Exercise Energy Expenditure Research Articles

Compartmentalised disciplines: Why low energy availability research calls for transdisciplinary approaches

Low energy availability (LEA) occurs when dietary intake does not meet the demands of normal physiological functioning once exercise energy expenditure is accounted for. LEA is the underlying aetiology of relative energy deficiency in sport (RED-S). Research that investigates the effects of LEA typically falls into two categories: physiological and socio-psychological. Each category rightly has their place in the literature and have contributed to the singular aspects of RED-S research. However, as RED-S is incredibly complex and integrated there is a need for transdisciplinary research to fully understand the complexities of this syndrome in athletes. This paper will briefly look at the current literature as separate disciplines to highlight the need for a novel approach of using transdisciplinary methods in athletic populations.

Metabolic Demands, Center of Mass Movement and Fractional Utilization of in Elite Adolescent Tennis Players During On-Court Drills.

The aim of the study was to investigate the exercise intensity and energy expenditure during four types of on-court tennis drills. Five female and five male tennis players participated in the study (age: 17 ± 2 years; : 54 ± 6 ml·kg−1·min−1). Anthropometric measures were taken for each player and, on separate days, each player performed (i) treadmill running to determine and (ii) four different tennis drills (Drill1-4) during which , blood lactate concentration, ratings of perceived exertion (RPE 6–20), and displacement of center of mass (m) using 3D kinematics were recorded. The drills were designed to simulate match play with 90 s of rest between each drill. A repeated two-way ANOVA was used for physiological and biomechanical data and Friedman's test for RPE using < α 0.05. Fractional utilization of was greatest during Drill1 81.8 ± 7.0% and lowest during Drill4 72.4 ± 5.2% (p < 0.001) with no difference between sexes (p > 0.05). The highest energy expenditure was during Drill1 and lowest during Drill4 (77 ± 15 and 49 ± 11 kcal, respectively, p < 0.05). Energy expenditure per meter for Drill1–Drill4 was subsequently reduced for each drill with 10.5 ± 2.1, 9.9 ± 2.2, 7.6 ± 1.7, and 8.0 ± 1.6 J·kg−1·m−1 (p < 0.01). There were no interaction effects for any of these variables. RPE (6–20) and blood lactate concentration post Drill1–Drill4 were 17.5, 15.5, and 13.0 (overall, legs and arms, p < 0.001) and 5.9 ± 2.0, 4.9 ± 1.9, 5.6 ± 2.0, and 5.0 ± 2.2 mmol·l−1 (p < 0.05). The findings of this study demonstrate that the on-court tennis drills performed here are suitable for high intensity training in junior tennis players. The energy expenditure per minute is comparable to similar sports whereas the energy expenditure per meter is notably greater.

Examination Of Energy Needs Across 2-week High-Intense Functional Exercise Program In Recreational Athletes

Increases in physical activity without proper nutritional knowledge may expose recreational athletes to compromised energy needs and macronutrient profiles. PURPOSE: To examine the energy needs across a 2-week high intense functional exercise program in female and male recreational athletes. METHODS: Thirty adults (age: 31.2 ± 8.1; females: 164.7 ± 7.1 cm, 69.9 ± 11.1 kg; body fat%: 29.2 ± 5.5%; males: n=12, 176.9 ± 6.2 cm, 89.5 ± 15.1 kg, body fat%: 22.3 ± 8.8%) participated in a larger cross-sectional study. Participants completed a demographic survey, a 7 day online dietary and exercise log across 2 weeks. Measurements included; height, weight, and DXA scan (body fat%) at the beginning of the study. Exercise energy expenditure (EEE) was calculated using Ainsworth/Heyward equations, energy availability (EA) was calculated by EA = ((EI - EEE)/FFM.kg-1) and energy balance (EB) was calculated by EB = (EI – TDEE = 0). Macronutrients (CHO, PRO, and fats) were assessed using ACSM recommendations (recs.). Low EA (LEA) was defined at >30 kcals/FFM.kg-1 and EB was defined as negative, balanced, or positive, and Macros were defined as low, within or above recs. RESULTS: Results yielded LEA (week 1: 73.3%, n = 22, week 2: 80% n=24) and negative EB (week 1: 94.4%, n=17; 75.0%, n=9) across the two weeks. No significant differences were found between gender or training weeks for energy needs and Macros. Over the 2 weeks, participants demonstrated similar energy needs including: EI (week 1: 1752.3 ± 599.8 kcals, week 2: 1831.2 ± 634.4 kcals), EEE (week 1: 310.7 ± 63.7 kcals, week 2:302.7 ± 62.1 kcals), EA: (week 1: 25 ± 10.1 kcals/FFM.kg-1, week 2: 25.1 ± 9.8 kcals/FFM.kg-1), TDEE (week 1: 2518.5 ± 266.1 kcals, week 2: 2543.1 ± 286.1 kcals), and EB (week 1: -766.2 ± 627.4 kcals, week 2: -712 ± 652.3 kcals). Macronutrients were also similar between weeks; with PRO intake within recommendations (week 1: 50%, n=15; week 2: 63%, n=17, n=6), CHO intake was extremely low (week 1: 96.7%, n=29; week 2: 93.3%, n=28,) and fats were within recs. (week 1: 62.1%, n=18; week 2: 46.7%, n=9). CONCLUSION: Participants demonstrated consistent EI and EEE habits over the 2 weeks, however, the recreational athletes under consumed CHO and presented at risk for LEA and negative EB. This leads to compromised fueling for the EEE utilized during training. Funded by Avadim Technology

