-Trained Rowing Athletes.

BackgroundThis study was designed to investigate the validity of maximal oxygen consumption (VO2max) estimation through the Firstbeat fitness test (FFT) method when using submaximal rowing and running programs for well-trained athletes.MethodsWell-trained flatwater rowers (n = 45, 19.8 ± 3.0 years, 184 ± 8.7 cm, 76 ± 12.9 kg, and 58.7 ± 6.0 mL⋅kg–1⋅min–1) and paddlers (n = 45, 19.0 ± 2.5 years, 180 ± 7.7 cm, 74 ± 9.4 kg, and 59.9 ± 4.8 mL⋅kg–1⋅min–1) completed the FFT and maximal graded exercise test (GXT) programs of rowing and running, respectively. The estimated VO2max was calculated using the FFT system, and the measured VO2max was obtained from the GXT programs. Differences between the estimated and measured VO2max values were analyzed to assess the accuracy and agreement of the predictions. Equations from the previous study were also used to predict the VO2max in the submaximal programs to compare the accuracy of prediction with the FFT method.ResultsThe FFT method was in good agreement with the measured VO2max in both groups based on the intraclass correlation coefficients (>0.8). Additionally, the FFT method had considerable accuracy in VO2max estimation as the mean absolute percentage error (≤5.0%) and mean absolute error (<3.0 mL⋅kg–1⋅min–1) were fairly low. Furthermore, the FFT method seemed more accurate in the estimation of VO2max than previously reported equations, especially in the rowing test program.ConclusionThis study revealed that the FFT method provides a considerably accurate estimation of VO2max in well-trained athletes.

Constant low-to-moderate mechanical asymmetries during a treadmill graded exercise test

ABSTRACT This study describes asymmetry in key mechanical variables during a treadmill-based, running graded exercise test (GXT). Twenty-one recreationally trained male runners completed a continuous, maximal GXT on an instrumented treadmill, starting at 9 km.h−1 with speed increases of +0.5 km.h−1 every 30 s, for the determination of ventilatory threshold (VT), respiratory compensation point (RCP), and maximal oxygen uptake (MAX). Ground reaction forces were recorded continuously and subsequently averaged from 10 consecutive steps corresponding to VT, RCP and MAX intensity stages (13.4 ± 1.2 km.h−1, 16.0 ± 1.6 km.h−1 and 18.2 ± 1.5 km.h−1, respectively). Asymmetry scores were assessed from the “symmetry angle” (SA) formulae, where a score of 0%/100% indicates perfect symmetry/asymmetry; these were then compared between the three intensity stages. There was no influence of exercise intensity on SA scores for any of the sixteen biomechanical variables (P > 0.222). The group mean SA scores did not exceed 1.5% for spatio-temporal variables (contact time, aerial time, frequency and step length). There were larger mean SA scores for mean loading rate (3.7 ± 2.7%) and most spring-mass model variables (vertical stiffness: 2.2 ± 1.6% and leg stiffness: 1.7 ± 1.4%). The SA scores were ∼1.0–3.5% for braking and propulsive phase durations, peak forces, and resulting impulses. Lower extremities behave similarly at submaximal and maximal intensities during GXT, indicating that runners maintained relatively even strides as intensity increased. However, practitioners must be careful not to infer the presence of asymmetry during GXT based on a single variable, given the lower SA scores for spatio-temporal parameters. Highlights Our comprehensive list of sixteen mechanical variables provides a mechanical norm of expected asymmetry during treadmill graded exercise testing for recreationally trained runners. The stride pattern across submaximal and maximal exercise intensities remains consistent between limbs, with mechanical asymmetries being more individual-specific than intensity stage-dependent. Low to moderate asymmetry is a natural phenomenon in recreationally trained runners during treadmill graded exercise testing; notwithstanding, asymmetry scores appear inconsistent between mechanical parameters.

