Acute Pain: A Complete Guide to Understanding and Relief

Acute pain affects millions of Quebecers every year. An ankle sprain, a strained back, a sports injury, or post-operative pain. This sudden and intense pain can be alarming. However, it's often a sign that your body is functioning exactly as it should. Acute pain plays an essential protective role. It warns you that there's a problem and encourages you to take care of the injured area. This guide helps you understand what acute pain truly is, why it exists, how it differs from chronic pain, and most importantly, how to manage it effectively to promote optimal healing. Physiotherapy is the recommended first-line intervention for treating most acute pains. To understand how this discipline can help you, consult our complete guide on physiotherapy and its therapeutic approaches.

What is acute pain and how long does it normally last?

Acute pain is pain that has recently appeared and is likely to be of limited duration. According to the International Association for the Study of Pain (IASP), it generally lasts from a few seconds to a maximum of three months. It usually has an identifiable temporal and causal relationship with an injury or illness.¹

Think of acute pain as a very effective alarm system. When you place your hand on a hot surface, the pain makes you withdraw your hand immediately, even before you have time to think about it. This quick reaction protects you from severe burns.

The term "acute" doesn't necessarily mean "severe." Pain can be acute (recent) while still being mild. Conversely, chronic pain can sometimes be very intense. The main difference lies in duration, not intensity.

Healthcare professionals classify pain based on specific timeframes.²

Most acute pain naturally improves as your tissues heal. This is excellent news worth highlighting. Your body has a remarkable ability to repair itself.

Why does acute pain exist, and what is its biological role?

Acute pain serves a vital protective function. Without it, you wouldn't survive long. People born with congenital insensitivity to pain accumulate severe injuries throughout their lives because they never receive the alarm signal.³

Your pain system works thanks to specialized receptors called nociceptors (danger sensors). These receptors are found throughout your body. They detect potentially harmful stimuli: extreme temperatures, excessive pressure, noxious chemicals, tissue inflammation.

When these receptors detect a threat, they send an electrical signal to your spinal cord, and then to your brain. In a fraction of a second, your brain interprets this signal and decides to produce a sensation of pain to protect you.⁴

Acute pain protects you in several ways. It makes you quickly withdraw the threatened body part. It prompts you to protect an injured area by avoiding certain movements. It motivates you to seek care if necessary. It promotes healing by encouraging you to rest the affected region.

A crucial point to understand is that pain intensity doesn't always match the severity of the injury. A small cut on your finger can hurt a lot because finger skin contains many sensory receptors. A more severe injury in a less innervated area can paradoxically cause less pain. This is known as the principle "pain does not equal damage."⁵

This information is liberating. If you're in a lot of pain, it doesn't automatically mean something serious has happened. Pain signals that there's something to monitor, not necessarily a catastrophe.

How does acute pain differ from chronic pain?

The difference between acute and chronic pain goes far beyond a simple matter of duration. These two types of pain involve different neurological mechanisms and require distinct treatment approaches.⁶

Acute pain represents an alarm system that is functioning correctly. It warns you of a real or potential problem. It normally decreases as healing progresses. It responds predictably to conventional treatments like rest, ice, or anti-inflammatories.

Chronic pain, however, can persist even after tissues have healed. The nervous system itself has changed, a phenomenon called sensitization (when your nerves become overly sensitive). It's as if the volume of your alarm system got stuck in the high position.⁷ To learn more about this topic, consult our complete guide to chronic pain.

Acute pain is expected and normal after an injury. It's part of the healing process. Chronic pain, however, requires a different approach that considers biological, psychological, and social factors. To understand the differences in detail, consult our article on acute vs. chronic pain.

What are the most common causes of acute pain?

Acute pain can have many origins. Understanding the cause helps you choose the right treatment and have realistic expectations about healing time.

Traumatic injuries

Traumatic injuries are the most obvious cause of acute pain. They occur during a specific event that you can identify. To learn more about this topic, consult our guide on ligament pain and sprains.

Sprains affect ligaments. They happen when a joint is forced beyond its normal range of motion. Ankle sprains are the most common, with nearly 25,000 cases per day in North America.⁸

Strains and pulled muscles affect muscles and tendons. They occur during intense effort or a sudden movement. The calf, hamstring, and back are common sites.

Fractures involve a broken bone. The pain is generally immediate and intense. A cracking sound may sometimes be heard at the time of the injury.

