Omega-3 Status Evaluation in Australian Female Rugby League Athletes: Ad Libitum Fish Oil Provision Results in a Varied Omega-3 Index.

Optimal omega-3 status, influenced by increased intake of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), is vital for physiological health. This study investigated the impact of ad libitum fish oil supplementation on the omega-3 status of female athletes in a professional rugby league team during a competitive season. Twenty-four (n = 24) athletes participated, and their omega-3 status was assessed using the Omega-3 Index (O3I) and arachidonic acid (AA) to EPA ratio through finger-prick blood samples taken at the start and end of the season. They were given access to a fish oil supplement (PILLAR Performance, Australia) with a recommended daily dose of four capsules per day (2,160 mg EPA and 1,440 mg docosahexaenoic acid). At the beginning of the season, the group mean O3I was 4.77% (95% confidence interval [CI: 4.50, 5.04]) and the AA to EPA ratio was 14.89 (95% CI [13.22, 16.55]). None of the athletes had an O3I exceeding 8%. By the season's end, the O3I was a significantly increased to 7.28% (95% CI [6.64, 7.93], p < .0001) and AA to EPA ratio significantly decreased to a mean of 6.67 (95% CI [5.02, 8.31], p < .0001), driven primarily by the significant increase in EPA of +1.14% (95% CI [0.77, 1.51], p < .0001). However, these changes were varied between the athletes and most likely due to compliance. This study has demonstrated that using the objective O3I feedback scale is possible with elite female rugby athletes, but individual strategies will be required to achieve daily intake targets of EPA + DHA.

A review and evaluation of study design considerations for omega-3 fatty acid supplementation trials in physically trained participants.

Long-chain omega-3 polyunsaturated fatty acid (LC n-3 PUFA) supplements, rich in eicosapentaenoic acid and/or docosahexaenoic acid, are increasingly being recommended within athletic institutions. However, the wide range of doses, durations and study designs implemented across trials makes it difficult to provide clear recommendations. The importance of study design characteristics in LC n-3 PUFA trials has been detailed in cardiovascular disease research, and these considerations may guide LC n-3 PUFA study design in healthy cohorts. This systematic review examined the quality of studies and study design considerations used in evaluating the evidence for LC n-3 PUFA improving performance in physically trained adults. SCOPUS, PubMed and Web of Science electronic databases were searched to identify studies that supplemented LC n-3 PUFA in physically trained participants. Forty-six (n = 46) studies met inclusion. Most studies used a randomised control design. Risk of bias, assessed using the design-appropriate Cochrane Collaboration tool, revealed that studies had a predominant judgment of 'some concerns', 'high risk' or 'moderate risk' in randomised controlled, randomised crossover or non-randomised studies, respectively. A custom five-point quality assessment scale demonstrated that no study satisfied all recommendations for LC n-3 PUFA study design. This review has highlighted that the disparate range of study designs is likely contributing to the inconclusive state of outcomes pertaining to LC n-3 PUFA as a potential ergogenic aid. Further research must adequately account for the specific LC n-3 PUFA study design considerations, underpinned by a clear hypothesis, to achieve evidence-based dose, duration and composition recommendations for physically trained individuals.

Overnight sleeping heart rate variability of Army recruits during a 12-week basic military training course.

