If you felt a sudden sharp pull in the back of your thigh while sprinting, lunging or pushing off, you most likely strained a hamstring, and most strains heal without surgery. The best-supported path is a short stretch of protection, then early and progressive strengthening that loads the muscle while it lengthens. Return takes from a couple of weeks to a few months depending on how much of the muscle tore. A few signs point to something worse: a tendon torn off the bone, which a surgeon should see.
How are hamstring strains graded?
Doctors grade a strain by how much of the muscle failed. StatPearls describes grade I as minor fiber damage with minimal pain, grade II as a partial tear with pronounced pain and measurable weakness, and grade III as a complete tear with severe pain, bruising and marked weakness. The AAOS adds that a grade 3 injury may take months to heal.
Imaging grades are a separate scale, and they predict time away from sport. In a 2012 study of 516 hamstring injuries in professional football, MRI grades 0, 1, 2 and 3 meant average lay-offs of 8, 17, 22 and 73 days. That is an elite male sample from more than three years ago, so read it as a pattern and expect your own timeline to differ. Most recreational players never get an MRI, and a clinician's exam usually sets the plan.
Which signs mean a torn-off tendon and a surgeon?
The most severe hamstring injury is an avulsion: the tendon tears completely away from the sitting bone, sometimes taking a piece of bone with it. The AAOS says surgery is most often done for these, rather than for tears inside the muscle belly. Get seen promptly if you notice any of these:
- Heavy bruising and swelling high in the back of the thigh. Bruising also appears in ordinary strains, so weigh it with the other signs. A 2024 review lists tenderness at the sitting bone, bruising and weakness as typical of proximal injuries, and both patients in the case report below had a large bruise or swelling.
- A tearing or popping feeling at the moment of injury. StatPearls notes severe injuries may produce an audible pop.
- A visible or palpable gap just below the sitting bone, or a muscle that has bunched up. The AAOS shows a photo of the muscle "balled up" at the back of the thigh after a complete tear, and a case report of two complete ruptures found a palpable gap in both patients.
- Marked weakness bending the knee or pushing the leg back, or trouble sitting.
Why it matters: a 2024 review found that complete three-tendon tears pulled back more than 2 cm have worse outcomes and more complications. A 2021 systematic review found surgery enabled earlier return to play for proximal injuries, while muscle-belly injuries did well without it. Repair brings its own long rehab: the AAOS puts it at six months or more. Sciatica and low back problems can also send pain down the thigh; our sciatica guide covers that look-alike.
What should you do in the first days?
For the first one to three days, protect the leg, then start moving it. The 2020 PEACE and LOVE editorial in the British Journal of Sports Medicine lays this out: protect (unload for one to three days), raise the leg, avoid anti-inflammatory medication, add compression, and educate yourself; then, after the first days, load, keep an optimistic outlook, add pain-free cardio for blood flow, and exercise.
Two honest notes. That editorial is an expert opinion rather than a trial, and it questions both ice and anti-inflammatory medication, while the AAOS still teaches rest, ice, compression and a raised leg. Ask your clinician which you should follow. And the editorial says passive treatments early after injury have insignificant effects on pain and function compared with an active approach. Remember that when you compare options later in this guide.
What is the best hamstring strain recovery program?
Progressive strengthening that loads the hamstring while it lengthens has the strongest evidence. A 2015 meta-analysis found lengthening exercises cut time to return to play (hazard ratio 3.22) with no difference in reinjury. A 2023 meta-analysis agreed that loading helps athletes return on time.
The anchor trials are Carl Askling's two randomized trials of the "L-protocol," built around loading the hamstrings during maximal lengthening. Among elite Swedish footballers, return took a mean of 28 days versus 51 on conventional exercises. Among elite sprinters and jumpers, it took 49 days versus 86. The Nordic hamstring exercise, where you lower your body forward from kneeling against resistance, is the best-known lengthening move. One 2022 study introduced it, with a slider, a median of five days after injury in supervised rehab. Know the limits: the trials were small, the athletes elite, and a Danish evidence review rated the evidence very low to low quality.
How much pain is acceptable? A randomized trial of 43 men compared pain-free with pain-threshold rehab. Return to play came at a median 15 versus 17 days, no significant difference, but the pain-threshold group regained more strength. Your physical therapist sets that line.
How long until you can run or play again?
Sources report wide ranges because the injuries differ. Use this table as a map; your own timeline will differ.
| Source and group | What it reports |
|---|---|
| 2012 MRI study, 516 injuries in pro football | Average lay-off 8, 17, 22 and 73 days for MRI grades 0 to 3 |
| Askling 2013, elite footballers | 28 days (L-protocol) versus 51 days (conventional) |
| Askling 2014, elite sprinters and jumpers | 49 versus 86 days; injuries involving the free tendon near the sitting bone took 73 versus 31 days on the L-protocol |
| Hickey 2020, 43 men in supervised rehab | Median 15 to 17 days to clearance |
| AAOS, tendon repair | At least six months of rehab for a proximal repair |
Feeling fine is not proof the muscle has healed. In a 2013 trial, every participant had near-complete pain relief and strength at return to sport, yet none showed a fully resolved injury on MRI. Return on the date your clinician clears, whatever the leg feels like on a good day.