IMPACT OF CASEIN PROTEIN CONTAINING L-TRYPTOPHAN AND MELATONIN ON SLEEP QUALITY AND ENERGY EXPENDITURE

Increases in morning resting energy expenditure (REE) have been observed following late evening ingestion of protein. However, the impact of late night protein supplementation containing melatonin and L-Tryptophan has yet to be examined. PURPOSE: The purpose of this study is to determine the impact of the ingestion of pre-sleep casein protein supplement that contains L-Tryptophan and melatonin (PRO) on sleep quality, energy expenditure prior, during, and post exercise. METHODS: Aerobically active females (n = 13; age = 22.6 ± 1.9 yrs; ht = 1.65 ± 0.06 m; wt = 60.5 ± 9.6 kg; % bf = 22.5 ± 4.3; VO2max = 44.1 ± 5.3 ml/kg/min) participated in the study. In a cross-over design, PRO (Casein; 34.3g; 140 kcal; 289mg L-Tryptophan; 1mg Melatonin) or placebo (PLA) (cocoa powder; 10g; 20 kcal) were ingested 30 min prior to sleep. Sleep quality and perceived satiety were assessed using 10cm sliding scale the following morning. REE was measured for 30 minutes with at least 5 min of steady state before and after exercise. The exercise protocol consisted of 20 min of aerobic exercise on a treadmill at 40-50% of VO2max. Total calories during exercise were used to compare exercise energy expenditure (EEE). For the statistical analyses, Paired-samples t-tests and two-way repeated measures ANOVA. Results were considered significant at ≤ 0.05. RESULTS: Sleep quality during PRO was not significantly different than the PLA trial (61.6 ± 21.5 mm vs 68.4 ± 20.5 mm; p = 0.39). Perceived satiety during PRO was not significantly different than PLA (29.6 ± 8.2 mm vs 23.9 ± 6.6 mm; p = 0.43). EEE during PRO was not significantly different than PLA (112.1 ± 20.4 kcals vs 112.2 ± 21.8 kcals; p = 0.91). The main effects (supplement: p = 0.93; time: p = 0.15) and the interaction (Supplement x Time: p = 0.75) for REE pre and post exercise in PRO and PLA were not significantly different. CONCLUSIONS: No changes were observed ingesting PRO prior to sleep on next morning EEE and REE before and after exercise. Future investigations should examine the effects of relative (g/kg bw) pre-sleep protein containing tryptophan and melatonin ingestion on next morning EEE.

The Relationship Between Changes In Sleep, Inflammatory Biomarkers, And Energy Expenditure In Female Soccer Players

The chronic stress of training and frequent travel during the competitive soccer season may adversely affect sleep and thus, recovery in collegiate athletes. PURPOSE: To examine the relationship between changes in sleep, inflammatory biomarkers, and exercise energy expenditure (EEE) throughout the season. METHODS: DI female soccer players (N=24) were monitored throughout the competitive season. During all training and games, EEE (kcal/kg) was evaluated using an integrative GPS and heart rate monitoring system, which was individualized based on pre-season performance testing. Pittsburgh Sleep Quality Index (PSQI) questionnaires, weight assessments, and blood draws were completed prior to preseason and at weeks 2, 4, 8, & 12 of the season. Total cortisol (TCORT), free cortisol (FCORT), c-reactive protein (CRP), IL-6, and TNFα were analyzed. Change scores were calculated between timepoints for each biomarker, GlobalPSQI, Sleep Duration (SD), and Sleep Quality (SQ) scores. Pearson product correlations were conducted between change scores as well as EEEAVG between timepoints with significance set at p<.05. RESULTS: ΔGlobalPSQI was not related to any measures, except ΔSD and ΔSQ (r=.39, r=.51; p<.05). ΔSD and ΔSQ were both significantly correlated to ΔIL-6 (r=-.21, r=-.23; p<.05). ΔIL-6 was positively correlated to ΔCRP (r=.32, p<.05), ΔTNFα (r=.43, p<.05), and ΔFCORT (r=.26, p<.05). ΔCRP was also significantly related to ΔTCORT (r=.24, p<.05). EEEAVG was not associated with any measures (p>.05). CONCLUSIONS: There appears to be a relationship, albeit weak, between sleep measures and IL-6, with increased SD and SQ (i.e. decreased PSQI score) related to increases in IL-6. Additionally, increased IL-6 was associated with increases in other proinflammatory and stress markers, potentially indicative of fuel mobilization and physiological repair responses. The cumulative load of the competitive season could indicate an increased need for recovery, thus yielding compensatory increases in SD and perceived SQ. Further research is warranted using objective sleep measures to examine the observed relationship in soccer players. Funding provided by Quest Diagnostics

