Re-evaluating the Need for Routine Maximal Aerobic Capacity Testing within Fighter Pilots.

INTRODUCTION: There is a current belief in aviation suggesting that aerobic training may reduce G-tolerance due to potential negative impacts on arterial pressure response. Studies indicate that increasing maximal aerobic capacity (V˙o2 max) through aerobic training does not hinder G-tolerance. Moreover, sustained centrifuge training programs revealed no instances where excessive aerobic exercise compromised a trainee's ability to complete target profiles. The purpose of this review article is to examine the current research in the hope of establishing the need for routine V˙o2-max testing in air force pilot protocols.METHODS: A systematic search of electronic databases including Google Scholar, PubMed, the Aerospace Medical Association, and Military Medicine was conducted. Keywords related to "human performance," "Air Force fighter pilots," "aerobic function," and "maximal aerobic capacity" were used in various combinations. Articles addressing exercise physiology, G-tolerance, physical training, and fighter pilot maneuvers related to human performance were considered. No primary data collection involving human subjects was conducted; therefore, ethical approval was not required.RESULTS: The V˙o2-max test provides essential information regarding a pilot's ability to handle increased Gz-load. It assists in predicting G-induced loss of consciousness by assessing anti-G straining maneuver performance and heart rate variables during increased G-load.DISCUSSION: V˙o2-max testing guides tailored exercise plans, optimizes cardiovascular health, and disproves the notion that aerobic training hampers G-tolerance. Its inclusion in air force protocols could boost readiness, reduce health risks, and refine training for fighter pilots' safety and performance. This evidence-backed approach supports integrating V˙o2-max testing for insights into fitness, risks, and tailored exercise.Zeigler Z, Acevedo AM. Re-evaluating the need for routine maximal aerobic capacity testing within fighter pilots. Aerosp Med Hum Perform. 2024; 95(5):273-277.

Maximal Aerobic Capacity as a Predictor of Performance on ACFT Total Score of ROTC Cadets.

The Army Combat Fitness Test (ACFT) is a newly developed test that assesses the combat readiness of U.S. Army soldiers. The purpose of this cross-sectional study is to determine if VO2max can predict performance outcomes of the ACFT in ROTC cadets. This understanding can provide a better understanding of the aerobic demands of the ACFT. Cadets (50 males, 14 females; aged 21.43 ± 4.10 years) completed the 6-event ACFT (maximum trap-bar deadlift [MDL], standing power throw [SPT], hand-release pushups [HRPU], sprint-drag-carry shuttle run [SDC], plank [PLK], and 2-mile run [2MR]). The cadets conducted a maximal treadmill running test following the Bruce protocol. The ability of VO2max (mL·kg-1·min-1) to predict ACFT performance was determined with a linear regression model. Significance was set at p < 0.05. VO2max was significantly and positively correlated to MDL (r = .253, p = .044), HRPU (r = .486, p < .001), SDC (r = .495, p < .001), PLK (r = .628, p < .001) 2MR (r = .612, p < .001) and overall ACFT score (r = .619, p < .001) but not SPT (r = .203, p = .108). VO2max significantly explained 38% (p < .001) of the variance on the total ACFT scores with a beta coefficient of 4.338. There is a gap in understanding how VO2max impacts performance in the newly implemented ACFT. For every 1 mL·kg-1·min-1 increase in VO2max, ACFT total scores increased by 4 points. These findings support the need for further research due to the trends of U.S. Army personnel failing the 2MR, which can be associated with an insufficient aerobic capacity.

Body Mass Index Superior to Body Adiposity Index in Predicting Adiposity in Female Collegiate Athletes.

