Effects of Inspiratory Muscle Training (IMT) on Balance Ability and Quality of Life of Diabetes Mellitus Patients

The disease burden of Diabetes Mellitus (DM) is growing rapidly, and multiple complications have been reported including cardiopulmonary and high fall risk which declines the overall quality of life. IMT can be useful technique to improve the physical and functional performance, reduce the severity of complications and enable the individuals to become active members of community. The current study is intended to evaluate the dual effects of IMT on postural stability and pulmonary function of diabetic patients.

Diabetes Mellitus (DM) is a chronic metabolic disease characterized by hyperglycemia due to either deficiency of insulin or the inability of the body to utilize it. Hyperglycemia ultimately leads to multiple organ damage in patients with uncontrolled diabetes. The incidence occurs mostly at the age of 55 years equally affecting both genders. The prevalence of diabetes has been increased four times in the last three decades worldwide and global prevalence is increasing alarmingly with about 1 out of every 11 individuals having diabetes mellitus with 90% patients having type 2 diabetes mellitus. The statistical data depicts a huge burden of disease both in morbidity and mortality globally and an anticipated threat on health care system in future. (1) The complications of diabetes have been reported higher in the South Asia region as compared to western counterparts. In Pakistan, according to National Diabetes Survey of Pakistan (NDSP 2016 - 2017), the pooled prevalence of diabetes was projected to be 26.3% affecting 27.4 million people above 20 years of age. These high numbers are directly and indirectly linked with the economic burden on society and ultimately affect the quality of life of diabetics, families, and community.

Clinically, there are different complications (micro \& macro vascular) associated with DM and these are main sources of morbidity and mortality. Neuropathy, nephropathy, and retinopathy are the microvascular complications whereas macrovascular complications include cardiovascular diseases, stroke as well as other vascular diseases. Apart from these complications, there are few other complications including decreased resistance to infections, dental issues, birth complications in gestational diabetes, poor balance, sarcopenia and increased risk of fall and fractures. The reduced strength and endurance of diaphragm the vital muscle of respiration lead to compromised respiratory functions.

Peripheral neuropathy, retinopathy and vestibular impairments alter the biomechanical stability and strength of postural control in individuals with DM. The instability generates disparity among muscular and neural structures to execute locomotion abilities, so abnormal gait pattern, weakness in lower limb musculature, impair sensory function, diminished reflexes and high fall risk have been observed.

These musculoskeletal complications compromise the mobility level and impede the performance of functional tasks and Activities of Daily Life (ADLs) in patients with DM. The limited movements and participation restrictions in social activities create inaccessibility and dependence on caregiver has been increased. The overall activity level has been declined and decreases the quality of life of individuals and ultimately developing social and economic burden on community.

Management of DM always emphases to improve the current health status and prevent further complications due to uncontrolled DM. Multiple management approaches have been reported in the literature to maintain adequate glycemic control and manage diabetes related complications and co morbidities. Treatment strategies also focus to maximize the quality of life and minimize the risk of treatment related complications including hypoglycemia. Balance and postural impairments are common in DM due to neuropathic changes and there are different training strategies have been documented in literature to improve postural stability and reduce fall risk. The training approaches include Tai Chi, Wii Fit based training, circuit training, strengthening exercises of lower limbs, gait training and task oriented dynamic training to enhance the overall balance abilities.

The central trunk stability and core strength are integral part of postural stability and balance but there is limited evidence to address these for balance training in DM. There is lacking evidence in literature on specific training targeting the central trunk and core strength to improve the balance ability, reduces fall risk and improve quality of life in DM patients.

Inspiratory Muscle Training (IMT) is a device-based training and widely used therapeutic technique for improving inspiratory muscle strength and endurance, thoracic mobility, exercise capacity, reducing dyspnea and increasing quality of life. Recently, IMT has been used to improve balance and physical performance among elderly.

How IMT is a useful intervention to improve cardiopulmonary function, postural control and quality of life? The underlying mechanism of IMT principal and clinical implications has three-fold mechanisms:

First: Diaphragm thickness and strength enhances balance in two ways. Firstly, there is activation of diaphragm during upper limb movements indicating that the co-activation of diaphragm assists in the mechanical stabilization of the spine. Secondly, it plays a major role in the generation of intra-abdominal pressure which helps in the stabilization of lumbar spine during movements like shoulder abduction and adduction i.e., balance perturbations. These changes will improve the lower limb mobility, quadriceps strength, functional performance, postural control response and exercise tolerance among individuals. It creates an overall impact on enhanced balance strategies, physical performance and postural stability in elderly and other pathological conditions including chronic obstructive pulmonary disease (COPD), cystic fibrosis and stroke.

Second: Increases in diaphragmatic mobility and hypertrophy as well as improved neural control and thickness of respiratory muscles including transversus abdominus and internal obliques leads to increase in exercise capacity, pulmonary function and decreased perceived breathlessness and exertion in the patients. It will increase the strength of respiratory muscles ultimately proving it to be an effective treatment strategy in COPD, chronic heart failure, multiple sclerosis and various respiratory diseases.

Third: IMT exerts certain ergogenic effects through increasing diaphragmatic mobility and strength thereby improving the recovery time in sprinters, limiting cardiac sympathetic hyperactivity in cyclists and enhance rowing performance.

Therefore, it can be hypothesized that IMT is not only effective for improving cardiopulmonary function but is also strongly linked with postural stability. The disease burden of DM is growing rapidly, and multiple complications have been reported including cardiopulmonary and high fall risk which declines the overall quality of life. IMT can be useful technique to improve the physical and functional performance, reduce the severity of complications and enable the individuals to become active members of community. The current study is intended to evaluate the dual effects of IMT on postural stability and pulmonary function of diabetic patients.

Eligibility Criteria:
Inclusion Criteria:

* Mini Mental State Examination (MMSE) score \>24
* Type II diabetes: Post 5-8 years diagnosis
* Berg Balance score (30-40)
* Presence of polyneuropathy confirmed through Modified Toronto Clinical Scoring System.

Exclusion Criteria:

* Patients on oxygen therapy
* Uncontrolled diabetes (Confirmed through HbA1C) or disease exacerbation in last 3 months.
* Patients practicing regular physical activity, any balance training in the last 6 months and previous or current experience with IMT
* Patients with musculoskeletal comorbidities that may impair exercise performance
* Peripheral oxygen saturation (SpO2) \< 90% during the Six-Minute Walk Test (6MWT)
* Patients with long COVID syndrome
* Hypertensive subjects without control medication as well as those presenting with a hypertensive peak (\> 140/90 mmHg) for more than 3 consecutive days
* Patients with cardiorespiratory diseases or patients taking drugs that effect balance e.g., beta blockers, anti-anxiety and anti-depressant drugs.