Working in elite sports with Germany’s fastest athletes (track & field, bobsleigh and skeleton) during the last seven years taught me that training, in general, and hamstring strengthening, in particular, manifest the truth of Aristotle’s quote:
“Excellence is never an accident. It is always the result of high intention, sincere effort, and intelligent execution; it represents the wise choice of many alternatives – choice, not chance, determines your destiny.”
Every athlete who executes acceleration or high speed sprints needs strong and powerful hamstring muscles [3, 9], as the risk of a muscle strain or tear is always present. Practitioners and scientists know that there is a multifactorial interaction of risk factors.
Day after day, lots of isokinetic tests assess a “strength deficit” of the hamstrings. Even with more advanced and more frequent diagnostic tests on this particular area, the injury incidences (e.g., in elite soccer players) are still rising [8].
A popular choice to strengthen the “weak hammies” is the Nordic hamstring exercise (NHE), which selectively activates the hamstrings via high eccentric loading and effectively reduces the hamstring strain injury incidence by a considerable 51% [10]. However, the exercise has several disadvantages that limit compliance and acceptance, and, therefore, implementation:
- knee pain when kneeling on a rigid, uncushioned surface;
- supramaximal loading causes delayed onset muscular soreness, which impairs subsequent training sessions and potentially elevates the injury risk;
- high time under tension in knee angles that are not specific to the mechanisms of injury, specifically 90° to 60° knee flexion preferentially activating the semitendinosus.
Overcoming the temptation of “Nordic flopping”
Aristotle’s quote is particularly apt when we consider that the usual execution of the NHE looks more like an accidental eccentric chest exercise rather than an intentional, purposeful movement benefiting the hamstrings. This “Nordic flopping” is characterised by a short – sometimes negligible – active and controlled range of motion through the hamstrings (~30°), with the hands at chest level doing the “hard work” of braking the high velocity at the end of the exercise [6].
To be effective for targeted injury prevention, rehabilitation and performance enhancement, the NHE requires:
- High intention: repeated microdosed stimuli targeting specific neuromuscular and tendinous adaptations
- Sincere effort: high muscle activation at extended knee angles that preferentially target the injury prone biceps femoris;
- Intelligent execution: proper setup, guided or assisted execution, variation of shank inclination, hip angle configuration and hip extensor activation.
The following sections aggregate my best practice guidelines from my experience with World and Olympic champions as well as medallists at World and European Youth Championships.
Proper set up for the Nordic hamstring exercise
High quality execution of the Nordic hamstring exercise and related variations should guarantee rigid resistance at the heels, free knee caps to ensure patellar glide, and sufficient kneeling height so the athlete can reach extended knee angles [5].
If a fixed resistance cannot be provided, athletes cannot reach extended knee angles at the highest intensity, i.e., the highest force generation. Those angles are critical for both performance and injury prevention.
Realistically, practitioners cannot always guarantee all of the ideal conditions, particularly in team sports settings where a larger cohort of athletes are training simultaneously. Table 1 lists reasonable and acceptable deviations for those scenarios.
| Setup modality | Optimal | Acceptable | Limitations |
| Fixed resistance | Stationary/fixed horizontal object able to withstand 2x body mass | Partner holds the heels, NOT the calves or Achilles tendon | Reduced knee range of motion (due to insufficient abutment), impaired reproducibility and reduced peak load |
| Free knee caps | Tibial tuberosity on edge of surface, knees do not touch the ground | Knees are on a cushioned surface (e.g. balance pad, towel roll) | Lower comfort and peak load |
| Kneeling height | Shanks are at least 15cm above the floor to enable full knee extension | Knees do not touch the ground | Limited range of motion during hip flexion |
The razor curl is an example of an acceptable setup modification for a team training context. A partner holds the athlete’s heels, the knee caps are free via a rolled mat, and the knees do not touch the ground. Due to the guidance with the hands, the athlete can maintain a high muscle activity across the entire range of motion. Since the partner fixation is lower than 2x body mass, it does not suffice to provide a rigid abutment in Nordic hamstring plank position (full knee and hip extension).
If practitioners want the athletes to perform the exercises with hip flexion, a higher kneeling height or an inclination of the shank are essential (Figure 1B, D). From my experience, an abutment at the heels enables the highest possible force generation. An abutment at the calves or at the Achilles tendon is uncomfortable due to soft tissue compression, as a higher force is needed to counterbalance the shorter lever arm. That is particularly the situation at higher intensities.
Execution quality
The progression of hamstring exercises should always focus on intensity as well as variation, and not on volume. Unfortunately, many research papers and practical guidelines recommend progressing the number of reps.
A reasonable volume of the standard NHE for general strengthening purposes is 2-3 sets of three repetitions [1].
