Chrono-exercise: Time-of-day-dependent physiological responses to exercise

Modeling climate change effects on some biochemical parameters in horse

Changes in the global climate pose a severe threat to human and animal welfare and productivity. Total proteins (TP), globulins (GLOB), albumins (ALB), alkaline phosphatase (ALP), creatine kinase (CK), lactate dehydrogenase (LDH), aspartate aminotransferase (AST), blood urea nitrogen (BUN), γ-glutamyl transferase (GGT), and creatinine (CREA) were evaluated during a three-year monitoring period (2021-23) on 16 Thoroughbred retired mares from the regional Golkoy Breeding Farm in Kastamonu- Turkey. The following thermal and hygrometric parameters were gathered: ambient temperature (AT), relative humidity (RH) and ventilation (VT), and the Temperature-Humidity Index (THI) was then calculated. Blood samples were collected on the first of each month from January 2021 to December 2023 and the obtained serum was used for the analysis, variations in environmental parameters were correlated to changes in biochemical profile. Two-way for repeated measure ANOVA showed a significant effect of month for AT (<0.0001), RH (<0.0001), and THI (<0.0001), and on TP (p < 0.001), GLOB (p < 0.001), ALB (p < 0.0001), ALP (p < 0.01), CK (p < 0.01), LDH (p < 0.001), AST (p < 0.0001), BUN (p < 0.0001), GGT (p < 0.0001), and CREA (p < 0.0001). ALP, CK, LDH, AST, and BUN values increased during the hottest periods, while GGT showed decreasing values during the summer. CREA showed positive correlation with AT, and LDH and CREA exhibited negative correlation with RH. These results may be useful for the monitoring of horses' physiological conditions as a result of climate change.

The effects of acute bouts of exercise in fasted vs. fed states on glucose and lipid metabolism in healthy adults: A systematic review and meta-analysis of randomized clinical trials

AIMS

Exercise while fasted is often promoted as beneficial for lipid metabolism, as it may confer superior metabolic adaptations compared with exercise performed in the fed state. The aim of this systematic review and meta-analysis was to determine the effects of acute exercise in fasted versus fed states on glucose and lipid metabolism in healthy adults.

DATA EXTRACTION

A systematic review and meta-analysis was performed by searching PubMed, Scopus, and Web of Science databases up to July 2023, for randomized clinical trials that determined the effects of exercise in fasted vs. fed states on glucose and lipid metabolism (serum glucose, insulin, triacylglycerol, free fatty acid (FFA) concentrations, and respiratory exchange ratio (RER)) in healthy adults. Meta-analyses were conducted to determine weighted mean differences (WMD) and 95 % confidence intervals.

ANALYSIS

The current meta-analysis included 28 studies with a total sample of 302 healthy adults, with exercise durations ranging from 36 to 150 min. Acute exercise performed while fasted was associated with significant increases from pre- to post-exercise in fasted serum glucose [WMD = 0.263 mmol/L, p = 0.009] and insulin [WMD = 8.84 mU/mL, p = 0.001], and significantly decreases in FFA [WMD = -0.121 mmol/L, p = 0.019] when compared with exercise in the fed state. However, no significant differences were reported for changes in triacylglycerol or RER from pre- to post-exercise when comparing fasted vs. fed states.

CONCLUSION

When compared with exercise in the fed state, exercise performed while fasted was associated with larger increases in glucose and insulin levels, along with larger decreases in FFA levels. Thus, our results do not suggest that acute fasted exercise is necessarily better for glucose or lipid metabolism when compared with exercise performed in the fed state. It is possible, albeit unlikely, that acute bouts of exercise performed while fasted may result in some degree of metabolic impairment.

Timing of exercise differentially impacts adipose tissue gain in male adolescent rats

OBJECTIVE

Circadian rhythms of metabolic, hormonal, and behavioral fluctuations and their alterations can impact health. An important gap in knowledge in the field is whether the time of the day of exercise and the age of onset of exercise exert distinct effects at the level of whole-body adipose tissue and body composition. The goal of the present study was to determine how exercise at different times of the day during adolescence impacts the adipose tissue transcriptome and content in a rodent model.

