Molecular responses to acute exercise and their relevance for adaptations in skeletal muscle to exercise training.

Repeated, episodic bouts of skeletal muscle contraction undertaken frequently as structured exercise training are a potent stimulus for physiological adaptation in many organs. Specifically, in skeletal muscle, remarkable plasticity is demonstrated by the remodeling of muscle structure and function in terms of muscular size, force, endurance, and contractile velocity as a result of the functional demands induced by various types of exercise training. This plasticity, and the mechanistic basis for adaptations to skeletal muscle in response to exercise training, are underpinned by activation and/or repression of molecular pathways and processes in response to each individual acute exercise session. These pathways include the transduction of signals arising from neuronal, mechanical, metabolic, and hormonal stimuli through complex signal transduction networks, which are linked to a myriad of effector proteins involved in the regulation of pre- and posttranscriptional processes, and protein translation and degradation processes. This review therefore describes acute exercise-induced signal transduction and the molecular responses to acute exercise in skeletal muscle including emerging concepts such as epigenetic pre- and posttranscriptional regulation and the regulation of protein translation and degradation. A critical appraisal of methodological approaches and the current state of knowledge informs a series of recommendations offered as future directions in the field.

Test-Retest Reliability of Running Economy and Metabolic and Cardiorespiratory Parameters During a Multistage Incremental Treadmill Test in Male Middle- and Long-Distance Runners.

This study investigated the test-retest reliability of running economy (RE) and metabolic and cardiorespiratory parameters related to endurance running performance using a multistage incremental treadmill test. On two occasions separated by 21-28 days, 12 male middle- and long-distance runners ran at 10, 11, 12, 13, and 14 km/hr for 8 min each stage, immediately followed by a ramp test to volitional exhaustion. Carbohydrate (10% maltodextrin solution) was consumed before and during the test to provide ∼1 g/min of exercise. RE, minute ventilation (V˙E), oxygen consumption (V˙O2), carbon dioxide production (V˙CO2), respiratory exchange ratio (RER), heart rate (HR), ratings of perceived exertion (RPE), and blood glucose and lactate concentrations were recorded for each stage and at volitional exhaustion. Time-to-exhaustion (TTE) and peak oxygen consumption (V˙O2peak) during the ramp test were also recorded. Absolute reliability, calculated as the coefficient of variation (CV) between repeated measures, ranged from 2.3% to 3.1% for RE, whereas relative reliability, calculated as the intraclass correlation coefficient (ICC), ranged from .42 to .79. V˙E, V˙O2, V˙O2peak, V˙CO2, RER, and HR had a CV of 1.1%-4.3% across all stages. TTE and RPE had a CV of 7.2% and 2.3%-10.8%, respectively, while glucose and lactate had a CV of 4.0%-17.8%. All other parameters, except for blood glucose, were demonstrated to have good-to-excellent relative reliability assessed by ICC. Measures of RE, V˙O2peak, and TTE were reliable during this two-phase multistage incremental treadmill test in a cohort of trained and highly trained male middle- and long-distance runners.

The separation and identification of circulating small extracellular vesicles from endurance-trained, strength-trained and recreationally active men.

Small extracellular vesicles (EV) are membrane-encapsulated particles that carry bioactive cargoes, are released by all cell types and are present in all human biofluids. Changes in EV profiles and abundance occur in response to acute exercise, but this study investigated whether individuals with divergent histories of exercise training (recreationally active controls - CON; endurance-trained - END; strength-trained - STR) presented with varied abundances of small EVs in resting samples and whether the abundance of small EVs differed within each group across two measurement days. Participants (n = 38, all male; CON n = 12, END n = 13, STR n = 13) arrived at the lab on two separate occasions in a rested, overnight fasted state, with standardisation of time of day of sampling, recent dietary intake, time since last meal and time since last exercise training session (∼40 h). Whole blood samples were collected and separated into plasma from which small EVs were separated using size exclusion chromatography and identified in accordance with the Minimal Information For Studies of Extracellular Vesicles (MISEV) guidelines. No differences in the abundance of small EVs were observed within or between groups across multiple methods of small EV identification (nanoparticle tracking analysis, flow cytometry, immunoblot of specific EV markers). Targeted metabolomics of the small EV preparations identified 96 metabolites that were associated with the structure and function of small EVs, with no statistically significant differences in concentrations observed across groups. The results of the current study suggest that the abundance and metabolomic profile of small EVs derived from men with divergent histories of exercise training are similar to those in resting blood samples. KEY POINTS: Extracellular vesicles (EV) are membrane-encapsulated particles that are present in circulation and carry bioactive materials as 'cargo'. The abundance and profile of small EVs are responsive to acute exercise, but little is known about the relationship between small EVs and exercise training. This study examined the abundance, and a targeted metabolomic profile, of small EVs separated from the blood of endurance athletes, strength athletes and recreationally active controls at rest (∼40 h after the most recent exercise session) on two separate but identical lab visits. No differences were observed in the abundance or metabolomic profile of small EV preparations between the groups or between the lab visits within each group. Further research should determine whether the bioactive cargoes (e.g. RNA, protein and additional metabolites) carried within EVs are altered in individuals with divergent histories of exercise training or in response to exercise training interventions.

