Occupational health screening during Gurkha Central Selection: a retrospective cohort study.

OBJECTIVE: The selection process to the British Army's Brigade of Gurkhas is rigorous, demanding and competitive. The ethos of recruitment to the Gurkhas is grounded in an overarching tenant: that selection is free, fair and transparent. The aim of this study was to retrospectively review reasons for potential recruits (PRs) to be deemed medically unsuitable or deferred suitability on medical grounds for selection to the Brigade of Gurkhas. METHODS: A retrospective review was conducted by extracted data from published post-exercise reports for the past four years to ascertain numbers of PRs deemed medically fit, medically unsuitable or deferred suitability on medical grounds. The International Classification of Disease version 11 (ICD-11) codes were retrospectively assigned to code medical reasons for non-progression. Rates of medical non-progression were compared by year. RESULTS: A total of 3154 PRs were analysed between 2018 and 2021. There was no significant difference between PRs deemed medically fit and those deemed medically suitable or deferred on medical grounds over the study period (p=0.351). There was a significant difference in the ratio of PRs deferred on medical grounds and those deemed medically unsuitable over the study period (p<0.05). CONCLUSION: Selection to the Gurkhas is extremely competitive. These data demonstrate that, overall, reasons for medical deferral or unsuitability have remained constant despite the impact of a global pandemic. These data reinforce the central tenant of Gurkha selection; that it continues to be free, fair, and transparent.

Do athletic ECG changes predict athletic performance in Gurkha recruits?

INTRODUCTION: ECG changes are associated with regular long-term intensive exercise due to electrical manifestations of increased vagal tone, increased ventricular wall thickness and enlarged chamber size. The aim of this study was to further understand the relationship of athletic ECG changes and athletic performance in an athletic population. METHODS: A retrospective cohort study was performed in 195 Nepali civilian males undergoing selection to the Gurkhas. V̇O2max (maximal oxygen consumption) was estimated from a 1.5-mile run time using Cooper's formula and correlated with athletic ECG adaptations. Variables were explored with univariable and multivariable linear regression. RESULTS: The median number of athletic changes on ECG was 2 (IQR 1-2). There was no significant correlation (p=0.46) between the number of ECG adaptations and the degree of cardiovascular fitness by estimated V̇O2max (estV̇O2max). We found a negligible but significant correlation between the presence of inferior T wave inversion (TWI) and estV̇O2max (R2=0.03, p=0.02). The multivariable-fitted regression model was: estV̇O2max~Intercept+presence of RVH (right ventricular hypertrophy) voltage criteria+absence of sinus arrhythmia+T wave axis+inferior TWI. The overall regression was statistically significant: R2=0.10, F(df=4, df=189)=[5.4], p=0.0004). All variables in the multivariable model significantly predicted estV̇O2max (p<0.04). CONCLUSION: ECG changes of athleticism negligibly predict and differentiate athletic performance in our athletic population. The most predictive ECG markers being voltage criteria for left ventricular hypertrophy and RVH. Markers of increased vagal tone were not predictive. TWI, being a marker for disease, was also a marker for athletic performance in this cohort. The number of athletic ECG adaptations did not predict increased athletic performance.

Assessment of salivary cortisol dynamics in an infantry training exercise: a pilot study.

INTRODUCTION: Measuring cortisol during military training offers insights into physiological responses to stress. We attempted precisely timed, cortisol awakening response (CAR) and pre-sleep cortisol (PSC), and diurnal slope (peak morning minus evening cortisol), during a British Army exercise. We aimed to understand cortisol dynamics and evaluate the feasibility of CAR and PSC in this environment. METHOD: Setting: high-intensity, 10-day infantry exercise. Participants: regular infantry soldiers exercising (EX, n=25) or headquarters-based (HQ, n=6). Participants undertook PSC and WAKE and WAKE+30 min samples after 1-2 days, 5-6 days and 9-10 days. Wrist-worn GENEActiv accelerometers were used to assess sleep duration in EX only. Samples taken ±15 min from prespecified time points were deemed adherent. Validated questionnaires were used to measure resilience and perceived stress. Cortisol and cortisone were measured simultaneously by liquid chromatography tandem mass spectrometry. RESULTS: From adherent participants' samples, CAR was positive and tended to decrease as the exercise progressed. From all available data, HQ demonstrated greater diurnal slope than EX (F=7.68, p=0.02), reflecting higher morning cortisol (F=4.72, p=0.038) and lower PSC (p=0.04). No differences were seen in cortisol:cortisone ratio. 26.1% of CAR samples were adherent, with moderately strong associations between adherence and stress (r=0.41, p=0.009) but no association between adherence and day of exercise (χ2=0.27, p=0.8), sleep duration (r=-0.112, p=0.43) or resilience (r=-0.79, p=0.75). Test-retest reliability ratings for CAR were Cronbach's α of 0.48, -11.7 and 0.34 for the beginning, middle and end of the exercise, respectively. CONCLUSIONS: We observed a reduction in morning cortisol and decreased diurnal slope during a high-intensity military exercise, compared with the HQ comparator cohort in whom diurnal slope was preserved. A carefully timed CAR was not feasible in this setting.