A Nutritional Intervention In Exercising Women With Oligo/Amenorrhea Improved Energy Availability

Reduced energy availability (EA) suppresses reproduction and induces oligo/amenorrhea (O/A) in exercising women. Treatment goals are to increase energy intake (EI) to improve EA and restore menstrual function. PURPOSE: Determine if a nutritional intervention that increased EI in exercising women with O/A improved EA and energetic status. METHODS A 12 month randomized controlled trial designed to increase energy intake 20-30% above baseline energy needs in exercising women with O/A randomized participants into O/A+CAL (n=13) and Control (n=10) groups. EI and exercise energy expenditure (EEE) were assessed throughout the intervention. EA was calculated as EI-EEE/fat free mass (FFM). Fasting blood samples were collected to assess TT3 and leptin. Independent t-tests/Mann-Whitney U tests compared differences between groups and correlations were run between changes in energy and hormones. Data are mean ± SE. RESULTS Subjects were 22±1 yr, BMI 20.0±0.4 kg/m2. Menstrual recovery was observed and previously reported. There were no pre intervention differences in EI (1837±95 kcal/d), EEE (390±40 kcal/d), FFM (41.5±0.8 kg) or EA (37.2±2.7 kcal/kg FFM/d) between groups. During the intervention there were greater absolute and percent increases in EI in O/A+CAL vs Control (448±170 vs -117±147 kcal/d, p=0.02; 23.6±8.6 vs -4.6±8.4%, p=0.03). There were no differences between groups in absolute or percent change for EEE (133±46 kcal/d, p=0.07; 38.8±11.3%, p=0.10) or FFM (0.6±0.3kg, p=0.60; 1.6±0.7%, p=0.51). Absolute increase in EA was greater in O/A+CAL vs Control (10.8±5.5 vs -6.0±3.9 kcal/kg FFM/d, p=0.03), but no difference in percent change (29.2±13.4 vs -6.7±12.5%; p=0.07). Absolute and percent increase in fat mass (2.3±0.3 vs 0.7±0.5, p<0.01; 20.6±3.1 vs 5.4±3.2%, p<0.01) and body mass (3.2±0.3 vs 0.8±0.8, p<0.01; 6.1±0.7 vs 1.5±1.3%, p<0.01) were greater in O/A+CAL vs Control. O/A+CAL had larger absolute and percent increases in TT3 (10.3±5.0 vs -6.7±5.3 ng/dL, p=0.03; 17.2±7.4 vs -8.3±5.5%, p=0.02) and percent increase in leptin (85.1±24.0 vs -13.3±18.0%) vs Control. Changes in EI and EA were not associated with changes in hormonal markers. CONCLUSION An intervention designed to improve EI can be considered an effective nutritional intervention for managing oligo/amenorrhea in exercising women.

The Effects Of High Intensity Interval Training Versus Moderate Intensity Continuous Training On Energy Compensation

