Relative Peak Oxygen Uptake Research Articles

Aerobic capacity in swimming, cycling and arm cranking in swimmers aged 11–13 years

BackgroundThis study aimed to compare the aerobic capacity in swimming, cycling and arm cranking in swimmers aged 11–13 years.MethodsEleven swimmers (mean age, 12.1 ± 1.0 years) performed three incremental exercise tests. One of the tests was performed under specific conditions (front crawl swimming), and the other two were under non–specific conditions (cycling and arm cranking). Data on the pulmonary gas exchange were recorded using the portable analyser MetaMax 3B (Cortex, Leipzig, Germany). One-way analysis of variance for repeated measures was employed to test the null hypothesis and determine statistically significant differences between the indicators obtained under specific and non–specific testing conditions. Pearson’s correlation coefficient was calculated to assess the relationships between the indicators of the pulmonary gas exchange.ResultsThe relative peak oxygen uptake (V̇O2peak) value during swimming was 49.3 ± 6.2 mL/kg/min, which was higher than that during arm cranking (39.6 ± 7.3 mL/kg/min; P < 0.01) but lower than that during cycling (54.3 ± 7.8 mL/kg/min; P < 0.01). The peak minute ventilation (V̇Epeak) value during swimming (84.9 ± 12.6 L/min) was higher than that during arm cranking (69.4 ± 18.2 L/min; P < 0.01) but lower than that during cycling (98.4 ± 15.4 L/min; P < 0.01). Strong positive correlations were observed in the absolute and relative V̇O2peak values between swimming and cycling (r = 0.857, P < 0.01; r = 0.657, P < 0.05) and between swimming and arm cranking (r = 0.899, P < 0.01; r = 0.863, P < 0.05). A strong positive correlation was also observed in V̇Epeak values between swimming and arm cranking (r = 0.626, P < 0.05).ConclusionSwimmers aged 11–13 years showed V̇O2peak and V̇Epeak values during the specific swimming test greater than those during arm cranking but lower than those during cycling. However, aerobic capacity parameters measured during specific swimming conditions correlated with those measured during non–specific arm cranking and cycling conditions.

Altered Expiratory Flow Dynamics at Peak Exercise in Adult Men With Well-Controlled Type 1 Diabetes

Type 1 diabetes may, in time, cause lung dysfunction including airflow limitation. We hypothesized that ventilatory flow morphology during a cardiopulmonary exercise test (CPET) would be altered in adult men with well-controlled type 1 diabetes. Thirteen men with type 1 diabetes [glycated hemoglobin A1c 59 (9) mmol/mol or 7.5 (0.8)%, duration of diabetes 12 (9) years, and age 33.9 (6.6) years] without diagnosed diabetes-related complications and 13 healthy male controls [age 37.2 (8.6) years] underwent CPET on a cycle ergometer (40 W increments every 3 min until volitional fatigue). We used a principal component analysis based method to quantify ventilatory flow dynamics throughout the CPET protocol. Last minute of each increment, peak exercise, and recovery were examined using linear mixed models, which accounted for relative peak oxygen uptake and minute ventilation. The type 1 diabetes participants had lower expiratory peak flow (P = 0.008) and attenuated slope from expiration onset to expiratory peak flow (P = 0.012) at peak exercise when compared with the healthy controls. Instead, during submaximal exercise and recovery, the type 1 diabetes participants possessed similar ventilatory flow dynamics to that of the healthy controls. In conclusion, men with relatively well-controlled type 1 diabetes and without clinical evidence of diabetes-related complications exhibited attenuated expiratory flow at peak exercise independently of peak oxygen uptake and minute ventilation. This study demonstrates that acute exercise reveals alterations in ventilatory function in men with type 1 diabetes but not until peak exercise.

Metabolic And Ventilatory Responses To Exercise In Young Adults Following Sars-cov-2 Infection

