Energy Cost Of Exercise Research Articles

Risk of low energy availability and level of nutrition knowledge in recreational trail runners in Aotearoa/New Zealand

Trail running is an endurance sport growing in popularity. It is characterised by long event durations and extreme environments that are likely to result in high exercise energy expenditure. Energy availability is defined as the amount of energy available to support normal physiological functions after subtracting the energy cost of exercise from energy intake. Insufficient energy intake, increased exercise, or a combination of both can result in a state of low energy availability (LEA). While research shows a weak positive association between nutrition knowledge and diet quality, results are conflicting regarding associations between nutrition knowledge and LEA. Research has demonstrated a high prevalence of risk of LEA (~33%-85%) among both elite and recreational athletes, across both sexes and in endurance sports such as running. However, little is known about risk of LEA and nutrition knowledge in trail runners. The aim of this study was to determine the risk of LEA prevalence in recreational trail runners and investigate associations with nutrition knowledge. Risk of LEA was assessed using the ‘Low Energy Availability in Females Questionnaire’ (LEAF-Q)(1), and the ‘Low Energy Availability in Males Questionnaire’ (LEAM-Q)(2). Nutrition knowledge was measured via the ‘Platform for Evaluating Athlete Knowledge in Sports – Nutrition Questionnaire’ (PEAKS-NQ)(3). Demographics and trail-running experience questions were integrated into the survey. Data was analysed in SPSS version 29 (IBM Corporation). Comparisons between groups (e.g. ‘low risk’ vs ‘not low risk’) were performed using a chi-square test for categorical variables, and an independent samples t-test for continuous variables. The final survey sample was 217 (140 females, 42.01 ± 10.72 years; 77 males, 47.86 ± 12.05 years) for the LEAF-Q, LEAM-Q, and trail running questions; and 152 for the PEAKS-NQ. Thirty-one percent of females (n = 43) were classified as ‘not low risk’ of LEA based on the LEAF-Q cut-off of ≥8. Twenty-three percent of males (n = 18) were identified as having low sex drive, a marker of LEA risk. The LEAF-Q/sex drive score was higher in those ‘not at low risk’ (10.72 ± 2.28/4.50 ± 1.95) compared to those at low risk (3.94 ± 2.34/1.53 ± 1.12, p<0.001). Three quarters of general nutrition knowledge responses were correct (females, 78.60 ± 10.09%; males, 75.78 ± 10.67%). However, sports nutrition scores were lower (females, 66.31 ± 13.44%; males, 63.18 ± 15.53%) with the lowest mean scores observed for ‘fuel for during events’. There was no significant association between nutrition knowledge and risk of LEA in both sexes. The findings suggest that recreational trail runners are a group of active individuals who are at risk of LEA and that they might benefit from more sports-specific nutrition education.

Efficiency of cycling exercise: Quantification, mechanisms, and misunderstandings.

The energetics of cycling represents a well-studied area of exercise science, yet there are still many questions that remain. Efficiency, broadly defined as the ratio of energy output to energy input, is one key metric that, despite its importance from both a scientific as well as performance perspective, is commonly misunderstood. There are many factors that may affect cycling efficiency, both intrinsic (e.g., muscle fiber type composition) and extrinsic (e.g., cycling cadence, prior exercise, and training), creating a complex interplay of many components. Due to its relative simplicity, the measurement of oxygen uptake continues to be the most common means of measuring the energy cost of exercise (and thus efficiency); however, it is limited to only a small proportion of the range of outputs humans are capable of, further limiting our understanding of the energetics of high-intensity exercise and any mechanistic bases therein. This review presents evidence that delta efficiency does not represent muscular efficiency and challenges the notion that the slow component of oxygen uptake represents decreasing efficiency. It is noted that gross efficiency increases as intensity of exercise increases in spite of the fact that fast-twitch fibers are recruited to achieve this high power output. Understanding the energetics of high-intensity exercise will require critical evaluation of the available data.

The Impact of Low Energy Availability on Nonexercise Activity Thermogenesis and Physical Activity Behavior in Recreationally Trained Adults.

