34. Mechanotransduction Khan KM, Scott A. Mechanotherapy: how physical therapists' prescription of exercise promotes tissue repair. Br J Sports Med 2009;43:247-252. Kaneko D et al. Temporal effects of cyclic stretching on distribution and gene expression of integrin and cytoskeleton by ligament fibroblasts in vitro.Connect Tiss Res 2009; 50(4), 263-269.
Born and raised in small town Canada. PT at Queen's University in 1988; completed the highest level of training in MDT, the Diploma, in 1998. One of 330 in the world. Involvement in the US national track and field program (3 national teams) and the 1996 Summer Olympics Endurance sports coaching: this past summer, Western States 100 under 24:00 + double World Masters world champion at 800m and 1500m; sprint triathlon to Ironman to UT triathlon team head coach)
Adjunct faculty at ACC and TSU, spoken at ASU and MII, MIUSA, APTA After 20 years, author
Why this topic? Has special significance to me with the background I bring to the table. Having taught therapeutic exercise at the entry level of PTA practice, worked with all levels of athletes and coaches, other PTs
Cellular physiology is ignored by physical therapists, health care providers, coaches, athletes, trainers …
The slides have been updated – this is the extended dance remix version of the originals. I will post an updated presentation / pdf on my website.
End time = 10:00
14 groups End time = 0:20:00
There is a big difference between principles – the WHY we do – and practices – the WHAT we do. We will start this discussion with the principles of therapeutic exercise, and then discuss the practical applications. Just having more tools in the toolbox isn't sufficient. You have to know when to use a screwdriver – you can't use it for everything!
The gold standard of clinical practice!
- description - training effect and detraining - periodization; time is important - everyone focuses on the stimulus – but what about the recovery?
Being in balance – is human physiology ever "out of balance"? We maintain stable internal physiological conditions
Balancing rate of adaptation with rate of application of training stimulus; importance of recovery and adaptation + time (conversely, detraining/periodization, under-recovery) Balancing stimulus with response Balancing mechanical loading with functional response Balancing afferent input with efferent output
Allow homeostasis to occur GIGO ** afferent and efferent – efferent response to afferent input (inhibition/facilitation)
specific adaptations to imposed demands Wolfe's Law – initially bone, now all tissues Form follows function: are we seeing overuse injuries or under-recovery injuries? summarized by using example of astronauts and deep sea divers;
"ability to perform work" = FVT Capacity = functional responses such as strength, endurance, bone density
– need critical parameters of training/exercise stimulus to attain the desired physiological response - critical parameters = therapeutic dosage (rate/load sensitivity, duration, intensity), frequency; time for adaptations, viscoelasticity
If you use energy systems, how does interval work increase aerobic capacity? Current "systems" are still a little fragmented Must be a way to synthesize all into a broader overview
Peter Senge – perhaps one of the most important PT references I have read that wasn't a PT reference!
My model of physiotherapy, performance, and prevention (mechanisms are the same) Model For Human Performance – Mechanical + Cognitive + Nutritional Draw diagram on flip chart
Repeated movements; sustained postures
Stress reaction tibia – 35 yr female Osteoporosis – 80 yr female Osteoarthritis knee – 65 yr male Capsular tightness elbow – 20 yr male Achilles tendinopathy – 30 yr female Lumbar derangement – 18 yr female Weight loss – 40 yr male Muscle strength – 25 yr male Muscle endurance – 25 yr female Post-surgical ROM TKR – 70 yr male Neuro facilitation stroke – 60 yr female Neuro inhibition – 60 yr male Flexibility hamstrings – 25 yr female Aerobic/deconditioning – 40 yr male End time = 0:50:00
All mechanisms are the same! Have been working from this premise since 1992.
Given the systems and tissues, what are the mechanisms at play? What is the appropriate mechanical loading strategy to stimulate cellular (and system) activity and attain the desired response? What are the critical parameters? Nagi's model of the process of disablement … disease – impairment ([practice patterns = cardiopulmonary, musculoskeletal, neuromuscular, integumentary) – functional limitations (physical, psychological, social) - disability
Impairment – function
The primary limiter to performance All physiological mechanisms Brain – Synapse – Neuromuscular Junction – Muscle and fuel supply Draw diagram on flip chart
Mechanotransduction – "mechanical loading stimulates protein synthesis at the cellular level"; mechanical loading stimulates neural facilitation/inhibition at the cellular level. What mechanical loading will stimulate the correct mechanisms at the cellular level to promote the desired responses? (1) mechanocoupling (mechanical trigger, cell deformation) (2) cell–cell communication (the communication throughout a tissue to distribute the loading message – singalling proteins) (3) the effector response (tissue “factory” that produces and assembles the necessary materials in the correct alignment)
What cells are stimulated to attain the desired response? What systems can be assessed? Stimulate activity – Appropriate mechanical loading – critical parameters – response Nervous: neuroblasts Connective: fibroblasts / osteoblasts Muscle: myoblasts Epithelial Systems-based Repeated movement; sustained loading Recovery-Centered Training focus Circadian rhythms
What is the appropriate mechanical loading strategy to stimulate tissue/cellular activity? What is the critical dosage required? Stress-strain curve, force-velocity, length-tension Afferent and efferent – inhibition of quadriceps, facilitation
collagen = compression, tension; bone = compression, shear, flow
- motor recruitment, tension - glycogen repletion + glucose transporters
- CNS recruitment, motor patterns - Na/K - glucose transporters, esp. With blood glucose End time 1:20:00
What mechanical loading will stimulate activity of cells/systems? What is the desired cellular response? Critical parameters for all mechanical loading strategies End time 1:30:00 (break if needed)
intensity is your friend, not your enemy Most mechanisms are intensity (load)-sensitive
Circadian rhythms? Scott A, Khan KM, Duronio V, Hart DA. Mechanotransduction in human bone: in vitro cellular physiology that underpins bone changes with exercise. Sports Med. 2008; 38(2): 139-60. "Finally, the data suggest that exercise should emphasize the amount of load rather than the number of repetitions. End time 1:40:00
Discuss critical parameters for all scenarios Nagi's model of the process of disablement … disease – impairment ([practice patterns = cardiopulmonary, musculoskeletal, neuromuscular, integumentary) – functional limitations (physical, psychological, social) – disability End time 1:55:00
The game changer? Or the same as normal tissue development? Scientific literature End time 2:05:00
Appropriate and inappropriate responses Incl. RCT, MDT
progression dependent upon ability to adapt to imposed demands; increased time required due to age, metabolic state, etc. Intensity is your friend, not your foe – as long as you and the patient have a good understaninf of hurt vs harm
Daily reassessment is a hallmark of the McKenzie method – and is critical to optimal progression of loading! The body wants to adapt – if you give it the stimulus to do so. under-recovery; symptoms (hurt not harm) Mechanical Loading Strategies based on desired responses Recovery and Adaptation – using Model of Human Performance - Appropriate cognitive, mechanical, nutritional responses End time: 2:25:00
(weak stimulus, diminished dosage = diminished or no response, or no response that adds any value to what the patient can do themselves); garbage in, garbage out Modalities i.e. ultrasound – vibration = mechanical loading; estim
A quote from my book End time 2:40:00
Is mechanical loading enough? As compared to other treatments Can the patient do it all themselves? Patient-generated forces, competent self care Our Role? Opportunity for profession to stake our claim as "health mentor" vs "fixer" Group Discussion – Role of PT? End time 2:55:00
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