High-Intensity Interval Training Attenuates Insulin Resistance Induced by Sleep Deprivation in Healthy Males

Short Sleep Duration Disrupts Glucose Metabolism: Can Exercise Turn Back the Clock?

Short sleep duration is prevalent in modern society and may be contributing to type 2 diabetes prevalence. This review will explore the effects of sleep restriction on glycemic control, the mechanisms causing insulin resistance, and whether exercise can offset changes in glycemic control. Chronic sleep restriction may also contribute to a decrease in physical activity leading to further health complications.

The effect of sleep restriction, with or without high-intensity interval exercise, on behavioural alertness and mood state in young healthy males

Mood state and alertness are negatively affected by sleep loss, and can be positively influenced by exercise. However, the potential mitigating effects of exercise on sleep-loss-induced changes in mood state and alertness have not been studied comprehensively. Twenty-four healthy young males were matched into one of three, 5-night sleep interventions: normal sleep (NS; total sleep time (TST) per night = 449 ± 22 min), sleep restriction (SR; TST = 230 ± 5 min), or sleep restriction and exercise (SR + EX; TST = 235 ± 5 min, plus three sessions of high-intensity interval exercise (HIIE)). Mood state was assessed using the profile of mood states (POMS) and a daily well-being questionnaire. Alertness was assessed using psychomotor vigilance testing (PVT). Following the intervention, POMS total mood disturbance scores significantly increased for both the SR and SR + EX groups, and were greater than the NS group (SR vs NS; 31.0 ± 10.7 A.U., [4.4-57.7 A.U.], p = 0.020; SR + EX vs NS; 38.6 ± 14.9 A.U., [11.1-66.1 A.U.], p = 0.004). The PVT reaction times increased in the SR (p = 0.049) and SR + EX groups (p = 0.033) and the daily well-being questionnaire revealed increased levels of fatigue in both groups (SR; p = 0.041, SR + EX; p = 0.026) during the intervention. Despite previously demonstrated physiological benefits of performing three sessions of HIIE during five nights of sleep restriction, the detriments to mood, wellness, and alertness were not mitigated by exercise in this study. Whether alternatively timed exercise sessions or other exercise protocols could promote more positive outcomes on these factors during sleep restriction requires further research.

The effects of sleep disruption on metabolism, hunger, and satiety, and the influence of psychosocial stress and exercise: A narrative review

Sleep deficiency is a ubiquitous phenomenon among Americans. In fact, in the United States, ∼78% of teens and 35% of adults currently get less sleep than recommended for their age-group, and the quality of sleep appears to be getting worse for many. The consequences of sleep disruption manifest in a myriad of ways, including insulin resistance and disrupted nutrient metabolism, dysregulation of hunger and satiety, and potentially increased body weight and adiposity. Consequently, inadequate sleep is related to an increased risk of various cardiometabolic diseases, including obesity, diabetes, and heart disease. Exercise has the potential to be an effective therapeutic to counteract the deleterious effects of sleep disruption listed above, whereas chronic psychosocial stress may causally promote sleep disruption and cardiometabolic risk. Here, we provide a narrative review of the current evidence on the consequences of short sleep duration and poor sleep quality on substrate metabolism, circulating appetite hormones, hunger and satiety, and weight gain. Secondly, we provide a brief overview of chronic psychosocial stress and its impact on sleep and metabolic health. Finally, we summarise the current evidence regarding the ability of exercise to counteract the adverse metabolic health effects of sleep disruption. Throughout the review, we highlight areas where additional interrogation and future exploration are necessary.

Associations between self-reported sleep patterns and health, cognition and amyloid measures: results from the Wisconsin Registry for Alzheimer's Prevention

