Graded Treadmill Exercise Test Research Articles

Cardiorespiratory Fitness Modifies the Association of Cerebral Pulsatility on CSF Biomarkers Related to Neurodegeneration, Synaptic Dysfunction, and Neuroinflammation

AbstractBackgroundCerebral pulsatility (PI) is reportedly higher in individuals with AD and MCI compared to age matched controls and has been associated with greater beta‐amyloid (Aß) burden, but its relationship to other neurodegenerative biomarkers is unknown. Higher cardiorespiratory fitness (CRF) positively affects vascular function and is associated with lower PI in several large cerebral vessels. The relationship between PI, CRF, and biomarkers for neurodegeneration have not yet been characterized. Our objective was to examine a potential CRF modification of the relationship between PI and cerebrospinal fluid (CSF) biomarkers of neurodegeneration, synaptic dysfunction, and neuroinflammation.MethodsCognitively unimpaired adults (n=32, Mean Age=64) from the Wisconsin Registry for Alzheimer's Prevention and the Wisconsin Alzheimer's Disease Research Center who met selection criteria were included. PI from bilateral MCA vessels were measured using 4D flow MRI and averaged (PI‐MCAAVG). CRF was measured as peak VO2PEAK during a graded exercise treadmill test. CSF was obtained via lumbar puncture and measured using the NeuroToolKit, a panel of robust prototype assays (Roche Diagnostics International Ltd). The toolkit included measures of: neurodegeneration [α‐synuclein (α‐syn) and neurofilament light polypeptide (NfL)], synaptic dysfunction [neurogranin (Ng), synaptosomal‐associated protein 5 (SNAP‐25), and neuronal activity related protein 2 (nptx2)], and neuroinflammation [glial fibrillary acidic protein (GFAP), soluble triggering receptor expressed in myeloid cells (sTREM2), and chitinase‐3‐like protein 1 (YKL‐40)]. A single multivariate regression model, adjusted for sex, age, and APOE4, examined whether the association between PI‐MCAAVG and CSF biomarkers varied as a function of CRF.ResultsThere was a significant interaction between PI and VO2PEAK on α‐syn (ß = ‐22.66, p=0.04), Ng (ß =‐171.46, p=0.01), SNAP‐25 (ß = ‐0.35, p= 0.02), STREM2 (ß =‐1.04, p=0.02), and nptx2 (ß =‐1037, p=0.04) indicating more favorable profiles of CSF biomarkers with increasing VO2PEAK despite elevated PI. No significant interactions were found for NfL, GFAP, or YKL40 (all p’s > 0.05).ConclusionOur findings support the hypothesis that increased CRF influences the relationship between cerebral PI and CSF biomarkers related to neurodegeneration, synaptic dysfunction, and neuroinflammation indicating that improved CRF may offer protection against cerebrovascular alterations known to coincide with biomolecular changes in various types of dementia.

Cardiorespiratory Fitness Modifies the Association Between Cerebral Pulsatility on Amyloid Burden and Core CSF Biomarkers of Alzheimer’s Disease

AbstractBackgroundIncreasing evidence supports the notion that vascular dysfunction contributes to the evolution of Alzheimer’s disease (AD). Cerebral pulsatility index (PI) is reportedly higher in AD and MCI compared to age matched controls and has been associated with greater beta‐amyloid (Aß) burden. Higher cardiorespiratory fitness (CRF) positively affects vascular function and is associated with lower PI in several large cerebral vessels. Our objective was to examine whether CRF modifies the relationship between PI, Aß burden, and core AD cerebrospinal fluid (CSF) biomarkers.MethodCognitively unimpaired adults (n=33, MeanAGE=64.0) from the Wisconsin Registry for Alzheimer's Prevention and the Wisconsin Alzheimer's Disease Research Center who met study criteria were included. Aß burden was measured as global cortical PiB‐PET. CSF biomarkers were measured with the NeuroTookKit, a panel of robust prototype assays (Roche Diagnostics International Ltd). PI from bilateral MCA vessels were measured using 4D flow MRI and averaged (PI‐MCAAVG). CRF was indexed as VO2peak during a graded exercise treadmill test. A single multivariate regression, (covariate‐adjusted for sex, age, and APOE4) examined whether CRF modifies the impact of PI‐MCAAVG on Aß burden and core‐AD CSF biomarkers [phosphorylated Tau 217 (pTau‐217), total Tau (tTau), Aß42/Aß40, pTau/Aß42]. When significant, the PI*CRF interaction term would indicate a differential effect of PI on Aß burden or CSF biomarker as a function of CRF.ResultThere was a significant interaction between PI and VO2peak on PET Aß burden (ß = ‐0.05, p= 0.04), Aß42/ Aß40 (ß=0.006, p=0.03), pTau (ß= ‐3.4, p=0.03), tTau (ß ‐29.8, p=0.04) and pTau/Aß42 (ß= ‐0.006, p=0.02), indicating less Aß burden and more favorable profiles for all core CSF biomarkers with increasing VO2peak despite elevated PI.ConclusionOur findings support the hypothesis that greater CRF modifies the effect of cerebral PI on PET Aß burden and core AD CSF biomarkers, indicating that improved VO2 seems to be protective against cerebrovascular alterations known to contribute to AD‐related biomolecular changes.

