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Restrictive Eating and Prior Low-Energy Fractures Are Associated With History of Multiple Bone Stress Injuries

Sarah Gehman, Kathryn E. Ackerman, Signe Caksa, Sara E. Rudolph, Julie M. Hughes, Margaret Garrahan, Adam S. Tenforde, Mary L. Bouxsein, and Kristin L. Popp

Bone stress injuries (BSIs) are common among athletes and have high rates of recurrence. However, risk factors for multiple or recurrent BSIs remain understudied. Thus, we aimed to explore whether energy availability, menstrual function, measures of bone health, and a modified Female Athlete Triad Cumulative Risk Assessment (CRA) tool are associated with a history of multiple BSIs. We enrolled 51 female runners (ages 18–36 years) with history of ≤1 BSI (controls; n = 31) or ≥3 BSIs (multiBSI; n = 20) in this cross-sectional study. We measured lumbar spine, total hip, and femoral neck areal bone mineral density by dual-energy X-ray absorptiometry, bone material strength index using impact microindentation, and volumetric bone mineral density, microarchitecture, and estimated strength by high-resolution peripheral quantitative computed tomography. Participants completed questionnaires regarding medical history, low-energy fracture history, and disordered eating attitudes. Compared with controls, multiBSI had greater incidence of prior low-energy fractures (55% vs. 16%, p = .005) and higher modified Triad CRA scores (2.90 ± 2.05 vs. 1.84 ± 1.59, p = .04). Those with multiBSI had higher Eating Disorder Examination Questionnaire (0.92 ± 1.03 vs. 0.46 ± 0.49, p = .04) scores and a greater percentage difference between lowest and highest body mass at their current height (15.5% ± 6.5% vs. 11.5% ± 4.9% p = .02). These preliminary findings indicate that women with a history of multiple BSIs suffered more prior low-energy fractures and have greater historical and current estimates of energy deficit compared with controls. Our results provide strong rationale for future studies to examine whether subclinical indicators of energy deficit contribute to risk for multiple BSIs in female runners.

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Volume 32 (2022): Issue 3 (May 2022)

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Ketone Monoester Ingestion Alters Metabolism and Simulated Rugby Performance in Professional Players

Oliver J. Peacock, Javier T. Gonzalez, Simon P. Roberts, Alan Smith, Scott Drawer, and Keith A. Stokes

Ketone ingestion can alter metabolism but effects on exercise performance are unclear, particularly with regard to the impact on intermittent-intensity exercise and team-sport performance. Nine professional male rugby union players each completed two trials in a double-blind, randomized, crossover design. Participants ingested either 90 ± 9 g carbohydrate (CHO; 9% solution) or an energy matched solution containing 20 ± 2 g CHO (3% solution) and 590 mg/kg body mass β-hydroxybutyrate monoester (CHO + BHB-ME) before and during a simulated rugby union-specific match-play protocol, including repeated high-intensity, sprint and power-based performance tests. Mean time to complete the sustained high-intensity performance tests was reduced by 0.33 ± 0.41 s (2.1%) with CHO + BHB-ME (15.53 ± 0.52 s) compared with CHO (15.86 ± 0.80 s) placebo (p = .04). Mean time to complete the sprint and power-based performance tests were not different between trials. CHO + BHB-ME resulted in blood BHB concentrations that remained >2 mmol/L during exercise (p < .001). Serum lactate and glycerol concentrations were lower after CHO + BHB-ME than CHO (p < .05). Coingestion of a BHB-ME with CHO can alter fuel metabolism (attenuate circulating lactate and glycerol concentrations) and may improve high-intensity running performance during a simulated rugby match-play protocol, without improving shorter duration sprint and power-based efforts.