PURPOSE: This study aimed to quantify sleeping heart rate (HR) and HR variability (HRV) alongside circulating tumor necrosis factor alpha (TNFα) concentrations during 12-week Basic Military Training (BMT). We hypothesised that, despite a high allostatic load, BMT would increase cardiorespiratory fitness and HRV, while lowering both sleeping HR and TNFα in young healthy recruits. METHODS: Sixty-three recruits (18-43 years) undertook ≥ 2 overnight cardiac frequency recordings in weeks 1, 8 and 12 of BMT with 4 h of beat-to-beat HR collected between 00:00 and 06:00 h on each night. Beat-to-beat data were used to derive HR and HRV metrics which were analysed as weekly averages (totalling 8 h). A fasted morning blood sample was collected in the equivalent weeks for the measurement of circulating TNFα concentrations and predicted VO2max was assessed in weeks 2 and 8. RESULTS: Predicted VO2max was significantly increased at week 8 (+ 3.3 ± 2.6 mL kg-1 min-1; p < 0.001). Sleeping HR (wk1, 63 ± 7 b min-1) was progressively reduced throughout BMT (wk8, 58 ± 6; wk12, 55 ± 6 b min-1; p < 0.01). Sleeping HRV reflected by the root mean square of successive differences (RMSSD; wk1, 86 ± 50 ms) was progressively increased (wk8, 98 ± 50; wk12, 106 ± 52 ms; p < 0.01). Fasted circulating TNFα (wk1, 9.1 ± 2.8 pg/mL) remained unchanged at wk8 (8.9 ± 2.5 pg/mL; p = 0.79) but were significantly reduced at wk12 (8.0 ± 2.4 pg/mL; p < 0.01). CONCLUSION: Increased predicted VO2max, HRV and reduced HR during overnight sleep are reflective of typical cardiorespiratory endurance training responses. These results indicate that recruits are achieving cardiovascular health benefits despite the high allostatic load associated with the 12-week BMT.

The impact of age, type 2 diabetes and hypertension on heart rate variability during rest and exercise at increasing levels of heat stress.

PURPOSE: In older adults with type 2 diabetes (T2D) and hypertension (HTN), cardiac autonomic modulation is markedly attenuated during exercise-heat stress. However, the extent to which this impairment is evident under increasing levels of heat stress remains unknown. METHODS: We examined heart rate variability (HRV), a surrogate of cardiac autonomic modulation, during incremental exercise-heat stress exposures in young (20-30 years) and middle-aged-to-older individuals (50-70 years) without and with T2D and HTN. Thirteen young and healthy (Young, n = 13) and 37 older men without (Older, n = 14) and with HTN (n = 13) or T2D (n = 10) performed 180-min treadmill walking at a fixed metabolic rate (~ 200 W/m2; ~ 3.5 METs) in a differing wet-bulb globe temperature (WBGT; 16 °C, 24 °C, 28 °C, and 32 °C). Electrocardiogram (ECG) and core temperature measurements were recorded throughout. Data were analysed using 5-min averaged epochs following 60-min exercise, which represented the last common timepoint across groups and conditions. RESULTS: Ageing did not significantly reduce HRV during increasing exercise-heat stress (all p > 0.050). However, T2D and HTN modified HRV during exercise-heat stress such that Detrended Fluctuation Analysis (DFA) α1 (p = 0.012) and the cardiac sympathetic index (p = 0.037) were decreased compared to Older in all except the warmest WBGT condition (32 °C). CONCLUSION: Our unique observations indicate that, relative to their younger counterparts, HRV in healthy older individuals is not perturbed during exercise heat-stress. However, relative to their age-matched healthy counterparts, HRV is reduced during exercise-heat stress in individuals with age-associated chronic conditions, indicative of cardiac autonomic dysfunction.

Cardiac contractile dysfunction, during and following ischaemia, is attenuated by low-dose dietary fish oil in rats.

AIMS: Supplementing animal diets with high-dose fish oil, rich in long chain omega-3 (ω-3) docosahexaenoic acid (DHA), enhances cardiac contractile efficiency and attenuates dysfunction, attributable to ischaemia. However, it remains unclear whether smaller doses, equivalent to what is achievable via regular fish consumption in the human diet, offer similar protection. METHODS: Male Sprague-Dawley (12-15w) rats were fed isoenergetic diets (ad libitum) containing 10% fat by weight (22% energy) for 4-5w. Control diet (CON) contained 5.5% beef tallow; 2.5% ω-6 sunflower seed oil; 2% olive oil. Fish oil diets included high-DHA tuna oil exchanged for olive oil to provide 0.32% (FO1; human equivalent EPA + DHA 570 mg/d) or 1.25% (FO2; equivalent EPA + DHA 2.3 g/d) wt/wt dose of fish oil. Anaesthetised rats (pentobarbital: 60 mg/kg i.p.) were subjected to 45 min coronary artery occlusion then reperfusion in vivo as a whole animal model of regional myocardial ischaemia, with left ventricular haemodynamic function measured by conductance catheter. RESULTS: Ischaemia-induced reductions in rate pressure product recovered faster in the FO2 group and post-ischaemic left ventricular pressure-volume loop integrity (shifted downwards and right in CON) was partially protected in both fish oil groups. CONCLUSION: Ischaemia-induced contractile dysfunction in rats is limited from fish oil doses equivalent to regular consumption of fish in the human diet. These observations highlight plausible and clinically relevant physiological changes that rationalise nutritional conditioning of the heart with DHA for on-going cardioprotection.

