Hamstring injuries continue to be the most common injury in football, as well as in most field-based running sports and athletics. The UEFA Elite Club Injury Study suggests that they are not going away anytime soon. While the report indicates that the burden of injury has significantly decreased over the past two decades, hamstring injuries have risen from 12% of all injuries to 24%.[1]
When a player suffers an injury, our rehabilitation goals continue to be the same as always: return the athlete to sport as soon as possible, able to achieve the highest level of performance, while minimising the risk of re-injury.
Figure 1. Proportion of hamstring injuries from the UEFA Elite Club Injury Study. Top panel is hamstring injury as percentage of total injuries; bottom panel shows days lost to hamstring injury as percentage of total days lost to injury.[1]
Tweet ThisHamstring injuries are the most common in football and field-based sports, rising from 12% to 24% of all injuries over two decades. Our goal remains to return athletes to sport quickly, performing at their best while minimizing re-injury risk.
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Three key goals for rehab are reducing pain and enhancing tissue healing; improving and expanding tissue capacity; and incorporating and developing movement capability.
While we don’t approach these goals in series (e.g., we might aim for tissue capacity and enhanced tissue healing simultaneously), viewing the progression in that order makes it easier to determine your loading strategy. After all, “rehab is training in the presence of injury.” – Phil Glasgow. That is why we need to know what we are paying attention to during rehabilitation. What clues, signs or clinical data can help me better understand how to progress during rehabilitation of a muscle injury?
Important to this process are objective measurements that are reliable and delivered in an easy-to-use manner. Measurement tools to assess range of motion and strength are continuously evolving. New innovations like VALD’s Dynamo and real-time integration with VALDHUB allow for immediate feedback, accurate measurement and repeatability, and comparison with previous measurements.
At the Aspetar Orthopaedic and Sports Medicine Hospital, we investigated our daily clinical assessments, and explored how these data can help us to better understand our progress during rehabilitation. While we had a look at almost everything we do, we learned what to pay attention to, and how this might be interpreted for exercise prescription when building a rehab programme.[2]
Tweet ThisRehab goals for hamstring injuries: reduce pain, enhance tissue healing, improve tissue capacity, and develop movement capability. ‘Rehab is training in the presence of injury’ – Phil Glasgow. Understanding these stages helps in effective rehab.
@nicolvandyk
Reducing pain and enhancing tissue healing
We can be more forgiving to muscle injuries and allow some pain during rehab, even early on.3 But pain is still a useful indicator to help your clinical decision making.
Pain tends to normalize quickly by day 4 or 5 (Figure 2). If it doesn’t, that already tells you something of the pain experience the person is going through.
Once it has settled, if you see a change in pain during rehab, pay attention. It usually indicates a response to load, and if pain gets worse (whether it’s specific or general), consider taking a step back and wait for pain levels to settle before continuing to progress.
(Top tip – think about these changes as both in-session and between-sessions changes. Sometimes waiting a few minutes within a session is enough, and other times you need a longer rest period.)
Overall, this is a good sign, especially if the person relates it to a general feeling of achiness. It means we are starting to hit our stride in rehab, and the exercises are of a sufficient load. But we want to be mindful of the healing process and give the person enough time to recover from the stimulus we’re providing. Apart from a numeric rating scale or visual analogue scale, consider simply asking: “Are you better, worse, or the same?”
Figure 2. Correlation between pain (visual analogue scale 1 – 10) and return to sport (days). If pain worsens (reported or on palpation), take a step back.[2]
Some of the most useful measures of pain come from palpation. The “length” of pain the person experiences on palpation is measured in centimetres. Remember to palpate laterally and vertically to ensure you are covering the area well; but make the measurement as a straight line.
Tweet ThisDuring hamstring rehab, the length of pain experienced on palpation can be a useful measure. When the pain length reduces to one-third of the initial assessment, you’re halfway through rehab. This is a good clinical sign to track progress.
@nicolvandyk
When the length of pain is one third of the initial assessment, you should be halfway through your rehabilitation. For example, if you initially measured 10 cm of pain and on day 11 it’s at 3 cm, you have about 10 days left. This is not a hard rule, and Figure 3 shows that large confidence intervals exist. Not everyone will make progress in this clear way, but the data suggest it is a good clinical sign to pay attention to.
