Maximal Cycle Ergometer Exercise Research Articles

Revealing the unrevealed: echocardiography for non-ischemic scar tissue detection.

The detection of myocardial scar tissue profoundly influences athletes care and prognostic categorization. Athletes appear to be at risk of developing fatal arrhythmias when harboring a quiescent cardiac disorder. Early identification of disease in asymptomatic individuals through preparticipation screening is means to prevent these events. We presented a male marathon runner master athlete who came at our Department of Sports Medicine for a preparticipation screening. Baseline 12-lead standard electrocardiogram was normal. A maximal cycle ergometer exercise test revealed exercise-induced premature ventricular contractions (PVCs) with uncommon morphology. Echocardiography revealed an hyperechogenic zone at mid-basal posterior segments of the left ventricle. Twenty-four-hours ECG Holter monitoring, with training session, showed some isolated polymorphic PVCs even during training session. Cardiac magnetic resonance (CMR) confirmed the presence of a non-ischemic left ventricular scar (subepicardial) into the mid-basal segment of the posterior wall. Echocardiography is a first-line, economic, and accessible diagnostic test for athletes and it can be useful, when abnormalities are detected, to indicate further investigations, such as CMR. Although non-ischemic left ventricular scarring is difficult to detect on echocardiography, this event is sometimes possible and require further investigation when observed.

The Effects of Type of Exercise on Ventilatory Efficiency (VE/VCO2) in 11-16-Year-Old Healthy Individuals: A Randomized Clinical Trial

Background: The ventilatory equivalent for CO2 (VE/VCO2 ) is the simplest way to predict ventilatory efficiency. This study aimed to investigate the impact of treadmill and cycle ergometer exercise tests on ventilatory outcomes in healthy adolescents. Methods: In this clinical trial with cross-over design, 52 adolescents aged 11-16 years old (age: 13.8±0.17 years, height: 157.4±0.95 cm, weight: 51.73±1.24 kg, represented as mean±standard error), went through treadmill and cycle ergometer exercise tests with a 6-day wash-out during July-August 2019, Tehran, Iran. Through a RAMP (raise, activate, mobilise, and potentiate) protocol, participants were asked to perform the maximal treadmill or cycle ergometer exercise and continue the test until exhaustion. Gas exchange and heart rate (HR) were obtained breath by breath during the test. Time, HR, VE/VCO2, minute ventilation) VE), end-tidal carbon dioxide pressure (PetCO2), and dead space (VD) to tidal volume (VT) ratios (VD/VT) were transferred to the computer and recorded. All data were reported at two-time points: Anaerobic threshold (AT) V-slop method and peak. Independent t-test was then performed to compare the two types of exercises using SPSS 16, and P˂0.05 was considered significant. Results: The results showed a significant difference in two points regarding the type of exercise for Time and VE/VCO2, but for HR (P=0.004), VE (P=0.0001), PetCO2 (P=0.008), and VD/VT (P=0.004), a significant difference was only observed in AT point. Conclusion: Several physiological mechanisms that occurred during the development stage could affect individuals’ respiratory parameters; however, in general, the type of exercise test affected VE/VCO2.

Prognostic value of peak work rate indexed by left ventricular diameter

Left ventricular diameter (LVEDD) increases with systematic endurance training but also in various cardiac diseases. High exercise capacity associates with favorable outcomes. We hypothesized that peak work rate (Wpeak) indexed to LVEDD would carry prognostic information and aimed to evaluate the association between Wpeak/LVEDDrest and cardiovascular mortality. Wpeak/LVEDDrest (W/mm) was calculated in patients with an echocardiographic examination within 3 months of a maximal cycle ergometer exercise test. Low Wpeak/LVEDDrest was defined as a value below the sex- and age-specific 5th percentile among lower-risk subjects. The association with cardiovascular mortality was evaluated using Cox regression. In total, 3083 patients were included (8.0 [5.4–11.1] years of follow-up, 249 (8%) cardiovascular deaths). Wpeak/LVEDDrest (W/mm) was associated with cardiovascular mortality (adjusted hazard ratio (HR) 0.28 [0.22–0.36]), similar to Wpeak in % of predicted, with identical prognostic strength when adjusted for age and sex (C-statistics 0.87 for both). A combination of low Wpeak/LVEDDrest and low Wpeak was associated with a particularly poor prognosis (adjusted HR 6.4 [4.0–10.3]). Wpeak/LVEDDrest was associated with cardiovascular mortality but did not provide incremental prognostic value to Wpeak alone. The combination of a low Wpeak/LVEDDrest and low Wpeak was associated with a particularly poor prognosis.

