Hamstring Injuries: Why They Keep Coming Back

Hamstring injuries do not keep recurring because you need more rest. They recur because the muscle is returned to sport before it is genuinely ready, and the markers most athletes use to judge readiness are the wrong ones. Pain settling is not the same as strength restored. Jogging comfortably is not the same as high-speed running capacity recovered. And time elapsed since injury is perhaps the least reliable marker of all. Understanding this gap between feeling ready and being ready is the most important thing any athlete with a recurrent hamstring problem can grasp.

• Want to understand the different types of hamstring injury first? Read: Understanding Hamstring Injuries

Why Hamstrings Get Injured

The Anatomy

The hamstring is a group of three muscles, the biceps femoris, semitendinosus, and semimembranosus, that run down the back of the thigh and cross both the hip and the knee. This dual crossing means they must simultaneously control movement at two joints under rapidly changing loads. During high-speed running, the hamstrings work hardest in the late swing phase just before foot strike, when they are decelerating the lower leg while simultaneously lengthening under tension. This combination of high force and high speed creates significant mechanical demand through the tissue. When that demand exceeds what the muscle can currently handle, fibres tear.

Where the Injury Occurs Matters

Not all hamstring injuries are the same, and where the tear occurs influences how it is managed.

• For a more detailed breakdown of injury types, see: Understanding Hamstring Injuries

• Proximal tears occur at the top of the thigh near the ischial tuberosity. These range from mild strains to complete proximal tendon avulsions, which may require surgical assessment.
• Mid-belly tears affect the main body of the muscle and often have favourable healing potential, although prognosis still depends on the extent and exact location of the injury.
• Musculotendinous junction (MTJ) tears involve the zone where the muscle transitions into tendon. The anatomy and tissue characteristics at this location mean the injury can present differently and may require a different loading strategy. Rehabilitation needs to be tailored to the injured tissue, the severity, and the demands of the athlete's sport.
• Distal tears occur closer to the back of the knee and are less common.

Why Hamstring Injuries Keep Recurring

The Numbers

Recurrence rates of between 14% and 63% have been reported in the same playing season or up to two years after the original injury. Systematic reviews have consistently identified previous hamstring injury as one of the most significant risk factors for a subsequent tear, with a 2 to 6 times higher rate of recurrence in athletes with prior injury. A prospective study of athletes in sprint and high-speed running events found that those with prior injury had an odds ratio of 2.85 for re-injury. These are not coincidences. They reflect a consistently repeated pattern: athletes returning to sport before the muscle is genuinely ready.

The Athlete Feels Better Before the Hamstring Is Ready

Pain reduces relatively early in the recovery process, often well before the hamstring has restored its strength, its capacity for eccentric loading, and its ability to tolerate high-speed running. The athlete feels comfortable. Slow jogging feels fine. The decision is made to return. Then they sprint, decelerate sharply, or change direction at pace, and it tears again. The progression from pain reduction to genuine readiness involves distinct stages that must each be worked through:

• Appropriate protection and load management in the early phase, allowing the initial response to settle without unnecessary loss of strength from prolonged unloading.
• Progressive strengthening, building the capacity of the muscle systematically before returning to running.
• Progressive running exposure, from pain-free jogging through to submaximal and then maximal velocity work.
• Sport-specific demands, replicating the actual patterns of acceleration, deceleration, change of direction, and repeated sprint effort the athlete will encounter in competition.

Returning before the tissue and the neuromuscular system can actually support each stage is where re-injury risk compounds.

What the Evidence Says About Rehabilitation

Early Loading, With Appropriate Progression

Modern hamstring rehabilitation does not require prolonged rest before strengthening begins. Prolonged unloading leads to loss of strength and physical capacity and does nothing to prepare the athlete for the demands of running and sprinting. High-intensity eccentric loading can be introduced relatively early in rehabilitation when exercise-specific progression criteria are met. The framework is not rest versus loading. It is: appropriate protection, then progressive loading, then progressive running exposure, then high-speed running, then sport-specific demands. Each stage earns the next.

Eccentric Loading: An Important Component, Not the Whole Answer

Eccentric exercises are an important component of hamstring rehabilitation. They can improve muscle strength and capacity at longer muscle lengths, helping the hamstring tolerate the high-force, high-speed demands of sprinting. The evidence supports eccentric training as part of a comprehensive programme that also includes progressive running, strengthening across multiple positions, and stabilisation work. A 2015 systematic review and meta-analysis found that adding eccentric rehabilitation exercises to a conventional programme significantly improved return-to-play time, with a hazard ratio of 3.22. This study did not demonstrate a significant reduction in reinjury rate, which underlines that eccentric loading is one important component of a broader programme, not the complete solution. The Nordic hamstring exercise is the most studied eccentric hamstring intervention and has been consistently associated with meaningful reductions in hamstring injury incidence when incorporated systematically into training programmes with adequate adherence.

