The multi-omics mechanisms

behind the promotion of overall health and disease prevention through regular exercise

Background

In May of this year, the Molecular Transducers of Physical Activity Consortium (MoTrPAC) published an important study exploring the multi-omics mechanisms behind the promotion of overall health and disease prevention through regular exercise. In this study, they conducted an eight-week endurance training regimen in a mouse model and identified thousands of shared and tissue-specific molecular changes in whole blood and plasma. The research also uncovered gender differences across various tissues. Through time-course multi-omics and multi-tissue analysis, the study revealed broad biological insights into the adaptive responses to endurance training, including extensive regulation of immune, metabolic, stress response, and mitochondrial pathways. Many of these changes are closely linked to human health, including non-alcoholic fatty liver disease, inflammatory bowel disease, cardiovascular health, as well as tissue damage and recovery. The data and analysis provided in this study will serve as a valuable resource for understanding and exploring the multi-tissue molecular effects of endurance training.

The time dynamics of the multi-omics response to endurance exercise training refer to the changes in various biomolecules and their functions over time under the influence of sustained and regular physical activity aimed at improving cardiovascular, respiratory, and muscle endurance. This research field is highly interdisciplinary, involving genomics (gene expression), transcriptomics (RNA levels), proteomics (protein levels), metabolomics (metabolite levels), and other omics fields, which together provide a comprehensive view of physiological adaptation at the molecular level.

1. Genomics and Transcriptomics:

Under the influence of endurance training, gene expression profiles change, with certain genes being upregulated (increased expression) while others are downregulated (decreased expression). These changes can affect pathways related to energy metabolism, inflammation, muscle repair, and growth.

The timing and duration of these changes may vary. Some effects are immediate, while others develop over the long term as the body gradually adapts to the training stimulus.

2. Proteomics:

Changes in protein content in muscles and other tissues can reflect both short-term and long-term adaptations. For example, in trained individuals, an increase in enzymes related to aerobic metabolism, such as citrate synthase or cytochrome c oxidase, is commonly observed.

Proteins related to stress responses, antioxidant defense, and muscle contraction may also undergo significant changes with endurance training.

3. Metabolomics:

Endurance exercise leads to changes in metabolic pathways, affecting the concentrations of various metabolites. This includes alterations in amino acid, carbohydrate, and lipid metabolism, reflecting the body's adaptation to increased energy demands and more efficient fuel utilization.

With training, metabolic flexibility (the ability to switch between different fuel sources, such as from carbohydrates to fats) is often enhanced.

4. Epigenetics:

Epigenetic modifications, such as DNA methylation and histone modifications, can be influenced by endurance training. These changes can alter gene expression without changing the underlying DNA sequence, potentially leading to long-lasting adaptations.

5. Microbiome:

There is growing interest in how endurance exercise affects and contributes to the benefits of the gut microbiome. Changes in the composition and function of the gut microbiota have been linked to improvements in metabolic health and performance.

6. Temporal Dynamics of Multi-Omic Responses to Endurance Exercise Training:

Acute Response:Immediately following exercise, there is a transient increase in markers of muscle damage, inflammation, and oxidative stress, along with changes in substrate utilization.

Short-Term Adaptation:Within a few days to weeks, as training continues, the body begins to adapt. This includes enhanced mitochondrial biogenesis, improved insulin sensitivity, and adjustments in gene expression related to energy metabolism.

Long-Term Adaptation:After months to years of sustained training, profound changes occur, including structural and functional modifications in the heart and skeletal muscle, as well as improvements in overall metabolic health.

Summary

Understanding these temporal dynamics is crucial for optimizing training regimens, preventing overtraining, and developing personalized approaches to enhance athletic performance and health. Research in this field often includes longitudinal studies, analyzing participants' multi-omic profiles at defined points before, during, and after training periods to identify key time points and adaptation patterns.

Experimental Methods:

1. Animal Adaptation:

In the experiment, male and female Fischer 344 rats underwent at least four weeks of environmental adaptation before starting endurance training to reduce stress. The rats were adapted to a reverse light/dark cycle, with lights off at 9:00 AM and on at 9:00 PM, so that treadmill training occurred during the rats' normal active phase. Rats were housed two per cage in ventilated racks with bedding made of shredded white pine.

2. Diet and Environmental Conditions:

The animals were free to eat with the following caloric composition: 21.196% protein, 14.774% fat (ether extract), and 64.030% carbohydrates. The animal room was monitored daily, with temperatures maintained between 68-77°F (20-25°C) and relative humidity between 25-55%. Red lights were used during the rats' dark cycle to provide sufficient illumination for routine animal care, handling, and training.