Energy availability describes the amount of dietary energy remaining for physiological functionality after the energy cost of exercise is deducted. The physiological and hormonal consequences of low energy availability (LEA) are well established, but the impact of LEA on physical activity behavior outside of exercise and, specifically, nonexercise activity thermogenesis (NEAT) has not been systematically examined. The authors conducted a secondary analysis of a repeated-measures crossover study in which recreationally trained young men (n = 6, 25 ± 1.0years) underwent two 4-day conditions of LEA (15kcal·kg fat-free mass-1 ·day-1) with and without endurance exercise (LEA + EX and LEA EX) and two energy-balanced control conditions (CON + EX and CON EX). The duration and intensity of physical activity outside of prescribed exercise were assessed using the SenseWear Pro3 armband. LEA did not alter NEAT (p = .41), nor time spent in moderate to vigorous (p = .20) and low-intensity physical activity (p = .17). However, time spent in low-intensity physical activity was lower in LEA + EX than LEA - EX (13.7 ± 0.3 vs. 15.2 ± 0.3hr/day; p = .002). Short-term LEA does not seem to impact NEAT per se, but the way it is attained may impact physical activity behavior outside of exercise. As the participants expended similar amounts of energy during NEAT (900-1,300kcal/day = 12.5-18.0kcal·kg fat-free mass-1·day-1) and prescribed exercise bouts (15.0kcal·kg fat-free mass-1·day-1), excluding it as a component of energy expenditure may skew the true energy available for physiological functionality in active populations.

A systematic comparison of commonly used stoichiometric equations to estimate fat oxidation during exercise in athletes.

Over the last half-century, different stoichiometric equations for calculating the energy cost of exercise based upon the combustion of mixtures of carbohydrates, fats, and proteins have been proposed and modified. With the means of indirect calorimetry, while measuring oxygen uptake, carbon dioxide production, and urinary urea nitrogen excretion, the contribution of specific substrates to overall energy production can be estimated. However, even with their long history of application, no previous studies have evaluated whether the use of different stoichiometric equations provides similar or distinct maximal fat oxidation rate (MFO) responses and information regarding MFO location (FAT<inf>max</inf>) in male athletes. Twenty healthy male athletes performed graded exercise testing (GXT) cycle ergometry using breath by breath gas analysis to assess fat oxidation and maximal oxygen uptake. Analysis of variance followed by within-equation effects, within-equation factors, and post hoc pairwise comparisons were used to examine within-equation differences. Compared stoichiometric equations demonstrated significant differences in the mean and maximal fat oxidation rates, varying up to nearly 7%. FAT<inf>max</inf> differences, however, were not noticed. Our findings suggest that for within-study designs, the equation used appears to be less important, but when inter-study comparisons are planned, caution is in order due to the presence of inter-equation differences.

Estimating Energy Cost of Body Weight Resistance Exercise Using a Multistage Exercise Test.

Nakagata, T, Yamada, Y, and Naito, H. Estimating energy cost of body weight resistance exercise using a multistage exercise test. J Strength Cond Res 36(5): 1290–1296, 2022—The purpose of this study was to examine energy cost of body weight resistance exercises with slow movement in young men using a multistage exercise test. Fifteen men aged 21–29 years performed 3 exercises (heel-raise, squat, and push-up) at different frequencies (1, 2, 3, 4, 5, and 6 repetitions·min−1). Oxygen consumption was measured using indirect calorimetry; we then computed a simple linear regression between aerobic energy expenditure (EE) and repetition frequency. The slope coefficient in the regression represents the energy cost of those exercises; we compared the extrapolated EE for a frequency of 10 repetitions·min−1. Gross EE increased linearly with repetition frequency in all subjects (y = ax + b). Energy cost was significantly greater in the case of the push-up than in the case of the squat {squat: 0.50 ± 0.14 (95% confidence interval [CI], 0.42–0.58); push-up: 0.77 ± 0.20 kcal (95% CI, 0.66–0.88); and the heel-raise elicited the lowest energy cost: 0.13 ± 0.04 kcal (95% CI, 0.11–0.15)}. Extrapolated EE at 10 repetitions·min−1 was 2.7 ± 0.5 kcal (2.3 metabolic equivalents [METs]), 6.3 ± 1.4 kcal (5.4 METs), and 9.2 ± 2.1 kcal (7.8 METs), respectively, according to the regression based on aerobic EE. These results will be useful for health professionals in prescribing resistance exercise programs improving muscle fitness and considering for weight management.

