Download Neuromuscular Adaptations

Paul Thawley MSc
Neuromuscular
Adaptation
Is this predominately
what Physio`s do ?
Basic definitions
 Strength
 Maximal amount of force a muscle or a muscle group can
generate
 Power
 The rate of performing work
 FxV
Mechanisms influencing
muscle strength
Structural
Neural
Mechanical
• Hypertrophy
• Vascularization
• MHC change
• Conn. Tissue
• Recruitment
• Synchronization
• Inter-Musc
Coordination
• Intra-Musc.
Coordination
• Muscle Mechanics
• Pre-stretch effect
Time-course of adaptations
Progress
Strength
Hypertrophy
Neural adaptations
Time
(Modified from Sale, 1988)
High level brain
controller
Specific
Adaptations
Motor Cortex
Sensory
receptors
T
R
A
I
N
I
N
G
Spinal Cord
Specific MU activation
Muscle
Force Output
Force generation and fiber
recruitment
Specificity
High Force
0 Velocity
• Increase in maximal
isometric force (e.g. Kitai &
Sale, 1989; Rutherford &
Jones, 1988)
• The improvements are in
the range of 18% of the
range of motion used for
training (Kitai & Sale, 1989)
F
V
• Dynamic training is
superior to static training if
the outcome is dynamic
performance
Mechanics Specificity
Concentric training has been
shown to be effective in improving
dynamic muscle performance (e.g.
Johnson 1972; Komi & Burskirk,
1972)
Eccentric training has been shown
to be effective in improving
dynamic performance (e.g. Komi
& Burskirk, 1972)
Specificity
180
160
140
120
100
80
60
40
20
0
% increase
training weights
Isometric strength
0
2nd
4th
6th
8th
10th 12th
weeks
From Rutherford & Jones (1986)
Hypertrophy
Size of muscle fiber
30
Strength
25
20
15
10
5
0
0
8
12
24
weeks
36
48
60
What is hypertrophy
• Increase in muscle cross-sectional
area
• This increase has been attributed
to an increased size and number of
actin and myosin filaments and to
additions of sarcomeres within
existing muscle fibers (Mac
Dougall et al., 1979; Goldspink,
1992)
• Not all muscle fibers undergo the
same amount of enlargement
Hypertrophy
The hypertrophic response
depends on the stress
applied to the muscle
structure
New sarcomeres are
formed nearby the damaged
muscle cell.
This is regulated by posttranscriptional events
An example
Before
2 Days after
7 Days after
1 x 10
2 x 10
From Hortobagyi et al. (1998) JAP
Hyperplasia
• Increase in the amount
of muscle fibers
• It has been
demonstrated in animalbased studies
• Contradictory evidence
in humans
Stretch as an hypertrophic(McComas,1994)
signal
Stretch
Release of soluble factors from muscle fiber or
extracellular matrix
Prostlaglandins ?
Activation of second messenger system in fibers
Induction of immediate early genes
Transcription of muscle genes
Muscle fiber hypertrophy
Arachidonic Ac
Phospholipase
Protein kinase c
Tyrosine kinase
Hawke and Garry, JAP (2001)
Effective exercise approach
1. Eccentric training is effective in determining
hypertrophic responses
2. Stretching of muscle fibers affect gene transcription
3. Eccentric mechanical work determine release of
prostaglandines
4. Prost. affect immediate early-genes controlling
transcription of other genes in the nucleus of muscle cells
5. Specific adaptations occur in the muscle cell
Pain after exercise
•Eccentric contractions may cause muscle discomfort
and/or pain
•It appears usually the following day and can last for more
days
•This phenomen is referred to as “Delayed Onset of Muscle
Soreness”
• This is due to damage to the muscle fibers causing edema,
swelling and inflammatory responses in the muscle cell
Muscle damage
Detraining
From Hakkinen & Komi (1985)
30
%
C
H
A
N
G
E
Heavy resistance training
Detraining
25
20
15
10
5
0
0
4
8
12
16
weeks
20
24
28
32
36
Aging
30 Years old
F
50 Years old
70 Years old
Time
Hormonal adaptations during
exercise
 Regulation of growth
 Reg. Development
 Reproduction
 Capability of
handling
physiological stress
 Capability of
handling
psychological stress
Effects of exercise on human body
 Exercise represents a
strong stress applied to
human biological
structure
 This added stress
generates physiological
responses aimed to reestablish the metabolic
processes
Resistance exercise and specific
hormones (T)
 In adult men, acute increases following resistance exercise
are observed following adequate stimulus ( multiple sets, 5-10
RM, adequate muscle mass)
 A study by Hakkinen et al. (1988) conducted on professional
weighlifters over 2 years time showed increase in T, FSH, LH.