Scaling the peak and steady-state aerobic power of running and walking humans.

PURPOSE: The first aim of this experiment was to evaluate the appropriateness of linear and non-linear (allometric) models to scale peak aerobic power (oxygen consumption) against body mass. The possibilities that oxygen consumption would scale allometrically across the complete metabolic range, and that the scaling exponents would differ significantly between basal and maximal-exercise states, were then evaluated. It was further hypothesised that the scaling exponent would increase in a stepwise manner with elevations in exercise intensity. Finally, the utility of applying the scaling exponent derived for peak aerobic power to another population sample was evaluated. METHODS: Basal, steady-state walking and peak (treadmill) oxygen-consumption data were measured using 60 relatively homogeneous men (18-40 year; 56.0-117.1 kg), recruited across five mass classes. Linear and allometric regressions were applied, with the utility of each scaling method evaluated. RESULTS: Oxygen consumption scaled allometrically with body mass across the complete metabolic range, and was always superior to both ratiometric analysis and linear regression. The scaling exponent increased significantly from rest (mass0.57) to maximal exercise (mass0.75; P < 0.05), but not between steady-state walking (mass0.87) and maximal exercise (P > 0.05). When used with an historical database, the maximal-exercise exponent successfully removed the mass bias. CONCLUSION: It has been demonstrated that the oxygen consumption of healthy humans scales allometrically with body mass across the entire metabolic range. Moreover, only two scaling exponents (rest and exercise) were required to produce mass-independent outcomes from those data. Accordingly, ratiometric and linear regression analyses are not recommended as scaling methods.

The Influence of Long-Chain Omega-3 Fatty Acids on Eccentric Exercise-Induced Delayed Muscle Soreness: Reported Outcomes Are Compromised by Study Design Issues.

Delayed onset muscle soreness (DOMS) following eccentric exercise is associated with increased inflammation which can be debilitating. Incorporation of long-chain omega-3 polyunsaturated fatty acids (LC n-3 PUFA), eicosapentaenoic acid, and docosahexaenoic acid into membrane phospholipids provides anti-inflammatory, proresolving, and analgesic effects. This systematic review aims to examine both the quality of studies and the evidence for LC n-3 PUFA in the attenuation of DOMS and inflammation following eccentric exercise, both which of course are empirically linked. The Scopus, Embase, and Web of Science electronic databases were searched to identify studies that supplemented fish oil for a duration of ≥7 days, which included DOMS outcomes following an eccentric exercise protocol. Fifteen (n = 15) studies met inclusion criteria. Eccentric exercise protocols varied from single to multijoint activities. Risk of bias, assessed using either the Cochrane Collaboration tool or the Risk of Bias in Nonrandomized Studies of Interventions tool, was judged as "unclear" or "medium," respectively, for the majority of outcomes. Furthermore, a custom 5-point quality assessment scale demonstrated that only one (n = 1) study satisfied current recommendations for investigating LC n-3 PUFA. In combination, this highlights widespread inappropriate design protocols among studies investigating the role of LC n-3 PUFA in eccentric exercise. Notwithstanding these issues, LC n-3 PUFA supplementation appears to have favorable effects on eccentric exercise-induced DOMS and inflammatory markers. However, the optimal LC n-3 PUFA supplemental dose, duration, and fatty acid composition will only become clear when study design issues are rectified and underpinned by appropriate hypotheses.

A pilot study using a small-sided games program to modify cardiovascular health in sedentary Indigenous men.

