ECSS Paris 2023: OP-PN02
INTRODUCTION: Insufficient sleep can negatively impact training, performance, and increase injury risk in active populations. Consequently, strategies to improve sleep in active populations have been gaining popularity. Tryptophan (TRP), an amino acid and precursor for serotonin and melatonin metabolism has been established for its sleep augmenting benefits. However, pure TRP is regulated as a prescription medicine in Australia. Alpha-lactalbumin (ALAC), is a whey protein with high TRP (4.8 mg/g) content and has been assessed for its effects on mood, alertness, and sleep outcomes. However, there is a lack of consensus on the dose and timing of consuming ALAC for optimising TRP availability. The present study aims to define the dose of ALAC required to saturate the plasma TRP and TRP:LNAA ratio, over a 210 min time course. METHODS: Sixteen healthy active adults, aged 18-35 years, completed this double-blinded randomised crossover trial. Participants visited the Deakin lab on four different occasions with a gap of 2.5 hours from their last meal. Each visit involved consuming a single evening dose of ALAC (10 g, 20 g, 30 g, and 40 g) in a random latin square order. In a crossover manner, each participant received all doses, separated by a washout period. Venous blood samples were collected at five time points up to 210 min post-consumption. Visual Analogue Scales were provided to assess sensory preferences and gastrointestinal (GI) symptoms associated with the four ALAC doses. The plasma TRP:LNAA ratio time-course was analysed using mixed models adjusting for sex, body weight, and baseline. RESULTS: Across all doses the apparent peak for TRP and TRP:LNAA ratio occurred at 120-180 min post consumption and were significantly different from baseline for 30 g and 40 g doses of ALAC (p<0.02). Pairwise comparisons of plasma TRP levels at 120 and 180 min confirmed that 30 and 40 g produced significantly higher TRP concentrations than 10 g (p<0.01) or 20 g (p<0.02). A similar trend was observed with 30 g ALAC on the plasma TRP:LNAA ratio at the apparent peak of 180 min (p<0.02). However, no significant differences were reported in TRP concentrations and TRP:LNAA ratio between higher doses of 30 g and 40 g (p=0.30). This indicates that 30 g of ALAC may be a saturating dose for both TRP and TRP:LNAA ratio. Additionally, AUC analysis for the time course at each dose reported similar trends, reinforcing evidence of a saturation effect on TRP concentrations and TRP:LNAA at 30 g of ALAC . There were no significant differences in the sensory attributes and GI symptoms reported across the time course for all doses, indicating that dosing up to 40 g is equivalent for digestive comfort to dosing at 10 g of ALAC. CONCLUSION: Our findings indicate that 30 g ALAC has a saturating effect on the plasma TRP concentrations and the TRP:LNAA ratio, producing an apparent peak at 180 min post-consumption. These data may support the optimisation of ALAC timing and dosing for associated sleep, mood and cognitive enhancement.
Read CV Luana A MascarenhasECSS Paris 2023: OP-PN02
INTRODUCTION: Chronic Kidney Disease (CKD) is characterized by a progressive decline in kidney function which has widespread effects on various organ systems including skeletal muscle. By the time renal replacement therapy is required, most patients have become so deconditioned that opportunities for exercise participation are very limited. Therefore, lifestyle interventions focused at maintaining or improving muscle health should be implemented at an earlier stage in the disease process. The present study compares the capacity of skeletal muscle tissue to respond to resistance exercise and protein supplementation between patients with CKD and healthy matched controls. METHODS: Twenty patients with advanced CKD but not on dialysis (stage G3b-G4, 3F/17M, age 66±13 y, BMI 30±5 kg/m2) and twenty sex-, age-, and BMI-matched controls (CON; 3F/17M, age 65±14 y, BMI 29±4 kg/m2) participated in this study. Baseline assessments included cardiopulmonary exercise testing, leg strength, and dual-energy x-ray absorptiometry. In a randomized cross-over design, participants followed their habitual lifestyle for 7 days and completed a 7-day intervention composed of 3 resistance exercise sessions with post-exercise ingestion of 20 g protein. To assess muscle protein synthesis rates, participants ingested deuterium oxide (2H2O) throughout the study period with blood and muscle samples being collected before (t=0) and after the first (t=7) and second week (t=14). Furthermore, mitochondrial respiration was assessed in muscle tissue obtained before and after the intervention. Cross-sectional and longitudinal data were compared using independent t-tests and two-way repeated measures ANOVA, respectively. RESULTS: Patients with advanced CKD were characterized by lower aerobic capacity compared with CON (21.3±5.9 vs 30.3±11.2 mL/kg/min, respectively; P=0.004), whereas lean mass (59±7 vs 61±11 kg, P=0.592) and leg strength (95±30 vs 106±44 kg, P=0.358) did not differ between groups. Maximal mitochondrial respiration was lower in patients with CKD compared with CON at baseline (376±71 vs 443±128 pmol/s/mg dry wt, respectively; P=0.048) and increased following the exercise intervention in both groups (408±94 vs 459±132 pmol/s/mg dry wt, respectively; P-time=0.025) with no differences in the responsiveness between groups (P-time*group=0.453). In line, habitual muscle protein synthesis rates were lower in CKD vs CON (1.13±0.23 vs 1.33±0.36 %/d, respectively; P=0.046) and were ~20% higher during the exercise intervention week in both groups (1.35±0.25 vs 1.60±0.39 %/d, respectively; P-time<0.001, P-time*group=0.675). CONCLUSION: Skeletal muscle in patients with CKD remains highly responsive to resistance exercise plus protein supplementation, with rapid increases in muscle protein synthesis rates and mitochondrial respiration. Exercise and nutritional prehabilitation seems warranted for CKD patients prior to the onset of renal replacement therapy.