Previous studies suggest associations between self-reported sleep problems and poorer health, cognition, Alzheimer's disease pathology and dementia-related outcomes. It is important to develop a deeper understanding of the relationship between these complications and sleep disturbance, a modifiable risk factor, in late midlife, a time when Alzheimer's disease pathology may be accruing. The objectives of this study included application of unsupervised machine learning procedures to identify distinct subgroups of persons with problematic sleep and the association of these subgroups with concurrent measures of mental and physical health, cognition and PET-identified amyloid. Dementia-free participants from the Wisconsin Registry for Alzheimer's Prevention (n = 619) completed sleep questionnaires including the Insomnia Severity Index, Epworth Sleepiness Scale and Medical Outcomes Study Sleep Scale. K-means clustering analysis identified discrete sleep problem groups who were then compared across concurrent health outcomes (e.g. depression, self-rated health and insulin resistance), cognitive composite indices including episodic memory and executive function and, in a subset, Pittsburgh Compound B PET imaging to assess amyloid burden. Significant omnibus tests (P < 0.05) were followed with pairwise comparisons. Mean (SD) sample baseline sleep assessment age was 62.6 (6.7). Cluster analysis identified three groups: healthy sleepers [n = 262 (42.3%)], intermediate sleepers [n = 229 (37.0%)] and poor sleepers [n = 128 (20.7%)]. All omnibus tests comparing demographics and health measures across sleep groups were significant except for age, sex and apolipoprotein E e4 carriers; the poor sleepers group was worse than one or both of the other groups on all other measures, including measures of depression, self-reported health and memory complaints. The poor sleepers group had higher average body mass index, waist-hip ratio and homeostatic model assessment of insulin resistance. After adjusting for covariates, the poor sleepers group also performed worse on all concurrent cognitive composites except working memory. There were no differences between sleep groups on PET-based measures of amyloid. Sensitivity analyses indicated that while different clustering approaches resulted in different group assignments for some (predominantly the intermediate group), between-group patterns in outcomes were consistent. In conclusion, distinct sleep characteristics groups were identified with a sizable minority (20.7%) exhibiting poor sleep characteristics, and this group also exhibited the poorest concurrent mental and physical health and cognition, indicating substantial multi-morbidity; sleep group was not associated with amyloid PET estimates. Precision-based management of sleep and related factors may provide an opportunity for early intervention that could serve to delay or prevent clinical impairment.

The effects of camelina sativa oil and high-intensity interval training on liver function and metabolic outcomes in male type 2 diabetic rats

Objectives

The purpose of this study was to evaluate the independent and combined effects of camelina sativa oil and high-intensity interval training (HIIT) on liver function, and metabolic outcomes in streptozotocin-induced diabetic rats.

Methods

Forty male Wistar rats were randomly assigned to five equal groups (8 per group): Normal control (NC), diabetic control (DC), diabetic + camelina sativa oil (300 mg/kg by oral gavage per day; D + CSO), diabetic + HIIT (running on a treadmill 5 days/week for 8 weeks; D + HIIT), diabetic + camelina sativa oil + HIIT (D + CSO +  HIIT).

Results

In all three intervention groups (D + CSO, D + HIIT, and D + CSO + HIIT) compared to the DC, hepatic TNF-α, MDA, and histopathology markers, decreased and hepatic PGC-1α, and PPAR-γ increased (p < 0.05). However, the effect of D + CSO was greater than D + HIIT alone. Hepatic TG decreased significantly in D + HIIT and D + CSO + HIIT compared to other groups (p < 0.001). Fasting plasma glucose in all three intervention groups (D + CSO, D + HIIT, and D + CSO + HIIT) and HOMA-IR in D + CSO and D + CSO + HIIT were decreased compared to DC (p < 0.001). Only hepatic TAC and fasting plasma insulin remained unaffected in the three diabetic groups (p < 0.001). Overall, D + CSO + HIIT had the largest effect on all outcomes.

Conclusions

At the doses and treatment duration used in the current study, combination of CSO and HIIT was beneficial for reducing liver function and metabolic outcomes other than CSO and HIIT alone.

Effect of High-Intensity Interval Training Combined with Fasting in the Treatment of Overweight and Obese Adults: A Systematic Review and Meta-Analysis