Pattern of the heart rate performance curve in maximal graded treadmill running from 1100 healthy 18-65 Years old men and women: the 4HAIE study.

Introduction: The heart rate performance curve (HRPC) in maximal incremental cycle ergometer exercise demonstrated three different patterns such as downward, linear or inverse versions. The downward pattern was found to be the most common and therefore termed regular. These patterns were shown to differently influence exercise prescription, but no data are available for running. This study investigated the deflection of the HRPC in maximal graded treadmill tests (GXT) of the 4HAIE study. Methods: Additional to maximal values, the first and second ventilatory thresholds as well as the degree and the direction of the HRPC deflection (kHR) were determined from 1,100 individuals (489 women) GXTs. HRPC deflection was categorized as downward (kHR < -0.1), linear (-0.1 ≤ kHR ≤ 0.1) or inverse (kHR > 0.1) curves. Four (even split) age- and two (median split) performance-groups were used to investigate the effects of age and performance on the distribution of regular (= downward deflection) and non-regular (= linear or inverse course) HR curves for male and female subjects. Results: Men (age: 36.8 ± 11.9 years, BMI: 25.0 ± 3.3 kg m-2, VO2max: 46.4 ± 9.4 mL min-1. kg-1) and women (age: 36.2 ± 11.9 years, BMI: 23.3 ± 3.7 kg m-2, VO2max: 37.4 ± 7.8 mL min-1. kg-1) presented 556/449 (91/92%) downward deflecting, 10/8 (2/2%) linear and 45/32 (7/6%) inverse HRPC´s. Chi-squared analysis revealed a significantly higher number of non-regular HRPC´s in the low-performance group and with increasing age. Binary logistic regression revealed that the odds ratio (OR) to show a non-regular HRPC is significantly affected by maximum performance (OR = 0.840, 95% CI = 0.754-0.936, p = 0.002) and age (OR = 1.042, 95% CI = 1.020-1.064, p < 0.001) but not sex. Discussion: As in cycle ergometer exercise, three different patterns for the HRPC were identified from the maximal graded treadmill exercise with the highest frequency of regular downward deflecting curves. Older subjects and subjects with a lower performance level had a higher probability to show a non-regular linear or inverted curve which needs to be considered for exercise prescription.

Association between cardiorespiratory fitness and metabolic health in overweight and obese adults.

Cardiorespiratory fitness (CRF) has been inversely associated with insulin resistance and clustering of cardiometabolic risk factors among overweight and obese individuals. However, most previous studies have scaled CRF by body mass (BM) possibly inflating the association between CRF and cardiometabolic health. We investigated the associations of peak oxygen uptake (V̇O<inf>2peak</inf>) and peak power output (W<inf>peak</inf>) scaled either by BM-1, fat free mass (FFM-1), or by allometric methods with individual cardiometabolic risk factors and clustering of cardiometabolic risk factors in 55 overweight or obese adults with metabolic syndrome. V̇O<inf>2peak</inf> and W<inf>peak</inf> were assessed by a maximal cycle ergometer exercise test. FFM was measured by air displacement plethysmograph and glucose, insulin, HbA1c, triglycerides, and total, LDL, and HDL cholesterol from fasting blood samples. HOMA-IR and metabolic syndrome score (MetS) were computed. V̇O<inf>2peak</inf> and W<inf>peak</inf> scaled by BM-1 were inversely associated with insulin (β=-0.404 to -0.372, 95% CI: -0.704 to -0.048), HOMA-IR (β=-0.442 to -0.440, 95% CI: -0.762 to -0.117), and MetS (β=-0.474 to -0.463, 95% CI: -0.798 to -0.127). Other measures of CRF were not associated with cardiometabolic risk factors. Our results suggest that using BM-1 as a scaling factor confounds the associations between CRF and cardiometabolic risk in overweight/obese adults with the metabolic syndrome.

Heart Rate Performance Curve Is Dependent on Age, Sex, and Performance.