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Sweating Rate and Sweat Chloride Concentration of Elite Male Basketball Players Measured With a Wearable Microfluidic Device Versus the Standard Absorbent Patch Method

Lindsay B. Baker, Michelle A. King, David M. Keyes, Shyretha D. Brown, Megan D. Engel, Melissa S. Seib, Alexander J. Aranyosi, and Roozbeh Ghaffari

The purpose of this study was to compare a wearable microfluidic device and standard absorbent patch in measuring local sweating rate (LSR) and sweat chloride concentration ([Cl]) in elite basketball players. Participants were 53 male basketball players (25 ± 3 years, 92.2 ± 10.4 kg) in the National Basketball Association’s development league. Players were tested during a moderate-intensity, coach-led practice (98 ± 30 min, 21.0 ± 1.2 °C). From the right ventral forearm, sweat was collected using an absorbent patch (3M Tegaderm + Pad). Subsequently, LSR and local sweat [Cl] were determined via gravimetry and ion chromatography. From the left ventral forearm, LSR and local sweat [Cl] were measured using a wearable microfluidic device and associated smartphone application-based algorithms. Whole-body sweating rate (WBSR) was determined from pre- to postexercise change in body mass corrected for fluid/food intake (ad libitum), urine loss, and estimated respiratory water and metabolic mass loss. The WBSR values predicted by the algorithms in the smartphone application were also recorded. There were no differences between the absorbent patch and microfluidic patch for LSR (1.25 ± 0.91 mg·cm−2·min−1 vs. 1.14 ±0.78 mg·cm−2·min−1, p = .34) or local sweat [Cl] (30.6 ± 17.3 mmol/L vs. 29.6 ± 19.4 mmol/L, p = .55). There was no difference between measured and predicted WBSR (0.97 ± 0.41 L/hr vs. 0.89 ± 0.35 L/hr, p = .22; 95% limits of agreement = 0.61 L/hr). The wearable microfluidic device provides similar LSR, local sweat [Cl], and WBSR results compared with standard field-based methods in elite male basketball players during moderate-intensity practices.

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Nutrition and Physical Activity During British Army Officer Cadet Training: Part 1—Energy Balance and Energy Availability

Victoria C. Edwards, Stephen D. Myers, Sophie L. Wardle, Andrew G. Siddall, Steven D. Powell, Sarah Needham-Beck, Sarah S. Kefyalew, Priya A. Singh, Elise R. Orford, Michelle C. Venables, Sarah Jackson, Julie P. Greeves, and Sam D. Blacker

Military training is characterized by high daily energy expenditures which are difficult to match with energy intake, potentially resulting in negative energy balance (EB) and low energy availability (EA). The aim of this study was to quantify EB and EA during British Army Officer Cadet training. Thirteen (seven women) Officer Cadets (mean ± SD: age 24 ± 3 years) volunteered to participate. EB and EA were estimated from energy intake (weighing of food and food diaries) and energy expenditure (doubly labeled water) measured in three periods of training: 9 days on-camp (CAMP), a 5-day field exercise (FEX), and a 9-day mixture of both CAMP and field-based training (MIX). Variables were compared by condition and gender with a repeated-measures analysis of variance. Negative EB was greatest during FEX (−2,197 ± 455 kcal/day) compared with CAMP (−692 ± 506 kcal/day; p < .001) and MIX (−1,280 ± 309 kcal/day; p < .001). EA was greatest in CAMP (23 ± 10 kcal·kg free-fat mass [FFM]−1·day−1) compared with FEX (1 ± 16 kcal·kg FFM−1·day−1; p = .002) and MIX (10 ± 7 kcal·kg FFM−1·day−1; p = .003), with no apparent difference between FEX and MIX (p = .071). Irrespective of condition, there were no apparent differences between gender in EB (p = .375) or EA (p = .385). These data can be used to inform evidenced-based strategies to manage EA and EB during military training, and enhance the health and performance of military personnel.

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Methodological Considerations for Investigating Iron Status and Regulation in Exercise and Sport Science Studies

Alannah K.A. McKay, Marc Sim, Diego Moretti, Rebecca Hall, Trent Stellingwerff, Richard J. Burden, and Peter Peeling