Read CV Dion HoutvastECSS Paris 2023: OP-PN02
INTRODUCTION: Overweight is a global concern, affecting more than half of the Danish population. A calorie restricted diet combined with physical activity is considered optimal for weight loss and improving cardiovascular and metabolic health, including muscle mass maintenance and cellular adaptations. Carbohydrate (CHO)-restricted diets, such as the ketogenic diet, have become increasingly popular for weight loss and metabolic health, but their impact on physical capacity remain unclear. This study investigated how a very low CHO (VLCHO) diet combined with caloric restriction affects weight loss, physical capacity and metabolic parameters. METHODS: Forty healthy young women (BMI 25–30 kg·m⁻²) were randomized to 12 days of VLCHO (0.3 g CHO·kg⁻¹·day⁻¹) or a moderate CHO diet (MCHO) (2.5–3.0 g CHO·kg⁻¹·day⁻¹), both with a 1000 kcal·day⁻¹ deficit and 1.4 g protein·kg⁻¹·day⁻¹. Participants completed three supervised bike sessions between baseline (pre) and day 11 (post 1). Body composition, resting metabolic rate (RMR), substrate utilization, blood markers, muscle biopsies, and performance were assessed pre and post 1. Performance was reassessed on day 13 (post 2) following a CHO-rich breakfast. RESULTS: VLCHO reduced daily blood glucose and increased ketones compared with MCHO (group × time, P<0.001). Body weight decreased more in VLCHO (–3.3 vs –1.3 kg; group × time, P<0.001). FFM declined in VLCHO (–2.1 kg; P<0.001) but was preserved in MCHO (group × time, P<0.001). Total body water decreased only in VLCHO (group × time, P<0.001). Fat mass decreased similarly between groups, whereas body fat percentage decreased only in MCHO (group × time, P=0.006). At post 1, time to exhaustion decreased in VLCHO (–52 s; P=0.018) but not in MCHO (group × time, P=0.001). At (post 2), VLCHO returned to baseline, whereas MCHO showed a net improvement from pre (+101 s; P<0.001). Peak sprint power declined in VLCHO at post 1 (–52.8 W; P<0.001) and remained lower at post 2 (net –32.3 W; P=0.017), whereas MCHO increased at post 1 (+30.0 W; P=0.035) with no net change at post 2 (group × time, P<0.001). Average sprint power decreased in VLCHO at post 1 (P=0.009) with no significant net change at post 2. Peak fat oxidation increased more in VLCHO (group × time, P=0.005) and remained elevated at post 2. Respiratory quotient decreased only in VLCHO (group × time, P=0.010). RMR decreased in MCHO (P=0.008) but not in VLCHO. CONCLUSION: VLCHO during short-term energy restriction induced pronounced metabolic adaptations, including ketosis and increased fat oxidation, but at the expense of FFM and high-intensity performance. These impairments were only partially restored after acute CHO refeeding. In contrast, MCHO preserved lean mass and improved endurance capacity. CHO availability critically modulates the balance between metabolic adaptation and functional performance during caloric restriction.
Read CV Søren SkriverECSS Paris 2023: OP-PN02