BACKGROUND: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) targets organ angiotensin-converting enzyme 2 receptors and infection can lead to pulmonary and cardiovascular abnormalities. PURPOSE: To examine whether metabolic and cardiorespiratory responses during exercise were different in young adults who previously tested positive for SARS-CoV-2 compared with control participants. METHODS: A cross-sectional analysis (n = 26) was performed between young adults that tested positive for SARS-CoV-2 in the three-to-four weeks prior to data collection (CoV+: n = 13) and healthy control participants (CON: n = 13). Participants were matched according to sex, age, and BMI (CoV+: 7F, 21 ± 1 yr, 24.3 ± 3.0 kg·m-2; CON: 7F; 21 ± 2, 23.3 ± 3.5 kg·m-2; p > 0.05). Participants completed an incremental peak aerobic capacity test on a cycle ergometer. Metabolic and cardiorespiratory measurements were collected every minute using a metabolic cart. Data were compared at rest and during cycling at 60 W, 120 W, and at peak exercise. Values are expressed as mean ± SD. RESULTS: No significant differences were observed between groups for relative or absolute peak oxygen uptake (V̇O2peak) (CoV+: 35.6 ± 5.8 mL·kg-1·min-1, 2.64 ± 0.68 L·min-1; CON: 33.3 ± 6.5 mL·kg-1 ·min-1, 2.37 ± 0.68 L·min-1, respectively; p > 0.05). Heart rate expressed as absolute or as a percentage of age-predicted maximum values was not different between CoV+ and CON (p > 0.05). Minute ventilation (V̇E), tidal volume, and breathing frequency were similar between groups at each exercise intensity (p > 0.05). The ratio of V̇E to the volume of carbon dioxide produced (V̇E/V̇CO2) was not significantly different at any stage of exercise between groups (p > 0.05). Additionally, ratings of perceived exertion were similar at submaximal intensities (CoV+: 8.2 ± 1.8 60 W, 11.2 ± 2.1 120 W; CON: 8.2 ± 2.4 60 W, 11.2 ± 3.8 120 W; p > 0.05) and at V̇O2peak (CoV+: 16.4 ± 2.6; CON: 17.1 ± 2.0, p > 0.05). CONCLUSIONS: Metabolic and cardiorespiratory responses during incremental exercise test were not different between young, healthy control participants and individuals who tested positive for SARS-CoV-2 three-to-four weeks prior. These data suggest that exercise after 3-4 weeks following SARS-CoV-2 infection does not alter physiological or perceptual responses in young adults.

The Effectiveness of a 30-Week Concurrent Strength and Endurance Training Program in Preparation for an Ultra-Endurance Handcycling Challenge: A Case Study.

The aim of the following case study was to evaluate the effectiveness of a 30-week concurrent strength and endurance training program designed to prepare a trained H4 male handcyclist (aged 28y, bilateral, above knee amputee, and body mass 65.6kg) for a 1407-km ultra-endurance handcycling challenge. This observational case study tracked selected physiological measures, training intensity distribution, and total training load over the course of a 30-week concurrent training protocol. Furthermore, the athlete's performance profile during the ultra-endurance challenge was monitored with power output, cadence, speed, and heart rate recorded throughout. Findings revealed considerable improvements in power output at a fixed blood lactate concentration of 4mmol·L-1 (+25.7%), peak aerobic power output (+18.9%), power-to-mass ratio (+18.3%), relative peak oxygen uptake (+13.9%), gross mechanical efficiency (+4.6%), bench press 1-repetition maximum (+4.3%), and prone bench pull 1-repetition maximum (+14.9%). The athlete completed the 1407-km route in a new handcycling world record time of 89:55hours. Average speed was 18.7 (2.1)km·h-1; cadence averaged 70.0 (2.6)rpm, while average power output was 67 (12)W. In terms of internal load, the athlete's average heart rate was 111 (11)beats per minute. These findings demonstrate how a long-term concurrent strength and endurance training program can be used to optimize handcycling performance capabilities in preparation for an ultra-endurance cycling event. Knowledge emerging from this case study provides valuable information that can guide best practices with respect to handcycling training for ultra-endurance events.

Association of Exercise Intolerance With Emotional Distress, Attainment of Social Roles, and Health-Related Quality of Life Among Adult Survivors of Childhood Cancer