ISSUES ADDRESSED: To determine cardiovascular health benefits in Indigenous men following short-duration small-sided games. METHODS: Fourteen sedentary Indigenous males (35.6 SD 7.2 years), randomly assigned to a small-sided games (SSG) or a non-exercising control. Small-sided 20-minute (4 × 5 minute bouts) games of touch football were played 2 x/week for 9 weeks. Waist and hip circumferences, height, total body mass (kg), fat (%), fat free mass (kg), muscle mass (kg), resting heart rate (bpm), systolic blood pressure (mmHg), total cholesterol and high-density lipid concentrations were measured and waist-hip ratios, body mass index (BMI), heart rate variability (HRV), metabolic age and Framingham risk calculated before and after the exercise intervention. Between group differences were examined using unpaired t tests (welch corrected) and described using Cohen's effect size (ES) differences (corrected to determine hedges g). RESULTS: Significant between group differences favouring the SSG group were observed in body mass (P = .039, ES = 0.18), BMI (P = .031, ES = 0.22) and metabolic age (P = .033, ES = 0.29) and in HRV parameters of approximate entropy (ApEN; P = .01, ES = 1.65) and sample entropy (SampEN; P = .0193, ES = 1.40). CONCLUSION: Middle-aged Indigenous men can gain cardiovascular health benefits following short bouts of small-sided game play accumulating in 40-minutes of exercise each week. SO WHAT?: Short-duration SSG may address many exercise barriers, and offer a sustainable form of exercise to improve cardiovascular health amongst Indigenous men.

Cardiac Arrhythmia Prevention in Ischemia and Reperfusion by Low-Dose Dietary Fish Oil Supplementation in Rats.

BACKGROUND: Supplementing animal diets with fish oil increases myocardial omega-3 polyunsaturated fatty acids [ω-3 (n-3) PUFA], lowers heart rate, and prevents malignant cardiac arrhythmias. In contrast to epidemiological reports, results of some human clinical trials and of unphysiologically high doses employed in animal studies call into question the application of dietary ω-3 PUFA for cardioprotection. OBJECTIVE: This study tested the hypothesis that low ω-3 PUFA dietary thresholds for myocardial incorporation in rats, equivalent in dose to what humans derive from eating fish, can reduce heart rate and arrhythmia vulnerability. METHODS: Male Sprague-Dawley rats (12-15 wk old) were fed isoenergetic diets containing 10% fat for 4-5 wk. The control diet (CON) contained 5.5% beef tallow, 2.5% sunflower seed oil, and 2% olive oil. Fish oil diets contained high-DHA tuna oil, exchanged for olive oil: 0.31% [fish oil group 1 (FO1)] (human equivalent EPA + DHA 570 mg/d); 1.25% [fish oil group 2 (FO2)] (equivalent EPA + DHA 2.3 g/d). Anaesthetized rats (pentobarbital, 60 mg/kg intraperitoneally) were subjected in vivo to 15-min cardiac ischemia by left coronary artery occlusion and then reperfusion, with arrhythmias detected by electrocardiogram. RESULTS: Fish oil dose dependently modulated myocardial membrane fatty acids (DHA mean ± SEM: CON, 5.0 ± 0.2%; FO1, 13.1 ± 0.9%; FO2, 18.3 ± 0.4%; n = 4-5; P-trend < 0.001 ANOVA); resting heart rate (CON, 453 ± 6; FO1, 432 ± 4; FO2, 422 ± 5 bpm; n = 15-18; P-trend < 0.001); reduced ventricular fibrillation (VF) (CON, 89%; FO1, 60%; P = 0.052; FO2, 50%; n = 15-18; P = 0.013 chi square); and total arrhythmia severity (arrhythmia score: CON, 6.1 ± 0.4; FO1, 4.6 ± 0.5; FO2, 3.1 ± 0.7; n = 15-18; P-trend < 0.01) during ischemia and reperfusion (VF: Con, 86%; FO1, 22% P = 0.011; FO2, 8% P = 0.001; n = 7-12); (arrhythmia score: CON, 4.6 ± 0.3; FO1, 3.1 ± 0.3; FO2, 1.3 ± 0.3; n = 7-12; P-trend < 0.001). CONCLUSIONS: Ventricular arrhythmias were prevented and heart rate was slowed by lower ω-3 PUFA intake in rats than previously reported, equivalent to human fish consumption and associated with increased myocardial DHA. The efficacy of low-dose fish oil demonstrates biological plausibility for nutritional ω-3 fatty acid-mediated cardioprotection and suggests that effectiveness in human clinical trials may be obscured by failure to exclude fish eaters.