Functional assays reflective of cancer hallmarks in BT-549 cells are not impacted by media supplemented with exercise-trained plasma.

NEW FINDINGS: What is the central question of this study? Little is known regarding the effects of media supplemented with resting plasma from exercise-trained individuals, despite the established bioactive effects of acutely exercised samples. Does media supplemented with resting plasma from endurance-trained, strength-trained or recreationally active controls impact hallmarks of cancer in BT-549 cells? What is the main finding and its importance? Supplementing media with plasma from these trained athletes did not impact proliferation, migration, invasion or anoikis resistance compared to plasma from recreationally-active controls. These findings suggest that 'anti-cancer' effects of exercise are not present in resting blood samples of exercise-trained individuals. ABSTRACT: Media supplemented with sera from acutely exercised men has been shown to have 'anti-cancer' effects on prostate and breast cancer cell lines. This study investigated whether media supplemented with plasma samples taken at rest (≥30 h since the most recent exercise session) from men who were endurance-trained (END), strength-trained (STR) or recreationally active controls (CON) impacted the results of four assays that mimic hallmarks of cancer (proliferation, migration, extracellular matrix invasion and anoikis resistance) in the BT-549 breast cancer cell line. Compared to control conditions of either serum-free media or fetal bovine serum as appropriate, BT-549 cells cultured with plasma-supplemented media regardless of group resulted in greater cell proliferation (∼20-50%) and cell migration (∼15-20%), and lower extracellular matrix invasion (∼10-20%) and anoikis resistance (∼15-20%). Supplementing media with plasma from END or STR did not impact any outcomes of these assays compared to plasma from CON. Media supplemented with human plasma can impact functional assays reflective of cancer hallmarks in BT-549 cells, but effects of exercise on proliferation, migration, extracellular matrix invasion and anoikis resistance were not evident in resting blood samples of individuals with a prior history of exercise training.

The resting serum metabolome in response to short-term sprint interval training.

PURPOSE: To investigate the response of a targeted fraction of (168 metabolites) of the resting serum metabolome to 9 sessions of sprint interval training (SIT). METHODS: Thirty-four recreationally active males provided resting blood samples before (baseline) and 48-72 h after (post) a short-term (9 sessions) cycle ergometer-based SIT intervention. A targeted analysis of 168 metabolites was performed on serum using liquid chromatography mass spectrometry (LC-MS). 160 distinct metabolites were identified and combined with 4 calculated metabolite sums and 3 calculated metabolite ratios creating a panel of 167 individual factors. Data were analysed using principal component analysis and univariate testing of all factors classified into 5 metabolite subgroups. RESULTS: SIT improved anaerobic capacity measured by average power output during a Wingate test (p < 0.01; mean difference = 38 W, 95% confidence interval [26, 51]) and aerobic capacity measured by average power output in a 20 min cycling test (p < 0.01; 17 W [12, 23]). Limited separation was discernible in the targeted serum metabolome between baseline and post-intervention when projected on the first and second principal component(s). However, univariate testing identified 11 fatty acids that had lower concentrations (false discovery rate < 0.05) in post-intervention samples. CONCLUSIONS: These findings demonstrate that this short-term SIT intervention had limited effect on the serum metabolome at rest, but a subfraction of fatty acids are potentially sensitive to short-term exercise training.

Prevalence and determinants of sarcopenia in community-dwelling older adults in Ireland.

