Anthony C. Hackney

University of North Carolina at Chapel Hill | UNC · Department of Exercise and Sport Science

Background/Objective Cellular immune markers of inflammation such as neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR) and systemic immune inflammation index (SII) are frequently used in patient care. The adoption of these markers to elite sports, e.g. soccer could be beneficial when monitoring training and aiming to maximize...

Objectives We investigated the timing of resistance training (RT) during Ramadan fasting (RF) on muscle strength, hormonal adaptations, and sleep quality. Methods Forty healthy and physically active male Muslims (age = 25.7 ± 5.6 years, body mass = 85.1 ± 17.5 kg, height = 175 ± 9 cm, BMI = 28.3 ± 5.7 kg/m²) were enrolled in this study and 37 comp...

Objective To determine the association between survey-based self-reported problematic low energy availability indicators (LEA-I) and race performance and intra-event medical encounters during the Boston Marathon. Methods 1030 runners who were registered for the 2022 Boston Marathon completed an electronic survey (1–4 weeks pre-race) assessing LEA-...

Background : Female-specific science, medicine, and innovation have grown steadily since the turn of the decade as the focus on female sport continues to advance. While this growth is welcome, and despite the best of intentions, it is not always coupled with valuable application. Purpose : This commentary discusses barriers faced when developing an...

Background Strength training (ST) primarily enhances physical fitness (e.g., muscle strength, power, speed) and bone density in female soccer players. Less information is available on the injury preventive effects of ST in female athletes. Accordingly, this study aimed to investigate the effects of a 12-week in-season ST on measures of physical fit...

Introduction To evaluate the effects of oral contraceptive (OC) and hormonal intrauterine device (H-IUD) use, compared to an eumenorrheic (EUM) cycle, on maximal strength and power between hormone phases. Methods One repetition max (1RM) leg press and bench press, peak force (PF) from knee extension and upright row isometric dynamometry, and power...

Introduction Resting energy expenditure (REE) may fluctuate during the menstrual cycle (MC), due to the physiological effects of estradiol (E2) and progesterone (P4). This study examined changes in REE and metabolic hormones (leptin, ghrelin, thyroid hormones), and dietary intake in two hormonally distinct groups, naturally menstruating women (NoOC...

The intent of this chapter is to provide a basic overview and explanation of the neuroendocrine system responses to an exercise session in healthy adults. Specifically, the physiologic mechanisms for inducing the hormonal responses of this system and the scope of such responses are addressed. Additionally, factors that augment or attenuate exercise...

Low energy availability, particularly when problematic (i.e., prolonged and/or severe), has numerous negative consequences for health and sports performance as characterized in relative energy deficiency in sport. These consequences may be driven by disturbances in endocrine function, although scientific evidence clearly linking endocrine dysfuncti...

This study investigated the impact of intensive endurance exercise on circulating androgenic steroid hormones in women. Fifteen normally menstruating athletic women participated. They completed intensive endurance exercise (treadmill running) until volitional fatigue in their follicular phase, with blood samples collected at pre-exercise, volitiona...

Background The pre-season preparatory period is considered key for optimizing the physical fitness levels needed to withstand congested match periods and preventing injuries during the regular soccer season. This study contrasted the effects s of neuromuscular training (NMT) versus an endurance-dominated training (ET) program conducted during the p...

Aims To evaluate the effects of 12-week chlorella vulgaris (CV) combined with interval resistance training (IRT) on plasma levels of leptin, adiponectin and neuregulin-4 (Nrg-4) in obese men. Methods Obese men (n = 44, BMI of 32.1 ± 1.5 kg/m²) were randomly allocated to the following groups of 11 participants per group: Control Placebo group (CP),...

Excessive exercise can induce cell damage and impair muscle function by generating oxidative stress. Carob rich phenolic components have attracted the attention of many researchers because of their antioxidant actions. We utilized a double-blind randomized placebo-controlled design to study the putative antioxidant role of six weeks of daily polyph...

BACKGROUND: Intra-individual factors like ovarian hormone profiles and body weight variations may influence sports practice and performance in female athletes and need to be characterized. The “Answ’Her” questionnaire was designed to develop a relevant and reproducible fieldbased tool to assess self-reported ovarian hormone status (natural menstrua...

Objective The purpose of this study was to examine the effects of 10 weeks of high-intensity interval training (HIIT) and HIIT combined with circuit resistance training (HCRT) on selected measures of physical fitness, the expression of miR-9, -15a, -34a, -145, and − 155 as well as metabolic risk factors including lipid profiles and insulin resistan...

