Years and years of analysis have elapsed within the pursuit to utterly perceive the intricacies of human skeletal muscle contraction.It has included human, amphibian, and feline muscle biopsies, laboratory assessments, sensible hands-on experiments, and deductive reasoning. Thankfully, we now have a stable grip on evidence-based sensible purposes with regards to designing and implementing resistance coaching applications. However, there nonetheless exists a lot controversy, ignorance, and confusion, even amongst educated trainers and trainees on this subject.


Before I start to simplify this challenge, I perceive it could possibly grow to be an emotional subject as a result of numerous colleges of thought that exist concerning one of the best ways to get stronger, improve energy, maximize hypertrophy, enhance endurance, or enhance talent. Because there are a selection of philosophies on one of the best ways to achieve these attributes, each ego and monetary achieve are on the root of this. Hey, it’s the world we reside in, however hanging on to confirmed science and analysis will give you some solace and customary sense to maneuver ahead.



If everybody simply accepted the next three indeniable information, coaching program design and implementation can be rather more goal, safer, and smart:


  1. Activity on Earth is ruled by primary legal guidelines of physics – one being gravitational pull.
  2. The Henneman’s Size Principle of muscle fiber recruitment is the accepted gold-standard.
  3. Your genetic skeletal construction, muscle fiber endowment, and nervous system “hook-ups” can’t be ignored.


Gravity’s Pull and Resistance Training

The legislation of gravity clearly dictates you can not transfer a comparatively heavy resistance shortly. That is that if a resistance strikes shortly it should be “light” relative to your capacity. Similarly, you may transfer a lightweight resistance comparatively shortly as in comparison with “heavy” resistance. The lighter resistance is, the sooner your potential velocity of motion, all different elements being equal. Common sense, folks.


Take Olympic lifters. These individuals are robust. Look at their coaching regimens: they use coaching protocols to extend muscular power, after which apply the abilities of lifting heavy resistances with correct approach.


They can solely transfer heavy resistances so quick and so excessive, so that they want the flexibility to maneuver quick to safe it. That is, the resistance doesn’t transfer quick, however their approach does. Slower-moving entrance squatting, again squatting, and overhead urgent is finished to get stronger. Faster-moving talent apply is then carried out to excellent the required physique actions.


What a few typical train reminiscent of a bench press or leg press? It’s fairly straight-forward: load extra resistance on the bar or machine and it’ll transfer slower as in comparison with utilizing a lighter resistance relative to your capacity.


Think about it: you may certainly throw a baseball additional than a 16-pound shot used within the shot put. Likewise, all different elements being equal, a stronger particular person can throw each implements even additional as in comparison with somebody comparatively weaker.


Henneman’s Size Principle: Slow vs. Fast Muscle Fiber

Muscle fibers are recruited sequentially based mostly on want. That is, the decrease the demand, the less fibers required and the higher the demand, the extra fibers required. Low-demand efforts recruit the smaller, decrease threshold, slower-to-fatigue motor models.


When extra effort is required, the bigger, larger threshold, faster-to-fatigue motor models are referred to as upon. It makes excellent sense and explains why you may jog for an extended time as in comparison with sprinting, or why a lighter resistance will be moved for extra repetitions as in comparison with heavier resistance.



The “slow” versus “fast” muscle fiber classification is a misnomer and has created mayhem amongst each the scholarly-educated and the typical Joe Schmoe coach and trainee. Conventional knowledge suggests the smaller, gradual muscle fibers contract slowly and isn’t able to “fast” muscle contraction.


Similarly, bigger, sooner muscle fibers are regarded as the one fibers recruited for lightening-fast muscle exercise. Yes, gradual fibers do contract comparatively slower than quick fibers, however the distinction is between 60 to 90 milliseconds. Yes, milliseconds. This distinction is nearly negligible.


Understand the quick versus gradual fiber classification doesn’t solely seek advice from the velocity of contraction. It additionally refers to a fiber’s fatigue capability. The bigger, higher force-producing muscle fibers are sooner to fatigue as in comparison with gradual fibers, which exert barely much less force-output however are slower to fatigue.


An explosive, bodyweight-only vertical bounce is a superb instance:


  • A single maximum-effort bounce recruits each gradual and quick fibers. Although it’s high-effort, it creates minimal fatigue due to its brevity. Perform a number of jumps and fatigue will finally ensue due to the higher demand and recruitment of upper threshold, sooner fatiguing fibers.
  • Now, bounce whereas holding heavy dumbbells or carrying a weighted vest. What occurs? The velocity of motion and bounce top will lower as a consequence of gravitational pull, however you can be utilizing extra muscle fibers. Jump a number of occasions and fatigue will come sooner as a result of extra fibers are initially required (the faster-to-fatigue kind). This higher-demand occasion can not match the timeframe as leaping with out resistance.
  • Finally, use a five-repetition most (5RM) resistance in a squat or deadlift and attempt to bounce (which I don’t advocate, by the best way). Because it’s ultra-high demand, a big pool of muscle fibers can be recruited, the resistance can’t be moved quick, and fatigue can be realized shortly.


Genetics, Body Type and Your Ability to Contract Muscle

Touching simply briefly on this subject, your physique kind, and the neuromuscular system can have an effect on your capacity to contract the muscle and carry out, all different elements being equal:


  • Longer limbs might transfer slower than shorter limbs.
  • Having distinctive tendon origins and insertions might let you exert higher drive/velocity as in comparison with poor origins/insertions.
  • Greater muscle mass might exert extra drive than smaller mass.
  • Possessing extra high-threshold, quick muscle fibers might let you exert extra drive than possessing extra slow-type fibers.
  • If you don’t “look the part” (i.e., small muscle tissue, gangly, over-fat) however can contract muscle/exert drive with above-average capacity, you most likely have good neurological capacity (muscle fiber-nervous system “hook-ups”).


Training Mode Implications

  • If you despise gravity, transfer to the Moon.
  • Relatively heavy resistance requires the recruitment of many muscle fibers, together with the high-threshold, higher force-generating fibers.
  • High-threshold/higher force-generating fibers are utilized in explosive/velocity actions exterior the burden room in sports activities competitors.
  • Relatively heavy resistance can’t be moved quick. If you may transfer a resistance quick, it’s mild relative to your capacity.
  • Although inherently unsafe, transferring comparatively quick with resistance can recruit and overload many fibers supplied most repetitions are achieved (i.e., intention for full volitional muscle fatigue).
  • If a quick velocity of motion have been essential in resistance coaching, what quantity of resistance would you utilize and how briskly would you progress it? 35%, 50%, or 80% of a 1RM? 115, 360, or 600 levels per second?
  • You don’t have to maneuver quick when resistance coaching to develop energy. Power = drive x distance/time. Get stronger, (improve drive) then apply your sports activities abilities/timing (maximize distance and time), which results in this:
  • Move quick when talent coaching, unabated by resistance. Refine and hone sport-specific abilities as they are going to be required in competitors.



1. Brooks, G.A., T.D. Fahey, and Okay.M. Baldwin. (2005). Exercise Physiology: Human Bioenergetics and its Applications. New York, N.Y.: McGraw-Hill Companies.


Please enter your comment!
Please enter your name here