Physical activity, cardiorespiratory fitness and cardiovascular health.

Physical training, a subcategory of physical activity (PA), is defined as any structured exercise regimen for the purpose of improving or maintaining cardiorespiratory fitness (CRF), strength, health, functional independence, athletic performance, or a combination of these goals. Aerobic capacity or CRF is typically expressed in mL O2/kg/min or metabolic equivalents (METs; 1 MET = 3.5 mL/kg/min) and can be determined by direct or indirect testing.

Scientific evidence demonstrates that regular physical activity, structured physical training, and higher CRF levels prevent the development of cardiovascular (CV) atherosclerosis and cardiovascular disease (CVD), reducing the incidence of coronary heart disease (CHD)-associated events. Meeting current physical activity guidelines is associated with a lower likelihood of hospitalization, intensive care unit admission, and death among patients with CHD (COVID-19). Higher levels of CRF also appear to confer more favorable outcomes in cases of COVID-19. Overall, current data suggest that failure to meet current physical activity recommendations may have health effects as detrimental as those of smoking and obesity.

In this context, digitization presents itself as an essential tool to maximize the benefits of physical activity and rehabilitation. Innovative platforms allow users to track their progress, adjust their exercise routines and optimize their health in an effective and personalized way.

Mitochondria, known as the powerhouse of the myocyte, are strategically located within the subsarcolemmal reticulum and inner myofibrillar spaces, meeting the energy needs of myocytes as long as oxygen supply is adequate and sustained. Maintaining mitochondrial function is essential to reduce age-related sarcopenia and deterioration of muscle function. CVD is associated with impaired mitochondrial function. Chronic aerobic exercise is now recognized as a viable and durable strategy to preserve mitochondrial health and functionality, which correlates with improved muscle bioenergetics and long-term cardiovascular health.

The mitochondria of muscle tissues (skeletal, cardiac, smooth) form a highly organized reticulum, providing the capacity to meet the changing and acute energy demands of the respective myocytes. As they age, mitochondria can accumulate lesions and changes in their DNA. Mitochondrial function is maintained by a balance between biogenesis (formation of new mitochondria), fusion, fission and mitophagy. Under ideal conditions, these processes balance to maintain a functional mitochondrial pool with proper homeostasis between energy consumption and production. Impaired mitochondrial turnover and mitophagy are associated with atherosclerosis, cardiomyopathy, cardiac hypertrophy and reperfusion injury, possibly due to alterations in ATP production and increased production of reactive oxygen species (ROS).

Aging and physical inactivity alter the balance of the mitochondrial pool toward fission and mitophagy, resulting in sarcopenia and reduced tissue responsiveness to energy demands. However, the following observations about regular exercise are clinically relevant:

• It increases the number of mitochondria in myocytes and improves electron transport and oxidative phosphorylation.

• It is associated with lower ROS production and thus lower levels of oxidative stress.

• It increases mitophagy, which correlates with increased mitochondrial biogenesis and improved muscle performance.

Exercise not only helps maintain functional motor strength and muscle mass, but at the cellular level it also helps myocytes maintain ATP biosynthesis capacity and ensure that their mitochondrial reserve is optimally functional. Healthier mitochondria may also be less predisposed to increase oxidative tone and trigger myocyte apoptosis. In one study, patients with coronary artery disease who participated in an exercise program for 8 months showed a 137% increase in total antioxidant capacity. Continued exercise throughout life attenuates the loss of mitochondrial function and health as patients age. In addition, regular exercise helps control body weight and body fat, prevents the onset of metabolic syndrome, and maintains skeletal muscle insulin sensitivity, among other cardioprotective benefits.