METHODS

Rats were subjected to one of four conditions during their adolescence: early active phase control or exercise (EAC or EAE; ZT13), and late active phase control or exercise (LAC or LAE; ZT23). The effects of exercise timing were assessed at the level of subcutaneous and visceral adipose tissue transcriptome, body composition, hypothalamic expression of orexigenic and anorexigenic genes, blood serum markers and 24-hour core body temperature patterns.

RESULTS

We found that late active phase exercise (ZT23) greatly upregulated pathways of lipid synthesis, glycolysis and NADH shuttles in LAE rats, compared to LAC or EAE. Conversely, LAE rats showed notably lower content of adipose tissue. In addition, LAE rats showed signs of impaired FGF21-adiponectin axis compared to other groups.

CONCLUSIONS

Finally, LAE rats showed higher post-exercise core body temperature compared to other groups. Our results thus indicate that our exercise protocol induced an unusual effect characterized by enhanced lipid synthesis but reduced adipose tissue content in late active phase but not early active phase exercise during adolescence.

The association of activity patterns on female reproductive diseases: a prospective cohort study of UK biobank

OBJECTIVE

Little is known about the role of timing of physical activity in female reproductive disorders. These disorders include polycystic ovary syndrome (PCOS), heavy menstrual bleeding (HMB), endometriosis, infertility, and pregnancy-related disorders. This study aims to investigate the associations of activity patterns with female reproductive diseases.

METHODS

A total of 49,540 female participants from the UK Biobank with valid accelerometer data were enrolled at baseline. Activity patterns were defined based on the timing of moderate-to-vigorous intensity physical activity (MVPA) throughout the day. Participants were categorized into four groups according to the timing of their MVPA: "morning, evening, mixed, midday-afternoon", with the midday-afternoon group serving as the reference. Cox proportional hazards models were utilized to evaluate the association between activity patterns and female reproductive diseases.

RESULTS

During a median follow-up of 12.6 years, a total of 1044 cases of female reproductive diseases were documented. After adjustment for potential confounders, compared to women with midday-afternoon exercise, women with morning exercise and mixed-timing exercise were associated with lower risks for female reproductive diseases (HRmorning=0.81, 95% CI: 0.67-0.98; HRmixed=0.79, 95% CI: 0.69-0.91, P-trend < 0.05). Moreover, morning exercise and mixed-timing exercise had lower risks of PCOS (HRmorning=0.38, 95% CI: 0.15-0.97; HRmixed=0.27, 95% CI: 0.13-0.57, P-trend<0.001), and mixed-timing exercise was associated with a lower risk for HMB (HRmixed=0.81, 95% CI: 0.70-0.95, P-trend < 0.05), compared with the reference group.

CONCLUSIONS

Compared with midday-afternoon group, morning and mixed MVPA timing groups, but not evening group, were associated with decreased risks for female reproductive diseases and PCOS. In addition, we found that women with mixed MVPA timing exercise had a lower risk of HMB, compared with the reference group.

Temporal patterns of energy intake and physical activity and cross-sectional associations with body weight status in children and adolescents: results from the Portuguese National Food, Nutrition and Physical Activity Survey 2015-2016

