Cardiorespiratory fitness, muscular strength, muscular endurance, body composition and flexibility. These fundamental components of training are what we focus on at The Science of Fitness.
Cardiovascular or Cardiorespiratory fitness (Cardio) refers to your ability to perform repetitive muscular exertion for long periods of time. Muscular endurance seems similar to cardio, but when we discuss muscular endurance we are referring to a muscles ability to hold tension for long periods of time. Muscular strength refers to a muscle's ability to exert force. Body composition can refer to muscle or fat. Basically, we are referring to a change in structure. Flexibility, which becomes increasingly more important as we age, refers to full range of motion of a particular muscle or joint.