The 2020 World Health Organization (WHO) Guidelines provide recommendations on the amount (frequency, intensity, duration) and types (aerobic, strength, balance) of physical activity that provide significant health benefits. Adults are recommended to engage in at least 150 to 300 minutes of moderate-intensity aerobic physical activity (PA), or 75 to 150 minutes of vigorous-intensity aerobic PA, or an equivalent combination during the week. This recommendation now includes a range (150 to 300 min/week) rather than a volume minimum (≥150 min/week), recognizing that higher volumes of PA produce greater health benefits. Adults can increase their PA levels beyond what is recommended (up to 300 min/week of moderate-intensity PA or up to 150 min/week of vigorous-intensity PA) for additional health benefits. Another important change is the elimination of the requirement to perform PA in intervals of at least 10 min, as the importance of cumulative bouts of PA of short duration (1-2 min) has been demonstrated.

In addition to aerobic activities, adults are advised to perform moderate- to high-intensity muscle-strengthening exercises involving all major muscle groups on at least 2 days per week. Older adults (>65 years) should incorporate multicomponent PA that emphasizes functional balance and strength at moderate to high intensity on at least 3 days/week to improve functional capacity and prevent falls. Previously, strength training and PA was only applied to older adults with poor mobility, but it is now applied to all older adults, regardless of their functional abilities.

A new aspect of the guidelines is the recommendation to limit sedentary behavior, as more sedentary time is associated with lower CRF, poorer cardiometabolic health, increased risk of developing CVD, type 2 diabetes mellitus (DM), cancer, and increased risk of mortality (all-cause, CV, and cancer). Sedentary time should be reduced in all age groups, as replacing it with physical activity is associated with better health outcomes.

There is a dose-response relationship between sedentary time and health indicators such as all-cause mortality, CVD mortality, and CVD incidents. Individuals reporting objectively measured sedentary time greater than 9.5 h/day have a significantly higher risk of mortality compared to those with 7.5 h/day. Replacing 30-60 min/day of sedentary time with any type of PA is associated with risk reductions in several health markers, with estimates for MVPA being more significant compared to low-intensity activities.

People with a physically active lifestyle have a lower risk of developing and progressing many chronic diseases, including CVD, several types of cancer, metabolic diseases, musculoskeletal disorders, neurological diseases, psychiatric conditions, and pulmonary diseases. Therefore, physical activity and structured exercise can be potent health-enhancing drugs. The relationship between PA volumes and cardiovascular disease risk is curvilinear. The greatest risk reductions are obtained by changing from a sedentary to a mildly or moderately active lifestyle.

In this context, the digitization of physical therapy offers a powerful tool to maximize the benefits of physical activity and rehabilitation. Innovative digital platforms allow users to track their progress, adjust their exercise routines and optimize their health in an effective and personalized way.

Digitalization is transforming the way we approach physical rehabilitation. This innovative approach not only offers personalization in treatment and continuous monitoring of patient progress, but also improves patient accessibility and participation in their recovery. The adoption of digital technologies by hospitals, clinics and rehabilitation centers is marking a shift towards a patient-centered approach.

The integration of digital technologies in physical therapy presents a number of significant benefits:

• Hybrid treatments: The combination of face-to-face and digital sessions allows patients to receive care at home, decongesting rehabilitation services and improving the quality of service.

• Remote access: Digital platforms offer the ability to access physical therapy services completely online, from initial assessment to full rehabilitation, ensuring personalized and efficient care.

• Monitoring and digital triage: Remote monitoring of treatments and the implementation of digital triages allow adjusting actions based on the patient’s needs, improving the experience and optimizing available resources.

• Personalized exercise routines: Personalized exercise routines that can be performed from home help promote a healthy and active lifestyle, reducing sedentary lifestyles and improving overall fitness.

Digitalization in physical therapy not only improves the efficiency and accessibility of treatment, but also opens new doors for more effective rehabilitation tailored to the individual needs of each patient. This innovative approach is taking rehabilitation to a new level, all from the comfort and safety of the patient’s home, leading the way to a future of more integrated, patient-centered care.

For more information on the relationship between physical activity, cardiorespiratory fitness and cardiovascular health, see Dr. Lopez Chicharro’s article here.