Bladder Health Week, November 16-22, 2008
In honor of Bladder Health Week we are posting information on bladder care during exercise. Today we will focus on those with Multiple Sclerosis and Thursdays focus will be Resistance Training for those with physical disabilites. As posted at: National Center on Physical Activity and Disability 
Best Exercises and Measurement of Aerobic and/or Strength Capacities
TrainingRegarding best exercises, in 1992 Ponichtera et al. measured muscle torque at several speeds for both concentric and eccentric contraction on 9 subjects with multiple sclerosis and 9 healthy controls who generated isokinetic contractions of the quadriceps and hamstrings on an isokinetic dynamometer. They concluded that strengthening programs focusing on concentric exercises at 90 degrees per second may be the preferred strengthening exercise for subjects’ quadriceps and hamstring muscles.
MeasurementIn 1993, the same team examined maximum aerobic capacity in 9 subjects with multiple sclerosis (EDSS 1-4) and 9 control subjects on recumbent leg ergometers on land and in water. They determined that some persons with multiple sclerosis (depending on level of impairment) could attain maximum aerobic capacity without side effects, whereas those with more physical impairments would need more adjustments, such as for leg cycling (Ponichtera et al., 1993).
In 1995, Ponichtera et al. studied the best means of exercise testing and practice for persons with multiple sclerosis. Vo2max was measured in a discontinuous, progressive intensity exercise test on 10 subjects with multiple sclerosis and 10 control subjects generating each of 3 modes of ergometry (leg, arm, and leg/arm) on 3 separate days. The investigators concluded that the combined leg/arm ergometry is preferred because (1) upper extremities need more training and training legs alone is insufficient, and (2) using leg and arm power disburses the exercise load over a larger muscle mass and there is less possibility for “localized” fatigue.
Regarding measurement of strength capacities, Pepin et al. (1998), conducted a study of 14 subjects with multiple sclerosis who performed isometric handgrip contractions at 30% maximal voluntary contractions (MVC) to the point of fatigue. The results showed that it is possible to get consistent reliable responses to this exercise, despite motor dysfunction. (The MVC reliability estimates were 0.98.) The authors, however, did question the replicability of their findings for subjects with higher EDSS levels.
FatigueResearchers studying fatigue during exercise have attempted to isolate and measure fatigue and weakness/strength components, and have questioned to what extent the fatigue is due to intrinsic physiological deficits or deconditioning.
Recently, Schwid et al. (1999) studied the quantitative assessment of motor fatigue and strength in 20 subjects with multiple sclerosis and 20 control subjects. Maximal voluntary isometric strength, motor fatigue, and static fatigue were tested and retested by different exercise and strength tests in 2 distinct sessions, in order to measure test-retest reliability. Results showed that though subjects with multiple sclerosis had more fatigue for sustained contractions, repetitive contractions, and ambulation, motor fatigue was different from weakness since the fatigue was not correlated with weakness from individual muscles. This suggests that strength and motor fatigue can be quantified reliably.
In 1994, Kent-Braun et al. studied a sample of 6 subjects with multiple sclerosis and 8 control subjects to investigate the role of metabolism in muscle fatigue during exercise. They measured the peak force generated from a maximal voluntary isometric contraction during 3 sessions and determined that for mildly impaired persons with multiple sclerosis, muscle fatigue during exercise is not related to metabolic, but to activation failures. It was observed that decreases in force during exercise were because of peripheral, not central mechanisms. In 1995 and 1996, the same team studied electrically-stimulated exercise training for subjects with multiple sclerosis and discovered that the fatigue during exercise is because of muscle intrinsic, not metabolic, properties (Kent-Braun et al., 1996)(Sharma et al., 1995).
As posted at: National Center on Physical Activity and Disability