To attain the best transfer to acceleration and high speed sprints, the ankles are in a neutral or slightly dorsiflexed position (Figure 1). The major focus and the ultimate training goal are achieving the highest possible activation of the hamstrings across the entire range of motion. Movement velocity should be low: 5-7 seconds for an NHE across 90° knee flexion. That allows the muscles to generate a high force potential, which stimulates tendon stretch and subsequent adaptations [7]. Consequently, muscle fatigue should be kept as low as possible. This constraint keeps the number of reps per set low (<5), except for submaximal repetitions (e.g., at 80% of the maximum voluntary activation level) or regressed exercises.
Always keep in mind that during a 90° ROM NHE, 70% of the generated impulse occurs in the second half of the movement, from 45° to 0° of knee flexion.
Consequently, it is crucially important to dive deep into these extended knee angles. The key point for coaches is to ensure that muscle activity remains high throughout the entire range of motion. This entails good execution quality, so coaches must particularly watch that the athlete does not arch the lower back arch during the standard NHE. This is a common outcome if the athlete is overwhelmed by the external load, which inevitably increases the movement velocity.
Tweet ThisThe progression of hamstring exercises should always focus on intensity as well as variation, and not on volume
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Regressing the Nordic hamstring exercise
Unfortunately, knowledge of the many variations of the standard NHE is quite limited [4]. Given that these variations each promote specific adaptations, this widespread lack of understanding limits the athletes’ progressions. On the other hand, practitioners should be aware of the “wise choice of many alternatives.” Selecting the “correct” variation for a given athlete is a mixture of 80% brain and evidence, and 20% experience and feeling.
Most athletes do not possess the strength capacities to execute an NHE across the full range of motion; and they usually experience a consistent overload without improvement over time, despite continuous training.
Therefore, providing assistance or hands-on guidance are appropriate tools.
For assistance, I am not a big supporter of elastic bands. While they are suitable and straightforward for beginners, the support they provide at the end of the movement (20° to 0° knee flexion) is too high for ambitious athletes. Having a partner support the athletes at the shoulders is a better alternative.
Athletes can guide their movements by using their hands to support themselves just as much as necessary to maintain the highest muscle activation and control.
Within the end range of the exercise, the athlete possesses a higher force potential due to the exponentially increasing contribution of tendons and passive elements. Partner support at the shoulders or self-guidance can be adapted to the actual amount of assistance needed, with the curve of this relationship resembling an inverted U.
Guiding the movement allows athletes to perform various forms of warm up and pre-activation exercises at dosed intensities (Figure 2). Along with assistance and guidance, we can organize regression and specific stimuli by: lower coordinative demands (isometric exercises), shank inclination, and hip flexion.
The Nordic hamstring push up (Video 2), for example, elicits the highest biceps femoris activity if isometric hip extension (glute squeeze) is added at the end of the movement (knee and hip go into full extension as the athlete approaching the NH plank) [4]. Video 2 shows a remarkable muscle tremor at the end of each repetition, which emphasizes the demand and effectiveness of the exercise despite appearing superficially simple.
Tweet ThisIsometric and guided exercises are easy to perform and can be executed by everyone, thus are ideal for beginners or weaker individuals, or in rehabilitative contexts
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End game: Strength at long muscle-tendon lengths
All training should prepare athletes for the worst case scenarios, where, under controlled conditions, they confront an extreme range of motion (Video 3) or a severe loading (Video 4). This is especially apt for hamstring training. Nevertheless, we should always keep in mind that the goal of sports specific training is optimization, not maximization. Instagram videos showing exceptional NHE performance or other related exercises fascinate people, but there will always be a certain threshold at which an athlete is strong enough for a certain task (Video 5).
The pike position in Video 3 (with 36° shank inclination) elongates the entire posterior fascia chain and is therefore optimal for warm-up or cool-down.
The decelerated Nordic hamstring exercise (Video 4) imposes a severe loading and strain rate on the muscle-tendon units. The generated eccentric knee moment is ~20% higher than the standard NHE [4]. Consequently, its should only be performed by strong and experienced individuals.
Video 5 shows a random selection of severe Nordic hamstring and razor curl exercise variants. Note the complete, intentional absence of the concentric phase of NHEs. In its place, I prefer the concentric razor curl because it replicates the actual sports-specific movement patterns much better: reactive knee and hip flexion after explosive extension.
In this exercise sequence, I just played around to see what my body is capable of. In training, I would never conduct seven repetitions (plus four bouncing Nordic hamstring planks at the very end) in a row due to excessive muscle fatigue.
Two exercises that are great for assessing hamstring strength (capacity) thresholds are the Nordic hamstring plank (intermediate muscle-tendon length), and the final position of knee and hip dominant diver (long muscle-tendon length).
Athletes should perform both exercises with rigid heel fixation and free knee caps.
