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The aim was to use a robust statistical approach to examine whether physical fitness at entry influences performance changes between men and women undertaking British Army basic training (BT). Performance of 2 km run, seated medicine ball throw (MBT) and isometric mid-thigh pull (MTP) were assessed at entry and completion of Standard Entry (SE), Junior Entry-Short (JE-Short), and Junior Entry-Long (JE-Long) training for 2350 (272 women) recruits. Performance change was analyzed with entry performance as a covariate (ANCOVA), with an additional interaction term allowing different slopes for courses and genders (p < 0.05). Overall, BT courses saw average improvements in 2 km run performance (SE: -6.8% [-0.62 min], JE-Short: -4.6% [-0.43 min], JE-Long: -7.7% [-0.70 min]; all p < 0.001) and MBT (1.0-8.8% [0.04-0.34 m]; all p < 0.05) and MTP (4.5-26.9% [6.5-28.8 kg]; all p < 0.001). Regression models indicate an expected form of "regression to the mean" whereby test performance change was negatively associated with entry fitness in each course (those with low baseline fitness exhibit larger training improvements; all interaction effects: p < 0.001, η p 2 $$ {\eta}_{\mathrm{p}}^2 $$ > 0.006), particularly for women. However, when matched for entry fitness, men displayed considerable improvements in all tests, relative to women. Training courses were effective in developing recruit physical fitness, whereby the level of improvement is, in large part, dependent on entry fitness. Factors including age, physical maturity, course length, and physical training, could also contribute to the variability in training response between genders and should be considered when analyzing and/or developing physical fitness in these cohorts for future success of military job-task performance.
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Militares , Feminino , Humanos , Masculino , Exercício Físico , Teste de Esforço , Aptidão Física/fisiologia , Desempenho Físico Funcional , Análise e Desempenho de TarefasRESUMO
Military training is physically arduous and associated with high injury incidence. Unlike in high-performance sport, the interaction between training load and injury has not been extensively researched in military personnel. Sixty-three (43 men, 20 women; age 24 ± 2 years; stature 1.76 ± 0.09 m; body mass 79.1 ± 10.8 kg) British Army Officer Cadets undergoing 44 weeks of training at the Royal Military Academy Sandhurst volunteered to participate. Weekly training load (cumulative 7-day moderate-vigorous physical activity [MVPA], vigorous PA [VPA], and the ratio between MVPA and sedentary-light PA [SLPA; MVPA:SLPA]) was monitored using a wrist-worn accelerometer (GENEActiv, UK). Self-report injury data were collected and combined with musculoskeletal injuries recorded at the Academy medical center. Training loads were divided into quartiles with the lowest load group used as the reference to enable comparisons using odds ratios (OR) and 95% confidence intervals (95% CI). Overall injury incidence was 60% with the most common injury sites being the ankle (22%) and knee (18%). High (load; OR; 95% CI [>2327 mins; 3.44; 1.80-6.56]) weekly cumulative MVPA exposure significantly increased odds of injury. Similarly, likelihood of injury significantly increased when exposed to low-moderate (0.42-0.47; 2.45 [1.19-5.04]), high-moderate (0.48-0.51; 2.48 [1.21-5.10]), and high MVPA:SLPA loads (>0.51; 3.60 [1.80-7.21]). High MVPA and high-moderate MVPA:SLPA increased odds of injury by ~2.0 to 3.5 fold, suggesting that the ratio of workload to recovery is important for mitigating injury occurrence.