Objectives: A systematic review and meta-analysis is conducted to compare the effects of high-intensity interval training (HIIT) combined with fasting (HIIT + fasting) and other interventions (HIIT alone, fasting alone, or normal intervention) in adults with overweight and obesity on body composition (body mass, body mass index (BMI), waist circumference (WC), percent fat mass (PFM), fat mass (FM), fat-free mass (FFM)), maximal oxygen uptake (VO_2peak), and glucose metabolism (fasting plasma glucose (FPG)), fasting plasma insulin (FPI)). Methods: The databases of PubMed, the Cochrane Library, Embace, Web of Science, CNKI, Wangfang Data, and CBM were searched from their inception to February 2022. Randomized controlled trials comparing the effects of HIIT + fasting and other interventions on adults with overweight and obesity were included in this meta-analysis. The risk of bias was assessed by the Cochrane risk of bias tool. The effect size was completed by using mean difference (MD) and standard deviation. If there were varying units or large differences among the included studies, the standardized mean difference (SMD) would be used. The certainty of evidence was evaluated using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE). Results: Nine randomized controlled trials with 230 overweight and obese adults were conducted in accordance with our inclusion criteria. The results of the meta-analysis revealed that compared to the control group HIIT + fasting had better effects on the body mass, WC, FM, and VO_2peak, while there were no significant differences in PFM, FFM, FPG, and FPI. Conclusions: Despite the number of included trials being small and the GRADE of all outcomes being very low, HIIT + fasting has a positive effect on the body composition of overweight and obese adults, and significantly improves VO_2peak. For adults with overweight and obesity who have long-term comorbidity, HIIT + fasting was a better way to improve FPG than HIIT alone or fasting alone. More studies are required to investigate different combinations of HIIT + fasting; and the safety of HIIT + fasting intervention on overweight and obese adults.

The Effect of Sleep Restriction, With or Without Exercise, on Skeletal Muscle Transcriptomic Profiles in Healthy Young Males

BACKGROUND

Inadequate sleep is associated with many detrimental health effects, including increased risk of developing insulin resistance and type 2 diabetes. These effects have been associated with changes to the skeletal muscle transcriptome, although this has not been characterised in response to a period of sleep restriction. Exercise induces a beneficial transcriptional response within skeletal muscle that may counteract some of the negative effects associated with sleep restriction. We hypothesised that sleep restriction would down-regulate transcriptional pathways associated with glucose metabolism, but that performing exercise would mitigate these effects.

METHODS

20 healthy young males were allocated to one of three experimental groups: a Normal Sleep (NS) group (8 h time in bed per night (TIB), for five nights (11 pm - 7 am)), a Sleep Restriction (SR) group (4 h TIB, for five nights (3 am - 7 am)), and a Sleep Restriction and Exercise group (SR+EX) (4 h TIB, for five nights (3 am - 7 am) and three high-intensity interval exercise (HIIE) sessions (performed at 10 am)). RNA sequencing was performed on muscle samples collected pre- and post-intervention. Our data was then compared to skeletal muscle transcriptomic data previously reported following sleep deprivation (24 h without sleep).

RESULTS

Gene set enrichment analysis (GSEA) indicated there was an increased enrichment of inflammatory and immune response related pathways in the SR group post-intervention. However, in the SR+EX group the direction of enrichment in these same pathways occurred in the opposite directions. Despite this, there were no significant changes at the individual gene level from pre- to post-intervention. A set of genes previously shown to be decreased with sleep deprivation was also decreased in the SR group, but increased in the SR+EX group.

CONCLUSION

The alterations to inflammatory and immune related pathways in skeletal muscle, following five nights of sleep restriction, provide insight regarding the transcriptional changes that underpin the detrimental effects associated with sleep loss. Performing three sessions of HIIE during sleep restriction attenuated some of these transcriptional changes. Overall, the transcriptional alterations observed with a moderate period of sleep restriction were less evident than previously reported changes following a period of sleep deprivation.

Obesity and polycystic ovary syndrome

The increased global prevalence of obesity over the last 40-years has driven a rise in prevalence of obesity-related co-morbidities, including polycystic ovary syndrome (PCOS). On a background of genetic susceptibility, PCOS often becomes clinically manifest following weight gain, commonly during adolescence. A common endocrinopathy affecting between 6%-10% of reproductive-age women, PCOS presents with the cardinal features of hyperandrogenism, reproductive and metabolic dysfunction. PCOS associates with insulin resistance, independently of (but amplified by) obesity. Insulin resistance in PCOS is characterized by abnormal post-receptor signalling within the phosphatidylinositol-kinase (PI3-K) pathway. Multiple factors (including most notably, weight gain) contribute towards the severity of insulin resistance in PCOS. Compensatory hyperinsulinaemia ensues, resulting in over-stimulation of the (intact) post-receptor mitogen-activated protein kinase (MAP-K) insulin pathway, with consequent implications for steroidogenesis and ovarian function. In this concise review, we explore the effects of weight gain and obesity on the pathogenesis of PCOS from the perspective of its three cardinal features of hyperandrogenism, reproductive and metabolic dysfunction, with a focus on the central mediating role of the insulin pathway. We also consider key lifestyle strategies for the effective management of obese and overweight women with PCOS.

