Effects of Physical Exercise Timing On Strength and Cardiometabolic Health

Study Overview
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Brief Summary
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Physical exercise is well known to improve human health. Current guidelines provide recommendations on the frequency, intensity, type and duration of exercise. However, they do not provide recommendations for the time of day, exercise should be performed. This is surprising considering that the influence of timing of behaviors such as sleep or nutrition as well as the impact of the circadian timing system on health are well documented. Further, there is evidence for diurnal variation in maximum performance which enables individuals to exercise with different intensities at different times of day, which in the long term might affect physical adaptations to exercise. Thus, this research study investigates if exercise timing impacts human health.

Official Title
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Effects of Physical Exercise Timing On Strength and Cardiometabolic Health

Conditions
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Physical Inactivity

Intervention / Treatment
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* Other: Physical Exercise Intervention


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: BMI 18.5 - 30 kg/m2 Exclusion Criteria: Structured resistance training within the last six months Ongoing shift work Irregular bedtime (> 2 hours variation in habitual bed time) Smoking Travels across more than two time zones within the last four weeks Inability to follow the study procedures (e.g. due to language barriers, psychological disorders, dementia, etc.) Known pregnancy or lactating women Participation in any other clinical trial within the last four weeks Medical condition that is a contra indicator for resistance training, endurance training, or exercising until maximum exhaustion including insufficiently controlled blood pressure (systolic > 170 mmHg, diastolic > 100 mmHg), ongoing cancer treatment, unstable angina pectoris, uncontrolled bradyarrhythmia or tachyarrhythmia, severe uncorrected valvular heart disease, clinically relevant acute infection, any form of musculoskeletal injury, orthopedic problems or decompensated cardiovascular disease Insulin dependent diabetes Participants using metformin

Ages Eligible for Study
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Minimum Age: 60 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| No Intervention: Control<br>Single life-style coaching session | |
| Experimental: Exercise Time 1<br>Physical exercise intervention taking place at one time of the day | Other: Physical Exercise Intervention<br>* Two strength training session per week and one endurance training session per week<br>|
| Experimental: Exercise Time 2<br>Physical exercise intervention taking place at another time of day | Other: Physical Exercise Intervention<br>* Two strength training session per week and one endurance training session per week<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Maximum strength | Mean value of the maximum isometric leg strength assessed at four different times of the day with an isokinetic dynamometer. | Pre-Intervention (i.e. 1 to 28 days before the first training session of the exercise intervention) and Post-Intervention (i.e. 1 to 28 days after the last training session of the exercise intervention) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Glucose control | 3-h postprandial area under the curve for glucose after an oral glucose tolerance test | Pre-Intervention (i.e. 1 to 28 days before the first training session of the exercise intervention) and Post-Intervention (i.e. 1 to 28 days after the last training session of the exercise intervention) | 
| Body composition | total body fat mass assessed with DXA | Pre-Intervention (i.e. 1 to 28 days before the first training session of the exercise intervention) and Post-Intervention (i.e. 1 to 28 days after the last training session of the exercise intervention) | 
| Cardiorespiratory fitness | VO2max assessed with cardiopulmonary exercise test | Pre-Intervention (i.e. 1 to 28 days before the first training session of the exercise intervention) and Post-Intervention (i.e. 1 to 28 days after the last training session of the exercise intervention) |