Body mass index (BMI) is moderately correlated with %Fat and often used to assess obesity in athletes. Limited research assesses BMI as a surrogate for %Fat in female collegiate athletes. Body Adiposity Index (BAI) is an anthropometric measurement suggested to be superior to BMI at predicting adiposity but has not been well assessed within female athletic populations. This study aimed to determine if BAI is superior to other anthropometric indices to predict %Fat in female collegiate athletes and college-aged female non-athletes. Collegiate female athletes and female non-athletes were invited into the laboratory for anthropometrics and %Fat measurements via BOD POD. BAI was calculated as Hip Circumference/Height1.5 - 18. Eighty-eight female non-athletes and 72 female athletes from soccer (n = 27), softball (n = 28), and basketball (n = 17) completed the study. Using BMI, 19% of non-athletes had a false positive (FP). Sensitivity of BMI in non-athletes was 85.5%, while specificity was 73%. 16% of athletes had a FP. Sensitivity of BMI within athletes was 100%, specificity was 81%. BMI outperformed BAI in athletic (BMI: r = .725, p < .001; BAI: r = .556, p < .001) and nonathletic (BMI: r = .650, p < .001; BAI: r = .499, p < .001) groups. The strongest anthropometric predictor of %Fat within the non-athlete population was BMI (r2 = .42, p < .001). Waist circumference was the strongest predictor in the athletic population (r2 = .62, p < .001). BMI outperformed BAI in its ability to predict %Fat.

Impact of wildland firefighting on arterial stiffness and cardiorespiratory fitness.

The purpose of this study was to assess the effect of wildland firefighting on measures of cardiovascular health. The study was carried out in two parts. Part one assessed relationships between years of wildland firefighting and cardiovascular variables (n = 28). Part two looked at cardiovascular variables pre and post a wildland firefighting season (n = 18). Independent of age, a statistically significant relationship between number of seasons firefighting and VO2max was found (r2=.140, p=.048). A statistically significant reduction in VO2max of -4.1 ± 5.7 ml·kg-1 min-1 was witnessed following fire season (95%CI=-6.9 to -1.3, p=.048). Year to date hazard pay was significantly correlated with ankle-brachial index (r=-.474, p=.040). Wildland firefighters who reported >640 h of hazard pay had a greater VO2max reduction than those reporting less hazard pay (-1.7 ± 5.7 ml·kg-1·min-1 vs. -7.1 ± 4.3 ml·kg-1·min-1, p=.037). Wildland firefighting may negatively impact cardiorespiratory fitness and arterial health.

COVID-19 Self-quarantine and Weight Gain Risk Factors in Adults.

PURPOSE OF REVIEW: The COVID-19 pandemic is associated with weight gain in certain individuals. This review highlights the risk factors for weight gain during COVID-19 self-quarantine in adults. RECENT FINDINGS: Among those who have gained weight during COVID-19 self-quarantine, self-reported body weight has increased between .5 and 1.8 kg (± 2.8 kg) after just 2 months of quarantine. Identified risk factors for weight gain during COVID-19 self-quarantine are the following: increased sedentary behaviors, decreased physical activity, increased snacking frequency (particularly after dinner), increased alcohol intake, decreased water intake, emotional eating, decreased sleep quality, and being overweight/obese. Having identified risk factors for weight gain during the COVID-19 pandemic, practitioners and researchers should devise plans to assist those who have gained weight to re-learn weight management/weight loss strategies.

Differing Impact of Weight Cycling on Ambulatory Blood Pressure versus Conventional Blood Pressure Assessment: A Possible Explanation to Controversy.

BACKGROUND: Weight cycling (WC) is a widespread behavior associated with elevated laboratory blood pressure (BP). The impact WC may have on ambulatory BP (ABP) is unknown. METHODS: Impact of self-reported WC history on ABP was assessed via cross-sectional nonexperimental design. Sixty-five women completed the Weight and Lifestyle Inventory (WALI) questionnaire. The WALI has been shown to be a reliable index of WC (r=0.87, P<0.001). Data were analyzed looking at WC both as a continuous and criterion variable, and subjects were dichotomized as either WC or non-WC (NWC). RESULTS: WC (n=31) were older (39.7±8.9 vs. 33.1±11.3 years), had a higher percent body fat (47.1%±6.2% vs. 41.4%±7.8%), and were less fit (21.2±5.4 vs. 26.7±7.6 mL/kg/min) than NWC (n=34). No significant correlation between laboratory systolic BP (SBP, P=0.830) or diastolic BP (DBP, P=0.997) and WC was observed. A significant correlation between the number of WC and systolic ABP (r=0.326, P=0.010) and trend for diastolic ABP (r=0.238, P=0.065) was found. SBP (23% vs. 17%, P<0.001) and DBP (13% vs. 9%, P<0.001) load was higher for WC compared to NWC women. CONCLUSION: WC may deleteriously affect BP outcomes that might only be observed when ABP monitoring is used.