Dislocations occur when a bone comes out of its joint. The shoulder and finger are the most commonly affected areas.

Post-operative pain

Any surgery causes acute pain. This is a normal response to tissues that have been cut and manipulated. Proper management of this pain in the first few days after surgery is important to avoid complications.⁹

The level of pain varies depending on the type of surgery. A knee arthroscopy generally causes less pain than a total hip replacement. Your surgeon will give you an idea of what to expect.

Acute inflammations

Inflammation is your body's natural response to an injury. It causes pain, redness, heat, and swelling. These signs indicate that your immune system is working to repair the damage.

Bursitis is the inflammation of a bursa (a small fluid-filled sac that cushions joints). It often occurs in the shoulder, elbow, hip, or knee after repetitive movement or prolonged pressure.¹⁰

Tendinitis is the inflammation of a tendon. It develops gradually with overuse. The Achilles tendon, epicondyle (tennis elbow), and rotator cuff are common sites.

Gout attacks are caused by the accumulation of uric acid crystals in a joint. They cause sudden and extremely intense pain, often in the big toe.¹¹

Muscle pain and soreness

Muscle soreness after exercise is a normal phenomenon called delayed onset muscle soreness (DOMS). It occurs 24 to 72 hours after unusual exertion and disappears within a few days.¹² This pain indicates that your muscles are adapting, not that they are damaged.

A sudden back strain or muscle spasm can also cause intense acute pain. Despite the sharp pain, these injuries generally heal well within a few weeks. To learn more, consult our guide on muscle pain.

Infections

Certain infections cause acute pain that requires prompt medical attention. Septic arthritis (joint infection) is a medical emergency.¹³ It manifests as a very hot, red, swollen joint, accompanied by fever.

How does your body heal after an acute injury?

Understanding the healing process helps you have realistic expectations and avoid unnecessary worry. Most tissues in the human body heal following a predictable three-phase pattern.¹⁴

Inflammatory phase (days 1 to 7)

Immediately after an injury, your body triggers an inflammatory response. The swelling, heat, redness, and pain you feel are signs of this response. Specialized cells arrive at the site to clear cellular debris and prepare for reconstruction.

This phase is necessary and beneficial, even if it's uncomfortable. Inflammation attracts the cells that will rebuild the damaged tissue. Completely blocking inflammation with medication can actually slow down healing.¹⁵

During this phase, you will likely experience the most pain and swelling. This is normal. Protecting the injured area is appropriate, but prolonged complete rest is generally not recommended.

Proliferation phase (days 4 to 21)

Specialized cells begin to create new tissue. In the case of a muscle injury, muscle cells multiply. For a ligament, fibroblasts (cells that produce collagen) generate new collagen.

The new tissue is initially fragile and disorganized. It resembles scar tissue more than the original tissue. This is why resuming intense activities too quickly can cause a new injury.

During this phase, gentle and progressive movement is beneficial. It stimulates the production of new tissue and helps the fibers align correctly. This is known as the principle of optimal loading.¹⁶

Remodeling Phase (weeks 3 to 12 months and beyond)

The new tissue gradually strengthens and reorganizes. The fibers align themselves in the direction of the mechanical forces they experience. The tissue becomes stronger and more functional.

This phase can last from several months to over a year for severe injuries. Even after complete healing, the repaired tissue doesn't always regain 100% of the original tissue's strength.

Here's a crucial point: Pain can significantly decrease before healing is complete. Relying solely on the disappearance of pain to resume normal activities is a common mistake that often leads to re-injury.¹⁷

When is acute pain at risk of becoming chronic?

The transition from acute to chronic pain doesn't happen by chance. Certain factors increase the risk of it becoming chronic. Identifying these early allows for intervention to prevent this progression.¹⁸

Biological Risk Factors

The intensity of the initial pain is an important factor. The more severe the acute pain, the higher the risk of it becoming chronic.¹⁹ Intense pain strongly activates your nervous system and can initiate the sensitization process.

Having chronic pain elsewhere in the body also increases the risk. Your nervous system may be more susceptible to developing sensitization.

Prolonged or uncontrolled inflammation can keep the body's alarm system on high alert, promoting the transition to chronic pain.