Respiratory Response to Underwater and Land‐based Cycling at the Matched Oxygen Uptake

Water immersion increases breathing effort against elevated hydrostatic pressure. Thus, aquatic exercise training may have a greater benefit for the respiratory function when compared to the same intensity of exercise performed on dryland. The purpose of this study was to investigate the effect of underwater cycling on the respiratory function and breathing pattern when compared to land-based cycling performed at the matched exercise intensity. Ten healthy men performed maximal graded exercise test and 15 minutes of incremental water-based cycling exercise (WE) and land-based cycling exercise (LE) on separate days. In WE, cycling began at 30 rpm, and the cadence was increased by 15 rpm every 5 minutes. 3 paddles were attached to the wheel of stationary bicycle to increase pedaling resistance. In LE, participants cycled continuously at 60 rpm for 15 minutes while wattage was adjusted to match oxygen uptake (VO2) to the WE condition. Using spirometry, respiratory function and respiratory muscle pressure were measured before and after cycling, and the magnitude of change between pre- and post- exercise was also measured. Breathing pattern was measured continuously during cycling. Water temperature and immersion level were kept at 31.5 ℃ and xiphoid appendix, respectively. VO2 duringcycling in water and on dryland was similar. Minute ventilation, inspiratory and expiratory volumes, and respiratory rate increased whereas, inspiratory and expiratory times decreased as the cycling intensity (VO2) increased (all P < 0.05). Respiratory rate was slightly higher at 60 rpm in WE than LE (27 ± 3 vs. 24 ± 3 bpm, P = 0.053). Inspiratory time was significantly higher at rest in WE than LE (1.4 ± 0.1 vs. 1.2 ± 0.0 sec, P < 0.05). After cycling exercise, change in the forced expiratory volume in one second and change in the peak expiratory flow were significantly lower in WE than LE (-0.04 ± 0.15 vs. 0.06 ± 0.10 L, P < 0.05. -0.37 ± 0.87 vs. 0.04 ± 0.63 L, P < 0.05, respectively). These data suggest that the respiratory and breathing responses were mostly similar during underwater and land-based cycling when VO2 is matched in both conditions. However, breathing may slightly be shallower during a higher-intensity aquatic cycling which may have chronic effects on respiratory function after multiple bouts of aquatic cycling for a longer term.

INFLUENCE OF ANTIHYPERTENSIVE MEDICATION STATUS ON THE BLOOD PRESSURE RESPONSES TO DYNAMIC EXERCISE IN HYPERTENSIVE INDIVIDUALS

Objective: To investigate if the blood pressure (BP) response to a maximal graded exercise test (GXT) is influenced by antihypertensive medication (AHM) in monotherapy or in combination. Design and method: Thirty-one hypertensive individuals with obesity under AHM treatment targeting the renin-angiotensin-aldosterone system (RAAS) were divided into 3 groups depending on the number of AHM taken: monotherapy (MONO, n = 15), two drugs (DUAL, n = 8) or 3 drugs (TRIPLE, n = 8). By using a randomized, double-blind, placebo-controlled, crossover design, participants completed two trials (i.e. AHM vs PLAC). In each trial, 24-h ambulatory blood pressure (ABP), plasma renin activity (PRA), aldosterone concentration and the BP responses to a GXT were measured and compared among groups. Results: In AHM trials, 24-h ABP was significantly lower (127 ± 12 vs 134 ± 10 mmHg, P &lt; 0.001) and PRA higher (4.0 ± 2.7 vs 1.9 ± 1.8 ng/mL/h, P &lt; 0.001) in comparison to PLAC, without differences between groups in any variable (P &gt; 0.05). There was not any group nor trial effect on plasma aldosterone concentration (P &gt; 0.05). During incremental exercise, there were no differences between trials nor among groups in the BP response to incremental exercise, reaching similar peak systolic BP (211 ± 25 vs 206 ± 25 mmHg in AHM and PLAC, respectively, P = 0.118). Regarding the heart rate (HR) response to exercise, the TRIPLE group showed a higher HR at submaximal intensities in AHM vs PLAC (+7 ± 4 bpm, P &lt; 0.005). Conclusions: Antihypertensive medication reduces ABP but does not have any effect on systolic BP during exercise, independently of the number of drugs taken. Our data suggest that in chronically treated hypertensives AHM does not reduce the BP response to exercise.