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Exercício Físico , Militares , Masculino , Humanos , Feminino , Adulto Jovem , Adulto , Incidência , AcelerometriaRESUMO
BACKGROUND: Dismounted military operations require soldiers to complete cognitive tasks whilst undertaking demanding and repeated physical taskings. OBJECTIVE: To assess the effects of repeated fast load carriage bouts on cognitive performance, perceptual responses, and psychophysiological markers. METHODS: Twelve civilian males (age, 28 ± 8 y; stature, 186 ± 6 cm; body mass 84.3 ± 11.1 kg; VÌO2max, 51.5 ± 6.4 mL·kg-1·min-1) completed three â¼65-min bouts of a Fast Load Carriage Protocol (FLCP), each interspersed with a 65-min recovery period, carrying a representative combat load of 25 kg. During each FLCP, cognitive function was assessed using a Shoot/Don't-Shoot Task (SDST) and a Military-Specific Auditory N-Back Task (MSANT), along with subjective ratings. Additional psychophysiological markers (heart rate variability, salivary cortisol, and dehydroepiandrosterone-sulfate concentrations) were also measured. RESULTS: A main effect of bout on MSANT combined score metric (p < .001, Kendall's W = 69.084) and for time on the accuracy-speed trade-off parameter of the SDST (p = .025, Ñ 2 = .024) was evident. These likely changes in cognitive performance were coupled with subjective data indicating that participants perceived that they increased their mental effort to maintain cognitive performance (bout: p < .001, Ñ 2 = .045; time: p < .001, Ñ 2 = .232). Changes in HRV and salivary markers were also evident, likely tracking increased stress. CONCLUSION: Despite the increase in physiological and psychological stress, cognitive performance was largely maintained; purportedly a result of increased mental effort. APPLICATION: Given the likely increase in dual-task interference in the field environment compared with the laboratory, military commanders should seek approaches to manage cognitive load where possible, to maintain soldier performance.
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PURPOSE: Investigate the impact of sex, menstrual cycle phase and oral contraceptive use on intestinal permeability and ex-vivo tumour necrosis factor alpha (TNFα) release following treatment with lipopolysaccharide (LPS) and hyperthermia. METHODS: Twenty-seven participants (9 men, 9 eumenorrheic women (MC) and 9 women taking an oral contraceptive pill (OC)) completed three trials. Men were tested on 3 occasions over 6 weeks; MC during early-follicular, ovulation, and mid-luteal phases; OC during the pill and pill-free phase. Intestinal permeability was assessed following a 4-hour dual sugar absorption test (lactulose: rhamnose). Venous blood was collected each trial and stimulated with 100 µg·mL-1 LPS before incubation at 37 °C and 40 °C and analysed for TNFα via ELISA. RESULTS: L:R ratio was higher in OC than MC (+0.003, p = 0.061) and men (+0.005, p = 0.007). Men had higher TNFα responses than both MC (+53 %, p = 0.004) and OC (+61 %, p = 0.003). TNFα release was greater at 40 °C than 37 °C (+23 %, p < 0.001). CONCLUSIONS: Men present with lower resting intestinal barrier permeability relative to women regardless of OC use and displayed greater monocyte TNFα release following whole blood treatment with LPS and hyperthermia. Oral contraceptive users had highest intestinal permeability however, neither permeability or TNFα release were impacted by the pill cycle. Although no statistical effect was seen in the menstrual cycle, intestinal permeability and TNFα release were more variable across the phases.
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Hipertermia Induzida , Lipopolissacarídeos , Anticoncepcionais Orais/farmacologia , Feminino , Humanos , Lipopolissacarídeos/farmacologia , Masculino , Ciclo Menstrual , Monócitos , Permeabilidade , Fator de Necrose Tumoral alfaRESUMO
Dietary intake and physical activity impact performance and adaptation during training. The aims of this study were to compare energy and macronutrient intake during British Army Officer Cadet training with dietary guidelines and describe daily distribution of energy and macronutrient intake and estimated energy expenditure. Thirteen participants (seven women) were monitored during three discrete periods of military training for 9 days on-camp, 5 days of field exercise, and 9 days of a mixture of the two. Dietary intake was measured using researcher-led food weighing and food diaries, and energy expenditure was estimated from wrist-worn accelerometers. Energy intake was below guidelines for men (4,600 kcal/day) and women (3,500 kcal/day) during on-camp training (men = -16% and women = -9%), field exercise (men = -33% and women = -42%), and combined camp and field training (men and women both -34%). Carbohydrate intake of men and women were below guidelines (6 g·kg-1·day-1) during field exercise (men = -18% and women = -37%) and combined camp and field training (men = -33% and women = -39%), respectively. Protein intake was above guidelines (1.2 kcal·kg-1·day-1) for men and women during on-camp training (men = 48% and women = 39%) and was below guidelines during field exercise for women only (-27%). Energy and macronutrient intake during on-camp training centered around mealtimes with a discernible sleep/wake cycle for energy expenditure. During field exercise, energy and macronutrient intake were individually variable, and energy expenditure was high throughout the day and night. These findings could be used to inform evidenced-based interventions to change the amount and timing of energy and macronutrient intake around physical activity to optimize performance and adaptations during military training.