Histamine, mast cell tryptase and post-exercise hypotension in healthy and collapsed marathon runners.

PURPOSE: Heat stress exacerbates post-exercise hypotension (PEH) and cardiovascular disturbances from elevated body temperature may contribute to exertion-related incapacity. Mast cell degranulation and muscle mass are possible modifiers, though these hypotheses lack practical evidence. This study had three aims: (1) to characterise pre-post-responses in histamine and mast cell tryptase (MCT), (2) to investigate relationships between whole body muscle mass (WBMM) and changes in blood pressure post-marathon, (3) to identify any differences in incapacitated runners. METHODS: 24 recreational runners were recruited and successfully completed the 2019 Brighton Marathon (COMPLETION). WBMM was measured at baseline. A further eight participants were recruited from incapacitated runners (COLLAPSE). Histamine, MCT, blood pressure, heart rate, body temperature and echocardiographic measures were taken before and after exercise (COMPLETION) and upon incapacitation (COLLAPSE). RESULTS: In completion, MCT increased by nearly 50% from baseline (p = 0.0049), whereas histamine and body temperature did not vary (p > 0.946). Systolic (SBP), diastolic (DBP) and mean (MAP) arterial blood pressures and systemic vascular resistance (SVR) declined (p < 0.019). WBMM negatively correlated with Δ SBP (r = - 0.43, p = 0.046). For collapse versus completion, there were significant elevations in MCT (1.77 ± 0.25 µg/L vs 1.18 ± 0.43 µg/L, p = 0.001) and body temperature (39.8 ± 1.3 °C vs 36.2 ± 0.8 °C, p < 0.0001) with a non-significant rise in histamine (9.6 ± 17.9 µg/L vs 13.7 ± 33.9 µg/L, p = 0.107) and significantly lower MAP, DBP and SVR (p < 0.033). CONCLUSION: These data support the hypothesis that mast cell degranulation is a vasodilatory mechanism underlying PEH and exercise associated collapse. The magnitude of PEH is inversely proportional to the muscle mass and enhanced by concomitant body heating.

The use of routine blood tests to assist the diagnosis of COVID-19 in symptomatic hospitalized patients.

INTRODUCTION: Specific patterns of blood test results are associated with COVID-19 infection. The aim of this study was to identify which blood tests could be used to assist in diagnosing COVID-19. METHOD: A retrospective review was performed on consecutive patients referred to hospital with a clinical suspicion of COVID-19 over a period of four weeks. The patient's clinical presentation and severe acute respiratory syndrome coronavirus 2 reverse-transcription polymerase chain reaction (SARS-CoV-2 RT-PCR) were recorded. The patients were divided by diagnosis into COVID (COVID-19 infection) or CONTROL (an alternate diagnosis). A retrospective review of consecutive patients over a further two-week period was used for the purposes of validation. RESULTS: Overall, 399 patients (53% COVID, 47% CONTROL) were analysed. White cell count, neutrophils and lymphocytes were significantly lower, while lactate dehydrogenase and ferritin were significantly higher, in the COVID group in comparison to CONTROL. Combining the white cell count, lymphocytes and ferritin results into a COVID Combined Blood Test (CCBT) had an area under the curve of 0.79. Using a threshold CCBT of -0.8 resulted in a sensitivity of 0.85 and a specificity of 0.63. Analysing this against a further retrospective review of 181 suspected COVID-19 patients, using the same CCBT threshold, resulted in a sensitivity of 0.73 and a specificity of 0.75. The sensitivity was comparable to the SARS-CoV-2 RT PCR. DISCUSSION: Mathematically combining the blood tests has the potential to assist clinical acumen allowing for rapid streaming and more accurate patient flow pending definitive diagnosis. This may be of particular use in low-resource settings.