Considerations for Maximizing the Exercise "Drug" to Combat Insulin Resistance: Role of Nutrition, Sleep, and Alcohol

Insulin resistance is a key etiological factor in promoting not only type 2 diabetes mellitus but also cardiovascular disease (CVD). Exercise is a first-line therapy for combating chronic disease by improving insulin action through, in part, reducing hepatic glucose production and lipolysis as well as increasing skeletal muscle glucose uptake and vasodilation. Just like a pharmaceutical agent, exercise can be viewed as a "drug" such that identifying an optimal prescription requires a determination of mode, intensity, and timing as well as consideration of how much exercise is done relative to sitting for prolonged periods (e.g., desk job at work). Furthermore, proximal nutrition (nutrient timing, carbohydrate intake, etc.), sleep (or lack thereof), as well as alcohol consumption are likely important considerations for enhancing adaptations to exercise. Thus, identifying the maximal exercise "drug" for reducing insulin resistance will require a multi-health behavior approach to optimize type 2 diabetes and CVD care.

Modest sleep restriction does not influence steps, physical activity intensity or glucose tolerance in obese adults

Sleep restriction (SR) (<6 h) and physical activity (PA) are risk factors for obesity, but little work has examined the inter-related influences of both risk factors. In a free-living environment, 13 overweight/obese adults were sleep restricted for five nights to 6 h time-in-bed each night, with and without regular exercise (45 min/65% VO₂ max; counterbalanced design). Two days of recovery sleep followed SR. Subjects were measured during a mixed meal tolerance test (MMT), resting metabolic rate, cognitive testing and fat biopsy (n=8). SR increased peak glucose response (+7.3 mg/dl, p = .04), elevated fasting non-esterified fatty acid (NEFA) concentrations (+0.1 mmol/L, p = .001) and enhanced fat oxidation (p < .001) without modifying step counts or PA intensity. Inclusion of daily exercise increased step count (+4,700 steps/day, p < .001) and decreased the insulin response to a meal (p = .01) but did not prevent the increased peak glucose response or elevated NEFA levels. The weekend recovery period improved fasting glucose (p = .02), insulin (p = .02), NEFA concentrations (p = .001) and HOMA-IR (p < .01) despite reduced steps (p < .01) and increased sedentary time (p < .01). Abdominal adipose tissue (AT) samples, obtained after baseline, SR and exercise, did not differ in lipolytic capacity following SR. Fatty acid synthase protein content tended to increase following SR (p = .07), but not following exercise. In a free-living setting, SR adversely affected circulating NEFAs, fuel oxidation and peak glucose response but did not directly affect glucose tolerance or AT lipolysis. SR-associated metabolic impairments were not mitigated by exercise, yet recovery sleep completely rescued its adverse effects on glucose metabolism.

Mechanisms of Insulin Resistance at the Crossroad of Obesity with Associated Metabolic Abnormalities and Cognitive Dysfunction

Obesity mediates most of its direct medical sequelae through the development of insulin resistance (IR). The cellular effects of insulin occur through two main postreceptor pathways that are the phosphatidylinositol 3-kinase (PI3-K) and the mitogen-activated protein kinase (MAP-K) pathways. Obesity-related IR implicates the PI3-K pathway that confers the metabolic effects of insulin. Numerous and complex pathogenic pathways link obesity with the development of IR, including chronic inflammation, mitochondrial dysfunction (with the associated production of reactive oxygen species and endoplasmic reticulum stress), gut microbiota dysbiosis and adipose extracellular matrix remodelling. IR itself plays a key role in the development of metabolic dysfunction, including hypertension, dyslipidaemia and dysglycaemia. Furthermore, IR promotes weight gain related to secondary hyperinsulinaemia, with a resulting vicious cycle of worsening IR and its metabolic sequelae. Ultimately, IR underlies obesity-related conditions such as type 2 diabetes mellitus (T2D) and polycystic ovary syndrome (PCOS). IR also underlies many obesity-related malignancies, through the effects of compensatory hyperinsulinaemia on the relatively intact MAP-K insulin pathway, which controls cellular growth processes and mitoses. Furthermore, the emergent data over recent decades support an important role of obesity- and T2D-related central IR in the development of cognitive dysfunction, including effects on hippocampal synaptic plasticity. Importantly, IR is largely reversible through the optimisation of lifestyle factors that include regular engagement in physical activity with the avoidance of sedentariness, improved diet including increased fibre intake and sleep sufficiency. IR lies at the key crossroad between obesity and both metabolic and cognitive dysfunction. Given the importance of IR in the pathogenesis of many 21st century chronic diseases and its eminent reversibility, it is important that we all embrace and facilitate optimised lifestyles to improve the future health and wellbeing of the populace.