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Militares , Condicionamento Físico Humano , Ingestão de Alimentos , Ingestão de Energia , Metabolismo Energético , Exercício Físico , Feminino , Humanos , MasculinoRESUMO
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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Militares , Adulto , Ingestão de Energia , Metabolismo Energético , Exercício Físico , Feminino , Humanos , Estado Nutricional , Adulto JovemRESUMO
ABSTRACT: Vine, CA, Coakley, SL, Blacker, SD, Doherty, J, Hale, B, Walker, EF, Rue, CA, Lee, BJ, Flood, TR, Knapik, JJ, Jackson, S, Greeves, JP, and Myers, SD. Accuracy of metabolic cost predictive equations during military load carriage. J Strength Cond Res 36(5): 1297-1303, 2022-To quantify the accuracy of 5 equations to predict the metabolic cost of load carriage under ecologically valid military speed and load combinations. Thirty-nine male serving infantry soldiers completed thirteen 20-minute bouts of overground load carriage comprising 2 speeds (2.5 and 4.8 km·h-1) and 6 carried equipment load combinations (25, 30, 40, 50, 60, and 70 kg), with 22 also completing a bout at 5.5 km·h-1 carrying 40 kg. For each speed-load combination, the metabolic cost was measured using the Douglas bag technique and compared with the metabolic cost predicted from 5 equations; Givoni and Goldman, 1971 (GG), Pandolf et al. 1997 (PAN), Santee et al. 2001 (SAN), American College of Sports Medicine 2013 (ACSM), and the Minimum-Mechanics Model (MMM) by Ludlow and Weyand, 2017. Comparisons between measured and predicted metabolic cost were made using repeated-measures analysis of variance and limits of agreement. All predictive equations, except for PAN, underpredicted the metabolic cost for all speed-load combinations (p < 0.001). The PAN equation accurately predicted metabolic cost for 40 and 50 kg at 4.8 km·h-1 (p > 0.05), underpredicted metabolic cost for all 2.5 km·h-1 speed-load combinations as well as 25 and 30 kg at 4.8 km·h-1, and overpredicted metabolic cost for 60 and 70 kg at 4.8 km·h-1 (p < 0.001). Most equations (GG, SAN, ACSM, and MMM) underpredicted metabolic cost while one (PAN) accurately predicted at moderate loads and speeds, but overpredicted or underpredicted at other speed-load combinations. Our findings indicate that caution should be applied when using these predictive equations to model military load carriage tasks.
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Militares , Esportes , Metabolismo Energético , Humanos , Masculino , Caminhada , Suporte de CargaRESUMO
Supplementation with anthocyanin-rich blackcurrant increases blood flow, cardiac output, and stroke volume at rest. It is not known whether cardiovascular responses can be replicated over longer timeframes in fed trained cyclists. In a randomized, double-blind, crossover design, 13 male trained cyclists (age 39 ± 10 years, VËO2max 55.3 ± 6.7 ml·kg-1·min-1) consumed two doses of New Zealand blackcurrant (NZBC) extract (300 and 600 mg/day for 1 week). Cardiovascular parameters were measured during rest and submaximal cycling (65% VËO2max) on day 1 (D1), D4, and D7. Data were analyzed with an RM ANOVA using dose (placebo vs. 300 vs. 600 mg/day) by time point (D1, D4, and D7). Outcomes from placebo were averaged to determine the coefficient of variation within our experimental model, and 95% confidence interval (CI) was examined for differences between placebo and NZBC. There were no differences in cardiovascular responses at rest between conditions and between days. During submaximal exercise, no positive changes were observed on D1 and D4 after consuming NZBC extract. On D7, intake of 600 mg increased stroke volume (3.08 ml, 95% CI [-2.08, 8.26]; d = 0.16, p = .21), cardiac output (0.39 L/min, 95% CI [-1.39, .60]; d = 0.14, p = .40) (both +2.5%), and lowered total peripheral resistance by 6.5% (-0.46 mmHg·min/ml, 95% CI [-1.80, .89]; d = 0.18, p = .46). However, these changes were trivial and fell within the coefficient of variation of our study design. Therefore, we can conclude that NZBC extract was not effective in enhancing cardiovascular function during rest and submaximal exercise in endurance-trained fed cyclists.