Characterization of a novel ovine model of hypertensive heart failure with preserved ejection fraction.

The lack of animal models that accurately represent heart failure with preserved ejection fraction (HFpEF) has been a major barrier to the mechanistic understanding and development of effective therapies for this prevalent and debilitating syndrome characterized by multisystem impairments. Herein, we describe the development and characterization of a novel large animal model of HFpEF in older, female sheep with chronic 2-kidney, 1-clip hypertension. At 6-wk post unilateral renal artery clipping, hypertensive HFpEF sheep had higher mean arterial pressure compared with similarly aged ewes without unilateral renal artery clipping (mean arterial pressure = 112.7 ± 15.9 vs. 76.0 ± 10.1 mmHg, P < 0.0001). The hypertensive HFpEF sheep were characterized by 1) echocardiographic evidence of diastolic dysfunction (lateral e' = 0.11 ± 0.02 vs. 0.14 ± 0.04 m/s, P = 0.011; lateral E/e' = 4.25 ± 0.77 vs. 3.63 ± 0.54, P = 0.028) and concentric left ventricular hypertrophy without overt systolic impairment, 2) elevated directly measured left ventricular end-diastolic pressure (13 ± 5 vs. 0.5 ± 1 mmHg, P = 2.1 × 10-6), and 3) normal directly measured cardiac output. Crucially, these hypertensive HFpEF sheep had impaired exercise capacity as demonstrated by their 1) attenuated cardiac output (P = 0.001), 2) augmented pulmonary capillary wedge pressure (P = 0.026), and 3) attenuated hindlimb blood flow (P = 3.4 × 10-4) responses, during graded treadmill exercise testing. In addition, exercise renal blood flow responses were also altered. Collectively, our data indicates that this novel ovine model of HFpEF may be a useful translational research tool because it exhibits similar and clinically relevant impairments as that of patients with HFpEF.NEW & NOTEWORTHY We show that older, female sheep with chronic 2-kidney, 1-clip hypertension have similar cardiac and noncardiac exercise hemodynamic abnormalities as patients with HFpEF. This clinically relevant, translatable, and novel large animal model of HFpEF may be useful for elucidating mechanisms and developing treatments for this increasingly common syndrome with few clinically impactful therapies.

Safety and efficacy of adaptive atrial pacing regulated by blood pressure during low-level exercise: a proof-of-concept study.

Despite half of all heart failure patients suffering from heart failure with preserved ejection fraction (HFpEF), treatment options are limited. This study aims to compare safety and efficacy of standard pacemaker programming (DDD or DDDR) and a novel pacing algorithm PressurePace™ (BaroPace Inc, Issaquah, WA, USA) which modulates atrial pacing rate based on blood pressure (BPAP). This prospective, randomized, double-blind, non-significant risk proof of concept study was conducted at two large cardiology clinics in Los Angeles, California, USA. Subjects underwent two modified Bruce protocol graded treadmill exercise tests in which pacemaker programming was randomized to either standard programming (DDD or DDDR), or BPAP at least 1week apart. Physiological measurements of heart rate (HR), and systolic and diastolic blood pressure (BP) were collected at 2min intervals. During the BPAP treadmill test, the pacemaker activity sensor was disabled. The PressurePace algorithm instructed the pacemaker technician to modify or leave unchanged the atrial pacing rate based on these BP measurements. Subjects and clinical staff were blinded to pacemaker programming, only the pacemaker technician was unblinded. Ten subjects with HFpEF associated with hypertension who also had permanent dual-chamber pacemakers, previously implanted for standard clinical indications, participated in the study. Mean age was 70.1±6.8 years, left ventricular ejection fraction of 54.8±1.9%. Exercise duration increased in all 10 subjects, when paced in the BPAP mode compared with standard pacemaker programming, showing a mean increase of 117s (26%, P=0.0016). The algorithm could adjust HR at each 2min interval. The majority of subjects (60%) had their atrial pacing rate increased an average of 20% at t=2min. In the remaining 40% of subjects, the algorithm instructed HR to be unchanged. In two subjects, the pacing rate was not increased until t=6min. In contrast, subjects programmed to DDDR experienced an average of 45% increase in atrial pacing rate at t=2min. In the post-treadmill recovery period, SBP was higher for subjects who underwent BPAP. This difference in SBP was most pronounced immediately post-treadmill and diminished as subjects progressed through the 30min recovery period. Statistical significance was achieved at t=0, 20, and 30min post-treadmill. An increase in exercise duration was reported in HFpEF subjects using a pacing algorithm that modulated HR based on BP compared with standard programming. These encouraging results form the basis for a larger, randomized cross-over trial to confirm these initial observations, further characterize the safety, efficacy, and possible mechanisms of action in both acute and longer-term treatment.

