Hamstring “Tantrums”: Effective Exercise or Social Media Noise?

In recent years, hamstring tantrums (also referred to as Swiss‑ball kicks or flutter kicks) have gained popularity, largely supported by EMG studies reporting high levels of hamstring activation during the exercise, and viral trending videos on social media. However, what's important to understand is that muscle activation alone is a poor criterion for judging the usefulness of an exercise.

If the goal is to improve performance, reduce injury risk, or drive specific tissue adaptations, we must ask more relevant questions: What adaptation does this exercise target? Under which mechanical conditions? And how transferable is it to sport?

Muscle Activation: A Weak Discriminant When Considered in Isolation

Some studies have reported high hamstring EMG activity during tantrum‑type exercises, particularly in prone or Swiss‑ball variations (Tsaklis et al., 2015).

However:

• EMG amplitude does not quantify mechanical tension or internal muscle force.

• It does not provide information about muscle length, strain, or loading distribution.

• High activation can occur under low mechanical stress, especially during concentric or short‑range tasks

  
  

This limitation of EMG as a proxy for training stimulus has been widely discussed in the literature (Vigotsky et al., 2018; Enoka and Duchateau, 2017).

High activation does not necessarily imply a meaningful adaptive stimulus.

Tissue Remodeling: Which Kind of Adaptation Can We Expect?

Structural adaptations of the hamstrings—such as increases in fascicle length, muscle‑tendon stiffness, and tolerance to high strain—are consistently associated with:

• high mechanical tension

• long muscle lengths

• and a substantial eccentric loading component

  
  

  

  Ultrasound image of the long head of the biceps femoris. SA and DA lines represent the superficial and deep aponeurosis, respectively. FL corresponds to the fascicle length of the muscle fascicle, which joins SA and DA lines and crosses the midpoint between the two aponeurosis in the center of the image. PA represents the pennation angle, which was calculated as the angle between FL and DA (from Guex et al., 2016)

Multiple studies have shown that eccentric training at long muscle lengths (e.g., Nordic

hamstring exercise) increases biceps femoris fascicle length and alters muscle architecture in a way that is considered protective (Bourne et al., 2017; Timmins et al., 2016).

Hamstring tantrums, by contrast, are:

• low external load,

• short‑range dominant,

• largely concentric in nature

From a mechanistic standpoint, their capacity to drive meaningful tissue remodeling is limited compared to long‑length eccentric exercises.

Injury Prevention: Is There a Strong Rationale?

Hamstring strain injuries most commonly occur during the late swing phase of sprinting, when the hamstrings are exposed to:

• high‑velocity lengthening

• high eccentric forces

• long muscle lengths

  
  

This mechanism has been consistently described in biomechanical and epidemiological studies (Schache et al., 2012; Chumanov et al., 2012).

Preventive interventions with the strongest evidence—such as Nordic hamstring exercise—specifically target these mechanical demands and have been shown to reduce injury incidence (van Dyk, Behan and Whiteley, 2019) as part of a comprehensive exercise program.

Tantrums, on the other hand, involve low force production, and do not meaningfully load the hamstrings eccentrically at long lengths.

Therefore, there is neither direct evidence nor a strong mechanistic rationale supporting tantrums as a primary hamstring injury‑reduction exercise.

Replicating Hamstring Function During Sprinting

During sprinting, the hamstrings act primarily to:

• eccentrically decelerate knee extension in late swing,

• contribute to hip extension under high load,

• manage rapid transitions between eccentric and concentric actions.

Biomechanical modeling studies clearly show that peak hamstring forces occur during late swing, not during stance (Schache et al., 2012).

In tantrum exercises hip position is relatively neutral, ground reaction forces are absent, and the eccentric demand is minimal.

Although movement speed may appear similar, the mechanical context is fundamentally different. Matching joint motion does not equate to matching function.

Velocity of Movement and Contraction Type

High movement velocity alone does not guarantee a high‑velocity mechanical stimulus. Force–velocity and length–tension relationships dictate that fast movements under low load produce limited mechanical stress (Lieber and Fridén, 2000).

Sprint‑specific hamstring loading involves high strain rates, high force production, and substantial eccentric work. These conditions are not replicated in tantrum‑type exercises.

