Final answer:
Intensity is the term that refers to how hard a person works out.
Step-by-step explanation:
The term that refers to how hard a person works out is intensity.
Intensity measures the level of effort or exertion during physical activity. It looks at factors such as heart rate, breathing rate, and perceived effort. A higher intensity workout usually leads to more calories burned and greater fitness gains.
For example, jogging at a faster pace or lifting heavier weights would be higher intensity than walking or using lighter weights. It's important to find the right intensity for your fitness level and goals to avoid injury and see progress.
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