Iron deficiency is a common health issue in active and athlete populations. Accordingly, research into iron status, regulation, absorption, and iron deficiency treatment strategies is increasing at a rapid rate. However, despite the increase in the quantity of research, various methodological issues need to be addressed as we progress our knowledge in this area. The purpose of this review is to highlight specific considerations for conducting iron-related research in active and athlete populations. First, we discuss the methodological importance of assessment and interpretation of iron status, with reference to blood collection protocols, participant screening procedures, and biomarker selection. Next, we consider numerous variables that should be accounted for in the design of iron-related research studies, such as the iron regulatory hormone hepcidin and its interaction with exercise, in addition to an examination of female physiology and its impact on iron metabolism. Subsequently, we explore dietary iron and nutrient interactions that impact iron regulation and absorption, with recommendations made for optimal methodological control. Consideration is then given to key features of long-term study designs, such as the monitoring of training load, oral iron supplementation, dietary analysis, and general lifestyle factors. Finally, we conclude our recommendations with an exploration of stable iron isotope tracers as a methodology to measure iron absorption. Ultimately, it is our intention that this review can be used as a guide to improve study design, biomarker analysis, and reporting of findings, to maximize the quality of future research outputs in iron-related research focused on active and athlete populations.

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Effect of Different Exercise Training Modalities on Fasting Levels of Oxylipins and Endocannabinoids in Middle-Aged Sedentary Adults: A Randomized Controlled Trial

Lucas Jurado-Fasoli, Wei Yang, Isabelle Kohler, Manuel Dote-Montero, Francisco J. Osuna-Prieto, Xinyu Di, Thomas Hankemeier, Elke H.J. Krekels, Amy C. Harms, Manuel J. Castillo, Francisco J. Amaro-Gahete, and Borja Martinez-Tellez

This study aimed to investigate the effects of different exercise training programs on fasting plasma levels of oxylipins, endocannabinoids (eCBs), and eCBs-like molecules in middle-aged sedentary adults. A 12-week randomized controlled trial was conducted using a parallel group design. Sixty-five middle-aged adults (40–65 years old) were randomly assigned to: (a) no exercise (control group), (b) concurrent training based on international physical activity recommendations (PAR group), (c) high-intensity interval training (HIIT group), and (d) HIIT together with whole-body electromyostimulation (HIIT + EMS group). Plasma levels of oxylipins, eCBs, and eCBs-like molecules were determined in plasma samples before and after the intervention using targeted lipidomics. Body composition was assessed through dual-energy X-ray absorptiometry, and dietary intake through a food frequency questionnaire and three nonconsecutive 24-hr recalls. The physical activity recommendations, HIIT, and HIIT-EMS groups showed decreased plasma levels of omega-6 and omega-3-derived oxylipins, and eCBs and eCBs-like molecules after 12 weeks (all Δ ≤ −0.12; all p < .05). Importantly, after Bonferroni post hoc corrections, the differences in plasma levels of omega-6 and omega-3 oxylipins were not statistically significant compared with the control group (all p > .05). However, after post hoc corrections, plasma levels of anandamide and oleoylethanolamide were increased in the physical activity recommendations group compared with the control group (anandamide: Δ = 0.05 vs. −0.09; oleoylethanolamide: Δ = −0.12 vs. 0.013, all p ≤ .049). In conclusion, this study reports that a 12-week exercise training intervention, independent of the modality applied, does not modify fasting plasma levels of omega-6 and omega-3 oxylipins, eCBs, and eCBs-like molecules in middle-aged sedentary adults.

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Personalized Hydration Requirements of Runners

Samuel N. Cheuvront and Robert W. Kenefick

This study sought to (a) estimate how the duration of running influences sweat losses and contributes to the daily fluid requirement, and (b) empirically estimate the drinking rates required to prevent significant dehydration (≥2% body weight as body water). Individual sweating data and running duration were obtained from male (n = 83) and female (n = 36) runners (n = 146 total observations) performing under highly heterogeneous conditions and over a range of exercise durations (33–280 min). Running <60 min/day increased daily fluid needs by a factor of 1.3, whereas running >60 min/day increased the daily fluid need by a factor of 1.9–2.3. Running <60 min/day generally required no fluid intake to prevent significant dehydration before run completion (31/35 runners). In contrast, running >60 min/day required more than 50% replacement of sweating rates to prevent the same (65/111 runners). Overall sweat losses ranged from ∼0.2 to ∼5.0 L/day, whereas the drinking rates required to prevent significant dehydration ranged from 0 to 1.4 L/hr. The characterization of sweat losses, sweat rate, and required drinking among runners in this study indicate wide individual variability that warrants personalized hydration practices, particularly when running is prolonged (>60 min) and performance is important. This study may serve as a useful guidepost for sports dietitians when planning and communicating fluid needs to athletes, as well as complement guidance related to both personalized programmed and thirst-driven drinking strategies.