Fitness Shifts the Balance of BDNF and IL-6 from Inflammation to Repair among People with Progressive Multiple Sclerosis.

Physical sedentarism is linked to elevated levels of circulating cytokines, whereas exercise upregulates growth-promoting proteins such as brain-derived neurotrophic factor (BDNF). The shift towards a ‘repair’ phenotype could protect against neurodegeneration, especially in diseases such as multiple sclerosis (MS). We investigated whether having higher fitness or participating in an acute bout of maximal exercise would shift the balance of BDNF and interleukin-6 (IL-6) in serum samples of people with progressive MS (n = 14), compared to matched controls (n = 8). Participants performed a maximal graded exercise test on a recumbent stepper, and blood samples were collected at rest and after the test. We assessed walking speed, fatigue, and maximal oxygen consumption (). People with MS achieved about 50% lower (p = 0.003) than controls. At rest, there were no differences in BDNF between MS and controls; however, IL-6 was significantly higher in MS. Higher was associated with a shift in BDNF/IL-6 ratio from inflammation to repair (R = 0.7, p = 0.001) when considering both groups together. In the MS group, greater ability to upregulate BDNF was associated with faster walking speed and lower vitality. We present evidence that higher fitness indicates a shift in the balance of blood biomarkers towards a repair phenotype in progressive MS.

The effects of vibration on efficiency in off-road cyclists.

Objectives The aim of this study was to investigate whether vibration significantly affected the efficiency of off-road cyclists. Patients and methods Eight male mountain cyclists (mean age 21.1±1 years; range, 19 to 22 years) between August 2017 and November 2017 were included. The experimental protocol included four testing sessions with a one-day interval between testing sessions: a familiarization session; performance of submaximal tests; performance of maximal graded exercise test; and a 30-min mountain bike trial performed with vibration or without vibration. Physiological measures including volume of oxygen uptake (VO2), volume of 2), VO2, VCO2, heart rate, respiratory exchange ratio, rating of perceived exertion, and gross efficiency (GE) were compared between the trials performed with vibration or without vibration. Results There was a significant increase in the GE with the addition of intermittent vibration, particularly over the last 15 min of the cycling trial (p<0.05). There were no significant effects of vibration on other parameters. Conclusion This study demonstrates that addition of intermittent vibration may provide positive benefits in improving GE during a 30-min submaximal cycling trial.

V̇ o2 peak Comparison of a Treadmill Vs. Cycling Protocol in Elite Teenage Competitive Runners, Cyclists, and Swimmers.