To determine the effects of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on energy compensation in response to 12-weeks of supervised aerobic exercise. After a 4 wk lead in period of 3x/wk of MICT, subjects (N = 24) were randomly assigned into: HIIT or MICT, for an additional 8 wks. HIIT included a 10x1 min protocol 3x/wk and MICT included 30 min of exercise 5x/wk. Subjects completed both stationary cycling and inclined treadmill exercise. 13 participants (1 M, 12 F) were randomized into the HIIT group (28.0 ± 9.7 yr; BMI = 23.9 ± 3.9 kg/m2; VO2max = 29.0 ± 6.0 ml/kg/min). 11 participants (2 M, 9 F) were randomized into the MICT group (26.0 ± 6.9 yr; BMI = 27.4 ± 8.7 kg/m2; VO2max = 26.2 ± 7.3 ml/kg/min). Resting metabolic rate (RMR), body composition, and maximal oxygen uptake (VO2max) were measured at baseline and after 4 and 12 wks. Physical activity and dietary intake were measured for 7-day periods pre-intervention and during wks 5 and 12. Compensation was calculated through caloric equivalents of fat and lean mass compared to cumulative total exercise energy expenditure. 5 of 11 in MICT and 6 of 13 in HIIT were categorized as compensators. Change in fat mass (kg) (MICT: -0.59 ± 1.89, HIIT: -0.03 ± 1.72, p=0.45), change in weight (kg) (MICT: +0.66 ± 2.11, HIIT: -0.54 ± 1.45, p=0.12), and overall compensation (kcal) (MICT: 3111 ± 17220, HIIT: 3870 ± 15911, p=0.91) were similar between exercise groups. The difference between actual and predicted weight loss was greater for MICT (-1.61 ± 2.15 kg) than HIIT (-0.07 ± 1.45 kg, p=0.049). Potential compensatory variables including changes in RMR, VO2max, daily steps, and sedentary time were not different between the compensator and non-compensator groups (P > 0.05). Mean energy and macronutrient intake did not differ among all participants, by exercise intervention group, or by compensation status (P > 0.05). Both HIIT and MICT led to a similar percentage (~45%) of participants compensating for the exercise intervention. Despite the large difference in cumulative exercise training time (480 vs 1200 min, HIIT vs MICT), body fat and weight changes were similar between groups. Finally, our data suggests that HIIT may elicit weight loss that is closer to that predicted by exercise energy expenditure when compared to MICT.

Examination Of Low Energy Availability (LEA) And Macronutrient Intake Among Beach Volleyball Players

Low energy availability (LEA) may be prevalent in female collegiate beach volleyball players, which can be a catalyst for negative health consequences. Athletes can present in a state of LEA as a result of inadequate intake of the recommended macronutrients; those being proteins (PRO), carbohydrates (CHO), and fats. PURPOSE: Examine the prevalence of LEA and macronutrient intakes (PRO, CHO, and fats) among NCAA Division I female collegiate beach volleyball players. METHODS: Data from a larger cross-sectional study was used to examine recreational athletes (n=18; age: 19.8±1.4 years; height: 174.4±5.5 cm; weight: 63.2±5.1 kg). Athletes were moderately trained (exercised a minimum of 3-4 days/week). Data collection consisted of anthropometric data, surveys (e.g., demographics, age, gender, etc.), resting metabolic rate (RMR), a 7-day online dietary log to measure energy intake (EI), and exercise logs to measure exercise energy expenditure (EEE). Basic descriptive statistics, Chi-squares, and cross-tabulations were used to examine the proportion of participants classified as “at risk” for LEA (<30 kcal/kg/FFM) and the proportion that met the macronutrient recommendations. RESULTS: Overall, beach volleyball players demonstrated the following, with 94.4% (n=17) being identified as at risk for LEA: Average energy availability (EA): 12.4±9.6 kcal/kg FFM and average EEE: 1108.7±157.6 kcals. RMR recommendations for average minimal caloric intake for the sample was 1477.7±272.3 kcals; however, 55.6% (n=10) did not meet the recommendations. Recommended CHO and PRO macronutrient intake were not met by 100% and 61.1% of the sample, respectively. Overconsumption of fat compared to the recommendation was found in 33.3%. CONCLUSIONS: Beach volleyball athletes in this sample were severely and alarmingly at risk for LEA. Most of the athletes demonstrated low CHO and PRO intake while overconsuming fat compared to the recommendations. These athletes would benefit from nutrition education focused on properly fueling and macronutrient intake, which are both essential for elite performance in the athletic arena.

Examination Of Energy Availability And Hydration Status Among University Marching Band Artists

Marching band (MB) members rehearse for pre-game and half-time performances outdoors for several hours a day starting at the end of July or beginning of August. There is lack of research on energy needs (e.g., energy availability) and proper hydration in MB during these hot months. PURPOSE: To examine energy availability and hydration status among MB members. A secondary purpose was to examine differences between sex. METHODS: We utilized data from a larger cross-sectional study. MB artists (n=37, Males: n=12, age: 19.8±1.4 years, height: 177.1±7.8 cm, weight: 74.6±23.8 kg; Females: n=25, age: 20.0±1.1 years, weight: 68.4±16.4 kg; height: 163.3±4.6 cm) from an NCAA Division I institution completed a survey (eg, basic demographics, band background, etc.) and were measured for height, weight, body composition, and resting metabolic rate (RMR). For 7-days, participants completed an online dietary log to measure energy intake (EI), wore a Polar m200 watch to estimate exercise energy expenditure (EEE) during rehearsals and gameday performances, and provided a morning urine sample to measure urine specific gravity (Usg). Low energy availability (LEA) was defined as <30 kcal/kg FFM/day and hypohydration was Usg >1.025. Basic descriptive statistics examined all energy needs and Usg. Chi square were used to identify proportions of members “at risk” for LEA and hypohydration and compared the differences across sex. RESULTS: Significant differences were found for EI for males and females respectively (2090.2±676.7 kcal, 1531.0± 460.8 kcals, P=.002)). No significant differences were found for EEE and EA for males and females (335.5±66.0 kcal, 333.8± 66.9 kcals and 23.6±11.0 kcal/kg FFM, 22.9± 10.1 kcal/kg FFM). Overall, 73.7% (n=28) were at risk for LEA. No significant differences were found for Usg and sex (Males: 1.022±.006, Females: 1.022±.005), however 36.8% (n=14) reported chronically hypohydrated (> 4/7 days >1.025). Of those with LEA (n=28), 31.6% (n=12) also reported to be chronically hypohydrated. CONCLUSION: The majority of MB members had LEA and over a third were also chronically hypohydrated. Due to performances in hot and humid environments, as well as the physical demands associated with MB, healthcare professionals should provide resources and education on hydration and proper fueling for MB artists.

