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The female athlete triad is a condition where low energy availability is typically observed together with menstrual dysfunction and/or low bone mineral density. How this condition affects maximal work capacity in endurance athletes is not clear, and the recovery time course of menses with increased energy availability with concomitant high training load is unknown. This case study of an amenorrheic elite road cyclist reports resumption of normal menstrual function after weight gain during a 5-year period (2014–2019), while engaged in high training load and competition. The athlete ( $\dot{\mathrm{V}}{\mathrm{O}}_2\text{max}$ 3.54 L/min, 64 ml·min⁻¹·kg⁻¹, aerobic peak power output 300 W, 5.4 W/kg) reported amenorrhea (2013–2015) and oligomenorrhea (2015–2018). Training load increased from 2014 to 2019 (584–818 hr/year and 26,707–41,945 training stress score/year). Regular menses (every 23–35 days) resumed in June 2018, ∼5–6 months after a weight gain episode. During the period of menstrual dysfunction, body mass was 51.3 ± 2.25 kg (mean ± 95% confidence limit) and fat percentage was 19% (dual-energy X-ray absorptiometry, 2016), and after weight gain, body mass was 56.8 ± 2.63 kg and fat percentage was 25% (dual-energy X-ray absorptiometry, 2019). Crank-based power meter data showed absolute mean maximal power (in watts) improvement over the 5 s to 4 hr range through the 2014–2019 period, while relative mean maximal power (in watts per kilogram) likely peaked in the 2015–2016 season for 5 min, 20 min, and 30 min, but remained mostly unchanged across seasons. Results suggest that (a) the best relative power output associated with aerobic capacity (5 min to 1 hr) can be achieved during menstrual dysfunction, (b) high performance achieved despite an increase in body mass, and (c) resumption of menses is achievable while maintaining high training loads when coupled with high energy availability.

Maintaining muscle mass and function during rehabilitation from anterior cruciate ligament injury is complicated by the challenge of accurately prescribing daily energy intakes aligned to energy expenditure. Accordingly, we present a 38-week case study characterizing whole body and regional rates of muscle atrophy and hypertrophy (as inferred by assessments of fat-free mass from dual-energy X-ray absorptiometry) in a professional male soccer player from the English Premier League. In addition, in Week 6, we also quantified energy intake (via the remote food photographic method) and energy expenditure using the doubly labeled water method. Mean daily energy intake (CHO: 1.9–3.2, protein: 1.7–3.3, and fat: 1.4–2.7 g/kg) and energy expenditure were 2,765 ± 474 and 3,178 kcal/day, respectively. In accordance with an apparent energy deficit, total body mass decreased by 1.9 kg during Weeks 1–6 where fat-free mass loss in the injured and noninjured limb was 0.9 and 0.6 kg, respectively, yet, trunk fat-free mass increased by 0.7 kg. In Weeks 7–28, the athlete was advised to increase daily CHO intake (4–6 g/kg) to facilitate an increased daily energy intake. Throughout this period, total body mass increased by 3.6 kg (attributable to a 2.9 and 0.7 kg increase in fat free and fat mass, respectively). Our data suggest it may be advantageous to avoid excessive reductions in energy intake during the initial 6–8 weeks post anterior cruciate ligament surgery so as to limit muscle atrophy.

Sports nutrition is an evolving field, but there is a lack of data on Australian athletes’ knowledge of current sports nutrition guidelines. Additionally, several tools used to assess nutrition knowledge (NK) have not undergone adequate validation. The purpose of this study was to assess and compare the sports NK of elite and nonelite Australian football (AF) athletes using a newly validated questionnaire—The Nutrition for Sport Knowledge Questionnaire. Elite AF players (n = 46) were recruited directly from their club dietitian and nonelite AF players (n = 53) were invited to participate via e-mail from their club president or secretary. The mean NK score of elite and nonelite AF players was 46 ± 16% and 51 ± 11%, respectively (p = .041). In both groups, knowledge of macronutrients, weight management, and alcohol was better than knowledge of supplements, micronutrients, and sports nutrition. Nonelite athletes achieved statistically significantly higher scores on the questionnaire subsections testing weight management (elite: 48 ± 18; nonelite: 57 ± 19, p = .019), micronutrients (elite: 39 ± 19; nonelite: 50 ± 16, p = .004), and alcohol (elite: 52 ± 13; nonelite: 71 ± 17, p = .002). While overall NK of Australian athletes was poor, scores varied greatly among individuals (range: 10–70%) and across the six subsections (topics) being assessed. Professionals working with athletes should undertake an assessment of the athletes’ NK so that they can provide targeted education programs.

