Home-based Resistance Training for Adults With Severe Obesity

This study evaluates whether adding home-based resistance training to a multidisciplinary specialist weight management service can promote weight loss and improve physical function, strength, power and quality of life in adults with severe obesity. The study also investigated whether performing resistance exercises as fast as possible can yield further improvements in physical function compared with traditional slow-speed resistance training.

All recruited participants completed a 3-month home-based resistance training programme with behavioural support; half of the participants performed resistance exercises in a slow and controlled manner, whereas the other half performed resistance exercises with maximal intentional velocity.

Severe obesity reduces muscle contractile function, which manifests as a diminished ability to perform activities of daily living. These functional impairments often lead to pain during movement and a decreased motivation to exercise.

In the United Kingdom (UK), specialist Tier 3 weight management services are provisioned for adults with severe obesity. Tier 3 services comprise a multidisciplinary team (MDT) of specialists and mainly adopt an educational approach, focusing on psychological therapy, dietary modification, pharmacotherapy and physical activity advice. However, current Tier 3 programmes do not specifically address the functional impairments imposed by obesity, which predisposes adults with severe obesity to musculoskeletal pain and pathology.

Adding supervised resistance training to MDT weight management programmes has been shown to improve functional capacity in adults with severe obesity. However, supervised interventions place considerable time and resource burdens on the service provider and patient, which may not be conducive to sustained participation. Obese individuals often report feeling too embarrassed to exercise in front of others and feel uncomfortable appearing in public wearing exercise clothing. Home-based exercise is a convenient alternative to supervised interventions and may promote similar functional adaptations.

Traditional resistance training typically involves sustained contractions at low to moderate velocities. While this method of training is effective for augmenting maximal strength production, which is executed at slow velocities, it may neglect the development of muscle power. This is problematic because lower-limb power has recently emerged as a critical determinant of function in adults with severe obesity.

Power training integrates a high-speed component into conventional resistance training exercises. Research in older adults has consistently shown that power training is superior to conventional slow-speed strength training for improving functionality. Preliminary evidence also exists supporting the superiority of power training in sarcopenic obese adults. Nevertheless, it is unknown whether home-based power training is feasible or effective when added to an MDT weight management programme.

The investigators recruited participants from a UK Tier 3 specialist weight management service. In a prospective, parallel groups, randomised design, participants were randomly allocated to a slow-speed strength training group or a high-speed power training group. Both groups completed a 12-week, individualised, home-based resistance training intervention (2x/week) with behavioural support. The high-speed power training group performed resistance exercises with maximal intended concentric velocity whereas the slow-speed strength training group maintained a slow (2-s) lifting speed. Outcomes were assessed at baseline, 3-month (post-intervention), and 6-month (follow-up) endpoints.

Eligibility Criteria:
Inclusion Criteria:

* Currently enrolled in a Tier 3 specialist weight management service in the United Kingdom
* Body mass index of ≥ 40 kg/m2 or between 35 and 40 kg/m2 with a serious co-morbidity (such as type 2 diabetes or obstructive sleep apnoea).
* Aged ≥ 18 years
* Willing and able to give written informed consent.
* Understand written and verbal instructions in English

Exclusion Criteria:

* Unstable chronic disease state
* Prior myocardial infarction or heart failure
* Poorly controlled hypertension (≥ 180/110 mmHg)
* Uncontrolled supraventricular tachycardia (≥ 100 bpm)
* Absolute contraindications to exercise testing and training as defined by the American College of Sports Medicine
* Current participation in a structured exercise regime (≥ 2x/week for the last 3 months)
* Body mass ≥ 200 kg
* Any pre-existing musculoskeletal or neurological condition that could affect their ability to complete the training and testing