Background Previous studies reported differences in genotype frequency of the ACTN3 R577X polymorphisms (rs1815739; RR, RX and XX) in athletes and non-athletic populations. This systematic review with meta-analysis assessed ACTN3 R577X genotype frequencies in power versus endurance athletes and non-athletes. Methods Five electronic databases (PubM...

Cabre, HE, Ladan, AN, Moore, SR, Joniak, KE, Blue, MNM, Pietrosimone, BG, Hackney, AC, and Smith-Ryan, AE. Effects of hormonal contraception and the menstrual cycle on fatigability and recovery from an anaerobic exercise test. J Strength Cond Res XX(X): 000–000, 2024—This study sought to evaluate the effects of oral contraceptive (OC) and hormonal...

Background Intermittent exercise programs characterized through intensive exercise bouts alternated with passive or active recovery (i.e., interval training), have been proven to enhance measures of cardiorespiratory fitness. However, it is unresolved which recovery type (active or passive) applied during interval training results in larger perform...

BACKGROUND: Energy availability (EA) and relative energy deficiency in sport (RED-S) are understudied in East African endurance athletes, both females (F) and males (M). This study assessed the metabolic hormonal profiles of such athletes relative to their EA status. METHODS: Forty athletes (F=16, M=24) had their EA status, training, maximal oxygen...

Introduction : The present scientific consensus is that the menstrual cycle (MC) and hormonal contraceptive (HC) cycle only influence performance trivially. Nevertheless, athletes perceive changes in performance that they associate with different phases of their hormonal cycle. Methods : A total of 959 female athletes completed a questionnaire, of...

Throughout their lifespans, women undergo unique endocrinological changes relative to their reproductive hormones. The influence of how the female sex steroid hormones have nonreproductive actions is a trending topic of great interest in the exercise–sports sciences, especially among women of reproductive age. Herein, we present several key points...

Fatty acid translocase (FAT/CD36) is a transmembrane glycoprotein belonging to the scavenger class B receptor family and is encoded by the cluster of differentiation 36 (CD36) gene. This receptor has a high affinity for fatty acids and is involved in lipid metabolism. An abundance of FAT/CD36 during exercise occurs in mitochondria and solitary musc...

Background Both strength and endurance training are included in global exercise recommendations and are the main components of training programs for competitive sports. While an abundance of research has been published regarding concurrent strength and endurance training, only a small portion of this research has been conducted in females or has ad...

The idiom ‘more high-quality research is needed’ has become the slogan for sport and exercise physiology-based research in female athletes. However, in most instances, it is challenging to address this gap of high-quality research in elite female athletes at a single study site due to challenges in recruiting enough participants with numerous menst...

Purpose Less physical activity has been associated with systemic biomarkers of cartilage breakdown following anterior cruciate ligament reconstruction (ACLR). Yet, previous research lacks analysis of deleterious cartilage compositional changes and objective physical activity following ACLR. The purpose of this study was to determine the association...

Sufficient high-quality studies in sport science using women as participants are lacking, meaning that our knowledge and understanding of female athletes in relation to their ovarian hormone profiles is limited. Consortia can be used to pool talent, expertise and data, thus accelerating our learning on a given topic and reducing research waste thro...

The 2023 International Olympic Committee (IOC) consensus statement on Relative Energy Deficiency in Sport (REDs) notes that exposure to low energy availability (LEA) exists on a continuum between adaptable and problematic LEA, with a range of potential effects on both health and performance. However, there is variability in the outcomes of LEA expo...

Relative Energy Deficiency in Sport (REDs) was first introduced in 2014 by the International Olympic Committee’s expert writing panel, identifying a syndrome of deleterious health and performance outcomes experienced by female and male athletes exposed to low energy availability (LEA; inadequate energy intake in relation to exercise energy expendit...

In the past decade, the study of relationships among nutrition, exercise and the effects on health and athletic performance, has substantially increased. The 2014 introduction of Relative Energy Deficiency in Sport (REDs) prompted sports scientists and clinicians to investigate these relationships in more populations and with more outcomes than had...

Evidence suggests that higher testosterone levels may provide an athletic advantage. Therefore, it is of practical interest to examine the association between testosterone levels and power- and strength-related traits in young professional track and field athletes, and to consider the factors that determine testosterone levels. The study involved 6...