Introduction: The Heart Rate Performance Curve (HRPC) is neither linear nor uniform and related to ß1-adrenoceptor sensitivity. As aging and exercise influence ß1-adrenoceptors we suggested age, sex and performance effects on the HRPC. Aim of the study was to examine the effects of aging on the deflection of the HRPC in maximal incremental cycle ergometer exercise (CE) in a large cohort of healthy subjects.Methods: Heart rate (HR) data of 2,980 men (51 ± 15 years) and 1,944 women (52 ± 14 years) were classified into age groups (≤20 up to >80 years). We analyzed age and performance (Plow 25%-quartile and Phigh 75%-quartile of age predicted power) effects on HRmax and on the degree (k) and the type (regular downward deflection k > 0.1, linear −0.1 ≤ k ≤ 0.1 and atypical upward deflection k < −0.1) of the HRPC.Results: k-values decreased significantly with age in men and women and were significantly higher in women. Atypical HRPC's increased by a linear trend from ≤20 to 70 years (m) respectively 80 years (w) from 10 to 43% (m) and 9 to 30% (w). HRmax of all age groups was lower in Plow and overall number of atypical HRPC's was 21% (m) and 16% (w) higher compared to Phigh.Conclusion: Aging increased the number of atypical HRPC's with upward deflection in CE tests, which influences exercise intensity prescription especially when using fixed percentages of HRmax. Changes in HRPC's were affected by sex and performance, where women generally and subjects with higher performance presented less atypical HRPC's even at older age.

Cardiorespiratory Fitness, Physical Activity, and Insulin Resistance in Children.

Few studies have investigated the independent and joint associations of cardiorespiratory fitness (CRF) and body fat percentage (BF%) with insulin resistance in children. We investigated the independent and combined associations of CRF and BF% with fasting glycemia and insulin resistance and their interactions with physical activity (PA) and sedentary time among 452 children age 6 to 8 yr. We assessed CRF with a maximal cycle ergometer exercise test and used allometrically scaled maximal power output (Wmax) for lean body mass (LM) and body mass (BM) as measures of CRF. The BF% and LM were measured by dual-energy X-ray absorptiometry, fasting glycemia by fasting plasma glucose, and insulin resistance by fasting serum insulin and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR). The PA energy expenditure, moderate-to-vigorous PA (MVPA), and sedentary time were assessed by combined movement and heart rate sensor. Wmax/LM was not associated with glucose (β = 0.065, 95% confidence interval [CI] = -0.031 to 0.161), insulin (β = -0.079, 95% CI = -0.172 to 0.015), or HOMA-IR (β = -0.065, 95% CI = -0.161 to 0.030). Wmax/BM was inversely associated with insulin (β = -0.289, 95% CI = -0.377 to -0.200) and HOMA-IR (β = -0.269, 95% CI = -0.359 to -0.180). The BF% was directly associated with insulin (β = 0.409, 95% CI = 0.325 to 0.494) and HOMA-IR (β = 0.390, 95% CI = 0.304 to 0.475). Higher Wmax/BM, but not Wmax/LM, was associated with lower insulin and HOMA-IR in children with higher BF%. Children with higher BF% and who had lower levels of MVPA or higher levels of sedentary time had the highest insulin and HOMA-IR. Children with higher BF% together with less MVPA or higher levels of sedentary time had the highest insulin and HOMA-IR. Cardiorespiratory fitness appropriately controlled for body size and composition using LM was not related to insulin resistance among children.

Associations of physical activity, sedentary time, and cardiorespiratory fitness with heart rate variability in 6- to 9-year-old children: the PANIC study