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Ciclismo/fisiologia , Suplementos Nutricionais , Hemodinâmica/efeitos dos fármacos , Extratos Vegetais/administração & dosagem , Ribes , Adulto , Pressão Sanguínea/efeitos dos fármacos , Débito Cardíaco/efeitos dos fármacos , Estudos Cross-Over , Método Duplo-Cego , Frequência Cardíaca/efeitos dos fármacos , Humanos , Masculino , Pessoa de Meia-Idade , Nova Zelândia , Consumo de Oxigênio/efeitos dos fármacos , Descanso , Volume Sistólico/efeitos dos fármacos , Resistência Vascular/efeitos dos fármacosRESUMO
New Zealand blackcurrant (NZBC) contains anthocyanins, known to moderate blood flow and display anti-inflammatory properties that may improve recovery from exercise-induced muscle damage. The authors examined whether NZBC extract supplementation enhances recovery from exercise-induced muscle damage after a half-marathon race. Following a randomized, double-blind, independent groups design, 20 (eight women) recreational runners (age 30 ± 6 years, height 1.73 ± 0.74 m, body mass 68.5 ± 7.8 kg, half-marathon finishing time 1:56:33 ± 0:18:08 hr:min:s) ingested either two 300-mg/day capsules of NZBC extract (CurraNZ™) or a visually matched placebo, for 7 days prior to and 2 days following a half-marathon. Countermovement jump performance variables, urine interleukin-6, and perceived muscle soreness and fatigue were measured pre, post, and at 24 and 48 hr after the half-marathon and analyzed using a mixed linear model with statistical significance set a priori at p < .05. The countermovement jump performance variables were reduced immediately post-half-marathon (p < .05), with all returning to pre-half-marathon levels by 48 hr, except the concentric and eccentric peak force and eccentric duration, with no difference in response between groups (p > .05). Urine interleukin-6 increased 48-hr post-half-marathon in the NZBC group only (p < .01) and remained unchanged compared with pre-half-marathon levels in the placebo group (p > .05). Perceived muscle soreness and fatigue increased immediately post-half-marathon (p < .01) and returned to pre-half-marathon levels by 48 hr, with no difference between groups (p > .05). Supplementation with NZBC extract had no effect on the recovery of countermovement jump variables and perceptions of muscle soreness or fatigue following a half-marathon in recreational runners.
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Corrida de Maratona , Fadiga Muscular/efeitos dos fármacos , Músculo Esquelético/fisiologia , Mialgia/tratamento farmacológico , Extratos Vegetais/administração & dosagem , Ribes/química , Adulto , Suplementos Nutricionais , Método Duplo-Cego , Feminino , Humanos , Masculino , Nova Zelândia , Fenômenos Fisiológicos da Nutrição Esportiva , Adulto JovemRESUMO
Wearable physical activity (PA) monitors have improved the ability to estimate free-living total energy expenditure (TEE) but their application during arduous military training alongside more well-established research methods has not been widely documented. This study aimed to assess the validity of two wrist-worn activity monitors and a PA log against doubly labeled water (DLW) during British Army Officer Cadet (OC) training. For 10 days of training, twenty (10 male and 10 female) OCs (mean ± SD: age 23 ± 2 years, height 1.74 ± 0.09 m, body mass 77.0 ± 9.3 kg) wore one research-grade accelerometer (GENEActiv, Cambridge, UK) on the dominant wrist, wore one commercially available monitor (Fitbit SURGE, USA) on the non-dominant wrist, and completed a self-report PA log. Immediately prior to this 10-day period, participants consumed a bolus of DLW and provided daily urine samples, which were analyzed by mass spectrometry to determine TEE. Bivariate correlations and limits of agreement (LoA) were employed to compare TEE from each estimation method to DLW. Average daily TEE from DLW was 4112 ± 652 kcal·day-1 against which the GENEActiv showed near identical average TEE (mean bias ± LoA: -15 ± 851 kcal. day-1 ) while Fitbit tended to underestimate (-656 ± 683 kcal·day-1 ) and the PA log substantially overestimate (+1946 ± 1637 kcal·day-1 ). Wearable physical activity monitors provide a cheaper and more practical method for estimating free-living TEE than DLW in military settings. The GENEActiv accelerometer demonstrated good validity for assessing daily TEE and would appear suitable for use in large-scale, longitudinal military studies.