High-intensity exercise training using a rotarod instrument (RotaHIIT)significantly improves exercise capacity in mice.

Voluntary or forced exercise training in mice is used to assess functional capacity as well as potential disease-modifying effects of exercise over a range of cardiovascular disease phenotypes. Compared to voluntary wheel running, forced exercise training enables precise control of exercise workload and volume, and results in superior changes in cardiovascular performance. However, the use of a shock grid with treadmill-based training is associated with stress and risk of injury, and declining compliance with longer periods of training time for many mouse strains. With these limitations in mind, we designed a novel, high-intensity interval training modality (HIIT) for mice that is carried out on a rotarod. Abbreviated as RotaHIIT, this protocol establishes interval workload intensities that are not time or resource intensive, maintains excellent training compliance over time, and results in improved exercise capacity independent of sex when measured by treadmill graded exercise testing (GXT) and rotarod specific acceleration and endurance testing. This protocol may therefore be useful and easily implemented for a broad range of research investigations. As RotaHIIT training was not associated cardiac structural or functional changes, or changes in oxidative capacity in cardiac or skeletal muscle tissue, further studies will be needed to define the physiological adaptations and molecular transducers that are driving the training effect of this exercise modality.

Effects of a 10-Week Exercise and Nutritional Intervention with Variable Dietary Carbohydrates and Glycaemic Indices on Substrate Metabolism, Glycogen Storage, and Endurance Performance in Men: A Randomized Controlled Trial.

Daily nutrition plays an important role in supporting training adaptions and endurance performance. The objective of this 10-week study was to investigate the consequences of varying carbohydrate consumption and the glycaemic index (GI) together with an endurance training regimen on substrate oxidation, muscle energy storage and endurance performance under free-living conditions. Sixty-five moderately trained healthy men (29 ± 4years; VO2 peak 55 ± 8mLmin-1kg-1) were randomized to one of three different nutritional regimes (LOW-GI: 50-60% CHO with ≥ 65% of these CHO with GI < 50 per day, n = 24; HIGH-GI: 50-60% CHO with ≥ 65% CHO with GI > 70 per day, n = 20; LCHF: ≤ 50g CHO daily, n = 21). Metabolic alterations and performance were assessed at baseline (T0) and after 10weeks (T10) during a graded exercise treadmill test. Additionally, a 5km time trial on a 400-m outdoor track was performed and muscle glycogen was measured by magnet resonance spectroscopy. Total fat oxidation expressed as area under the curve (AUC) during the graded exercise test increased in LCHF (1.3 ± 2.4gmin-1 × kmh-1, p < 0.001), remained unchanged in LOW-GI (p > 0.05) and decreased in HIGH-GI (- 1.7 ± 1.5gmin-1 × kmh-1, p < 0.001). After the intervention, LOW-GI (- 0.4 ± 0.5mmol L-1 × kmh-1, p < 0.001) and LCHF (- 0.8 ± 0.7mmolL-1 × kmh-1, p < 0.001) showed significantly lower AUC of blood lactate concentrations. Peak running speed increased in LOW-GI (T0: 4.3 ± 0.4 vs. T10: 4.5 ± 0.3ms-1, p < 0.001) and HIGH-GI (T0: 4.4 ± 0.5 vs. T10: 4.6 ± 0.4ms-1), while no improvement was observed in LCHF. Yet, time trial performance improved significantly in all groups. Muscle glycogen content increased for participants in HIGH-GI (T0: 97.3 ± 18.5 vs. T10: 144.5 ± 39.8mmol L wet-tissue-1, p = 0.027) and remained unchanged in the LOW-GI and the LCHF group. At the last examination, muscle glycogen concentration was significantly higher in LOW-GI compared to LCHF (p = 0.014). Changes in fat oxidation were only present in LCHF, however, lower lactate concentrations in LOW-GI resulted in changes indicating an improved substrate metabolism. Compared to a LCHF diet, changes in peak running speed, and muscle glycogen stores were superior in LOW- and HIGH-GI diets. The low GI diet seems to have an influence on substrate metabolism without compromising performance at higher intensities, suggesting that a high-carbohydrate diet with a low GI is a viable alternative to a LCHF or a high GI diet. Clinical Trials, NCT05241730. https://clinicaltrials.gov/study/NCT05241730 . Registered 25 January 2021.

Association of postexercise blood pressure with cardiovascular outcomes and mortality: The CARDIA study.

