Resting metabolic rate and post-prandial thermogenesis by level of aerobic power in older athletes

Nutrition for Older Athletes: Focus on Sex-Differences

Regular physical exercise and a healthy diet are major determinants of a healthy lifespan. Although aging is associated with declining endurance performance and muscle function, these components can favorably be modified by regular physical activity and especially by exercise training at all ages in both sexes. In addition, age-related changes in body composition and metabolism, which affect even highly trained masters athletes, can in part be compensated for by higher exercise metabolic efficiency in active individuals. Accordingly, masters athletes are often considered as a role model for healthy aging and their physical capacities are an impressive example of what is possible in aging individuals. In the present review, we first discuss physiological changes, performance and trainability of older athletes with a focus on sex differences. Second, we describe the most important hormonal alterations occurring during aging pertaining regulation of appetite, glucose homeostasis and energy expenditure and the modulatory role of exercise training. The third part highlights nutritional aspects that may support health and physical performance for older athletes. Key nutrition-related concerns include the need for adequate energy and protein intake for preventing low bone and muscle mass and a higher demand for specific nutrients (e.g., vitamin D and probiotics) that may reduce the infection burden in masters athletes. Fourth, we present important research findings on the association between exercise, nutrition and the microbiota, which represents a rapidly developing field in sports nutrition.

Resting Energy Expenditure of Master Athletes: Accuracy of Predictive Equations and Primary Determinants

Resting energy expenditure (REE) is determined mainly by fat-free mass (FFM). FFM depends also on daily physical activity. REE normally decreases with increased age due to decreases in FFM and physical activity. Measuring REE is essential for estimating total energy expenditure. As such, there are a number of different equations in use to predict REE. In recent years, an increasing number of older adults continue to participate in competitive sports creating the surge of master athletes. It is currently unclear if these equations developed primarily for the general population are also valid for highly active, older master athletes. Therefore, we tested the validity of six commonly-used equations for predicting REE in master athletes. In conjunction with the World Masters Athletic Championship in Malaga, Spain, we measured REE in 113 master athletes by indirect calorimetry. The most commonly used equations to predict REE [Harris & Benedict (H&B), World Health Organization (WHO), Müller (MÜL), Müller-FFM (MÜL-FFM), Cunningham (CUN), and De Lorenzo (LOR)] were tested for their accuracies. The influences of age, sex, height, body weight, FFM, training hours per week, phase angle, ambient temperature, and athletic specialization on REE were determined. All estimated REEs for the general population differed significantly from the measured ones (H&B, WHO, MÜL, MÜL-FFM, CUN, all p < 0.005). The equation put forward by De Lorenzo provided the most accurate prediction of REE for master athletes, closely followed by FFM-based Cunningham’s equation. The accuracy of the remaining commonly-used prediction equations to estimate REE in master athletes are less accurate. Body weight (p < 0.001), FFM (p < 0.001), FM (p = 0.007), sex (p = 0.045) and interestingly temperature (p = 0.004) are the significant predictors of REE. We conclude that REE in master athletes is primarily determined by body composition and ambient temperature. Our study provides a first estimate of energy requirements for master athletes in order to cover adequately athletes’ energy and nutrient requirements to maintain their health status and physical performance.

VO2max is associated with measures of energy expenditure in sedentary condition but does not predict weight change

BACKGROUND/OBJECTIVES

Energy expenditure measured under sedentary conditions predicts weight change but evidence that directly measured VO₂max is associated with weight change is lacking. The aim of this study was to determine the associations of VO₂max with measures of predominantly sedentary 24-h thermogenesis, and subsequent weight change.

SUBJECTS/METHODS

Three hundred fifty-seven individuals (162 females; 27 Blacks, 72 Caucasians, and 258 American Indians) had measures of body composition, resting metabolic rate (RMR), and intermittent treadmill run test for assessment of VO₂max. On a separate day, 24-h energy expenditure (EE), diet-induced thermogenesis (DIT) expressed as "awake and fed" thermogenesis (AFT), sleeping metabolic rate (SMR), and spontaneous physical activity (SPA) were measured in a whole-room indirect calorimeter. Follow-up weight for 217 individuals was available (median follow-up time, 9.5 y; mean weight change, 12.4 ± 14.9 kg).

RESULTS

After adjustment for fat free mass, fat mass, age, sex, and race, a higher VO₂max was associated with a higher RMR (β = 68.2 kcal/day per L/min, P < 0.01) and 24-h EE (β = 62.2 kcal/day per L/min, P < 0.05) and including additional adjustment for energy intake higher AFT (β = 66.1 kcal/day per L/min, P = 0.01). Neither SMR (P > 0.2) nor SPA (P > 0.8) were associated with VO₂max. VO₂max at baseline did not predict follow-up weight after adjustment for baseline weight, follow-up time, sex, and race (P > 0.4).

CONCLUSION

VO₂max is associated with measures of EE including 24-h EE, RMR and DIT implying a common mechanism regulating the energetics of skeletal muscle during exercise and thermogenesis. However, this did not translate to VO₂max as a predictor of weight change.

Resting metabolic rate after endurance exercise training

PURPOSE

1) To examine the effect of a 12-wk endurance exercise training program on RMR and 2) to provide insight into the mechanisms responsible for alterations in RMR that may occur after exercise training.

METHODS

Male participants (19-32 yr) in an exercise group (EX; n = 9) performed jogging and/or running 3-4 d x wk(-1), 25-40 min per session, at 60%-80% VO2max, whereas subjects in a control group (CON; n = 10) maintained their normal activity patterns. Body composition, VO2max, RMR, epinephrine, norepinephrine, total thyroxine, free thyroxine, insulin, free fatty acids, and glucose were measured before and after the intervention.

RESULTS

Training resulted in a significant increase in VO2max in EX (46.2 +/- 1.2 to 51.0 +/- 1.3 mL x kg(-1) x min(-1), P < 0.001). Absolute and relative values for RMR did not significantly change in EX after training. Mean values for epinephrine, norepinephrine, total thyroxine, insulin, and glucose did not significantly change in either group; however, free thyroxine decreased significantly after training in EX (P = 0.04). Training also resulted in a significant increase in free fatty acid concentration in EX (0.37 +/- 0.03 to 0.48 +/- 0.04 mmol x L(-1), P < 0.001). RMR in CON decreased significantly when expressed as an absolute value (P < 0.01) and relative to body weight (P < 0.01), fat-free mass (P < 0.01), and fat mass (P = 0.04).

CONCLUSIONS

The mechanism for the decrease in CON is unknown, but it may be related to seasonal variations in RMR. Training may have prevented a similar decline in RMR in EX and may be related to a training-induced increase in fat oxidation.