Psychological Risk Factors

Fear of movement, known as kinesiophobia, is a major risk factor. If you avoid moving due to fear of worsening your injury, you enter a vicious cycle. Prolonged immobility weakens your muscles, stiffens your joints, and paradoxically increases your sensitivity to pain.²⁰

Catastrophizing is when you imagine the worst-case scenario. For example, "I'll never heal," or "My back is ruined." These thoughts activate your stress system and can amplify your pain.

Untreated anxiety and depression significantly increase the risk of your acute pain becoming chronic. These conditions directly affect how your brain processes pain signals.²¹

Behavioral Risk Factors

Excessive rest beyond the first few days is rarely beneficial. Studies show that an early return to activities, adapted to your condition, promotes better healing.²²

Alternating between overactivity and crashing is another trap. You feel better, you do too much, and then you're bedridden for several days. This irregular pattern doesn't allow your body to adapt gradually.

Social Risk Factors

Lack of social support, conflicts at work or home, and financial difficulties related to disability can all contribute to pain becoming chronic.²³

A work environment that does not allow for adjustments or a gradual return can also be problematic.

How to Effectively Manage Acute Pain to Promote Healing?

Optimal management of acute pain is based on several principles. The goal is to control pain while promoting healing and preventing it from becoming chronic.

The POLICE Protocol for Injuries

The POLICE protocol has replaced the older RICE protocol. It emphasizes the importance of early movement rather than complete rest.²⁴

P for Protection. Protect the injured area to avoid further damage. Use crutches, a splint, or a bandage if necessary. This protection does not imply prolonged total immobilization.

OL for Optimal Loading. This is perhaps the most important element. Injured tissue needs to be exposed to appropriate mechanical stress to heal properly. Gentle and progressive movement stimulates tissue repair at the cellular level.²⁵

I for Ice. Ice helps control pain and swelling in the first few days. Apply it for 15 to 20 minutes, several times a day, protecting your skin with a cloth.

C for Compression. A compression bandage limits swelling and bleeding. It should not be so tight that it cuts off circulation.

E for Elevation. Elevating the injured limb above heart level helps drain excess fluid.

The Importance of Early Movement

Prolonged complete rest is almost never the right approach.²⁶ Even in the first few days after an injury, gentle movements within your pain limits are beneficial.

Movement increases blood flow to the injured area, bringing essential nutrients for repair. It prevents stiffness and muscle weakness. It also sends signals to the brain that the area can move, which helps normalize your pain perception.

The golden rule is to listen to your body. Mild pain during movement is acceptable. Pain that significantly worsens or persists after activity is a signal to slow down.

Pain Medication

Medications have their place in managing acute pain, but they are only one part of the solution.

Acetaminophen (Tylenol) is often the first choice for mild to moderate pain. It has few side effects when taken as directed.²⁷

Non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (Advil) or naproxen (Aleve) reduce inflammation and pain. They are particularly useful in the first few days. However, they can have side effects on the stomach and kidneys, especially with prolonged use.²⁸

Opioids are reserved for severe pain that does not respond to other treatments. They carry risks of dependence and significant side effects. Current guidelines recommend using them at the lowest possible dose for the shortest possible duration.²⁹

The goal of medication is not to eliminate pain completely, but to reduce it enough to allow you to move and function.

Early Physiotherapy

Consulting a physiotherapist quickly after an acute injury offers several benefits. The physiotherapist can accurately assess your injury and rule out serious issues. They can teach you exercises tailored to your healing stage. They can use manual techniques to reduce pain and improve mobility.³⁰

A study showed that people who consult a physiotherapist early after a back injury have better outcomes and use less medication than those who wait.³¹

How to Prevent Acute Pain from Becoming Chronic?

Preventing pain from becoming chronic starts in the first few days after an injury. Here are proven strategies.

Maintain appropriate activity levels

Complete rest beyond the first few days is rarely beneficial. Even during the acute phase, gentle and gradual movements promote healing.³² Physical activity releases endorphins (natural pain relievers produced by your body).

Find activities you can do despite your injury. If you can't run, can you walk? If walking is difficult, can you swim or use a stationary bike? Maintaining some physical activity is crucial for your physical and mental recovery.

Understand your pain

Knowledge is therapeutic. Understanding why you hurt reduces fear and anxiety, two major factors in pain becoming chronic.³³ Knowing that your pain is protective and temporary can reduce its perceived intensity.

Ask your healthcare professional questions. Ask for explanations about your condition, the expected healing time, and what you can and cannot do.