Exercise intolerance is associated with increased risk for morbidity and mortality in childhood cancer survivors. However, an association between exercise intolerance and psychosocial outcomes has not been fully explored. To examine the associations between exercise intolerance and emotional distress, attainment of social roles, and health-related quality of life in childhood cancer survivors. A cross-sectional study including 1041 adult survivors of childhood cancer and 286 community controls in the St Jude Lifetime Cohort was conducted at St Jude Children's Research Hospital. The study was performed from April 1, 2012, to March 15, 2020. Exercise intolerance was defined as relative peak oxygen uptake less than 85% of age- and sex-estimated levels from maximal cardiopulmonary exercise testing. Emotional distress was measured with the 18-item Brief Symptom Inventory-18, which includes overall Global Severity Index and depression, anxiety, and somatization subscales. Participants with T scores greater than or equal to 63 were classified as having elevated levels of distress. Social attainment was evaluated using patient-reported educational, employment, and marital status. Health-related quality of life was examined with the Medical Outcomes Survey Short Form-36. Participants with T scores less than or equal to 40 were classified as reporting poor health-related quality of life. Of the 1041 participants, 528 were women (50.7%). The prevalence of exercise intolerance among survivors (mean [SD] age, 35.5 [9.2] years) was higher than that among controls (age, 34.5 [10.0] years) (survivors: 634 [60.9%] vs controls: 75 [26.2%], P < .001). After adjusting for age at diagnosis and cardiopulmonary exercise testing, sex, race/ethnicity, smoking, physical activity, and exercise intolerance were associated with an increased risk for anxiety (prevalence rate ratio [PRR], 1.95; 95% CI, 1.20-3.16), somatization (PRR, 1.86; 95% CI, 1.23-2.80), and unemployment (PRR, 1.76; 95% CI, 1.23-2.52); an inverse association was noted with having a college degree (PRR, 0.67; 95% CI, 0.50-0.88). Exercise intolerance was associated with an increased the risk for scoring less than or equal to 40 on the physical component summary of the Medical Outcomes Survey Short Form-36 (PRR, 3.69; 95% CI, 2.34-5.84). These associations persisted when either cancer treatment exposures or chronic health conditions were added to the model. The findings of this study suggest that exercise intolerance is independently associated with emotional distress, attainment of social roles, and health-related quality of life of long-term survivors of childhood cancer. The results also suggest that improving physiologic capacity may benefit general health and wellness, as well as emotional health, ability to participate in social roles, and health-related quality of life.

Effects of 1‐year Aerobic Exercise Training on Cerebral Blood Flow and Arterial Siffness in Amnestic Mild Cognitive Impairment

Aerobic exercise training (AET) may improve cerebralperfusion and reduce the risk of dementia. Changes in central arterialstiffness and pulsatile cerebral blood flow (CBF) associated with exercise training may be one of the underlying pathophysiological mechanism. The purpose of this study was to investigate: (1) The effects of AET on central arterialstiffness and CBF, and (2) whether pulsatile CBF mediates the association between changes in arterial stiffness and cerebral perfusion in amnestic mildcognitive impairment (aMCI), a prodromal stage of Alzheimer disease. Seventy aMCI patients were randomized to 12 months of moderate‐intensity AET (n=31) or stretching program (n=39). CBF and carotid β‐stiffness index were assessed by ultrasonography and applanation tonometry. Cerebral perfusion was calculated by normalizing total CBF to brain tissue mass measured by magnetic resonance imaging. Pulsatile CBF was measured from the middle cerebralartery using transcranial Doppler. Cardiorespiratory fitness was assessed by peak oxygen uptake (VO2peak). VO2peak and cerebralperfusion increased and carotid β‐stiffness index decreased in the AET group, while remained unchanged in the stretching group. The change in VO2peak was significantly associated with the change in cerebral perfusion, carotidβ‐stiffness index, and pulsatile CBF (Fig. 1). The decrease in carotidβ‐stiffness was associated with increased in cerebral perfusion (Fig. 2). Mediation analysis showed that changes in pulsatile CBF mediates the association between carotidβ‐stiffness index and cerebral perfusion (Fig. 2). These results suggest that AET decreases arterial stiffness and increases cerebral perfusion, which is mediated by pulsatile CBF in aMCI patients.Support or Funding InformationThis work was funded by the National Institutes of Health ((R01AG033106, R01HL102457, P30AG012300)Associations between the change (Δ) in relative peak oxygen uptake (VO2) and the change in cerebral perfusion, carotid β‐stiffness index and pulsatile cerebral blood flow (CBF).Figure 1Mediation analysis diagram of the effect of the change (Δ) in carotid β‐stiffness index on the change in cerebral perfusion through the change in pulsatile cerebral blood flow (CBF).Figure 2

Cardiorespiratory Fitness Normative Values in Latin-American Adolescents: Role of Fatness Parameters.