The Impact Of Exercise Energy Expenditure On Total Daily Energy Expenditure.

The Impact Of Exercise Energy Expenditure On Total Daily Energy Expenditure.

Validity And Reliability Of Small Respiratory Chamber To Assess Exercise Energy Expenditure

The recently created small respiratory chambers (FLEX rooms) permit a more affordable solution and faster response time than the larger traditional whole room respiratory chambers. Despite the potential for FLEX to employed to assess acute energy expenditure (EE), it has never been validated for submaximal exercise. PURPOSE: To perform concurrent validation and reliability analysis of indirect calorimetry of FLEX against metabolic carts (Cart) during submaximal cycling. METHODS: Ten healthy participants were included in this study (41.5±15.2 years; BMI=25.8±3.3 kg/m2). Energy expenditure was evaluated on FLEX and mixing chamber Cart, simultaneously. FLEX is an 11,000-liter room operated by a push-pull system and mass flow controllers. Participants performed two submaximal exercise bouts of 30-minutes the same day with a 30-minute resting period between bouts, each bout had a light and a moderate load; they repeated the same protocol after two days. Oxygen uptake (VO2) and CO2 production (VCO2) were derived with the same equation. EE, Net EE, gross efficiency (GE) and net efficiency (NetEF) were calculated for each load (L1 & L2). FLEX within and between-day reliability was calculated by the standard deviation of the differences in kcal/min and %. Repeated measures analysis was utilized to explore differences between Cart and FLEX. RESULTS: EE and NetEE were not significantly different between cart and FLEX technologies (EEL1, FLEX= 4.29 vs. Cart= 4.13 kcal/min, EEL2, FLEX= 6.2 vs. Cart=6.0 kcal/min, P>0.05 for both; NetEEL1, FLEX= 2.7 vs. Cart=2.7 kcal/min, EEL2, FLEX= 4.63 vs. Cart=4.57 kcal/min, P>0.05 for both). GE and NetEF were similar between both systems for all loads (GEL1, FLEX= 11.8% vs. Cart= 12.3%, GEL2, FLEX= 16.3% vs. Cart= 18.9%, P>0.05 for both; NetEFL1, FLEX= 18.8% vs. Cart=18.9%, NetEFL2, FLEX= 22.0% vs. Cart= 22.4%, P>0.05 for both). FLEX assessments of EE were highly reliable within-day (L1= 0.11 kcal/min (2.5%) and L2= 0.07 kcal/min (1.1%)) and between-days (L1= 0.10 kcal/min (2.4%) and L2= 0.14 kcal/min (2.2%)). CONCLUSION: FLEX is a valid and reliable technique to assess energy metabolism during exercise without the cumbersome mouthpiece or mask required by metabolic carts.

Perspectives on Exercise Intensity, Volume and Energy Expenditure in Habitual Cycle Commuting.

Background: Knowledge about exercise intensity and energy expenditure combined with trip frequency and duration is necessary for interpreting the character and potential influencing capacity of habitual cycle commuting on e.g., health outcomes. It needs to be investigated with validated methods, which is the purpose of this study.Methods: Ten male and 10 female middle-aged habitual commuter cyclists were studied at rest and with maximal exercise tests on a cycle ergometer and a treadmill in the laboratory. During their normal commute in the Stockholm County, Sweden, their oxygen uptake, heart rate, energy expenditure, ventilation, blood lactate, rated perceived exertion, number of stops, durations, route distances and cycling velocities were monitored with validated methods. The frequency of trips was self-reported.Results: The relative exercise intensity was 65% of maximal oxygen uptake, and the energy expenditure was 0.46 kcal per km and kg body weight for both sexes. Sex differences in MET-values (men, 8.7; women 7.4) mirrored higher levels of cycling speed (20%), body weight (29%), oxygen uptake (54%) and ventilation (51%) in men compared to women. The number of METhours per week during peak cycling season averaged 40 for the men and 28 for the women. It corresponded to a total energy expenditure of about 3,500 and 1,880 kcal for men and women, respectively. The number of trips per year was about 370, and the annual distance cycled was on average 3,500 km for men and 2,300 for women.Conclusion: Cycle commuting is characterized by equal relative aerobic intensity levels and energy requirements for a given distance cycled by men and women. Based on an overall evaluation, it represents a lower range within the vigorous intensity category. The combined levels of oxygen uptake, durations and trip frequencies lead to high levels of METhours and energy expenditure in both men and women during both peak cycling season as well as over the year. Overall, the study presents a novel basis for interpreting cycle commuting in relation to various health outcomes.