Fatness and Fluctuating Body Weight: Effect on Central Vasculature.

Weight Cycling (WC) is a prevalent behavior associated with adverse cardiovascular (CV) health. However, a 2010 review on the effects of WC and blood pressure (BP) determined that there was not enough evidence to draw definitive conclusions. Central BP is the principal predictor of CV risk compared to peripheral BP. The influence that WC may have specifically on central BP is unknown. Cross-sectional observation of self-reported history of WC on measures of CV health was undertaken. Seventy-five women completed a Weight and Lifestyle Inventory questionnaire, which is considered a reliable index of WC (r = 0.87, p < 0.001). Measures of visceral fat, BP, arterial stiffness, and VO2peak were taken. Regression equations were used to assess primary predictors of these outcomes. Seventy-five middle aged (39 ± 11 years), obese (32 ± 7 kg/m2), and relatively unfit (24 ± 8 ml·kg-1 min-1) women completed the study. Visceral fat was the strongest predictor of brachial systolic blood pressure (SBP; r2 = 0.283), brachial diastolic blood pressure (DBP; r2 = 0.176), central SBP (r2 = 0.375), and augmentation index (AIx; r2 = 0.535, all p < 0.001). VO2peak was the strongest predictor of central DBP (r2 = 0.062, p = 0.036) and augmentation pressure (AP; r2 = 0.491, p < 0.001). Weight cycling index was associated with visceral fat (r = 0.521, p < 0.001). Visceral fat was a mediator between WC and central SBP (confidence interval [CI] = 0.0053-0.0602), AP (CI = 0.0507-0.4915), AIx (CI = 0.0025-0.0699), and carotid-femoral pulse wave velocity (CI = 0.0115-0.1227; all p < 0.05). WC may increase visceral fat accumulation, which was associated with increased central SBP and measures of arterial stiffness.

Postexercise Hemodynamic Responses in Lean and Obese Men.

PURPOSE: We assessed resting central/peripheral blood pressure (BP), postexercise BP, and hemodynamic responses (stroke volume, cardiac output, and systemic vascular resistance) after acute exercise and 2 wk of aerobic training in lean and centrally obese men matched for BP. METHODS: Eight lean (body mass index < 25 kg·m, visceral fat = 279 ± 224 cm) and eight centrally obese (body mass index > 30 kg·m, visceral fat = 1471 ± 374 cm) men performed six training sessions (3 d·wk for 40 min at 65%-70% HRmax). Resting BP and hemodynamic measurements were obtained at baseline, after exercise for 60 min, and at 24 h and 48 h after the last training session. RESULTS: Postexercise brachial and central systolic BP (SBP) and mean arterial BP decreased 3-4 mm Hg below resting in lean (P < 0.001) and increased by 3 mm Hg in obese (P < 0.02). Posttraining resting brachial/central SBP were reduced by 3-4 mm Hg only in lean men (P < 0.05). Pretraining postexercise hypotension was significantly correlated with the training-induced change in resting brachial SBP at 48 h (r = 0.58, P = 0.02), but not at 24 h (r = 0.38, P = 0.15). Similar correlations were observed between acute reductions in central SBP and central SBP at 24 h (r = 0.43, P = 0.09) and 48 h (r = 0.54, P = 0.03) posttraining. CONCLUSIONS: In contrast to the consistent results for lean men, postexercise hypotension was not observed in centrally obese men, and resting SBP was not reduced after a short aerobic training program. Considerable individual variation in postexercise BP response among obese men may have implications for design of exercise interventions to lower BP in these individuals.

Acute effects on cognitive performance following bouts of standing and light-intensity physical activity in a simulated workplace environment.

