ENERGY COST OF RESISTANCE TRAINING IN OBESE, PRE-DIABETIC, POSTMENOPAUSAL WOMEN.

BACKGROUND: Energy expenditure (EE) from exercise is a minor but important consideration in the context of total daily energy demands and plays a role in weight management strategies. This has not been well characterized for resistance training (RT). The purpose of this study was to measure the EE of RT in post-menopausal, pre-diabetic, obese women. Understanding the energy cost of RT in this population will provide valuable to inform health professionals aiming to understand overall energy demands of RT and the application to weight management. METHODS: Nine pre-diabetic, postmenopausal women (50-70 years old, 96.4 ±7.9 kg) completed the resistance training (RT) portion of a larger study approved by FSU Human Subjects Committee. Participant screenings prior to RT excluded those with a blood pressure \u3e140/90 mmHg; type I or type II diabetes; medical contraindications to exercise; recent musculoskeletal disease or injury (\u3c6 months); history of, or current cancer, CVD, respiratory disease, uncontrolled thyroid dysfunction, liver or renal dysfunction; use of tobacco products or medications affecting lipid metabolism; and/or diagnosis with an eating disorder. Participants needed to have a Body Mass Index of 30-39.9 kg/m2, a waist circumference \u3e 88.0 cm, meet at least one criterion of prediabetes (HbA1c 5.7 - 6.4%, fasting blood glucose 100-125 mL/dL, and/or 2-hr OGTT blood glucose 140-199 mg/dL), and be sedentary with a stable bodyweight (\u3c ±2 kg in preceding 6 months). RT involved a circuit of seven machine-based resistance exercises: chest press, horizontal leg press, cable seated row, quad extension, shoulder press, seated hamstring curl, and cable biceps curl. A 10-repetition maximum lift (10RM) was tested for all exercises one week prior to RT. The participants lifted their 10RM for all sets of all exercises. Metabolic rate was measured using a metabolic cart during RT. Each RT session ended when the subject expended 200 kcal. The first ten and final six minutes were discarded from the data set when calculating average EE. RESULTS: The average EE in the RT group was 1.47± 0.33 kcal/min. Interestingly, the EE did not significantly correlate with participant’s bodyweight (r = 0.37, p=0.32), weekly training load (r = 0.10, p = 0.80), or relative strength (r = 0.02, p=0.97). CONCLUSIONS: The results suggest that the EE of post-menopausal, pre-diabetic, obese women during RT is 1.47± 0.33 kcal/min. Grant or funding information: 1 R01 DK125728-01

12 WEEKS OF RESISTANCE EXERCISE TRAINING OR ENDURANCE EXERCISE TRAINING HAS NO EFFECT ON ENERGY EXPENDITURE BEFORE, DURING, OR AFTER AN ACUTE BOUT OF WALKING EXERCISE IN SEDENTARY POSTMENOPAUSAL WOMEN WITH OBESITY AND PREDIABETES.

BACKGROUND: Prediabetes, often seen alongside obesity and as a precursor to type 2 diabetes, is prevalent in over 50% of women aged 60 years and above. The metabolic health benefits of exercise are widely acknowledged; however, a clear understanding of metabolic changes induced by resistance training (RT) compared to endurance training (ET) is lacking, particularly in older women. Furthermore, it is unclear what the effects are of 12 weeks of RT or ET training on metabolic activity before, during, and after general physical activities, like walking. OBJECTIVE: To investigate the impacts of 12-week energy-matched RT or ET on energy expenditure before (resting metabolic rate (RMR)), during, and after an acute bout of walking exercise in postmenopausal women with obesity and prediabetes. METHODS: The study included postmenopausal women with obesity and prediabetes that participated in an ongoing larger study of fat metabolism (n =15; mean ± SD: age: 59 ± 6 yrs.; BMI: 35.17. ± 3.53 kg/m2; BF: 46.87 ± 3.94%). Participants were randomized to 12-weeks of ET (n = 7) or RT (n = 8). In addition, six participants (n=3ET, n=3RT) were randomized for an acute bout of low-intensity (50% VO2 peak) treadmill exercise before and after the 12-weeks of training. Energy expenditure before, during, and after an acute bout of exercise at the same absolute intensity were assessed using indirect calorimetry. All study outcomes were assessed before (PRE) and following (POST) 12 weeks of ET or RT. Statistical analyses with Statistical Analysis System (SAS) using marginal models to determine the main effect of time and training (RT or ET) on study outcomes. Post hoc analyses were adjusted for multiple comparisons using the Bonferroni adjustment with α set at 0.05. RESULTS: No differences between study outcomes were present between RT and ET. At POST, as compared to PRE, there were no differences in RMR (n=15; POST: 1496.25 ± 266.66 vs PRE: 1452.30 ± 150.34 kcal/day; p=0.722), exercise energy expenditure (n=6; POST: 228.85 ± 89.77 vs. PRE: 246.98 ± 67.38 kcals; p=0.695) or acute 10 minute post-exercise energy expenditure (n=6; POST: 14.25 ± 2.67 vs. PRE: 16.39 kcal/day; p=0.237). CONCLUSIONS: When the energy expenditure of exercise training is matched, 12 weeks of either ET or RT do not distinctly alter energy expenditure before, during, or after an acute bout of walking exercise in sedentary postmenopausal women with obesity and prediabetes

PRE-LOADED BETAINE IMPROVES THERMOREGULATION WHEN CYCLING IN THE HEAT

BACKGROUND: Heat-related illness compromises health and performance in endurance athletes during training and competition. Betaine (BET) is a nutrient that has been previously identified in animal models to act as an osmolyte and attenuates the effects of thermal stress. However, much of the prior research has only assessed the efficacy of preloading BET in passive heat models. Therefore, the purpose of this study is to examine the effects of preloaded BET in an active heat model. METHODS: Eight endurance-trained males (age 26.4 ± 6.8 years; VO2 Peak 55.5 ± 4.8 mL/kg/min) completed 60 min of cycling at 70% VO2 peak in a hot environment (33° C, 35% RH) after a 7-day supplement loading protocol (50 mg/kg, 2x daily) of placebo (PLA) or BET in a double blind, randomized, counterbalanced, crossover study. Core temperature and thermal sensation were measured at rest and every 10 minutes throughout the active heat protocol. Nude body weight was measured prior to- and immediately post-exercise to calculate sweat rate. No fluid ingestion was allowed during this time. Blood samples were collected at rest, 30 minutes, and immediately after exercise. Visual analog scales were administered before and immediately after exercise to quantify sensations of thirst. Bioelectrical impedance assessed fluid compartments before and after the respective supplementation weeks. RESULTS: Area under curve analysis identified BET as having a smaller overall increase in core body temperature compared to PLA (p = 0.012). Further analysis showed ending core temperature was significantly lower in BET (-0.023 ° C; p = 0.029) than PLA. BET also resulted in a significant increase in sweat rate (mean difference = 0.19 ± 0.20 L/hr; p = 0.02). Blood assessments revealed BET had lower hematocrit at the mid-exercise timepoint compared to PLA (BET: 48.3%; PLA: 50.8%; p = 0.02). Increases in total body water (TBW) and intracellular fluid (ICF) in the BET condition approached significance compared to PLA (TBW: +1.69 L, p = 0.055; ICF: +1.39L, p = 0.066). No significant differences were found between conditions in subjective measures of thermal sensation or thirst (p = 0.318; p = 0.862). CONCLUSION: BET supplementation may have the capacity to mitigate the rise in core body temperature and maintain plasma volume during exercise in an uncompensable heat stress environment, despite having no significant effect on subjective sensations of heat stress