If an athlete can execute these two exercises in full knee extension without guidance from the hands, the athlete is both strong and flexible. Research demonstrated that the NH plank matches the magnitude of peak moment athletes experience during maximal velocity sprints of 10 m/s, thus providing a simple benchmark. If these capacities are present, the challenge is to effectively transfer them into a sports-specific movement like initial acceleration or maximum velocity sprints.
In this context, one major point of criticism concerning the standard NHE is its extended hip position and knee dominance, which neither mirror sports-specific movement patterns nor actual injury situations. In those contexts, the hip is flexed while the knee is extending, which elongates the muscle-tendon units of the bilateral hamstrings. Coaches can straightforwardly implement those exercises as well, especially if we bear in mind that hip flexion largely affects the peak load and muscle activity of hamstring exercises (Figure 3).
The guided knee dominant diver (Video 3, Figure 2) and loaded inclined bent NHE (Videos 7 and 8) both feature flexed hip joints, and have the potential to replace the standard version of the NHE. They are more closely related to the injury scenario and demonstrate a more direct transfer to sports specific performance such as acceleration or high speed sprints.
Coaches observing the knee dominant diver must ensure an erect lower back, instructing the athletes as necessary to activate towards an anterior pelvic tilt to achieve the longest possible muscle-tendon length. If a posterior pelvic tilt occurs, reduce hip flexion (e.g., 60° instead of 90°).
The inclined bent Nordic hamstring exercise is more specific than a standard NHE and transfers better to injury scenarios and sports specific performance. If fatigue occurs, the athletes can guide themselves with the hands to the needed extent.
If regularly executed, these two exercises empower athletes to increase their force at long muscle-tendon lengths and to become robust in tolerating high loads, high ranges of motion and, after subsequent adaptations, high movement velocity or stretch. They elicit high tendon stretch and promote high muscle activation and stiffness at long muscle-tendon unit lengths [7].
To prepare athletes to quickly activate the muscles and to absorb and recoil energy in cyclic movements, reactive bounces across small ROM and flexed hips are suitable (Video 9). Reactive bounces are a nice exercise variant to prepare for fast muscle activation and energy absorption at different knee joint angles. Make sure that the athlete’s strength suffices to brake the “fall.” If you are not sure, provide guidance with the hands for higher training safety.
Finally, bent hamstring exercises – those with flexed hip joints – are great to educate athletes to create and maintain an anterior pelvic tilt, which is the longest possible muscle-tendon length. Most athletes are forced into a posterior pelvic tilt because they do not possess the capacities to flex their hip and control a neutral pelvis position. That is most identifiable during the knee and hip dominant diver (Figure 2). This lack of pelvis control at long hamstring muscle-tendon lengths likely makes them prone to injury.
The two diver exercises can be performed in various intensities (e.g., 30-50-70% as warm up), and therefore replace traditional isometric hamstring stretching exercises from a training routine. If performed at submaximal intensities, a maximum of six repetitions per set are feasible.
The three exercises in Table 2 have produced the best results for each purpose that I’ve programmed them.
| Purpose | Exercise (→ focus) |
| Warm up | Knee dominant driver (guided) → maintain an erect lower back, activate towards an anterior pelvic tilt |
| Biceps femoris activation | Guided razor curl or guided Nordic hamstring push up → superimpose isometric hip extension (glute squeeze) at the end of the movement |
| Strength | (Loaded) inclined bent Nordic hamstring exercise → skip flexed knee angles by adding shank inclination → 3 sets of 3 repetitions, 5-7s time under tension per rep |
For best possible transfer to sports-specific movements, hamstring activation should be transferred into unilateral exercises addressing similar joint angle configurations, like reaching the highest possible thigh separation for initial acceleration. The low box knee split lowers are ideal for this purpose and can be executed at various intensities.
Tweet ThisThe inclined bent Nordic hamstring exercise is more specific than a standard NHE and transfers better to injury scenarios and sports specific performance
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Working towards Nordic hamstring exercise mastery
Hamstring training should neither resemble an accident nor an eccentric chest exercise, the dreaded “Nordic flopping.” Effective hamstring training requires high intention, sincere effort and intelligent execution.
The scientific research is unclear over whether we actually need a supramaximal stimulus during hamstring exercises or if a high, sustained muscle activation with hip and knee joint configurations specific to injury prevention and sport performance will lead to more favourable adaptations [2].
My practical experience tells me that athletes greatly benefit from implementing guided and bent (flexed hip) hamstring exercise variations. We program other hamstring exercises like the single leg deadlift or Roman chair exercises, as well, but more from a holistic approach and not from a specific one. These aren’t the exercises we select to activate the biceps femoris or induce tendon adaptation, for example.
Remember your Aristotle and adhere to the principle that “choice, not chance, determines your (hamstrings’) destiny.”
If you have further or more specific questions (e.g., exercise programming and periodisation), feel free to contact me via tobias.alt@osp-westfalen.de.