We investigated the effects of vitamin D₃ supplementation on physical performance during winter training in vitamin D insufficient taekwondo athletes. Thirty-five collegiate male and female taekwondo athletes, aged 19–22 years with low serum 25(OH)D concentration (28.8 ± 1.10 nmol/L), were randomly assigned to a vitamin D group (n = 20) or a placebo group (n = 15). Subjects received either a vitamin D₃ capsule (5,000 IU/day) or a placebo during 4 weeks of winter training. Blood samples were collected for analyzing serum 25(OH)D concentration. Physical performance tests included Wingate anaerobic test, isokinetic muscle strength and endurance, a countermovement jump test, sit-ups, agility test, and 20-m pacer. Serum 25(OH)D concentrations increased significantly in the vitamin D group (96.0 ± 3.77 nmol/L) after 4 weeks of supplementation, but no changes were found in the placebo group (F = 242.44, p = .000). There were significant interaction effects for anaerobic peak power (F = 7.49, p = .010) and isokinetic knee extension at 180 deg/s (F = 6.08, p = .019). Changes in serum 25(OH)D concentration were positively associated with changes in peak power and isokinetic knee extension at 180 deg/s. However, no significant interaction effects were observed in other performance variables. This study suggests that 4 weeks of vitamin D supplementation elevates serum 25(OH)D concentration to sufficient levels. Correcting vitamin D insufficiency improves some but not all aspects of performance. Thus, efficacy of vitamin D supplementation to enhance performance remains unclear.

Active, as opposed to inactive, individuals are able to adjust their energy intake after preloads of different energy contents. The mechanisms responsible for this remain unknown. This study examined differences in plasma concentration of appetite-related hormones in response to breakfasts of different energy contents, between active and inactive men. Sixteen healthy nonobese (body mass index = 18.5–27 kg/m²) adult males (nine active and seven inactive) participated in this study. Participants were given a high-energy (570 kcal) or a low-energy (205 kcal) breakfast in a random order. Subjective feelings of appetite and plasma concentrations of active ghrelin, active glucagon-like peptide-1, total peptide YY (PYY), cholecystokinin, and insulin were measured in fasting and every 30 min up to 2.5 hr, in response to both breakfasts. Mixed analysis of variance (fat mass [in percentage] as a covariate) revealed a higher concentration of active ghrelin and lower concentration of glucagon-like peptide-1, and cholecystokinin after the low-energy breakfast (p < .001 for all). Postprandial concentration of PYY was greater after the high energy compared with the low energy, but for inactive participants only (p = .014). Active participants had lower postprandial concentrations of insulin than inactive participants (p < .001). Differences in postprandial insulin between breakfasts were significantly lower in active compared with inactive participants (p < .001). Physical activity seems to modulate the postprandial plasma concentration of insulin and PYY after the intake of breakfasts of different energy contents, and that may contribute, at least partially, to the differences in short-term appetite control between active and inactive individuals.

Dietary preworkout supplements are popular among recreational exercisers and athletes. However, the effects of these supplements on the vasculature, both at rest and during exercise, are not well studied. Therefore, the purpose of this study was to determine the effect of 1 week of supplementation with a multi-ingredient dietary preworkout supplement on measures of vascular function at rest and immediately following acute resistance exercise in young, recreationally active adults. Twelve participants (9 males and 3 females; mean ± SD: age = 24.5 ± 3.4 years and body mass index = 24.3 ± 4.7 kg/m²) completed this double-blind, randomized, crossover design study. After familiarization, participants were randomized to either a taste-matched placebo or the preworkout supplement for 1 week preceding the testing visits. Participants underwent measures of vascular function, including brachial artery flow-mediated dilation, measures of central and peripheral blood pressure, and measures of arterial stiffness via pulse wave analysis and pulse wave velocity. All measures were taken at rest and immediately following an acute bilateral leg press exercise session. Resting and postacute exercise flow-mediated dilation, blood pressure, and arterial stiffness were similar between the placebo and the preworkout supplement visits. One week of multi-ingredient preworkout supplementation does not affect vascular function at rest or in response to an acute bout of resistance exercise in young, healthy, recreationally active individuals.

There is a growing interest regarding the effect of exercise on appetite and energy intake in youth. While the role of exercise intensity has been a primary focus of study, the effect of exercise duration on subsequent food intake has not been fully examined in obese adolescents. On three separate mornings in a randomly assigned order, obese adolescent girls (n = 20) aged 12–15 years old were asked to perform a rest session (control, CON) or two cycling sessions for 20 (EX20) or 40 min (EX40) set at their ventilatory threshold. Absolute and relative energy intake were measured from an ad libitum lunch meal 30 min after rest or exercise and appetite feelings assessed using visual analogue scales throughout the day. Hunger, satiety, and prospective food consumption were not significantly different between conditions. Absolute energy intake (kcal) did not differ between conditions, while relative energy intake on EX40 (571 ± 381 kcal) was significantly lower than during CON (702 ± 320 kcal; p < .05) and EX20 (736 ± 457 kcal; p < .05). Fat ingestion (in grams) was significantly lower on CON (7.8 ± 3.2 g) compared with EX20 (10.3 ± 4.6 g; p < .01). Protein intake (in grams) was higher on EX20 (37.0 ± 16.6 g) compared with both CON (29.5 ± 11.7 g; p < .01) and EX40 (33.1 ± 10.9 g; p < .05). However, the percentage of total energy derived from each macronutrient was not different between conditions. Obese adolescent girls do not compensate for an acute bout of exercise set at their ventilatory threshold by increasing energy intake, regardless of the exercise duration.