BACKGROUND: Data on the prevalence of sarcopenia among older adults in Ireland are lacking. AIMS: To assess the prevalence and determinants of sarcopenia among community-dwelling older adults in Ireland. METHODS: This cross-sectional analysis involved n = 308 community-dwelling adults aged ≥ 65 y living in Ireland. Participants were recruited via recreational clubs and primary healthcare services. Sarcopenia was defined according to the 2019 European Working Group on Sarcopenia in Older People (EWGSOP2) criteria. Skeletal muscle mass was estimated using bioelectrical impedance analysis, strength was measured via handgrip dynamometry, and physical performance was assessed using the Short Physical Performance Battery. Detailed information was collected on demographics, health, and lifestyle. Dietary macronutrient intake was measured via a single 24 h recall. Binary logistic regression was used to examine potential demographic, health, lifestyle, and dietary determinants of sarcopenia (where both probable and confirmed sarcopenia were combined). RESULTS: The prevalence of EWGSOP2-defined probable sarcopenia was 20.8% and confirmed sarcopenia was 8.1% (5.8% had severe sarcopenia). Polypharmacy (OR 2.60, 95% confidence interval [CI] 1.3, 5.23), height (OR 0.95, 95% CI 0.91, 0.98), and Instrumental Activities Of Daily Living (IADL) score (OR 0.71, 95% CI 0.59, 0.86) were independently associated with sarcopenia (probable and confirmed combined). There were no independent associations between energy-adjusted macronutrient intakes, as determined by 24 h recall, and sarcopenia. CONCLUSION: Sarcopenia prevalence within this sample of community-dwelling older adults in Ireland is broadly similar to other European cohorts. Polypharmacy, lower height, and lower IADL score were independently associated with EWGSOP2-defined sarcopenia.

Within-Subject Variability and the Influence of Exercise Training History on the Resting Plasma Metabolome in Men.

This study investigated within-subject variability in the circulating metabolome under controlled conditions, and whether divergent exercise training backgrounds were associated with alterations in the circulating metabolome assessed in resting samples. Thirty-seven men comprising of endurance athletes (END; body mass, 71.0 ± 6.8 kg; fat-free mass index, 16.9 ± 1.1 kg/m2), strength athletes (STR; 94.5 ± 8.8 kg; 23.0 ± 1.8 kg/m2), and recreationally active controls (CON; 77.6 ± 7.7 kg; 18.1 ± 1.0 kg/m2) provided blood samples after an overnight fast on two separate occasions controlled for time of day of sampling, recent dietary intake, time since last meal, and time since last exercise training session. A targeted profile of metabolites, performed using liquid chromatography and mass spectrometry on plasma samples, identified 166 individual metabolites and metabolite features, which were analyzed with intraclass correlation coefficients, a multilevel principal component analysis, and univariate t tests adjusted for multiple comparisons. The median intraclass correlation coefficient was .49, with 46 metabolites displaying good reliability and 31 metabolites displaying excellent reliability. No difference in the abundance of any individual metabolite was identified within groups when compared between visits, but a combined total of 44 metabolites were significantly different (false discovery rate <0.05) between groups (END vs. CON, 42 metabolites; STR vs. CON, 10 metabolites; and END vs. STR, five metabolites). Under similar measurement conditions, the reliability of resting plasma metabolite concentrations varies largely at the level of individual metabolites with ∼48% of metabolites displaying good-to-excellent reliability. However, a history of exercise training was associated with alterations in the abundance of ∼28% of metabolites in the targeted profile employed in this study.

The Priming Effect of a Heavy or Very Heavy Resisted Sled Sprint-Based Conditioning Activity on Subsequent Unresisted Sprint Performance in Team Field Sport Athletes.