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Acelerometria/instrumentação , Metabolismo Energético , Monitores de Aptidão Física , Condicionamento Físico Humano , Adulto , Óxido de Deutério , Feminino , Humanos , Masculino , Militares , Adulto JovemRESUMO
Nootropics are compounds that enhance cognitive performance and have been highlighted as a medium-term human augmentation technology that could support soldier performance. Given the differing ethical, safety and legal considerations associated with the pharmaceutical subset of nootropics, this analysis focuses on dietary supplementation which may enhance cognition during training and operations. Numerous supplements have been investigated as possible nootropics; however, research is often not context specific or of high quality, leading to questions regarding efficacy. There are many other complex cofactors that may affect the efficacy of any dietary nootropic supplement which is designed to improve cognition, such as external stressors (eg, sleep deprivation, high physical workloads), task specifics (eg, cognitive processes required) and other psychological constructs (eg, placebo/nocebo effect). Moreover, military population considerations, such as prior nutritional knowledge and current supplement consumption (eg, caffeine), along with other issues such as supplement contamination, should be evaluated when considering dietary nootropic use within military populations. However, given the increasing requirement for cognitive capabilities by military personnel to complete role-related tasks, dietary nootropics could be highly beneficial in specific contexts. While current evidence is broadly weak, nutritional nootropic supplements may be of most use to the military end user during periods of high military specific stress. Currently, caffeine and L-tyrosine are the leading nootropic supplement candidates within the military context. Future military-specific research on nootropics should be of high quality and use externally valid methodologies to maximise the translation of research to practice.
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Bouts of military load carriage are rarely completed in isolation; however, limited research has investigated the physiological responses to repeated load carriage tasks. Twelve civilian men (age, 28 ± 8 years; stature, 185.6 ± 5.8 cm; body mass 84.3 ± 11.1 kg and maximal oxygen uptake, 51.5 ± 6.4 mL·kg-1 min-1) attended the laboratory on two occasions to undertake a familiarisation and an experimental session. Following their familiarisation session, participants completed three bouts of a fast load carriage protocol (FLCP; â¼65 min), carrying 25 kg, interspersed with a 65-min recovery period. Physiological strain (oxygen uptake [VÌO2] and heart rate [HR]) was assessed during the FLCP bouts, and physical performance assessments (weighted counter-movement jump [wCMJ], maximal isometric voluntary contraction of the quadriceps [MIVC] and seated medicine ball throw [SMBT]) was measured pre and post each FLCP bout. A main effect for bout and measurement time was evident for VÌO2 and HR (both p < 0.001 and Ñ 2 = 0.103-0.816). There was no likely change in SMBT distance (p = 0.201 and Ñ 2 = 0.004), but MIVC peak force reduced by approximately 25% across measurement points (p < 0.001 and Ñ 2 = 0.133). A mean percentage change of approximately -12% from initial values was also evident for peak wCMJ height (p = 0.001 and Ñ 2 = 0.028). Collectively, these data demonstrate that repeated FLCP bouts result in an elevated physiological strain for each successive bout, along with a substantial reduction in lower body power (wCMJ and MIVC). Therefore, future research should investigate possible mitigation strategies to maintain role-related capability.