Postexercise blood pressure (BP) may be a better predictor of cardiovascular risk than office BP, but there is a lack of data supporting this claim. We hypothesized that postexercise BP may be an important prognostic marker. Our aim was to evaluate the association of postexercise BP with major adverse cardiovascular events (MACE) and all-cause mortality. A total of 2581 participants (median age, 46 years; 55.9% women) from the Coronary Artery Risk Development in Young Adults study at year 20 (2005-2006) who underwent a graded exercise treadmill test using a modified Balke graded protocol were included. Postexercise BP was measured at baseline. Cox models were used to estimate the associations of postexercise BP with MACE and all-cause mortality. Participants were followed up until December 31, 2021. In the entire population, postexercise systolic BP showed no significant association with MACE or all-cause mortality, while postexercise diastolic BP was associated with MACE (hazard ratios [HR], 1.27 [95% CI, 1.06-1.52], per 10mmHg increase) and all-cause mortality (HR, 1.26 [95% CI, 1.05-1.51], per 10mmHg increase). In the normal BP group, postexercise systolic BP was not significantly associated with MACE or all-cause mortality, and postexercise diastolic BP was strongly associated with MACE (HR, 1.57 [95% CI, 1.18-2.09], per 10mmHg increase). In this population-based cohort study, postexercise diastolic BP was significantly associated with the risk of MACE and all-cause mortality. Among individuals with normal BP, postexercise diastolic BP could identify those at a higher risk of cardiovascular events.

ARE CHANGE IN METS DURING CARDIAC REHAB RELATED TO CHANGE IN PEAK VO2 AND 6MWD?

https://youtu.be/x7wTd1TmxrA BACKGROUND Change in metabolic equivalents of task (METs) during exercise training is often used as a program outcome in cardiac rehabilitation (CR). The purpose of this study is to assess the correlation between the change in estimated exercise training METs during a CR program and the change in six-minute walk distance (6MWD) and change in peak oxygen uptake (VO2). METHODS This is a secondary analysis of data from the iATTEND trial- a randomized controlled trial that compared facility based CR versus hybrid CR. Subjects included in this analysis had a history of myocardial infraction, coronary revascularization, heart failure, or valve surgery and completed ≥12 sessions of CR. METs during exercise training were estimated using ACSM treadmill equations from the average of the second, third and fourth sessions of CR and the final three sessions of CR. 6MWD and peak VO2 was derived from a symptom limited graded exercise treadmill test with gas exchange were collected at baseline before starting CR and within 14 days of completing CR. Pearson correlation coefficient was determined between change in estimated exercise training METs and both change in 6MWD and in peak VO2. RESULTS The final cohort was n=237 (age=59±12 years; 35% women; 57% non-white race). The correlation between change in estimated exercise training METs and 6MWD was r=0.257, r=0.245, and r=0.235 among patients who completed ≥12 sessions of CR, ≥24 sessions of CR, and 36 sessions of CR, respectively. The correlation between change in estimated exercise training METs and peak VO2 was r=0.121, r=0.100, and r=0.136 among patients who completed ≥12 sessions of CR, ≥24 sessions of CR, and 36 sessions of CR, respectively. CONCLUSIONS Although change in estimated exercise training METs during a CR program, change in 6MWD, and change in peak VO2 have each been used to describe change in exercise tolerance for program outcomes, the association between these variables is low (r= &amp;lt;0.3). This finding was independent regardless of the number of sessions completed. Further research is needed to better understand the relationship between the various methods of assessing change in exercise tolerance and program outcomes in CR.

RELATIVE AND ABSOLUTE METABOLIC COST OF DAILY PHYSICAL ACTIVITIES ACROSS THE LIFESPAN

Abstract Americans spend over 90% of their activity related energy expenditure performing common daily activities. However, there is a gap in knowledge pertaining to potential age-related differences in the metabolic cost of performing these activities which diminishes proper physical activity prescription. We hypothesized age differences in both the absolute and relative metabolic cost of performing common daily physical. Participants (n=248, age: 20-94 yrs) performed 33 activities (e.g. dressing, walking, making a bed, gardening, computer work) in a standardized setting. A portable indirect calorimeter was worn for approximately 6-10 minutes to achieve steady-state metabolic rate. A graded exercise treadmill test was performed to quantify peak metabolic rate. A metabolic equivalent (MET as a function of 3.5 milliliter•min-1•kg-1) and percentage of peak were used to express absolute and relative metabolic rate, respectively. Watching television (1.0+/-0.36 METs; 15.6+/-5.7% of peak) produced the lowest and climbing stairs (6.2+/-2.2 METs; 84.8+/-17.0% of peak) elicited the highest metabolic rate. Results from mixed effect regression models adjusting for health conditions, demographics and anthropometry showed no association between absolute MET and age. However, when expressed relative to peak, adjusted models showed a strong association with age (0.66+/-0.33% per year, p=0.006). As an example, adults &amp;lt; 40 yrs old worked at 34.1+/-14.8% of peak during a leisurely walk while those 80+ years old worked at 64.2+/-16.3%. Aging is associated with a substantial increase in the relative metabolic cost of performing common daily physical activities. These results could have implications on prescribing physical activity older adults to achieve higher fitness.