Figure 3. Association between pain on palpation (as percentage of initial length in cm) and return to sport (days).[2]
| Exercise | Sets and reps | Rest | What to look for |
| Free active movement | 3 x 15 | 30s | Pain free range of motion |
| Bridge (double leg) | 3 x 12 | 30s | Single leg if double leg pain free |
| Heel slides in supine | 3 x 8 | 30s | Pain free, can be assisted early on |
| Heel digs in supine (inner / mid / outer range) | 3 x 12 | 30 – 90 s | Some pain allowed |
| Isometric contractions | 3 x 12 | 10 – 15 s | |
| Manual resisted isometrics | 3 x 12 | 10 – 15 s | Different range of movement |
| Double leg squat | 3 x 8 | 30 s | Criteria for progression |
| Singe leg squat | 3 x 6 | 30 s | Criteria for progression |
| Stationary bike | 5-10min, 80RPM | Criteria for progression | |
| Asking lengthening exercises: | |||
| Extender | 3 x 12 (repeat) | 10 – 15 s | Quality is key, use resistance band to facilitate medium velocity. |
| Diver | 3 x 6 | 10 – 15 s | |
| Glider | 3 x 6 | 10 – 15 s | |
| Trunk mobility exercises | As appropriate | If indicated in assessment | |
| Lumbo-pelvic control | As appropriate | Incorporate in session when doing other exercises. If necessary, isolate. |
Improving and expanding tissue capacity
Where the desired adaptations are changes to muscle architecture, such as increased fascicle length, the intervention may be eccentric loading and the progression will include adding load, increasing speed, and expanding range of motion. In contrast, where the focus is increasing rate of force development, the exercise may be a jump squat, with progressions involving weight, resistance, or difficulty in task execution.
Early on, we are aiming for hypertrophy (three sets of 8 – 12 reps). Mid to late stages, we’re aiming for strength or even power (three sets of 6 – 8 reps with greater rest periods).
A big limitation for most practitioners is time, since we want enough recovery between sets. This is where independence and the player taking ownership of the process are important. Technology can play an important role in terms of remote monitoring and support.
Range of motion / muscle length
We can measure range of motion during hamstring rehab via the passive knee extension test, the active knee extension test, and the straight leg raise (active and passive). But the maximal hip flexion active knee extension test gets the most out of the lengthening assessments. It normalizes about halfway through the recovery process (Figure 4). After that, we return to it to monitor response to treatment and aid the clinical decision making and reasoning for progression during rehab. Pay attention when it suddenly worsens in response to training load.
Figure 4. Association between maximal hip flexion active knee extension test (MHFAKE) as a percentage of initial assessment in degrees with completion of rehabilitation.[2]
Muscle strength
Different strength assessments are available, but inner, mid, and outer range strength continue to be the main assessments. For hamstring injuries, our go-to inner range assessment is a hand-held dynamometer test. It normalizes quite soon after rehab starts, and therefore offers little assistance in progression planning. Outer range tests are much more effective for monitoring progress (Figure 5).
Figure 5. Association between outer range strength (as a percentage of the initial assessment measured in kg) and completion of rehabilitation.[2]
Any of the early exercises can still be included, either as preparation for the session or to facilitate specific loading goals.
| Exercise / drill | Sets and reps | Rest | What to look for |
| Ham slides (bilateral to unilateral) | 3 x 8 | Pain | |
| Bridge on step | 3 x 6 | Movement control | |
| Glut ham raise (with weight) | 3 x 8 | 1 – 3 min | Technique |
| Hip extension exercise (with weight) | 3 x 8 | 1 – 3 min | Technique |
| Double leg squat (with weight) | 3 x 8 | 30 – 90 s | Pain |
| Singe leg squat | 3 x 6 | 30 – 90 s | Pain |
| Stationary bike | 5-10 min, 80RPM | Warm up to running | |
| Askling lengthening exercises: (as home exercise/warm up) | |||
| Extender | 3 x 12 (repeat) | Quality is key, use resistance band to facilitate, medium velocity. | |
| Diver | 3 x 6 | ||
| Glider | 3 x 6 | ||
| Trunk mobility exercises | As appropriate | 10 – 15 s | Incorporate in session when doing other exercises. If necessary, isolate. |
| Lumbo-pelvic control | As appropriate | 10 – 15 s | |
| Running (approx. 700m in total) | |||
| A-drills | 3 x 4 | 2 – 3 min | 4 sets, with 2 x 25-30m straight line running in each set. Observe form and function, start 10-20% of max and progress (no more than 10% in a session) |
| Triple hops | 3 x 4 | 2 – 3 min | |
| Self-paced running (50-70%) | 3 x 4 | 2 – 3 min |
Incorporating and developing movement capability
An important transition takes place as the rehabilitation process moves towards movement capability: movement variability creates adaptation that is important for performance, sometimes referred to as “repetition without repetition” (Bernstein 1920). We ramp up movement capability as we progress to the mid and late stages of the rehab programme, adding more ballistic and plyometric components, adding reactive exercise routines, and challenging players in terms of fatigue and sport specific drills.[4]
Tweet ThisIncorporating movement variability in mid to late rehab stages is crucial. Adding ballistic, plyometric components and sport-specific drills challenges players, enhances adaptation, and prepares them for the demands of their sport.