Exercise and Testosterone Countermeasures to Mitigate Metabolic Changes during Bed Rest

Background/Objectives: Exercise is a front-line countermeasure used to maintain astronaut health during long-duration spaceflight; however, reductions in metabolic health still occur. Accordingly, we evaluated serial changes in metabolic parameters in a spaceflight analog and evaluated the efficacy of exercise with or without the addition of low-dose testosterone treatment on mitigating adverse metabolic changes. Subjects/Methods: Healthy young (<55 years) men were randomly assigned to one of three groups during 70-days of strict, diet controlled, 6° head-down bed rest: Control (CON, n=9), exercise plus testosterone countermeasure (TEX, n=8), or exercise countermeasure plus placebo (PEX, n=9). Basal metabolic rate (BMR), glucose tolerance, and insulin sensitivity were measured before, during, and after bed rest. Exercise energy expenditure and excess post-exercise oxygen consumption were measured in TEX and PEX subjects during bed rest. Results: Leptin decreased during bed rest (Pre to BR+0 changed from 6.9 ± 5.1, 5.8 ± 4.2, and 4.7 ± 4.1 to 7.9 ±3.6, 6.5 ± 4.6, and 4.1 ±3.0 ug• L−1 for CON, PEX, and TEX respectively). Bed rest induced a decrease in BMR (Pre to BR57 changed from 1655 ± 212, 1629 ± 108, and 1706 ± 146 to 1476 ± 166, 1668 ± 142, and 1603 ± 132 kcal • day−1 ± 95%CI for CON, PEX, and TEX respectively). Similarly, bed rest negatively affected glucose metabolism assessed by 2hr OGTT glucose (Pre to BR66 changed from 6.29 ± 0.72, 5.13 ± 0.72, and 5.87 ± 0.73 to 6.62 ± 0.72, 5.83 ± 0.72, and 7.08 ± 0.72 mmol • L−1 ± 95%CI). Reambulation following bed rest positively affected glucose tolerance in CON (2hr OGTT glucose at BR+12: 5.3 ± 0.72, 6.42 ± 0.73, and 6.04 ± 0.73 mmol • L−1 ± 95%CI). Testosterone protected against bed rest induced insulin resistance (HOMA-IR from Pre to BR+66 changed from 1.74 ± 0.54, 1.18 ± 0.55, and 1.45 ± 0.56 to 2.24 ± 0.56, 1.47 ± 0.54, and 1.07 ± 0.54). Conclusion: This study confirmed that inactivity during 70 days of head-down bed rest adversely affects metabolic health. The daily exercise countermeasures were beneficial but not completely protective of bed rest induced decrements in metabolic health. Supplementary countermeasures such as testosterone may provide additional benefits not provided by exercise alone.

Incentive sensitization for exercise reinforcement to increase exercise behaviors.

Individuals can be sensitized to the reinforcing effects of exercise, although it is unknown if this process increases habitual exercise behavior. Sedentary men and women (body mass index: 25-35 kg/m2, N = 52) participated in a 12-week aerobic exercise intervention. Exercise reinforcement was determined by how much work was performed for exercise relative to a sedentary alternative in a progressive ratio schedule task. Habitual physical activity was assessed via accelerometry. Post-intervention increases in exercise reinforcement predicted increases in physical activity bouts among those who expended over 2000 kcal per week in exercise and who compensated for less than 50 percent of their exercise energy expenditure.