ABSTRACT: Monahan, M and Egan, B. The priming effect of a heavy or very heavy resisted sled sprint-based conditioning activity on subsequent unresisted sprint performance in team field sport athletes. J Strength Cond Res 37(1): 91-97, 2023-The effect of resisted sled sprinting (RSS) on postactivation performance enhancement (PAPE) was investigated in team field sport athletes (n = 28; m and female, 15 and 13; age, 22.1 ± 2.5 years; height, 1.77 ± 0.11 m; body mass [BM], 75.1 ± 16.4 kg). After a standardized warm-up, unresisted sprint (URS) performance was measured over 10- and 20-m (PRE) followed by a conditioning activity (CA) consisting of 3 × 20 m RSS. Unresisted sprint performance was then measured again at 30 seconds and 4, 8, 12, 16, 20, and 24 minutes after CA. The effect of heavy (H-RSS) or very heavy (VH-RSS) sled loads were compared during 2 separate visits using a randomized crossover design. Heavy-resisted sled sprinting and VH-RSS loads corresponded to a velocity decrement (Vdec) of 17.3 ± 3.6%Vdec (20.0 ± 2.3%BM) and 52.9 ± 3.8%Vdec (64.3 ± 7.0%BM), respectively. Unresisted sprint performance after CA was slower than PRE over 10- and 20-m (both p < 0.001 for time). The decline in URS performance over 20-m was greater in VH-RSS (time × sled load interaction, p = 0.033). However, after extraction of the fastest sprint times after CA, the fastest sprint time for 10-m improved after H-RSS by 0.026 (0.001, 0.050) seconds (p = 0.040; d = 0.21) but not after VH-RSS (p = 0.054; d = 0.14). The fastest sprint times for 20-m were similar to PRE after H-RSS and VH-RSS. No sex-specific differences were observed. Given the high intersubject variability in the magnitude of improvement, and for the time point at which the fastest sprint occurred, there remains questionable practical value to an RSS-based CA as a means to induce a PAPE for URS performance.

Dietary Intakes and the Risk of Low Energy Availability in Male and Female Advanced and Elite Rock Climbers.

ABSTRACT: Monedero, J, Duff, C, and Egan, B. Dietary intakes and the risk of low energy availability in male and female advanced and elite rock climbers. J Strength Cond Res 37(3): e8-e15, 2023-There is a culture among rock climbers of striving to maintain low body mass and percentage body fat to enhance performance. Diet practices based on this belief might lead to increased risk of low energy availability (LEA) or eating disorders (EDs). Twenty-five advanced or elite rock climbers (male, n = 14; female, n = 11) had body composition measured, completed 4-day food intake and physical activity diaries while wearing an accelerometer and heart rate monitor, and completed the Eating Attitudes Test (EAT)-26 and the Low Energy Availability in Females Questionnaire (LEAF-Q; n = 11 female subjects only). EAT-26 scores of 3.5 (1.8, 7.0) [median (IQR)] and 9.3 ± 6.4 (mean ± SD ) for male and female subjects, respectively, indicated low risk of ED in this cohort, but 4 female subjects were at high risk of LEA according to LEAF-Q scores. Suboptimal (<45 kcal·kg·FFM -1 ·d -1 ) and LEA (<30 kcal·kg·FFM -1 ·d -1 ) were evident in 88 and 28%, respectively, of climbers. However, only the female climbers had energy intakes (1775 ± 351 kcal·d -1 ) significantly lower than their calculated energy requirements (2056 ± 254 kcal·d -1 ; p = 0.006). In all subjects, carbohydrate intakes were lower (male subjects: 3.8 ± 1.2 g·kg -1 ·d -1 , p = 0.002; female subjects: 3.4 ± 0.7 g·kg -1 ·d -1 , p < 0.001), and fat intakes were higher (male subjects: 1.6 ± 0.5 g·kg -1 ·d -1 , p < 0.001; female subjects: 1.4 ± 0.4 g·kg -1 ·day -1 , p < 0.001) than current sports nutrition recommendations, and inadequate intakes of calcium, magnesium, and vitamin D were observed. Female subjects specifically had lower than recommended intakes of protein and iron. These results show that advanced and elite rock climbers have a high prevalence of LEA and have a risk of having nutritional deficiencies as result of their diet.

Effect of rapid weight loss incorporating hot salt water immersion on changes in body mass, blood markers, and indices of performance in male mixed martial arts athletes.