Exercise mitigates sleep-loss-induced changes in glucose tolerance, mitochondrial function, sarcoplasmic protein synthesis, and diurnal rhythms

OBJECTIVE

Sleep loss has emerged as a risk factor for the development of impaired glucose tolerance. The mechanisms underpinning this observation are unknown; however, both mitochondrial dysfunction and circadian misalignment have been proposed. Because exercise improves glucose tolerance and mitochondrial function, and alters circadian rhythms, we investigated whether exercise may counteract the effects induced by inadequate sleep.

METHODS

To minimize between-group differences of baseline characteristics, 24 healthy young males were allocated into one of the three experimental groups: a Normal Sleep (NS) group (8 h time in bed (TIB) per night, for five nights), a Sleep Restriction (SR) group (4 h TIB per night, for five nights), and a Sleep Restriction and Exercise group (SR+EX) (4 h TIB per night, for five nights and three high-intensity interval exercise (HIIE) sessions). Glucose tolerance, mitochondrial respiratory function, sarcoplasmic protein synthesis (SarcPS), and diurnal measures of peripheral skin temperature were assessed pre- and post-intervention.

RESULTS

We report that the SR group had reduced glucose tolerance post-intervention (mean change ± SD, P value, SR glucose AUC: 149 ± 115 A.U., P = 0.002), which was also associated with reductions in mitochondrial respiratory function (SR: -15.9 ± 12.4 pmol O2.s-1.mg-1, P = 0.001), a lower rate of SarcPS (FSR%/day SR: 1.11 ± 0.25%, P < 0.001), and reduced amplitude of diurnal rhythms. These effects were not observed when incorporating three sessions of HIIE during this period (SR+EX: glucose AUC 67 ± 57, P = 0.239, mitochondrial respiratory function: 0.6 ± 11.8 pmol O2.s-1.mg-1, P = 0.997, and SarcPS (FSR%/day): 1.77 ± 0.22%, P = 0.971).

CONCLUSIONS

A five-night period of sleep restriction leads to reductions in mitochondrial respiratory function, SarcPS, and amplitude of skin temperature diurnal rhythms, with a concurrent reduction in glucose tolerance. We provide novel data demonstrating that these same detrimental effects are not observed when HIIE is performed during the period of sleep restriction. These data therefore provide evidence in support of the use of HIIE as an intervention to mitigate the detrimental physiological effects of sleep loss.

Impact of sleep deprivation and high-fat feeding on insulin sensitivity and beta cell function in dogs

AIMS/HYPOTHESIS

Insufficient sleep is increasingly recognised as a major risk factor for the development of obesity and diabetes, and short-term sleep loss in clinical studies leads to a reduction in insulin sensitivity. Sleep loss-induced metabolic impairments are clinically relevant, since reductions in insulin sensitivity after sleep loss are comparable to insulin sensitivity differences between healthy individuals and those with impaired glucose tolerance. However, the relative effects of sleep loss vs high-fat feeding in the same individual have not been assessed. In addition, to our knowledge no diurnal (active during the daytime) non-human mammalian model of sleep loss-induced metabolic impairment exists, which limits our ability to study links between sleep and metabolism.

METHODS

This study examined the effects of one night of total sleep deprivation on insulin sensitivity and beta cell function, as assessed by an IVGTT, before and after 9 months of high-fat feeding in a canine model.

