Betaine has been demonstrated to increase tolerance to hypertonic and thermal stressors. At the cellular level, intracellular betaine functions similar to molecular chaperones, thereby reducing the need for inducible heat shock protein expression. In addition to stabilizing protein conformations, betaine has been demonstrated to reduce oxidative damage. For the enterocyte, during periods of reduced perfusion as well as greater oxidative, thermal, and hypertonic stress (i.e., prolonged exercise in hot-humid conditions), betaine results in greater villi length and evidence for greater membrane integrity. Collectively, this reduces exercise-induced gut permeability, protecting against bacterial translocation and endotoxemia. At the systemic level, chronic betaine intake has been shown to reduce core temperature, all-cause mortality, markers of inflammation, and change blood chemistry in several animal models when exposed to heat stress. Despite convincing research in cell culture and animal models, only one published study exists exploring betaine’s thermoregulatory function in humans. If the same premise holds true for humans, chronic betaine consumption may increase heat tolerance and provide another avenue of supplementation for those who find that heat stress is a major factor in their work, or training for exercise and sport. Yet, this remains speculative until data demonstrate such effects in humans.

We examined the effect of a protein supplement on muscular strength and body composition during 6 months of a 5 days/week concurrent strength and endurance training program. Sedentary males (n = 26) and females (n = 25), 18–25 years, were randomly assigned to receive a protein (PRO, 42 g/serving) or carbohydrate (CON) supplement twice daily. Strength and body composition (dual-energy X-ray absorptiometry) were assessed at baseline, 3 (3M), and 6 (6M) months. Protein intake was higher in PRO (PRO: 2.2 g/kg; CON: 1.1 g/kg; p < .001). Females in both groups gained similar strength at 3M and 6M in bench press and hip sled. Males in PRO gained more bench press strength at 3M (PRO: 24.6 ± 3.2 kg; CON: 14.3 ± 3.8 kg; p = .06) and 6M (PRO: 34.4 ± 4.3 kg; CON: 18.7 ± 5.1 kg; p = .03) and hip sled strength at 3M (PRO: 67.7 ± 9.2 kg; CON: 40.8 ± 10.8 kg, p = .07) and 6M (PRO: 94.0 ± 10.6 kg; CON: 65.1 ± 12.4 kg; p = .09) compared with CON. Females in PRO experienced a greater reduction in fat mass over the course of the study (6M) than CON (PRO: −1.7 ± 0.5 kg; CON: 0.1 ± 0.5 kg; p = .06). Changes in lean mass were similar for females in PRO and CON. Loss in fat mass was similar for males in PRO and CON at 3M and 6M. Males in PRO gained more lean mass at 3M compared with CON (PRO: 3.2 ± 0.3 kg; CON: 2.2 ± 0.4 kg; p = .1) but similar gains at 6M (PRO: 2.6 ± 0.4 kg; CON: 2.2 ± 0.5 kg; p = .6). The results of this study demonstrate that PRO used during a concurrent training program may augment positive changes in body composition in young sedentary males and females, and strength gains in males.

The purpose of this study was to determine the effect of a whole-food protein (cottage cheese, CC) consumed before sleep on next-morning resting energy expenditure (REE), RER and appetite compared with an isoenergetic/isonitrogenous casein protein (CP) supplement and placebo (PL) in active women. In a beverage-blinded, randomised, cross-over design, ten active women (age, 23·1 (sd1·9) years; body fat, 22·0 (sd4·6) %) consumed pre-sleep CC (30 g of protein, 10 g of carbohydrate and 0 g of fat) or energy- and protein-matched liquid CP or PL (0 kJ). Participants arrived at 18.00 hours for an overnight stay in the laboratory. At 30–60 min before normal bed time (2 h post standard meal), participants consumed CC, CP or PL before measurement of REE. Upon waking (05.00–08.00 hours), REE was repeated and subjective appetite was recorded. Statistical analyses were conducted using repeated-measures ANOVA (SPSS). Significance was accepted atP≤0·05. There were no significant differences in acute REE (CC, 7217 (sd1368); CP, 7188 (SD895); PL, 7075 (sd1108) kJ/d,P=0·95), acute RER (0·79 (sd0·05),P=0·56), morning REE (CC, 5840 (sd1225); CP, 5694 (sd732); PL, 5991 (sd903) kJ/d,P=0·79) or morning RER (0·77 (sd0·03),P=0·52). Subjective measures of appetite were not different between groups. In active women, pre-sleep consumption of CC does not alter REE or RER more than a CP or PL beverage. These data suggest that the metabolic response from whole-food protein do not differ from the metabolic response of liquid protein.