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Improved Physiological Markers of Omega-3 Status and Compliance With Omega-3 Supplementation in Division I Track and Field and Cross-Country Athletes: A Randomized Controlled Crossover Trial

Austin J. Graybeal, Brooke Helms, Katie Couris, Daphne Thomas, Tatum Johnston, Victoria Dahan, Nina Escobedo, and Jada L. Willis

A sufficient omega-3 index may enhance cardiovascular function, enhance performance, and decrease inflammation. However, most collegiate athletes are deficient in omega-3s, requiring supplementation. A new type of omega-3 (N3) supplement, Enhanced Recovery™ (ER), claims to improve N3 index while addressing the current issues with traditional supplementation. The purpose of this study was to determine if ER improves N3 status and enhances compliance compared with the current standard in collegiate Division I Track and Field and cross-country athletes during a competitive season. Twenty-five (male = 15 and female = 10) athletes completed this longitudinal, randomized controlled crossover trial. Measurements of N3 status were collected at baseline prior to supplementation, and every 2 weeks for 6 weeks with a 33- to 36-day washout period before crossing over. Supplement compliance and dietary intake of N3 rich foods were collected throughout. Visual analog scales and an exit survey asked questions regarding each treatment. Results showed that N3 index increases within 6 weeks (p < .001) for ER (+37.5%) and control (CON; +55.1%), with small differences between treatments at Weeks 4 (ER = 7.3 ± 1.0; CON = 7.7 ± 1.1; p = .043) and 6 (ER = 7.4 ± 1.2; CON = 7.9 ± 1.2; p = .043). Dietary intake of N3-rich foods and supplement compliance were significant drivers of improvements in N3 status (p < .050). Compliance was not different between treatments but was affected by sex (males = 90.0 ± 17.0% and females = 76.5 ± 21.0%; p = .040), likability (p = .001; r = .77, p < .001), ease (p = .023; r = .53, p = .006), and supplement preference (p = .004), which appeared to favor ER. We conclude that consumption of N3-rich foods and consistent supplementation should be implemented for improvements in N3 status in collegiate athletes, but taste tests/trial periods with ER or CON may help determine preference and improve compliance.

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A Short-Term Low-Fiber Diet Reduces Body Mass in Healthy Young Men: Implications for Weight-Sensitive Sports

Wee Lun Foo, Jake D. Harrison, Frank T. Mhizha, Carl Langan-Evans, James P. Morton, Jamie N. Pugh, and Jose L. Areta

Athletes from weight-sensitive sports are reported to consume low-fiber diets (LOW) to induce acute reductions in body mass (BM). However, evidence supporting their efficacy is anecdotal. Therefore, we aimed to determine the effect of a LOW on acute changes in BM. Nineteen healthy males (32 ± 10 years, 1.79 ± 0.07 m, 77.5 ± 8.1 kg) consumed their habitual diet (∼30 g fiber/day) for 7 consecutive days followed by 4 days of a LOW (<10 g fiber/day) that was matched for energy and macronutrient content. Participants also matched their daily exercise load during LOW to that completed during habitual diet (p = .669, average 257 ± 141 arbitrary units). BM was significantly reduced in LOW versus habitual diet after 4 days (Δ = 0.40 ± 0.77 kg or 0.49% ± 0.91%, p < .05, effect size [ES] [95% confidence interval] = −0.53 [−1.17, 0.12]) and on the morning of Day 5 (Δ = 0.58 ± 0.83 kg or 0.74% ± 0.99%, p < .01, ES = −0.69 [−1.34, −0.03]). LOW resulted in moderately higher hunger (Δ = 5 ± 9 mm, p = .015, ES = 0.55 [−0.09, 1.20]), a decline in stool frequency from 2 ± 0 to 1 ± 0 bowel movements per day (p = .012, ES = 0.64 [−0.02, 1.29]) and stool softness decrease (p = .005). Nonetheless, participants reported the diet to be tolerable (n = 18/19) and were willing to repeat it (n = 16/19). Data demonstrate for the first time that consumption of a short-term LOW induces reductions in BM.