Comparisons of Resistance Training and "Cardio" Exercise Modalities as Countermeasures to Microgravity-Induced Physical Deconditioning: New Perspectives and Lessons Learned From Terrestrial Studies.

Prolonged periods in microgravity (μG) environments result in deconditioning of numerous physiological systems, particularly muscle at molecular, single fiber, and whole muscle levels. This deconditioning leads to loss of strength and cardiorespiratory fitness. Loading muscle produces mechanical tension with resultant mechanotransduction initiating molecular signaling that stimulates adaptations in muscle. Exercise can reverse deconditioning resultant from phases of detraining, de-loading, or immobilization. On Earth, applications of loading using exercise models are common, as well as in μG settings as countermeasures to deconditioning. The primary modalities include, but are not limited to, aerobic training (or “cardio”) and resistance training, and have historically been dichotomized; the former primarily thought to improve cardiorespiratory fitness, and the latter primarily improving strength and muscle size. However, recent work questions this dichotomy, suggesting adaptations to loading through exercise are affected by intensity of effort independent of modality. Furthermore, similar adaptations may occur where sufficient intensity of effort is used. Traditional countermeasures for μG-induced deconditioning have focused upon engineering-based solutions to enable application of traditional models of exercise. Yet, contemporary developments in understanding of the applications, and subsequent adaptations, to exercise induced muscular loading in terrestrial settings have advanced such in recent years that it may be appropriate to revisit the evidence to inform how exercise can used in μG. With the planned decommissioning of the International Space Station as early as 2024 and future goals of manned moon and Mars missions, efficiency of resources must be prioritized. Engineering-based solutions to apply exercise modalities inevitably present issues relating to devices mass, size, energy use, heat production, and ultimately cost. It is necessary to identify exercise countermeasures to combat deconditioning while limiting these issues. As such, this brief narrative review considers recent developments in our understanding of skeletal muscle adaptation to loading through exercise from studies conducted in terrestrial settings, and their applications in μG environments. We consider the role of intensity of effort, comparisons of exercise modalities, the need for concurrent exercise approaches, and other issues often not considered in terrestrial exercise studies but are of concern in μG environments (i.e., O2 consumption, CO2 production, and energy costs of exercise).

Energy Compensation Following a Supervised Exercise Intervention in Women Living With Overweight/Obesity Is Accompanied by an Early and Sustained Decrease in Non-structured Physical Activity

Background/ObjectivesBody composition (BC) does not always vary as a function of exercise induced energy expenditure (exercise EE – resting EE). Energy balance variables were measured to understand energy compensation (EC) in response to an exercise intervention performed at low (LOW) or moderate (MOD) intensity.Subjects/MethodsTwenty-one women with overweight/obesity (33 ± 5 kg/m2; 29 ± 10 yrs; 31 ± 4 ml O2/kg/min) were randomized to a 3-month LOW or MOD (40 or 60% of VȮ2reserve, respectively) matched to expend 1500 kcal/week (compliance = 97 ± 5%). Body energy stores (DXA), energy intake (EI) (food menu and food diaries), resting EE (indirect calorimetry), total EE (doubly-labeled water), time spent in different activities (accelerometers), appetite (visual analog scale), eating behavior traits and food reward (liking and wanting) were assessed at baseline, after weeks 1 and 2 and at the end of the 3-month exercise intervention.ResultsEC based on BC changes (fat mass and fat-free mass) was 49 ± 79% and 161 ± 88% in LOW and MOD groups, respectively (p = 0.010). EI did not change significantly during the intervention. However, eating behavior traits and food reward had changed by the end of the 3-month supervised exercise. Non-structured physical activity (NSPA) decreased across the intervention (p < 0.002), independent of the intensity of the exercise training.ConclusionWomen with overweight/obesity training at LOW presented lower EC for a given energy cost of exercise. Our results strongly suggest that NSPA plays a major role in mediating the effects of exercise on energy balance and ultimately on changes in BC.Clinical Trial Registrationwww.ClinicalTrials.gov, identifier ISRCTN31641049.

Oxygen Uptake On-Kinetics during Low-Intensity Resistance Exercise: Effect of Exercise Mode and Load.

