Injury Science and Tissue Healing

Healing runs through overlapping phases: inflammation (days), proliferation or repair (weeks), then remodelling (months).

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · recall

Fibroblasts lay down new collagen and new capillaries form over roughly the first few weeks.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · recall

Early repair tissue is rich in thinner type III collagen, gradually replaced by stronger type I during remodelling.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · recall

Remodelling realigns and strengthens collagen along the lines of load, a process that runs for months to over a year.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · recall

Collagen fibres orient in response to mechanical load, so graded loading produces a better organised, stronger repair.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · applied

Dubois and Esculier proposed PEACE (first days) and LOVE (after) in 2020 to update RICE and POLICE with load and education.

Source: Dubois & Esculier, Br J Sports Med 2020 · recall

Inflammation is part of repair, and anti-inflammatories may impair long-term tissue healing, especially at higher doses.

Source: Dubois & Esculier, Br J Sports Med 2020 · recall

Ice can relieve pain short term, but there is little high-quality evidence that it improves healing, and it may blunt inflammation.

Source: Dubois & Esculier, Br J Sports Med 2020 · recall

Mechanical load promotes repair and tissue capacity, so normal activity returns as soon as symptoms allow.

Source: Dubois & Esculier, Br J Sports Med 2020 · recall

Pain settles long before collagen has matured; tensile strength keeps recovering for months.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · applied

Osteoclasts resorb bone; osteoblasts then lay down new bone in the same spot.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · recall

Osteoblasts form new bone matrix, which later mineralises.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · recall

Bone remodels to match the mechanical demands on it, adding mass where loads are high.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · recall

Remodelling removes bone first and refills it over months, leaving a window of reduced strength.

Source: Warden et al., Curr Osteoporos Rep 2014 · applied

A full cycle of resorption, reversal and formation lasts several months in adult bone.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · recall

Bone responds best to high, fast, varied strains; breaking loading into bouts with rest improves the response.

Source: Robling et al., J Bone Miner Res 2002 · recall

Non-weight-bearing sports provide little osteogenic stimulus, so athletes relying on them can have low bone density.

Source: Scofield & Hecht, Curr Sports Med Rep 2012 · applied

Most bone mass is gained by the end of adolescence; peak is reached in the twenties.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · recall

Vitamin D increases calcium absorption; deficiency is linked to higher bone stress injury risk.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · recall

Frost proposed that bone senses strain and adds or removes mass when strain moves above or below set thresholds.

Source: Frost, Anat Rec 1987 · recall

Repeated loading beyond repair capacity causes a spectrum from bone marrow oedema to a complete fracture line.

Source: Warden et al., Curr Osteoporos Rep 2014 · recall

Early X-rays miss most bone stress injuries; changes may appear only after two to three weeks as healing bone forms.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · recall

MRI shows bone marrow oedema early and allows the injury to be graded.

Source: Fredericson et al., Am J Sports Med 1995 · recall

Fredericson graded tibial stress injuries on MRI from periosteal oedema to a visible fracture line.

Source: Fredericson et al., Am J Sports Med 1995 · recall

High-risk sites (femoral neck, navicular, anterior tibia, fifth metatarsal base) heal poorly and can displace or fail to unite.

Source: Warden et al., Curr Osteoporos Rep 2014 · recall

Sites under tension or with poor blood supply risk non-union or displacement, sometimes needing surgery.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · recall

An anterior tibial cortex fracture line signals a high-risk injury with a real risk of non-union.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · recall

Navicular stress fractures are high-risk because of the bone's poor central blood supply.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · recall

Posteromedial tibial and most metatarsal shaft injuries are low-risk and usually heal with load modification.

Source: Warden et al., Curr Osteoporos Rep 2014 · recall

Low energy availability suppresses bone formation, a major modifiable risk factor for bone stress injury.

Source: Mountjoy et al., Br J Sports Med 2023 (IOC REDs consensus) · recall

Tendon is dense connective tissue made largely of parallel type I collagen fibres.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · recall

Chronic tendon pain shows disorganised matrix rather than classic inflammation, so "tendinopathy" is preferred.

Source: Khan et al., BMJ 2002 · recall

The model places tendinopathy on a continuum from reactive tendinopathy through tendon dysrepair to degeneration.

Source: Cook & Purdam, Br J Sports Med 2009 · recall

Acute overload, such as a jump in volume or a return to hills or speed, triggers the reactive stage.