The aim of this study was to provide percentile values for a cardiorespiratory fitness (CRF) field test for Latin-American adolescents (34,461 girls and 38,044 boys) aged 13 to 15 years. The role of fatness parameters on the CRF level across age groups was also examined, with a focus on non-obese (healthy) and obese groups. CRF was assessed using the 20-meter shuttle run test protocol. Anthropometric parameters were measured using body mass index z-score (body mass index (BMI) z-score), BMI, waist circumference (WC), and waist-to-height ratio (WHtR). Participants were categorized according to the BMI z-score, WC, and WHtR international cut-off points as healthy and obese. Age- and sex-specific reference tables for the 3rd, 10th, 25th, 50th, 75th, 90th, and 97th centile scores were calculated using Cole’s lambda, mu, and sigma method. The prevalence of obesity according to the BMI z-score, WC, and WHtR was 9.6%, 11.2%, and 15.0%, respectively. Across all age and sex groups, a negative association was found between relative peak oxygen uptake (O2peak) and BMI, WC, and WHtR. In boys and girls there were higher levels of performance across all age groups, with most apparent gains between the ages of 13 and 14 years old. Overall, participants categorized in the healthy group had shown to have significantly higher O2peak than their obese counterparts (p < 0.001; Cohen’s d > 1.0). In conclusion, our study provides age- and sex-specific reference values for CRF (O2peak, mL·kg−1·min−1). The anthropometric parameters were inversely associated with CRF in all ages in both sexes. The obese group had worse CRF than their healthy counterparts independent of anthropometric parameters used to determine obesity.

A cross-sectional comparison between cardiorespiratory fitness, level of lesion and red blood cell distribution width in adults with chronic spinal cord injury

ObjectivesTo assess; (1) differences in red blood cell distribution width between individuals with chronic (>1year), motor-complete cervical (n=21), upper-thoracic (n=27) and thoracolumbar (n=15) spinal cord injury and, (2) associations between red blood cell distribution width and cardiorespiratory fitness. DesignProspective multi-center, cross-sectional study. MethodsPeak oxygen uptake was determined using an upper-body arm-crank exercise test to volitional exhaustion and red blood cell distribution width was measured using an automated hematology system. ResultsThere were significant (p<0.009) differences between groups classified by level of injury in absolute and relative peak oxygen uptake, peak power output and red blood cell distribution width. A significant (p<0.001) large negative association (r = −0.524) was found between relative peak oxygen uptake and red blood cell distribution width. Unbiased recursive partitioning, while revealing study site specific differences in red blood cell distribution width, identified homogenous subgroups based specifically on cardiorespiratory fitness irrespective of additional demographic and injury characteristics. ConclusionThe strong negative association between cardiorespiratory fitness and red blood cell distribution width in individuals with paraplegia parallel those previously observed in non-disabled individuals. Higher red blood cell distribution width values are an independent risk factor for increased cardiovascular mortality, heart failure, and coronary heart disease and may reflect several underlying exacerbated metabolic responses such as oxidative stress and systemic inflammation. These data emphasize the importance of maintaining a high aerobic capacity following spinal cord injury.

Cardiorespiratory Fitness Cut-Points are Related to Body Adiposity Parameters in Latin American Adolescents.

Background and Objectives: A deficiency exists in the criterion-referenced cut-points for field-based cardiorespiratory fitness (CRF) in Latin American youths. The aims of the present study were two-fold: (1) To identify the ability of CRF estimated by the 20-m shuttle-run test (20mSRT) to differentiate between “healthy” and “unhealthy” phenotypes (by adiposity) in adolescents; (2) to assess the association between obesity and relative peak oxygen uptake (VO2peak) in a large and diverse sample of Latin American youths. In total, 72,505 adolescents aged between 13 and 15 years were recruited from Chile and Colombia (47.5% girls). Materials and Methods: The waist circumference (WC) and waist-to-height ratio (WHtR) were used to identify body adiposity markers. CRF was measured using the 20mSRT (VO2peak). Receiver operating characteristic curves and logistic regression were used to determine the discriminatory ability of CRF to predict body adiposity parameters. Results: For boys and girls, VO2peak showed a significant predictive capacity to detect body fat (area under the curve [AUC] > 0.62). The sensitivity of VO2peak was medium (>63%) for all age- and sex-specific cut-points, with optimal cut-points in 13- to 15-year olds for obesity identified as 43.77 mL·kg−1·min−1 and 38.53 mL·kg−1·min−1 in boys and girls, respectively. Conclusions: According to these cut-points, adolescents with low CRF were more likely to be obese either by WC or WHtR. The CRF cut-points can be used as quantitative markers for a healthier body in Latin American adolescents.