Oxygen uptake (VO2) kinetics has been analyzed through mathematical modeling of constant work-rate exercise, however, the exponential nature of the VO2 response in resistance exercise is currently unknown. The present work assessed the VO2 on-kinetics during two different sub maximal intensities in the inclined bench press and in the seated leg extension exercise. Twelve males (age: 27.2 ± 4.3 years, height: 177 ± 5 cm, body mass: 79.0 ± 10.6 kg and estimated body fat: 11.4 ± 4.1%) involved in recreational resistance exercise randomly performed 4-min transitions from rest to 12% and 24% of 1 repetition maximum each, of inclined bench press (45°) and leg extension exercises. During all testing, expired gases were collected breath-by-breath with a portable gas analyzer (K4b2, Cosmed, Italy) and VO2 on-kinetics were identified using a multi-exponential mathematical model. Leg extension exercise exhibited a higher R-square, compared with inclined bench press, but no differences were found in-between exercises for the VO2 kinetics parameters. VO2 on-kinetics seems to be more sensitive to muscle related parameters (upper vs. lower body exercise) and less to small load variations in the resistance exercise. The absence of a true slow component indicates that is possible to calculate low-intensity resistance exercise energy cost based solely on VO2 measurements.

Pitfalls of Conducting and Interpreting Estimates of Energy Availability in Free-Living Athletes.

The human body requires energy for numerous functions including, growth, thermogenesis, reproduction, cellular maintenance, and movement. In sports nutrition, energy availability (EA) is defined as the energy available to support these basic physiological functions and good health once the energy cost of exercise is deducted from energy intake (EI), relative to an athlete's fat-free mass (FFM). Low EA provides a unifying theory to link numerous disorders seen in both female and male athletes, described by the syndrome Relative Energy Deficiency in Sport, and related to restricted energy intake, excessive exercise or a combination of both. These outcomes are incurred in different dose-response patterns relative to the reduction in EA below a "healthy" level of ∼45kcal·kg FFM-1·day-1. Although EA estimates are being used to guide and monitor athletic practices, as well as support a diagnosis of Relative Energy Deficiency in Sport, problems associated with the measurement and interpretation of EA in the field should be explored. These include the lack of a universal protocol for the calculation of EA, the resources needed to achieve estimates of each of the components of the equation, and the residual errors in these estimates. The lack of a clear definition of the value for EA that is considered "low" reflects problems around its measurement, as well as differences between individuals and individual components of "normal"/"healthy" function. Finally, further investigation of nutrition and exercise behavior including within- and between-day energy spread and dietary characteristics is warranted since it may directly contribute to low EA or its secondary problems.

Beetroot supplementation improves the physiological responses to incline walking

We investigated the effects of an acute 24-h nitrate-rich beetroot juice supplement (BR) on the energy cost, exercise efficiency and blood pressure responses to intermittent walking at different gradients. In a double-blind, cross-over design, eight participants were provided with a total of 350ml of nitrate-rich (~ 20.5mmol nitrate) BR or placebo (PLA) across 24h before completing intermittent walking at 3km/h on treadmill at gradients of 1, 5, 10, 15 and 20%. Resting mean arterial pressure (MAP) was ~ 4.1% lower after BR (93 vs. 89mmHg; P = 0.001), as well as during exercise (102 vs. 99mmHg; P = 0.011) and recovery (97 vs. 94mmHg; P = 0.001). Exercising (1227 vs. 1129ml/min P < 0.001) and end-stage (1404 vs. 1249ml/min; P = 0.002) oxygen uptake ([Formula: see text]O2) was lower in BR compared to PLA, which was accompanied by an average reduction in phase II [Formula: see text]O2 amplitude (1067 vs. 940ml/min; P = 0.025). Similarly, recovery [Formula: see text]O2 (509 vs. 458ml/min; P = 0.001) was lower in BR. Whole blood potassium concentration increased from pre-post exercise in PLA (4.1 ± 0.3 vs. 4.5 ± 0.3mmol/L; P = 0.013) but not BR (4.1 ± 0.31 vs. 4.3 ± 0.2mmol/L; P = 0.188). Energy cost of exercise, recovery of [Formula: see text]O2, MAP and blood markers were ameliorated after BR. Previously-reported mechanisms explain these findings, which are more noticeable during less-efficient walking at steep gradients (15-20%). These findings have practical implications for hill-walkers.

Acute effects of exercise intensity on subsequent substrate utilisation, appetite, and energy balance in men and women.