PURPOSE: To investigate the effects of rapid weight loss (RWL), incorporating comparison of hot water immersion (HWI) in fresh or salt water, on changes in body mass, blood markers, and indices of performance in mixed martial arts athletes. METHODS: In a crossover design comparing fresh water (FWB) to salt water (SWB; 5.0%wt/vol Epsom salt) bathing, 13 males performed 20 min of HWI (~ 40.3 °C) followed by 40 min wrapped in a heated blanket, twice in sequence (2 h total). Before bathing, ~ 26 to ~ 28 h of fluid and dietary restriction was undertaken, and ~ 24 to ~ 26 h of a high carbohydrate diet and rehydration was undertaken as recovery. RESULTS: During the entire RWL process, participants lost ~ 5.3% body mass. Body mass lost during the 2 h hot bath protocol was 2.17 ± 0.81 kg (~ 2.7% body mass) and 2.24 ± 0.64 kg (~ 2.8% body mass) for FWB and SWB, respectively (P = 0.647 between trials). Blood urea nitrogen, creatinine, sodium, chloride, hemoglobin, and hematocrit were increased (all P < 0.05), and plasma volume was decreased (~ 14%; P < 0.01), but did not differ between FWB and SWB, and were similar to baseline values after recovery. No indices of performance (e.g., countermovement jump, isometric strength, and functional threshold power) were impacted when RWL was followed by the recovery process. CONCLUSION: Under the conditions of this hot bath protocol, fluid loss was not augmented by the addition of ~ 5.0%wt/vol of Epsom salt during HWI, and RWL of ~ 5.3% body mass followed by > 24 h of recovery did not impact indices of performance.

Increases in protein intake, protein distribution score, and micronutrient intakes in older adults in response to a whole food-based dietary intervention.

BACKGROUND: Changes in nutrient intakes and protein distribution were analyzed in response to a whole food-based dietary intervention targeting high-protein meals in older adults. METHODS: Community-dwelling older adults (n = 56; M/F, 28/28; age, 69.3 ± 4.0 years) completed a 12-week intervention after randomization to exercise only (EX, n = 19), nutrition only (NUTR, n = 16), or nutrition plus exercise (NUTR + EX, n = 21). NUTR and NUTR + EX followed a dietary intervention targeting ~ 0.4 g/kg of protein at each of breakfast, lunch and dinner. RESULTS: Relative protein intake increased in NUTR (0.99 ± 0.34 to 1.43 ± 0.39 g/kg, P < 0.001) and NUTR + EX (0.90 ± 0.20 to 1.57 ± 0.49 g/kg, P < 0.001). Intakes of cholesterol, B vitamins, selenium and iodine were increased in both NUTR and NUTR + EX (P < 0.05 for all). CONCLUSION: This dietary intervention was effective at increasing daily protein intake and achieving an even distribution pattern. Changes in micronutrient intake were marked, and reflect the increase in consumption of animal-derived protein-rich food sources.

Self-Reported Prevalence, Magnitude, and Methods of Rapid Weight Loss in Male and Female Competitive Powerlifters.

ABSTRACT: Nolan, D, Lynch, AE, and Egan, B. Self-reported prevalence, magnitude, and methods of rapid weight loss in male and female competitive powerlifters. J Strength Cond Res 36(2): 405-410, 2022-Rapid weight loss (RWL) is common practice in weight category sports, but no empirical data exist documenting the weight-making practices of competitive strength athletes. This study investigated the self-reported prevalence, magnitude, and methods of RWL used by male and female powerlifters when preparing for competition. Competitive powerlifters (n = 321; M/F, 194/127) completed an anonymous online questionnaire previously validated for assessment of methods of RWL. Respondents were categorized by their federation's respective antidoping policy, weigh-in procedure, and degree of assistive equipment allowed, in addition to their use or not of RWL. Subgroup analyses were performed on the largest category of respondents (n = 200, M/F, 117/83; ≤2-hour weigh-in, drug-tested, "raw") based on sex, weight category, and competitive status. Prevalence of RWL was 85.8%, with an average RWL of 3.0 ± 1.9% body mass and an RWL score of 25.1 ± 7.4. Neither sex nor weight category influenced the RWL score, but in male athletes, a lower RWL score (22.7 ± 6.3) was reported in athletes in the lowest tertile of the Wilks score (p = 0.015). Frequencies of "always use" were reported as 54.0% for fluid restriction and 49.0% for water loading. Coaches (37.5%) and online resources (35.0%) were "very influential" on RWL practices in these athletes, while doctors (85.5%) and dieticians (63.0%) were reported to be "not influential." The prevalence of RWL is high in competitive powerlifting, and the methods used are akin to other weight category sports, but the reported RWL scores are lower than reported in combat sports with longer recovery periods after weigh-in.

Physiological and Perceptual Responses to a Single Session of Resisted Sled Sprint Training at Light or Heavy Sled Loads.