Health‐related physical fitness and weight status in 13‐ to 15‐year‐old Latino adolescents. A pooled analysis

ObjectiveThe aim of this study was to investigate the relation between health‐related physical fitness and weight status in 13‐ to 15‐year‐old Latino adolescents. MethodThe final sample consisted of 73,561 adolescents aged 13–15 years (35,175 girls) from Chile (n=48,771) and Colombia (n=24,790). Cardiorespiratory and musculoskeletal fitness were measured using 20‐m shuttle run (relative peak oxygen uptake – VO2peak) and standing broad jump test (lower body explosive strength), respectively. The International Obesity Task Force definition was used to define weight status (i.e., underweight, normal weight, overweight, and obese). ResultsThe present study found an inverted J‐shape relationship between body mass index, cardiorespiratory fitness, and musculoskeletal fitness in both genders and all age groups (p<0.01). Results also suggest that underweight adolescents, and not just overweight and obese adolescents, have lower odds of having a healthy cardiorespiratory fitness (based on new international criterion‐referenced standards) profile when compared with their normal weight peers, except in girls aged 14 (p=0.268) and 15 years (p=0.280). ConclusionsThe present results indicate low cardiorespiratory fitness and musculoskeletal fitness levels in underweight, overweight, and obese adolescents when compared with their normal weight peers. The findings appear to suggest that exercise programs should to decrease fat mass in overweight/obese adolescents and increase muscle mass in underweight adolescents.

Health-related physical fitness and weight status in 13- to 15-year-old Latino adolescents. A pooled analysis

ObjectiveThe aim of this study was to investigate the relation between health-related physical fitness and weight status in 13- to 15-year-old Latino adolescents. MethodThe final sample consisted of 73,561 adolescents aged 13–15 years (35,175 girls) from Chile (n=48,771) and Colombia (n=24,790). Cardiorespiratory and musculoskeletal fitness were measured using 20-m shuttle run (relative peak oxygen uptake – VO2peak) and standing broad jump test (lower body explosive strength), respectively. The International Obesity Task Force definition was used to define weight status (i.e., underweight, normal weight, overweight, and obese). ResultsThe present study found an inverted J-shape relationship between body mass index, cardiorespiratory fitness, and musculoskeletal fitness in both genders and all age groups (p<0.01). Results also suggest that underweight adolescents, and not just overweight and obese adolescents, have lower odds of having a healthy cardiorespiratory fitness (based on new international criterion-referenced standards) profile when compared with their normal weight peers, except in girls aged 14 (p=0.268) and 15 years (p=0.280). ConclusionsThe present results indicate low cardiorespiratory fitness and musculoskeletal fitness levels in underweight, overweight, and obese adolescents when compared with their normal weight peers. The findings appear to suggest that exercise programs should to decrease fat mass in overweight/obese adolescents and increase muscle mass in underweight adolescents.

Temporal trends in the cardiorespiratory fitness of children and adolescents representing 19 high-income and upper middle-income countries between 1981 and 2014

ObjectiveTo estimate international and national temporal trends in the cardiorespiratory fitness (CRF) of children and adolescents and to examine relationships between temporal trends in CRF and temporal trends in broad...

Exercise Capacity and Functional Performance in Heart Failure Patients Supported by a Left Ventricular Assist Device at Discharge From Inpatient Rehabilitation.

Adequate physical and functional performance is an important prerequisite for renewed participation and integration in self-determined private and (where appropriate) professional lives following left ventricular assist device (LVAD) implantation. During cardiac rehabilitation (CR), individually adapted exercise programs aim to increase exercise capacity and functional performance. A retrospective analysis of cardiopulmonary exercise capacity and functional performance in LVAD patients at discharge from a cardiac rehabilitation program was conducted. The results from 68 LVAD patients (59 males, 9 females; 55.9 ± 11.7 years; 47 HVAD, 2 MVAD, 15 HeartMate II, 4 HeartMate 3, and 4 different implanting centers) were included in the analysis. Exercise capacity was assessed using a cardiopulmonary exercise test on a bicycle ergometer (ramp protocol; 10 W/min). The 6-min walk test was used to determine functional performance. At discharge from CR (53 ± 17 days after implantation), the mean peak work load achieved was 62.2 ± 19.3 W (38% of predicted values) or 0.79 ± 0.25 W/kg body weight. The mean cardiopulmonary exercise capacity (relative peak oxygen uptake) was 10.6 ± 5.3 mL/kg/min (37% of predicted values). The 6-min walk distance improved significantly during CR (325 ± 106 to 405 ± 77 m; P < 0.01). No adverse events were documented during CR. The results show that, even following LVAD implantation, cardiopulmonary exercise capacity remains considerably restricted. In contrast, functional performance, measured by the 6-min walk distance, reaches an acceptable level. Light everyday tasks seem to be realistically surmountable for patients, making discharge from inpatient rehabilitation possible. Long-term monitoring is required in order to evaluate the situation and how it develops further.

Functional Evaluation in Obese Patients Before and After Sleeve Gastrectomy.