Exercise is capable of influencing the regulation of energy balance by acutely modulating appetite and energy intake coupled to effects on substrate utilization. Yet, few studies have examined acute effects of exercise intensity on aspects of both energy intake and energy metabolism, independently of energy cost of exercise. Furthermore, little is known as to the gender differences of these effects. One hour after a standardised breakfast, 40 (19 female), healthy participants (BMI 23.6 ± 3.6 kg·m-2, V̇O2peak 34.4 ± 6.8 mL·kg-1·min-1) undertook either high-intensity intermittent cycling (HIIC) consisting of 8 repeated 60 s bouts of cycling at 95% V̇O2peak or low-intensity continuous cycling (LICC), equivalent to 50% V̇O2peak, matched for energy cost (∼950 kJ) followed by 90 mins of rest, in a randomised crossover design. Throughout each study visit, satiety was assessed subjectively using visual analogue scales alongside blood metabolites and GLP-1. Energy expenditure and substrate utilization were measured over 75 min postexercise via indirect calorimetry. Energy intake was assessed for 48 h postintervention. No differences in appetite, GLP-1, or energy intakes were observed between HIIC and LICC, with or without stratifying for gender. Significant differences in postexercise nonesterified fatty acid concentrations were observed between intensities in both genders, coupled to a significantly lower respiratory exchange ratio following HIIC (P = 0.0028), with a trend towards greater reductions in respiratory exchange ratioin males (P = 0.079). In conclusion, high-intensity exercise, if energy matched, does not lead to greater appetite or energy intake, but may exert additional beneficial metabolic effects that may be more pronounced in males.

Abstract P302: Energy Expenditure Responses to Exercise Training in Older Women: The Influence of Baseline Physical Activity

Introduction: Components of energy expenditure are not static. There is debate over whether there is a reduction in non-exercise activity thermogenesis (NEAT) that compensates for energy cost of exercise training. The purpose of this study was to determine the changes in components of energy expenditure following exercise training, and whether any of the changes differ by dose of exercise. Methods: Older inactive women (60-75 years, less than 20 minutes of structured exercise for 3 times/week, n=72) participated in 4 months of exercise training of lower- or higher-dose (8 and 14 kcal/kg body weight weekly, respectively). The exercise was treadmill walking, 3 to 4 times per week, at 50-55% of heart rate reserve. Total daily energy expenditure (TDEE) by the doubly labeled water method, resting metabolic rate (RMR) via indirect calorimetry, and total physical activity by ActiGraph accelerometers (counts per minute), were measured at baseline and in the last two weeks of exercise training. Exercise energy cost was determined by speed, slope, and duration of walking according to the American College of Sports Medicine guideline. NEAT was calculated as (TDEE x 0.9 – RMR – exercise energy cost). Results: There were no group differences in the changes in energy expenditure measures (p for time x group interaction &gt; 0.10 for all). TDEE, RMR, NEAT and total physical activity did not change at the end of exercise training (p &gt; 0.05 for all). However, a significant baseline physical activity x time interaction was found for several energy expenditure measures. Data were therefore stratified into tertiles based on baseline physical activity. In the highest tertile, TDEE remained unchanged but NEAT and total physical activity decreased (p &lt; 0.05 for all). In contrast, in the mid- and lowest tertiles, NEAT remained unchanged, total physical activity increased, and TDEE was unchanged or increased (p &lt; 0.05 for all). Conclusions: In this group of older women, 4 months of aerobic exercise training did not change any of the energy expenditure measures in the overall sample. However, baseline physical activity levels influenced the energy expenditure responses, indicating reductions in NEAT and total physical activity despite participation in exercise training in those who had higher physical activity level at baseline.

No Effect of Exercise Intensity on Appetite in Highly-Trained Endurance Women.