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Teste de Esforço , Frequência Cardíaca , Militares , Consumo de Oxigênio , Suporte de Carga , Humanos , Masculino , Frequência Cardíaca/fisiologia , Consumo de Oxigênio/fisiologia , Adulto , Adulto Jovem , Suporte de Carga/fisiologia , Contração Isométrica/fisiologia , Músculo Quadríceps/fisiologia , Percepção/fisiologiaRESUMO
BACKGROUND: There is a requirement for British Army personnel to operate in/around water. Assessing role-related swimming/water competence will support personnel to conduct their job-roles safely and effectively. OBJECTIVE: To undertake a Job-Task Analysis (JTA) of British Army personnel when working in/around water and use this information to develop a Swimming Representative Military Task (RMT) to assess swimming/water competence. METHODS: Workshops, surveys, and observations were used to conduct a JTA, which identified and described job-tasks conducted by British Army personnel in/around water. Ergonomic analysis of these job-tasks identified seven water-based physical actions, which were considered fundamental for all personnel to be competent in performing. These seven actions guided design of a Swimming RMT, which was subsequently conducted twice by 103 serving personnel (89 men, 11 women) and once by 65 recruits (49 men, 16 women). RESULTS: The RMT comprised of entering the water in combat fatigues and webbing, removing webbing, swimming 50âm, and staying afloat for up to 10 minutes. During RMT trials, in trial 1, 85% of serving personnel and 74% of recruits successfully completed the RMT, which increased to 93% in serving personnel for trial 2. Across trials 1 and 2, all three timed RMT elements showed moderate-high correlational reliability (ICC range: 0.462-0.791). On average, serving personnel were quicker to complete the 50âm swim phase compared to recruits (91±24âs vs. 100±26âs; Uâ=â2575.0, rbâ=â-0.192, pâ=â0.039). CONCLUSIONS: The JTA-informed Swimming RMT provides an assessment of the minimum role-related swimming/water competence standard for British Army personnel.
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The aim of this study was to quantify the physiological responses of Police Officers wearing chemical, biological, radiological and nuclear personal protective equipment (CBRN PPE) during firearms house entry (FE) unarmed house entry (UE) and crowd control (CC) simulations. Participants volunteered from the UK Police Force [FE (n = 6, age 33 ± 4 years, body mass 85.3 ± 7.9 kg, (·)VO2max 53 ± 5 ml · kg⻹ · min⻹), UE and CC (n = 11, age 34 ± 5 years, body mass 88.5 ± 13.8 kg, (·)VO2max 51 ± 5 ml · kg⻹ · min⻹)]. Heart rate reserve (HRR) during FE was greater than UE (74 ± 7 vs. 62 ± 6%HRR, p = 0.01) but lower in CC (39 ± 7%HRR, p < 0.01). Peak core body temperature was greater during FE (39.2 ± 0.3°C) than UE (38.9 ± 0.4°C, p < 0.01) and CC (37.5 ± 0.3°C, p < 0.01), with similar trends in skin temperature. There were no differences in the volume of water consumed (1.13 ± 0.44 l, p = 0.51) or change in body mass (-1.68 ± 0.65 kg, p = 0.74) between simulations. The increase in body temperature was a primary physiological limitation to performance. Cooling strategies and revised operating procedures may improve Police Officers' physical performance while wearing CBRN PPE. PRACTITIONER SUMMARY: In recent years, the likelihood of Police Officers having to respond to a chemical, biological, nuclear or radiological (CBRN) incident wearing personal protective equipment (PPE) has increased. Such apparel is likely to increase physiological strain and impair job performance; understanding these limitations may help improve Officer safety and operational effectiveness.
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Temperatura Corporal/fisiologia , Aplicação da Lei , Exposição Ocupacional/prevenção & controle , Esforço Físico/fisiologia , Roupa de Proteção , Dispositivos de Proteção Respiratória , Adulto , Derramamento de Material Biológico , Peso Corporal , Vazamento de Resíduos Químicos , Feminino , Frequência Cardíaca/fisiologia , Humanos , Masculino , Liberação Nociva de Radioativos , Temperatura Cutânea/fisiologiaRESUMO
The intake of anthocyanin-rich New Zealand blackcurrant (NZBC) extract (300 mg per day) over a week enhanced 16.1 km cycling time trial (TT) performance in endurance-trained cyclists without acute performance effects. In the present study, the acute effects of an intake of 900 mg of NZBC extract 2 h before performing the 16.1 km cycling TT were examined. A total of 34 cyclists (26 males; 8 females) (age: 38 ± 7 years, VËO2max: 57 ± 5 mL·kg-1·min-1) completed 4 16.1 km TTs (2 familiarization and 2 experimental trials) over 4 mornings on a home turbo-trainer connected with the online training simulator ZWIFT. There was no difference in time to complete the 16.1 km TT between conditions (placebo: 1422 ± 104 s; NZBC extract: 1414 ± 93 s, p = 0.07). However, when participants were split between faster (<1400 s; 1 female; 16 males) and slower (>1400 s; 7 females; 10 males) cyclists based on average familiarization TTs, a difference in TT performance was observed only in the slower group (placebo: 1499 ± 91 s; NZBC extract: 1479 ± 83 s, p = 0.02). At 12 km (quartile analysis), power output (p = 0.04) and speed (p = 0.04) were higher compared to the placebo with no effects on heart rate and cadence. The acute effects of 900 mg of NZBC extract on a 16.1 km cycling time-trial may depend on the performance ability of male endurance-trained cyclists. More work is needed to address whether there is a sex-specific time-trial effect of NZBC extract independent of performance ability.
