Nociception is the process by which nociceptors detect mechanical, thermal, or chemical stimuli that may lead to the perception of pain. The sensory stimulus can be mechanical, thermal, or chemical. Central sensitization is a phenomenon in which the central nervous system (CNS) becomes hypersensitive to sensory input, leading to an exaggerated or persistent pain response.

Pain modulation involves processes through which the body can increase or decrease pain intensity. The 3 types of key pain modulation include:

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  Gate control: Nonpainful stimuli can inhibit the transmission of painful signals at the spinal cord level by closing the gate to nociceptive input. According to this theory, stimulation of large-diameter Aβ fibers, which carry touch, pressure, and vibration, can inhibit the transmission of pain signals carried by smaller Aδ and C fibers. As an example, rubbing or tapping the skin near an area of pain, such as rubbing your elbow after bumping it, can reduce the sensation of pain by activating these inhibitory pathways.

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  Central modulation: Psychological, emotional, and cognitive factors can influence pain perception by altering CNS processing. As such, modulation may amplify or dampen pain signaling.

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  Conditioned Pain Modulation (CPM): The brain inhibits pain through endogenous pain-inhibition systems. Specifically, the brain is able to send serotonergic neuronal projections that inhibit the firing of trigeminal and spinal pain-transmission neurons.

CPM can be demonstrated in athletes. Numerous studies have demonstrated that endurance athletes have greater pain tolerance than the average population. In one study, triathletes exhibited higher pain tolerance ( P <.0001), lower pain ratings ( P <.001), and lower fear of pain values ( P <.05) than the general population.

Chronic pain persists or recurs for longer than 3 months and is estimated to affect 20% of people worldwide. Large population studies indicate that individuals who engage in more physical activity have a reduced risk of developing chronic pain, while a sedentary lifestyle enhances this risk. Chronic pain can affect muscle structure and function, leading to changes in muscle activation patterns, atrophy, and deconditioning. Additionally, low-grade inflammation impairs muscle repair functions.

Muscle tissue is composed of muscle fibers containing myofibrils that run the length of the muscle fiber and are made up of repeating units called sarcomeres. Sarcomeres are made up of actin and myosin, which help generate muscle contractions.

Three primary types of muscle contractions include isometric contractions, isokinetic contractions, and isotonic contractions. They are differentiated by whether and how the muscle changes length during contraction. Isotonic contractions are further subdivided into concentric and eccentric contractions. These contractions are summarized with examples in Table 1 .

In many chronic musculoskeletal conditions, there is no significant difference in outcomes when comparing types of muscle contractions used during exercise. For example, a 2024 randomized controlled trial by Khaledi and colleagues found that in patients with chronic low back pain, both isometric and isotonic exercises led to significant improvements in pain and disability, with no major differences between the 2. Similar results have been observed in studies on chronic shoulder and neck pain, where both contraction types provided meaningful relief. However, in knee osteoarthritis, multiple randomized trials suggest that isokinetic training may offer additional benefits. Compared to isometric and isotonic approaches, isokinetic exercises have been associated with greater improvements in quadriceps strength, pain reduction, and cartilage thickness. Despite these differences, all 3 types of muscle contractions can support pain relief, but isotonic and isokinetic exercises may offer more functional benefits, especially when the goal is to build strength and improve joint control. Isometric exercises remain valuable as a lower-intensity option, particularly for patients in pain or those with limited movement tolerance.

Inflammation or trauma releases endogenous substances that stimulate muscle nociceptors, causing muscle tenderness or hyperalgesia. This can lead to muscle spasms, guarding, atrophy, fatigue, and tightness. Muscle pain can also impact strength as evidenced in electromyography (EMG) studies. For example, it has been demonstrated that during dynamic contractions, muscle pain leads to a marked reduction in EMG activity in muscles that are agonistic to the painful muscle.

Like a 3-legged stool, an effective pain rehabilitation program relies on cardiovascular training, strength training, and flexibility. If one component is missing, the system becomes unbalanced and unable to provide proper support. Cardiovascular training enhances circulation and endurance, strength training protects joints and supports function, and flexibility preserves range of motion and prevents maladaptive movement patterns. Together, these elements create a balanced and sustainable foundation for recovery.

Cardiovascular training improves heart, lung, and circulatory efficiency by strengthening the musculature, enhancing lung gas exchange, and supporting overall vascular function. These exercises are also effective for burning calories which can help with weight loss and body fat reduction. Intensity refers to the amount of energy expended as a function of heart rate. For chronic musculoskeletal pain, low to moderate intensity exercise (50%–60% of max heart rate) has been demonstrated to improve chronic pain symptoms. In chronic low back pain, high intensity cardiovascular training (60%–85% of max heart rate) leads to decreased pain intensity, increased exercise capacity, and reduced disability. ^,, High intensity training also improves circulation, aiding healing and reducing inflammation in areas like the low back. Mental resilience and the ability to cope with chronic pain have also improved.

