Submaximal Oxygen Consumption Research Articles

Beetroot juice supplementation and exercise performance: is there more to the story than just nitrate?

This mini-review summarizes the comparative effects of different sources of dietary nitrate (NO3-), beetroot juice (BRJ) and nitrate salts (NIT), on physiological function and exercise capacity. Our objectives were to determine whether BRJ is superior to NIT in enhancing exercise-related outcomes, and to explore the potential contribution of other putatively beneficial compounds in BRJ beyond NO3-. We conducted a comparative analysis of recent studies focused on the impact of BRJ versus NIT on submaximal oxygen consumption (VO2), endurance performance, adaptations to training, and recovery from muscle-damaging exercise. While both NO3- sources provide benefits, there is some evidence that BRJ may offer additional advantages, specifically in reducing VO2 during high-intensity exercise, magnifying performance improvements with training, and improving recovery post-exercise. These reported differences could be due to the hypothesized antioxidant and/or anti-inflammatory properties of BRJ resulting from the rich spectrum of phytonutrients it contains. However, significant limitations to published studies directly comparing BRJ and NIT make it quite challenging to draw any firm conclusions. We provide recommendations to help guide further research into the important question of whether there is more to the story of BRJ than just NO3-.

Characteristics of walking techniques with different pelvic height and pelvic rotation: effect on muscle activation and energy consumption.

Purpose: Previous studies have proven that modifications in the natural walking technique alter muscle activation and energy consumption. This research aimed to determine the differences in muscle activation, energy consumption, kinematic characteristics, perceived muscular exertion and perceived cardio-respiratory fatigue between natural and modified walking techniques with altered pelvic height and rotation. Methods: Nine physically active, non-injured males walked on a treadmill. Modified walking techniques assumed maintenance of constant pelvic height and application of maximal pelvic rotation. Walking speed was subtransit - 0.4 km/h less than the transit. Sampled variables were: average normalized maximal activation during contact and swing phase relativized to maximal voluntary activation, average submaximal oxygen consumption relativized to body mass and subtransit speed, average step length and frequency, rating of perceived muscular exertion and perceived cardio-respiratory fatigue. Muscle activation, energy consumption and kinematic characteristics were assessed throughout each walking session. Perceived muscular exertion and perceived cardio-respiratory fatigue were evaluated post-session. Electromyographic activity was assessed for rectus femoris, gluteus maximus, vastus medialis, biceps femoris, tibialis anterior and gastrocnemius lateralis. Results: The most significant changes in muscle activation were observed during the contact phase. A decrease in pelvic height increased muscle activation of rectus femoris, vastus medialis and gastrocnemius lateralis. An increase in pelvic rotation increased muscle activation of all monitored muscles except for gluteus maximus. Both modifications increased energy consumption, perceived muscular exertion and perceived cardio-respiratory fatigue, and altered kinematic characteristics. Conclusions: Modifications in pelvic height and rotation at the same walking speed alter muscle activation, energy consumption, kinematic characteristics, perceived exertion and fatigue.

A COMPARISON OF REPEATED WINGATE BASED OF HIGH INTENSITY INTERVAL TRAINING AND MODERATE INTENSITY CONTINUOUS TRAINING ON AEROBIC CAPACITY UNDER NORMOBARIC HYPOXIA

Aerobic capacity is very important for all people in terms of health and performance. Therefore, important organizations such as the World Health Organization (WHO) and the American College of Sports Medicine (ACSM) generally recommend that adults should perform physical activity maintain and improve their aerobic capacity. This study aimed to compare the effects of 8-week Repeated Wingate (RW) based of high-intensity interval training (HIIT) vs. moderate-intensity continuous training (MICT) on the aerobic fitness in recreationally active young adults under hypoxic and normoxic conditions. Thirty-two recreationally active young adults (age:22,37±2,30 years) were randomly assigned to Hypoxia RW(n=8), Normoxia RW(n=8), Hypoxia MICT (n=8), Normoxia MICT (n=8) group training protocol. The HIIT groups consisted of 4-7×30-s Wingate “all-out” sprints with 4 min of passive rest. The MICT groups completed 25-40 minutes of continuous running. Before, 4-week and after the 8-week interventions the following tests were completed: maximum oxygen consumption (V̇O2max), anaerobic threshold oxygen consumption (AT VO2), time to exhaustion (TTE) be determined from the Bruce treadmill protocol and submaximal oxygen consumption (Submaximal VO2) be determined from the modified Astrand protocol. Statistical difference was found between the 4th and 8th weeks in the HIIT and MICT groups according to the pre-tests (p ≤ 0.05). However, no difference was found between the condition (Hypoxia - Normoxia) and training methods (HIIT-MICT) (p ≤ 0.05).

