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Janice L. Thompson

Very little is known about the energy needs of young athletes. Recent studies using the doubly labeled water method have shown that the recommended dietary allowances for energy may be too high for normally active children and adolescents living in affluent societies. No studies of energy balance in young athletes have been published. Self-report dietary records of young athletes indicate that energy, carbohydrate, and select micronutrient intakes of certain athletic groups and individual athletes may be marginal or inadequate. Potential consequences of inadequate energy and nutrient intakes in young athletes include poor bone health, fatigue, limited recovery from injuries, menstrual dysfunction in female athletes, and poor performance. Studies of energy balance and nutrient status in young athletes are needed to better understand the nutritional needs of this group.

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Eric T. Poehlman and Christopher Melby

In this brief review we examine the effects of resistance training on energy expenditure. The components of daily energy expenditure are described, and methods of measuring daily energy expenditure are discussed. Cross-sectional and exercise intervention studies are examined with respect to their effects on resting metabolic rate, physical activity energy expenditure, postexercise oxygen consumption, and substrate oxidation in younger and older individuals. Evidence is presented to suggest that although resistance training may elevate resting metabolic rate, il does not substantially enhance daily energy expenditure in free-living individuals. Several studies indicate that intense resistance exercise increases postexercise oxygen consumption and shifts substrate oxidation toward a greater reliance on fat oxidation. Preliminary evidence suggests that although resistance training increases muscular strength and endurance, its effects on energy balance and regulation of body weight appear to be primarily mediated by its effects on body composition (e.g., increasing fat-free mass) rather than by the direct energy costs of the resistance exercise.

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Mindy Patterson, Wanyi Wang, and Alexis Ortiz

physiological decline that occurs with aging, energy balance as indicated by adequate dietary intake and energy expenditure (EE) by means of physical activity (PA) after the age of 50 can help sustain appropriate body composition thus overall health and quality of life ( American College of Sports Medicine et

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Lore Metz, Laurie Isacco, Kristine Beaulieu, S. Nicole Fearnbach, Bruno Pereira, David Thivel, and Martine Duclos

been investigated ( Barbosa et al., 2007 ; Pendergast et al., 2015 ), little is known regarding its influence on energy balance (EB) despite its increasing popularity especially with women wishing to improve their body composition. Although exercise induces increased EE, it is now well established

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James O. Hill and Reneé Commerford

In this paper, we review the impact of physical activity on energy and maeronutrient balances. Stability of body weight and body composition depends on reaching a steady-state where the amount and composition of energy ingested are equal to the amount and composition of energy expended. We describe how a person's level of physical activity can have a significant impact on determining the level of body weight and body fatness at which that steady-state is reached. First, physical activity can directly affect both total energy intake and total energy expenditure. Physical activity can also affect fat balance, and it is becoming clear that imbalances in total energy are largely imbalances in fat. High levels of physical activity should help individuals reach fat and energy balances at lower levels of body fatness than would have been achieved at lower levels of physical activity.

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Keren Susan Cherian, Ashok Sainoji, Balakrishna Nagalla, and Venkata Ramana Yagnambhatt

Determination of energy adequacy and nutritional status of adolescent athletes has been emphasized by researchers worldwide ( 33 , 60 ). Adolescent athletes are at a crucial age, requiring energy for training apart from growth. Thus, young athletes need to maintain a positive energy balance (EB

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Senlin Chen and Ang Chen

Expectancy beliefs and task values are two essential motivators in physical education. This study was designed to identify the relation between the expectancy-value constructs (Eccles & Wigfield, 1995) and high school students’ physical activity behavior as associated with their energy balance knowledge. High school students (N = 195) in two healthful-living programs (i.e., combination of physical and health education) responded to measures of expectancy-value motivation, energy balance knowledge, in-class physical activity, and after-school physical activity. The structural equation modeling confirmed positive impact from expectancy beliefs and interest value to in-class physical activity (Path coefficient range from .19 to .26, ps < .01). Cost perception was found exerting a negative impact on after-school physical activity but a positive one on lower level of understanding of energy balance (Path coefficient range from -.33 to -.39, ps < .01). The findings painted a complex but meaningful picture about the motivational impact of expectancy-value constructs on physical activity and energy balance knowledge. School healthful-living programs should create motivational environments that strengthen students’ expectancy beliefs and interest value and alleviate their negative perceptions and experiences.

