Exercise as it relates to Disease/The effects of endurance training, and endurance training when combined with resistance training, on individuals with multiple sclerosis

This is a critic of a paper discussing physical activity and how it assists with ADHD. It has been written as part of an assignment for the unit Health, Disease and Exercise at the University of Canberra.

Paper: Kerling A, Keweloh K, Tegtbur U, et al. Effects of a Short Physical Exercise Intervention on Patients with Multiple Sclerosis (MS). Kleinschnitz C, Meuth S, eds. International Journal of Molecular Sciences. 2015;16(7):15761-15775.

What is the background to this research?
Multiple Sclerosis (MS) is a disease of the central nervous system (CNS) and it may affect the brain, spinal cord and/or optic nerve. The cause of MS is unknown however it occurs when a wrongly programmed nerve cell causes inflammation in one or more of these areas and damages the myelin sheath around nerve cells. This produces scars or legions which interfere with nerve transmission. Sclerosis means scarring and multiple refers to the often numerous legions that develop. The symptoms vary greatly between individuals but they depend on which parts of the CNS are affected.

Prevalence
 * Most common chronic disease of the CNS in young Australians
 * An estimated 2.5 million people in the world suffer from MS
 * More prevalent in females
 * approximately 70% of people it affects are female
 * 98% are Caucasian

Possible Symptoms
 * Fatigue
 * Changes in vision
 * Stiffness
 * Weakness
 * Imbalance
 * Sensory/neurological problems (numbness and tingling)
 * Continence problems (bladder/bowel control)
 * Cognitive and other neuropsychological symptoms

Where is the research from?
The study was run by the MS Healthcare Center of the Hannover Medical School. Individuals which met the credentials of the study were sought out by neurologists in the Hannover area or through the MS society newsletter. Individuals were eligible to participate in the study if they had MS, were between the ages of 18-65, and had a maximum value of 6 on the EDSS (Expanded Disability Status Scale) which means they suffer a low to moderate level of the disability. Some individuals were excluded from the study due to factors such as cardiovascular risks, pregnancy or if they had been participating in regular physical activity in the prior 12 months. The available subjects were randomised by age, BMI and EDSS, and placed into one of two testing groups. Although the study began with 60 participants, 18 of these were withdrawn or pulled themselves out of the study due to personal issues. The reasons ranged from a lack of time or difficulty committing to training, to a worsening of symptoms.

What kind of research was this?
This was a randomised, uncontrolled study. There were two testing groups which underwent either endurance training or a combined endurance and resistance training program to show the effects each had on a number of factors for the individual with MS.

What did the research involve?
Initial baseline testing and surveying was conducted on all of the participants in the study. This consisted of:
 * BMI
 * EDSS
 * Modified Fatigue Impact Scale (MFIS)
 * V02 peak
 * Ventilatory anaerobic threshold (VAT)
 * Resting heart rate- Measured by an ECG
 * Heart rate while working at 50W- Measured by an ECG
 * Maximum force production (Fmax) of knee flexion and extension, and shoulder flexion and extension- Measured on a dynamometer
 * Quality of life (QOL) as indicated by a SF-36 questionnaire.

After this testing the participants were randomised and placed into either the endurance workout group (EWG) or the combined workout group (CWG). The EWG consisted of 13 females and 5 males, while the CWG consisted of 15 females and 4 males. The training intervention went for three months and involved two 40 minute sessions per week at a moderate intensity. Both groups start each training session with 20 minutes of work on a bicycle ergometer, the second half of the session is where it differs. The EWG does another 20 minutes on a different machine with the choice of using a cross trainer, stepper, arm ergometer or rowing ergometer. The CWG does 20 minutes of resistance work that was prescribed and supervised by a sports scientist. The participants would complete two sets of 10-15 repetitions on six out of the eight different machines. The eight machines available were leg press, hamstring curl, chest press, row, pull down, overhead press, abdominal, and back extension. When the three months of exercise intervention was completed the tests that were used for baseline measurements were repeated to see any improvements or declines.

What were the basic results?

 * A better endurance capacity after the training period was apparent from a lower heart rate at rest and at 50 W and lower lactate values at 50W in both groups.
 * Motivation-independent parameters, such as VAT, lactate at 50 W, and heart rate at 50 W, showed a significant improvement of aerobic capacity
 * The Fmax for each of the measurements increased, as shown by the dynamometer testing at the end of the three month period.
 * Both the EWG and CWG showed improvement in shoulder flexion
 * The results from the SF-36 survey showed improvements in general health perceptions, vitality, social functioning, role limitations due to physical limitations and general health. These factors lead to a better QOL.
 * For both the patients suffering from fatigue indicated in their baseline testing and for the whole group, a significant improvement in fatigue was found, as determined using MFIS.

How did the researchers interpret the results?
The researchers found that the increases in V02 peak were smaller when compared to other similar studies. They put this down to a lower frequency and duration time of training or a possible lack of motivation in the participants in this study. It is still apparent that aerobic capacity was significantly increased especially when considering the motivation-independent parameters as mentioned previously. The researchers were surprised to find that Fmax in the shoulder had increased in both testing groups. Some of the EWG participants did however use a cross trainer, arm ergometer or rowing ergometer on top of the cycling ergometer and is thought to be the main reason for the increase in Fmax in the upper body. This is supported in a similar study by Petajan et al. who also found an increase in muscular strength in subjects who solely participated in endurance activity. Improvements in subjective measures, such as QOL, can be explained by social or group effects independent of physical exercise.

What conclusions and implications should be taken away from this research?
This study shows that moderate activity, in 40 minute sessions, twice weekly, is sufficient in improving various factors in individuals who suffer from low to moderate levels of MS. Aerobic capacity, maximum force production in the knee and shoulder joints, QOL, and fatigue levels were all improved at the end of this three month exercise intervention. A combined endurance and resistance training program is more effective when measuring these parameters however an endurance program can also show similar progression if the machines that are used involve the upper extremities. There were a few limitations or areas where this study could have improved. A control group may have been beneficial as it would have shown the natural progression of the parameters that were measured, without the benefits of an exercise intervention.