 Relatively small variations have been found in women.
 Long rest periods are related to an increase in T production
Manipulating the Endocrine
system naturally with resistance
training
 The more muscle fibers rectuited for an exercise, the greater the
extent of potential remodeling
 Only muscle fibers activated by the resistance training are subject to
adaptation, including hormonal adaptation to stress
 To increase Serum Testosterone




Use large muscle-group exercises
Use Heavy resistance exercise (85% to 95% of exercise)
Use moderate to high volume of exercise
Use 60 to 90s intervals
 To increase Growth Hormone
 Use workouts with higher lactate concentrations and high intensity (> 10
RM) with 3 sets of each exercise and short rest periods
 Supplement diet with carbohydrate and protein before and after workout
Overtraining and
Overreaching
 OVERREACHING: An accumulation of training and
non-training stress resulting in a short-term decrement
in performance capacity
 OVERTRAINING: An accumulation of training and nontraining stress resulting in long term decrement in
performance capacity
The main principle
Stimulus
SuperFatigue Recovery compensat
Decrease
Steps to build the program
• Resistance training goal
• Exercise selection
• Exercise Order
• Training load and
repetitions
• Volume
• Rest Periods
Resistance training goals
• Hypertrophy ?
• Maximal strength ?
• Power ?
• Movement specific strength ?
• Mainteinance of strength
Exercise selection
Core exercises
Large muscle areas and multijoint
Assistance exercises
Small muscle areas and single joint
Structural exercises
Load on the spine
Power exercises
Weight quickly lifted
When deciding the exercise
• Consider Exercise technique experience
• Equipment availability
• Training time availability
• Muscle Balance
• Sport-Specific technique
• Previous injuries of the individual
Exercise Order
1. Power, Core and Assistance
•
Stress on power enhancement
2. Upper and Lower body (Alternated)
•
For non- well trained individuals
3. Push – Pull
•
Indicated for circuit training
4. Supersets and Compound sets
•
Two exercise with opposing muscles
•
Two exercise for same muscle group
Assign the training load
Determine 1RM
Or Build F/V rel.
Establish goal
(Hypertrophy, Power?)
Chose % of 1RM
Or load on F/V curve
Decide number of
repetitions
Decide volume
Sets x Reps
For gaining Strength/power
• The weight has to be lifted as fast as
possible
• Use load assignment to increase
maximal strength and optimise power
production
• Every repetition should be performed at
more than 90% of the maximum power
• In this way FT fibers are recruited
For gaining hypertrophy
• Use heavy loads
• Use multiple sets
• Use repetitions to fatigue
• Use eccentric type of training
• Reduce rest between sets
• Recruit all muscle fibers
Adaptations to Exercise Training
Each person responds differently to each training program.
There is a psychological component to training.
The magnitude of the physiological or performance gain is related to the
size of an athlete’s adaptational window
The amount of physiological adaptation depends on the effectiveness of
the exercise prescriptions used in the training program.
Training for peak athletic performance is different from training for
optimal health and fitness.
Neural Adaptations
 Increases in strength due to short term Increases in strength due to
short term (eight to twenty weeks) training are the (eight to twenty
weeks) training are the result of neural adaptations. result of neural
adaptations.
 Neural adaptations can include improved Neural adaptations can
include improved synchronization of motor unit firing and
synchronization of motor unit firing.
Neuromuscular Adaptions
 Specificity
It is important to know that neuromuscular adaptations are closely related
to the specific exercises.
 Exercises
Exercise prescription If you select a small number initially.
 High number of sets
When you were 4 years old and tried to ride your bike for the very first
time, you did not try only once to master the discipline. You tried over and
over again
 High number of Reps
 Load 60% 1RM or 10RM
How?
1. Decide which mm group
2. Decide which exercise
3. Decide how much volume
Eg Hypertrophy 70% of max
=
MU
Patterning below 50% of max
=
MU
Proprioception
 Eg 120 reps @ 40%
 Eg 60 reps @ 70%
Low force Low MU
High force High MU
High patterning
Low paterning
How Do I set Load
Objective
Strain gauge: work out %
Subjective
Lift weight 10 times = 70% 1RM. If pt lifts Wt 20 reps below 50%
1RM
Most MU used in Ecc ? ACL rehab early very functional
Important that Proprioception is linked to all stages of
Rehab!
 ACL
6 wks post op MM atrophy Quads / Hamstrings
Hamstrings to Quads ratio
Speed of contraction
Main mm function of MM groups
involved