Comparison of the Effects of Two Exercise Programs of High-intensity Interval Training and Moderate-intensity Continuous Training on Physiological Function of Heart Patients after Coronary Artery Bypass Graft Surgery

Background: Exercise-based cardiac rehabilitation(CR) programs increase physiological function. However, it’s not yet clear which feature of exercise is most effective in improving important physiological performance indicators in heart patients. Therefore, the aim of this study was to compare the effects of high-intensity interval training(HIT) and moderate-intensity continuous training(MCT) on metabolic equivalent of tasks(METs), submaximal myocardial oxygen consumption(MVO2submax), and heart rate recovery(HRR) of heart patients after coronary artery bypass graft(CABG) surgery. Methods: Twenty-four post-CABG patients (15 males and 9 females) with a mean age of 60.75±3.16 years and a mean body mass index (BMI) of 28.40±1.09 kg/m2 were randomly divided into three groups of HIT, MCT and control group (CG). The training groups (HIT and MCT) trained for eight-weeks, three-sessions per week, and 45minutes per session. The research variables (METs, MVO2submax and HRR) were measured and compared in two stages before and after eight-weeks of CR programs. Results: After eight-weeks of CR programs, patients in both training groups showed a significant improvement in METs, MVO2submax and HRR (P<0.05), and the HIT group showed significantly greater improvement in METs (P=0.001) and HRR (P=0.001) compared to the MCT group, as well the MCT group showed a significantly more improvement in MVO2submax (P=0.001) than the HIT group. Also, no cardiovascular adverse events related to HIT or MCT occurred during the implementation of the study. Conclusion: According to the results of the present study, HIT seems to be more effective than MCT in improving METs and HRR of post-CABG patients, and is safe as well.

The informative power of heart rate along with machine learning regression models to predict maximal oxygen consumption and maximal workload capacity

Prediction of maximal oxygen consumption (VO2max) and maximal workload capacity (MWC) through submaximal exercise tests is an important topic for sports sciences. Numerous studies highlighted the predictive power of submaximal heart rate (HR) and oxygen consumption (VO2) in predicting VO2max and MWC. The challenge is achieving the best possible precision and accuracy by identifying the best predictors and regression models. This project assessed the performance of different indexes along with machine learning regression models to estimate VO2max and MWC. Predictors consisted of biodata (age, weight, and height) along with different combinations of change-scores of HR and VO2 between 0–50 Watts, 50–65 Watts, and 65–80 Watts (Δ0–50, Δ50–65, and Δ65–80, respectively). The use of biodata + HR Δ50–65 + HR Δ65-80 via a Squared Exponential Gaussian Process Regression model resulted in the best performance in predicting VO2max, while the use of biodata + HR Δ0–50 via a Robust Linear Regression model resulted in the best performance in predicting MWC. These results suggest that information provided by HR only during submaximal exercise offers the best predictive mean for estimating VO2max and MWC, while the use of VO2 changes or its addition along with HR changes does not improve predictions. Moreover, different predictors need to be selected for the best estimation of VO2max and MWC. Change-scores refer to absolute value changes, providing information to develop athlete assessment protocols through standardized workloads. These results show practical applicability for sports assessments to be performed indirectly, rapidly, sub-maximally, and through the simple measurement of HR.

A Novel Custom Cycle Ergometer Protocol to Determine V̇O2max: Validation with ACSM’s Cycle Ergometry Metabolic Equation

