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It's About Time

It's About Time

Exercise, it’s About Time, time under tension (TUT) that is.  If you lift weights you’ve most likely heard this term at some point along your journey. Good chance it was mentioned in a conversation, media piece or Google search related to recommendations for increasing muscle mass.   “They,” the collective voice of conventional wisdom on exercise, often propose that increasing TUT is a necessary step for building hypertrophy.  But...what are they talking about, exactly?  The amount of time it takes to complete a single rep?  The amount of time it takes to complete a set?  The amount of time a muscle is exposed to tension during an entire workout?  All the above?  

Is increased time under tension a magical elixir for all muscular development concerns, including making gains in strength and power?  Could it be that increasing TUT might actually inhibit the development of certain substrates!?  Are there some lesser known applications you can try in the gym tomorrow that might just yield better results?  Well, It’s About Time someone turned a critical eye towards this topic to separate the supported from the supposed, and that is exactly what we do in It’s About Time, this week’s installment of the Fitness For Consumption podcast.

Three reasons why you should listen to this episode:

  1. The conventional wisdom of time under tension.  TUT, either by increasing the length of a single rep, or increasing the amount of reps in a set to fatigue is often considered a requisite for developing hypertrophy.  It’s also speculated by some that training slowly is a safer and more effective way of training for explosive power.  The research in this area can paint a different picture however, and it might just make you reconsider what you have heard.
  2. A (not) new way of thinking about your sets: cluster loading.  Although cluster loading has been around for decades, it is unfortunately not well known within the consumer and even fitness professional population.  What is it?  Why use it?  How might it be used as a potentially ideal application for traversing the challenge of developing strength, power and hypertrophy?  What are some potential drawbacks?  We cover the research and share some really interesting findings.
  3. On a neuromotor level, what actually happens when you move slowly and intend to move slowly?  With so many social media fitness accounts seemingly obsessed with creating muscle activation, what does some of the research investigating deliberately slow and fatiguing movement actually show us about recruiting fast twitch motor units?  And, what, if anything, can you do about it using voluntary intention?  

Think learning about any of this can help you in your workouts? We do! Only one way to find out though, give it a listen and let us know what you think!

In this episode we discuss:

  • The different perspectives on TUT
  • EMG studies examining effects of sustained muscular contraction
  • What happens to our ability to recruit fast twitch motor units during fatiguing contractions
  • Cluster loading principles and potential applications
  • Are sports binary in function?  Either totally aerobic or anaerobic?  What to consider if you need both


Cluster Loading - An alternative form of performing an exercise set in which  there are distinct  rest intervals between either single repetitions or   a few grouped repetitions, for the purpose of preserving power output

Isokinetic Exercise -  Exercise performed at constant speed

Isometric Exercise - Exercise performed where there is muscular contraction but no joint displacement

Isotonic Exercise - Exercise performed with a constant load

Presynaptic Facilitation - A process whereby motor units are stimulated, lowering their firing threshold and facilitating an action potential.

Presynaptic  Inhibition - A process in which a nerve cell is inhibited, raising the firing threshold  and decreasing the likelihood of reaching an action potential.

Supraspinal Centers - Supraspinal/segmental centers are centers "above" the spinal cord and brainstem including cerebellum, basal ganglia and the sensory and motor cortices cortexes


  1. Christensen, H. and Fuglsang-Frederiksen, A. (1988). Quantitative surface EMG during sustained and intermittent submaximal contractions. Electroencephalography and Clinical Neurophysiology. 70: 239-247.
  2. Davies, T.B., Halaki, M., Orr, R., et al (2020). Changes in bench press velocity and power after 8 weeks of high-load cluster- or traditional-set structures. Journal of Strength and Conditioning Research. 34(10): 2734-2742.
  3. Faigenbaum, A. D., Kraemer, W. J., Blimkie, C. J., Jeffreys, I., Micheli, L. J., Nitka, M., & Rowland, T. W. (2009). Youth resistance training: updated position statement paper from the national strength and conditioning association. Journal of strength and conditioning research, 23(5 Suppl), S60–S79.
  4. Fuglevand, A.J., Zackowski, K.M., Huey, K.A. and Enoka, R.M. (1993). Impairment of neuromuscular propagation during human fatiguing contractions at submaximal forces. Journal of Physiology. 460: 549-572.
  5. Garcia-Ramos, A., Gonzalez-Hernandez, J.M., Banos-Pelegrin, E., et al. (2020). Mechanical and metabolic responses to traditional and cluster set configurations in the bench press exercise. Journal of Strength and Conditioning Research. 34(3): 663-670.
  6. Grimby, L. and Hannerz, J. (1977). Firing rate and recruitment order of toe extensor motor units in different modes of voluntary contraction. Journal of Physiology. 264: 865-879.
  7. Hannerz, J. (1974). Discharge properties of motor units in relation to recruitment order in voluntary contractions. Acta Phsysiologica Scandinavia. 91: 374-384.
  8. Hansen, K.T., Cronin, J.B., and Newton, M.J. (2011). The effect of cluster loading on force, velocity, and power during ballistic jump squat training. International Journal of Sports Physiology and Performance. 6(4): 455-468.
  9. Krogh-Lund, C. and Jorgensen, K. (1993). Myo-electric fatigue manifestations revisited: power spectrum, conduction velocity, and amplitude of human elbow flexor muscles during isolated and repetitive endurance contractions at 30% maximal voluntary contraction. European Journal of Applied Physiology. 66: 161-173.
  10. Loscher, W.N., Cresswell, A.G. and Thorstensson, A. (1996). Excitatory drive to the alpha-motoneuron pool during fatiguing submaximal contractions in man. Journal of Physiology. 491: 271-280.
  11. Moffroid, M.T. and Whipple, R.H. (1990). Specificity of speed of exercise. Journal of Orthopaedic and Sports Physical Therapy. 12(2): 72-77.
  12. Moritani, T., Nagata, A., and Muro, M. (1982). Electromyographic manifestations of muscular fatigue. Medicine and Science in Sports & Exercise. 14(3): 198-202.

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