New Zealand blackcurrant extract improves high-intensity intermittent running performance.

New Zealand blackcurrant (BC) intake showed reduced blood lactate during low and moderate intensity cycling and improved 16.1 km cycling time trial performance. We examined the effect of BC on high-intensity intermittent treadmill running and post-running lactate clearance. Thirteen active males (age: 25±4 yrs, stature: 1.82±0.07 m, body mass: 81±14 kg, V̇O2max: 56±4 mL∙kg-1∙min-1, velocity at V̇O2max: 17.6±0.8 km∙h-1, mean±SD) visited the laboratory three times. In the 1st visit, a ramp protocol (0.1 km∙h-1 every 5 sec) was completed to establish V̇O2max and velocity at V̇O2max, and subjects were familiarised with the protocols. In visits 2 and 3, subjects completed an high intensity intermittent running capability test which consisted of six 19 s high-intensity running bouts, each interspersed by 15 s of low-intensity running, followed by 1 minute of rest, this was repeated at increasing speeds, until exhaustion. Prior to visits 2 and 3, subjects consumed either New Zealand BC extract (300 mg∙day-1 CurraNZ™; containing 105 mg anthocyanin) or placebo (P) (300 mg∙day-1 microcrystalline cellulose M102) for 7 days in capsules (double blind, randomised, cross-over design, wash-out at least 14 days). Blood lactate was collected for 30 min post-exhaustion. Two-tailed paired t-tests were used and significance accepted at p< .05. BC increased total running distance by 10.6% (BC: 4282±833 m, P: 3871±622 m, p = .023, 10 out of 13 subjects improved), with the distance during the high-intensity running bouts by 10.8% (p= .024). Heart rate, rating of perceived exertion and oxygen uptake were not different between conditions for each stage. At exhaustion, lactate tended to be higher for BC (BC: 6.01±1.07 mmol∙L-1, P: 5.22±1.52 mmol∙L-1, p = .066, 9 out of 13 subjects). There was a trend towards improved lactate clearance following 15 min (BC: -2.89±0.51 mmol∙L-1, P: -2.46±0.39 mmol∙L-1, p = .07) and 30 minutes of passive recovery (BC: -4.12±0.73 mmol∙L-1, P: -3.66±1.01 mmol∙L-1, p = 0.11). It is concluded that New Zealand blackcurrant extract (CurraNZ™) may enhance performance in team sports characterised by high-intensity intermittent exercise as with BC intake greater distances were covered during high-intensity running, there was higher lactate tolerance, and increased lactate clearance after high-intensity exercise

The importance of left atrial volume assessment in identifying the cause of ischemic stroke

Separating cardioembolic from large artery stroke has important treatment implications. We investigated whether echocardiography could improve Cardioembolic Stroke (CES) prediction compared with traditional measures and cholesterol biomarkers. Data from 40 consecutive patients presenting with acute ischemic stroke which included brain and carotid imaging, ECG, echo, serum cholesterol and apolipoproteins were independently reviewed. Patients were classified into two groups: a) CES, defined by sustained or paroxysmal atrial fibrillation and \u3c50% stenosis of a perfusing cerebral artery; b) Large artery stroke (LAS) defined as \u3e 50% stenosis of an ipsilateral perfusing cerebral artery, with no evidence of AF on monitoring or evidence of small artery disease on neuroimaging and confirmed by an independent neurologist. Other than the CES group being older, the baseline characteristics of the two groups were similar. Left Atrial Volume (indexed for body surface area, LAVi) was significantly larger in CES (57.9 +/- 19.4 vs 31.1 +/- 8.3ml/m2, p\u3c0.01), with a simple equation that utilised age, LAVi and E wave accurately predicting 90% of CES. The difference in LAVi for CES was beyond that anticipated from the presence of AF alone. No differences in any of the lipid biomarkers were observed. These finding indicate that LAVi is the most important predictor of CES due to atrial fibrillation and is highly predictive of patients with CES due to atrial fibrillation. Cholesterol biomarkers offered no additional discriminatory value

Validity of energy expenditure estimation methods during 10 days of military training

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-labelled 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 analysed 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 against which the GENEActiv showed near identical average TEE (mean bias ± LoA: -15 ± 851 kcal day ) while Fitbit tended to underestimate (-656 ± 683 kcal·day ) and the PA log substantially overestimate (+1946 ± 1637 kcal·day ). 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

Transferability of Military-Specific Cognitive Research to Military Training and Operations

The influence of acute aerobic exercise on cognitive function is well documented (e.g., Lambourne and Tomporowski, 2010; Chang et al., 2012). However, the influence of military specific exercise on aspects of cognitive function relevant to military operations is less well understood. With the increasing physical and cognitive loads placed on military personnel (Mahoney et al., 2007), this interaction is fundamental to understanding operational performance (Russo et al., 2005). As such, ensuring the transferability of military-specific cognitive research to military training and operations, is of great importance, particularly for the development of both mitigation and enhancement strategies (see Brunyé et al., 2020). Despite this, studies have not always considered whether meaningful translations can be made. We suggest that researchers should endeavor to strike the balance between external validity and experimental control (Figure 1), and consider the concept of representative design (Pinder et al., 2011). External validity refers to the transferability of research findings from the research to the target population, whilst representative design refers to methodological approaches chosen to ensure that the experimental task constraints characterize those experienced during performance (i.e., the training or operational environment) (Pinder et al., 2011). Herein, we will focus on representative design during load carriage investigations, due to its mission criticality (Knapik and Reynolds, 2012), and it being the primary physical activity choice during military specific exercise-cognition research. Specifically, we discuss the inclusion of dual-/multi-tasking, implications of study population, cognitive task selection, and the data collection environment

The Development, and Day-to-Day Variation, of a Military-Specific Auditory N-Back Task and Shoot-/Don’t-Shoot Task

During military operations, soldiers are required to successfully complete numerous physical and cognitive tasks concurrently. Understanding the typical variance in research tools that may be used to provide insight into the interrelationship between physical and cognitive performance is therefore highly important. This study assessed the inter-day variability of two military-specific cognitive assessments; a Military-Specific Auditory N-Back Task (MSANT) and a Shoot-/Don’t-Shoot Task (SDST) in 28 participants. Limits of agreement ± 95% Confidence Intervals, Standard Error of the Mean, and Smallest Detectable Change were calculated to quantify the typical variance in task performance. All parameters within the MSANT and SDST demonstrated no mean difference for trial visit in either the seated or walking condition, with equivalency demonstrated for the majority of comparisons. Collectively, these data provided an indication of the typical variance in MSANT and SDST performance, whilst demonstrating that both assessments can be used during seated and walking conditions

Cognitive, psychophysiological, and perceptual responses to a repeated military-specific load carriage treadmill simulation

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; V̇O2max, 51.5 ± 6.4 mL·kg-1·min-1) completed three ~65-minute bouts of a Fast Load Carriage Protocol (FLCP), each interspersed with a 65-minute 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<0.001, Kendall’s W=69.084) and for time on the accuracy-speed trade-off parameter of the SDST (p=0.025, Ѡ2=0.024) 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<0.001, Ѡ2=0.045; time: p<0.001, Ѡ2=0.232). 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

Association between external training loads and injury incidence during 44 weeks of military training

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 centre. 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 ~2.0–3.5 fold, suggesting that the ratio of workload to recovery is important for mitigating injury occurrence