Progressive strength training involves application of the principle of overload.
Overload means providing a greater than normal stress, or load, on the body to stimulate further strength development.
For the human body to get stronger, more fit, and see functional improvements, it must be challenged to perform in ways in which it is not accustomed. There is a saying in strength training: “If nothing changes, nothing changes.” To make improvements in strength and functional ability, there is a need to safely challenge our participants.
This may be daunting as many class participants are managing chronic conditions, are at different fitness levels and abilities or have different experiences with exercise. Variation in strength exercise is the key to safe progression for older adults, especially in a group setting.
Strength training variations for group exercise include:
- Using different resistance tools
- Changing repetitions and speed of movement
- Altering lever length and range of motion
- Changing body position to maximize gravity
Additional training methods, such as focusing on the type of muscle contraction, can cause an overload adaptation, or strength gain. An eccentric muscle contraction is the strength produced when a muscle lengthens under resistance. You are using eccentric strength when you sit down in a chair and your quadricep muscle lengthens. A concentric muscle contraction is the strength produced when a muscle shortens under resistance. An example of this is when you get up from a chair, as your quadriceps are shortening. Isometric strength is strength measured against an immovable object. There is no visible movement of the joint being used. An example of isometric strength is hovering over a chair seat.
Instructor tip: Due to blood pressure response, we recommend performing a modified isometric pulse versus an isometric hold with resistance tools. To perform the modification, complete the exercise with a small range of motion.
A decline in mobility among the aging population is closely linked with changes in the muscle force-velocity relationship, or power. The force generated by a muscle is a function of its velocity, the speed at which an object moves in a particular direction. The functional implications of these changes result in decreased reaction time and slower walking speeds. Providing specific attention to various speeds within different types of muscular contractions benefits activities of daily living as it improves functional power.
Following are examples of rhythmic variations focusing on concentric, eccentric and isometric training:
Lower body example:
- Quickly standing up from your chair in a count of 1 (concentric)
- Slowly sitting down in your chair for a count of 3 or 7 (eccentric)
- Hovering over the seat of the chair for a count of 4 (isometric)
Upper body example:
- Biceps curl: lift on a count of 1 (concentric)
- Lower on a count of 3 or 7 (eccentric)
- Hold in the center, 90 degrees at the elbow, for a small pulse or count of 4 (isometric)
For training to affect muscular strength and function, it must provide a stress level over and above the class participants normal daily activity. As participants improve their muscular strength and endurance, training variations need to be applied to create adaptation, or increased functional capacity. One way to do this is through resistance selection. Knowing how to guide participants to choose an appropriate resistance to create overload is important. This will be discussed in the next lesson.