Influence of Cardiorespiratory Fitness on Cardiac Autonomic Recovery Among Active-Duty Firefighters.

Abstract Cornell, DJ, Flees, RJ, Shemelya, CM, and Ebersole, KT. Influence of cardiorespiratory fitness on cardiac autonomic recovery among active-duty firefighters. J Strength Cond Res 38(1): 66–73, 2024—It has been suggested that an inability of the autonomic nervous system (ANS) to recover after strenuous events is a potential cause of sudden cardiac death among firefighters. The purpose of this study was to examine the influence of cardiorespiratory fitness (CRF) on the heart rate recovery (HRR) kinetics of firefighters. Thirty-seven male career active-duty firefighters completed both a submaximal step test and a maximal treadmill graded exercise test. A monoexponential curve was fit to postexercise submaximal and maximal HRR data of each subject. Subjects were placed into Low CRF (n = 13) and High CRF (n = 24) groups based on the standard peak aerobic capacity (V̇O2peak) criterion of &lt;42 ml·kg−1·minute−1 and ≥42 ml·kg−1·minute−1, respectively. After controlling for age and body mass index, CRF was significantly (p &lt; 0.05) correlated with the decay rate ( ) and asymptote ( ) after submaximal exercise (r sp = −0.556; r sp = −0.637, respectively), as well as the , , and amplitude ( ) after maximal exercise (r sp = −0.353; r sp = −0.416; r sp = 0.603, respectively). High CRF firefighters demonstrated a significantly faster after both submaximal (p = 0.003) and maximal exercise (p = 0.043), a lower after submaximal exercise (p = 0.002), and a higher after maximal exercise (p = 0.001), than Low CRF firefighters. Greater CRF was associated with enhanced HRR kinetics after submaximal and maximal exertion, suggesting that CRF may positively influence the ANS recovery of firefighters.

Higher training loads affect sleep in endurance runners: Can a high-heat-capacity mattress topper mitigate negative effects?

ABSTRACT This study investigates the impact of a training program on sleep among endurance runners and the benefits of chronically using a high-heat-capacity mattress topper (HMT). Twenty-one trained male athletes performed a 2-week usual training regimen, sleeping on a Low-heat-capacity Mattress Topper (LMT), followed by 2-week overload and taper periods. From overload, participants were assigned into two groups based on the mattress topper used: HMT (n = 11) or LMT (n = 10). Irrespective of the group, overload increased general stress and stress-reaction symptoms evaluated by questionnaires, with no decline in performance on a graded-exercise treadmill test, the majority of participant being “non-overreached” (n = 14). From a daily perspective, each additional 100 A.U. in training load, assessed using the session rating of perceived exertion, was associated with an impairment in subsequent sleep efficiency (β = -0.2%; p < 0.01), wake after sleep onset (β = +0.4 min; p < 0.05) and sleep onset latency (β = +0.5 min; p < 0.05), which was unaffected by HMT use. Practitioners should be aware of sleep needs, especially during excessive training loads, whereas implementing individualised sleep strategies. Further studies should be conducted on potential benefits of HMT among athletes in various sleep conditions.

The efficacy of a verification stage for determining O2max and the impact of sampling intervals.

It is unknown whether oxygen uptake (V̇O2) sampling intervals influence the efficacy of a verification stage following a graded exercise test (GXT). Fifteen females and 14 males (18-25 years) completed a maximal treadmill GXT. After a 5​min recovery, the verification stage began at the speed and grade corresponding with the penultimate stage from the GXT. Maximal oxygen consumption (V̇O2max) from the incremental GXT (iV̇O2max) and V̇O2max from the verification stage (verV̇O2max) were determined using 10 seconds (s), 30​s, and 60​s from breath​×​breath averages. There was no main effect for V̇O2max measure (iV̇O2maxvs. verV̇O2max) 10​s ([47.9​±​8.31] ml∙kg-1∙min-1 vs [48.85​±​7.97] ml∙kg-1∙min-1), 30​s ([46.94​±​8.62] ml∙kg-1∙min-1 vs [47.28​±​7.97] ml∙kg-1∙min-1), and 60​s ([46.17​±​8.62] ml∙kg-1∙min-1 vs [46.00​±​8.00] ml∙kg-1∙min-1]. There was a stage​×​sampling interval interaction as the difference between (verV̇O2max-iV̇O2max) was greater for 10-s than 60-s sampling intervals. The verV̇O2max was > 4% higher than iV̇O2maxin 31%, 31%, and 17% of the tests for the 10-s, 30-s, and 60-s sampling intervals respectively. Sensitivity for the plateau was < 30% for 10-s, 30-s, and 60-s sampling intervals. Specificity ranged from 44% to 60% for all sampling intervals. Sensitivity for heart rate​+​respiratory exchange ratio was > 90% for all sampling intervals; while specificity was < 25%. Findings from the present study suggest that the efficacy of verification stages for eliciting a higher V̇O2max may be influenced by the sampling interval utilized.

