Notes on Physical Activity, Cardiovascular Health, and Gene Adaptation

Genetic Adaptation to Physical Activity

  • Most protein-coding genes in the human genome have undergone selection pressure during the pre-industrial era when physical activity was vital for survival.

  • Humans are genetically adapted to perform physical activity regularly.

Mismatch in Modern Life

  • A lack of physical activity, prevalent in today's society, produces chronic maladaptation due to the mismatch between our biological needs and current lifestyles.

Assessing Physical Activity Levels

  • Researchers use the Physical Activity Ratio (PAR) to measure physical activity levels:

  • PAR = Total daily energy expenditure (kJ/min) / Basal metabolic rate (kJ/min)

  • PAR values:

  • 1.40–1.69: Inactive to lightly active (Western societies)

  • 1.70–1.99: Moderately active

  • ≥2.00: Vigorously active

Examples of Active Traditional Populations

  1. Hadza People (Tanzania):

  • Average PAR: 1.78 (women), 2.26 (men)

  • Average 950 min/week of moderate-to-vigorous physical activity (MVPA), well above the WHO recommendation of 150 min/week.

  1. Tsimané People (Bolivia):

  • Low cardiovascular disease (CVD) risk factors

  • Average PAR: 2.02–2.15 (men), 1.73–1.85 (women)

  1. Kitava (Papua New Guinea):

  • Estimated PAR: 1.70

  • Low incidence of chronic diseases like stroke and diabetes.

Importance of Physical Activity

  • Moderate-to-Vigorous Physical Activity (MVPA): Any activity yielding ≥3 metabolic equivalents.

  • WHO recommends:

  • 150 min of MVPA each week for adults

  • 60 min for children/adolescents.

  • Regular exercise is essential for CVD prevention and management, showing direct physiological benefits beyond traditional risk factors.

Physiological Benefits of Regular Exercise

  • Cardiovascular Health:

  • Regular exercise improves vascular function and structure independent of traditional risk factors.

  • Exercise attributes reduce chronic inflammation via muscle-derived myokines, improving cardiac function and autonomic balance.

  • Myokines promote muscle regeneration and counteract aging-related muscle loss.

  • Muscle and Strength Factors:

  • Loss of muscle strength/mass significantly correlates with CVD. Resistance training helps reverse these changes, improving overall fitness.

  • Resistance training is often overlooked despite its potent capacity to enhance strength and function, especially in the elderly.

Exercise and Autonomic Balance

  • Regular exercise improves heart rate variability (HRV) and reduces risks from arrhythmias. Enhanced vagal tone contributes to better cardiac function.

High-Intensity Interval Training (HIIT)

  • A popular exercise modality that is time-efficient (<20 mins/session) but induces strong biological adaptations beneficial for CVD prevention.

Benefits of Different Exercise Modalities

  • Aerobic Exercise:

  • Improves cardiovascular function and can lower the risk of mortality.

  • Resistance Training:

  • Essential for maintaining muscle strength, particularly in older adults with CVD risk factors.

Gut Microbiota and Exercise

  • Regular exercise positively modulates gut microbiota, promoting healthy diversity and reducing inflammation, which correlates with better cardiovascular outcomes.

Conclusions & Recommendations

  • Regular physical activity instills numerous health benefits independent of traditional CVD risk factors.

  • Strength training should be included in exercise prescriptions, particularly for aging populations to promote cardiovascular and functional health.

Genetic Adaptation to Physical Activity

  • The majority of protein-coding genes in the human genome have undergone selection pressure during the pre-industrial era, a time when physical activity was vital for survival and day-to-day functioning. This has resulted in significant genetic adaptations that enhance our ability to perform regular physical activity.

  • The human body is intrinsically designed to engage in frequent physical activity—a trait that is deeply embedded in our genetic makeup. These adaptations are evident not only in muscle composition and strength but also in cardiovascular endurance and metabolic efficiency, which can impact long-term health outcomes.

Mismatch in Modern Life

  • In contrast to our ancestors, today's society often promotes sedentary lifestyles characterized by prolonged periods of inactivity. This lack of physical activity can lead to chronic maladaptation, which is detrimental to health due to the mismatch between our evolved biological needs and the realities of current lifestyles, leading to a higher incidence of non-communicable diseases such as obesity, diabetes, and cardiovascular disease.