Hyperthermia and dehydration: their independent and combined influences on physiological function during rest and exercise.

PURPOSE: This experiment was designed to quantify the independent and combined influences of hyperthermia and dehydration on effector control during rest and exercise. METHODS: To achieve that, whole-body hydration of healthy adults (N = 8) was manipulated into each of three states (euhydrated, 3% and 5% dehydrated), and then clamped within each of two thermal states (normothermia [mean body temperature: 36.1 °C] and moderate hyperthermia [mean body temperature: 38.2 °C]). Those treatment combinations provided six levels of physiological strain, with resting physiological data collected at each level. The effects of isothermal, thermally unclamped and incremental exercise were then investigated in normothermic individuals during each level of hydration. RESULTS: At rest, dehydration alone reduced urine flows by 83% (3% dehydrated) and 93% (5% dehydrated), while the reduction accompanying euhydrated hyperthermia was 86%. The sensitivities of renal water conservation to 3% dehydration (-21% mOsm-1 kg H2O-1) and moderate hyperthermia (-40% °C-1) were independent and powerful. Evidence was found for different renal mechanisms governing water conservation between those treatments. Cutaneous vasomotor and central cardiac responses were unresponsive to dehydration, but highly sensitive to passive thermal stress. Dehydration did not impair either whole-body or regional sweating during rest or exercise, and not even during incremental cycling to volitional exhaustion. CONCLUSION: In all instances, the physiological impact of these thermal- and hydration-state stresses was independently expressed, with no evidence of interactive influences. Renal water-conservation was independently and powerfully modified, exposing possible between-treatment differences in sodium reabsorption.

The fibro-adipose structure of the female breast: A dissection study.

A paucity of dissection evidence and quantitative data exists to base anatomical descriptions and illustrations of the fibro-adipose structure of the female breast. The aim of this study was to dissect and provide quantitative data of the fibro-adipose structure of the female breast. The fibro-adipose structure of female embalmed breasts were dissected in the coronal (n = 15) and sagittal planes (n = 3). Quantitative data of breast volume, surface area, fibro-adipose pocket number, size and regional variation were collected. Pearson's correlations were used to investigate pocket number and size with breast volume and surface area. Regional variation in pocket number and size were compared using T tests. Throughout the dissection, photographic evidence was collected to support detailed anatomical descriptions. The mean (SD; range) number of pockets located in the superficial region of the breast was 199 ± 53 (108-306) and the mean pocket surface area was 0.88 ± 0.37 cm2 (0.31-1.97). A strong correlation was found between mean pocket number and breast surface area (r2 = 0.8064) and a very weak correlation between mean individual pocket surface area and breast surface area (r2 = -0.1427; P < 0.01). The pockets located anterior to the corpus mamma were significantly larger and less in number (P < 0.05) than those located posterior. The fibro-adipose structure of the female breast is formed by complex scaffolding, consisting of layers of fibrous tissue pockets embedded with adipose tissue which surrounds the corpus mamma and is firmly attached to the perimeter of the breast. Detailed descriptions are supported by quantitative data and photographic evidence. Clin. Anat. 32:146-155, 2019. © 2019 Wiley Periodicals, Inc.

Thermogenic and psychogenic sweating in humans: Identifying eccrine glandular recruitment patterns from glabrous and non-glabrous skin surfaces.