Manage stress factors

Stress, anxiety, and lack of sleep amplify pain. Your nervous system doesn't differentiate between physical and emotional stress. When you're stressed, your alarm system is on high alert.³⁴

Simple techniques can help. Deep breathing activates your parasympathetic nervous system, which promotes calm and recovery. A few minutes of slow breathing each day can make a difference.

Sleep is essential. It's during sleep that your body does most of its repair work. If pain disrupts your sleep, talk to your doctor.

Consult at the right time

Don't wait months to seek help if your pain isn't improving. Early intervention makes all the difference. If there's no significant improvement after 4 to 6 weeks, it's time to consult a professional if you haven't already.³⁵

A physiotherapist can identify factors that are slowing down your recovery and help you correct them before they become chronic problems.

How does physiotherapy help treat acute pain?

Physiotherapy is the recommended first-line intervention for most acute musculoskeletal pains. It offers a comprehensive approach that goes beyond just symptom relief.³⁶

The in-depth assessment

A physiotherapist begins with a detailed assessment of your condition. They examine your posture, how you move, your strength, and your flexibility. This assessment helps identify the cause of your pain and factors that might be slowing your recovery.

The assessment also includes a discussion about your activities, work, and goals. The treatment plan will be tailored to your specific situation.

Manual techniques

Manual therapy can provide rapid pain relief. Joint mobilizations guide the joint through ranges of motion it cannot achieve on its own. Soft tissue techniques relax tense muscles and improve circulation.³⁷

These techniques are not long-term solutions on their own, but they can create an opportunity for you to move and do your exercises with less pain.

Therapeutic Exercises

Exercises are the cornerstone of physiotherapy treatment. They are tailored to your stage of recovery and progress as you improve.³⁸

In the first few days, exercises aim to maintain mobility and prevent stiffness. Gradually, strengthening exercises are added. Finally, activity-specific exercises prepare you to resume your normal occupations.

Education

Education is a crucial component of treatment. Understanding your injury, the healing process, and what you can do to optimize it gives you a sense of control.³⁹ People who understand their condition achieve better results.

Your physiotherapist can help you distinguish between "normal" healing pain and pain that indicates a problem. This knowledge allows you to manage your activities appropriately.

When does acute pain require urgent attention?

The vast majority of acute pains are not dangerous and heal well with time and appropriate care. However, certain warning signs require prompt or immediate medical consultation.

Red Flags: Seek immediate emergency care

Cauda Equina Syndrome. This is a medical emergency requiring prompt surgical intervention.⁴⁰ Signs include loss of bladder or bowel control, numbness in the saddle area, progressive leg weakness, and severe lower back pain. If you experience these symptoms, go to the emergency room immediately.

Compartment Syndrome. Following a limb injury, pain that worsens despite medication, seems disproportionate to the injury, and is accompanied by tense swelling and a pale or cold limb requires immediate attention.⁴¹ Without prompt treatment, permanent damage can occur.

Signs of Infection. A very warm, red, and significantly swollen joint accompanied by fever can indicate a joint infection.⁴² This is an emergency requiring intravenous antibiotics and sometimes surgery.

Red Flags: Seek prompt consultation (within 24-48 hours)

Significant Trauma. A fall from a height, a car accident, or a severe blow warrants an evaluation to rule out a fracture or other serious injury, even if the pain seems tolerable.

Visible Deformity. A limb that appears twisted or displaced requires an evaluation to rule out a fracture or dislocation.

Inability to Bear Weight. If you are absolutely unable to put weight on a limb after an injury, a medical evaluation is necessary.

Severe Night Pain. Pain that wakes you up at night and is not relieved by changing position can sometimes indicate a more serious problem.

When to consult a healthcare professional

Even without red flags, consult a professional if your pain does not improve at all after one to two weeks, if it significantly limits your daily activities, if you need to take painkillers regularly for more than a week, or if you are unsure about the cause of your pain.

Frequently Asked Questions About Acute Pain

Is acute pain always related to tissue injury?

Not necessarily. Pain is an experience created by your brain to protect you. It can occur even without actual tissue damage if your brain perceives a threat.⁴³ That said, most acute pain is indeed related to tissue irritation or injury.

Should I apply heat or ice to my injury?

In the first few days (acute inflammatory phase), ice is generally preferred. It helps reduce swelling and numbs the pain. After a few days, heat can be beneficial for relaxing muscles and improving circulation. Some people alternate between the two. Listen to your body and use what provides the most relief.⁴⁴

How long should I wait before returning to sports after an injury?

