Pilot study: an acute bout of high intensity interval exercise increases 12.5 h GH secretion

Exercise Intervention for Alzheimer's Disease: Unraveling Neurobiological Mechanisms and Assessing Effects

Alzheimer's disease (AD) is a progressive neurodegenerative disease and a major cause of age-related dementia, characterized by cognitive dysfunction and memory impairment. The underlying causes include the accumulation of beta-amyloid protein (Aβ) in the brain, abnormal phosphorylation, and aggregation of tau protein within nerve cells, as well as neuronal damage and death. Currently, there is no cure for AD with drug therapy. Non-pharmacological interventions such as exercise have been widely used to treat AD, but the specific molecular and biological mechanisms are not well understood. In this narrative review, we integrate the biology of AD and summarize the knowledge of the molecular, neural, and physiological mechanisms underlying exercise-induced improvements in AD progression. We discuss various exercise interventions used in AD and show that exercise directly or indirectly affects the brain by regulating crosstalk mechanisms between peripheral organs and the brain, including "bone-brain crosstalk", "muscle-brain crosstalk", and "gut-brain crosstalk". We also summarize the potential role of artificial intelligence and neuroimaging technologies in exercise interventions for AD. We emphasize that moderate-intensity, regular, long-term exercise may improve the progression of Alzheimer's disease through various molecular and biological pathways, with multimodal exercise providing greater benefits. Through in-depth exploration of the molecular and biological mechanisms and effects of exercise interventions in improving AD progression, this review aims to contribute to the existing knowledge base and provide insights into new therapeutic strategies for managing AD.

Extraordinary claims in the literature on high-intensity interval training (HIIT): III. Critical analysis of four foundational arguments from an interdisciplinary lens

Kinesiology aspires to be an integrated, interdisciplinary field that studies human movement from multiple perspectives. However, the main societal deliverables of the field, namely exercise prescriptions and physical activity recommendations, still reflect fragmentation, placing more emphasis on physiological outcomes than on behavioral and other considerations. Recently, researchers have called for the introduction of High-Intensity Interval Training (HIIT) to the domain of public health, based on the argument that HIIT can maximize fitness and health benefits for a fraction of the time recommended by the prevailing model of physical activity in public-health guidelines. Here, we show that an unintended side-effect of arguments underpinning the implementation of HIIT in the domain of public health might have been the exacerbation of segmentation. To highlight the value of interdisciplinarity, four foundational claims in support of HIIT are critiqued by tapping into cognate literatures: (1) the primary reason people do not exercise is lack of time, (2) HIIT is relevant to public health, (3) HIIT is being proposed as merely another option, so there is no basis for controversy, and (4) HIIT is safe and well tolerated. These claims are contradicted by credible lines of evidence. To improve the accuracy and effectiveness of its public claims, kinesiology should remain committed to the ideals of integration and interdisciplinarity.

Endocrine responses of the stress system to different types of exercise

Physical activity is an important part of human lifestyle although a large percentage of the population remains sedentary. Exercise represents a stress paradigm in which many regulatory endocrine systems are involved to achieve homeostasis. These endocrine adaptive responses may be either beneficial or harmful in case they exceed a certain threshold. The aim of this review is to examine the adaptive endocrine responses of hypothalamic-pituitary-adrenal axis (HPA), catecholamines, cytokines, growth hormone (GH) and prolactin (PRL) to a single bout or regular exercise of three distinct types of exercise, namely endurance, high-intensity interval (HIIE) and resistance exercise. In summary, a single bout of endurance exercise induces cortisol increase, while regular endurance exercise-induced activation of the HPA axis results to relatively increased basal cortisolemia; single bout or regular exercise induce similar GH peak responses; regular HIIE training lowers basal cortisol concentrations, while catecholamine response is reduced in regular HIIE compared with a single bout of HIIE. HPA axis response to resistance exercise depends on the intensity and volume of the exercise. A single bout of resistance exercise is characterized by mild HPA axis stimulation while regular resistance training in elderly results in attenuated inflammatory response and decreased resting cytokine concentrations. In conclusion, it is important to consider which type of exercise and what threshold is suitable for different target groups of exercising people. This approach intends to suggest types of exercise appropriate for different target groups in health and disease and subsequently to introduce them as medical prescription models.

