KIN Neuromuscular Adaptations to Resistance Training

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General Facts on resistance training

1. 6 months of resistance training can increase strength up to 100% of basline levels
2. Similar percent gain in young vs. old and men vs. women
3. Resistance training is the only exercise mode that the body can adapt to with only a single exposure.

To measure effectiveness of resistance training

See how it affects muscle soreness. If you are sore you did enough. If not sore, you did not do enough. Even if you didn't feel sore, can measure blood to see mudcle damage. Creatine kinase, when in blood stream, muscle cells have been damaged. Meausre conc. of CK to measure muscle damage. Troponin I which is part of sarcomeare in muscle also can be tested to see if damage.

Muscle Strength

Maximal force that a muscle can generate. Typically measured with a 1 RM test. 1 RM test only good if exercie trained and normal weight used. Bad test if newbie. Need to do 3 reps max so guessing too difficult

Muscle Power

Measure of how quickly one can move a fixed force
Force x (distance/time)

Muscle Endurance

Ability to maintain a near maximal muscle force.
# of reps at 1 RM test.

Used in endurance training. 3 sets 80% RM, 2 sets 8-10, 3rd set to failure. If 15 to 16 reps on last set, weight not enough. Good way to track progression.

4 Factors to Consider when designing a Resistance Program

1. Target muscle or muscle group
2. Intensity of the training
3. Number of reps per set
4. Number of sets per workout

No magical way to do resistance training. Lower weight and more reps tone, not build muscle. Few reps and high weight build strength. For strength pyramid not good. Instead highest weight lowest reps better. If want maintenance, then in between.

2 Phases of Strength Gains

1. Neural Adaptation
2. Muscle Hypertrophy

Neural Adaptation

1. Synchronization of motor unit recruitment (when start training muscle doesn't know how to contract together well)
2. Decreased inhibitory signols from golgi tendon organ (GTO in tendon--neurological sentor detects muscle force)
3. Decreased antagonist co-activation
4. Increased motor neuron firing

Muscle Hypertrophy 3 types

1. Transitent hypertrophy - due to fluid (shor term makes muscle weaker) accumulation during cotractio
2. Chronic hypertrophy - structural increase in size (long term...want this to happen)
3. Fiber hypertrophy - primary cuase of chronic hypertrophy.

Tendon

Connects muscle to bone

Ligament

Bone to bone

Stength gains time course

Times wher lots of benefits and then none. Can't predict in individuals. That inconsistancy in response is why people drop from programs especially if 2 people when one sees gains and other doesn't

Fiber Hypertrophy

Increase in muscle cell size.

Fiber Hyperplasia

Increase in muscle cell number
May occure in some animals ie cats (NOT chickens, rats or mice)
Does NOT occur in humans or occurs at such a slow rate that it does not have an effect. Can be seen in children but hormones change later in life

Resistance Exercise Modes

1. Free weights
2. Machine weights
3. Downhill running (cause eccentric load on legs. Need to know max at flat then 150-160% of decrline.

Resistance training and fiber type

It is not possible to change physical fiber type
It is possible to change the properties of existing fibers (this typically occurs in the intermediate fibers but can adapt at any fibers????)
Changes typically manifest in 15 to 20 weeks.
4 to 7 weeks hypertropy.

Acute Muscle Soreness

Pain felt immediately after exercise (short term)
Typically disappears within a few minutes, after blood stream has cleared the acid and edema

Causes of Acute Muscle Soreness

1. Accumulation of acid (esp. if exercise with strong anaerobic component)
2. Tissue edema (transient hypertrophy)sensors detect pain for it. Typically disappears within a few min. After blood stream has cleared the acid and edema. Transient hypertrophy also disappears after a few mins.

Delayed Onset Muscle Soreness

AKA DOMS
Primary cuase is eccentric muscle damage and subsequent immune system response (within muscle itself)

Key phases of DOMS

Structural damage (forced lengthening)
Immune system response

Damaged Muscle

Z line separates sarcmere in first slide but there is "Z-line streaming" in the second that shows where sarcomeare MIGHT be. Hallmarks muscle damage present

6 Stages of DOMS

1. Eccentric contraction causes structural damage to the muscle fiber
2. calcium homeostasis is disrupted resulting in necrotic cell death (can't maintain Ca in muscle cell)
3. Intramuscular contents stimulate nerve endings
4. Immune system activation and improper killing of damaged and proper killing healthy tisuse Immune system clears saway large areas.
5. New muscle fibers form to repair muscle damage (from stem cells)
6. Muscle strength restored.

Muscle adaptation

Force length contracion model in lab. Ellicits eccentric action on machine. Resist pressure that is given. If too much won't be able to expend for 1 week. However body adapts and can't hurt that way again.

GTO and Neural Adaptation

First time training neural sesor goes off goes to spinal to muscle telling not to contract as much and creates opposite muscle to help workd. So reduced work on target muscle int the beginning so main muscle weaker.

Motor neuron firing

The faster neuron fires, the stronger the force of contraction.

Definition of muscle hypertrophy

Increase in muscle size and number of contractile units in muscle.

Chronic Hypertrophy

Larger, more contractile units. Long term you want this to happen as it is a streuctural increase in size.

CK accumlation

Accumulation of water in muscle so increase risk of muscle injury. Capacity less.

Neural adaptation definition

Muscle itself gets stronger but no change in size of muscle.

Eccentric exercise

Muscle is much stronger on eccentric side (~30 - 40% stronger) Eccentric contraction only one that counts for strenthening. Body has to clear out damaged muscle afterwards. New muscle cell comes form stem cells. Gain memory from damaged tissued up to 3 months after

Sliding filament theory and muscle gain

Does not explain isometric contraction or eccentric contraction causing muscle gain.

DOMS time course

also muscle troponin, infalmm, muscle strength, CrK

Biphasic of Imflammation Response

Phase I (24h)
Phase II (46-72h) depends on degree of damage

Phase I of Inflammation Response

24 h
Related to damage cause during eccentric exercise
Not related to acid build up or edema
Not related to immune system

Phase II of Inflammation Response

48 to 72 h
Related to secondary damage of healthy tissue by the immune system
Not related to initial eccentric exercise
Caused by disturbance in the immune system

Found by using model of real tissue in clulture. Use WBC and co-cultured . Cells would attack and kill helathy tissue.

Possible Treatment for DOMS

Best Treatments Time and rest from activity
RICE NO. Ice only good for pain control. Heat good with sprains. ANti-inflammatories don't help with healing process. Anti-inflams in overuse injuries not good as prevent healing but in competitive athlete may be only option. Not good for bone related injuies.

2 Causes of Muscle Atrophy

1. Immobilization
2. Detraining

Immobilization and muscle atrophy

Typically due to injury
Changes start to occur within 6 hours
4-5% strength decrease per day in first week.
Affects slow twitch muscles (endurance impaired)

Now try to get you moving leg after surgery.

Detraining and muscle atrophy

25% of previous gains lost in first week.
All adaptations lost in half the time it took to gain them.

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