Week 5 - Science of Hypertrophy

8/8/2019 Week 5 - Science of Hypertrophy

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Jon Cree


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What is hypertrophy?

Explain the physiological components ofhypertrophy


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Increase in size

Lean muscular mass Skeletal Muscle

Cardiac Muscle

Increase muscle cross-sectionalarea (sarcomeresin parallel)

Opposite Atrophy


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Contact sports Protection

Increase impact forces

Bodybuilding Competition

Increase in strength/power Pennation angle

Number of filaments


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Pennated muscle

Majority: skeletal

Attaches @ angle

Increased MF CSA

Increased A-M CBs

-VE:too much Hypertrophy


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Optimal Length-tension relationship increases number of cross bridges therefore STR


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Decreased ROM

Decreased performance


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Increase the number of A-M CBs

Satellite Cells

Found in sk

eletal muscle Aid growth, maintenance & repair

One nucleus

Become active due to trauma

Migrates to damaged area

Donates nucleus to muscle cell

Increases density of A-M cross bridges

48-H


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Increase in number of muscle fibers

Splitting

Found among animalpopulations

Unproven in human skeletal muscle


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Two mechanisms:

Increased muscle tension (Mechanical stress)

Intramuscular energy depletion (metabolic

stress)

(Nosaka etal. 2003;Stone etal. 2007; Zatsiorsky etal. 2006)


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Upstream signalling Downstream events

1. Mechanical & metabolic stress

2. Signalling from mechanical stress on musclefibers,hormonal response and inflammatory

response

3. Protein synthesis leading to hypertrophy


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Shown to be apowerful stimulantto muscle

growth

Eccentric contractions (over Iso & Concentric)

DOMS

Disruption of sacromeres


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Repeated exercise

Decreased function

Increased enzyme activity Breakdown of cell structure

Concentric over eccentric Concentric requires more energy


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Mechanical & metabilic stresses cause growth

signalling due to muscle contractions,

hormonaland inflammatory responses

1. Muscle Contractions2. Hormone Response3. Immune Response


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Directly signalprotein-kinase pathway

Increases protein synthesis

Therefore muscle growth


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Anabolic hormones stimulated during

resistance training

Hormones signaland promote growthby:

GH

TST

IGF


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Produced from pituitary gland

Aids production of muscle & bone

Also regulates blood glucose levels,

stimulates fattyacids from fat cells


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Helps to promoteGH responses bypituatory

gland

Promotes male sex characteristics

Influences structuralprotein synthesis

Therefore :Size and strength


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Hormone secreted by skeletal muscle

Produced in response toGH

Provides aprolific role in protein anabolism

Encourages satellite cellproduction


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Mechanical stress micro-trauma

Immediate infiltration of cytokines

Neutrophil & Macrophage production


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Concentric, eccentric, isometric

Greater levels of myofibrillar damage

Athletes: All 3 types Sports performance

Stabilization

Force production

Supramaximal loading

110% 1RM

Concentric,eccentric, isometric


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% of 1RM

50-75% (NSCA)

60-70%RM Beginner

70-80%RM Intermediate

70-100%RM Advanced

110%RM (keogh etal. 1999)

Kraemer & Ratamess (2004)


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Low moderate to begin with

Moderate high for advanced

Continuing low-moderate:Sarcoplasmic &

Type 1 muscle fibers (Bodybuilders)

Non-functional

(McDougall etal 1982; Fry 2004)


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TUT:Totaltime a muscle is under stress p/rep

Not widely researched

Written in 3 number sequence: Eg: 321 tempo (6 seconds p/rep)

3s descending; 2s pause; 1s ascending

Bird etal (2005) 2s Con; 2s Ecc, 1s Iso

Goto etal (2004) 1s Con, 5s EccGH production


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Total Vol:product of sets x reps

Vol load:Product of sets x reps xload

Hightotal vol & low rest & moderate load

Kreameretal: 10RM + 1 min rest

5RM + 3 min rest

Produced more resting anabolic hormones

(IGF,GH,TST)


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Important in dictating anabolic hormone

stimulation

Rest intervals


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Optimal stimulus for hypertrophy is 2-3

sessions per muscle per week

4-6 training sessions per week

Alternatively 2 sessions per day of 30-45 mins

Helps counteract catabolism if diet is correct

(Kraemer etal 2004; Wernbom etal 2007)


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Multi-joint exercises promote higher levels ofanabolic hormones

Fatigue in larger muscle groups prior tosmaller muscle groups: Stabilization Injuryprevention

Concurrent muscular usage

(Bird etal. 2005; Chiu &Barnes, 2003)


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Week 5 - Science of Hypertrophy