A 3-minute recumbent stepper test in chronic stroke.

Persons with stroke often have difficulty achieving target heart rate (HR) during graded exercise testing (GXT), which is known to limit test sensitivity for detecting clinically relevant cardiac conditions. A novel Recumbent Stepper 3-minute (RS 3Min) "all out" test may increase sensitivity of stress testing after stroke. To determine the feasibility of adding the RS 3Min test after GXT among persons after stroke. A within-participant, nonrandomized, repeated measures design. Rehabilitation research laboratory and cardiovascular stress laboratory PARTICIPANTS: Fifteen participants with chronic stroke (56.7 ± 9.6 years; 6.4 ± 4.3 years post stroke; 8 male). All participants randomly completed (1) a symptom-limited treadmill GXT and (2) a symptom-limited RS GXT followed by RS 3Min critical power test. HR, ratings of perceived exertion, oxygen consumption, respiratory exchange ratio, and power output measured continuously during each test. Blood pressure measured every 2 minutes and or immediately post exercise. P value set at p < .05 from omnibus test for a significant difference among protocols. The RS 3Min test had a significantly higher rate of achieving target HR compared to the RS GXT (9/14 vs 4/14, p=.02) and was not significantly different from the treadmill GXT (9/14 vs 5/14, p=.09). Minimum power output during the RS 3Min was significantly higher than peak power output during the RS GXT (110 ± 41 W vs. 84 ± 22 W, p=.02) with 12/15 participants reaching a VO2 plateau. Although additional studies with randomized designs are needed, a novel RS 3Min "all out" test appears to be a promising method for enhancing test sensitivity in cardiovascular screening after stroke, while providing a potentially valid measure of critical power.

Methodological considerations for the determination of VO2max in healthy men.

A square-wave verification bout to confirm maximal oxygen uptake ([Formula: see text]O2max) from a graded exercise test (GXT) has been recommended. This study ascertained if a verification bout is necessary to determine [Formula: see text]O2max in moderately trained men. Ten men (24 ± 4years) completed familiarization and two treadmill GXTs, followed by a submaximal verification bout to determine [Formula: see text]O2GXT and [Formula: see text]O2verification (highest [Formula: see text]O2 from each testing method). After completing the GXT, subjects rested for 5min then performed a verification bout at 90% speed and 50% incline at termination of the GXT. The analyses included a 2-way repeated-measures ANOVA, intra-class correlation coefficients (ICC2,1), standard errors of the measurement (SEM), minimal differences (MD), and coefficients of variation (CoV). There was no test (test 1 vs test 2) × method (GXT vs verification) interaction (p = 0.584), or main effect for test (p = 0.320), but there was a main effect for method (p = 0.011). The [Formula: see text]O2GXT (50.9±3.0mL·kg-1·min-1) was greater than [Formula: see text]O2verification (46.9 ± mL·kg-1·min-1). The [Formula: see text]O2GXT (ICC = 0.988, SEM = 1.0mL·kg-1 min-1, MD = 2.9mL kg-1 min-1, CoV = 2.03%) and [Formula: see text]O2verification (ICC = 0.976, SEM = 1.0mL·kg-1 min-1, MD = 2.7mL·kg-1·min-1, CoV = 2.03%) demonstrated "excellent" reliability. No subject exceeded the MD for [Formula: see text]O2GXT test-retest or for [Formula: see text]O2verification test-retest, but 50% of subjects had a [Formula: see text]O2GXT that was greater than the [Formula: see text]O2verification (> MD). While [Formula: see text]O2GXT and [Formula: see text]O2verification demonstrated excellent reliability, [Formula: see text]O2GXT from a stand-alone GXT provided higher estimates of [Formula: see text]O2 and, therefore, should be considered [Formula: see text]O2max. The lack of test-retest differences in [Formula: see text]O2GXT above the MD indicated that subjects achieved their highest [Formula: see text]O2 ([Formula: see text]O2max) from a standalone GXT. Therefore, the verification bout may not be required to confirm [Formula: see text]O2max in this population.

Association between the empirical dietary inflammatory index and cardiorespiratory fitness in Tehranian adults in 2017-2018.

BackgroundInflammatory-related chronic diseases are increasing in Iran with high consumption of a diet containing pro-inflammatory potential and a sedentary lifestyle. The empirical dietary inflammatory index (EDII) was developed as a tool to assess dietary effects on systemic inflammation. We examined the hypothesis that specific dietary patterns reflecting systemic inflammation are associated with cardiorespiratory fitness (CRF) in Tehranian adults.MethodsThis cross-sectional study was carried out on 270 adults who are residents of Tehran. Dietary intake was assessed using a 168-item valid and reliable food frequency questionnaire. The EDII score was developed according to participant dietary intakes of 21-item pre-defined food groups. CRF was assessed by using a graded exercise treadmill test. Anthropometric measurements were assessed using standard methods. To discover the association between CRF and EDII, we used multivariable logistic regression analysis.ResultsThose who were in the third tertile of the EDII had 57% lower odds of having better VO2Max (ml/kg/min) than those in the first tertile (OR: 0.43; 95% CI: 0.16, 1.12, p = 0.01). There were no significant differences between tertiles of the EDII score in terms of VO2 (L·min) and VO2 (LBM) before and after adjusting for confounders. There was a significant decrease in VO2Max (ml/kg/min) across tertiles of the EDII after controlling for covariates (p-value = 0.04). There was a significant inverse association between the EDII score and VO2Max (ml/kg/min) (β = −0.35, p = 0.001).ConclusionsOur finding demonstrated that a higher EDII might be associated with lower CRF in Tehranian adults. Prospective studies are needed to shed light on the causal link between the EDII and CRF.

