Final answer:
In the FITT principle, the intensity for vigorous physical activity is when you cannot say more than a few words without pausing for breath, aimed at gaining various cardiovascular and muscular health benefits.
Step-by-step explanation:
In the FITT principle, the intensity for vigorous physical activity should be high enough that you cannot say more than a few words without pausing for a breath. This aligns with recommendations that adults engage in at least 75 minutes (1 hour and 15 minutes) to 150 minutes (2 hours and 30 minutes) of vigorous-intensity aerobic physical activity per week. Intensity is a crucial element of the FITT (Frequency, Intensity, Time, and Type) principle, which is used to guide the development of individual fitness programs.
The concept of intensity within the context of the FITT principle and the 2018 Physical Activity Guidelines for Americans highlights the importance of engaging in exercise that pushes the body sufficiently to achieve cardiovascular and other health benefits. Vigorous activities dramatically increase your heart rate and breathing, ensuring that your cardiovascular system is working at a high level. This intensity translates into activities such as running, high-impact aerobic dancing, swimming laps, or playing sports such as basketball or soccer.
Moderate-intensity activities are also beneficial and are defined as those when you "can talk, but not sing, during the activity." Contrastingly, vigorous-intensity activities demand more effort, and you would struggle to maintain a conversation due to the need for increased oxygen uptake and energy expenditure.
The guidelines emphasize that adults should also engage in muscle-strengthening activities of at least moderate intensity that involve all major muscle groups on two or more days per week. By including vigorous aerobic activities, individuals can experience additional health benefits such as improved cardiovascular and muscular fitness, increased bone density, better cognitive function, and assistance in maintaining a healthy weight.
Physical activity, especially at vigorous levels, can lead to improvements in various aspects of health and has been associated with a reduced risk of chronic illnesses including heart disease, type 2 diabetes, and certain cancers. Individuals who are new to vigorous activities should gradually increase their intensity level to allow their bodies to adapt, and should consult with healthcare professionals if they have pre-existing health conditions or concerns.