@nicolvandyk
Throughout the rehab, the player “earns the right” to progress, and we are satisfied with the exposure and input at each of these stages. Notice here the inclusion of Nordic hamstring exercises (Figure 6). Some players may move into this phase relatively soon, and we urge clinicians to continue to clinically reason about these progressions. We certainly have good evidence that we can introduce Nordics (read eccentric overload) early.
Pragmatically, a player can’t increase their load / intensity by more than 10% from one session to the next, especially if they are rehabbing independently. It’s also important to understand a player’s response, and their approach to the process. A clinical sign for caution is when a player starts to complain of the muscle “stiffening up” during rehab. Take a step back and reassess before progressing.
We compared our clinical assessments to a performance test: how did the strength and length of the muscle correlate to self-reported running (a percentage of their perceived maximum running speed)?
It turns out the maximal hip flexion active knee extension test was a bust, but outer range strength was reasonably well correlated with running speed (Figure 6). If a player is at 50% of their uninjured / baseline strength test, they should be able to run at 50% of their maximum speed. We must heed the confidence intervals and remember that this won’t work for every player. But as a rough guide, it works well.
Figure 7. Association between outer range strength (as a percentage of the initial assessment) and running effort.[2]
Any of the early and mid-stage rehab exercises can still be included, either as preparation for the session or to facilitate specific loading goals.
| Exercise / drill | Sets and reps | Rest | What to look for |
| Bridge on step | 3 x 6 | Movement control | |
| Hip extension exercise (with weight) | 3 x 8 | 1 – 3 min | Technique |
| Double leg squat (Smith Machine) | 3 x 8 | 1 – 3 min | Control and moving towards 70% RPM |
| Singe leg squat (Goblet or free) | 3 x 6 | 1 – 3 min | Control and moving towards 70% RPM |
| Romanian dead lifts | 3 x 6 | 1 – 3 min | Control and moving towards 70% RPM |
| Walking lunges (with weight) | 3 x 4 (5m) | 2 – 3 min | Control and moving towards 70% RPM |
| Nordic hamstring exercise | 3 x 6-8 | 2 – 3 min | 3 exposures per week |
| Plyometric sequence | 1 – 3 min | 2 min | |
| Stationary bike | 5-10min, 80RPM | Warm up to running | |
| Asking lengthening exercises: (as home exercise / warm up) | These exercises could be sandwiched between running drills as active recovery. | ||
| Extender | 3 x 12 (repeat) | Quality is key, use resistance band to facilitate, medium velocity. | |
| Diver | 3 x 6 | ||
| Glider | 3 x 6 | ||
| Trunk mobility exercises | As appropriate | Incorporate in session when doing other exercises. If necessary, isolate. | |
| Lumbo-pelvic control | As appropriate | ||
| Running (approx. 700m in total) | |||
| A-drills | 3 x 4 | 2 – 3 min | 4 sets, with 2 x 25-30m straight line running in each set. Observe form and function, start 10-20% of max and progress (no more than 10% in a session) |
| Triple hops | 3 x 4 | 2 – 3 min | |
| Self-paced running (80 – 100%) | 3 x 4 | 2 – 3min | |
| Sport specific sessions | 20 -40min | Sport specific drills now include more cognitive dual tasks, effort, fatigue, and constraint applied sport scenarios. |
When rehabilitating hamstring injuries, here are the top five tips for what matters from your (daily) reassessment:
- If pain gets worse (rated or on palpation), take a step back.
- When length of pain on palpation is one third of initial assessment, the athlete is about 50% through rehab.
- Maximal hip flexion active knee extension test is our best range of motion test, but it normalizes about halfway through recovery.
- Outer range strength is the best indicator of progress through rehabilitation.
- Correlation between outer range strength and running effort is correlated.
Having these results and data at your disposal will elevate your ability to optimize the rehab programme.
Figure 8. Intelligence based practice – Merging evidence-based practice with data insights from new technology.5
While we still focus on the main four components in our assessment and reassessment – pain, function, strength, and range of motion – objective measures and the insights they provide in combination are invaluable. Of course, you must listen to your player, be mindful of your clinical intuition (experience), and continue to incorporate evidence such as this in your clinical decision making. This is the core of evidence-based practice. Appropriate and reliable data collection will allow you to monitor and measure what you do in a meaningful way – what I like to call intelligence-based practice (Figure 7). Knowing what to pay attention to will elevate your rehab, and the outcomes for the player.
