March 2021

Strength & Balance Training Improves Function in DPN, But Not HRQoL

The most common neuropathy associated with diabetes mellitus is distal symmetrical polyneuropathy, also known as diabetic peripheral neuropathy (DPN). It affects around 12–50% of individuals with diabetes. DPN is a known important risk factor for serious adverse sequelae such as foot ulceration and amputation. Equally importantly, DPN itself is symptomatically distressing to individuals and is associated with a reduction in health-related quality of life (HRQoL). Previous studies have shown that strength and balance training has improved pain scores in this population. So, researchers from Singapore’s Saw Swee Hock School of Public Health sought to test the effectiveness of a structured strength and balance training intervention in improving HRQoL and functional status in individuals with DPN.

The study compared 2 months of once-weekly home-based strength and balance training (see box) against standard medical therapy. Participants were patients with physician-diagnosed type 2 diabetes and neuropathy recruited from five public sector institutions in Singapore. Participants (143 total) were block-randomized to intervention or control arms (intervention, n = 70; control, n = 73); 67 participants were included in each arm for the final intention-to-treat analysis. Outcomes were assessed at baseline, 2 months and 6 months. Primary outcomes were change in physical component summary (PCS) score of SF-36v2 (a 36-item generic HRQoL validated instrument) and EQ-5D-5L index score (derived from a 5-item generic HRQoL instrument [EQ-5D-5L]) over 6 months. Secondary outcomes were change in functional status (timed up-and-go [TUG], five times sit-to-stand [FTSTS], functional reach, static balance, ankle muscle strength and knee range of motion) and balance confidence over 6 months. Mean differences in scores between groups were compared using mixed models.

Intervention Exercises

  • Range of motion: passive movements to the extent possible of the knee (flexion–extension), ankle (dorsi–plantar flexion), forefoot (inversion–eversion) and toe (flexion–extension, adduction–abduction) joints
  • Muscle strengthening: active movements against resistance (using a theraband) at the knee (flexion–extension), ankle (dorsi–plantar flexion), forefoot (inversion–eversion) and toe (flexion–extension, adduction–abduction) joints
  • Static balance: single leg stance, tandem leg stance, toe and heel stance
  • Dynamic balance: tandem walk, sideways walk, backward walk
  • Endurance: sitting-to-standing mini-hops, brisk walking

All sessions began with a 5 min pre-exercise warm-up of gentle stretches and ended with a 5 min cool-down of slow walking. Exercise intensity was gradually increased based on participant performance.

Results: The current study found no significant difference in overall HRQoL scores (PCS score, EQ-5D-5L index score) between intervention and control arms after 2 months of structured strength and balance training in individuals with DPN. However, significantly greater improvement in the body pain domain of HRQoL was seen in the intervention arm as compared with the control arm. In addition, there were significant improvements in several functional status variables in the intervention arm compared with the control arm. These included statistically significant and clinically meaningful improvements in functional task performance, balance confidence, range of motion at knee, and muscle strength at ankle. These improvements were sustained for up to 4 months after the end of the intervention.

Among the specific domains of HRQoL, body pain was the only domain that showed significant improvement with intervention. It is possible that the improved physical conditioning in these individuals may have reduced the effect of pain on daily life and activities. However, it needs to be noted that the body pain domain is not specific to neuropathic pain and participants may have had pain due to other comorbidities that responded to the intervention.

One important functional measure that improved as a result of the intervention was balance confidence. Low balance confidence has been associated with greater physical difficulties and lower HRQoL. More importantly, low balance confidence has been shown to predict poorer mobility in the future. Balance confidence may determine the nature, duration and intensity of physical activities an individual undertakes on a daily basis and a decline in confidence, either due to a previous fall or the fear of falling, may place an individual on a downward spiral of declining physical functioning and further deteriorating balance confidence. Ours is the first randomized controlled trial to demonstrate the effectiveness of structured physical therapy in improving balance confidence in individuals with DPN.

Short-term structured strength and balance training did not influence HRQoL but produced sustained improvements in functional status and balance confidence at 6 months. More intensive interventions may be needed to influence HRQoL in these individuals. However, this intervention may be a useful treatment option for individuals with DPN to reduce the risk of falls and injuries.

Source: Venkataraman, K., Tai, B.C., Khoo, E.Y.H. et al. Short-term strength and balance training does not improve quality of life but improves functional status in individuals with diabetic peripheral neuropathy: a randomised controlled trial. Diabetologia 62, 2200–2210 (2019). Use is per Creative Commons License CC BY 4.0.

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