Strength-based Exercise for Chronic Non-Cancer Back Pain: A Review of Clinical Effectiveness

Chronic primary pain typically refers to pain in one or more parts of the body that recurs or lasts for longer than 12 weeks.1 Up to 20% of Canadians live with chronic pain and two-thirds report that their pain is moderate to severe.2 Chronic primary pain may lead to significant emotional distress, anxiety and depressed mood and may cause functional disability and interfere with daily activities.2 The back is considered one of the most common locations of chronic non-cancer pain.3 Although back pain is often attributed to a diverse group of factors2,3 such as genetics, sex, pregnancy status, environmental factors, and psychological factors, its true etiology is difficult to determine.4 Notwithstanding the complexity of diagnosing chronic back pain, there are several pharmacological and non-pharmacological options that are used to manage the condition. Pharmacological options include opioids, nonsteroidal anti-inflammatory drugs, acetaminophen, muscle relaxants, antiseizure medications, antidepressants, and corticosteroids.3 These medications are known to have mild to severe side effects, and in some cases are accompanied with a significant risk of addiction.5 Alternate management options range from mind-body practices and acupuncture to surgery, physical therapy, and exercise.6 Given that there may be a link between muscle weakness, low physical activity, and increased risk of back pain, strength-based exercise has been extensively explored as a potentially viable treatment option for chronic back pain.7–9 For the purposes of this report, strength-based exercise is defined as exercise that increases muscular strength or toning (i.e., resistance training, intense and low-level weightlifting, body weight exercise designed for strength, and machine repetitions). Specifically, aerobic exercise, yoga, Pilates, tai chi, physiotherapy, and sling training are not included in this definition. A summary of abstracts published by CADTH in 2017 identified 46 systematic reviews (12 with meta-analysis) that evaluated the clinical benefits and harms of exercise for adults with back pain, with publication dates between January 1, 2012 and July 21, 2017.10 The included systematic reviews covered various strengthening exercises, motor control exercises, core-strength training strategies, and resistance training, among other forms of exercise. Strength-based exercise was the intervention of interest in four of the systematic reviews, however, their focus was not exclusively on patients with chronic pain and their comparators were mixed and in some cases, undefined.10 The current review aims to summarize and evaluate evidence regarding the clinical effectiveness of strength-based exercise alone relative to pharmacological interventions alone for chronic non-cancer back pain in non-pregnant people.