It depends on the injury, its severity, and the sport you play. The absence of pain does not mean that healing is complete. A Grade I ankle sprain may allow a return to sports in 2-3 weeks. A Grade III sprain may require 3-6 months.⁴⁵ Consult a professional for a personalized recommendation.

Why does my pain vary from day to day?

This is normal. Your pain level depends on many factors. Sleep, stress, physical activity, weather, and your mood can all influence your perception of pain.⁴⁶ Day-to-day variation does not mean you are worsening your injury.

Does "feeling pain" during exercises mean that I am injuring myself?

Mild pain during rehabilitation exercises is often acceptable and even expected. The general rule is that pain should not exceed 3 or 4 out of 10, and should return to its baseline level within 24 hours after exercise.⁴⁷ Pain that gradually worsens or persists is a signal to modify the exercise.

Do Anti-inflammatories Slow Down Healing?

This is a debated topic. Inflammation is a necessary part of the healing process. Completely blocking inflammation could theoretically slow down tissue repair.⁴⁸ However, in practice, anti-inflammatories taken at recommended doses for a short period do not seem to have a significant negative effect on healing for most people. Discuss this with your doctor or pharmacist.

When can I stop protecting my injury?

Intense protection (splint, crutches) is generally only necessary in the first few days. After that, a gradual progression towards normal activities is beneficial. Prolonged protection can lead to stiffness, weakness, and increased sensitivity.⁴⁹ Your physiotherapist can guide you through this progression.

Key Takeaways

Acute pain is a normal and necessary protective signal. It warns you that there is a problem and encourages you to take care of yourself. The vast majority of acute pain improves with time and appropriate care.

Optimal management of acute pain involves a balance between protection and movement. Prolonged complete rest is rarely the right approach. Adapted, progressive movement within tolerable limits promotes better healing.

Psychological factors play an important role. Fear, avoidance, and catastrophizing can transform acute pain into chronic pain. Understanding your pain and staying active are key elements of prevention.

If your pain does not improve after a few weeks or if you experience red flags, consult a healthcare professional. Early intervention can make all the difference between a complete recovery and the development of persistent pain.

Are you experiencing acute pain affecting your back, neck, shoulders or knees? Our physiotherapists can assess your condition and guide you towards optimal recovery.

Sources

¹ International Association for the Study of Pain (IASP). Definition of Pain. 2020.

² World Health Organization (WHO). ICD-11 Classification of Chronic Pain. 2019.

³ Cox JJ, et al. An SCN9A channelopathy causes congenital inability to experience pain. Nature. 2006.

⁴ Basbaum AI, et al. Cellular and molecular mechanisms of pain. Cell. 2009.

⁵ Moseley GL. Reconceptualising pain according to modern pain science. Physical Therapy Reviews. 2007.

⁶ IASP Task Force. A classification of chronic pain for ICD-11. Pain. 2015.

⁷ Woolf CJ. Central sensitization: implications for the diagnosis and treatment of pain. Pain. 2011.

⁸ Waterman BR, et al. The epidemiology of ankle sprains in the United States. Journal of Bone and Joint Surgery. 2010.

⁹ Chou R, et al. Management of Postoperative Pain: A Clinical Practice Guideline. Journal of Pain. 2016.

¹⁰ Sayegh ET, Strauch RJ. Treatment of olecranon bursitis: a systematic review. Archives of Orthopaedic and Trauma Surgery. 2014.

¹¹ Dalbeth N, et al. Gout. Lancet. 2016.

¹² Cheung K, et al. Delayed onset muscle soreness: treatment strategies and performance factors. Sports Medicine. 2003.

¹³ Goldenberg DL. Septic arthritis. Lancet. 1998.

¹⁴ Reinke JM, Sorg H. Wound repair and regeneration. European Surgical Research. 2012.

¹⁵ Duchesne E, et al. Impact of inflammation and anti-inflammatory modalities on skeletal muscle healing. Antioxidants. 2017.

¹⁶ Khan KM, Scott A. Mechanotherapy: how physical therapists' prescription of exercise promotes tissue repair. British Journal of Sports Medicine. 2009.

¹⁷ Bleakley CM, et al. The use of ice in the treatment of acute soft-tissue injury. American Journal of Sports Medicine. 2004.

¹⁸ Vos CJ, et al. Clinical course and prognostic factors in acute neck pain. Pain. 2008.