Source: Cook & Purdam, Br J Sports Med 2009 · recall

Tendon matrix turns over slowly, so tendons lag behind muscles when load increases quickly.

Source: Magnusson et al., Nat Rev Rheumatol 2010 · recall

The Achilles stretches as the foot lands and recoils at push-off, saving metabolic energy.

Source: Alexander, J Exp Biol 1991 · recall

Peak Achilles forces in running reach roughly six to eight times body weight.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · recall

A stiffer tendon lengthens less for a given force, transmitting muscle force faster.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · recall

Tendons respond to high loads with greater stiffness and, over time, some increase in size.

Source: Bohm et al., Sports Med Open 2015 · recall

The mid-portion, about 2-6 cm above the insertion, has a relatively poor blood supply and is where most tendinopathy occurs.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · recall

Alfredson prescribed 3 x 15 eccentric heel drops with straight and bent knee, twice daily, for 12 weeks.

Source: Alfredson et al., Am J Sports Med 1998 · recall

HSR uses heavy loads with slow concentric and eccentric phases, usually three sessions a week.

Source: Kongsgaard et al., Scand J Med Sci Sports 2009 · recall

Both groups improved similarly at 12 weeks and one year; patient satisfaction tended to be higher with HSR.

Source: Beyer et al., Am J Sports Med 2015 · recall

A single session of heavy isometrics reduced pain for at least 45 minutes; later studies found the effect less consistent.

Source: Rio et al., Br J Sports Med 2015 · recall

Continuing to run was allowed if pain stayed at or below 5/10 and did not increase the next morning.

Source: Silbernagel et al., Am J Sports Med 2007 · recall

Tendons need load to maintain their properties; prolonged rest reduces stiffness and capacity.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · recall

Their 2010 Lancet review found injections helped in weeks but were linked to poorer results and more recurrence later.

Source: Coombes et al., Lancet 2010 · recall

The large ATM trial found no benefit of PRP over placebo injection for chronic Achilles tendinopathy.

Source: Kearney et al., JAMA 2021 · recall

Tendon cells respond to mechanical load by remodelling matrix; passive options at best ease symptoms.

Source: Cook & Purdam, Br J Sports Med 2009 · applied

A next-morning rise in pain or stiffness is the key sign the previous load exceeded tendon tolerance.

Source: Silbernagel et al., Am J Sports Med 2007 · applied

The myotendinous junction is the weakest link in the muscle-tendon unit under eccentric load.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · recall

In late swing the hamstrings decelerate the shank while lengthening, the moment of highest strain risk.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · recall

Programmes including Nordic hamstring exercises reduced hamstring injury rates by roughly 50%.

Source: van Dyk et al., Br J Sports Med 2019 · recall

BAMIC grades 0-4 plus a, b or c; "c" injuries extend into the tendon and take longer to return from.

Source: Pollock et al., Br J Sports Med 2014 · recall

Injuries involving the tendon within the muscle have longer return times and higher re-injury rates.

Source: Pollock et al., Br J Sports Med 2014 · recall

Medial gastrocnemius strains ("tennis leg") are typical of middle-aged and older athletes.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · recall

Schwellnus and others argue fatigue-related neuromuscular changes explain cramps better than dehydration or electrolyte loss alone.

Source: Schwellnus, Br J Sports Med 2009 · recall

Cramps eased in about 85 seconds, too fast for absorption, suggesting a reflex from the mouth or throat.

Source: Miller et al., Med Sci Sports Exerc 2010 · recall

Passive stretching reduces the abnormal nerve activity driving the cramp.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · recall

Incomplete rehabilitation leaves weaker, less extensible tissue, raising the risk of re-injury.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · applied

Tissues fail when applied load outstrips their current capacity; training should raise capacity faster than load.

Source: Bertelsen et al., Scand J Med Sci Sports 2017 · recall

It compares, for example, the last week's load with the average of the last four weeks.

Source: Gabbett, Br J Sports Med 2016 · recall

Gabbett suggested injury risk was lowest when the ratio stayed around 0.8-1.3 and rose above about 1.5.

Source: Gabbett, Br J Sports Med 2016 · recall

Critics showed mathematical coupling, poor statistical properties and little evidence it predicts injury in individuals.

Source: Impellizzeri et al., Int J Sports Physiol Perform 2020 · recall

Novices following a 10%-per-week build had similar injury rates to a group progressing faster.

Source: Buist et al., Am J Sports Med 2008 · recall

Runners who increased weekly volume by more than 30% had more distance-related injuries than those under 10%.