ENERGY BALANCE AND VITAL SIGNS IN PEDIATRIC PATIENTS

BACKGROUND:Prior studies have shown that vital signs such as heart rate, blood pressure and body temperature are depressed in patients with an eating disorder who have experienced a negative energy balance for a significant amount of time. More recently, a negative energy balance has been the focus of Relative Energy Deficiency in Sport (RED-S), which links energy availability to the health of multiple body systems in adults in as little as 5 days with a negative energy balance. High rates of disordered eating patterns have been reported in high school athletes. As adolescents grow, the consequences of a negative energy balance can be significant and potentially irreversible. Thus, vital signs may help clinicians quickly evaluate a patient’s energy status or highlight them for further evaluation.PURPOSE:The purpose of this study was to examine energy balance and vital signs in a cohort of adolescents who were seen by a sports dietitian to gain weight or optimize sports performance.METHODS:We evaluated 240 subjects, 83% female, average age 15.0±2.3 years. Heart rate and blood pressure were measured with a dynamometer in a seated position. Body temperature was measured orally. Height and weight were recorded. BMI was then calculated and evaluated by percentile. Energy intake was assessed using a 3-day food recall log. Energy expenditure was calculated using Harris Benedict Equation and combined with estimated exercise energy expenditure. Energy balance was estimated as energy intake minus energy expenditure.RESULTS:Average age was 15.03±2.71. 85% were female. 30% were below the 15th percentile for BMI. There were no differences in BMI percentiles between males and females (p=0.99). The average heart rate was 71.62±13.4 bpm and 19% were below the 10th percentile for heart rate. Average systolic blood pressure was 110±11 mm Hg and average diastolic blood pressure was 62±7 mmHg. Average temperature was 98.1±.4 degrees F. 88%were in a negative energy balance with an average energy deficit of 552±511 calories. There were no statistically significant differences in energy balance between males and females (p=0.08).CONCLUSIONS:A disproportional number of children with low BMI and heart rate percentiles was observed, which may indicate a long-standing energy deficiency. We also found a high proportion of adolescents who experienced a standalone negative energy balance itself or vital signs consistent with a negative energy balance. Additional studies are needed to study the relationships between energy deficit magnitude and duration in adolescents and children.

The Effect of Exercise Training on Total Daily Energy Expenditure and Body Composition in Weight-Stable Adults: A Randomized, Controlled Trial.

The present study examined, among weight-stable overweight or obese adults, the effect of increasing doses of exercise energy expenditure (EEex) on changes in total daily energy expenditure (TDEE), total body energy stores, and body composition. Healthy, sedentary overweight/obese young adults were randomized to one of 3 groups for a period of 26 weeks: moderate-exercise (EEex goal of 17.5kcal/kg/wk), high-exercise (EEex goal of 35kcal/kg/wk), or observation group. Individuals maintained body weight within 3% of baseline. Pre/postphysical activity between-group measurements included body composition, calculated energy intake, TDEE, energy stores, and resting metabolic rate. Sixty weight-stable individuals completed the protocols. Exercise groups increased EEex in a stepwise manner compared with the observation group (P < .001). There was no group effect on changes in TDEE, energy intake, fat-free mass, or resting metabolic rate. Fat mass and energy stores decreased among the females in the high-exercise group (P = .007). The increase in EEex did not result in an equivalent increase in TDEE. There was a sex difference in the relationship among energy balance components. These results suggest a weight-independent compensatory response to exercise training with potentially a sex-specific adjustment in body composition.

Low Energy Availability in Athletes 2020: An Updated Narrative Review of Prevalence, Risk, Within-Day Energy Balance, Knowledge, and Impact on Sports Performance.

Low energy availability (EA) underpins the female and male athlete triad and relative energy deficiency in sport (RED-S). The condition arises when insufficient calories are consumed to support exercise energy expenditure, resulting in compromised physiological processes, such as menstrual irregularities in active females. The health concerns associated with longstanding low EA include menstrual/libido, gastrointestinal and cardiovascular dysfunction and compromised bone health, all of which can contribute to impaired sporting performance. This narrative review provides an update of our previous review on the prevalence and risk of low EA, within-day energy deficiency, and the potential impact of low EA on performance. The methods to assess EA remain a challenge and contribute to the methodological difficulties in identifying “true” low EA. Screening female athletic groups using a validated screening tool such as the Low Energy Availability in Females Questionnaire (LEAF-Q) has shown promise in identifying endurance athletes at risk of low EA. Knowledge of RED-S and its potential implications for performance is low among coaches and athletes alike. Development of sport and gender-specific screening tools to identify adolescent and senior athletes in different sports at risk of RED-S is warranted. Education initiatives are required to raise awareness among coaches and athletes of the importance of appropriate dietary strategies to ensure that sufficient calories are consumed to support training.