ABSTRACT Introduction Protocols for determination of maximal oxygen consumption (V̇O2max) on a cycle ergometer should be easily administered while maximizing physiological efficiency and minimizing premature local muscle fatigue for individuals of variable fitness levels. Current protocols typically increase workload by adding resistance to the flywheel; however, increasing pedal rate later in the test, rather than resistance, may provide increased physiological efficiency, yielding a more valid determination of V̇O2max. Purpose The purpose of this study was to design and validate a novel V̇O2max cycle ergometer protocol that can be used for measuring and predicting submaximal oxygen consumption (V̇O2) and V̇O2max during exercise testing in healthy, asymptomatic adults. Methods Subjects (n = 60, 19–60 yr old) performed a V̇O2max test using the new cycle ergometer protocol. Workload increases were based on predetermined incremental target heart rates (ITHR) using heart rate reserve. Stages commenced at a workload of 150 kg·m·min−1 (0.5 kg, 50 rpm) and increased every 2 min by adding 0.5 or 1.0 kg resistance based on ITHR. When an ITHR representing ≥60% heart rate reserve was achieved, workloads increased by 10 rpm for subsequent stages. Pearson’s r was used to examine relationships between predicted (American College of Sports Medicine cycle equation) and measured V̇O2 at workload intensities representing moderate, vigorous, and maximal exercise. Bland–Altman plots were used to display predicted and measured V̇O2 at all exercise intensities and heart rate values at maximal exercise. Results There was a strong and statistically significant correlation between predicted and measured V̇O2 at moderate (r = 0.92, P < 0.001), vigorous (r = 0.94, P < 0.001), and maximal (r = 0.90, P < 0.001) exercise intensities. All subjects reached ≥90% of age-predicted maximum heart rate. Conclusion This novel cycle ergometer protocol was demonstrated to be a viable tool to predict and/or measure submaximal V̇O2 and V̇O2max in a population of healthy, asymptomatic adults.

Pilot Project: Heart Chargers-A Successful Model for a Home-Based Physical Activity Program Utilizing Telemedicine for Fontan Patients.

Fontan patients have decreased exercise capacity which further declines throughout adolescence. A positive exercise capacity trajectory in children predicts better adult Fontan outcomes. Hospital-based physical activity programs improve exercise capacity and attenuate the age-expected decline in Fontan patients. The purpose of this project was to investigate the feasibility and safety of a partially reimbursable 12-month, home-based, individualized physical activity program (Heart Chargers) for Fontan patients utilizing telemedicine. The Heart Chargers team included a cardiologist, nurse coordinator, and exercise physiologists. Eligible participants with a Fontan completed a baseline cardiopulmonary exercise test (CPET) and consented to participate in Heart Chargers, a 12-month home-based exercise prescription. The individualized exercise prescription focused on skeletal and respiratory muscle strength training and aerobic activities. Participants received a Garmin© device to monitor adherence. Telephone check-ins ranged from weekly to monthly as participants gained independence. Pre- and post-program CPET and informal surveys of physical activity self-efficacy were completed. Nine participants have completed the Heart Chargers program. There was no pre-postdifference in maximal or submaximal oxygen consumption (VO2), peak heart rate, or oxygen saturation. There was a significant pre-post increase in systolic blood pressure (p-value 0.004) and minute ventilation (p-value 0.012) at peak exercise. Per subjective report, exercise-related self-efficacy increased after program completion. There were no adverse events. At present, 7 participants remain actively enrolled in the program. Heart Chargers, a novel, home-based, partially reimbursable, 12-month individualized exercise program using telemedicine was successfully implemented in Fontan patients with no adverse events. The lack of decline in exercise capacity for participants is encouraging.

Pedaling cadence does not affect aerobic performance during an incremental maximal test among male and female adult cyclists

The purpose of the study was to evaluate the effect of pedaling at the energetically optimal cadence (EOC) on aerobic capacity and cycling efficiency in experienced male and female adult cyclists. Twenty-four experienced cyclists underwent a progressive, maximal metabolic exercise test on a cycling ergometer pedaling at their freely chosen cadence (FCC). EOC was determined by maintaining an output of 65% of peak power during seven consecutive 3-minute stages of cadences between 50 rpm to 110 rpm in 10 rpm increments in a randomized order. Cyclists were then randomized to either an FCC or EOC group and performed a second maximal exercise test. Oxygen consumption (VO2max), time to exhaustion (Tmax), ventilatory threshold (VO2VT) and time to ventilatory threshold (TVT) were compared between the FCC and EOC groups. Submaximal average oxygen consumption was significantly higher during FCC (85±11 rpm) than EOC (60±8 rpm; 38.2±6.64 ml/kg/min v. 35±7.7 ml/kg/min, p<0.001). There were no significant interactions between group and order of maximal exercise tests with respect to VO2max (b=1.59, p=0.38), Tmax (b=0.31, p=0.55), VO2VT (b=0.05, p=0.98) or TVT (b=0.18, p=0.82). FCC was significantly lower among female cyclists compared to male cyclists. We conclude that cycling at EOC at submaximal workloads demands less oxygen consumption than FCC, but does not significantly improve VO2max, and that there may be sex-specific differences with regards to FCC among experienced adult cyclists.