In this experiment, psychogenic (mental arithmetic), thermogenic (mean body temperature elevation of 0.6 °C) and combined thermo-psychogenic treatments were used to explore eccrine sweat-gland recruitment from glabrous (volar hand and forehead) and non-glabrous skin surfaces (chest). It was hypothesised that each treatment would activate the same glands, and that glandular activity would be intermittent. Nine individuals participated in a single trial with normothermic and mildly hyperthermic phases. When normothermic, a 10-min arithmetical challenge was administered, during which sudomotor activity was recorded. Following passive heating and thermal clamping, sweating responses were again evaluated (10 min). A second arithmetical challenge (10 min) was administered during clamped hyperthermia, with its sudorific impact recorded. The activity of individual sweat glands was recorded at 60-s intervals, using precisely positioned, and uniformly applied, starch-iodide papers. Those imprints were digitised and analysed. Peak activity typically occurred during the thermo-psychogenic treatment, revealing physiologically active densities of 128 (volar hand), 165 (forehead) and 77 glands.cm-2 (chest). Except for the hand (46%), glands uniquely activated by one treatment were consistently <10% of the total glands identified. Glandular activations were most commonly of an intermittent nature, particularly during the thermogenic treatment. Accordingly, we accepted the hypothesis that psychogenic, thermogenic and thermo-psychogenic stimuli activate the same sweat glands in both the glabrous and non-glabrous regions. In addition, this investigation has provided detailed descriptions of the intermittent nature of sweat-gland activity, revealing that a consistent proportion of the physiologically active glands are recruited during these thermal and non-thermal stimuli.

A vascular mechanism to explain thermally mediated variations in deep-body cooling rates during the immersion of profoundly hyperthermic individuals.

NEW FINDINGS: What is the central question of this study? Does the cold-water immersion (14°C) of profoundly hyperthermic individuals induce reductions in cutaneous and limb blood flow of sufficient magnitude to impair heat loss relative to the size of the thermal gradient? What is the main finding and its importance? The temperate-water cooling (26°C) of profoundly hyperthermic individuals was found to be rapid and reproducible. A vascular mechanism accounted for that outcome, with temperature-dependent differences in cutaneous and limb blood flows observed during cooling. Decisions relating to cooling strategies must be based upon deep-body temperature measurements that have response dynamics consistent with the urgency for cooling. ABSTRACT: Physiologically trivial time differences for cooling the intrathoracic viscera of hyperthermic individuals have been reported between cold- and temperate-water immersion treatments. One explanation for that observation is reduced convective heat delivery to the skin during cold immersion, and this study was designed to test both the validity of that observation, and its underlying hypothesis. Eight healthy men participated in four head-out water immersions: two when normothermic, and two after exercise-induced, moderate-to-profound hyperthermia. Two water temperatures were used within each thermal state: temperate (26°C) and cold (14°C). Tissue temperatures were measured at three deep-body sites (oesophagus, auditory canal and rectum) and eight skin surfaces, with cutaneous vascular responses simultaneously evaluated from both forearms (laser-Doppler flowmetry and venous-occlusion plethysmography). During the cold immersion of normothermic individuals, oesophageal temperature decreased relative to baseline (-0.31°C over 20 min; P < 0.05), whilst rectal temperature increased (0.20°C; P < 0.05). When rendered hyperthermic, oesophageal (-0.75°C) and rectal temperatures decreased (-0.05°C) during the transition period (<8.5 min, mostly in air at 22°C), with the former dropping to 37.5°C only 54 s faster when immersed in cold rather than in temperate water (P < 0.05). Minimal cutaneous vasoconstriction occurred during either normothermic immersion, whereas pronounced constriction was evident during both immersions when subjects were hyperthermic, with the colder water eliciting a greater vascular response (P < 0.05). It was concluded that the rapid intrathoracic cooling of asymptomatic, hyperthermic individuals in temperate water was a reproducible phenomenon, with slower than expected cooling in cold water brought about by stronger cutaneous vasoconstriction that reduced convective heat delivery to the periphery.

DHA-rich Fish Oil Increases the Omega-3 Index and Lowers the Oxygen Cost of Physiologically Stressful Cycling in Trained Individuals.