Marko, D, Bahenský, P, Snarr, RL, and Malátová, R. V̇ o2 peak Comparison of a treadmill vs. cycling protocol in elite teenage competitive runners, cyclists, and swimmers. J Strength Cond Res 36(10): 2875-2882, 2022-The purpose of this study was to compare the cardiorespiratory and metabolic responses of a maximal graded exercise test (GXT) on a treadmill and cycle ergometer in elite-level, youth competitive athletes. Thirty-one athletes (11 distance runners, 11 mountain-bike cyclists, and 9 long-distance swimmers) were randomly selected to complete either a running or cycling GXT on the first day, followed by the alternative 72 hours apart. The initial work rate for each GXT was set at 50% of the individuals' previously established V̇ o2 peak to elicit fatigue within 8-12 minutes. For the treadmill protocol, speed was increased by 1 km·h -1 each minute, with a constant 5% grade, until volitional fatigue. Cycle ergometer work rate was increased by 30 W every minute until volitional fatigue or the inability to maintain proper cadence (i.e., 100 ± 5 rev·min -1 ). Throughout both testing sessions, V̇ o2 peak, heart rate [HR] peak, breathing frequency (BF), tidal volume (V T ), and minute ventilation (V E ) were assessed and used to compare within-sport differences. Runners displayed a higher V̇ o2 peak (∼7%; d = 0.92), HRpeak (4%; d = 0.77), V E (6%; d = 0.66), and BF (12%; d = 0.62) on the treadmill vs. cycle. However, the cycling group demonstrated a greater V̇ o2 peak (∼8%; d = 0.92), V T (∼14%; d = 0.99), and V E (∼9%; d = 0.78) on the cycle, despite no change in HRpeak. For swimmers, the treadmill GXT elicited higher values in V̇ o2 peak (∼5%; d = 0.75), BF (∼11.5%; d = 0.78), and HRpeak (3%; d = 0.69). Collectively, these findings indicate that exercise mode may greatly affect physiological outcome variables and should be considered before exercise prescription and athletic monitoring.

Association of Objectively Measured Timing of Physical Activity Bouts With Cardiovascular Health in Type 2 Diabetes

Moderate- to vigorous-intensity physical activity (MVPA) improves cardiovascular health. Few studies have examined MVPA timing. We examined the associations of timing of bout-related MVPA with cardiorespiratory fitness and cardiovascular risk in adults with type 2 diabetes. Baseline 7-day hip-worn accelerometry data from Look AHEAD participants (n = 2,153, 57% women) were analyzed to identify bout-related MVPA (≥3 METs/min for ≥10 min). Cardiorespiratory fitness was assessed by maximal graded exercise test. Participants were categorized into six groups on the basis of the time of day with the majority of bout-related MVPA (METs × min): ≥50% of bout-related MVPA during the same time window (morning, midday, afternoon, or evening), <50% of bout-related MVPA in any time category (mixed; the reference group), and ≤1 day with bout-related MVPA per week (inactive). Cardiorespiratory fitness was highly associated with timing of bout-related MVPA (P = 0.0005), independent of weekly bout-related MVPA volume and intensity. Importantly, this association varied by sex (P = 0.02). In men, the midday group had the lowest fitness (β = -0.46 [95% CI -0.87, -0.06]), while the mixed group in women was the least fit. Framingham risk score (FRS) was associated with timing of bout-related MVPA (P = 0.02), which also differed by sex (P = 0.0007). The male morning group had the highest 4-year FRS (2.18% [0.70, 3.65]), but no association was observed in women. Timing of bout-related MVPA is associated with cardiorespiratory fitness and cardiovascular risk in men with type 2 diabetes, independent of bout-related MVPA volume and intensity. Prospective studies are needed to determine the impacts of MVPA timing on cardiovascular health.

Prediction of Simulated 1,000 m Kayak Ergometer Performance in Young Athletes.

This study aimed to develop a predictive explanatory model for the 1,000-m time-trial (TT) performance in young national-level kayakers, from biomechanical and physiological parameters assessed in a maximal graded exercise test (GXT). Twelve young male flat-water kayakers (age 16.1 ± 1.1 years) participated in the study. The design consisted of 2 exercise protocols, separated by 48 h, on a kayak ergometer. The first protocol consisted of a GXT starting at 8 km.h−1 with increments in speed of 1 km.h−1 at each 2-min interval until exhaustion. The second protocol comprised the 1,000-m TT.Results: In the GXT, they reached an absolute O2max of 3.5 ± 0.7 (L.min−1), a maximum aerobic power (MAP) of 138.5 ± 24.5 watts (W) and a maximum aerobic speed (MAS) of 12.8 ± 0.5 km/h. The TT had a mean duration of 292.3 ± 15 s, a power output of 132.6 ± 22.0 W and a O2max of 3.5 ± 0.6 (L.min−1). The regression model [TT (s) = 413.378–0.433 × (MAP)−0.554 × (stroke rate at MAP)] presented an R2 = 84.5%.Conclusion: It was found that O2max, stroke distance and stroke rate during the GXT were not different from the corresponding variables (O2peak, stroke distance and stroke rate) observed during the TT. The MAP and the corresponding stroke rate were strong predicting factors of 1,000 m TT performance. In conclusion, the TT can be useful for quantifying biomechanical parameters (stroke distance and stroke rate) and to monitor training induced changes in the cardiorespiratory fitness (O2max).