Creatine supplementation improves anaerobic performance and recovery; however, to date, these outcomes have not been well explored in females. This study evaluated the effect of creatine monohydrate loading on exercise recovery, measured by heart rate variability (HRV) and repeated sprint performance, in women across the menstrual cycle. In this ra...

Background Well programmed strength and conditioning training is an indispensable part of the long-term training process for athletes in individual and team sports to improve performance and prevent injuries. Yet, there is a limited number of studies available that examine the effects of resistance training (RT) on muscular fitness and physiologica...

This chapter focuses on explaining the interaction between the hypothalamic–pituitary–ovarian axis, menstrual and oral contraceptive cycles with exercise. The intent herein is to give the basic physiology and endocrinology framework that allows the reader to understand the dynamic hormonal changes that occur within women as related to their reprodu...

Purpose: During Ramadan month, Muslims often continue training to maintain their muscle performance. However, trainers should stress the importance of the time of day chosen for practicing resistance training (RT) during Ramadan fasting to avoid health and performance alteration. Thus, this study aimed to investigate the effects of the timing of R...

Background: The rating of perceived exertion (RPE) is a readily available and practical tool widely used in exercise science to monitor exercise load, but a rigorous review of the effect of menstrual cycle (MC) phases on RPE within continuous aerobic exercise has not yet been completed. Objective: Therefore, the current study investigated the effec...

Low energy availability (LEA) occurs inadvertently and purposefully in many athletes across numerous sports; and well planned, supervised periods with moderate LEA can improve body composition and power to weight ratio possibly enhancing performance in some sports. LEA however has the potential to have negative effects on a multitude of physiologic...

Background: In non-athletic populations micronutrient consumption is associated with premenstrual syndrome (PMS). PMS can be a debilitating condition for female athletes as it may affect their performance and training. This study investigated potential differences in select micronutrients' intake in female athletes with or without PMS. Methods:...

This study examined the effects of creatine (Cr) loading on body mass (BM) and fluid markers of total body water (TBW), extra-cellular fluid (ECF), and intra-cellular fluid (ICF) across the menstrual cycle (MC). Thirty moderately active females, either naturally-menstruating (NM) or using hormonal contraceptives (HC), were randomized to Cr (Cr; 4 ×...

The aim of this study was to investigate the effects of 12 weeks of high-intensity training with astaxanthin supplementation on adipokine levels, insulin resistance and lipid profiles in males with obesity. Sixty-eight males with obesity were randomly stratified into four groups of seventeen subjects each: control group (CG), supplement group (SG),...

Research should equitably reflect responses in men and women. Including women in research, however, necessitates an understanding of the ovarian hormones and menstrual phase variations in both cellular and systems physiology. This review outlines recent advances in the multiplicity of ovarian hormone molecular signaling that elucidates the mechanis...

Purpose: Most women during their lifetime experience a combination of premenstrual syndrome (PMS) symptoms (eg, menstrual cramps) before and often to the end of menstruation. However, the impact of these symptoms on sport routines (eg, performance, training absence) during phases around menstruation is still unclear. Therefore, we investigated the...

We examined whether endurance training for a standard marathon (42.2 km) had a greater influence on male libido than more generalized endurance exercise training. We surveyed adult men (>1000) who regularly engaged in endurance running to evaluate exercise training histories-patterns and libido characteristics. Our participants were primarily recru...

Abstract This study aimed to examine the effects of two high-intensity interval training programs (HIIT) on maximal aerobic velocity (MAV), hematological variations and muscle damage markers in young healthy adults. Twenty-nine male physical education students, aged 20.3 ± 3.3 years, volunteered to participate in this study, and were randomly assig...

Problem: If athletes develop low energy availability (LEA), it can lead to a Relative Energy Deficiency in Sport (RED-S) syndrome which has severe health consequences if not treated. Methodology: A narrative review of the most recent and pertinent literature on the topic, with special emphasis on women. Results: In assessing the current litera...

Objective To determine the effects of different intensities of interval resistance training (IRT) protocols on the levels of select myokines (decorin, follistatin, myostatin, activin A, transforming growth factor beta-1 [TGF-β1]), and cardiometabolic and anthropometric measures in males with obesity. Methods Forty-four obese males (age: 27.5 ± 9.4...

Background Ageing is accompanied by decreases in physical capacity and physiological regulatory mechanisms including altered hormonal regulation compared with age-matched sedentary people. The potential benefits of exercise in restoring such altered hormone production and secretion compared to age-matched physically inactive individuals who are age...