ABSTRACT: Monahan, M, Petrakos, G, and Egan, B. Physiological and perceptual responses to a single session of resisted sled sprint training at light or heavy sled loads. J Strength Cond Res 36(10): 2733-2740, 2022-The acute physiological and perceptual responses to a single session of resisted sled sprint (RSS) training are largely unexplored, nor have differences, if any, between male and female athletes been compared. Team field sport athletes (n = 27; male/female, 15/12; 21.1 ± 2.7 years) were assessed for Maximal Resisted Sled Load (MRSL) from which light (L-RSS, 30%MRSL) and heavy (H-RSS, 80%MRSL) sled loads were prescribed. On separate occasions in random order, 2 training sessions of 12 × 20 m RSS repetitions at either L- or H-RSS were performed, and assessments of physiological and perceptual responses were performed before (PRE), during, after (POST) and 24 hours after (+24 hours POST) each session. Compared to unresisted sprints, velocity decrements of 7.5 ± 2.2 and 22.7 ± 8.1% were produced by L-RSS and H-RSS, respectively. Heart rate, blood lactate, and ratings of perceived exertion were higher in H-RSS compared to L-RSS. Decrements in 20 m sprint and countermovement jump performance observed at POST had returned to PRE values at +24 hours POST. Except for a higher heart rate (∼7-12 b·min-1) in females during the respective sessions, responses to L- and H-RSS were generally similar between males and females. A single session of heavy RSS training is more demanding than light RSS training when matched for sprint number and distance, but measures of lower limb power and sprint performance return to pre-training levels within 24 hours regardless of sled load. Males and females respond similarly to a single session of RSS training when individualized, relative intensity sled loads are prescribed.

No Effect of a Ketone Monoester on Markers of Stress and Performance in a Live-Burn Search and Rescue in Firefighters.

ABSTRACT: Waldman, HS, Bryant, AR, Shepherd, BD, Egan, B, and McAllister, MJ. No effect of a ketone monoester on markers of stress and performance in a live-burn search and rescue in firefighters. J Strength Cond Res 36(3): 763-771, 2022-Firefighters experience a range of stressors that impair performance and elevate the risk for developing cardiometabolic diseases. ß-Hydroxybutyrate (ßHB) has been shown to mitigate markers of oxidative stress and inflammation and serve as an alternative fuel with implications to physical performance. On 2 occasions in a double-blind, counterbalanced, and crossover design, 14 professional firefighters performed a live-burn, search and rescue (S&R) 30 minutes after ingestion of a ketone monoester (KME; 0.5 g·kg-1) or a placebo (PLA). Dependent variables collected before and after the S&R included salivary markers of stress and inflammation (cortisol, α-amylase, interleukin-1 beta, uric acid), perceptual markers (profile of mood state [POMS]), gastrointestinal distress (GI), rating of perceived exertion [RPE]), time to completion, and capillary blood measurement of ßHB and glucose. KME resulted in capillary ßHB concentrations of approximately 2.1-3.2 mM throughout the protocol. Capillary glucose concentrations were lower for the KME compared with PLA (∼7%) (interaction effect, p < 0.001). Salivary markers of stress, GI, and time to complete the S&R (∼10 minutes) did not differ between trials, although KME ingestion resulted in significantly higher RPE after the live-burn S&R (KME,6 ± 1; PLA, 4 ± 1). However, POMS data showed the KME also lowered subjective states of nervousness (KME, 0.0 ± 0.0; PLA, 0.6 ± 0.8) and anxiety (KME, 0.0 ± 0.0; PLA, 0.6 ± 0.7) before the S&R (all p < 0.05; large effect sizes). Compared with PLA, ingestion of a KME by firefighters did not mitigate the rise in various markers of salivary stress or impact physical performance during a live-burn S&R. However, differences in RPE and POMS variables were observed, suggesting a possible cognitive role for ßHB.

Comparison of hot water immersion at self-adjusted maximum tolerable temperature, with or without the addition of salt, for rapid weight loss in mixed martial arts athletes.