OBJECTIVES: To compare acute cognitive effects following bouts of standing (STAND), cycling (CYCLE) and walking (WALK) to a sit-only (SIT) condition. DESIGN: Randomized cross-over full-factorial study. METHODS: Nine overweight (BMI=29±3kg/m2) adults (30±15years; 7 females, 2 males) completed four conditions (SIT, STAND, WALK and CYCLE) across a 6h period with a 7days washout period between conditions. SIT consisted of uninterrupted sitting. Experimental conditions included intermittent bouts of standing (STAND), cycling (CYCLE) and walking (WALK). A cognitive performance battery (Cogstate) was completed twice in a seated position following bouts of standing and light-intensity physical activity. Mixed-effects models compared between-condition differences in standardized score (z-score), accuracy (%), and speed (log10ms). RESULTS: Cognitive performance z-score and accuracy measures were higher during STAND, CYCLE and WALK (P<0.05) conditions compared to the SIT condition. CYCLE was better than other experimental conditions. CONCLUSIONS: Compared to uninterrupted sitting, short bouts of standing or light-intensity cycling and walking may improve acute cognitive performance.

Effects of Standing and Light-Intensity Walking and Cycling on 24-h Glucose.

PURPOSE: This study aimed to compare 24-h and postprandial glucose responses to incremental intervals of standing (STAND), walking (WALK), and cycling (CYCLE) to a sit-only (SIT) condition. METHODS: Nine overweight/obese (body mass index = 29 ± 3 kg·m) adults (30 ± 15 yr) participated in this randomized crossover full-factorial study, with each condition performed 1 wk apart. STAND, CYCLE, and WALK intervals increased from 10 to 30 min·h (2.5 h total) during an 8-h workday. WALK (1.0 mph) and STAND were matched for upright time, and WALK and CYCLE were matched for energy expenditure (~2 METs). Continuous interstitial glucose monitoring was performed for 24 h to include the 8-h workday (LAB), after-work evening hours (EVE), and sleep (SLEEP). Three 2-h postprandial periods were also analyzed. Linear mixed models were used to test for condition differences. RESULTS: Compared with SIT (5.7 ± 1.0 mmol·L), mean 24-h glucose during STAND (5.4 ± 0.9 mmol·L) and WALK (5.3 ± 0.9 mmol·L) were lower, and CYCLE (5.1 ± 1.0 mmol·L) was lower than all other conditions (all P < 0.001). During LAB and EVE, mean glucose was lower for STAND, WALK, and CYCLE compared with SIT (P < 0.001). During SLEEP, the mean glucose for CYCLE was lower than all other conditions (P < 0.001). Compared with SIT, cumulative 6-h postprandial mean glucose was 5%-12% lower (P < 0.001) during STAND, WALK, and CYCLE, and 6-h postprandial glucose integrated area under the curve was 24% lower during WALK (P < 0.05) and 44% lower during CYCLE (P < 0.001). CONCLUSIONS: Replacing sitting with regular intervals of standing or light-intensity activity during an 8-h workday reduces 24-h and postprandial glucose. These effects persist during evening hours, with CYCLE having the largest and most sustained effect.

Acute effects of whole-body vibration with resistance exercise on postexercise blood pressure and oxygen consumption in prehypertensive adults.

BACKGROUND/OBJECTIVE: Research on the acute health effects of whole-body vibration with resistance exercise (WBV + RE) for clinical populations is limited. This randomized crossover trial evaluated postexercise hypotension and excess postexercise oxygen consumption (EPOC) in response to three conditions: WBV + RE, RE alone, and control (CON) in 11 prehypertensive (systolic/diastolic blood pressure: 120-139/80-89 mmHg) adults. METHODS: Following a 12-hour fast with no exercise for the previous 24 hours, resting VO2 and blood pressure (BP) were measured. WBV + RE was performed while standing barefoot on a vibration platform (Pneumex Pro-Vibe) and lifting a bar of 10% body weight. Fifteen repetitions of nine exercises were performed using a 1-minute-to-30-second exercise:rest ratio. RE was identical to WBV + RE but without vibration. During CON, participants remained seated for 15 minutes. Following exercise, VO2 was measured continuously and BP every 15 minutes for 3 hours. RESULTS: Postexercise hypotension and EPOC were significantly different for WBV + RE compared with RE and CON (p <0.001). Postexercise systolic BP was significantly lower for WBV + RE as compared with RE or CON, while diastolic BP was lower for both WBV + RE and RE compared with CON (p < 0.001; WBV + RE: 124 ± 2/72 ± 6 mmHg; RE: 126 ± 2/71 ± 6 mmHg; CON: 128 ± 2/73 ± 6 mmHg). EPOC was significantly (p < 0.001) higher at 15 minutes postexercise for WBV + RE as compared with RE. CONCLUSION: Compared with RE alone, a single bout of WBV + RE resulted in a greater postexercise hypotension response and higher EPOC.

