Rehabilitative Treatment
Rehabilitative approaches used to treat dysphagia seek to restore the function of the subsystems of swallowing resulting in a long-term change to the swallow physiology. Rehabilitative techniques should result in a change in muscle physiology (peripheral changes) and/or neural adaption (central changes). Rehabilitative strategies may be direct, which means that they include swallowing of specific boluses in a controlled condition, or indirect, which means that oral intake is not included as part of the exercise. Ideally, rehabilitative treatment approaches allow for the elimination of compensatory strategies. Over time, with repetition, rehabilitative techniques, which may include strength training, skill training, or training of timing and coordination, should restore aspects of swallow function.
Strength Training
Swallow is a pressure-driven event that is influenced by the strength of the swallow. When weakness occurs, improvements may be achieved through strength training. Before designing and initiating a strength training program to improve swallow function, clinicians must be aware of the principles of strength training to obtain the maximal effect from the rehabilitative program. Aspects of strength training include the type of muscle fiber and muscle configuration being trained, the task being trained, and the training protocol including progressive resistance, intensity, and frequency of the strengthening protocol. Strength training is achieved through structured exercise. General activity is not the same as exercise, although it is certainly better than inactivity. The goal of strength training is long-term improvement of swallow physiology. Thus, strength training should be geared to increase force or pressure, or improve power, timing and/or endurance of muscles involved in swallowing and resulting swallow events.
In this section we will discuss common principles for strength training and their application to oropharyngeal muscles. Strength training should systematically alter and control each of these variables to progress towards a goal.
Muscle Fiber Types
Recall the divisions of muscle fiber types and their force generation profile (Box 4.26). Although muscles may contain multiple fiber types, there tends to be a predominance of a fiber type within a muscle compartment. Grossly, skeletal muscle can be divided into 3 fiber types, commonly referred to as Type I, which are slow twitch, fatigue-resistant fibers, Type IIa, which are fast twitch fibers that are somewhat fatigue-resistant, and Type IIb, which are fast twitch fibers that are highly fatiguable. Muscles composed of a predominance of Type II fibers are better suited for quick forceful movements, whereas muscles with predominately Type I fibers are better suited for low force, high endurance activities. It is assumed that much of swallowing is dependent on the function of Type II fibers.
Box 4.26: Muscle fiber types
Fiber type is not static. With injur