Temporal energy intake (EI) and physical activity (PA) patterns may be associated with obesity. We aimed to derive and characterise temporal EI and PA patterns, and assess their cross-sectional association with weight status, in 6-to-14-year-old Portuguese participants of the National Food, Nutrition and Physical Activity Survey 2015-2016. We extracted times and EI of all eating occasions from two 1-d food diaries/24-h recalls, while types and times of PA from 4-d PA diaries. We derived EI patterns (n 714) and PA patterns (n 595), using, respectively, a hierarchical and K-means cluster analysis, considering the average proportion of total daily EI (%TEI) and PA intensity (%TPA), within each 2-h interval across the 24-h day. Patterns were labelled based on the 2-h intervals of %TEI/TPA peaks. We assessed the association between patterns and overweight or obesity (BMI z-score ≥ +1 sd) using adjusted logistic regressions (OR (95 % CI)). Three EI patterns emerged: 1 - 'Early afternoon and early evening'; 2 - 'Early afternoon and late evening'; and 3 - 'Late morning, early and mid-afternoon and late evening'. EI Pattern 3 v. Pattern 1 was negatively associated with overweight or obesity (0·49 (0·26, 0·92)). PA Pattern 1 - 'Late morning, mid-afternoon and early evening' v. Pattern 2 - 'Late afternoon', was not associated with weight status (0·95 (0·65, 1·38)). A daily EI pattern with more and even %TEI peaks at earlier daytime periods, rather than fewer and higher, may be negatively associated with overweight or obesity amongst this population whereas the identified PA patterns might have no relationship.

Climate change impact on blood haemogram in the horse: a three-year preliminary study

Introduction

The global climatic changes pose a substantial threat to the well-being and productivity of both humans and animals.

Methods

This study examined the impact of climate changes during different seasons over a 3-year monitoring period (2021-2023) on various blood parameters including, white blood cells (WBC), neutrophils, basophils, eosinophils, lymphocytes, and monocytes, hematocrit (HCT), hemoglobin (HGB), red blood cells (RBC), platelets (PLT), mean corpuscular hemoglobin concentration (MCHC), mean corpuscular volume (MCV), and mean corpuscular hemoglobin (MCH). The study focused on 25 Thoroughbred mares located in Kastamonu-Türkiye. Thermal and hygrometric parameters, including ambient temperature, relative humidity, and ventilation, were collected. Subsequently, Temperature-Humidity index (THI) was computed. Blood samples were collected on the first day of every month from January 2021 to December 2023 and used for a complete blood count analysis. Between 2021 and 2023, changes in environmental indicators were correlated to changes in hematological parameters.

Results

Two-way for repeated measures ANOVA revealed a significant seasonal fluctuation (<0.0001) in ambient temperature, relative humidity, and THI. There was a reduction in RBC (<0.01), and MCH (<0.01) every year, HGB (<0.0001) in summer 2021, 2022 and in summer and autumn 2023. HCT (<0.0001), MCV (<0.01), showed decreasing values in autumn 2022 and 2023. MCHC values showed increasing values in July and August 2021, 2022 and in June 2023. WBC levels increased throughout the spring periods of 2021 and 2022. In April 2021, there were elevated levels of lymphocytes and monocytes (<0.0001) respectively.

Discussion

These findings could be helpful to promote the monitoring of physiological status both for the assessment of welfare status and for diagnostic purposes for the evaluation of possible disease outbreaks due to climate change in veterinary medicine.

Impact of lifestyle moderate-to-vigorous physical activity timing on glycemic control in sedentary adults with overweight/obesity and metabolic impairments

OBJECTIVE

Moderate-to-vigorous physical activity (MVPA) improves glucose levels; however, whether its timing affects daily glycemic control remains unclear. This study aims to investigate the impact of lifestyle MVPA timing on daily glycemic control in sedentary adults with overweight/obesity and metabolic impairments.

METHODS

A total of 186 adults (50% women; age, 46.8 [SD 6.2] years) with overweight/obesity (BMI, 32.9 [SD 3.5] kg/m2) and at least one metabolic impairment participated in this cross-sectional study. MVPA and glucose patterns were simultaneously monitored over a 14-day period using a triaxial accelerometer worn on the nondominant wrist and a continuous glucose-monitoring device, respectively. Each day was classified as "inactive" if no MVPA was accumulated; as "morning," "afternoon," or "evening" if >50% of the MVPA minutes for that day were accumulated between 0600 and 1200, 1200 and 1800, or 1800 and 0000 hours, respectively; or as "mixed" if none of the defined time windows accounted for >50% of the MVPA for that day.

