Resting Metabolic Rate and Thermogenic Effect of Glucose in Trained and Untrained Girls Age 11-15 Years

Abstract

Twelve girls who trained in rowing were examined twice a year for 4 years. Their initial age was 11.7 ± (SD) 0.2 yrs. Control groups consisted of 13 girls age 11.5±0.3 yrs and 18 girls age 14.4±0.3 yrs examined simultaneously with trained girls in the first and last year of the study, respectively. The examination involved basic anthropometry, estimation of sexual maturation (Tanner scale), 2-day food records, measurements of resting metabolic rate, energy expenditure following glucose ingestion (50 g), and determinations of blood glucose and plasma insulin concentrations prior to and 2 hrs after glucose load. Body mass, height, and fat content were slightly greater in trained girls. None of the subjects reported disturbances in menstrual function, and the age of menarche was similar for all. Both trained and untrained girls reported similar daily energy intake closer to the lower limit or slightly below the estimates of energy requirements for adolescents. Resting metabolic rate calculated per kg of total body mass or lean body mass was lower in trained girls, while the thermogenic effect of glucose was greater. Plasma insulin concentrations measured 2 hrs after glucose ingestion were lower in trained girls. The results suggest that in circumpubertal girls, increased physical activity leads to energy conservation at rest in postabsorptive state and a tendency toward enhancement of food-induced thermogenesis.

Effects of Exercise Training on Resting Energy Expenditure and Lean Mass During Pediatric Burn Rehabilitation

“…It has also been postulated that the effect of an exercise intervention on energy expenditure decreases with time as efficiency at the exercise improves (36, 37). Finally, a study reported a decrease in REE (normalized to LBM) in adolescent girls participating in rowing training, compared to their non-training peers over a four year study period (35). …”

Increasing Energy Flux to Maintain Diet-Induced Weight Loss

“…Definitive conclusions remain elusive due to tremendous inconsistencies in experimental methodology, such as variation in meal size, macro-nutrient composition, and training/activity status of study populations. Still, compared with sedentary adults, many studies have shown TEF to be appreciably greater in habitual exercisers [72,73,74,75,76,77]. Importantly, this favorable consequence of habitual exercise appears evident irrespective of whether the exercise modality comprises endurance [73,74,75] or resistance training [76].…”

“…The latter declines as less energy is required to move the lower body mass, and as skeletal muscle work efficiency increases. [71,72,89].…”

“…Also, PAEE declines, presumably resulting from less movement and the fact that less energy is required to move the lower body mass. Importantly, the increased skeletal muscle work efficiency continues during weight loss maintenance such that less energy is expended for a given low intensity physical activity [71,72]. Rosenbaum et al [72] have estimated that as much as one-third of the decline in PAEE with diet-induced weight loss occurs as a result of this increased skeletal muscle work efficiency.…”

“…Importantly, the increased skeletal muscle work efficiency continues during weight loss maintenance such that less energy is expended for a given low intensity physical activity [71,72]. Rosenbaum et al [72] have estimated that as much as one-third of the decline in PAEE with diet-induced weight loss occurs as a result of this increased skeletal muscle work efficiency. Hill and colleagues have proposed the usefulness of the energy gap concept for weight loss maintenance [90].…”