PurposeTo study the associations of physical activity (PA), sedentary time (ST), and cardiorespiratory fitness (CRF) with heart rate variability (HRV) in children.MethodsThe participants were a population sample of 377 children aged 6–9 years (49% boys). ST, light PA (LPA), moderate PA (MPA), vigorous PA (VPA), and moderate-to-vigorous PA (MVPA), and PA energy expenditure (PAEE) were assessed using a combined heart rate and movement sensor, maximal power output per kilograms of lean body mass as a measure of CRF by maximal cycle ergometer exercise test, and HRV variables (SDNN, RMSSD, LF, and HF) using 5 min resting electrocardiography. Data were analysed by linear regression adjusted for years from peak height velocity.ResultsIn boys, ST was inversely associated (β = − 0.185 to − 0.146, p ≤ 0.049) and MVPA, VPA, PAEE, and CRF were directly associated (β = 0.147 to 0.320, p ≤ 0.048) with HRV variables. CRF was directly associated with all HRV variables and PAEE was directly associated with RMSSD after mutual adjustment for ST, PAEE, and CRF (β = 0.169 to 0.270, p ≤ 0.046). In girls, ST was inversely associated (β = − 0.382 to − 0.294, p < 0.001) and LPA, MPA, VPA, MVPA, and PAEE were directly associated with HRV variables (β = 0.144 to 0.348, p ≤ 0.049). After mutual adjustment for ST, PAEE, and CRF, only the inverse associations of ST with HRV variables remained statistically significant.ConclusionsHigher ST and lower PA and CRF were associated with poorer cardiac autonomic nervous system function in children. Lower CRF in boys and higher ST in girls were the strongest correlates of poorer cardiac autonomic function.

Exercise stress test in apparently healthy individuals - where to place the finish line? The Ferrari corporate wellness programme experience.

The aim of our study was to assess the clinical significance of the exercise stress testing endpoints, namely 85% of maximal theoretical heart rate (MTHR), metabolic equivalent of task, and rating of perceived exertion (RPE), and their relation to electrocardiographic (ECG) changes in a healthy adult population. A cross-sectional study was conducted on 408 males and 52 females (mean age 39.4 ± 8.6 years) who performed the maximal cycle ergometer exercise stress test until volitional exhaustion, reporting the RPE score at 85% of MTHR and at peak exercise. Metabolic equivalents of task were indirectly calculated from the maximum workload and compared with the predicted values. Sitting torso-lead ECG and blood pressure were recorded at rest, during exercise and during recovery. Of 460 participants, 73% exceeded 85% of MTHR. The RPE score represented the overall most significant endpoint of exercise stress testing, with the median value of 17 at peak exercise. ECG events were detected in 23/124 (18.5%) who reached ≤ 85% of MTHR and in 61/336 (18.2%) who achieved >85% of MTHR ( p = 0.92). In the latter group, 54% of ECG changes occurred at < 85% of MTHR and 46% at > 85% of MTHR ( p = 0.51). If the exercise stress testing had been interrupted at ≤ 85% of MTHR, almost half of the ECG events would have remained undetected and 35% of the cardiovascular abnormalities observed at the diagnostic follow-up would have remained undiagnosed. Terminating exercise stress testing before volitional exhaustion and an RPE score of 17 limits the test accuracy and reduces the possibility to detect cardiovascular abnormalities in apparently healthy adult populations.

Peak oxygen uptake cut-points to identify children at increased cardiometabolic risk - The PANIC Study.

We aimed to develop cut-points for directly measured peak oxygen uptake ( ) to identify boys and girls at increased cardiometabolic risk using different scaling methods to control for body size and composition. Altogether 352 children (186 boys, 166 girls) aged 9-11years were included in the analyses. We measured V̇O2peak directly during a maximal cycle ergometer exercise test and lean body mass (LM) by bioelectrical impedance. We computed a sex- and age-specific cardiometabolic risk score (CRS) by summing important cardiometabolic risk factors and defined increased cardiometabolic risk as >1 standard deviation above the mean of CRS. Receiver operating characteristics curves were used to detect V̇O2peak cut-points for increased cardiometabolic risk. Boys with V̇O2peak <45.8mLkgbody mass (BM)-1 min-1 (95% confidence interval [CI] = 45.1 to 54.6, area under the curve [AUC] = 0.86, P<0.001) and <63.2mLkgLM-1 min-1 (95% CI =52.4 to 67.5, AUC = 0.65, P=0.006) had an increased CRS. Girls with V̇O2peak <44.1mLkgBM-1 min-1 (95% CI = 44.0 to 58.6, AUC = 0.67, P=0.013) had an increased CRS. V̇O2peak scaled by BM-0.49 and LM-0.77 derived from log-linear allometric modeling poorly predicted increased cardiometabolic risk in boys and girls. In conclusion, directly measured <45.8mLkgBM-1 min-1 among boys and <44.1mLkgBM-1 min-1 among girls were cut-points to identify those at increased cardiometabolic risk. Appropriately controlling for body size and composition reduced the ability of cardiorespiratory fitness to identify children at increased cardiometabolic risk.