How do you keep a hamstring strain from coming back?
Reinjury is the hamstring's reputation. StatPearls reports about one in three athletes are reinjured within a year of returning. Two things have evidence behind them.
First, the Nordic hamstring exercise as prevention. A 2019 meta-analysis of 15 studies and 8,459 athletes found programs including it cut hamstring injuries by up to 51% (risk ratio 0.49). A 2015 randomized trial in amateur soccer players lowered the injury rate but not injury severity. A 2021 reappraisal found only five of those 15 studies were randomized to it and called the preventive effect inconclusive (risk ratio 0.59, wide confidence interval 0.27 to 1.29). It probably helps; it is not settled.
Second, agility and trunk stability work. The 2023 meta-analysis found it significantly lowered reinjury at 12 months, while lengthening loads shortened return time without preventing recurrence. So the safest plan is both: lengthening strength first, then running, change-of-direction and trunk work before sport.
What do PRP, laser, shockwave and compression show for a hamstring strain?
For an acute strain, rehab exercise is the proven treatment, and none of these add-ons has shown a clear, consistent benefit on top of it. Here is each at its exact strength.
PRP (platelet-rich plasma). A doctor's injection that the studio does not offer. A 2015 meta-analysis of three studies found no effect (hazard ratio 1.03), and a 2015 trial of 90 professional athletes found no benefit over intensive rehab. A 2026 meta-analysis of six trials (277 people) found return about 8.6 days sooner, with very high variation between trials, unchanged reinjury, and low to moderate certainty. Our PRP guide covers aftercare.
Laser. One randomized trial in 22 amateur athletes found low-level laser added to rehab made no difference: 23 versus 24 days to return. That tested low-level laser; the higher-intensity Class IV laser was a different device. A 2026 scoping review listed laser among approaches found only in secondary sources, mostly narrative reviews, and said their effectiveness was not always supported. See our laser guide.
Shockwave. No trial in acute hamstring strain turned up in this review of the literature. The one randomized trial found studied a different problem, chronic tendon pain near the sitting bone, in 40 professional athletes: at three months, 17 of 20 had at least half their pain gone with shockwave versus 2 of 20 on conventional care. It was published in 2010 and does not show shockwave helps a fresh pull.
Compression. PEACE and LOVE supports bandages or tape in the first days and notes conflicting studies. No randomized trial of compression devices for an acute hamstring strain turned up in the sources reviewed here. Our compression boots guide explains what the evidence covers.
The 2023 meta-analysis of therapeutic exercise concluded the effect of physical modalities alone could not be determined, because evidence was limited.
Where do studio services fit?
Studio services are an add-on around rehab, never a replacement for it or for a diagnosis. OutFlex is built for hamstring, quad and calf strains and bundles PEMF, Class IV laser and red light, with your clinician setting each visit. For a moderate strain, or one that keeps coming back, OutRebuild is a fuller program listed as working alongside physical therapy. Once you are cleared and training, OutTrain bundles recovery sessions, including Normatec compression, for runners and tennis or pickleball players.
Be clear about what the evidence supports. This guide cites no hamstring-specific trial for PEMF or red light, and the laser and shockwave evidence above is limited or about other conditions, so treat them as comfort and routine rather than as a way to speed the muscle. Read the studio's research summaries for laser, PEMF and shockwave. A calf strain is similar but not identical; see our calf strain guide. Playing pickleball? See pickleball injuries.
What should you do next?
Use this rule. If you have the avulsion signs above, see an orthopedic surgeon this week. If not, see a physical therapist or sports medicine doctor within a few days, since progressive loading is the part that works. Bring these questions:
- Which grade do you think this is, and do I need imaging?
- When do I start strengthening, and how much pain is acceptable?
- Which test clears me to run, and then to play?
- Is anything on my list, including ice, anti-inflammatories or add-on therapies, worth using?
If you want add-ons alongside your plan, call the studio at 675 Piper Boulevard in North Naples and share your clinician's plan first. Check anything new with your surgeon if you had surgery.
