Tunde K. Szivak

Kraemer, WJ, Volek, JS, Stephenson, MD, Szivak, TK, Saenz, C, Buga, A, Lee, EC, Ratamess, NA, Post, EM, Caldwell, LK, Hagen, JA, and Maresh, CM. Endocrine, skeletal, and circadian biomarker profiles across operational phases in elite special forces operators. J Strength Cond Res XX(X): 000–000, 2026—This investigation examined multisystem biomarker responses across distinct operational phases in elite Special Forces operators and evaluated whether integrated patterns, including principal component analysis (PCA), could reveal coherent signatures of stress and recovery. Fifty-six male operators (28–42 years, 175–187 cm, 77–95 kg) participated in a longitudinal study. Resting venous blood samples were obtained at 3 visits aligned with recovery/reset (visit 1), peak training stress (visit 2), and reintegration (visit 3). Serum analytes included 25-hydroxy vitamin D, triiodothyronine (T3), β-C-terminal telopeptide (CTX), melatonin, C-reactive protein (CRP), R-β-hydroxybutyrate (R-BHB), and plasma samples for ghrelin, neuropeptide Y (NPY), and vascular endothelial growth factor (VEGF). All biomarkers were analyzed in duplicate using ELISA. Repeated-measures analysis of variance with Bonferroni correction ( p ≤ 0.05) and exploratory PCA were performed. Vitamin D and T3 declined significantly from visit 1 to visit 2 (−16% and −30%; p < 0.001) and remained suppressed at visit 3. CTX decreased markedly at visit 2 (−87%; p < 0.001) but recovered by visit 3. Ghrelin increased at visit 2 (+16%; p = 0.002), whereas NPY increased only at visit 3. Melatonin doubled at visit 2 (+105%; p < 0.001) and remained elevated. R-BHB, VEGF, and CRP did not change significantly. Exploratory PCA identified 3 components representing hormonal-circadian regulation, metabolic-inflammatory strain, and neuroendocrine appetite regulation. A phase-based, multisystem biomarker panel, supported by PCA-derived physiological axes, identified coherent signatures of operational stress and recovery. These findings support the use of integrated biomarker monitoring to characterize system-level stress responses and inform phase-specific recovery and readiness strategies in elite tactical populations.

Background/Objectives: This scoping review critically evaluated existing literature and summarized the impact of occupational, physiological, and psychological stressors on adrenal and neuroendocrine responses, body composition, and physical performance amongst women in tactical occupations. Methods: Boolean searches identified potentially qualifying reports involving: (1) adult women (≥19 y) currently employed or completing their training for a tactical profession; (2) ≥1 marker of “stress”; and (3) ≥1 adrenal, neuroendocrine, body composition, or fitness/performance outcome. Quantitative data (e.g., sample characteristics, outcomes of interest) were extracted and summarized. The completeness of reporting for each study was documented using existing checklists and quantified as: low (k) of moderate reporting quality (~64%) were included in the final sample (3693 women); 11 studies (28%) focused on women exclusively, and 16 studies identified sex differences in ≥1 outcome. Most studies involved military trainee populations (80%, k = 32). Occupation-related stress tended to negatively impact adrenal, neuroendocrine, body composition, and performance outcomes. Conclusions: This review highlights progress in assessing occupational performance in female tactical personnel exposed to diverse stressors; however, our understanding remains incomplete due to methodological and conceptual limitations in the literature. Holistic research strategies are needed to capture the complexity of performance readiness in women, integrating how stress affects key tactical performance aspects such as muscle physiology, reproductive health, and energy and nutrient balance in realistic operational contexts. Integrating such data is vital for informing policy, improving readiness, and enhancing the health and career longevity of female tactical personnel.

Szivak, TK, Thomas, MM, Pietrzak, RH, Nguyen, DR, Ryan, DM, and Mazure, CM. Obesity Risk Among West Point Graduates Later in Life. J Strength Cond Res 37(6): 1284–1291, 2023—The purpose of this investigation was to evaluate sex differences in health and fitness outcomes among United States Military Academy (USMA) graduates (class years 1980–2011). Subjects (n = 701 men, 641 women, age: 45.7 ± 9.3 years) were surveyed as a part of a larger investigation on risk and resiliency factors among USMA graduates. Physical activity was assessed using the International Physical Activity Questionnaire (IPAQ) short form and calculation of weekly metabolic equivalents (METs). Overweight and obesity status were assessed by body mass index (BMI). Significance for the study was set at p ≤ 0.05. Obesity rates for men (30.1%) were significantly higher than for women (16.6%). Men reported significantly higher (p = 0.01) vigorous METs·wk⁻¹ (1,214.6 ± 1,171.6) than women (1,046.8 ± 1,133.2) despite significantly higher (p = 0.00) BMI values (28.75 ± 4.53 kg·m⁻²) than women (25.90 ± 5.48 kg·m⁻²). Women were 89% more likely to have ever been on a diet and reported higher (15.2%) Army Body Composition Program enrollment rates than men (6.3%). Obesity rates among men reflect trends seen in the broader military, Veteran, and U.S. adult populations, whereas obesity rates among women were lower. Men may be at a greater risk for obesity later in life despite higher self-reported physical activity; however, lean body mass and self-report bias should be considered. Because lifetime obesity may be influenced by factors other than physical activity, health initiatives should use a comprehensive approach early in the career of military officers.

Nichols, IA and Szivak, TK. Effects of different hand widths on plyometric push-up performance. J Strength Cond Res 35(2S): S80–S83, 2021—The purpose of this study was to investigate the effects of hand width placement during the performance of plyometric push-ups. Ten male subjects (age: 24.14 ± 2.79 years, height: 178.14 ± 5.21 cm, and body mass: 91.55 ± 6.04 kg) performed 2 plyometric push-ups at 120, 150, and 170% of the subject's biacromial width (6 total push-ups) in a randomized order. Height (H), peak force (pF), peak power (pP), and rate of power development data were collected using a force plate. One-way repeated-measures analysis of variance showed no significant differences in performance measures across all hand widths. A secondary analysis using a mixed-effects linear regression model was performed due to the small sample size. Regression analysis showed a significant difference in pF (p < 0.05) between 120 and 170% hand widths. Study results suggest that although upper-body (UB) power output seems to be similar across varying hand widths, UB force development (pF) may be significantly affected by hand width during the plyometric push-up. Study results suggest that hand-width placement may impact plyometric performance measures and should be considered if the plyometric push-up is used to assess an individual's UB power. To the best of authors' knowledge, this is the first study to investigate the effects of varying hand widths on plyometric push-up performance.