In endurance-trained men, an acute bout of exercise is shown to suppress post-exercise appetite, yet limited research has examined this response in women. The purpose of this study was to investigate the effect of exercise intensity on appetite and gut hormone responses in endurance-trained women. Highly-trained women (n = 15, 18–40 years, 58.4 ± 6.4 kg, VO2MAX = 55.2 ± 4.3 mL/kg/min) completed isocaloric bouts (500 kcals or 2093 kJ) of moderate-intensity (MIE, 60% VO2MAX) and high-intensity (HIE, 85% VO2MAX) treadmill running at the same time of day, following a similar 48-h diet/exercise period, and at least 1-week apart. Blood was drawn pre-exercise (baseline), immediately post-exercise and every 20-min for the next 60-min. Plasma concentrations of acylated ghrelin, PYY3–36, GLP-1 and subjective appetite ratings via visual analog scale (VAS) were assessed at each time point. Acylated ghrelin decreased (p = 0.014) and PYY3–36 and GLP-1 increased (p = 0.036, p < 0.0001) immediately post-exercise, indicating appetite suppression. VAS ratings of hunger and desire to eat decreased immediately post-exercise (p = 0.0012, p = 0.0031, respectively), also indicating appetite suppression. There were no differences between exercise intensities for appetite hormones or VAS. Similar to males, post-exercise appetite regulatory hormones were altered toward suppression in highly-trained women and independent of energy cost of exercise. Results are important for female athletes striving to optimize nutrition for endurance performance.

Modeling the Total Energy Costs of Resistance Exercise: a Work in Progress

We present an aerobic and anaerobic, exercise and recovery energy cost model of intermittent energy costs utilizing task (work, Joules) as opposed to rate (per minute) measurements. Low to moderate intensity steady state exercise energy costs are typically portrayed as the volumetric rate at which oxygen is consumed (VO2 L min–1), where a proportionate upward climbing linear relationship is profiled with an increasing power output; add to this the concept of the anaerobic threshold and energy costs increase with more intense aerobic exercise in disproportion to VO2 L min–1 measurements. As a per task function, intermittent work and recovery bouts contain a combined estimate of total costs, that is as kJ or kcal (not kJ.min-1 or kcal.min-1). Adopting this approach to describe single and multiple sets of resistance training, the model that emerges for intermittent resistance exercise portrays linearity between equivalent work and total energy costs that differs proportionately among conditions – “continuous” muscular endurance vs. Intermittent higher load strength work, moderately paced vs. slower and faster conditions, smaller vs. larger working muscle masses and failure (fatigue) vs. non-failure states. Moreover, per kcal (or kJ) of total energy costs, work (J) is more inefficient with a greater load and lower repetition number as opposed to lower resistance with an increased number of repetitions. The concept of energy costs Rusing disproportionately with increased or prolonged work does not appear to apply to resistance exercise.

Increasing energy flux to decrease the biological drive toward weight regain after weight loss – A proof-of-concept pilot study

Weight loss induces compensatory biological adjustments that increase hunger and decrease resting metabolic rate (RMR), which increase propensity for weight regain. In non-obese adults high levels of physical activity coupled with high energy intake (high energy flux) are associated with higher RMR and reduced hunger. We tested the possibility that a high flux state attenuates the increase in hunger and the decrease in RMR characteristic of diet-induced weight loss. Six obese adults [age (mean±SE)=42±12y; body mass index (BMI)=35.7±3.7kg/m2] underwent measures of RMR, the thermic effect of a meal (TEM), and fasting and postprandial measures of hunger and fullness as well as plasma glucose and insulin. Following weight loss, subjects completed two 5-day conditions of energy balance in random order-Low Flux (LF): sedentary with energy intake (EI)=RMR (kcal/d)×1.35; and High Flux (HF): net exercise energy cost of ∼500kcal/d and EI=RMR (kcal/d)×1.7. RMR was measured daily for each flux condition. The morning following each of the respective experimentally controlled HF and LF conditions (flux day 5), they underwent the same pre-weight loss tests and also reported their perceptions of hunger and fullness during the previous four days of HF and LF, respectively. Average daily RMR was higher during HF (1926±138kcal/day) compared to LF (1847±126kcal/day; P<0.05). Perceived hunger at the end of day was lower (p<0.03) and fullness throughout the day was higher (p<0.02) in HF compared to LF conditions. On day 5 of each flux condition, the thermic effect of a meal and circulating glucose and insulin after the meal did not differ between HF and LF. Following weight loss, compared to a sedentary LF state of energy balance, a short-term HF energy balance state is associated with higher RMR, lower perceived hunger, and greater perceived fullness, all of which could help attenuate the biologic drive to regain weight. Given the pilot nature of this study and the relatively short period of time spent in the high and low flux states, future research is needed to address this research question in a larger sample over a longer time period.