Abstract 15762: Model for Home-Based Physical Activity Program Utilizing Telemedicine for Fontan Patients

Introduction: Fontan patients have decreased exercise capacity. The COVID-19 pandemic exacerbated the variable adherence to hospital-based physical activity programs, which improve exercise capacity and attenuate the expected decline in aging Fontan patients. A positive pediatric exercise capacity trajectory has been reported to predict better adult Fontan outcomes. We designed and implemented a reimbursable 12-month, home-based, individualized physical activity program for Fontan patients utilizing a telemedicine model. Methods: Eligible participants must be able to complete a cardiopulmonary exercise test (CPET) and demonstrate ability to adhere to a 12-month exercise prescription. Assent and consent are obtained. CPET and informal surveys of physical activity self-efficacy are completed at enrollment and graduation. An individualized exercise prescription is provided, with focus on skeletal and respiratory muscle strength training and aerobic activities. Participants receive a Garmin© device to monitor adherence. A cardiologist, nurse coordinator, and exercise physiologists comprise the team and regularly communicate with participants, starting with weekly check-ins that gradually space out to monthly as participants gain confidence. Results: Since program initiation, 9 participants have completed the program and 3 remain active. For the 9 graduates, all scheduled in-person and telehealth visits were completed. At completion of the 12-month program compared to baseline, there was no difference in maximal or submaximal oxygen consumption (VO2), peak heart rate, or oxygen saturation, but there was a significant increase in systolic blood pressure (144 ± 16 vs 162 ± 15, p-value 0.004) and minute ventilation (68.8 ± 19.3 vs 76.8 ± 22.1, p-value 0.012) at peak exercise. Per subjective report, all graduates had increased confidence related to exercise. There were no adverse events in any participant. Conclusions: A novel, home-based, 12-month individualized physical activity program using telemedicine was successfully implemented, with no adverse events. A larger study is needed to better assess change in VO2 and other qualitative and quantitative parameters, although the lack of decline in exercise capacity is encouraging.

Metabolic adaptation after combined resistance and aerobic exercise training in older women.

This study investigated whether combined aerobic and resistance training in older women leads to metabolic adaptation. A total of 80 women (64 White individuals; BMI: 30.0[4.4]kg/m2 ; age: 64.8[3.5]years) followed 32 weeks of aerobic and resistance training. Body weight/composition (dual-energy X-ray absorptiometry) and resting metabolic rate (RMR; indirect calorimetry) were measured at baseline, week 16, and week 32. Metabolic adaptation was defined as significantly lower measured versus predicted RMR. A regression model to predict metabolic adaptation was developed that included race, age, baseline fat-free mass, RMR and respiratory quotient, and changes in net submaximal oxygen consumption after different tasks. There was significant metabolic adaptation at week 16 (-59[136]kcal/d, p=0.002), following a 640-kcal/wk energy loss (-0.7[2.6]kg of weight loss). In 53 women with complete data, metabolic adaptation was seen both at week 16 (-64[129]kcal/d, p=0.001) and at week 32 (-94[127]kcal/d, p < 0.001). Metabolic adaptation at week 16 was predicted by race, age, baseline fat-free mass, RMR and respiratory quotient, and change in net oxygen consumption of walking (R2 adjusted=0.90, p < 0.001). Similar results were seen at week 32. In older women with overweight and obesity, a minimal energy deficit induced by aerobic and resistance exercise is associated with metabolic adaptation at the level of RMR.

Alternative Metabolic Strategies are Employed by Endurance Runners of Different Body Sizes; Implications for Human Evolution

