Exercise as it relates to Disease/How can resistance training increase lower limb speed of strength during stair walking for people with diabetic peripheral neuropathy?

This Wikibooks page is a fact sheet and critique of the article "Resistance exercise training increases lower limb speed of strength generation during stair ascent and descent in people with diabetic peripheral neuropathy" by Handsaker JC et al. (2015).

Diabetic peripheral neuropathy
Peripheral neuropathy is nerve damage caused by chronically high blood sugar and diabetes. It leads to numbness, loss of sensation, and sometimes pain in your feet, legs, or hands. It is the most common complication of diabetes. Diabetic peripheral neuropathy (DPN) is a chronic complication of diabetes, affecting up to 50% of older patients. People with DPN are five times more likely to fall with over half this number experiencing at least one fall per year. Falls suffered during stair descension account for 60% of fall-related deaths. During stair walking, DPN patients are slower to develop strength at the ankle and knee on initial step contact, which is harmful as studies have shown a reduced strength in this area increases fall risk and rate.[1]

Where is the research from?
The research was conducted on a group of 43 participants; 9 with DPN, 13 with diabetes but no neuropathy and 21 healthy subjects who were the control group. All participants gave their written informed consent and ethical approval was obtained from the relevant bodies for the study. The aim of the study was to analyse the effects of a 16-week resistance exercise training intervention on the speed and knee strength during stair walking in DPN patients.

What kind of research was this?
The research was controlled quantitative data study undertaken by implementing two clinical tests. Within the intervention itself, it incorporated an element of randomized controlled trial (RCT). The research compared data of DPN patients against other diabetics and against healthy counterparts. Results were recorded pre and post intervention to identify its effect.

What did the research involve?
In preparation for the study, each participant was attached with 57 retro-reflective markers. All participants wore specialist diabetic shoes to ensure appropriate and standardized footwear. Electromyographic electrodes were placed on the skin to measure muscle activations representative of major knee and ankle extensors. The participants ascended and descended an eight-step staircase which had four step-embedded force platforms located in the four middle steps. These force platforms measured the individual's ground reaction force, while a 10-camera motion capture system was used to capture whole-body movements. The participants made at least five recorded ascents and descents each with adequate rest in between. They were supported by a safety harness and had the option to use a light handrail if they felt unable to complete the task naturally.

Participants in the intervention then underwent a weekly, 1 hour exercise session for 16 weeks. During these sessions, participants completed exercises including leg extension, leg press and ankle press. The main aim was to increase speed of muscle response of ankle/knee flexors.

What were the basic results?

 * Stair ascent - After the exercise intervention, ankle and knee speed of strength generation was significantly higher in the 'DPN' (DPN-INT) and 'diabetes but no neuropathy' (D-INT) patient groups (P < 0.01). There was no observed differences in the diabetic control group (D-CON) pre vs. post intervention. Before intervention, speed of strength at the knee for both D-INT and DPN-INT groups were significantly lower than the healthy control (H-CON) group, but post intervention results showed no observed differences. Before intervention, DPN-INT had similar speed of ankle strength to H-CON, but post intervention they became significantly faster. Before intervention, D-INT had significantly slower ankle strength vs. H-CON, but post intervention results demonstrated no differences.
 * Stair descent - After the intervention, speed of ankle and knee strength generation was also significantly higher in both DPN-INT and D-INT (P < 0.01) and D-CON (P < 0.05) groups. Before intervention, speed of knee and ankle strength in D-INT was significantly slower than H-CON, but after intervention there was no observed differences. Before intervention, DPN-INT had similar ankle and knee speed of strength to H-CON but became significantly faster post intervention.

Conclusions from the research
The study demonstrated that resistance exercise training can improve speed of ankle and knee strength during stair walking in diabetic and DPN patients. These improvements are expected to improve stability during the initial weight acceptance phase of stair walking and ultimately aid in reducing fall risk. Reduced speed of strength generation in populations such as the elderly, is attributed to muscle structure alterations and neural changes. Resistance exercise training has been identified to be the most effective method of increasing speed of strength generation via improving neural drive and increasing muscle mass. Following exercise interventions, participants self-reported increased activity levels and ability to perform everyday tasks that were previously beyond their capabilities. These improvements were a result of increased lower limb strength. Therefore, such exercises should be incorporated into exercise programs and interventions as a means of prevention and treatment. There are other studies that state balance training is the most effective training intervention, rather than ones with exclusive strength focus or endurance/strength combination.

Practical advice
The real life implications of this research allow DPN patients to be aware of the most effective forms of treatment. Before undertaking advice such as resistance training programs, patients should be aware if they are in suitable condition. In clinical settings, the use of simple symptom/screening questionnaires are advised. As another way to assess clinical signs, composite scores, e.g. the Neuropathy Disability Score (NDS), are used and provides an indication of disease deficit. Areas of safety concern prior to exercise are open foot ulcers (studies show weight-bearing exercise did not lead to increases in ulcers), requirement to use a walking aid and any history of other disorders that affect gait and visual acuity.[1]

Further information & resources
More information on Diabetic peripheral neuropathy; its signs and symptoms, treatment, management and support groups can be found below
 * General information: http://www.diabeticlivingonline.com/complications/feet/information-about-diabetic-peripheral-neuropathy?page=0%2C1
 * General information: http://www.mayoclinic.org/diseases-conditions/diabetic-neuropathy/basics/definition/con-20033336
 * Exercise guidelines & benefits for patients: http://www.consultant360.com/articles/exercise-patients-diabetic-peripheral-neuropathy-getting-right-foot
 * Diabetes support groups: https://www.diabetesvic.org.au/support-groups