3. Treadmill Exercise:

The treadmill exercise was conducted on a five-channel rat treadmill. All animal handling and exercise occurred during the rats' active dark phase. After arrival, rats were acclimated to the reverse light/dark cycle for at least 10 days. Following an initial adaptation period, rats underwent a 12-day treadmill familiarization protocol to get accustomed to the treadmill and identify rats that were uncooperative. Rats that could not run continuously for 5 minutes at 10 m/min with a 0° incline were classified as uncooperative and removed from the study. Rats that successfully completed the 12-day familiarization were entered into a rat database and randomly assigned to control or training groups to ensure equal average weights between groups.

4. Random Allocation of Rats by Age and Sex

The rats at 8 weeks of age were randomly assigned to the control or training group based on sex and body weight quartiles. The rats at 4 weeks of age were directly assigned to the control group without randomization. Rats at 1 and 2 weeks of age were randomly assigned to the 1-week or 2-week training group based on sex and body weight quartiles.

5. Training Protocol:

Endurance training started at 6 months of age for both male and female rats and lasted for 1, 2, 4, or 8 weeks. At this age, the lean muscle mass of the strain had plateaued. Rats trained on a treadmill 5 days per week, following a progressive training protocol that aimed for approximately 70% of the rats' maximal oxygen uptake (VO2max). The initial treadmill speed was based on VO2max measurements taken after the familiarization phase and prior to training. Training occurred during the rats' dark phase, for 5 consecutive days each week, starting no earlier than 10:00 AM and ending no later than 5:00 PM.

6. Training Intensification:

The training protocol started with a 5° incline, 13 m/min for males, 16 m/min for females, and a 20-minute duration. As detailed in Table 1, the exercise duration increased by one minute each day until day 31 (week 7), when the duration reached 50 minutes. The treadmill incline started at 5° and increased to 10° by week 3, and remained at 10° for the remainder of the training period. Treadmill speed increased at the start of weeks 2, 4, 5, 6, and 7. From week 7, speed, incline, and duration were fixed and maintained for the final 10 days to ensure steady-state training. If a rat failed to complete at least 4 days of training per week, it was removed from the study and euthanized.

7. Control Group:

Rats in the control group were placed on a stationary treadmill (0 m/min) for 15 minutes per day, 5 days per week, following a schedule similar to the 8-week training group. Control animals were age-matched with the 8-week training group. It is important to note that rats between 6 and 9 months old had reached maturity and exhibited minimal physiological differences before the age of 12 months.

Body Composition Analysis

Body composition was measured for all rats 13 days before the training period began using a body composition analyzer. This device was used to measure lean tissue, body fat, and body fluid in awake, live animals. For rats in the 4-week and 8-week training groups, body composition was re-measured 5 days before tissue harvesting.

VO2max Analysis

VO2max was assessed for all rats before training, and for the 4-week and 8-week exercise groups at the end of the respective training periods. Rats were adapted to the treadmill for two days before testing on a single-lane closed treadmill. On the test day, the rats were placed on the treadmill, and once their oxygen consumption stabilized, testing commenced. The test began with a 15-minute warm-up at 9 m/min and a 0° incline. After warming up, the incline was increased to 10° and the treadmill speed increased by 1.8 m/min every 2 minutes.

Shock was used only if necessary, and only if the rat stopped running and sat in the shock area. The test ended if the rat sat in the shock area three times consecutively and did not respond to the increased shock. After the test, rats were removed from the treadmill, and blood was drawn from the tail to measure lactate.

The criteria for achieving VO2max included: despite increasing workload, oxygen uptake plateauing, respiratory exchange ratio exceeding 1.05, and blood lactate levels ≥6 mM.

Tow-Int Tech Animal Metabolic Treadmill

The Tow-Int Tech Animal Metabolic Treadmill is specially designed for animal respiratory metabolism measurement. The metabolic treadmill features a closed design and can monitor oxygen consumption, VO2max, CO2 production, and respiratory metabolic rate during animal exercise. This treadmill is an essential experimental device for studies on animal physical endurance, exercise-induced injuries, exercise nutrition, pharmaceuticals, and physiological and pathological responses to exercise.

Currently, Tow-Int Tech is conducting a trial program for the animal metabolic treadmill. For more details, please contact us using the following contact information.