Strength Training with Youth and Junior Athletes Dr. Keith Baar University of California Davis @MuscleScience

Outline 1. The relationship between hypertrophy and strength/power 2. The components of strength 3. How can we use nutrition to improve strength 4. What are the consequences of training to improve strength/speed 5. Possible ways to improve connective tissue function with nutrition

Components of Strength/Power 1. Muscle fiber cross-sectional area 2. Neural activation 3. Connective tissue stiffness

Muscle Fiber Cross-Sectional Area Positive Protein Balance Increase protein synthesis to greater extent than protein degradation and a muscle grows

1. Resistance exercise 2. Nutrition

Load Causes Hypertrophy Hypertrophy (% Change)

20 GTN TA

*

* *

15

10

5

0 CON -5

No Weight

Weight

Group

Wong and Booth J. Appl Physiol. 1988, 65:950. High loads are required to increase muscle mass.

Load to Failure

Burd et al. PLoS One. 2010 Aug 9;5(8):e12033. Heavy loads or continuing to failure result in increased protein synthesis after resistance exercise

Strength and Training

Mitchell et al. J Appl Physiol. 2012 Jul;113(1):71-7. Heavy loads or continuing to failure result in muscle hypertrophy.

mTOR and Muscle Hypertrophy Increase in Muscle Mass (%)

20 TA

15

EDL 10 PLN

5

0 r2=0.998

SOL

-5

-10 0

100

200

300

Increase in S6K1 Phosphorylation (%) Baar & Esser Am J Physiol. 1999, 276:C120. There is a correlation between the activity of mTOR 6h after a single bout of ResEx and hypertrophy over 6 weeks of training.

mTOR Needed to Increase Protein Synthesis

Drummond et al J Physiol. 2009, 587:1535. Humans who lift in the presence of the mTORC1 inhibitor rapamycin don't see the increase in protein synthesis after ResEx.

Loading and Protein Synthesis • The activation of mTOR leads to (and is required for) muscle hypertrophy and an increase in strength. • Lifting either light weights or heavy weights to failure activates mTOR and results in the same increase in MPS and hypertrophy. • The increase in the rate of MPS following eccentric and concentric resistance exercise is the same as long as you go to failure. • Increasing training volume does not increase strength gains.

mTOR Growth Factors Load/Tension

Amino Acids

mTOR

Alcohol

Metabolic Stress

Increasing Protein Balance

Tipton et al AJP:Endo 276:E628, 1999. Oral amino acid supplementation tends to decrease breakdown and increase synthesis resulting in a significant increase in balance

Muscle Protein Synthesis (% h-1)

Protein Quantity 0.15

0.10

0.05

0.00 0

0.125

0.25

0.375

0.5

Egg Protein Ingested (g/kg) Moore et al Am J Clin Nutr. 2009, 89:161. The MPS response to oral amino acid supplementation plateaus at 0.25g/kg (~20g of protein)

Protein Source

Tang et al J Appl Physiol 107: 987–992, 2009 The increase in MPS is greater in response to whey than soy, or caesin

Leucine (nmol ml-1)

Differences in Protein Absorption 0.15

Whey Soy Casein

0.10

0.05

0.00 0

30

60

90

120

150

180

Time (min) Tang et al J Appl Physiol 107: 987–992, 2009 The amount of leucine in the blood is greater in response to whey than soy, or caesin

µmol Phenylalanine/kg/min

Absorption is a Key Factor 1.0

Hamburger Steak

*

0.8

0.6 0

120

240

360

Time (minutes) Pennings et al. Am J Clin Nutr 2013;98:121–8. Mince/ground meat is more quickly absorbed than steak

Faster Absorption Means Better Balance

Pennings et al Am J Clin Nutr 2013;98:121–8. More muscle is made and less broken down occurs when mince/ground meat is eaten compared to steak

Frequency of Protein Intake

Areta et al J Physiology 2013. The optimal protein dose given every 3/5 hours is optimal for maximizing protein synthesis after resistance exercise

Amino Acid Sensitivity

Burd et al J. Nutr. 2011, 141:568. Resistance exercise increases the MPS response to amino acids for at least 24 hours

Nightly Mixed Muscle FSR (%/h)

Protein Intake Before Sleeping *

0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 Placebo

Protein

Group Res et al Med Sci Sports Exerc. 44(8):1560-9. Consuming 40g of casein before bed increases protein synthesis overnight

Eating for Peak Muscle Growth

Amino Acid Intake and Muscle Hypertrophy • Proper nutrition is required for muscle hypertrophy and the maintenance of muscle mass. •In the fasted state both synthesis and degradation increase resulting in negative balance. • Essential amino acids (specifically essential amino acids like leucine) increase muscle protein synthesis and limit degradation. • The sensitivity of muscle to ingested amino acids is highest within the first 30 minutes but remains high for at least 24h following exercise.