Dietary fish oil, providing docosahexaenoic acid (DHA) modulates oxygen consumption and fatigue in animal models. However, in humans predominately supplemented with high eicosapentaenoic acid (EPA), there is no evidence of endurance performance enhancement. Therefore, this study examined if DHA-rich fish oil could improve repeated bouts of physiologically stressful cycling and a subsequent time trial in a state of fatigue. Twenty-six trained males took part in a double-blind study and were supplemented with either 2 × 1g/day soy oil, Control) or DHA-rich tuna fish oil (Nu-Mega) (FO) (560mg DHA / 140mg eicosapentaenoic acid (EPA), for 8 weeks. Maximal cycling power (3 × 6s), isometric quadriceps strength (MVC), Wingate cycling protocol (6 × 30s) and a 5min cycling time-trial were assessed at baseline and eight weeks. The Omega-3 Index was not different at baseline (Control: 4.2 ± 0.2; FO: 4.7 ± 0.2%) and increased in the FO group after eight weeks (Control: 3.9 ± 0.2; FO: 6.3 ± 0.3%, p < .01). There was no effect of DHA-rich fish oil on power output of maximal 6s cycle sprinting (Control: Pre 1100 ± 49 Post 1067 ± 51; FO: Pre 1070 ± 46 Post 1042 ± 46W), during 5min time trail (Control: Pre 267 ± 19 Post 278 ± 20; FO: Pre 253 ± 16 Post 265 ± 16 W) or maximal voluntary contraction force (Control: Pre 273 ± 19 Post 251 ± 19; FO: Pre 287 ± 17 Post 283 ± 16 Nm). Nevertheless, relative oxygen consumption was reduced the FO group during the cycling time trial (Control: -23 ± 26; FO: -154 ± 59ml O2/min/100W p < .05) suggesting improved economy of cycling. We conclude that DHA-rich fish oil, successful at elevating the Omega-3 Index, and reflective of skeletal muscle membrane incorporation, can modulate oxygen consumption during intense exercise.

The effects of thoracic load carriage on maximal ambulatory work tolerance and acceptable work durations.

PURPOSE: Torso loads restrict chest-wall movement and ventilation, particularly during heavy exercise. Therefore, the differential impact of load carriage and chest-wall restriction was investigated during progressive treadmill exercise. In addition, acceptable work durations were derived across a wide range of submaximal, loaded exercise intensities. METHODS: Twelve males participated in two research phases. Phase 1: Three incremental treadmill tests until exhaustion [control (clothing only), load carriage (clothing plus 22-kg vest), and clothing with chest strapping]. Phase 2: Five steady-state exercise trials (clothing plus 22-kg vest) at intensities from 30 to 80 % of peak aerobic power to determine maximal acceptable work durations. RESULTS: Maximal work tolerance [control 17.21 min (±0.93); loaded 13.44 min (±0.68); strapped 17.00 min (±0.83)] and the mass-specific peak aerobic power [control 61.61 mL kg(-1) min(-1) (±2.28); loaded 45.42 mL kg(-1) min(-1) (±1.41); strapped 59.99 mL kg(-1) min(-1) (±1.61)] were reduced only when loaded (P < 0.05). Peak minute ventilation was retained, although loading and chest strapping reduced the breathing reserve. The lower and upper acceptable work duration derivations when working at the 30 % intensity were 133.40 min (±23.77) and 220.10 min (±48.69), but at 80 % intensity, both durations were reduced to <7 min. CONCLUSION: Thoracic loading significantly reduced exercise tolerance and the breathing reserve, but did not modify peak minute ventilation or the absolute peak aerobic power. Chest strapping, as used herein, exerted minimal impact. However, the projected maximal acceptable work durations were much less than derived using previously published methods.

Vegetarian and Omnivorous Nutrition - Comparing Physical Performance.

Humans consuming vegetarian-based diets are observed to have reduced relative risk for many chronic diseases. Similarly, regular physical activity has also been shown to assist in preventing, and reducing the severity of these conditions. Many people, including athletes, acknowledge these findings and are adopting a vegetarian-based diet to improve their health status. Furthermore, athletes are incorporating this approach with the specific aim of optimizing physical performance. To examine the evidence for the relationship between consuming a predominately vegetarian-based diet and improved physical performance, a systematic literature review was performed using the SCOPUS database. No date parameters were set. The keywords vegetarian OR vegan AND sport OR athlete OR training OR performance OR endurance were used to identify relevant literature. Included studies (i) directly compared a vegetarian-based diet to an omnivorous/mixed diet, (ii) directly assessed physical performance, not biomarkers of physical performance, and (iii) did not use supplementation emulating a vegetarian diet. Reference lists were hand searched for additional studies. Seven randomized controlled trials and one cross-sectional study met the inclusion criteria. No distinguished differences between vegetarian-based diets and omnivorous mixed diets were identified when physical performance was compared. Consuming a predominately vegetarian-based diet did not improve nor hinder performance in athletes. However, with only 8 studies identified, with substantial variability among the studies' experimental designs, aims and outcomes, further research is warranted.