Effect of Aerobic Exercise on Cardiopulmonary Responses and Predictors of Change in Individuals With Parkinson's Disease

ObjectiveTo determine the effect of aerobic exercise on maximal and submaximal cardiopulmonary responses and predictors of change in individuals with Parkinson's disease (PD). DesignSingle-center, parallel-group, rater-blind study. SettingResearch laboratory. ParticipantsIndividuals with mild to moderate PD (N=100). InterventionParticipants were enrolled in a trial evaluating the effect of cycling on PD and randomized to either voluntary exercise (VE), forced exercise (FE), or a no exercise control group. The exercise groups were time and intensity matched and exercised 3×/wk for 8 weeks on a stationary cycle. Main Outcome MeasuresCardiopulmonary responses were collected via gas analysis during a maximal graded exercise test at baseline and post intervention. ResultsExercise attendance was 97% and 93% for the FE and VE group, respectively. Average exercise heart rate reserve was 67%±11% for FE and 70%±10% for VE. No significant difference was present for change in peak oxygen consumption (VO2peak) post intervention, even though the FE group had a 5% increase in VO2peak. Both the FE and VE groups had significantly higher percentage oxygen consumption per unit time (V˙o2) at ventilator threshold (VT) than the control group compared with baseline values (P=.04). Mean V˙O2 at VT was 5% (95% CI, 0.1%-11%) higher in the FE group (P=.04) and 7% (2%, 12%) higher in VE group compared with controls. A stepwise linear regression model revealed that lower age, higher exercise cadence, and lower baseline VO2peak were most predictive of improved VO2peak. The overall model was found to be significant (P<.01). ConclusionsPeak and submaximal cardiopulmonary function may improve after aerobic exercise in individuals with PD. Lower age, higher exercise cadence, and lower baseline VO2peak were most predictive of improved VO2peak in this exercise cohort. The improvements observed in aerobic capacity were gained after a relatively short aerobic cycling intervention.

Development of multistage 10-m shuttle run test for VO2max estimation in healthy adults

Background and objective: The disadvantage of the traditional 20-m multistage shuttle run test (MST) is that it requires a long space for measurements and does not include various age groups to develop the test. Therefore, we developed a new MST to improve the spatial limitation by reducing the measurement to a 10-m distance and to resolve the bias via uniform distributions of gender and age. Material and methods: Study subjects included 120 healthy adults (60 males and 60 females) aged 20 to 50 years. All subjects performed a graded maximal exercise test (GXT) and a 10-m MST at five-day intervals. We developed a regression model using 70% of the subject's data and performed a cross-validation test using 30% of the data. Results: The male regression model's coefficient of determination (R2) was 58.8%, and the standard error of estimation (SEE) was 4.17 mL/kg/min. The female regression model's R2 was 69.2%, and the SEE was 3.39 mL/kg/min. The 10-m MST showed a high correlation with GXT on the VO2max (males: 0.816; females: 0.821). In the cross-validation test for the developed regression models, the male's SEE was 4.38 mL/kg/min, and the female's SEE was 4.56 mL/kg/min. Conclusion: Thus, the 10-m MST is an accurate and valid method for estimating the VO2max. Therefore, the 10-m MST developed by us can be used when the existing 20-m MST cannot be used due to spatial limitations and can be applied to both men and women in their 20s and 50s.