Novel methods of acute weight loss practiced by combat sport athletes include “water loading,” the consumption of large fluid volumes for several days prior to restriction. We examined claims that this technique increases total body water losses, while also assessing the risk of hyponatremia. Male athletes were separated into control (n = 10) and water loading (n = 11) groups and fed a standardized energy-matched diet for 6 days. Days 1–3 fluid intake was 40 and 100 ml/kg for control and water loading groups, respectively, with both groups consuming 15 ml/kg on Day 4 and following the same rehydration protocol on Days 5 and 6. We tracked body mass (BM), urine sodium, urine specific gravity and volume, training-related sweat losses and blood concentrations of renal hormones, and urea and electrolytes throughout. Physical performance was assessed preintervention and postintervention. Following fluid restriction, there were substantial differences between groups in the ratio of fluid input/output (39%, p < .01, effect size = 1.2) and BM loss (0.6% BM, p = .02, effect size = 0.82). Changes in urine specific gravity, urea and electrolytes, and renal hormones occurred over time (p < .05), with an interaction of time and intervention on blood sodium, potassium, chloride, urea, creatinine, urine specific gravity, and vasopressin (p < .05). Measurements of urea and electrolyte remained within reference ranges, and no differences in physical performance were detected over time or between groups. Water loading appears to be a safe and effective method of acute BM loss under the conditions of this study. Vasopressin-regulated changes in aquaporin channels may potentially partially explain the mechanism of increased body water loss with water loading.

The purpose of this study was to determine whether caffeinated gum influenced performance in a battery of soccer-specific tests used in the assessment of performance in soccer players. In a double-blind, randomized, crossover design, 10 male university-standard soccer players (age: 19 ± 1 years, stature: 1.80 ± 0.10 m, body mass: 75.5 ± 4.8 kg) masticated a caffeinated (200 mg; caffeine) or control (0 mg; placebo) gum on two separate occasions. After a standardized warm-up, gum was chewed for 5 min and subsequently expectorated 5 min before players performed a maximal countermovement jump, a 20-m sprint test, and the Yo-Yo Intermittent Recovery Test Level 1. Performance on 20-m sprints was not different between trials (caffeine: 3.2 ± 0.3 s, placebo: 3.1 ± 0.3 s; p = .567; small effect size: d = 0.33), but caffeine did allow players to cover 2.0% more distance during Yo-Yo Intermittent Recovery Test Level 1 (caffeine: 1,754 ± 156 m, placebo: 1,719 ± 139 m; p = .016; small effect size: d = 0.24) and increase maximal countermovement jump height by 2.2% (caffeine: 47.1 ± 3.4 cm, placebo: 46.1 ± 3.2 cm; p = .008; small effect size: d = 0.30). Performance on selected physical tests (Yo-Yo Intermittent Recovery Test Level 1 and countermovement jump) was improved by the chewing of caffeinated gum in the immediate period before testing in university-standard soccer players, but the sizes of such effects were small. Such findings may have implications for the recommendations made to soccer players about to engage with subsequent exercise performance.

Aspiring female physique athletes are often encouraged to ingest relatively high levels of dietary protein in conjunction with their resistance training programs. However, there is little to no research investigating higher versus lower protein intakes in this population. This study examined the influence of a high versus low-protein diet in conjunction with an 8-week resistance training program in this population. A total of 17 females (21.2 ± 2.1 years; 165.1 ± 5.1 cm; 61 ± 6.1 kg) were randomly assigned to a high-protein diet (HP: 2.5 g·kg⁻¹·day⁻¹; n = 8) or a low-protein diet (LP: 0.9 g·kg⁻¹·day⁻¹, n = 9) and were assessed for body composition and maximal strength prior to and after the 8-week protein intake and exercise intervention. Fat-free mass increased significantly more in the HP group as compared with the LP group (p = .009), going from 47.1 ± 4.5 to 49.2 ± 5.4 kg (+2.1 kg) and from 48.1 ± 2.7 to 48.7 ± 2 kg (+0.6 kg) in the HP and LP groups, respectively. Fat mass significantly decreased over time in the HP group (14.1 ± 3.6 to 13.0 ± 3.3 kg; p < .01), but no change was observed in the LP group (13.2 ± 3.7 to 12.5 ± 3.0 kg). Although maximal strength significantly increased in both groups, there were no differences in strength improvements between the two groups. In aspiring female physique athletes, a higher protein diet is superior to a lower protein diet in terms of increasing fat-free mass in conjunction with a resistance training program.