Hot water immersion is used by athletes in weight category sports to produce rapid weight loss (RWL) by means of passive fluid loss, and often is performed with the addition of Epsom salts (magnesium sulphate). This study investigated the magnitude of body mass losses during hot water immersion with or without the addition of salt, with the temperature commencing at 37.8°C and being self-adjusted by participants to their maximum tolerable temperature. In a crossover design, eight male MMA athletes (29.4 ± 5.3 y; 1.83 ± 0.05 m; 85.0 ± 4.9 kg) performed a 20 min whole-body immersion followed by a 40 min wrap in a warm room, twice in sequence per visit. During one visit, only fresh water was used (FWB), and in the other visit, magnesium sulphate (1.6% wt/vol) was added to the bath (SWB). Prior to each visit, 24 h of carbohydrate, fibre and fluid restriction was undertaken. Water temperatures at the end of the first and second baths were ~39.0°C and ~39.5°C, respectively. Body mass losses induced by the hot bath protocols were 1.71 ± 0.70 kg and 1.66 ± 0.78 kg for FWB and SWB, respectively (P = 0.867 between trials, d = 0.07), and equivalent to ~2.0% body mass. Body mass lost during the entire RWL protocol was 4.5 ± 0.7%. Under the conditions employed, the magnitude of body mass lost in SWB was similar to FWB. Augmenting passive fluid loss during hot water immersion with the addition of salt may require a higher salt concentration than that presently utilised.

Changes in body composition and substrate utilization after a short-term ketogenic diet in endurance-trained males.

Few studies have investigated the short-term effects of a very low carbohydrate ketogenic diet (KD) on body composition and substrate utilization in trained individuals. This study investigated effects on substrate utilization during incremental exercise, and changes in body composition, in response to seven days ad libitum consumption of a KD by athletes from endurance sports. Nine young trained males (age, 21.8 ± 1.9 y; height, 1.83 ± 0.11 m; body mass, 78.4 ± 13.8 kg; body fat, 14.9 ± 3.9%; VO2peak, 54.3 ± 5.9 mL kg-1 min-1) were assessed before (day 0; PRE) and after (day 7; POST) seven days of consuming an ad libitum KD. Following an overnight fast, body composition was measured by dual x-ray absorptiometry, and substrate utilization was measured during an incremental (3 min stages, 35 W increments) exercise test on a cycle ergometer. After KD, Wmax (PRE, 295 ± 30 W; POST, 292 ± 38 W) and VO2peak (PRE, 4.18 ± 0.33 L min-1; POST, 4.10 ± 0.43 L min-1) were unchanged, whereas body mass [-2.4 (-3.2, -1.6) kg; P < 0.001, d = 0.21], fat mass [-0.78 (-1.10, -0.46) kg; P < 0.001, d = 0.22] and fat-free mass (FFM) [-1.82 (-3.12, -0.51) kg; P = 0.013, d = 0.22] all decreased. The respiratory exchange ratio was lower, and rates of fat oxidation were higher, at POST across a range of exercise intensities. Maximal fat oxidation rate was ~1.8-fold higher after KD (PRE, 0.54 ± 0.13 g min-1; POST, 0.95 ± 0.24 g min-1; P < 0.001, d = 2.2). Short-term KD results in loss of both fat mass and FFM, increased rates of fat oxidation and a concomitant reduction in CHO utilization even at moderate-to-high intensities of exercise.

The interaction between maternal smoking, illicit drug use and alcohol consumption associated with neonatal outcomes.

BACKGROUND: The adverse effects of smoking on neonatal outcomes, such as small-for-gestational-age (SGA), has been extensively studied however, the consequences of smoking combined with alcohol and/or drug use is less clear. METHODS: This retrospective observational study analyzed clinical and sociodemographic details of 40156 women who delivered a singleton baby between the years 2011 and 2015. RESULTS: Compared with women who had never smoked, smokers who did not engage in alcohol or drug use had an odds ratio (OR) of delivering a baby who was SGA of 3.2 (95% CI: 3.1-3.5). Smokers who used illicit drugs in isolation or in combination with alcohol during pregnancy had higher ORs for SGA (1.4, 95% CI: 1.1-1.7, P = 0.006 and 1.8, 95% CI: 1.2-2.7, P = 0.007) compared to women who smoked but did not engage in alcohol or drug use in pregnancy. These women also delivered babies with lower mean birthweights (125 g, P < 0.001 and 181.4 g, P = 0.003) and head circumferences (0.4 cm, P < 0.001 and 0.3 cm, P = 0.048). Women who smoked and used alcohol, but not illicit drugs were not associated adverse outcomes above that of smoking in isolation. CONCLUSION: Illicit drug use combined with maternal smoking during pregnancy increases the risk of adverse neonatal outcomes above that of smoking in isolation.