Although sleeve gastrectomy (SG) has become an important treatment option in severe obesity, cardiorespiratory and muscle function after SG has not adequately been investigated. This is an observational study in 26 obese patients (BMI 45.2±5.8kg/m2), comparing physical function before and after 6months from SG. All available patients listed for SG were here included. Incremental cardiopulmonary exercise tests, standardized strength tests, and balance analysis were performed. The substantial weight loss (-33.4±11.0kg) after SG led to increased peak work capacity (metabolic equivalents, METs) and relative peak oxygen uptake (VO2peak/kg) (both p<0.001). However, the absolute VO2peak, oxygen pulse (VO2/heart rate (HR)), and the oxygen uptake efficiency slope (OUES) significantly declined after SG (all p<0.001). Furthermore, HR/VO2-slope significantly worsened after SG (p<0.001), whereas the HR reserve and HR recovery improved (all p≤0.01). Parameters of ventilatory efficiency were not affected by SG. The time-constant (Tau τ) of the fundamental component of VO2-kinetics, reflecting oxygen metabolism in skeletal muscles, was found to be significantly worsened after SG (p<0.05). Finally, muscle strength and balance parameters were not much affected by SG. The ventilatory and cardiac function do not appear negatively affected by SG; thus, we hypothesize that the decrease in aerobic capacity could be due to alterations in peripheral muscles. This might in part be due to a loss of muscle mass, although our patients' muscle strength did not decrease. Pilot results from VO2-kinetics analysis seem to support the hypothesis of a deterioration of oxidative muscle metabolism after SG.

Aerobic Power in Prepubescent Children with Different Levels of Physical Activity (Potencia Aeróbica en Niños Prepubescentes con Diferentes Niveles de Actividad Física)

The purpose of the study was to compare the aerobic power of prepubescent children (Tanner 1 stage). Participants were 95 children between 7 and 9 years old, divided into 4 physical activity level groups: a) Trained (n = 24), b) Sport beginners (n = 23), c) Active (n = 24), and d) Sedentary (n = 24). Physical activity level was determined by a three-day physical activity diary. Subjects performed a treadmill Balk protocol to obtain their peak oxygen uptake. Comparisons were made using ANOVA two-way and post hoc Tukey followed-up the significant differences for p&lt; 0,05. Trained, sport beginners and active children presented similar amount of physical activity level, but they significantly differ from the sedentary children (p&lt; 0.05). Overall boys (50.67 ± 8.52 ml/kg/min) had higher relative peak oxygen uptake than girls (45.19 ± 6.44 ml/kg/min). The gender by group interaction showed that this difference is explained by the superior values of the trained boys (58.80 ± 8.98 ml/kg/min) when compared to trained girls (47.51 ± 5.68 ml/kg/min), even though they presented the same amount of physical activity level. The trained group (53.16 ± 9.34 ml/kg/min) showed higher relative peak oxygen uptake compared to sport beginners (48.90 ± 6.54 ml/kg/min), active children (45.46 ± 7.50 ml/kg/min) and sedentary children (44.63 ± 9.52 ml/kg/min). The results suggest that prepubescent children that participate in systematized trained programs have better physiological indicators for aerobic fitness.Key words. aerobic power, physical activity, children.Resumen. El propósito del estudio fue comparar la potencia aeróbica de niños prepubescentes (Estadio de Tanner 1). Participaron 95 niños y niñas con edades entre 7 y 9 años, divididos en 4 grupos basados en sus niveles de actividad física: a) Entrenados (n = 24), b) Principiantes en deportes (n = 23), c) Activos (n = 24), y d) Sedentarios (n = 24). Los niveles de actividad física se determinaron por medio de un diario de actividad física de tres días. Los participantes realizaron el protocolo de Balke en banda sin fin para obtener el consumo de oxígeno pico. Se hicieron comparaciones con ANOVA de dos vías y post hoc de Tukey cuando se encontraron diferencias significativas a un p &lt; 0.05. Los niños prepubescentes entrenados, principiantes en deportes y activos presentaron niveles de actividad física similares, pero fueron significativamente diferentes de los niños sedentarios (p &lt; 0.05). En general, los niños presentaron mayor consumo de oxígeno pico (50.67 ± 8.52 ml/kg/min) que las niñas (45.19 ± 6.44 ml/kg/min). La interacción de sexo por grupo mostró que esta diferencia se explica por el mayor valor de los niños entrenados (58.80 ± 8.98 ml/kg/min) cuando se les comparó con las niñas entrenadas (47.51 ± 5.68 ml/kg/min), aunque tuvieran el mismo nivel de actividad física. El grupo entrenado (53.16 ± 9.34 ml/kg/min) presentó mayores valores de consumo de oxígeno pico comparados con los principiantes (48.90 ± 6.54 ml/kg/min), niños activos (45.46 ± 7.50 ml/kg/min) y niños sedentarios (44.63 ± 9.52 ml/kg/min). Los resultados sugieren que los niños prepubescentes que participan en programas de entrenamiento sistemáticos tienen mejores indicadores fisiológicos de capacidad aeróbica.Palabras claves. potencia aeróbica, actividad física, niños

Acute effects of an arginine-based supplement on neuromuscular, ventilatory, and metabolic fatigue thresholds during cycle ergometry.

