Dr. Andrew Huberman, Ph.D. is a Professor of Neurobiology and Ophthalmology at Stanford University School of Medicine. His lab focuses on neural regeneration, neuroplasticity, and brain states such as stress, focus, fear, and optimal performance.
In this episode, Andrew Huberman explains the science behind a range of motion and flexibility and how to increase them by using science-supported protocols.
Host: Andrew Huberman (@hubermanlab)
Flexibility involves neural (nervous system), muscle, and connective tissue working together
The nervous system controls muscles via motor neurons which control the contraction of muscles
Muscles (temporarily) shorten when contracted and (temporarily) lengthen when relaxed
Muscle spindles wrap around muscle fibers and send information from muscle back to the spinal cord
If a muscle is stretched, the muscle spindle will spend information to motor neurons and cause the muscle to contract to avoid overstretching and bring the range of motion into a “safe” zone
Mechanism 1 – Stretch via motor and sensory neurons: motor neurons contract muscles, spindles sense stretch within a muscle, and sensory neurons send signals to motor neurons to contract and bring the body back within a safe range of motion
Golgi tendon organs(GTOs) sense how much load is on a given muscle and have the ability to shut down motor neurons and accompanying muscle contraction
GTOs make it impossible for muscles to contract
Mechanism 2 – Load via GTOs: when muscles are overloaded, GTOs will send a signal to shut down motor neurons and prevent muscle contraction to allow muscles to stretch and return to safety
Stretching consistently over time will change muscles
When we stretch, muscles aren’t literally getting “longer” – the myosin and actin conformation is changed
The length of muscle belly and location of insertions relative to connective tissue and limbs is genetically determined
Interoception: the ability to sense what’s happening in our own body
Exteroception: the ability to sense things in the environment around us
The Insula region of the brain is responsible for processing and making sense of the external and internal world
Posterior insula: houses a dense collection of neurons (von Economo neurons) concerned with somatic experience, how movement makes us feel, whether to override pain and discomfort and lean in or avoid the movement
Von Economo neurons: connected to brain areas that can shift state internal state from sympathetic activation (alert, stress) to parasympathetic activation (rest)
Von Economo neurons allow the brain to override spindle mechanisms and subtly override reflexes that would cause us to contract
Von Economo neurons pay attention to what’s happening in the brain and body as well as control the amount of calmness or alertness in response to stimulus
Experiment: while standing, try to touch toes and see how far you get, then; try again, this time contracting quadriceps muscles – you should reach farther because these muscles are antagonistic (this is thanks to GTOs)
If a muscle is tight, you can leverage muscle anatomy by contracting antagonistic muscle – e.g., for tight quadriceps, contract hamstrings; for tight hamstrings, contract quadriceps
Types of stretching: dynamic, ballistic, static, proprioceptive neuromuscular facilitation (PNF)
Dynamic & ballistic stretching involves momentum, as opposed to static stretching where positions are being held for a given time
Dynamic stretching: less use of momentum towards the end range of motion
Ballistic stretching: swinging of limbs through a full range of motion
Static stretching: holding stretch through end range of motion
Active static stretching: dedicated effort to put force behind stretch to extend the range of motion
Passive static stretching: relaxing into the furthest range of motion
Proprioception involves knowledge and understanding of where our limbs are in space and relative to our body
PNFexample: leverages proprioceptive system – for example, using a strap while laying on back to stretch hamstring then trying the same stretch without the strap
To increase limb range of motion, stick to static and PNF stretches
Ballistic and dynamic stretches are useful for improving performance but won’t necessarily increase limb range of motion as much as static stretching
Change in flexibility is dependent on frequency and duration
Hold static stretches for 30 seconds to increase limb range of motion over time – more than 30 seconds is not additionally useful according to the research
Perform static stretches at least 5 minutes per week per muscle, distributed throughout 5 sessions per week to maintain or improve range of motion over time
Improvements in range of motion will take place around 3 weeks
Protocol: 2-4 sets of 30-second hold static stretches, 5 days per week
Sample protocol: 3 sets of 30-second static stretching for hamstrings x 5 times per week
Rest between stretching sets is not as critical as during strength or resistance training, try 1:1 or 1:2
It’s best to perform static stretches once core body temperature is elevated (i.e., post-workout or calisthenics)
Static stretching can limit performance if done before cardio or strength training workout
Key elements of stretching protocol: (1) feel the muscles as you stretch & stretch to the end of a range of motion at that moment (it will vary); (2) low intensity (non-painful/straining) static stretching is at least as effective as more intense stretches (pushing to pain)
While static stretching is best reserved for the end of the workout, it does have a place prior to exercise if it will help your body overcome limitations and put your body in a greater position of safety
Stretching induces relaxation at a local and systemic level
Tumor volume in cancerous mice was 52% smaller in mice in one-month stretch protocol versus control – unlikely due to stretch alone but maybe relaxation allows the nervous system to combat tumor growth more effectively
Pain tolerance of yoga practitioners is at least twice as high as non-yoga practitioners – likely related to increased volume of the region of the brain responsible for interoception
Force enhancement after stretch of isolated myofibrils is increased by sarcomere length non-uniformities (Scientific Reports)
Microfluidic perfusion shows intersarcomere dynamics within single skeletal muscle myofibrils (Biophysics and Computational Biology)
The Effect of Time and Frequency of Static Stretching on Flexibility of the Hamstring Muscles (Physical Therapy & Rehabilitation Journal)
The Relation Between Stretching Typology and Stretching Duration: The Effects on Range of Motion (International Journal of Sports Medicine)
A Comparison of Two Stretching Modalities on Lower-Limb Range of Motion Measurements in Recreational Dancers (Journal of Strength and Conditioning Research)
Stretching Reduces Tumor Growth in a Mouse Breast Cancer Model (Scientific Reports)