Sources
- American Academy of Orthopaedic Surgeons. Hamstring Muscle Injuries. OrthoInfo, reviewed 2025. https://orthoinfo.aaos.org/en/diseases--conditions/hamstring-muscle-injuries/
- StatPearls. Anatomy, Bony Pelvis and Lower Limb, Hamstring Muscle. NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/sites/books/NBK546688
- Yetter TR, et al. Management of Proximal Hamstring Injuries: Non-operative and Operative Treatment. Current Reviews in Musculoskeletal Medicine, 2024. https://pmc.ncbi.nlm.nih.gov/articles/PMC11335994
- Rudisill SS, et al. Evidence-Based Management and Factors Associated With Return to Play After Acute Hamstring Injury in Athletes: A Systematic Review. Orthopaedic Journal of Sports Medicine, 2021. https://pmc.ncbi.nlm.nih.gov/articles/PMC8649106
- Case report: Two patients with a complete proximal rupture of the hamstring. PubMed Central. https://pmc.ncbi.nlm.nih.gov/articles/PMC2826630
- Dubois B, Esculier JF. Soft-tissue injuries simply need PEACE and LOVE. British Journal of Sports Medicine, 2020. https://pubmed.ncbi.nlm.nih.gov/31377722
- Ekstrand J, et al. Hamstring muscle injuries in professional football: the correlation of MRI findings with return to play. British Journal of Sports Medicine, 2012. https://pubmed.ncbi.nlm.nih.gov/22144005
- Askling CM, Tengvar M, Thorstensson A. Acute hamstring injuries in Swedish elite football: a prospective randomised controlled clinical trial comparing two rehabilitation protocols. British Journal of Sports Medicine, 2013. https://pubmed.ncbi.nlm.nih.gov/23536466/
- Askling CM, et al. Acute hamstring injuries in Swedish elite sprinters and jumpers: a prospective randomised controlled clinical trial comparing two rehabilitation protocols. British Journal of Sports Medicine, 2014. https://pubmed.ncbi.nlm.nih.gov/24620041/
- Pas HI, 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. British Journal of Sports Medicine, 2015. https://pubmed.ncbi.nlm.nih.gov/26198389
- Jankaew A, et al. Therapeutic Exercises and Modalities in Athletes With Acute Hamstring Injuries: A Systematic Review and Meta-analysis. Sports Health, 2023. https://pubmed.ncbi.nlm.nih.gov/35996322
- Hickey JT, et al. Pain-Free Versus Pain-Threshold Rehabilitation Following Acute Hamstring Strain Injury: A Randomized Controlled Trial. Journal of Orthopaedic and Sports Physical Therapy, 2020. https://pubmed.ncbi.nlm.nih.gov/32005093
- Hickey JT, et al. Early introduction of high-intensity eccentric loading into hamstring strain injury rehabilitation. Journal of Science and Medicine in Sport, 2022. https://pubmed.ncbi.nlm.nih.gov/35794049
- Ishøi L, et al. Diagnosis, prevention and treatment of common lower extremity muscle injuries in sport: grading the evidence (Danish Society of Sports Physical Therapy statement). British Journal of Sports Medicine, 2020. https://pmc.ncbi.nlm.nih.gov/articles/PMC7212929
- Silder A, et al. Clinical and morphological changes following 2 rehabilitation programs for acute hamstring strain injuries: a randomized clinical trial. Journal of Orthopaedic and Sports Physical Therapy, 2013. https://pubmed.ncbi.nlm.nih.gov/23485730
- van Dyk N, Behan FP, Whiteley R. Including the Nordic hamstring exercise in injury prevention programmes halves the rate of hamstring injuries: a systematic review and meta-analysis of 8459 athletes. British Journal of Sports Medicine, 2019. https://pubmed.ncbi.nlm.nih.gov/30808663
- van der Horst N, et al. The preventive effect of the Nordic hamstring exercise on hamstring injuries in amateur soccer players: a randomized controlled trial. American Journal of Sports Medicine, 2015. https://pubmed.ncbi.nlm.nih.gov/25794868
- Why methods matter in a meta-analysis: a reappraisal showed inconclusive injury preventive effect of Nordic hamstring exercise. 2021. https://pubmed.ncbi.nlm.nih.gov/34520846
- Hamilton B, et al. Platelet-rich plasma does not enhance return to play in hamstring injuries: a randomised controlled trial. British Journal of Sports Medicine, 2015. https://pubmed.ncbi.nlm.nih.gov/26136179
- Nakagawa H, et al. Effects of percutaneous platelet-rich plasma injection on return-to-play after acute hamstring muscle injury: a systematic review and meta-analysis. British Journal of Sports Medicine, 2026. https://pubmed.ncbi.nlm.nih.gov/41708276
- Medeiros DM, et al. Effects of low-level laser therapy on hamstring strain injury rehabilitation: a randomized controlled trial. Physical Therapy in Sport, 2020. https://pubmed.ncbi.nlm.nih.gov/31991284
- Cadellans-Arróniz A, et al. Hamstring muscle injury rehabilitation in sports: a scoping review. BMJ Open Sport and Exercise Medicine, 2026. https://pmc.ncbi.nlm.nih.gov/articles/PMC13536156
- Cacchio A, et al. Shockwave therapy for the treatment of chronic proximal hamstring tendinopathy in professional athletes. American Journal of Sports Medicine, 2010. https://pubmed.ncbi.nlm.nih.gov/20855554