The purpose of the present study was to examine the effects of an acute dose of an arginine-based supplement on the physical working capacity at the fatigue threshold (PWCFT), lactate threshold (LT), ventilatory threshold (VT), and peak oxygen uptake during incremental cycle ergometry. This study used a double-blinded, placebo-controlled, within-subjects crossover design. Nineteen untrained men (mean age ± SD = 22.0 ± 1.7 years) were randomly assigned to ingest either the supplement (3.0 g of arginine, 300 mg of grape seed extract, and 300 mg of polyethylene glycol) or placebo (microcrystalline cellulose) and performed an incremental test on a cycle ergometer for determination of PWCFT, LT, VT, and peak oxygen uptake. Following a 1-week period, the subjects returned to the laboratory and ingested the opposite substance (either supplement or placebo) prior to completing another incremental test to be reassessed for PWCFT, LT, VT, and peak oxygen uptake. The paired-samples t tests indicated there were significant (P < 0.05) mean differences between the arginine and placebo conditions for the PWCFT (192 ± 42 vs. 168 ± 53 W, respectively) and VT (2546 ± 313 vs. 2452 ± 342 mL·min(-1)), but not the LT (135 ± 26 vs. 138 ± 22 W), absolute peak oxygen uptake (3663 ± 445 vs. 3645 ± 438 mL·min(-1)), or relative peak oxygen uptake (46.5 ± 6.0 vs. 46.2 ± 5.0 mL·kg(-1)·min(-1)). These findings suggested that the arginine-based supplement may be used on an acute basis for delaying the onset of neuromuscular fatigue (i.e., PWCFT) and improving the VT in untrained individuals.

Hormonal, metabolic, and cardiorespiratory responses of young and adult athletes to a single session of high-intensity cycle exercise.

This study aimed to determine the effects of a single high-intensity interval training (HIIT) session on salivary cortisol (SC) levels, physiological responses, and performance in trained boys and men. Twenty-three boys (11.5 ± 0.8 years) and 25 men (29.7 ± 4.6 years) performed HIIT (4 consecutive Wingate Anaerobic Tests). SC in boys and men increased after HIIT from 5.55 ± 3.3 nmol/l to 15.13 ± 9.7 nmol/l (+173%) and from 7.07 ± 4.7 nmol/l to 19.19 ± 12.7 nmol/l (+171%), respectively (p < .01). Pretest SC as well as posttest changes were comparable in both groups (both p < .01). Peak blood lactate concentration was significantly lower in boys (12.6 ± 3.5 mmol/l) than in men (16.3 ± 3.1 mmol/l; p < .01). Throughout the HIIT, mean heart rates in boys were higher (p < .001) but relative peak oxygen uptake (ml·min-1·kg-1; p < .05) and performance were lower (p < .001) in boys than in men. HIIT in young athletes is associated with a higher activation of the hormonal stress axis than other types of exercise regimes as described in the literature. This study is the first to show a pronounced SC increase to HIIT in trained boys accompanied by elevated levels of blood lactate concentrations and heart rate suggesting a high cardio-respiratory, metabolic, and hormonal response to HIIT in 11-year-old boys.

Comparison of the effects of weight loss from a high-protein versus standard-protein energy-restricted diet on strength and aerobic capacity in overweight and obese men