Association between regular aerobic exercise and hyperhomocysteine in hypertensive patients

ABSTRACT Objective The relationship between total plasma homocysteine (tHcy) and exercise remains controversial. This study aimed to investigate the association between regular aerobic exercise and hyperhomocysteine (hHcy) in patients with hypertension. Methods A total of 497 hypertensive patients from 7 communities of Nanjing were enrolled in this cross-sectional study. All participants were asked to complete standard questionnaires by themselves. Physical and laboratory examination were performed within 1 week after enrollment. The association between regular aerobic exercise and hHcy in hypertensive patients was estimated by a multiple logistic regression analysis. Results Of the 497 patients, 210 had a regular aerobic exercise habit and 274 of them were detected with hHcy. Multivariate analysis revealed that exercisers have less risk of hHcy (adjusted odds ratio [OR] 0.42, 95% confidence interval [CI] 0.26–0.66) as compared to non-exercisers controlling for the established and potential confounders. Intensity, frequency, and total energy expenditure of aerobic exercise were found to be independently associated with lower hHcy risk in hypertensive patients. Gender subgroup analyses showed that this inverse relationship between regular aerobic exercise and hHcy exists in both male and female groups (adjusted OR 0.41 95%CI 0.21–0.80, and adjusted OR 0.40 95%CI 0.20–0.80, respectively). Conclusions Regular aerobic exercise has a negative association with hHcy in this cross-sectional study. That suggests a hypothesis that doing aerobic exercise might decrease the risk of hHcy in hypertensive patients.

The energy requirements of performance horses in training.

The aim of this study was to estimate the energy requirements of performance horses in active, variable training in the field. Sixty horses in England and Switzerland were measured over 2-wk periods and, for 15 of these, the measurement period was extended, ranging from 21 to 42 wk. Energy intake was estimated by measuring daily feed consumption. Energy output was measured using heart rate (HR) monitors during 608 training sessions, relating HR to volume of oxygen (VO₂) and converting VO₂ to energy. Field maintenance requirements were calculated by deducting the marginal energy cost of training from energy input. The mean field maintenance expenditure for performance horses with a normal temperament was found to be 0.118 MJ of metabolizable energy (ME) per kilogram of body weight (BW) per day (SD = 0.008, CI = 0.005, n = 60 horses). This result is between 1.9% (P = 0.086) and 20.9% (P < 0.001) greater than the official guidance found in the United States, France, Germany, and Holland. Heart rate monitoring of training revealed a mean energy expenditure (EE) per ridden session of 0.023 MJ ME (SD = 0.001, CI = 0.001, n = 175 training sessions). The mean daily EE for exercise based on a full week’s training was 0.018 MJ ME/kg BW/d (SD = 0.005, CI = 0.001, n = 60 horses), representing a multiple of maintenance of 15.3%. This implies that the official guidance in the United States and France may overstate expenditure for exercise by 111% and 15%, respectively (P < 0.01). Daily EE between countries and within disciplines was consistent, allowing for the creation of user-friendly tables that can be used in budgeting the energy component of diets.

Association between physical activity, cardiorespiratory fitness, and body composition with menopausal symptoms in early postmenopausal women.

The aim of this study was to investigate the relationship between daily physical activity (daily activities, exercise, and sitting time), cardiorespiratory fitness (CRF), and body composition (body mass index [BMI], waist to hip ratio [WHR)] with menopausal symptoms and to determine the strongest predictor(s) of menopausal symptoms. The Menopause Rating Scale questionnaire was used to examine somatic, psychological, urogenital, and total symptoms of menopause. The energy expenditure of daily physical activity, exercise, and sitting time was measured by the International Physical Activity Questionnaire, and CRF was measured by estimating the maximal oxygen intake (VO2max) through the Rockport test. Statistical methods of the Pearson correlation coefficient and hierarchical multiple linear regression were used for data analysis. Fifty-six women, aged 50 to 65 years, voluntarily participated in the study. Exercise energy expenditure was inversely correlated with total (r = -0.403, P = 0.002), somatic (r = -0.293, P = 0.023), and urogenital (r = -0.343, P = 0.009) symptoms of menopause. VO2max was inversely correlated with urogenital symptoms of menopause (r = -0.414, P = 0.002). WHR was positively correlated with somatic symptoms of menopause (r = 0.286, P = 0.032); sitting was correlated with total (r = 0.40, P = 0.002), somatic (r = 0.325, P = 0.015), and psychological (r = 0.274, P = 0.015) symptoms of menopause. Among the study variables, sitting (β=0.365, P = 0.004) and VO2max (β=-0.286, P = 0.030) were the most important predictors of total symptoms of menopause; sitting was the predictor of somatic symptoms (β=0.265, P = 0.045), and VO2max was the predictor of urogenital symptoms of menopause (β=-0.332, P = 0.014). The inclusion of age, BMI, WHR, and duration of menopause as confounding variables in regression analysis did not change the findings related to the predictions of menopausal symptoms. Reducing sitting time, improving VO2max, decreasing WHR, and exercise can be recommended by priority to alleviate menopausal symptoms. Considering the small number of participants in this investigation, future studies are, however, recommended.