Effects of different endurance exercise modalities on retinal vessel diameters in unipolar depression

BackgroundPsychiatric disorders are associated with a high prevalence of cardiovascular disease. Regular exercise is known to reduce depressive symptoms and improve vascular function, in turn lowering cardiovascular risk. We aimed to investigate the effects of different exercise modalities on retinal vessel diameters as a microvascular biomarker and depression severity index in patients suffering from unipolar depression. Methods23 patients (female: 19, male: 4, age: 36.7, Beck-Depression-Inventory-II (BDI-II) score: 30.7) were enrolled in this two-armed randomized controlled trial. Static vessel analysis was performed to obtain central retinal arteriolar (CRAE) and venular (CRVE) diameter equivalents and the arterio-venous diameter ratio (AVR). Maximal bicycle ergometer exercise testing yielded maximal fitness parameters. Patients were assigned to either high intensity low volume (HILV) or moderate continuous aerobic training (MCT). Both intervention groups trained three times a week during a 4-week intervention period. ResultsModerate interaction effects were found for AVR (ɳp2 = 0.12) whereby HILV showed a larger increase in AVR (HILV: pre: 0.89 (0.04), post: 0.91 (0.04), SMD = −0.50) compared to MCT (MCT: pre: 0.85 (0.06), post: 0.86 (0.05), SMD = −0.18). Parallel group trials revealed a 67% possibly beneficial effect of HILV over MCT. Moderate interaction effects on depression severity reduction (ɳp2 = 0.06) were found, whereby the effect size was slightly larger in MCT. ConclusionBoth exercise interventions improved AVR as well as BDI-II. HILV may be more effective in improving cerebrovascular health. The exercise-induced effects on retinal vessel diameter changes were relatively small and the clinical relevance remains to be investigated in larger and longer-term exercise trials.

Sprint interval training (SIT) substantially reduces depressive symptoms in major depressive disorder (MDD): A randomized controlled trial

Continuous aerobic exercise training (CAT) is considered a complementary treatment option in patients with major depressive disorder (MDD). Intermittent exercise training protocols, such as sprint interval training (SIT) have gained increasing popularity, but no studies on depressive symptoms following SIT in patients with MDD are available. Fifty-nine in-patients with MDD were randomly assigned to a SIT or CAT group. Medication was counterbalanced in both intervention arms. Both intervention groups received 3 weekly training sessions for 4-weeks (12 sessions in total). SIT comprised 25 bouts of 30 seconds at 80% of maximal power, whereas CAT consisted of 20 minutes of physical activity at 60% of maximal power. The training protocols were isocalorically designed. Maximal bicycle ergometer exercise testing yielded maximal and submaximal physical fitness parameters. The Beck-Depression-Inventory-II (BDI-II) was filled out by the patients before and after the intervention period. BDI-II scores substantially decreased in both groups with an effect size pointing towards a large effect (p < 0.001, ηp² = 0.70) while submaximal (0.07 < d < 0.89) and maximal (0.05 < d < 0.85) fitness variables improved in both groups. Short-term SIT leads to similar results as CAT in patients with MDD and can be regarded as a time-efficient and promising exercise-based treatment strategy.

Effects of Endurance Exercise Modalities on Arterial Stiffness in Patients Suffering from Unipolar Depression: A Randomized Controlled Trial.