The utility of heart rate and minute ventilation as predictors of whole-body metabolic rate during occupational simulations involving load carriage.

The utility of cardiac and ventilatory predictors of metabolic rate derived under temperate and heated laboratory conditions was evaluated during three fire-fighting simulations (70-mm hose drag, Hazmat recovery, bushfire hose drag; N = 16 per simulation). The limits of agreement for cardiac (temperate: - 0.54 to 1.77; heated: - 1.39 to 0.80 l min(- 1)) and ventilatory surrogates (temperate: - 0.19 to 1.27; heated: - 0.26 to 1.16 l min(- 1)) revealed an over-estimation of oxygen consumption that exceeded the acceptable limits required by occupational physiologists (N = 25; ± 0.24 l min(- 1)). Although ventilatory predictions offered superior precision during low-intensity work (P < 0.05), a cardiac prediction was superior during more demanding work (P < 0.05). Deriving those equations under heated conditions failed to improve precision, with the exception of the cardiac surrogate during low-intensity work (P < 0.05). These observations imply that individualised prediction curves are necessary for valid estimations of metabolic demand in the field.

Physiological cross-sectional area of the oblique head of the adductor pollicis is greater than its transverse counterpart: implications for functional testing.

INTRODUCTION: Despite structural distinction between the transverse and oblique heads of the adductor pollicis, in vivo testing continues to consider the adductor pollicis as functionally simplistic. As a muscle's architecture is a strong indicator of function, in this study we aimed to determine whether the physiological cross-sectional areas (PCSAs) of both heads were uniform. METHODS: Classical, microdissection, and chemical dissection procedures were conducted on 10 cadaveric left hands to determine structural origin and insertions. Architectural measures of muscle length (Lm ), muscle weight (Wm ), fascicle length (Lf ), sarcomere length (Ls ), and pennation angle (θ) were used to calculate PCSA and fascicle length:muscle length ratio (Lf :Lm ). RESULTS: The oblique head had greater variation in attachments, significantly greater PCSA (P = 0.008), and smaller Lf :Lm (P = 0.001) than its transverse counterpart. CONCLUSIONS: Muscle architecture suggests the oblique head has greater potential for force generation, and the transverse has greater potential for joint excursion.

Long-chain n-3 DHA reduces the extent of skeletal muscle fatigue in the rat in vivo hindlimb model.

Dietary fish oil modifies skeletal muscle membrane fatty acid composition and oxygen efficiency similar to changes in the myocardium. Oxygen efficiency is a key determinant of sustained force in mammalian skeletal muscle. Therefore, in the present study, we tested the effects of a fish-oil diet on skeletal muscle fatigue under the stress of contraction using the rat in vivo autologous perfused hindlimb model. For 8 weeks, male Wistar rats were fed a diet rich in saturated fat (SF), a diet rich in n-6 PUFA or a diet rich in long-chain (LC) n-3 PUFA DHA derived from fish oil. In anaesthetised, mechanically ventilated rats, with their hindlimbs perfused with arterial blood at a constant flow, the gastrocnemius-plantaris-soleus muscle bundle was stimulated via sciatic nerve (2 Hz, 6-12 V, 0·05 ms) to contract repetitively for 30 min. Rats fed the n-3 PUFA diet developed higher maximum twitch tension than those fed the SF and n-6 PUFA diets (P< 0·05) and sustained twitch tension through more repetitions before the tension declined to 50 % of the maximum twitch tension (P< 0·05). The n-3 PUFA group used less oxygen for tension developed and produced higher venous lactate concentrations with no difference in glycogen utilisation compared with the SF and n-6 PUFA groups. These results further support that incorporation of DHA into skeletal muscle membranes increases the efficiency of oxygen use over a range of contractile force and this is expressed as a higher sustained force and prolonged time to fatigue.