ObjectiveA suite of adaptations facilitating endurance running (ER) evolved within the hominin lineage. This may have improved our ability to reach scavenging sites before competitors, or to hunt prey over long distances. Running economy (RE) is a key determinant of endurance running performance, and depends largely on the magnitude of force required to support body mass. However, numerous environmental factors influence body mass, thereby significantly affecting RE. This study tested the hypothesis that alternative metabolic strategies may have emerged to enable ER in individuals with larger body mass and poor RE.MethodsA cohort of male (n = 25) and female (n = 19) ultra-endurance runners completed submaximal and exhaustive treadmill protocols to determine RE, and V̇O2Max.ResultsBody mass was positively associated with sub-maximal oxygen consumption at both LT1 (male r=0.66, p<0.001; female LT1 r=0.23, p=0.177) and LT2 (male r=0.59, p=0.001; female r=0.23, p=0.183) and also with V̇O2Max (male r=0.60, p=0.001; female r=0.41, p=0.046). Additionally, sub-maximal oxygen consumption varied positively with V̇O2Max in both male (LT1 r=0.54, p=0.003; LT2 r=0.77, p<0.001) and female athletes (LT1 r=0.88, p<0.001; LT2 r=0.92, p<0.001).ConclusionsThe results suggest that, while individuals with low mass and good RE can glide economically as they run, larger individuals can compensate for the negative effects their mass has on RE by increasing their capacity to consume oxygen. The elevated energy expenditure of this low-economy high-energy turnover approach to ER may bring costs associated with energy diversion away from other physiological processes, however.

Energy System Contribution during 1500M Running in Untrained and Endurance-Trained Asian Male College Students

OBJECTIVES To compare the aerobic and anaerobic energy system contribution during 1500m running between collegiate untrained (UT) and endurance trained (ET) subjects.METHODS Five Asian UT (age: 23.8 ± 0.4 yrs, body fat %: 15.9 ± 5.7 %, height: 174.0 ± 4.1 cm, weight: 65.5 ± 4.1 kg) and 5 Asian ET male participants (age: 24.4 ± 3.9 yrs, body fat %: 12.9 ± 6.9 %, height: 169.4 ± 5.1 cm, weight: 60.6 ± 8.1 kg) participated in this study. Participants attended 3 sessions to determine their body composition, submaximal and maximal oxygen consumption (VO2max) test, 1500m track running session (RS) and 1500m treadmill RS. The maximally accumulated oxygen deficit (MAOD) method was used to calculate energy system contribution.RESULTS The times for the 1500m track run for the UT and ET were 428.0 ± 48.7 and 331.6 ± 14.0 seconds (p=0.004) respectively. There were no significant differences in VO2 between the 1500m track and treadmill RS indicating the participants ran to their personal best times for both trials. The mean VO2max(mL•kg-1•min-1) were significantly different between UT (45.1 ± 5.0) and ET participants (58.3 ± 2.2) (p=0.002). The mean relative contributions of the aerobic and anaerobic energy system during 1500m running were significantly different for the UT, 65.4 ± 7.0%, 34.6 ± 7.0 and ET, 75.7 ± 1.5%, 24.3 ± 1.5 % (p =0.011).CONCLUSIONS The point of equal contribution of the aerobic and the anaerobic systems occurred after thirty to forty seconds of intensive exhaustive running after which the aerobic contribution continues to increase while the anaerobic contribution decreases with increasing duration. By the end of 60th second of exhaustive running, the ET mean aerobic contribution is 71.5% compared to the UT’s 58.6%. This finding suggests a greater reliance on the aerobic energy system by the ET.

Effect of Foot Orthoses on Running Economy and Foot Longitudinal Arch Motion in Runners With Flat-Arched Feet.

To determine the effect of manipulating foot longitudinal arch motion with different-stiffness foot orthoses on running economy (RE) in runners with flat-arched feet and if changes in arch deformation and recoil were associated with changes in RE. Twenty-three recreational distance runners performed 5-minute submaximal treadmill runs at 12km·h-1, in the following 3 conditions in a randomized order: (1)footwear only, (2)flexible orthoses (reduced arch thickness), and (3)standard orthoses. The RE (submaximal steady-state oxygen consumption [VO2submax]) and sagittal arch range of motion were compared among conditions using a repeated-measures analysis of variance and effect sizes (Cohen d). Pearson correlation coefficients were used to determine the association between the change in the sagittal arch range of motion and VO2submax. Compared with standard orthoses, the mean VO2submax was significantly lower in both the flexible orthoses (-0.8mL·kg-1·min-1, P < .001, d = 0.35) and footwear-only conditions (-1.2mL·kg-1·min-1, P < .001, d = 0.49). The change in VO2submax between the flexible orthoses and footwear-only conditions was significantly positively correlated with the change in sagittal arch range of motion (r = .591, P = .005). Conventional foot orthoses were associated with poorer RE compared with flexible orthoses and footwear alone. Changes in arch deformation were positively correlated to changes in oxygen consumption, indicating that foot orthoses that limit arch deformation and recoil degrade RE. Foot orthoses that facilitate energy storage and release in the foot longitudinal arch may be advisable for athletes prescribed these devices for clinical purposes to maintain optimal running performance.