To compare the effects of two low-fat, hypoenergetic diets differing in carbohydrate-to-protein ratio, on strength and aerobic capacity measures in overweight and obese men. In a parallel design, 56 men (age, 45.5 ± 8.7 years; BMI, 33.6 ± 3.9 kg/m(2)) were randomly assigned to a low-fat, energy-restricted diet (7,000 kJ/day) with either high protein (HP: protein/carbohydrate/fat % energy, 35:40:25) or standard protein (SP, 17:58:25). Body weight, body composition, muscle strength and aerobic capacity were assessed at baseline and after 12 weeks. Forty-two participants completed the study (HP, n = 21; SP, n = 21). Both groups experienced similar reductions in body weight (HP, -10.7 ± 5.3 kg [-9.8%]; SP, -8.7 ± 3.5 kg [-8.4%]) and fat-free mass (HP, -2.8 ± 3.6 kg; SP, -3.2 ± 2.7 kg; P < 0.001 time; P > 0.14 time × group interaction). There was a trend for a greater reduction in fat mass in the HP diet group, (-7.7 ± 4.3 kg [-21.2%] vs. -5.4 ± 3.3 kg [-15.1%]; P < 0.001 time; P = 0.06 time × group interaction). Absolute peak oxygen uptake did not change in either group (P = 0.39 time; P = 0.50 time × group interaction). Overall, in both groups, relative peak oxygen uptake increased (2.9 ± 2.8 ml kg(-1) min(-1) [8.9%]), peak isometric knee extensor strength increased (14.1 ± 35.7 Nm [7.1%]) and peak handgrip strength decreased (-1.6 ± 4.1 kg [-3%]) (P ≤ 0.02 time for all), with no diet effect (P ≤ 0.23 time × group interaction). In overweight and obese men, both a HP and SP diet reduced body weight and improved body composition with similar effects on strength and aerobic capacity.

Rapid Communication – Effect of Exercise Training on Asymmetric Dimethylarginine Concentration in Women Aged 65-74 years with Type 2 Diabetes

Aims/hypothesis: Basal plasma concentration of asymmetric dimethylarginine (ADMA), an endogenous, competitive inhibitor of nitric oxide synthase, is elevated in patients with type 2 diabetes. ADMA may contribute to the endothelial dysfunction and associated vascular complications observed in individuals with type 2 diabetes. The present study investigated the effect of 12 weeks of supervised walking exercise on plasma ADMA concentration in women aged 65-74 years with type 2 diabetes. Materials and methods: Fourteen women (aged 69 ± 3 yrs) with uncomplicated type 2 diabetes, completed 12 weeks of supervised, moderate-intensity walking at an intensity equivalent to their individual gas-exchange threshold. Blood was sampled for ADMA concentration before and after a 6-week intervention-free control period, and again after 6 and 12 weeks of exercise training. Results: Plasma ADMA concentration was found to be significantly lower after 12-weeks of exercise training when compared with baseline (0 wk) measurements. These results were accompanied by significant increases in time to exhaustion, relative and absolute peak oxygen uptake, and oxygen uptake at gas-exchange threshold. Conclusion/interpretation: Regular, moderate-intensity exercise decreases circulating ADMA concentrations in older women with type 2 diabetes. These results suggest that ADMA may play a role in the training-induced reduction in cardiovascular disease risk seen with exercise training in individuals with type 2 Diabetes.

Reproducibility, validity and predictors of six-minute walk test in overweight and obese adolescents with intellectual disability

Objectives: To assess the reproducibility and validity of the six-minute walk test (6MWT) and predictors of the six-minute walk distance (6MWD) in adolescents with overweight or obesity and intellectual disability (ID). Study design: Sixty-one adolescents with overweight or obesity and mild-to-moderate ID (intelligent quotient [IQ] 40–70; age 14–22 years) participated in this study. To test reproducibility, 39 of the participants performed the 6MWT twice with an interval of 1 week. To test validity (n = 39), peak oxygen uptake (peak VO2) was measured on a bicycle ergometer. For the predictor study (n = 61), weight, height, peak VO2 and quadriceps strength were measured, and IQ and orthopedic conditions were collected from the participants’ medical records. Results: There was no significant difference between the means of the two 6MWTs (571.3 vs. 576.5 m; p = 0.452). The intraclass correlation coefficient was 0.82, indicating good reliability. The smallest real difference was 82.6 m. 6MWD correlated significantly with relative peak VO2 (β = 0.69) indicating validity. Relative peak VO2, height, IQ, body mass index (BMI) and quadriceps strength are predictors of the 6MWD in this population. Conclusion: 6MWT is a reliable and valid test in adolescents with overweight or obesity and ID. Low IQ, overweight/obesity and low physical fitness contribute to the outcome of the 6MWT.Implications for RehabilitationThe six-minute walk test (6MWT) with continuous verbal encouragement is a valid and reliable field test in a population of adolescents with overweight and intellectual disability (ID).The main variables associated with the six-minute walk distance in this specific population are relative peak oxygen uptake (VO2), height, intelligent quotient (IQ), body mass index and quadriceps strength.Specific characteristics of a population with ID (low IQ, higher prevalence of overweight, lower physical fitness) are contributing largely to the outcome of the 6MWT and thereby makes this test interesting for clinical use.