Maximal oxygen consumption, 30 min at 75% maximal oxygen consumption, and a 5-km time trial. Thirty minutes before exercise, participants consumed one of three beverages: 1) 75 g low glycemic index modified starch supplement (UCAN), 2) 75 g high glycemic index glucose-based supplement (G), or 3) a flavor-matched noncaloric placebo (PL). SCAAT lipolysis was assessed via microdialysis. Results Before exercise, blood glucose and insulin were elevated with G versus PL (+53.0 ± 21.3 mg·dL−1 (mean ± SD), P < 0.0001; +33.9 ± 11.0 μU·mL−1, P < 0.0001) and G versus UCAN (+36.6 ± 24.9 mg·dL−1, P < 0.0001; +25.2 ± 11.0 μU·mL−1, P < 0.0001), respectively. Fat oxidation was attenuated, and carbohydrate oxidation increased before exercise with G versus PL (−0.06 ± 0.06 g·min−1, P = 0.005; +0.18 ± 0.07 g·min−1, P < 0.0001) and G versus UCAN (−0.06 ± 0.05 g·min−1, P = 0.004; +0.18 ± 0.14 g·min−1, P < 0.0001). However, there were no differences in SCAAT lipolysis at rest or during running at either exercise intensity. Also, there was no effect of treatment on running performance. Conclusions Preexercise carbohydrate lowers fat oxidation and increases carbohydrate oxidation, and these effects are attenuated with low glycemic index carbohydrate. However, these changes are not the result of alterations in SCAAT lipolysis, nor do they affect running performance....

Willingham, BD, Daou, M, VanArsdale, J, Thomas, M, and Saracino, PG. Energy availability in female collegiate beach volleyball athletes. J Strength Cond Res XX(X): 000–000, 2024—Low energy availability (LEA) is a present risk for many female athletes. Yet, the literature on LEA is often reliant on single, short-term, snapshots, which may not be reflective of the chronic energy balance surrounding female athletes in sport. Therefore, the purpose of this study was to establish the current prevalence of LEA in female collegiate beach volleyball athletes during the preseason and across the competitive season. One-way repeated measures analysis of variance was used to compare measures of EA (i.e., dietary intake, activity energy expenditure [EE], body composition) and EE (i.e., resting metabolic rate and thermic effect of feeding) at 4 timepoints—once in the preseason (i.e., Fall), and 3 times across the 10-week competitive season in Spring (i.e., week 1, week 5, and week 9). Significance was set at p ≤ 0.05. Although mean EA was in the subclinical zone (i.e., 30–45 kcal·kg FFM⁻¹·d⁻¹) at each timepoint, the prevalence of LEA for individuals was 30.8% in the preseason, 37.5% at week 1, 25.0% at week 5, and 62.5% at week 9. Further, carbohydrate intake was below the recommended range for power athletes at each timepoint, suggesting that female beach volleyball athletes with LEA may benefit from increasing carbohydrate intake. Despite no statistical differences in body mass across the season (p = 0.577), there was a trend for increasing fat-free mass (p = 0.062) as the season progressed. Importantly, LEA is not a team-wide condition but an individual one. Therefore, approaches to mitigate LEA should be individualized.