The energy costs of athletic training can be substantial, and deficits arising from costs unmet by adequate energy intake, leading to a state of low energy availability, may adversely impact athlete health and performance. Life history theory is a branch of evolutionary theory that recognizes that the way the body uses energy-and responds to low en...

This pilot study assessed the feasibility and combined effect of aerobic exercise (AE) and mindfulness meditation (MM), compared with MM alone and a control (CON) condition, on stress, anxiety, and depression in high-stress college-based young adults. Thirty-two participants (84.4% F, 20.5 ± 2.7 years, 23.9 ± 5.0 kg/m2) were randomized to a four-we...

The authors present opinions based on their applied experiences of working with female athletes in combination with the existing evidence-based literature. Most of the existing menstrual cycle research focuses on a few steady-state time points within the pre-defined menstrual cycle phases, yet this disregards the day-to-day hormonal changes that wo...

Purpose: This study investigated the psychophysiological responses during self-selected exercise intensity over the course of the menstrual cycle (MC). Methods: Seventeen healthy women with regular MCs completed three randomized treadmill bouts of 30 min of self-selected exercise intensity during menstruation, mid-follicular, and late luteal phases...

Purpose: To investigate the awareness and knowledge regarding various general sports endocrinology concepts and specific practices related to sport performance and health in the Russian track and field athletes. Methods: Professional Russian track-field athletes (n = 50, age = 23.1 y) were divided into 3 groups according to their level of sports p...

Previous studies have not considered the potential influence of maturity status on the relationship between mental imagery and change of direction (CoD) speed in youth soccer. Accordingly, this cross-sectional study examined the association between mental imagery and CoD performance in young elite soccer players of different maturity status. Forty...

Purpose: To determine the relationship between gastrointestinal hormones (leptin, glucagon-like peptide-1), ghrelin, cholecystokinin, peptide YY, morphological characteristics, and physical performances in elite soccer players. Methods: Q2 Twenty-two elite male soccer players (age = 23.1 [2.7] y, height = 177.0 [0.1] cm, weight = 70.2 [2.9] kg,...

Background Home-based training increases accessibility to exercise and mitigates the side effects of hormone therapy for prostate cancer (PC). However, it is unknown if men with more advanced disease are willing to partake in such interventions. Purpose To determine the feasibility of a home-based exercise intervention in men with metastatic castr...

Background: The standard method to treat physically active patients with anterior cruciate ligament (ACL) rupture is ligament reconstruction surgery. The rehabilitation training program is very important to improve functional performance in recreational athletes following ACL reconstruction. Objectives: The aims of this study were to compare the ef...

Purpose: To examine the effects of fatiguing power-loading on neuromuscular properties, force production, and metabolic capacities during four phases of the menstrual cycle (MC); menstruation (M), mid-follicular (mid FOL), ovulation (OV), and mid-luteal (mid LUT). Methods: Sixteen eumenorrheic women performed sessions of maximal explosive leg pr...

Background: Change-of-direction (CoD) is a necessary physical ability of a field sport and may vary in youth players according to their maturation status. Objectives: The aim of this study is: to compare the effectiveness of a 6-week CoD training intervention on dynamic balance (CS-YBT), horizontal jump (5JT), speed (10 and 30-m linear sprint times...

Objectives: To evaluate body composition, fat distribution, and metabolism at rest and during exercise in premenopausal, perimenopausal, and postmenopausal women. Methods: This cross-sectional study in 72 women ages 35 to 60 years evaluated body composition via a fourcompartment model, fat distribution using dual-energy x-ray absorptiometry-deri...

Beta-alanine, caffeine, and nitrate are dietary supplements generally recognized by the sport and exercise science community as evidence-based ergogenic performance aids. Evidence supporting the efficacy of these supplements, however, is greatly skewed due to research being conducted primarily in men. The physiological differences between men and w...

Background Osteoporosis causes bone fragility, increasing the risk of fractures. Evidence suggests a strong correlation between obesity and fracture risk. Physical training is known to enhance bone resistance and protect from fracture; however, its osteogenic effect in the presence of obesity remains unknown. Objective We sought to evaluate the in...

Context: Individuals who undergo anterior cruciate ligament reconstruction (ACLR) are at higher risk of posttraumatic osteoarthritis (PTOA). Altered joint tissue loading caused by aberrant gait biomechanics leads to deleterious changes in joint health linked to PTOA onset. Knee braces have been used to modify joint tissue loading in individuals wi...