RESULTS

Accumulating >50% of total MVPA during the evening was associated with lower 24-h (mean difference [95% CI], -1.26 mg/dL [95% CI: -2.2 to -0.4]), diurnal (-1.10 mg/dL [95% CI: -2.0 to -0.2]), and nocturnal mean glucose levels (-2.16 mg/dL [95% CI: -3.5 to -0.8]) compared with being inactive. This association was stronger in those participants with impaired glucose regulation. The pattern of these associations was similar in both men and women.

CONCLUSIONS

These findings suggest that timing of lifestyle MVPA is significant. Specifically, accumulating more MVPA during the evening appears to have a beneficial effect on glucose homeostasis in sedentary adults with overweight/obesity and metabolic impairments.

Chronophysiology of domestic animals

This review highlights recent findings on biological rhythms and discusses their implications for the management and production of domestic animals. Biological rhythms provide temporal coordination between organs and tissues in order to anticipate environmental changes, orchestrating biochemical, physiological and behavioural processes as the right process may occur at the right time. This allows animals to adapt their internal physiological functions, such as sleep-wake cycles, body temperature, hormone secretion, food intake and regulation of physical performance to environmental stimuli that constantly change. The study and evaluation of biological rhythms of various physiological parameters allows the assessment of the welfare status of animals. Alteration of biological rhythms represents an imbalance of the state of homeostasis that can be found in different management conditions.

Lighting the way: Exploring diurnal physical performance differences in school-aged visually impaired children and adolescents

Circadian rhythms play a pivotal role in governing various physiological processes, including physical performance. However, in individuals deprived of light perception, such as the blind, these circadian rhythms face disruption. This study aimed to explore the influence of disturbed circadian rhythms on short-term maximal physical performance in children and adolescents with visual impairment. Forty-five volunteers participated in this study, comprising 17 blind, 13 visually impaired, and 15 sighted participants. The participants underwent a series of tests assessing maximal isometric strength performance across two days. To mitigate the influence of morning session fatigue on the evening results, each participant group performed in two separate testing sessions (i.e. in the morning (7:00 h) and in the evening (17:00 h)) on non-consecutive days in a randomized and counterbalanced setting, with approximately 36 h of recovery time between sessions. To mitigate the impact of inter-individual differences on mean values and to account for the influence of age and sex on the studied variables, data were normalized. The outcomes revealed a significant diurnal variation in maximal isometric strength performance among sighted individuals, with peak performance observed in the evening. This pattern aligns with their well-entrained circadian rhythm. In contrast, blind and visually impaired individuals did not display significant diurnal variation, signaling disrupted circadian rhythms due to the absence of light perception. These findings emphasize the crucial consideration of circadian rhythms in assessments of physical performance, especially among participants with visual impairments.

Sensor-Based Assessment of Time-of-Day-Dependent Physiological Responses and Physical Performances during a Walking Football Match in Higher-Weight Men

Monitoring key physiological metrics, including heart rate and heart rate variability, has been shown to be of value in exercise science, disease management, and overall health. The purpose of this study was to investigate the diurnal variation of physiological responses and physical performances using digital biomarkers as a precise measurement tool during a walking football match (WFM) in higher-weight men. Nineteen males (mean age: 42.53 ± 12.18 years; BMI: 33.31 ± 4.31 kg·m-2) were engaged in a WFM at two different times of the day. Comprehensive evaluations of physiological parameters (e.g., cardiac autonomic function, lactate, glycemia, and oxygen saturation), along with physical performance, were assessed before, during, and after the match. Overall, there was a significant interaction (time of day x WFM) for mean blood pressure (MBP) (p = 0.007) and glycemia (p = 0.039). Glycemia decreased exclusively in the evening after WFM (p = 0.001), while mean blood pressure did not significantly change. Rating of perceived exertion was significantly higher in the evening than in the morning (p = 0.04), while the heart rate recovery after 1 min (HRR60s) of the match was lower in the evening than in the morning (p = 0.048). Overall, walking football practice seems to be safe, whatever the time of day. Furthermore, HRR60, glycemia, and (MBP) values were lower in the evening compared to the morning, suggesting that evening exercise practice could be safer for individuals with higher weight. The utilization of digital biomarkers for monitoring health status during WFM has been shown to be efficient.

