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Title: Diabetic peripheral neuropathy : primary pathologies and the role of physical activity as a treatment intervention : a preliminary study
Author: Meana-Esteban, Alejandro
ISNI:       0000 0004 2732 7302
Awarding Body: Cardiff University
Current Institution: Cardiff University
Date of Award: 2011
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Diabetic peripheral neuropathy (DN) is the most common complication in diabetes mellitus affecting up to 50% of this population. Foot ulceration in DN is a major health problem, often leading to lower-limb amputations and increased mortality rates. A combination of gait and microcirculatory alterations increases the risk of foot ulcerations in DN subjects. DN is also linked to an increased risk of cardiovascular diseases and poor quality of life (QOL). Physical activity (PA) plays an important role in the prevention and treatment of diabetes mellitus. Thus, PA has been associated with positive changes in glucose control, obesity and blood pressure. However, almost all the studies investigating PA interventions in subjects with diabetes mellitus have been carried out in individuals without neuropathic complications, whereas the effect of PA programmes in DN subjects is still unknown. In addition to that, the vast majority of studies have investigated the association between PA and health problems commonly linked to type 2 diabetes whereas the relationship between PA and additional problems associated with DN (i.e. risk of foot ulceration, sensory neuropathy or QOL) have received minimal attention. Therefore, the principal aim of this study was twofold: 1) to quantify differences between DN and healthy individuals in the primary pathologies that may co-exist in DN, with special attention to gait and microcirculation due to their association with foot problems; and 2) to evaluate the overall effect of a PA intervention, based on strengthening and foot mobility exercises, in modifying the primary pathologies linked to DN. Prior to the main study, a number of reliability studies were carried out to determine the reliability of some the methods used in the main part of the study. Preliminary studies Three reliability studies were carried in the present investigation. One study investigated the reliability (within- between-day) of near infrared spectroscopy to quantify muscular blood flow and oxygen consumption in the lower limb using a venous occlusion method (microcirculation). The other two studies investigated the reliability (within-day) of two different approaches to calculate the time differences between electromyography data and mechanical output (force) (electromechanical delay) during different conditions. Substantial reliability (ICC>0.6) or higher was found in all the three studies. Electromechanical delay values for the distal leg muscles were significantly higher in DN subjects compared to healthy individuals. Main study The main study was composed of two parts. Part 1 (cross-sectional study) investigated group differences between subjects with DN (N=53) and healthy individuals (N=25) whereas part 2 (intervention study) investigated group differences over time between two groups of subjects with DN; one participating in a 16 week PA programme (N=21) and the other as controls (N=20). Both studies followed the same experimental protocol and investigated the same domains (general health, gait, microcirculation and QOL). IV Cross-sectional study This study confirmed that DN is a complex condition that affects all the domains measured in the present investigation. Thus, the DN group showed significant differences (p<0.05) in: 1) traditional cardiovascular risk factors (blood pressure); 2) gait (spatial-temporal characteristics, forefoot foot pressures and muscular activity patterns); 3) microcirculation (blood flow and oxygen consumption in response to exercise stress); and 4) QOL compared to the healthy group. Interestingly, the present investigation showed that EMG alterations in DN may be associated with changes in plantar foot pressures and consequently with higher risk of foot complications. Furthermore, results from the present study showed for the first time impairments in exercise-induced microcirculatory responses in subjects with DN compared to healthy individuals. These alterations in the microcirculation were observed both in the muscular vasodilatory capacity as well as in the ability of the muscle to consume oxygen. Intervention study This study demonstrated for the first time that 16 weeks of a PA programme based on strengthening and foot mobility exercises can influence a number of aspects of health that are altered in DN subjects. The most remarkable finding was that the exercise programme improved sensory neuropathy (p=0.027) whilst 16 weeks of strength training did not produce significant changes in strength levels (p>0.115 at least) in the DN subjects. In addition to this results from the present investigation showed that a well controlled strengthening training program does have beneficial effects (p<0.05) on the microcirculation, obesity, blood pressure as well as on mental health QOL. On the other hand, the exercise program did not seem to have a substantial effect on any aspect of gait and HbA1c. Importantly, no adverse effects related to the intervention were reported in any of the volunteers who participated in the physical activity program. Conclusions The present study demonstrated that DN is a condition that affects different aspects of health, of which some are modifiable by a well controlled PA programme (i.e. QOL, blood pressure and weight loss). Furthermore, the intervention seemed to trigger positive adaptations in the microcirculation, in particular in the ability of the muscle to recover from a stress condition (exercise stress). However, the most striking finding was that the intervention improved sensory neuropathy in individuals with DN. Surprisingly, changes in sensory neuropathy did not coincide with changes in muscular strength. This suggests that the lack of muscular adaptation to a PA programme may be caused by intrinsic changes in the muscle and not necessarily to lack of efferent muscle stimulation. In summary, results from the present investigation highlighted 1) the importance of PA as a therapeutic tool in subjects with DN to modify outcome measures associated with type 2 diabetes as well as sensory neuropathy; 2) the need to investigate the effect of PA on DN subjects to challenge the assumption that similar adaptations may occur in DN compared to individuals with type 2 diabetes and no neuropathic complications.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: RC Internal medicine