Objectives: To investigate the effects of 12-week high-intensity- (HIIT) vs. moderate-intensity-interval training (MIIT) on thyroid stimulating hormone (TSH) and thyroxine (T4) and insulin-resistance in overweight/obese adolescent girls. Methods: Twenty four adolescent girls (age 16.5±1.36 yrs) were randomly allocated into three groups: (1) HIIT (2 blocks per session of 6–8 bouts of 30 s runs at 100–110% maximal aerobic speed (MAS), with 30 s active recovery between bouts at 50% MAS; n=8), (2) MIIT (2 blocks per session of 6–8 bouts of 30 s runs at 70–80% MAS, with 30 s active recovery between bouts at 50% MAS; n=8) and (3) control group (no exercise, n=8). Each training groups engaged in three sessions per week during three months. Anthropometric parameters, aerobic capacity, homeostasis model assessment index for insulin resistance (HOMA-IR) as well as plasma TSH and T4 levels were assessed in all subjects before- and after-training. Results: Following both training programs, body mass, body mass index Z-score, waist circumference and body fat decreased, while aerobic capacity increased. However, TSH and T4 concentrations decreased only after the HIIT (−30.47%, p<0.05, ES=1.42 and −12.86%, p<0.05, ES=1.18; respectively). The HOMA-IR decreased in both training groups (−26.25%, p<0.05, ES=1.87 for MIIT and −21.72%, p<0.05, ES=2.14 for HIIT). Conclusion: Twelve weeks of HIIT was effective in reducing circulating TSH and T4 levels, unlike MIIT, in overweight/obese adolescent girls. These findings indicated that the stimulation of pituitary-thyroid function is more sensitive to training intensity than training duration. Further studies are needed to confirm this conclusion.

Background/Objectives: Despite the abundant body of evidence linking high-intensity interval training (HIIT) to cardiometabolic markers, little is known about how HIIT affects liver enzymes, particularly in obese adolescents. This study aimed to investigate the effects of HIIT on metabolic dysfunction-associated steatotic liver disease (MASLD)-related biomarkers in overweight/obese adolescent girls. Methods: Thirty-three overweight/obese adolescent girls (age, 17.0 ± 1.15 yr.; body mass index, 33.3 ± 4.77 kg/m²) were randomly assigned to HIIT (n = 17) or control (n = 16) groups. The HIIT group participated in a nine-week HIIT program (three times weekly) without caloric restriction. Maximal aerobic speed, body composition indexes, blood pressure, MASLD-related biomarkers [liver enzymes (alanine aminotransferase (ALT) and aspartate aminotransferase (AST)), plasma lipids, uric acid, platelet count, and homeostasis model assessment index for insulin-resistance (HOMA-IR)] were examined at baseline and after the intervention. Results: Significant “time × group” interactions were found for body composition indexes, systolic blood pressure, maximal aerobic speed, liver enzymes ALT and AST, plasma lipids, glucose, and HOMA-IR. The HIIT program resulted in an increase in maximal aerobic speed (p = 0.035) and a decrease in body composition and plasma lipids (p < 0.01), systolic blood pressure (p = 0.011), ALT (p = 0.013), AST (p = 0.012), and HOMA-IR (p = 0.01), but no significant changes in uric acid and platelet count. None of these markers changed in the control group. Conclusions: HIIT resulted in an improvement in MASLD-related biomarkers. HIIT could be an effective exercise therapy to prevent and reverse MASLD in adolescents with obesity.

This study aimed to investigate the impact of a 10-week moderate intermittent walking training (MIWT) program on thyroid hormone levels and key cardiometabolic markers in obese postmenopausal women. Thirty-six obese postmenopausal women (body mass index ≥ 30 kg.m^-2, aged 50-60 years) were randomized to either the MIWT group (n = 18) or the control group (CG; n = 18). Participants performed the MIWT program for four sessions per week (five repetitions of the 6-min walking test [6MWT] at 60-80% of the distance covered in the 6-min walking test [6MWD], interspersed by 6 min of active recovery between repetitions). Body composition, thyroid hormones (thyroid stimulating hormone [TSH] and thyroxine-free [FT4]), lipid profile (triglycerides [TRG], total cholesterol [TC], high-density lipoprotein cholesterol [HDL-C] and low-density lipoprotein cholesterol [LDL-C]), blood pressure and aerobic fitness (6MWT) were determined before and after the MIWT. The MIWT resulted in significant reductions in body composition (p < 0.05), TSH (-5.29%, p = 0.019, d = 0.16), FT4 (-1.84%, p = 0.032, d = 0.28), TRG (-7.29%, p = 0.003, d = 0.27), TC (-4.98%, p = 0.003, d = 0.31), LDL-C (-10.08%, p = 0.003, d = 0.51) and SBP (-2.57%, p = 0.035, d = 0.66), and significant increases in HDL-C (13.36%, p = 0.020, d = 0.52) and 6MWD (2.81%, p = 0.031, d = 0.51). A 10-week MIWT program modestly improved thyroid hormones, cardiometabolic risk and functional capacity in obese postmenopausal women without adverse effects. MIWT is an accessible and low-impact intervention suitable for integration into routine clinical practice to prevent and manage thyroid-related and cardiometabolic disorders in this high-risk population.