Comparison of hot water immersion at 37.8°C with or without salt for rapid weight loss in mixed martial arts athletes.

Hot water immersion, known as a hot bath, is used by MMA athletes to produce rapid weight loss (RWL) by means of passive fluid loss. This study investigated the magnitude of body mass losses using a standardized hot bath protocol with or without the addition of salt. In a crossover design, eleven male MMA athletes (28.5 ± 4.6 y; 1.83 ± 0.07 m; 82.5 ± 9.1 kg) performed a 20-min immersion at 37.8°C followed by a 40-min wrap in a warm room. This bath and wrap was performed twice per visit. During one visit, only fresh water was used (FWB), and in the other visit, magnesium sulphate (1.6% wt/vol) was added to the bath (SWB). Prior to each visit, 24 h of carbohydrate, fibre, and fluid restriction was undertaken as part of the RWL protocol. Body mass losses induced by the hot bath protocols were 1.63 ± 0.75 kg and 1.60 ± 0.80 kg for FWB and SWB, respectively, and equivalent to ~2.1% body mass. Under the conditions employed, the magnitude of body mass loss in SWB was similar to FWB. However, further research should explore bathing in a temperature that is consistent with that habitually used by fighters, and/or higher concentrations of salt.

Acute ingestion of beetroot juice does not improve short-duration repeated sprint running performance in male team sport athletes.

The effects of acute ingestion of nitrate on short-duration repeated sprint performance (RSP) are unclear. This study investigated the effect of acute ingestion of beetroot juice on a test of RSP in team sport athletes. Sixteen male team sport athletes undertook four trials using a 40 m maximum shuttle run test (MST), which incorporates 10 × 40 m shuttle sprints with 30 s between the start of each sprint. Two familiarisation trials, followed by nitrate-rich beetroot juice (BR; ~6 mmol nitrate) and nitrate-depleted beetroot juice (PLA; ~0.0034 mmol nitrate) trials were completed in a randomised, double-blind manner. Ingestion of beetroot juice 3 h prior to exercise elevated plasma nitrate concentrations ~6-fold in BR (BR, 413 ± 56 µM; PLA, 69 ± 30 µM; P < 0.001). RSP, assessed by sprint performance decrement (Sdec; %), did not differ (P = 0.337) between BR (5.31 ± 2.49%) and PLA (5.71 ± 2.61%). There was no difference between trials for total sprint time (P = 0.806), fastest sprint (P = 0.341), slowest sprint (P = 0.787), or post-exercise blood lactate concentration (BR, 11.8 ± 2.5 mM; PLA, 12.2 ± 2.3 mM; P = 0.109). Therefore, acute ingestion of beetroot juice did not improve a test of short-duration RSP in team sport athletes.

Exogenous Ketone Salts Do Not Improve Cognitive Performance During a Dual-Stress Challenge.

In the present study, our team aimed to investigate the effects of acute ingestion of a ketone salt (KS) supplement on the cognitive performance in healthy college-aged males during a dual-stress challenge (DSC). Following a peak oxygen uptake test and DSC familiarization, 16 males completed a DSC while cycling at 60% of their respective peak oxygen uptake after ingesting either a commercially available racemic (D- and L-)ß-hydroxybutyrate (ß-OHB) KS (0.38 g/kg body mass) or a placebo, using a triple-blinded, crossover, and counterbalanced design. The participants consumed the KS or placebo at -60 and -15 min prior to the start of the DSC. Heart rate, rating of perceived exertion, and blood ß-OHB and glucose were sampled throughout. The DSC consisted of a mental arithmetic challenge and a modified Stroop Color Word, which alternated every 2 min for 20 min. Upon completion of the DSC, responses for correct, incorrect, and no responses were recorded for the mental arithmetic challenge and Stroop Color Word. Blood ß-OHB was elevated with KS by -15 min and remained so throughout (p < .001), peaking at 0.76 ± 0.32 mM. Blood glucose was lower with KS compared with the placebo at -15 and 10 min by 9% and 5%, respectively (both ps < .05). There were no differences between the treatments for heart rate, rating of perceived exertion, mental arithmetic challenge, or Stroop Color Word. Overall, this study suggests that KSs are not effective aids for enhancing cognitive performance during a DSC, which might partially be explained by the inability of currently available commercial KS supplements to elevate ß-OHB blood concentrations above ∼1.0 mM.