Effect Of Moderate- And Vigorous-intensity Aerobic And Anaerobic Exercise On A Woman With Post-covid-19 Syndrome

Individuals with post-COVID-19 syndrome (long COVID) are subject to a variety of persistent symptoms including sporadic bouts of dyspnea. Both aerobic and anaerobic exercise modalities are effective treatments for the management of other chronic respiratory diseases, but exercise tolerance or benefits in long COVID remains unclear. PURPOSE: The purpose of this case study was to determine if exercise of various intensities and modalities triggered dyspneic episodes in a person with long COVID. METHODS: A woman (44 yrs; 73 kg; BMI 24.4 kg·m-2; resting peripheral blood oxygen saturation (SpO2) 98%) who was infected with COVID-19 in November 2020 followed by persistent and unpredictable bouts of significant dyspnea was tested 8 months post-infection. All tests were performed on the same day and included a graded exercise treadmill test (GXT) at habitual walking speed (1.34 m·sec-1) with an increasing grade of 2% per minute, a 6-min treadmill walking tests at 60% and 80% peak heart rate (HR), one-repetition maximum (1RM) seated leg press, and 8-repetition leg press sets at 50%, 60%, 70%, and 80% 1RM. The order of testing (post-test rest period) were: GXT (10 min); 60% walking (10 min); 80% walking (10 min); 1RM determination (3 min); 50% 1RM, 60% 1RM, 70% 1RM, 80% 1RM (3 min between sets). SpO2 was captured via fingertip pulse oximeter, dyspnea was assessed by the Modified Borg Dyspnea Scale (Borg), and HR was captured using a chest-strap HR monitor. RESULTS: During all aerobic tests the participant maintained normal oxygen saturation (SpO2 range: 95-98%, greatest desaturation during 60% walking at minutes 2 & 6) and did not reach 5 (severe dyspnea) on the Borg (range: 0.5-4, highest rating at peak GXT). Similar results were seen during anaerobic testing (SpO2 range 98-99%, greatest desaturation at 50% & 60% 1RM sets; Borg range 0.5-3, highest rating post-80% 1RM set). CONCLUSION: Acute bouts of moderate- and vigorous-intensity aerobic or anaerobic exercise did not trigger severe dyspnea in a participant with long COVID prone to episodes of breathlessness. These results suggest that research using moderate or vigorous aerobic or strength training may be feasible for individuals with long COVID to determine whether training adaptation can be safely induced, as seen in other cohorts with chronic respiratory disease.

Effect of Long-term Exercise Training on Physical Performance and Cardiorespiratory Function in Adults With CKD: A Randomized Controlled Trial

The safety and efficacy of long-term exercise training in reducing physical functional loss in older adults with advanced CKD and comorbidity is uncertain. Multicenter, parallel group, randomized controlled trial. Adults 55 years and older with estimated glomerular filtration rate (eGFR) of 15 to<45 mL/min/1.73 m2 enrolled from centers in Baltimore and Boston. Twelve months of in-center supervised exercise training incorporating majority aerobic but also muscle strengthening activities or a group health education control intervention, randomly assigned in 1:1 ratio. Primary outcomes were cardiorespiratory fitness and submaximal gait at 6 and 12 months quantified by peak oxygen consumption (Vo2peak) on graded exercise treadmill test and distance walked on the 6-minute walk test, respectively. Secondary outcomes were changes in lower extremity function, eGFR, albuminuria, glycemia, blood pressure, and body mass index. Among 99 participants, the mean age was 68 years, 62% were African American, and the mean eGFR was 33 mL/min/1.73 m2; 59% had diabetes, and 29% had coronary artery disease. Among those randomized to exercise, 59% of exercise sessions were attended in the initial 6 months. Exercise was well tolerated without excess occurrence of adverse events. At 6 months, aerobic capacity was higher among exercise participants (17.9 ± 5.5 vs 15.9 ± 7.0 mL/kg/min, P= 0.03), but the differences were not sustained at 12 months. The 6-minute walk distance improved more in the exercise group (adjusted difference: 98 feet [P= 0.02; P= 0.03 for treatment-by-time interaction]). The exercise group had greater improvements on the Timed Up and Go Test (P= 0.04) but not the Short Physical Performance Battery (P= 0.8). Planned sample size was not reached. Loss to follow-up and dropout were greater than anticipated. Among adults aged≥55 years with CKD stages 3b-4 and a high level of medical comorbidity, a 12-month program of in-center aerobic and resistance exercise training was safe and associated with improvements in physical functioning. Government grants (National Institutes of Health). Registered at ClinicalTrials.gov with study number NCT01462097.