Psychiatric disorders are associated with a higher prevalence of cardiovascular disease and mortality. Regular exercise has been shown to reduce depressive symptoms and improve arterial stiffness as a biomarker of cardiovascular risk. We aimed to investigate the effects of different exercise modalities on depression severity index and arterial stiffness in patients suffering from unipolar depression. 34 patients suffering from unipolar depression [female: 25, male: 9, age: 37.8, Beck-Depression-Inventory-II (BDI-II) score: 31.0] were enrolled in this two-armed randomized controlled trial. Central hemodynamics, augmentation index at heart rate 75/min (AIx@75) and aortic pulse wave velocity (PWV) were obtained by an oscillometric monitoring device. Maximal bicycle ergometer exercise testing yielded maximal fitness parameters. Patients were assigned to either high-intensity low volume (HILV) or moderate continuous aerobic training (MCT). Both intervention groups trained three times a week during a 4-week intervention period. BDI-II were filled out by the patients before and after the intervention period. We found moderate interaction effects on depression severity reduction [Formula: see text]. HILV showed a 85% beneficial effect in lowering BDI-II scores compared to MCT (HILV: pre: 28.8 (9.5), post: 15.5 (8.5), SMD = 1.48), MCT: (pre: 33.8 (8.5), post: 22.6 (7.5), SMD = 1.40). Reduction of AIx@75 was more pronounced after MCT (SMD = 0.61) compared to HILV (SMD = 0.08), showing 37% possibly beneficial effects of MCT over HILV. PWV remained unchanged in both training groups. Both training regimes showed large effects on the reduction of depressive symptoms. While HILV was more effective in lowering depression severity, MCT was more effective in additionally lowering peripheral arterial stiffness. Exercise should be considered an important strategy for preventive as well as rehabilitative treatment in depression.

Vascular Dynamics and Peripheral Oxygen Uptake in Obese Individuals during Progressive Physical Exercise

Background: Obese men show higher O₂ consumption than lean men during physical exercise, with a trend toward higher peripheral O₂ extraction; this is probably due to their larger muscle mass. Objectives: The aim of this study was to examine this phenomenon by measuring 2 vasoactive substances, endothelin-1 (ET-1) and nitric oxide (NO), during a progressive submaximal exercise. Methods: Seventeen obese (body mass index [BMI] 38.6) and 15 lean (BMI 22.5) men performed a maximal progressive cycle ergometer exercise to determine peak power output (PPO) and peak O₂ consumption (V∙O₂_peak); thereafter, they performed a submaximal cycle ergometer incremental test (every 6 min) at the same percentage of V∙O₂_peak until they reached 57.5% PPO. Blood samples were collected at rest and at the end of every step to measure ET-1 and NO concentrations. Results: At rest, the ET-1 and NO concentrations in obese men and lean controls were the same. However, during exercise, the ET-1 concentration at each step was significantly lower (p < 0.05) in the obese group. There was no significant difference in NO concentration between the 2 groups, although the increase at the beginning of the exercise session was faster in obese individuals. During submaximal exercise, end-tidal O₂ pressure (PETO₂) was lower in the obese group, with a significant difference in the PETO₂/fat-free mass ratio at each step. Conclusions: ET-1 and NO levels during physical exercise are different in obese versus lean men. This may support the notion that increased O₂ consumption in obesity is due to different behaviors of the cardiorespiratory and circulatory systems.

Somatotype variables related to strength and power output in male basketball players.

The purpose of this study was to investigate the relationship between somatotype, muscular strength, power output measured in maximal cycle ergometer exercise bouts, and maximal power output and height of rise of the body mass centre (jump height) measured in akimbo counter movement jump (ACMJ), counter movement jump (CMJ) and spike jump (SPJ), in male basketball players. Thirteen male basketball players (second division, age 19.4 ± 0.8 years, body height 192.9 ± 5.6 cm, body mass 88.8 ± 8.6 kg, training experience 9.3 ± 0.8 years) participated in the study. Somatotype was determined using the Heath-Carter method. Maximal joint torques were measured under static conditions. Power output was measured in 2 maximal cycle ergometer exercise bouts, 10 seconds each, with increasing external loads equal to 7.5 and 10.0% of the body weight (BW). All jump trials (ACMJ, CMJ and SPJ) were performed on a force plate. The mean somatotype of basketball players amounted to: 2.8-4.2-3.2. The sum of the joint torques for left and right lower extremities (0.613), trunk (0.631) and all six measured muscle groups (0.647) were significantly correlated (p < 0.05) with the mesomorphic component. Endomorphic, mesomorphic and ectomorphic components were correlated insignificantly with values of maximal power and height of jump during ACMJ, CMJ and SPJ trials. The power output measured in maximal cycle ergometer exercise bouts with increasing external loads was significantly correlated (p < 0.05) with mesomorphy and ectomorphy. It can be assumed that basketball players' anthropometric characteristics can influence their level of performance but it is not a decisive factor.

Determinants of Cardiorespiratory Fitness in a Population Sample of Girls and Boys Aged 6 to 8 Years.

