Carl M. Maresh

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.

Premenstrual Syndrome (PMS) is a complex physiological and psychological condition that affects a significant number of women during their reproductive years. Although the exact etiology of PMS remains unclear, its symptoms, including mood swings, bloating, irritability, and fatigue, can significantly impair the quality of life for affected individuals. The management of PMS traditionally involves pharmacological interventions; however, emerging evidence suggests that exercise may offer a valuable non-pharmacological approach to alleviate PMS symptoms. This narrative review aims to explore the proposed etiology, prevalence, and impact PMS has on women as well as examine the literature through which exercise can positively influence PMS symptoms. While the existing literature on exercise and PMS is limited and inconclusive, several studies have reported promising results. Regular exercise has been associated with a reduction in physical and psychological symptoms of PMS including pain, fatigue, mood disturbances, and water retention. Furthermore, exercise has demonstrated its potential to enhance overall well-being and mitigate the negative effects of PMS on daily functioning. Further research is warranted to elucidate the optimal exercise prescription, duration, and intensity required to maximize the benefits and improve the understanding of exercise mechanisms on PMS symptomatology.

Cold water immersion (CWI) purportedly reduces inflammation and improves muscle recovery after exercise, yet its effectiveness in specific contexts (ultraendurance) remains unclear. Thus, our aim was to study hematological profiles, systemic inflammation, and muscle damage responses to a specific post-race CWI (vs. control) during recovery after the Ironman World Championship, a culmination of ∼100 000 athletes competing in global qualifying Ironman events each year. Twenty-nine competitors were randomized into either a CWI or control (CON) group. Physiological parameters and blood samples were taken at pre-race, after intervention (POST), and 24 (+1DAY) and 48 hours (+2DAY) following the race. Muscle damage markers (plasma myoglobin, serum creatine kinase) were elevated at POST, +1DAY, and +2DAY, while inflammatory cytokines interleukin (IL)-6, IL-8, and IL-10 and total leukocyte counts were increased only at POST. CWI had no effect on these markers. Numbers of the most abundant circulating cell type, neutrophils, were elevated at POST more so in CWI (p < 0.05, vs. CON). Despite that neutrophil counts may be a sensitive marker to detect subtle effects, CWI does not affect recovery markers 24- and 48-hours post-race (vs. CON). Overall, we determined that our short CWI protocol was not sufficient to improve recovery. Novelty: Ironman World Championship event increased circulating muscle damage markers, inflammatory markers, and hematological parameters, including circulating immune cell sub-populations that recover 24–48 hours after the race. 12-min CWI post-ultraendurance event affects the absolute numbers of neutrophils acutely, post-race (vs. CON), but does not impact recovery 24- and 48-hours post-race.

The combination of hyperthermia, dehydration, and strenuous exercise can result in severe reductions in kidney function, potentially leading to acute kidney injury (AKI). We sought to determine whether six days of heat acclimation (HA) mitigates the rise in clinical biomarkers of AKI during strenuous exercise in the heat. Twenty men completed two consecutive 2 h bouts of high-intensity exercise in either hot (n = 12, 40 °C, 40% relative humidity) or mild (n = 8, 24 °C, 21% relative humidity) environments before (PreHA) and after (PostHA) 4 days of 90–120 min of exercise per day in a hot or mild environment. Increased clinical biomarkers of AKI (CLINICAL) was defined as a serum creatinine increase ≥0.3 mg·dL⁻¹ or estimated glomerular filtration rate (eGFR) reduction >25%. Creatinine similarly increased in the hot environment PreHA (0.35 ± 0.23 mg·dL⁻¹) and PostHA (0.39 ± 0.20 mg·dL⁻¹), with greater increases than the mild environment at both time points (0.11 ± 0.07 mg·dL⁻¹, 0.08 ± 0.06 mg·dL⁻¹, p ≤ 0.001), respectively. CLINICAL occurred in the hot environment PreHA (n = 9, 75%), with fewer participants with CLINICAL PostHA (n = 7, 58%, p = 0.007), and no participants in the mild environment with CLINICAL at either time point. Percent change in plasma volume was predictive of changes in serum creatinine PostHA and percent changes in eGFR both PreHA and PostHA. HA did not mitigate reductions in eGFR nor increases in serum creatinine during high-intensity exercise in the heat, although the number of participants with CLINICAL was reduced PostHA.

Background: Surprisingly little is known about the physiological and perceptual differences of women who consume different volumes of water each day. The purposes of this investigation were to (a) analyze blood osmolality, arginine vasopressin (AVP), and aldosterone; (b) assess the responses of physiological, thirst, and hydration indices; and (c) compare the responses of individuals with high and low total water intake (TWI; HIGH and LOW, respectively) when consuming similar volumes of water each day and when their habitual total water intake was modified. Methods: In a single-blind controlled experiment, we measured the 24 h total water intake (TWI; water + beverages + food moisture) of 120 young women. Those who consumed the highest (HIGH, 3.2 ± 0.6 L·day⁻¹, mean ± SD) and the lowest (LOW, 1.6 ± 0.5 L·day⁻¹) mean habitual TWI were identified and compared. Outcome variables were measured during two ad libitum baseline days, a four-day intervention of either decreased TWI (HIGH) or increased TWI (LOW), and one ad libitum recovery day. Results: During the four-day intervention, HIGH and LOW experienced differences in thirst (p = 0.002); also, a statistically significant change of AVP occurred (main effect of TWI and day, p < 0.001), with no effect (TWI or day) on aldosterone and serum osmolality. Urine osmolality and volume distinguished HIGH from LOW (p = 0.002) when they consumed similar 24 h TWI.