RESULTS

One night of total sleep deprivation in lean dogs impaired insulin sensitivity to a similar degree as a chronic high-fat diet (HFD)(normal sleep: 4.95 ± 0.45 mU-1 l-1 min-1; sleep deprivation: 3.14 ± 0.21 mU-1 l-1 min-1; HFD: 3.74 ± 0.48 mU-1 l-1 min-1; mean ± SEM). Hyperinsulinaemic compensation was induced by the chronic HFD, suggesting adequate beta cell response to high-fat feeding. In contrast, there was no beta cell compensation after one night of sleep deprivation, suggesting that there was metabolic dysregulation with acute sleep loss that, if sustained during chronic sleep loss, could contribute to the risk of type 2 diabetes. After chronic high-fat feeding, acute total sleep deprivation did not cause further impairments in insulin sensitivity (sleep deprivation + chronic HFD: 3.28 mU-1 l-1 min-1).

CONCLUSIONS/INTERPRETATION

Our findings provide further evidence that sleep is important for metabolic health and establish a diurnal animal model of metabolic disruption during insufficient sleep.

Impaired Insulin Profiles Following a Single Night of Sleep Restriction: The Impact of Acute Sprint Interval Exercise

Experimental sleep restriction (SR) has demonstrated reduced insulin sensitivity in healthy individuals. Exercise is well-known to be beneficial for metabolic health. A single bout of exercise has the capacity to increase insulin sensitivity for up to 2 days. Therefore, the current study aimed to determine if sprint interval exercise could attenuate the impairment in insulin sensitivity after one night of SR in healthy males. Nineteen males were recruited for this randomized crossover study which consisted of four conditions-control, SR, control plus exercise, and sleep restriction plus exercise. Time in bed was 8 hr (2300-0700) in the control conditions and 4 hr (0300-0700) in the SR conditions. Conditions were separated by a 1-week entraining period. Participants slept at home, and compliance was assessed using wrist actigraphy. Following the night of experimental sleep, participants either conducted sprint interval exercise or rested for the equivalent duration. An oral glucose tolerance test was then conducted. Blood samples were obtained at regular intervals for measurement of glucose and insulin. Insulin concentrations were higher in SR than control (p = .022). Late-phase insulin area under the curve was significantly lower in sleep restriction plus exercise than SR (862 ± 589 and 1,267 ± 558; p = .004). Glucose area under the curve was not different between conditions (p = .207). These findings suggest that exercise improves the late postprandial response following a single night of SR.

Revisiting the Role of Exercise Countermeasure on the Regulation of Energy Balance During Space Flight

A body mass loss has been consistently observed in astronauts. This loss is of medical concern since energy deficit can exacerbate some of the deleterious physiological changes observed during space flight including cardiovascular deconditioning, bone density, muscle mass and strength losses, impaired exercise capacity, and immune deficiency among others. These may jeopardize crew health and performance, a healthy return to Earth and mission’s overall success. In the context of planning for planetary exploration, achieving energy balance during long-term space flights becomes a research and operational priority. The regulation of energy balance and its components in current longer duration missions in space must be re-examined and fully understood. The purpose of this review is to summarize current understanding of how energy intake, energy expenditure, and hence energy balance are regulated in space compared to Earth. Data obtained in both actual and simulated microgravity thus far suggest that the obligatory exercise countermeasures program, rather than the microgravity per se, may be partly responsible for the chronic weight loss in space. Little is known of the energy intake, expenditure, and balance during the intense extravehicular activities which will become increasingly more frequent and difficult. The study of the impact of exercise on energy balance in space also provides further insights on lifestyle modalities such as intensity and frequency of exercise, metabolism, and the regulation of body weight on Earth, which is currently a topic of animated debate in the field of energy and obesity research. While not dismissing the significance of exercise as a countermeasure during space flight, data now challenge the current exercise countermeasure program promoted and adopted for many years by all the International Space Agencies. An alternative exercise approach that has a minimum impact on total energy expenditure in space, while preventing muscle mass loss and other physiological changes, is needed in order to better understand the in-flight regulation of energy balance and estimate daily energy requirements. A large body of data generated on Earth suggests that alternate approaches, such as high intensity interval training (HIIT), in combination or not with sessions of resistive exercise, might fulfill such needs.