Source: Nielsen et al., J Orthop Sports Phys Ther 2014 · recall

Incidence across studies ranged from about 19% to 79%, most often in the lower limb, especially the knee.

Source: van Gent et al., Br J Sports Med 2007 · recall

Capacity depends on training history, body mass, biomechanics, sleep, energy and more, so identical loads land differently.

Source: Bertelsen et al., Scand J Med Sci Sports 2017 · applied

Load is tissue-specific; cycling and swimming hours put little impact through the tibia.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · applied

Rapid, unaccustomed increases in load, rather than high load itself, are most strongly linked to injury.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · recall

Pain is produced by the brain in response to perceived threat and is shaped by context, not a readout of tissue damage.

Source: Moseley & Butler, J Pain 2015 · recall

Nerve signalling of potential harm can occur without pain, and pain can occur without nociception.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · recall

The central nervous system amplifies signals, so normal inputs can hurt more and pain spreads.

Source: Woolf, Pain 2011 · recall

Disc degeneration appeared in 37% of pain-free 20-year-olds and 96% of pain-free 80-year-olds.

Source: Brinjikji et al., AJNR Am J Neuroradiol 2015 · recall

Mild, settling pain during graded rehabilitation does not necessarily mean further damage.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · applied

Fear of pain leads to avoidance, deconditioning and often more pain and disability.

Source: Vlaeyen & Linton, Pain 2000 · recall

Sleep loss lowers pain thresholds and stress amplifies pain processing.

Source: Finan et al., J Pain 2013 · recall

A bout of exercise usually lowers pain sensitivity for a while afterwards.

Source: Rice et al., J Pain 2019 · recall

Teaching patients the biology of pain can reduce pain and disability, especially combined with exercise.

Source: Louw et al., Physiother Theory Pract 2016 · recall

Rotator cuff tears are frequent in pain-free people, so scan findings must be matched to symptoms and examination.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · applied

Incidence counts new cases over a period, often expressed per 1,000 hours of exposure.

Source: Bahr et al., Br J Sports Med 2020 (IOC consensus) · recall

Prevalence captures all current cases, new and ongoing, which suits overuse problems.

Source: Bahr et al., Br J Sports Med 2020 (IOC consensus) · recall

Many overuse problems reduce performance without stopping training, so they escape a time-loss count.

Source: Clarsen et al., Br J Sports Med 2013 · recall

The Oslo Sports Trauma Research Center questionnaire records participation, modified training, performance and pain each week.

Source: Clarsen et al., Br J Sports Med 2013 · recall

Previous injury is the most consistently reported predictor of a new running injury.

Source: van der Worp et al., PLoS One 2015 · recall

Normalising by exposure time allows comparison of groups with very different training volumes.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · applied

Observational data show association; confounding factors may explain the link.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · applied

Randomisation balances known and unknown confounders between groups.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · recall

Fokkema and colleagues found the online programme did not reduce injuries in recreational runners.

Source: Fokkema et al., Br J Sports Med 2019 · recall

Multifactorial causes, low event rates and poor adherence make prevention effects hard to detect.

Source: Bahr et al., Br J Sports Med 2020 (IOC consensus) · applied

Fairclough showed the band is anchored to the femur and cannot slide; compression of richly innervated tissue is the likely cause.

Source: Fairclough et al., J Anat 2006 · recall

Exercise therapy targeting hip and knee muscles is recommended to reduce pain and improve function.

Source: Crossley et al., Br J Sports Med 2016 · recall

Heel raises with a towel under the toes gave better results at three months than plantar fascia stretching.

Source: Rathleff et al., Scand J Med Sci Sports 2015 · recall

MTSS causes diffuse pain along the posteromedial tibia; focal tenderness suggests a bone stress injury.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · recall

Pressure on the ulnar nerve in Guyon's canal causes numbness and weakness in the ring and little fingers.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · recall

Saddle pressure on the perineum can compress the pudendal nerve and reduce blood flow.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · recall

Repeated hip flexion in an aero position can thicken the artery wall, causing one-sided leg pain and weakness at high power.

Source: Peach et al., Eur J Vasc Endovasc Surg 2012 · recall

At low power the flow needed passes the narrowing; at high power it cannot, so symptoms appear.

Source: Peach et al., Eur J Vasc Endovasc Surg 2012 · applied

Repeated impact and eccentric loading in running stress bone and tendon far more than cycling.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · applied

Lateral knee pain aggravated by downhill running, around 30 degrees of knee flexion, is typical of ITBS.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · applied