There are few studies on determinants of cardiorespiratory fitness (CRF) among girls and boys separately in population samples of children. We therefore investigated the determinants of CRF, assessed by maximal workload per height using allometric scaling, in a population sample of 162 girls and 177 boys aged 6 to 8 years. We used automated bootstrap feature selection and linear regression models. The strongest determinants of CRF among girls were maximal heart rate (HR; standardized regression coefficient [β] = 0.31, P < .001), unsupervised physical activity (β = 0.29, P < .001), lean body mass (β = 0.23, P = .001), and errors in static balance test (β = -0.16, P = .02), accounting altogether for 25.7% of variation in CRF. In boys, unsupervised physical activity (β = 0.24, P < .001), resting HR (β = -0.25, P < .001), hand grip strength (β = 0.21, P = .001), errors in static balance test (β = -0.16, P = .01), organized football (β = 0.16, P = .01), and unsupervised trampoline jumping (β = 0.14, P = .04) were the strongest determinants of CRF, accounting altogether for 29.7% of variation in CRF. These findings suggest that unsupervised physical activity is sufficient in improving CRF in both sexes. Furthermore, larger muscle mass and better balance are associated with higher CRF that has to be taken into account when assessing CRF using maximal cycle ergometer exercise test among children.

Power-velocity characteristics and jumping abilities in male combat athletes

PurposeThe aim of the study was to examine differences in power-velocity characteristics, and the maximal power and height of rise of the body’s centre of mass, measured in the counter-movement jump (CMJ) and the spike jump (SPJ), between judoists, boxers and taekwondo athletesMethodsThe study involved 7 judoists, 6 boxers, and 6 taekwondo athletes. The maximal power and height of jump were measured at CMJ and SPJ jumps. Force-velocity and power-velocity relations were determined on the basis of 5 maximal cycle ergometer exercise bouts at increasing external loads of 2.5, 5.0, 7.5, 10.0, and 12.5% of body weight (BW)ResultsThe absolute and relative power and velocity recorded for an external force-velocity relationship were similar in the groups. A significant difference was only observed between taekwondo athletes and judoists for absolute power at the external load of 2.5% BW (&lt;i&gt;p&lt;/i&gt; &lt; 0.05). The judoists had significantly smaller relative maximal power in SPJ (&lt;i&gt;p&lt;/i&gt; &lt; 0.05) and height of rise of the body mass centre in CMJ (&lt;i&gt;p&lt;/i&gt; &lt; 0.05) than taekwondo athletes. The relative maximal power in CMJ and height of rise of the body mass centre in SPJ was similar in the groups.ConclusionsIn martial arts, training and competition should affect physical characteristics, including jumping and power. The power and velocity recorded for an external forcevelocity relationship were similar in the groups. Judoists and boxers did not differ in terms of power or height of the jumps. Taekwondo athletes developed the biggest power and height of the jumps. This is consistent with the discipline characteristics.

Associations of cardiorespiratory fitness, physical activity, and adiposity with arterial stiffness in children.

Associations of cardiorespiratory fitness (CRF), physical activity (PA), sedentary behavior, and body fat percentage (BF%) with arterial stiffness and dilation capacity were investigated in 160 prepubertal children (83 girls) 6-8 years of age. We assessed CRF (watts/lean mass) by maximal cycle ergometer exercise test, total PA, structured exercise, unstructured PA, commuting to and from school, recess PA and total and screen-based sedentary behavior by questionnaire, BF% using dual-energy X-ray absorptiometry, and arterial stiffness and dilation capacity using pulse contour analysis. Data were adjusted for sex and age. Poorer CRF (standardized regression coefficient β = -0.297, P < 0.001), lower unstructured PA (β = -0.162, P = 0.042), and higher BF% (β = 0.176, P = 0.044) were related to higher arterial stiffness. When CRF, unstructured PA, and BF% were in the same model, only CRF was associated with arterial stiffness (β = -0.246, P = 0.006). Poorer CRF was also related to lower arterial dilation capacity (β = 0.316, P < 0.001). Children with low CRF (< median) and high BF% (≥ median; P = 0.002), low CRF and low unstructured PA (< median; P = 0.006) or children with low unstructured PA and high BF% (P = 0.005) had higher arterial stiffness than children in the opposite halves of these variables. Poor CRF was independently associated with increased arterial stiffness and impaired arterial dilation capacity among children.