PARAMETERS OF FUNCTIONAL ABILITIES IN RUNNING – RESEARCH REVIEW

Running as an athletic discipline requires a high level of endurance and speed endurance, which is directly related to the cardiovascular and respiratory systems, ie the ability of an athlete's body to withstand loads, and the following are listed as relevant factors for running success: anaerobic strength and maximum O2 consumption, lactic acid concentration and oxygen deficiency, ability to withstand stress, high ability to concentrate and its retention over longer periods of time. There is a lot of research that has studied the parameters of functional abilities in an attempt to find the most effective way to improve them, and since there are many similar and different data on this topic, this paper has been done to classify the available papsers by domestic and foreign authors which would lead to conclusions applicable both in practice and for further research.For the purposes of this research, original scientific papers have been analyzed that dealt with functional abilities as success factors in short, middle and long distance running and the impact of training on functional abilities, found in electronic databases - Medline, PubMed, Researchgate, Web of Science and Google Scholar. The research used in this review monitored transversely the values ​​of submaximal and maximal oxygen consumption, energy systems, heart rate values, pulmonary ventilation, blood lactate concentration, as well as their changes after longitudinal implementation of experimental protocols and training processes. Since the collected research had too few respondents from different populations with a small number of elite runners, and they did not have enough information about many years of experience, level of sports form, race categories, and descriptions of training and methods, obtaining empirical information based on evidence was limited, as well as reaching valid conclusions. Accordingly, there is a need for a more systematic approach to research and implementation of complex studies with a sufficient number of runners of all ages, both sexes of the elite level, and cooperation of academic researchers, clubs and athletes to enable studies that would provide significant statistics, analysis and interpretation. The results identified in this review provide a starting point for future research that identifies and quantifies predictors of functional.

수정된 퀸즈칼리지 스텝 검사의 최대산소 섭취량에 대한 상관관계 분석

The purpose of this study was to find correlations among the Queen’s college step test, modified Queen’s college step test, graded exercise test to predict 85% VO2max. Sixteen University students volunteered for this study. All participants were assessed by three tests. The data were analyzed using one way repeated analysis of variance, and Pearson product moment correlation. The results revealed that estimated VO2max values were significantly different among the three assessments (p<.05). In post-hoc test, the Queen’s college step test value was higher than other two tests. However, there was no significant difference between modified Queen’s college step test and graded exercise test (p>.05). In addition, graded exercise test had a significant correlation with the modified Queen’s college step test (p<.05). Therefore, modified Queen’s college step test may be considered as an appropriate assessment tool to predict submaximal oxygen consumption of normal adults.

Abstract P216: Co-ingestion of Dietary Nitrate and Caffeine Elevates Submaximal Oxygen Consumption and Oxygen-pulse Compared to Nitrate or Caffeine Alone