Home-Based High-Intensity Interval Exercise Improves the Postprandial Glucose Response in Young Adults with Postprandial Hyperglycemia

Postprandial hyperglycemia can be corrected by exercise; however, the effect of home-based high-intensity interval exercise (HIIE), a new time-efficient exercise, on glycemic control is unclear. This study aimed to investigate the effect of home-based HIIE on postprandial hyperglycemia. Twelve young adult males (mean age: 24.3 ± 2.3 y) with postprandial hyperglycemia that had not yet led to diabetes completed home-based HIIE, moderate-intensity continuous exercise (MICE), and control conditions on separate days, randomly. The intervention began 30 min after the start of a standardized meal intake, with 11 min of HIIE completed at maximal effort in the home-based HIIE condition, 30 min of running performed at 50% maximum oxygen uptake in the MICE condition, or 30 min of sitting at rest completed in the control condition. The participants sat at rest after each intervention for up to 120 min. Interstitial fluid glucose concentrations were measured using a continuous glucose monitoring system that scanned every 15 min for up to 2 h after the meal. The glucose concentrations after the meal were significantly lower in the home-based HIIE and MICE conditions than in the control condition (p < 0.001). There were no significant differences in the glucose concentrations between the home-based HIIE and MICE conditions. In conclusion, home-based HIIE was able to correct postprandial hyperglycemia.

Analysis of the correlation between the severity of neonatal hypoxic ischemic encephalopathy and multiple organ dysfunction

OBJECTIVE

To evaluate the hypoxic ischemic encephalopathy (HIE) and multiple organ dysfunction (MOD) in neonates and analyze the correlation between the two disorders.

METHODS

From January 2018 to January 2020, infants with HIE who were born in our hospital at or above 37 weeks of gestation, and those with ischemic hypoxic encephalopathy at or above 2000 grams were selected as study subjects. HIE and MOD monitoring were performed for three days. HIE severity was graded according to reported scores including amplitude integrated EEG. Multiple organ dysfunction was also assessed. The correlation between neonatal hypoxic ischemic encephalopathy and multiple organ dysfunction was analyzed.

RESULTS

Children with HIE were divided into three grades: mild, moderate and severe. There were statistically significant differences among the three groups in emergency caesarean section, Apgar 5 minutes, systemic hypothermia and neonatal mortality. Differences in MOD scores were found in three HIE stages per day from Day 1 to Day 3. Among children with mild HIE grading, the most common mildly affected organ systems are pH, electrolyte imbalance and liver system, and the least affected organs are kidney and blood systems. Among children with HIE grade of mild and severe, there was no significant difference in moderate-severe organ involvement, and the number of severely affected children was small.

CONCLUSION

With the increase of HIE severity, multi-organ involvement is aggravated. The organ involvement of HIE children with different degrees of severity is different.

Effects of Growth Hormone Receptor Ablation in Corticotropin-Releasing Hormone Cells

Corticotropin-releasing hormone (CRH) cells are the dominant neuronal population responsive to the growth hormone (GH) in the paraventricular nucleus of the hypothalamus (PVH). However, the physiological importance of GH receptor (GHR) signaling in CRH neurons is currently unknown. Thus, the main objective of the present study was to investigate the consequences of GHR ablation in CRH-expressing cells of male and female mice. GHR ablation in CRH cells did not cause significant changes in body weight, body composition, food intake, substrate oxidation, locomotor activity, glucose tolerance, insulin sensitivity, counterregulatory response to 2-deoxy-D-glucose and ghrelin-induced food intake. However, reduced energy expenditure was observed in female mice carrying GHR ablation in CRH cells. The absence of GHR in CRH cells did not affect anxiety, circadian glucocorticoid levels or restraint-stress-induced corticosterone secretion and activation of PVH neurons in both male and female mice. In summary, GHR ablation, specifically in CRH-expressing neurons, does not lead to major alterations in metabolism, hypothalamic-pituitary-adrenal axis, acute stress response or anxiety in mice. Considering the previous studies showing that central GHR signaling regulates homeostasis in situations of metabolic stress, future studies are still necessary to identify the potential physiological importance of GH action on CRH neurons.

High-intensity interval exercise test stimulates growth hormone secretion in children

BACKGROUND

exercise stimulates growth hormone (GH) secretion and may serve as a promising physiological test for the diagnosis of GH deficiency. However, exercise standardization for a feasible GH test is still lacking. The aim of the present study was to examine the GH secretion to high intensity interval exercise.