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Karen J. Reading, Linda J. McCargar, and Vicki J. Harber

Menstrual abnormalities are associated with negative energy balance and reduced energy expenditure (REE). To examine this relationship in elite adolescent aesthetic athletes, 3 groups of females (aged 15-18 years) were studied: 10 oligo/amenorrheic athletes (OA), 11 eumenorrheic athletes (EA), and 8 non-athlete controls (C). Components of energy balance, body composition, dietary restraint, pubertal maturation, and luteal phase salivary progesterone were assessed in all groups. Both groups of athletes had a later age of menarche and lowerpubertal development score compared to the non-athletes (p < .05). With the exception of salivary progesterone (ng/ml; OA = 0.15±0.01 <EA = 0.29± 0.1 and C = 0.30 ± 0.13, /p = .007), there were no differences between the athlete groups. Energy balance (kcal/d) in the OA group was lower (−290 ± 677) compared to either EA (−5±461) or C (179 ± 592) but did not reach significance (p = .24). Dietary energy intake and absolute REE (kcal/d) were not different among groups, despite detectable differences in reproductive status, and thus could not be attributed to differences in energy balance or REE.

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Nicholas E. Kimber, Jenny J. Ross, Sue L. Mason, and Dale B. Speedy

Energy balance of 10 male and 8 female triathletes participating in an Ironman event (3.8-km swim, 180-km cycle, 42.2-km run) was investigated. Energy intake (EI) was monitored at 7 designated points by dietary recall of food and fluid consumption. Energy expenditure (EE) during cycling and running was calculated using heart rate-V̇O2 regression equations and during swimming by the multiple regression equation: Y = 3.65v + 0.02 W − 2.545 where Y is V̇O2 in L · min−1, v is the velocity in m · s−1, Wis the body weight in kilograms. Total EE (10.036 ± 931 and 8570 ± 1014 kcal) was significantly greater than total El (3940 ± 868 and 3115 ± 914kcal, p < .001) formales and females, respectively, although energy balance was not different between genders. Finishing time was inversely related to carbohydrate (CHO) intake (g · kg−1 · h−1) during the marathonrun formales (r=−.75, p < .05), and not females, suggesting that increasing CHO ingestion during the run may have been a useful strategy for improving Ironman performance in male triathletes.

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Bjoern Geesmann, Jenna C. Gibbs, Joachim Mester, and Karsten Koehler

Ultraendurance athletes often accumulate an energy deficit when engaging in ultraendurance exercise, and on completion of the exercise, they exhibit endocrine changes that are reminiscent of starvation. However, it remains unclear whether these endocrine changes are a result of the exercise per se or secondary to the energy deficit and, more important, whether these changes can be attenuated by increased dietary intake. The goal of the study was to assess the relationship between changes in key metabolic hormones after ultraendurance exercise and measures of energy balance. Metabolic hormones, as well as energy intake and expenditure, were assessed in 14 well-trained male cyclists who completed a 1230-km ultraendurance cycling event. After completion of the event, serum testosterone (–67% ± 18%), insulin-like growth factor-1 (IGF-1) (–45% ± 8%), and leptin (–79% ± 9%) were significantly suppressed (P < .001) and remained suppressed after a 12-h recovery period (P < .001). Changes in IGF-1 were positively correlated with energy balance over the course of the event (r = .65, P = .037), which ranged from an 11,859-kcal deficit to a 3593-kcal surplus. The marked suppression of testosterone, IGF-1, and leptin after ultraendurance exercise is comparable to changes occurring during acute starvation. The suppression of IGF-1, but not that of other metabolic hormones, was strongly associated with the magnitude of the energy deficit, indicating that athletes who attained a greater energy deficit exhibited a more pronounced drop in IGF-1. Future studies are needed to determine whether increased dietary intake can attenuate the endocrine response to ultraendurance exercise.