Resistance Exercise Attenuates High-Fructose, High-Fat-Induced Postprandial Lipemia.

INTRODUCTIONMeals rich in both fructose and fat are commonly consumed by many Americans, especially young men, which can produce a significant postprandial lipemic response. Increasing evidence suggests that aerobic exercise can attenuate the postprandial increase in plasma triacylglycerols (TAGs) in response to a high-fat or a high-fructose meal. However, it is unknown if resistance exercise can dampen the postprandial lipemic response to a meal rich in both fructose and fat.METHODSEight apparently healthy men (Mean ± SEM; age = 27 ± 2 years) participated in a crossover study to examine the effects of acute resistance exercise on next-day postprandial lipemia resulting from a high-fructose, high-fat meal. Participants completed three separate two-day conditions in a random order: (1) EX-COMP: a full-body weightlifting workout with the provision of additional kilocalories to compensate for the estimated net energy cost of exercise on day 1, followed by the consumption of a high-fructose, high-fat liquid test meal the next morning (day 2) (~600 kcal) and the determination of the plasma glucose, lactate, insulin, and TAG responses during a six-hour postprandial period; (2) EX-DEF: same condition as EX-COMP but without exercise energy compensation on day 1; and (3) CON: no exercise control.RESULTSThe six-hour postprandial plasma insulin and lactate responses did not differ between conditions. However, the postprandial plasma TAG concentrations were 16.5% and 24.4% lower for EX-COMP (551.0 ± 80.5 mg/dL × 360 minutes) and EX-DEF (499.4 ± 73.5 mg/dL × 360 minutes), respectively, compared to CON (660.2 ± 95.0 mg/dL × 360 minutes) (P < 0.05).CONCLUSIONSA single resistance exercise bout, performed ~15 hours prior to a high-fructose, high-fat meal, attenuated the postprandial TAG response, as compared to a no-exercise control condition, in healthy, resistance-trained men.

Changes in energy cost and total external work of muscles in elite race walkers walking at different speeds.

The aim of the study was to assess energy cost and total external work (total energy) depending on the speed of race walking. Another objective was to determine the contribution of external work to total energy cost of walking at technical, threshold and racing speed in elite competitive race walkers.The study involved 12 competitive race walkers aged 24.9 4.10 years with 6 to 20 years of experience, who achieved a national or international sports level. Their aerobic endurance was determined by means of a direct method involving an incremental exercise test on the treadmill.The participants performed three tests walking each time with one of the three speeds according to the same protocol: an 8-minute walk with at steady speed was followed by a recovery phase until the oxygen debt was repaid. To measure exercise energy cost, an indirect method based on the volume of oxygen uptake was employed. The gait of the participants was recorded using the 3D Vicon opto-electronic motion capture system.Values of changes in potential energy and total kinetic energy in a gate cycle were determined based on vertical displacements of the centre of mass. Changes in mechanical energy amounted to the value of total external work of muscles needed to accelerate and lift the centre of mass during a normalised gait cycle.The values of average energy cost and of total external work standardised to body mass and distance covered calculated for technical speed, threshold and racing speeds turned out to be statistically significant (p 0.001).The total energy cost ranged from 51.2 kJ.m-1 during walking at technical speed to 78.3 kJ.m-1 during walking at a racing speed. Regardless of the type of speed, the total external work of muscles accounted for around 25% of total energy cost in race walking. Total external work mainly increased because of changes in the resultant kinetic energy of the centre of mass movement.

Creating an acute energy deficit without stimulating compensatory increases in appetite: is there an optimal exercise protocol?

Recent years have witnessed significant interest from both the scientific community and the media regarding the influence of exercise on subsequent appetite and energy intake responses. This review demonstrates a consensus among the majority of scientific investigations that an acute bout of land-based endurance exercise does not stimulate any compensatory increases in appetite and energy intake on the day of exercise. Alternatively, preliminary evidence suggests that low volume, supramaximal exercise may stimulate an increase in appetite perceptions during the subsequent hours. In accordance with the apparent insensitivity of energy intake to exercise in the short term, the daily energy balance response to exercise appears to be primarily determined by the energy cost of exercise. This finding supports the conclusions of recent training studies that the energy expenditure of exercise is the strongest predictor of fat loss during an exercise programme.