Connective Tissue and Strength • Strength/power is directly related to connective tissue stiffness • Stiffness is increased by plyometric training rapid change of direction (Jerk) • As stiffness increases, the rate and degree of muscle injury increase • Stiffness is decreased through slow lengthening contractions this can be used to decrease and treat injuries

Stiffness and Strength/Power Change in Jump Height (cm)

8

*

6 4 2 0 CTL

Stiff

-2 -4 -6 -8

Group Foure et al (Scand J Med Sci Sports 19:811, 2009) and many others have shown that the higher the passive stiffness the higher the strength/power performance

Training for Performance Maximal Stiffness (kN/mm)

25

20

15

10

5

0 CTL

PT

Group Foure et al (Scand J Med Sci Sports 19:811, 2009). and others have shown that passive stiffness increases with plyometric training

Consequence of Stiffness Compliant Normal Stiff

Strength After Lengthening (% Control)

120 110

100

90

80

70

PRE

Day 1

Day 2

Day 3

McHugh et al (Amer J Sports Med 27:594, 1999) have clearly demonstrated that greater passive stiffness is related to injury.

Training to Decrease Stiffness

Mahieu et al (MSSE 40:117, 2007). show that 6-wk slow lengthening training results in a decrease in passive stiffness

Nutrition and Connective Tissue 9

Collagen (%)

8 7 6 5 4 3 2 1 0 CTL

AA+Pro

Treatment Paxton et al Tissue Eng Part A. 2010 Nov;16(11):3515-25. Ascorbic acid (vitamin C) and proline increase collagen synthesis in vitro

Tendon Development/Turnover 14C Content (pMC)

160

140 Sample Collection 120

100

80 1940

1960

1980

2000

Birth Year Heinemeier et al (FASEB J 2013) Tendon collagen doesn’t turnover after age 17 so optimize it early

Connective Tissue Summary 1. Slow lengthening contractions are optimal for improving/maintaining connective tissue health. Incorporating slow lengthening contractions into a rehab/prevention program can decrease time away from sport 2. Stiff connective tissues are ideal for speed, strength, and power. Increased stiffness results from plyometrics, but lead to increased instances of muscle injury 3. Following forced inactivity, tendons lose their compliance near the muscle end making the muscle more prone to injury 4. Adding gelatin and vitamin C to the diet 30-60 minutes before training improves collagen synthesis. Whey protein is also beneficial. 5. Genetic polymorphisms can be used to identify individuals with a propensity for injury and alter their training

Practical Summary 1. Strength/speed/power are determined by the size of the muscle, its activation, and the stiffness of the connective tissue. 2. The size and strength of a muscle is increased by lifting heavy weights to failure. 3. To maximize the response to training, an athlete should eat 0.25g/kg body weight protein in a rapidly digestible, high available leucine, form soon after ResEx and every 4-5 hours throughout the day. Twice that amount should be taken right before bed. 4. To increase strength/power performance, rapid plyometric type exercises performed in short bouts with 6h rest are ideal to increase connective tissue stiffness. However, this will increase the likelihood of injury. 5. Consuming foods rich in proline and vitamin C 30-60 min before exercise can help the synthesis of new collagen within connective tissue, decrease injury and improve recovery.

Further Reading 1.

Stuart Phillips – –

2.

Luc van Loon –

3.

Tipton et al AJP:Endo 276:E628, 1999.

Our lab -

5.

Res et al Med Sci Sports Exerc. 44(8):1560-9.

Kevin Tipton –

4.

Moore et al Am J Clin Nutr. 2009, 89:161. Tang et al J Appl Physiol 107: 987–992, 2009

Paxton et al Tissue Eng Part A. 2010 Nov;16(11):3515-25. Hagerty et al. Biomaterials 2012 Sep;33(27):6355-61. Paxton et al. TisEng 2012 Feb;18(3-4):277-84.

Michael Kjaer -

Heinemeier et al FASEB J. 2013 May;27(5):2074-9. Matrix Biol. 2013 Sep 28. pii: S0945-053X(13)00128-5. Scand J Med Sci Sports. 2013 Oct;23(5):614-9.