• For a detailed breakdown of what rehabilitation involves at each stage, see: Hamstring Injury Treatment: What the Evidence Says

Stretching: Part of the Programme, Not the Solution

Stretching has a role in hamstring rehabilitation but should not be mistaken for a substitute for progressive strengthening and running exposure. The goal is not to make the hamstring feel looser, it is to restore its capacity to tolerate force and high-speed lengthening. Early in rehabilitation, aggressive stretching may be inappropriate depending on the injury location and tissue irritability. As symptoms settle, mobility work can be incorporated alongside progressive strengthening and running as part of a comprehensive programme.

The IP Physio Return-to-Sport Assessment

We do not ask how many weeks have passed since the injury. We ask what the hamstring can actually do. Return-to-sport clearance at IP Physio is based on a multidimensional assessment across seven areas:

• Strength testing and performance diagnostics

• 1. Symptoms: acceptable symptoms under progressively higher loads, with no significant post-session reaction indicating the tissue is being exceeded.
• 2. Strength: objective testing using hand-held dynamometry across multiple positions. Bilateral comparison. Absolute strength relative to body mass where appropriate. Feeling strong is not the same as testing strong.
• 3. High-speed running capacity: progressive acceleration, submaximal running, maximum velocity exposure, and repeated sprint exposure. The hamstring must have experienced the speeds it will face in competition before it faces them.
• 4. Eccentric capacity: lengthened-position strength, Nordic hamstring capacity, and sport-specific eccentric loading.
• 5. Functional performance: running mechanics, acceleration and deceleration patterns, change of direction, and sport-specific tasks. We use ForceDecks force plate assessment to evaluate force production during dynamic movements, because peak strength and the rate at which force can be generated are distinct qualities. Peak strength is only part of the picture, understanding how quickly the athlete can produce force is particularly relevant when their sport demands rapid acceleration, sprinting, and change of direction.
• 6. Psychological readiness: low confidence can influence how an athlete moves and performs when returning to sport, which is why psychological readiness is considered alongside physical testing.
• 7. Training tolerance: can they sustain the actual workload they will face after returning? A single session is not the same as two weeks of full training.

The Diagnostic Tools We Use

• Diagnostic ultrasound
• Strength testing and performance diagnostics
• Gait and running analysis

• Musculoskeletal ultrasound: where clinically indicated, we image the hamstring to confirm the location and extent of the tear. Knowing whether the injury involves the muscle belly, the MTJ, or the proximal tendon informs the loading programme from day one.
• Hand-held dynamometry: objective strength measurement at regular intervals throughout rehabilitation, giving a precise picture of bilateral strength and how it is evolving over time.
• ForceDecks force plates: assessment of force production during dynamic tasks to complement the strength testing picture.
• Running analysis: can identify changes in running mechanics following injury that may be relevant when progressing back to high-speed running and sport.

If you are dealing with a hamstring injury that keeps returning, or one you want to manage properly from the start, get in touch with us today.

• Have a specific question? See the Hamstring Injury FAQ

References

• Martin RL, Cibulka MT, Bolgla LA, et al. Hamstring strain injury in athletes: clinical practice guidelines. J Orthop Sports Phys Ther. 2022;52(3):CPG1-CPG44. doi:10.2519/jospt.2022.0301.
• Freckleton G, Pizzari T. Risk factors for hamstring muscle strain injury in sport: a systematic review and meta-analysis. Br J Sports Med. 2013;47(6):351-358. doi:10.1136/bjsports-2011-090664.
• de Visser HM, Reijman M, Heijboer MP, Bos PK. Risk factors of recurrent hamstring injuries: a systematic review. Br J Sports Med. 2012;46(2):124-130. doi:10.1136/bjsports-2011-090317.
• van der Horst N, Smits DW, Petersen J, et al. The preventive effect of the Nordic hamstring exercise on hamstring injuries in amateur soccer players: a randomised controlled trial. Am J Sports Med. 2015;43(6):1316-1323. doi:10.1177/0363546515574057.
• Pas HIMFL, Reurink G, Tol JL, et al. Efficacy of rehabilitation (lengthening) exercises, platelet-rich plasma injections, and other conservative interventions in acute hamstring injuries: an updated systematic review and meta-analysis. Br J Sports Med. 2015;49(18):1197-1205.
• Hickey JT, Rio E, Best TM, et al. Early introduction of high-intensity eccentric loading into hamstring strain injury rehabilitation. J Sci Med Sport. 2022;25(9):732-736. doi:10.1016/j.jsams.2022.06.002.
• Tedeschi R, Fari G, Giorgi F, et al. Strengthening football: the role of the Nordic hamstring exercise in preventing hamstring injuries. J Back Musculoskelet Rehabil. 2026;39(4):1137-1147. doi:10.1177/10538127251326736.