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Strength Training - What is the evidence and what do we do?

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Michael Redshaw

on 29 April 2014

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Transcript of Strength Training - What is the evidence and what do we do?

Strength Training
What is the evidence and what do we do?
Strength Training
Types of Contraction
Isometric
- when the muscle is working against an immobile load.

Isokinetic
- when the muscle actually moves the joint.

Can be subdivided into two types:-

1)
Concentric
- muscle gets shorter and performs joint movement.

2)
Eccentric
- muscle lengthens and works to control the joint movement against gravity.


Isometric contractions
Isometric - maintenance of muscle activity when the joint not to be moved through range.
Both submaximal and maximal isometric muscle actions can induce muscular hypertrophy.
Isometric exercises only strengthen the muscle at the angle at which it is trained.
To improve strength, the most efficient use of isometric exercises is 15-20 maximal voluntary contractions held for 3-5 seconds (Fleck and Kraemer, 2004).
Speed of Exercise
Speed of eccentric exercise does not appear to have specific training effects.

Strength usually improves most at the velocity at which training occurs.

Importance of activity specific exercise?
Muscle Fibre

Concentric or Eccentric
Eccentric exercise increases tension per individual cross bridge causing mechanical disruption of the ultra structural elements within the muscle fiber (MacIntyre et al,2008)

Grigg et al (2008) Eccentric loading invokes greater reduction in TA thickness immediately after exercise BUT full recovery is achieved in a similar time frame to concentric exercise.
Concentric versus Eccentric Conclusion
Based on best evidence available it appears that eccentric exercise may reduce pain and improve strength in lower extremity tenodesis BUT whether eccentric is more effective than other forms of therapeutic exercise for the resolution of tenodesis symptoms remains questionable (Wasielewski and Kotsko, 2007).
Bilateral or Unilateral?
Contralateral strength training effect.
Increased motor neuron output rather than muscular adaptations.
Precise physiological mechanisms not understood but likely to involve cortical, sub cortical and spinal level.
Munn et al (2005)
Pain on exercise?
Muscular discomfort during exercise is OK. Microtrauma = hypertrophy.

Debatable regarding tendonopathy.
More recent evidence around pain enduring eccentric TA exercise.

Alferdson protocol says to carry on through moderate pain.

But, only 3/18 people 'happy' doing Alferdson painful heel drop protocol in Ram (2013) study.

Verbunt et al (2005) Increased muscle inhibition seen in patients with chronic LBP who have high pain levels and high levels of psychological distress.

All evidence regarding patella tendonopathy says no pain should be endured during eccentric loading.
Contraction...
Muscular Strength
Definition:

Maximal force that can be generated by a specific muscle or muscle group (expressed in newtons or KG).

Q: What is power?



More on the assessment of muscular strength later...




Intro

Exercise Prescription or Movement Prescription?

Do the specifics of exercise prescription really
matter or is it time, advice and movement that
really makes the difference or both?

Why do you give exercises?


Muscle Fibre Composition
Type I
- slow aerobic twitchers (uses ATP)

Type II (IIa and IIb)
- fast anaerobic twitchers (fires more quickly)

How much force is required and how quickly does this muscle need to contract?

The composition of each muscle is unique and genetically determined mixture of both types?
Q: Implications?
Implications for Program Design
Training load needs to reflect both the role of the muscle and it's fibre composition...

Q: BUT in what context?
Other Considerations?...
Aging
Recovery
Fatigue
Injury

MVC or ISOMETRIC testing. (Limited to specific muscle group and joint angle).

1-RM, 6-RM or 10-RM for ISOKINETIC testing. (Assessment of maximal muscle tension throughout a range of joint motion set at a constant angular velocity - 60 degrees / second).
Testing 1,6, OR 10-RM... potentially problematic especially during a flare up or acute injury!

Test contralateral limb to bench mark future rehab.

How?...
The Load...
Population Frequency Intensity Type Time

Healthy Adults 2-3 days / wk 1 x point 8-10 ex. < 60
48 hrs rest of volitional 1 / major minutes
for 8 wks fatigue muscle grp.
for long term
effects Endurance 10-15
Strength 8-12
Elderly Persons 2-3 days / wk 1 x 10-15 8-10 ex. < 20-30
48 hrs rest RPE 12-13 1 / major minutes
for 8 wks "somewhat hard" muscle grp.
for long term
effects
Adapted from the ACSM Guidelines for prescribing resistance exericse in healthy adultas and elderly populations and Hopker and Jobson (Performance Cycling 2012)
Resistance Training Guidelines
G
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Case Studies
In groups of 4
Put a strength training plan together
Case study 1 or case study 2
Design 3 exercises all of your choosing

1) 1 x isolation exercise
2) 1 x exercise in weight bearing
3) 1 x exercise with a return to function focus
Overview
Intro, definitions and thoughts

Muscle physiology

Resistance training guidelines / program design

Testing to prescribe effectively

Other considerations

Power is the rate of doing work,

where work = force x distance

Power (watts) = work / time
What is the most important component of any training program?
Testing?...
Significant strength gains with correct use of resistance bands. Cheap and practical to use. Useful for testing...
Newsam (2005) demonstrated band lengths required to perform an 8-RM with 3 exercises for the shoulder.

IR (Blue, mean 29cm),
ER (Blue, mean 35cm, Green 25cm),
Diagonal pull down [Full flexion to opposite knee, straight elbow], (Blue or Green 36cm)

F
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G
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Do you document your oxford score as power or strength?
Trained Cyclists 2 days / wk 2-3 x 4-10 RM 5-6 ex. 2-3min
major R. b/t
for 8-12 wks muscle grp. sets.
for long term
effects

In season x 1 / wk HITT
Different parts of the body age at different rates.
Pattern however is one of decline!

Slow linear decline from age 35 to 50, then
there is some acceleration. A steep exponential
decline from 60 and then again at 70!

Sacopenia
7-17% decline in muscle fibre strength / decade.
Rate of decline is similar in trained & untrained.
Attributable to intramuscular changes both in
the reduction in Type II fibres to slower versions and in the
ability of older muscle to extract oxygen (Hopker 2012).
Adaptation
Changes in skeletal muscle protein occurs at a much slower rate in response to training loads

KEY POINT: Supporting the argument that older muscle requires a greater training stimulus to achieve the same muscle adaptation as younger muscle.

Relationship between muscle fibre loss and age-related metabolic dysfunction (Akaski 2013).
IMPLICATIONS: Include HITT to maxmise anaerobic potential and stimulation of fast twitich muscle fibres.
Isometric contractions exhibit less
fatigue than dynamic contractions.

Eccentric greater than concentric.
Age has no effect on recovery rates and performance in cyclists completing a 30min TT over 3 consecutive days, suggesting similar rates of recovery exist.

Cycling specifically uses concentric muscle contractions which may in part explain the higher muscle damage seen in runners since this utilises both eccentric and concentric contractions.

Adaptations to load are sport or activity specific and whether isometric, concentric or eccentric work are involved and therefore how much remodelling of damaged muscle fibres is required.

8 weeks + of consistent training required for significant gains to be realised.
This is where we come in!
Mafi et al (2001) TA ecc vs conc. No difference in pain levels between treatment groups. More pt's satisfied in ecc group.

Camargo (2010) not a lot of difference in work rate of RC muscles in eccentric versus concentric exercise (dynamometry).
Practical... Determine what band length you require to calculate your own 8-RM for the above exercises in
groups of 4. Q: Are you similar to the above or are you stronger than Newsam's subjects!...
Full transcript