Knee Joint Stabilization: Limited and Non‑Specific

Hamstrings contribute to knee joint stability, particularly by resisting anterior tibial translation. However, functional knee stabilization in sport is task‑specific and context‑dependent.

Weight‑bearing, multiplanar tasks with external perturbations are far more relevant for neuromuscular knee control than isolated, non–weight‑bearing exercises (Hewett et al., 2005).

Tantrums may provide a general, low‑level co‑contraction stimulus, but their transfer to sport‑specific knee stability is limited.

Do Hamstring Tantrums Have a Role?

In our experience, usefulness of hamstring tantrums seems to be extremely limited. If you really want to implement it, be aware of what you are intended to obtain from its use.

Prescribe tantrums as:

• a low‑load recruitment exercise in early or mid‑stage rehabilitation

• a way to reintroduce rapid knee cycling when axial loading is not yet tolerated

• an accessory exercise within a broader hamstring program

It should NOT be considered:

• a primary tissue‑remodeling stimulus

• a cornerstone injury‑prevention exercise

• or a sprint‑specific hamstring solution

Hamstring tantrums are a clear example of how EMG‑driven reasoning can overestimate exercise value. When evaluated through the lens of mechanical loading, tissue adaptation, and sport specificity, their role is accessory rather than central.

As always, exercise selection should be driven by the adaptation we seek—not by how “active” a muscle appears to be.

References

• Bourne, M. N., Williams, M. D., Opar, D. A., Al Najjar, A., Kerr, G. K. and Shield, A. J. (2017) 'Impact of exercise selection on hamstring muscle activation', British Journal of Sports Medicine, 51(13), pp. 1021-1028.

• Chumanov, E. S., Schache, A. G., Heiderscheit, B. C. and Thelen, D. G. (2012) 'Hamstrings are most susceptible to injury during the late swing phase of sprinting', British Journal of Sports Medicine, 46(2):90.

• van Dyk, N., Behan, F. P. and Whiteley, R. (2019) '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, 53(21), pp. 1362-1370.

• Enoka, R. M. and Duchateau, J. (2017) 'Rate Coding and the Control of Muscle Force', Cold Spring Harbor Perspectives in Medicine, 7(10), a029702.

• Hewett, T. E., Myer, G. D., Ford, K. R., Heidt, R. S., Colosimo, A. J., McLean, S. G., van den Bogert, A. J., Paterno, M. V. and Succop, P. (2005) 'Biomechanical measures of neuromuscular control and valgus loading of the knee predict anterior cruciate ligament injury risk in female athletes: a prospective study', The American Journal of Sports Medicine, 33(4), pp. 492-501.

• Lieber, R. L. and Friden, J. (2000) 'Functional and clinical significance of skeletal muscle architecture', Muscle & Nerve, 23(11), pp. 1647-1666.

• Schache, A. G., Dorn, T. W., Blanch, P. D., Brown, N. A. T. and Pandy, M. G. (2012) 'Mechanics of the human hamstring muscles during sprinting', Medicine and Science in Sports and Exercise, 44(4), pp. 647-658.

• Timmins, R. G., Ruddy, J. D., Presland, J., Maniar, N., Shield, A. J., Williams, M. D. and Opar, D. A. (2016) 'Architectural Changes of the Biceps Femoris Long Head after Concentric or Eccentric Training', Medicine and Science in Sports and Exercise, 48(3), pp. 499-508.

• Tsaklis, P., Malliaropoulos, N., Mendiguchia, J., Korakakis, V., Tsapralis, K., Pyne, D. and Malliaras, P. (2015) 'Muscle and intensity based hamstring exercise classification in elite female track and field athletes: implications for exercise selection during rehabilitation', Open Access Journal of Sports Medicine, 26:6:209.

• Vigotsky, A. D., Schoenfeld, B. J., Than, C. and Brown, J. M. (2018) 'Methods matter: the relationship between strength and hypertrophy depends on methods of measurement and analysis', Peer J, 6:e:5071

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Antonio Robustelli is the mastermind behind Omniathlete. He is an international high performance consultant and sought-after speaker in the area of Sport Science and Sports Medicine, working all over the world with individual athletes (including participation in the last 5 Olympics) as well as professional teams in soccer, basketball, rugby, baseball since 23 years. Currently serving as Faculty Member and Programme Leader at the National Institute of Sports in India (SAI-NSNIS).