Muscle flexibility is vital for pain prevention and treatment because it helps restore and maintain a functional range of motion, reducing stiffness and preventing compensatory movement patterns. When muscles are tight, they place additional stress on joints and surrounding structures, often exacerbating pain. Improved flexibility supports posture and alignment, which can relieve mechanical pressure contributing to chronic pain. ^, By incorporating regular stretching and mobility exercises, patients can break the cycle of immobility and pain, promoting long-term recovery and resilience.

However, excessive flexibility, as seen in conditions like Ehlers-Danlos Syndrome (EDS), can lead to joint instability and pain. In hypermobile individuals, the ligaments and tendons that normally stabilize the joints are overly elastic, making it difficult for joints to maintain proper support during movement or rest. This chronic instability can lead to repetitive microtrauma, muscle overcompensation, and early joint degeneration, all of which contribute to persistent pain. Isometric exercises are recommended for EDS patients as they strengthen muscles without putting excessive strain on unstable joints. By engaging muscles in a controlled, static way, these exercises help improve joint stability and reduce the risk of injury or dislocation. ^,

Physical therapy focuses on improving physical function and mobility through targeted interventions. These exercises are designed to enhance strength, range of motion, coordination, and balance, with a goal of helping individuals return to their daily activities. Modalities such as electrical stimulation, massage, cryotherapy, and dry needling may also be beneficial. Physical therapy is tailored to each patient’s needs, limitations, and goals. Education on injury prevention and strategies to minimize pain exacerbations are also central components of treatment.

Research demonstrates that physical therapy is effective for musculoskeletal conditions, chronic pain, and postsurgical recovery. For example, physical therapy in low back pain patients reduces pain intensity, improves physical function, and reduces disability. ^,, Physical therapy has also been shown to be effective for tendinopathies, bursitis, and osteoarthritis. Clinical examples demonstrating the benefits of physical therapy are listed as follows:

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  Eccentric exercises can reduce pain and improve function in Achilles and patellar tendinopathy.

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  Strengthening adjacent muscle groups has been demonstrated to improve pain and range of motion in bursitis. ^,,

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  Physical therapy is effective in reducing pain associated with osteoarthritis, particularly in the knee and hip joints. ^,

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  Postsurgical patients have shown improved quality of life and reduction of persistent pain with physical therapy.

Dance therapy uses expressive and structured movements to promote emotional and physical healing. Therapists demonstrate simple and flowing movements to increase body awareness. The therapist might use music, silence, objects, or themes. Dance demands attention to music, rhythm, and movement, which distracts from pain signals. It also provides a nonverbal outlet for trauma, anxiety, and depression. There is a correlation between strong emotional expression and a decrease in pain intensity when engaging in dance therapy. ^,,

In osteoarthritis, dance-based interventions have been shown to significantly reduce pain and improve physical function and quality of life. Dance emphasizes flexibility and core strength which supports better posture and alignment, reducing wear and tear on the joints. Additionally, dance therapy shows promise for neuropathic pain by increasing pain thresholds and activating pain-modulating brain regions such as the dorsolateral prefrontal cortex.

Aquatic therapy, or hydrotherapy, involves performing exercises in the water. The buoyancy of water supports the body and reduces joint stress, allowing for pain-free movement, which is particularly beneficial for individuals with chronic pain conditions. Additionally, the resistance of water provides a natural form of strength training, engaging muscles without the need for weights. The hydrostatic pressure exerted by the water helps reduce swelling and improve circulation, aiding pain relief and muscle relaxation. Aquatic exercises also provide low-impact aerobic conditioning.

Aquatic therapy has proven to be effective for osteoarthritis as it reduces pain and improves joint function and mobility, particularly in knee and hip osteoarthritis. ^, Hydrotherapy reduces spinal load through buoyancy, making it an ideal exercise for patients with back pain.

Walking is a low-impact, widely accessible exercise that offers substantial benefits for chronic pain management. Engaging in regular walking can improve cardiovascular function. It also aids in building muscle, particularly in the lower body, which supports joint stability and reduces injury risk. Walking also moves joints through their natural range of motion, functioning as a form of dynamic stretching.

In postoperative patients, walking and early mobilization lead to faster recovery and shorter hospital stays. ^, Walking improves spinal mobility, strengthens supporting muscles, and encourages overall physical activity, making it an ideal form of exercise for individuals with chronic low back pain. It also strengthens the muscles surrounding the knees and hips, helping to relieve pressure on these joints, which is an essential factor in managing hip and knee osteoarthritis.

Cycling strengthens the lower body muscles, particularly the quadriceps, hamstrings, glutes, and calves. This helps stabilize joints and reduce overall pain. The repetitive pedaling motion promotes flexibility in the hips and knees, which can help prevent stiffness. Additionally, cycling improves cardiovascular fitness and circulation, which are crucial for pain management and tissue healing. It can be done on either stationary or outdoor bikes, offering a safe and adaptable form of exercise.

Cycling has been shown to be helpful in neuropathic pain, which is often linked to ischemia-related nerve damage. Similar to walking, cycling also improves lower extremity strength and reduces pain from knee and hip osteoarthritis. However, improper bike setup and a stooped posture can exacerbate symptoms of back pain. Adjusting seat height and handlebar position to maintain a neutral spine can prevent lower back strain.