Ghrelin, a gastric-derived peptide, regulates appetite, food intake, and energy homeostasis. Body weight plays a crucial role in modulating circulating ghrelin levels. Since exercise training is one of the most valuable tools for controlling body weight, it is relevant to consider whether exercise can influence total ghrelin secretion. This study aims to perform a systematic review of the effect of acute/chronic exercise on plasma ghrelin levels. An extensive literature search was carried out on various databases, including PubMed, ScienceDirect, and Google Scholar. The search was conducted using English keywords such as acute-exercise, transient-exercise, exercise, chronic-exercise, training, physical-activity, physical-training, exercise training, and total-ghrelin, ghrelin, appetite-related-peptides, gastrointestinal-peptides, gastrointestinal-hormones, and appetite-regulating-hormone. Initially, 2104 studies were identified. After evaluating study quality, data from 61 relevant studies were extracted for inclusion in this review. Most studies indicated that short-term acute aerobic exercise did not affect total ghrelin levels regardless of exercise intensity, characteristics, or growth hormone (GH) secretion. However, long and very-long aerobic/chronic exercise increased total ghrelin levels, mainly in overweight/obese individuals. Acute/chronic exercise may differentially influence total ghrelin secretion. Short-term acute aerobic exercise induces stable plasma ghrelin concentrations, independent of GH secretion. Long-term aerobic training increased its levels mainly in overweight/obese individuals through body composition and oxidative stress reduction. Additionally, total ghrelin secretion is more sensitive to exercise/training duration than exercise/training intensity.

Postmenopausal obesity is an important public health concern, accompanied by increased systemic inflammation that heightens the risk of liver disease. Exercise improved both inflammatory and hepatic function. Moderate‐intensity intermittent‐walking training (MIWT) is considered a feasible approach for postmenopausal women with obesity. This study aimed to investigate whether MIWT could reduce the risk by modulating hepatic enzymes and selected inflammatory markers. Thirty‐six sedentary postmenopausal women with obesity (mean age 55.7 ± 3.5 years; mean weight: 86.9 ± 12.2 kg; mean BMI: 34.0 ± 5.0 kg/m ² ) were randomly assigned to a training group (TG, n = 18) or a control group (CG, n = 18). The TG completed a 10‐week MIWT protocol (4 sessions/week, ∼85 min/session), involving repeated walking intervals at 60%–80% of the 6MWT distance with active recovery. As a secondary objective, changes in body composition and aerobic capacity were also assessed. Significant improvements were observed in the TG group in liver enzymes alanine‐transaminase (ALT), ( p = 0.002, d = 0.29), aspartate‐transaminase (AST) ( p = 0.013, d = 0.29), gamma‐glutamyl‐transferase (GGT) ( p = 0.036, d = 0.25), total bilirubin ( p = 0.009, d = 0.13), and C‐reactive‐protein (CRP) ( p = 0.007, d = 0.49). Additionally, significant reductions were found in body mass ( p < 0.001), BMI ( p < 0.001), body fat ( p = 0.001), and waist circumference ( p < 0.001), along with increased aerobic capacity ( p = 0.031). These findings indicate that MIWT is a feasible and effective intervention for inducing favorable changes in liver‐related biochemical markers and systemic inflammation, with additional benefits for body composition and aerobic fitness in postmenopausal women with obesity.

The study investigated the effects of high-intensity interval training (HIIT) on cardiorespiratory fitness, hormonal, and psychological markers in adolescents. Twenty-eight healthy male adolescents were randomized to a HIIT group or a non-training control group. HIIT comprises three sessions per week for 10 weeks, alternating 30 s runs at high-intensity and low-intensity. VO_2max was estimated using the incremental running test. Plasma testosterone and cortisol were assessed by ELISA methods. Depression, anxiety, and stress scores were determined using the Depression Anxiety Stress Scales-21. Data were analyzed using two-way ANOVA with repeated measures. Significant “group × time” interactions were detected for VO_2max, testosterone, cortisol, testosterone-to-cortisol ratio, and stress score, but not for anxiety and depression scores. HIIT resulted in increased VO_2max (p < 0.001, d = 1.04), testosterone (p = 0.005, d = 0.52), and testosterone-to-cortisol ratio (p = 0.008, d = 1.05), and decreased cortisol (p = 0.036, d = 1.09) and stress score (p = 0.020, d = 0.98). Ten-week HIIT resulted in an improvement in physical fitness, steroid hormonal balance, and self-reported stress symptoms, but no changes in depressive and anxiety symptoms in comparison to the control group. The findings should be interpreted with caution due to limitations, including the small sample size and the lack of assessment of sex-related differences. Further research is required to elucidate the topic.