Introduction: Previous studies have examined dietary nitrate's and caffeine’s combined effects on time-trial and peak power output with caffeine improving performance while nitrate exhibits no additive benefit with co-ingestion. However, less is known about their combined effect on submaximal intensity exercise. Dietary nitrate may reduce submaximal oxygen cost while caffeine may increase submaximal cost. Hypothesis: Co-ingestion of dietary nitrate may attenuate the rise in oxygen consumption following caffeine intake. Methods: Ten healthy individuals (4 males; 28 ± 10 years of age) and (6 females; 21 ± 3 years of age) participated in a double-blind, placebo controlled, crossover experiment. The first of five visits consisted of a maximal oxygen consumption (VO 2max ) treadmill test. Prior to visits 2 - 5, participants consumed either a dietary nitrate (~12.4 mmol, NIT) or placebo nitrate supplement (PLN) combined with either a caffeine (3 mg/kg, CAF) or placebo caffeine (PLC) dose for a total of 4 days. The final dose of NIT or PLN and CAF or PLC was consumed 2.5 and 1-hr pre-exercise, respectively. Visits 2 - 5 consisted of a 30-min treadmill run at ~65% VO 2max . During exercise, VO 2 and heart rate (HR) were measured continuously. A linear mixed effects model analysis was performed to determine how each supplementation influenced each dependent variable. Treatments (NIT+CAF, CAF+PLN, NIT+PLC, PLN+PLC) and exercise timepoints (10 and 30 min) served as fixed factors. If p&lt;0.05, p ost-hoc pairwise comparisons were performed. Results: Exercise VO 2 was significantly elevated for NIT+CAF at 10 and 30 minutes (36.2±4.1 and 37.7±5.0 ml/kg/min, respectively) compared to placebo (33.4±3.4 and 35.3±3.8 ml/kg/min, respectively) (p&lt;0.05). However, there was no difference in VO2 at either timepoint (10 or 30 minutes) for conditions CAF+PLN (34.3±3.9, 35.4±3.6, and 36.3±3.2 ml/kg/min, respectively) (p=0.07) and NIT+PLC (34.8±3.9, 36.0±4.2, and 36.6±4.4 ml/kg/min, respectively) (p=0.08) compared to PLN+PLC. No difference was observed for heart rate between conditions at any timepoint. However, oxygen-pulse (VO 2 /HR) at the end of exercise was elevated in NIT+CAF (15.1±2.5 ml/beat) compared to CAF+PLN, NIT+PLC, PLN+PLC (14.5±2.5, 14.2±2.5, 13.8±2.5 ml/beat, respectively). Conclusion: When consumed independently, a low-moderate dose of caffeine or dietary nitrate had no impact on oxygen consumption during 30 minutes of moderate intensity exercise. However, co-ingestion of dietary nitrate and caffeine elevated submaximal oxygen consumption compared to a placebo control; both overall (main effect) and at individual time points of 10 and 30 minutes. Additionally, oxygen-pulse was elevated with co-ingestion compared to all treatments perhaps due to enhanced tissue uptake or altered mitochondrial efficiency. Future work may examine such mechanisms.

Running economy and its correlation to performance and fitness variables in recreationally-trained distance runners

Specific physiological attributes such as maximal oxygen consumption (VO2max) and running economy (RE) have been suggested to help predict long distance performance in endurance athletes. Despite this, investigations of RE have yielded conflicting results, particularly when comparing elite and recreational runners. The purpose of this study was to illustrate correlations between RE, expressed as submaximal oxygen consumption at a given speed, and time trial (TT) performance in addition to various fitness markers in endurance-trained individuals. Trained distance runners (n=21) performed a battery of tests over three sessions to provide measurements of RE at 2.68 m/s (RE2.68) and 4.25 m/s (RE4.25), TT performance, VO2max, velocity at ventilatory threshold (VVT), and body composition. Pearson-product moment correlations, defined as weak (r≥0.25), moderate (r≥0.45), and strong (r≥0.65), were calculated among all measures and significance was set at P&lt;0.05. The findings suggested that faster TT performance was significantly (P&lt;0.05) correlated to a higher VO2max (r=-0.86) and lower body fat percentage (BF%; r=0.78). However, TT performance displayed only a weak trend to RE4.25 (r=-0.40, P=0.07) and was not correlated to RE2.68 (r=0.15; P&gt;0.05). Additionally, better RE4.25 (i.e. decreased submaximal oxygen consumption) was associated with a lower VO2max (r=0.66, P&lt;0.05) and an increased BF% (r=-0.46, P&lt;0.05). RE2.68 revealed no significant relationships with these measures. Comparable to their elite counterparts, higher aerobic capacity is strongly linked to performance in recreational distance runners, though in this cohort RE only weakly related to performance at the faster velocity. Finally, the inverse relationship between markers of overall fitness and RE suggests that enhanced RE may be an adaptive response to a limited physiological capacity in this population.

Effects of almond, dried grape and dried cranberry consumption on endurance exercise performance, recovery and psychomotor speed: protocol of a randomised controlled trial

BackgroundFoods rich in nutrients, such as nitrate, nitrite, L-arginine and polyphenols, can promote the synthesis of nitric oxide (NO), which may induce ergogenic effects on endurance exercise performance. Thus, consuming...