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This study investigated sex differences in, and the effect of protein supplementation on, bone metabolism during a 36-h military field exercise. Forty-four British Army Officer cadets (14 women) completed a 36-h field exercise. Participants consumed either their habitual diet [n = 14 women (Women) and n = 15 men (Men Controls)] or the habitual diet with an additional 46.6 g·day-1 of protein for men [n = 15 men (Men Protein)]. Women and Men Protein were compared with Men Controls to examine the effect of sex and protein supplementation. Circulating markers of bone metabolism were measured before, 24 h after (postexercise), and 96 h after (recovery) the field exercise. Beta C-telopeptide cross links of type 1 collagen and cortisol were not different between time points or Women and Men Controls (P ≥ 0.094). Procollagen type I N-terminal propeptide decreased from baseline to postexercise (P < 0.001) and recovery (P < 0.001) in Women and Men Controls. Parathyroid hormone (PTH) increased from baseline to post-exercise (P = 0.006) and decreased from postexercise to recovery (P = 0.047) in Women and Men Controls. Total 25(OH)D increased from baseline to postexercise (P = 0.038) and recovery (P < 0.001) in Women and Men Controls. Testosterone decreased from baseline to post-exercise (P < 0.001) and recovery (P = 0.007) in Men Controls, but did not change for Women (all P = 1.000). Protein supplementation in men had no effect on any marker. Men and women experience similar changes to bone metabolism-decreased bone formation and increased PTH-following a short-field exercise. Protein had no protective effect likely because of the energy deficit.NEW & NOTEWORTHY Energy deficits are common in arduous military training and can cause disturbances to bone metabolism. This study provides first evidence that short periods of severe energy deficit and arduous exercise-in the form of a 36-h military field exercise-can suppress bone formation for at least 96 h, and the suppression in bone formation was not different between men and women. Protein feeding does not offset decreases in bone formation during severe energy deficits.
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Militares , Humanos , Masculino , Feminino , Hormônio Paratireóideo , Osso e Ossos , Suplementos Nutricionais , Metabolismo EnergéticoRESUMO
BACKGROUND: Despite the importance of hydration, limited research on the topic has been undertaken in Arabic populations. METHODS: Study 1. Five sequential daily midmorning urine samples were provided by 88 adult military cadets and 32 school-based adolescents. Hydration thresholds were produced using percentiles of estimated urine osmolality (Uosm) and urine color (Ucol). Study 2. The authors assessed 1,077 midmorning urine samples from 120 military cadets and 52 adolescents for the Uosm:Ucol relationship using regression. Study 3. The authors conducted a 4-wk hydration campaign in which 21 adolescents participated, providing urine samples before (PreC), at the end of (EndC), and 2 wk after the campaign (PostC). RESULTS: Study 1. Euhydration (41-60th percentile) was 881-970 mOsmol/kg in adults and 821-900 mOsmol/kg in adolescents. Study 2. In both cohorts, Uosm and Ucol were associated (p < .01): adults R² = .33, adolescents R² = .59. Study 3. Urine osmolality was significantly higher PreC than at EndC and PostC. CONCLUSIONS: Urinary output of Arabic adolescents and military cadets was more concentrated than frequently recommended for euhydration. Further work in similar populations is required to determine if these values represent hypohydration or merely reflect dietary and cultural differences. In male Arabic adolescents and adults, Ucol was an adequate indicator of hydration status. Favorable hydration changes were made after a school-based health campaign.