¹⁹ Katz J, Seltzer Z. Transition from acute to chronic postsurgical pain: risk factors and protective factors. Expert Review of Neurotherapeutics. 2009.

²⁰ Vlaeyen JW, Linton SJ. Fear-avoidance and its consequences in chronic musculoskeletal pain. Pain. 2000.

²¹ Pinheiro MB, et al. Symptoms of depression and risk of new episodes of low back pain. Arthritis Care & Research. 2015.

²² Waddell G. The Back Pain Revolution. Churchill Livingstone. 2004.

²³ Turk DC, Okifuji A. Psychological factors in chronic pain: evolution and revolution. Journal of Consulting and Clinical Psychology. 2002.

²⁴ Bleakley CM, et al. PRICE needs updating, should we call the POLICE? British Journal of Sports Medicine. 2012.

²⁵ Glasgow P, et al. Optimal loading: key variables and mechanisms. British Journal of Sports Medicine. 2015.

²⁶ Dahm KT, et al. Advice to rest in bed versus advice to stay active for acute low-back pain and sciatica. Cochrane Database of Systematic Reviews. 2010.

²⁷ Ennis ZN, et al. Acetaminophen for Chronic Pain. Annals of Internal Medicine. 2015.

²⁸ Derry S, et al. Topical NSAIDs for acute musculoskeletal pain in adults. Cochrane Database of Systematic Reviews. 2015.

²⁹ Dowell D, et al. CDC Clinical Practice Guideline for Prescribing Opioids for Pain. MMWR. 2022.

³⁰ Foster NE, et al. Prevention and treatment of low back pain: evidence, challenges, and promising directions. Lancet. 2018.

³¹ Fritz JM, et al. Primary care referral of patients with low back pain to physical therapy. Spine. 2012.

³² Malmivaara A, et al. The treatment of acute low back pain: bed rest, exercises, or ordinary activity? New England Journal of Medicine. 1995.

³³ Louw A, et al. The effect of neuroscience education on pain, disability, anxiety, and stress in chronic musculoskeletal pain. Archives of Physical Medicine and Rehabilitation. 2011.

³⁴ Hannibal KE, Bishop MD. Chronic stress, cortisol dysfunction, and pain. Psychoneuroendocrinology. 2014.

³⁵ Hill JC, et al. A primary care back pain screening tool: identifying patient subgroups for initial treatment. Arthritis & Rheumatism. 2008.

³⁶ Chou R, et al. Nonpharmacologic Therapies for Low Back Pain. Annals of Internal Medicine. 2017.

³⁷ Bialosky JE, et al. The mechanisms of manual therapy in the treatment of musculoskeletal pain. Manual Therapy. 2009.

³⁸ Hayden JA, et al. Exercise therapy for chronic low back pain. Cochrane Database of Systematic Reviews. 2021.

³⁹ Moseley GL, Butler DS. Fifteen Years of Explaining Pain: The Past, Present, and Future. Journal of Pain. 2015.

⁴⁰ Gardner A, et al. Cauda equina syndrome. BMJ. 2011.

⁴¹ Via AG, et al. Acute compartment syndrome. Muscles, Ligaments and Tendons Journal. 2015.

⁴² Mathews CJ, et al. Septic arthritis: current diagnostic and therapeutic algorithm. Current Opinion in Rheumatology. 2008.

⁴³ Moseley GL. A pain neuromatrix approach to patients with chronic pain. Manual Therapy. 2003.

⁴⁴ Malanga GA, et al. Mechanisms and efficacy of heat and cold therapies for musculoskeletal injury. Postgraduate Medicine. 2015.

⁴⁵ Kaminski TW, et al. National Athletic Trainers' Association position statement: conservative management and prevention of ankle sprains in athletes. Journal of Athletic Training. 2013.

⁴⁶ Edwards RR, et al. Patient phenotyping in clinical trials of chronic pain treatments. Pain. 2016.

⁴⁷ Thomée R. A comprehensive treatment approach for patellofemoral pain syndrome in young women. Physical Therapy. 1997.

⁴⁸ Schoenfeld BJ. The use of nonsteroidal anti-inflammatory drugs for exercise-induced muscle damage. Sports Medicine. 2012.

⁴⁹ Kerkhoffs GM, et al. Immobilisation for acute ankle sprain. Cochrane Database of Systematic Reviews. 2001.