METHODS

Seventeen children (12.4 ± 2.6 years) with impaired growth rate performed high-intensity interval exercise test (HIIE) that included 10 intervals of 15 s all out pedaling against resistance determined by age, sex and weight on a cycle ergometer with 1-min active rest between each interval. Power output measurements were collected during the test. Blood samples were collected before, immediately after, 30, 45, and 60min after the beginning of the exercise test. GH response was compered to pharmacological provocation test (clonidine or glucagon).

RESULTS

HIIE led to a significant increase in GH levels (p < 0.001), with high correlation to GH response following pharmacological stimulation (r = 0.82, r = 0.80 for clonidine and glucagon respectively, p < 0.001) A significant correlation was found between mean peak power to body weight and the GH response (r = 0.50, p = 0.04). 83% of the participants who reached peak power > 10 watts/kg had normal GH secretion.

CONCLUSIONS

HIIE is a brief and individualized exercise protocol that may be used as a physiological provocation test for GH secretion. There might be a minimum of anaerobic power needed to induce adequate GH response during HIIE.

Deletion of growth hormone receptor in hypothalamic neurons affects the adaptation capacity to aerobic exercise

The hypothalamus mediates important exercise-induced metabolic adaptations, possibly via hormonal signals. Hypothalamic leptin receptor (LepR)- and steroidogenic factor 1 (SF1)-expressing neurons are directly responsive to growth hormone (GH) and deletion of GH receptor (GHR) in these cells impairs neuroendocrine responses during situations of metabolic stress. In the present study, we determined whether GHR ablation in LepR- or SF1-expressing cells modifies acute and chronic metabolic adaptations to exercise. Male mice carrying deletion of GHR in LepR- or SF1-expressing cells were submitted to 8 weeks of treadmill running training. Changes in aerobic performance and exercise-induced metabolic adaptations were determined. Mice carrying GHR deletion in LepR cells showed increased aerobic performance after 8 weeks of treadmill training, whereas GHR ablation in SF1 cells prevented improvement in running capacity. Trained mice carrying GHR ablation in SF1 cells exhibited increased fat mass and reduced cross-sectional area of the gastrocnemius muscle. In contrast, deletion of GHR in LepR cells reduced fat mass and increased gastrocnemius muscle hypertrophy, energy expenditure and voluntary locomotor activity in trained mice. Although glucose tolerance was not significantly affected by targeted deletions, glycemia before and immediately after maximum running tests was altered by GHR ablation. In conclusion, GHR signaling in hypothalamic neurons regulates the adaptation capacity to aerobic exercise in a cell-specific manner. These findings suggest that GH may represent a hormonal cue that informs specific hypothalamic neurons to produce exercise-induced acute and chronic metabolic adaptations.

Pilot study: an acute bout of high intensity interval exercise increases 12.5 h GH secretion

The purpose of this study was to test the hypothesis that high‐intensity interval exercise (HIE) significantly increases growth hormone (GH) secretion to a greater extent than moderate‐intensity continuous exercise (MOD) in young women. Five young, sedentary women (mean ± SD; age: 22.6±1.3 years; BMI: 27.4±3.1 kg/m²) were tested during the early follicular phase of their menstrual cycle on three occasions. For each visit, participants reported to the laboratory at 1700 h, exercised from 1730–1800 h, and remained in the laboratory until 0700 h the following morning. The exercise component consisted of either 30‐min of moderate‐intensity continuous cycling at 50% of measured peak power (MOD), four 30‐s “all‐out” sprints with 4.5 min of active recovery (HIE), or a time‐matched sedentary control using a randomized, cross‐over design. The overnight GH secretory profile of each trial was determined from 10‐min sampling of venous blood from 1730–0600 h, using deconvolution analysis. Deconvolution GH parameters were log transformed prior to statistical analyses. Calculated GH AUC (0–120 min) was significantly greater in HIE than CON (P = 0.04), but HIE was not different from MOD. Total GH secretory rate (ng/mL/12.5 h) was significantly greater in the HIE than the CON (P = 0.05), but MOD was not different from CON or HIE. Nocturnal GH secretion (ng/mL/7.5 h) was not different between the three trials. For these women, in this pilot study, a single bout of HIE was sufficient to increase 12.5 h pulsatile GH secretion. It remains to be determined if regular HIE may contribute to increased daily GH secretion.