Assessing Physical Activity Levels

  • Researchers utilize the Physical Activity Ratio (PAR) as a standardized method for measuring physical activity levels. The equation used is:

  • PAR = Total daily energy expenditure (kJ/min) / Basal metabolic rate (kJ/min)

  • Key PAR values are classified as follows:

  • 1.40–1.69: Inactive to lightly active, typical of Western societies with more sedentary work.

  • 1.70–1.99: Moderately active, indicating a balanced lifestyle with regular physical activity incorporated.

  • ≥2.00: Vigorously active, often seen in populations with high physical labor and active leisure pursuits.

Examples of Active Traditional Populations

  1. Hadza People (Tanzania):

  • Average PAR: 1.78 (women), 2.26 (men)

  • Engage in approximately 950 minutes/week of moderate-to-vigorous physical activity (MVPA), significantly exceeding the WHO recommendation of 150 minutes/week for adults.

  1. Tsimané People (Bolivia):

  • Display low cardiovascular disease (CVD) risk factors with an active lifestyle that integrates extensive labor and movement.

  • Average PAR: 2.02–2.15 (men), 1.73–1.85 (women), indicating a highly active engagement in daily life.

  1. Kitava (Papua New Guinea):

  • Estimated PAR: 1.70, reflecting a lifestyle rich in physical activity.

  • Characterized by a low incidence of chronic diseases such as stroke and diabetes, showcasing the health benefits of their active way of life.

Importance of Physical Activity

  • Moderate-to-Vigorous Physical Activity (MVPA) is defined as any activity that yields ≥3 metabolic equivalents.

  • The WHO guidelines recommend:

  • 150 minutes of MVPA each week for adults, as a minimum standard for health.

  • 60 minutes for children and adolescents to complement their growth and development.

  • Engaging in regular exercise is crucial for the prevention and management of cardiovascular diseases (CVD), providing physiological benefits that extend beyond conventional risk factors such as cholesterol and blood pressure levels.

Physiological Benefits of Regular Exercise

  • Cardiovascular Health:

  • Evidence shows that regular physical activity enhances vascular function and structural health, independent of traditional risk factors, contributing to improved arterial elasticity and reduced blood pressure.

  • Exercise induces the release of muscle-derived myokines, which are linked to reducing chronic inflammation and improving cardiac function.

  • These myokines also promote processes like muscle regeneration and combat age-related muscle loss.

  • Muscle and Strength Factors:

  • The decline of muscle strength and mass is significantly correlated with an increased risk of CVD. As such, resistance training is essential for reversing these adverse changes and enhancing overall fitness.

  • Despite its efficacy, resistance training is often underemphasized in health recommendations, particularly for older adults who stand to gain the most benefits in terms of strength and functional capacity.

Exercise and Autonomic Balance

  • Engaging in regular exercise has been shown to improve heart rate variability (HRV), which is a marker of autonomic nervous system function and an important indicator of cardiovascular health. Enhanced vagal tone achieved through exercise contributes to better cardiac function and overall stress resilience.

High-Intensity Interval Training (HIIT)

  • High-Intensity Interval Training is a highly popular exercise modality well-regarded for its time efficiency, requiring less than 20 minutes per session. HIIT induces strong biological adaptations, making it particularly advantageous for cardiovascular health and overall fitness improvements.

Benefits of Different Exercise Modalities

  • Aerobic Exercise:

  • Plays a critical role in improving cardiovascular function and significantly reducing the risk of mortality associated with various health conditions.

  • Resistance Training:

  • Vital for maintaining muscle strength and mass, especially in older adults, who often face a higher risk of CVD and related complications.

Gut Microbiota and Exercise

  • Regular exercise has a profound positive impact on gut microbiota, fostering a diverse and healthy microbiome. This improvement correlates with reduced systemic inflammation, which is linked to better cardiovascular outcomes, highlighting the additional indirect benefits of physical activity on gut health.

Conclusions & Recommendations

  • The evidence overwhelmingly supports that regular physical activity confers a multitude of health benefits that are not solely dependent on traditional cardiovascular disease risk factors.

  • Therefore, exercise prescriptions should emphasize the inclusion of strength training, particularly for aging populations, to promote both cardiovascular and functional health over time.