Mechanisms underlying enhancements in muscle force and power output during maximal cycle ergometer exercise induced by chronic β2-adrenergic stimulation in men

The study was a randomized placebo-controlled trial investigating mechanisms by which chronic β2-adrenergic stimulation enhances muscle force and power output during maximal cycle ergometer exercise in young men. Eighteen trained men were assigned to an experimental group [oral terbutaline 5 mg/30 kg body weight (bw) twice daily (TER); n = 9] or a control group [placebo (PLA); n = 9] for a 4-wk intervention. No changes were observed with the intervention in PLA. Isometric muscle force of the quadriceps increased (P ≤ 0.01) by 97 ± 29 N (means ± SE) with the intervention in TER compared with PLA. Peak and mean power output during 30 s of maximal cycling increased (P ≤ 0.01) by 32 ± 8 and 25 ± 9 W, respectively, with the intervention in TER compared with PLA. Maximal oxygen consumption (V̇o2max) and time to fatigue during incremental cycling did not change with the intervention. Lean body mass increased by 1.95 ± 0.8 kg (P ≤ 0.05) with the intervention in TER compared with PLA. Change in single fiber cross-sectional area of myosin heavy chain (MHC) I (1,205 ± 558 μm(2); P ≤ 0.01) and MHC II fibers (1,277 ± 595 μm(2); P ≤ 0.05) of the vastus lateralis muscle was higher for TER than PLA with the intervention, whereas no changes were observed in MHC isoform distribution. Expression of muscle proteins involved in growth, ion handling, lactate production, and clearance increased (P ≤ 0.05) with the intervention in TER compared with PLA, with no change in oxidative enzymes. Our observations suggest that muscle hypertrophy is the primary mechanism underlying enhancements in muscle force and peak power during maximal cycling induced by chronic β2-adrenergic stimulation in humans.

Metabolic Syndrome, Brachial Artery Diameter and Cardiorespiratory Fitness - The DR’s EXTRA Study

The metabolic syndrome (MetS) is characterized by a systemic arterial remodeling which can be proved by a large brachial artery diameter (BAD). The arterial enlargement may result, however, also from long-term endurance-type physical activity (PA). PURPOSE: To study whether the association of a large BAD with prevalence of MetS can be further defined by allowing for the cardiorespiratory fitness as a proxy variable for long-term endurance-type PA. METHODS: The subjects were a population-based sample of 593 men and 583 women aged 57-78 years who participated in the DR’s EXTRA Study. Metabolic syndrome was determined by the NCEP criteria. The end-diastolic BAD was assessed by ultrasound and cardiorespiratory fitness as peak oxygen uptake (VO2peak) achieved in a maximal cycle ergometer exercise test. Age-adjusted linear regression analysis was used to compare the means of BAD in those with or without MetS. For the main analyses, sex-spesific tertiles of BAD and VO2peak were pooled in age-adjusted logistic regression analyses and the association was explored after the highest tertile of BAD (>4.25 mm in men, >3.36 mm in women) was further categorized according to tertiles of VO2peak (low ≤23.3 and high >28.9 ml/kg/min in men; low ≤18.4 and high >22.8 ml/kg/min in women). RESULTS: Mean BAD was higher in 323 (27%) subjects with MetS compared to those without MetS (3.80 vs. 3.63 mm, p<0.001 for difference between groups). Subjects (n=141) with a large BAD and a low VO2peak had an increased risk of having MetS (OR 5.1 [95% confidence interval, CI, 3.5-7.6], p<0.001) compared to subjects with narrower BAD (the two lowest tertiles). Additionally, 123 subjects with a large BAD but a high VO2peak had a decreased risk of having MetS (OR 0.4 [95% CI 0.2-0.8], p=0.004) compared to subjects with narrower BAD. The results were similar when assessed separately in men and women. CONCLUSION: The group with a large BAD includes subjects with unfavourable vascular risk factor profile judged by an increased risk of having MetS, but also subjects with a decreased risk of having MetS. These groups can be identified based on cardiorespiratory fitness. A large BAD should not be interpreted unambiguously as an unfavourable finding from viewpoint of vascular health without considering whether it may result from long-term endurance-type PA as well.