Matching energy intake to expenditure of isocaloric exercise at high- and moderate-intensities

BackgroundThose seeking to manage their bodyweight use a variety of strategies, but the most common approaches involve attempting to exercise more and/or consume fewer calories. A poor comprehension of the energy cost of exercise and the energy content of food may contribute to weight-gain and the poor success rate of exercise weight-loss interventions. PurposeThe purpose of this study is to investigate individuals' ability to consciously match energy intake with energy expenditure after isocaloric exercise at moderate and high intensities. MethodIn a counterbalanced cross-over study design, 14 low- to moderately-active, lean individuals (7 male, 7 female; mean age 23±3years; mean BMI 22.0±3.2kg·m−2) completed both a moderate-intensity (60% VO2max, MOD) and a high-intensity (90% VO2max, HIGH) exercise bout on a treadmill, matched for energy expenditure, EE (450kcal). Participants were blinded to the intensity and duration of each bout. Thirty minutes post-exercise, participants were presented with a buffet, where they were asked to consume food in an attempt to match energy intake with the energy expended during the exercise bout. This was termed the “matching task,” providing a matching task energy intake value (EIMATCH). Upon finishing the matching task, a verbal estimate of energy expenditure (EST) was obtained before the participant was allowed to return to the buffet to consume any more food, if desired. This intake was covertly measured and added to EIMATCH to obtain an ad libitum intake value (EIAD LIB). ResultsA significant condition×task interaction showed that, in MOD, EST was significantly lower than EE (298±156kcal vs. 443±22kcal, p=0.01). In the HIGH condition, EE, EIMATCH and EST were similar. In both conditions, participants tended to over-eat to a similar degree, relative to EST, with EIMATCH 20% and 22% greater than EST in MOD and HIGH respectively. Between-condition comparisons demonstrated that EIMATCH and EST were significantly lower in MOD, compared with HIGH (374±220kcal vs. 530±248kcal, p=0.002 and 298±156kcal vs. 431±129kcal, p=0.002 respectively). For both conditions, EIAD LIB was approximately 2-fold greater than EE. DiscussionParticipants exhibited a strong ability to estimate exercise energy expenditure after high-intensity exercise. Participants appeared to perceive moderate-intensity exercise to be less energetic than an isocaloric bout of high-intensity exercise. This may have implications for exercise recommendations for weight-loss strategies, especially when casual approaches to exercise and attempting to eat less are being implemented.

B-12 短時間歩行における酸素摂取量推定法(サイクリング2ほか)

Amount of daily physical activity is strongly associated with the prevalence of lifestyle-associated diseases, and thus maintaining a certain level of physical activity is recommended. Amount of physical activity, namely energy expenditure, is commonly estimated from linear regression analysis of oxygen uptake during steady-state exercise of different intensities. Short-duration exercise, mainly walking lasting less than 3 minutes, has been reported to account for over 90% of the daily energy expenditure of healthy adults. In a rodent study that measured the oxygen consumption of rodents running for different durations, the energy cost of exercise was shown to decrease as exercise duration increased, so that the oxygen consumption level asymptotically converged at a steady-state level. Wearable accelerometer-based activity counters have widely been used for physical activity assessment. The estimation of energy expenditure by these devices, however, is based on steady-state exercise of more than 5 minutes, and energy consumption of shorter duration exercise is not commonly considered. Oxygen consumption remains elevated for some period of time after exercise. Then, the estimation of energy expenditure for short duration exercise must include excess post-exercise oxygen consumption (EPOC). The amount of EPOC change in duration exercise. Therefore, we attempted to elucidate the energy expenditure for VO_2 kinetics. Healthy men (age 20-40) walked for 1, 3 and 5 minutes on a treadmill at constant speed. Oxygen consumption during and post-exercise was measured using a portable gas analyzer in breath-by-breath mode. A best-fit exponential equation to estimate oxygen consumption from exercise duration and walking speed was generated. The measured data of 3 subjects not used in generating the formula were assessed for systematic error. Cross-validation of estimated oxygen consumption revealed 3.86(ml/kg/min) RMS, and the results of the Bland-Altman analysis revealed neither fixed nor proportional bias. An equation for the estimation of energy expenditure at shorter durations of exercise was successfully generated. Accumulation of additional data may further improve the equation.