Assuntos
Desidratação/urina , Comportamento de Ingestão de Líquido , Promoção da Saúde , Adolescente , Índice de Massa Corporal , Humanos , Masculino , Concentração Osmolar , Instituições Acadêmicas , Emirados Árabes Unidos , Equilíbrio Hidroeletrolítico , Adulto JovemRESUMO
Dark-colored fruits, especially berries, have abundant presence of the polyphenol anthocyanin which have been show to provide health benefits. Studies with the berry blackcurrant have provided notable observations with application for athletes and physically active individuals. Alterations in exercise-induced substrate oxidation, exercise performance of repeated high-intensity running and cycling time-trial and cardiovascular function at rest and during exercise were observed with intake of New Zealand blackcurrant. The dynamic plasma bioavailability of the blackcurrant anthocyanins and the anthocyanin-derived metabolites must have changed cell function to provide meaningful in-vivo physiological effects. This perspective will reflect on the research studies for obtaining the applied in-vivo effects by intake of anthocyanin-rich supplementation, the issue of individual responses, and the emerging strong potential of anthocyanins for sport and exercise nutrition. Future work with repeated intake of known amount and type of anthocyanins, gut microbiota handling of anthocyanins, and coinciding measurements of plasma anthocyanin and anthocyanin-derived metabolites and in-vivo cell function will be required to inform our understanding for the unique potential of anthocyanins as a nutritional ergogenic aid for delivering meaningful effects for a wide range of athletes and physically active individuals.
RESUMO
New Zealand blackcurrant (NZBC) extract is a rich source of anthocyanins and in order to exert physiological effects, the anthocyanin-derived metabolites need to be bioavailable in vivo. We examined the plasma uptake of selected phenolic acids following NZBC extract supplementation alongside maintaining a habitual diet (i.e. not restricting habitual polyphenol intake). Twenty healthy volunteers (nine females, age: 28 ± 7 years, height 1.73 ± 0.09 m, body mass 73 ± 11 kg) consumed a 300 mg NZBC extract capsule (CurraNZ®; anthocyanin content 105 mg) following an overnight fast. Venous blood samples were taken pre and 1, 1.5, 2, 3, 4, 5, and 6 h post-ingestion of the capsule. Reversed-phase high-performance liquid chromatography (HPLC) was used for analysis of two dihydroxybenzoic acids [i.e. vanillic acid (VA) and protocatechuic acid (PCA)] and one trihydroxybenzoic acid [i.e. gallic acid (GA)] in plasma following NZBC extract supplementation. Habitual anthocyanin intake was 168 (95%CI:68-404) mgâ day-1 and no associations were observed between this and VA, PCA, and GA plasma uptake by the NZBC extract intake. Plasma time-concentration curves revealed that GA, and PCA were most abundant at 4, and 1.5 h post-ingestion, representing a 261% and 320% increase above baseline, respectively, with VA remaining unchanged. This is the first study to demonstrate that an NZBC extract supplement increases the plasma uptake of phenolic acids GA, and PCA even when a habitual diet is followed in the days preceding the experimental trial, although inter-individual variability is apparent.
Assuntos
Antocianinas , Ribes , Adulto , Suplementos Nutricionais , Feminino , Ácido Gálico , Humanos , Masculino , Nova Zelândia , Extratos Vegetais , Ribes/química , Adulto JovemRESUMO
Military personnel are required to complete physically demanding tasks when performing work and training, which may be quantified through the physical stress imposed (external load) or the resultant physiological strain (internal load). The aim of this narrative review is to provide an overview of the techniques used to monitor work and training load in military settings, summarise key findings, and discuss important practical, analytical, and conceptual considerations. Most investigations have focused upon measuring external and internal load in military training environments; however, limited data exist in operational settings. Accelerometry has been the primary tool used to estimate external load, with heart rate commonly used to quantify internal load. Supplemental to heart rate, psychophysiological and biochemical measures have also been investigated to elucidate aspects of internal load. Broadly, investigations have revealed that military training requires personnel to perform relatively large volumes of physical activity (e.g. averaging â¼15,000 steps·day-1) of typically low-moderate intensity activity (<6 MET), although considerable temporal and inter-individual variability is observed from these gross mean estimates. There are limitations associated with these measures and, at best, estimates of external and internal load can only be inferred. These limitations are particularly pertinent for military tasks such as load carriage and manual material handling, which often involve complex activities performed individually or in teams, in a range of operational environments, with multiple layers of protection, over a protracted duration. Comprehensively quantifying external and internal loads during these functional activities poses substantial practical and analytical challenges.