Associations between heart rate variability and maximal fat oxidation in two different cohorts of healthy sedentary adults

Background and aimsResting heart rate variability (HRV) and maximal fat oxidation (MFO) during exercise are both considered as a noninvasive biomarkers for early detection of cardiovascular risk factors. Thus, this study aimed to analyze the relationship between resting HRV parameters and MFO during exercise, and the intensity of exercise that elicit MFO (Fatmax) in healthy sedentary adults. Methods and resultsA total of 103 healthy young adults (22.2 ± 2.3 years old, 67% female; from the ACTIBATE cohort) and 67 healthy middle-aged adults (53.1 ± 5.0 years old, 52% female; from the FIT-AGEING cohort) were included in this cross-sectional study. HRV was assessed using a Polar RS800CX heart rate monitor, while MFO and Fatmax were determined during a graded exercise treadmill test using indirect calorimetry. No significant associations were observed for healthy young adults (standardized β coefficients ranged from −0.063 to 0.094, and all P ≥ 0.347) and for middle-aged adults (standardized β coefficients ranged from −0.234 to 0.090, and all P ≥ 0.056). Nevertheless, only a weak association was observed between one HRV parameter in time-domain (the percentage of R-R intervals that shows a difference higher than 50 ms [pNN50]) and MFO in the cohort of middle-aged adults (β coefficient = −0.279, and P = 0.033). ConclusionThe results of this study suggest that resting HRV parameters are not associated with MFO and Fatmax during exercise in two independent cohorts of healthy sedentary young and middle-aged adults, respectively.

Effect of Cloth Masks and N95 Respirators on Maximal Exercise Performance in Collegiate Athletes.

This study compared exercise performance and comfort while wearing an N95 filtering facepiece respirator (N95), cloth mask, or no intervention control for source control during a maximal graded treadmill exercise test (GXT). Twelve Division 1 athletes (50% female, age = 20.1 ± 1.2, BMI = 23.5 ± 1.6) completed GXTs under three randomized conditions (N95, cloth mask, control). GXT duration, heart rate (HR), respiration rate (RR), transcutaneous oxygen saturation (SpO2), transcutaneous carbon dioxide (TcPCO2), rating of perceived exertion (RPE), and perceived comfort were measured. Participants ran significantly longer in control (26.06 min) versus N95 (24.20 min, p = 0.03) or cloth masks (24.06 min, p = 0.04). No differences occurred in the slope of HR or SpO2 across conditions (p > 0.05). TcPCO2 decreased faster in control (B = −0.89) versus N95 (B = 0.14, p = 0.02) or cloth masks (B = −0.26, p = 0.03). RR increased faster in control (B = 8.32) versus cloth masks (B = 6.20, p = 0.04). RPE increased faster in the N95 (B = 1.91) and cloth masks (B = 1.79) versus control (B = 1.59, p < 0.001 and p = 0.05, respectively). Facial irritation/itching/pinching was higher in the N95 versus cloth masks, but sweat/moisture buildup was lower (p < 0.05 for all). Wearing cloth masks or N95s for source control may impact exercise performance, especially at higher intensities. Significant physiological differences were observed between cloth masks and N95s compared to control, while no physiological differences were found between cloth masks and N95s; however, comfort my differ.

Exercise intervention does not reduce the likelihood of VO2max underestimation in older adults with hypertension

ABSTRACT The present study aimed to investigate whether training status would influence the capacity of a verification phase (VER) to confirm maximal oxygen uptake (VO2max) of a previous graded exercise test (GXT) in individuals with hypertension. Twelve older adults with hypertension (8 women) were recruited. Using a within-subject design, participants performed a treadmill GXT to exhaustion followed by a multistage VER both before and after a 12-wkcombined exercise training programme. Individual VO2max, respiratory exchange ratio (RER), maximal heart rate (HRmax), and rating of perceived exertion (RPE) were measured during both GXT and VER tests. Absolute and relative VO2max values were higher in VER than in GXT at baseline, but only absolute VO2max differed between bouts post-intervention (all p < 0.05). Individual VO2max comparisons revealed that 75% of the participants (9/12) achieved a VO2max value that was ≥3% during VER both before (range: +4.9% to +21%) and after the intervention (range: +3.4% to +18.8%), whereas 91.7% (11/12) of the tests would have been validated as a maximal effort if the classic criteria were employed. A 12-wk combined training intervention could not improve the capacity of older adults with hypertension to achieve VO2max during a GXT, as assessed by VER.