Effects of Standing and Light-Intensity Activity on Ambulatory Blood Pressure.

PURPOSE: This study aimed to compare ambulatory blood pressure (ABP) response to accumulated standing (STAND), cycling (CYCLE), and walking (WALK) to a sitting-only (SIT) day in adults. METHODS: Nine overweight or obese (body mass index, 28.7 ± 2.7 kg · m(-2)) adults (30 ± 15 yr) participated in this randomized crossover full-factorial study. Four conditions (WALK, STAND, CYCLE, and SIT) were randomly performed 1 wk apart. WALK, STAND, and CYCLE conditions consisted of progressively increasing activity time to accumulate 2.5 h during an 8-h simulated workday. WALK (1.0 mph) and STAND (0.0 mph) were completed on a treadmill placed underneath a standing-height desk. During CYCLE, participants pedaled on a Monark cycle ergometer at a cadence and energy expenditure equivalent to WALK. Participants remained seated during the SIT condition. Participants wore an ABP cuff from 0800 h until 2200 h on all conditions. Linear mixed models were used to test condition differences in systolic (SBP) and diastolic (DBP) blood pressure. Chi-square was used to detect frequency difference of BP load. RESULTS: There was a whole-day (during and after work hours) SBP and DBP treatment effect (P < 0.01). Systolic blood pressure during STAND (132 ± 17 mm Hg), WALK (133 ± 17 mm Hg), and CYCLE (130 ± 16 mm Hg) were lower compared with that during SIT (137 ± 17 mm Hg) (all P < 0.01). CYCLE was lower than STAND (P = 0.04) and WALK (P < 0.01). For DBP, only CYCLE (69 ± 12 mm Hg) was lower than SIT (71 ± 13 mm Hg; P < 0.01). Compared with SIT, WALK, STAND, and CYCLE reduced SBP load by 4%, 4%, and 13%, respectively (all P < 0.01). CONCLUSIONS: Compared with sitting, accumulating 2.5 h of light-intensity physical activity or standing during an 8-h workday may reduce ABP during and after work hours.

Walking Workstation Use Reduces Ambulatory Blood Pressure in Adults With Prehypertension.

BACKGROUND: The acute effect of low-intensity walking on blood pressure (BP) is unclear. PURPOSE: To determine if the acute use of a walking workstation reduces ambulatory blood pressure (ABP) in prehypertensive men and women. METHODS: Ten prehypertensive adults participated in a randomized, cross-over study that included a control workday and a walking workstation workday. ABP was measured for 7 hour during the workday and for 6 hour after work. RESULTS: Both systolic BP (SBP) (134 ± 14 vs. 137 ± 16 mmHg; P = .027) and diastolic BP (DBP) (79 ± 10 vs. 82 ± 12 mmHg; P = .001) were lower on the walking workstation day. Postwork hours (4:00 PM-10:00 PM), SBP (129 ± 13 vs. 133 ± 14 mmHg; P = .008), and DBP (74 ± 11 vs. 78 ± 13 mmHg; P = .001) were also lower on the walking workstation day. DBP load was significantly lower during the walking workstation day, with only 14% of the readings above 90 mmHg compared with 22% of the control day readings (P = .037). CONCLUSION: Accumulation of very-light-intensity physical activity (~2 METs) over the course of a single work day using a walking workstation may reduce BP burden in prehypertensive individuals.