Circadian regulation in aging: Implications for spaceflight and life on earth

Alterations in the circadian system are characteristic of aging on Earth. With the decline in physiological processes due to aging, several health concerns including vision loss, cardiovascular disorders, cognitive impairments, and muscle mass loss arise in elderly populations. Similar health risks are reported as "red flag" risks among astronauts during and after a long-term Space exploration journey. However, little is known about the common molecular alterations underlying terrestrial aging and space-related aging in astronauts, and controversial conclusions have been recently reported. In light of the regulatory role of the circadian clock in the maintenance of human health, we review here the overlapping role of the circadian clock both on aging on Earth and spaceflight with a focus on the four most affected systems: visual, cardiovascular, central nervous, and musculoskeletal systems. In this review, we briefly introduce the regulatory role of the circadian clock in specific cellular processes followed by alterations in those processes due to aging. We next summarize the known molecular alterations associated with spaceflight, highlighting involved clock-regulated genes in space flown Drosophila, nematodes, small mammals, and astronauts. Finally, we discuss common genes that are altered in terms of their expression due to aging on Earth and spaceflight. Altogether, the data elaborated in this review strengthen our hypothesis regarding the timely need to include circadian dysregulation as an emerging hallmark of aging on Earth and beyond.

The effects of physical exercise therapy on weight control: its regulation of adipocyte physiology and metabolic capacity

Factors associated with increased body mass, including dyslipidemia, hypertension, insulin resistance, vascular endothelial dysfunction and sleep disorders, may contribute to the exacerbation of cardiovascular disease. These health problems associated with obesity are caused by accumulated metabolism and physical and emotional stress. Lifestyle, especially exercise, is a major therapeutic strategy for the treatment and management of obesity-induced metabolic problems. Metabolic disease often co-occurs with abdominal obesity. Exercise is necessary for the treatment of obesity, diabetes and cardiovascular disease. A potential benefit of exercise is to promote fat burning and energy use increases both during exercise itself and in the post-exercise period. Exercise suppresses basal metabolic rate and also has many health benefits. Why should we exercise to lose weight? Does physical activity help lower blood pressure, blood cholesterol, and blood sugar? In this article, we review the positive effects of physical exercise on weight maintenance and weight loss, and the effectiveness of physical exercise on the treatment and prevention of metabolic syndrome.

Exercise Timing Matters for Glycogen Metabolism and Accumulated Fat Oxidation over 24 h

Due to increasingly diverse lifestyles, exercise timings vary between individuals: before breakfast, in the afternoon, or in the evening. The endocrine and autonomic nervous systems, which are associated with metabolic responses to exercise, show diurnal variations. Moreover, physiological responses to exercise differ depending on the timing of the exercise. The postabsorptive state is associated with greater fat oxidation during exercise compared to the postprandial state. The increase in energy expenditure persists during the post-exercise period, known as "Excess Post-exercise Oxygen Consumption". A 24 h evaluation of accumulated energy expenditure and substrate oxidation is required to discuss the role of exercise in weight control. Using a whole-room indirect calorimeter, researchers revealed that exercise performed during the postabsorptive state, but not during the postprandial state, increased accumulated fat oxidation over 24 h. The time course of the carbohydrate pool, as estimated by indirect calorimetry, suggests that glycogen depletion after postabsorptive exercise underlies an increase in accumulated fat oxidation over 24 h. Subsequent studies using 13C magnetic resonance spectroscopy confirmed that the variations in muscle and liver glycogen caused by postabsorptive or postprandial exercise were consistent with indirect calorimetry data. These findings suggest that postabsorptive exercise alone effectively increases 24 h fat oxidation.