Abstract P297: The Decline in Excess Post-Exercise Oxygen Consumption in Response to Dietary Nitrate is Eliminated With Concurrent Caffeine Intake

Introduction: Dietary nitrate has been shown to reduce submaximal oxygen consumption (VO 2 ), but less is known about the changes to excess post-exercise oxygen consumption (EPOC). In contrast, caffeine intake increases both exercise VO 2 and EPOC. Minimal research has reported on the combined effects of dietary nitrate/caffeine on exercise and post-exercise metabolism. Hypothesis: Caffeine will elevate exercise VO 2 and EPOC while dietary nitrate will attenuate the change in exercise VO 2 and EPOC. Methods: Seven healthy individuals participated in a double-blind, placebo controlled, crossover experiment. The first of five visits consisted of a maximal volume of oxygen consumption (VO 2max ) treadmill test. Prior to visit 2 - 5, participants consumed either a dietary nitrate (~12.4 mmol, NIT) or placebo nitrate supplement (PLN) combined with either a caffeine (3 mg/kg, CAF) or placebo caffeine (PLC) dose. Supplements were consumed on each of 4 days and the final doses of NIT or PLN and CAF or PLC were consumed 2.5 and 1-hr pre-exercise, respectively. Visits 2 - 5 consisted of a 30-min treadmill run at ~65% VO 2max followed by a 60-min seated recovery. During exercise, VO 2 and heart rate (HR) were measured continuously. During recovery, EPOC, HR, and peripheral (SBP/DBP) and aortic (cSBP/cDBP) blood pressure (via pulse wave analysis) were measured every 20 min. A linear mixed effects model analysis was performed to determine how each supplementation influenced each dependent variable. Treatments (NIT+CAF, CAF+PLN, NIT+PLC, PLN+PLC) and exercise timepoints (10, 20, 30 min) and recovery timepoints (20, 40, and 60 min post-exercise) served as fixed factors. If p&lt;0.05, p ost-hoc pairwise comparisons were performed. Results: Exercise VO 2 (p=0.450) and HR (p=0.622) were not different between treatments at any timepoint. However, EPOC was different between treatments (p&lt;0.001); NIT+PLC (4.0±0.6 ml/kg/min) was significantly lower than NIT+CAF (4.7±0.7 ml/kg/min, p&lt;0.001), CAF+PLN (4.6±0.7 ml/kg/min p=0.001), and PLN+PLC (4.7±0.8 ml/kg/min, p=0.001). Recovery PLN+PLC brachial SBP (117±8 mmHg) was significantly lower than NIT+CAF (122+7 mmHg, p=0.041), CAF+PLN (123+9 mmHg, p=0.003), and NIT+PLC (122+6 mmHg, p=0.013). Recovery treatment differences were found for cSBP (p=0.005); PLN+PLC (104+7 mmHg) was significantly lower than CAF+PLN (109+9 mmHg, p=0.001), and NIT+PLC (108+7 mmHg, p=0.013), but not NIT+CAF (107+7 mmHg, p=0.063). Recovery HR was elevated in PLN+PLC (91+14 bpm) compared to CAF+PLN (86+15 bpm, p=0.029) and NIT+PLC (86+12 bpm, p=0.002). Conclusion: A modest dose of caffeine (3 mg/kg) did not elevate exercise VO 2 or EPOC. Dietary nitrate reduced EPOC and elevated peripheral and aortic SBP in recovery. When caffeine was consumed alongside nitrate, the decrease in EPOC was abolished. Dietary nitrate alone may not be advised to those seeking additional workout caloric expenditure.

Gross efficiency predicts a 6-min double-poling ergometer performance in recreational cross-country skiers

The purpose of the study was to investigate which physiological parameters would most accurately predict a 6-min, all-out, double-poling (DP) performance in recreational cross-country skiers. Twelve male recreational cross-country skiers performed tests consisting of three series lasting 10 s, one lasting 60 s, plus a 6-min, all-out, DP performance test to estimate mean and peak power output. On a separate day, gross mechanical efficiency (GE) was estimated from a 10-min, submaximal, DP test and maximal oxygen consumption (VO2 max) was estimated from an incremental treadmill running test. Power was measured after each stroke from the acceleration and deceleration of the flywheel that induced the friction on the ergometer. The power was shown to the skier on a small computer placed on the ergometer. A multivariable correlation analysis showed that GE most strongly predicted 6-min DP performance (r = 0.79) and interestingly, neither DP VO2 max, nor treadmill-running VO2 max, correlated with 6-min DP performance. In conclusion, GE correlated most strongly with 6-min DP performance and GE at the ski ergometer was estimated to be 6.4 ± 1.1%. It is suggested that recreational cross-country skiers focus on skiing technique to improve gross mechanical efficiency during intense DP.