Strength and Conditioning for Power and Strength Sports: Science to Application

Transcription

1 Strength and Conditioning for Power and Strength Sports: Science to Application William J. Kraemer, Ph.D., CSCS*D FACSM, FNSCA, FISSN, FACN Human Performance Laboratory University of Connecticut Storrs, CT USA

2 The Science Is intimately LINKED to Practice and Application

3 Strength and Power Training

4 Do we not already know how to train these things?

5 The key to this lecture is to understand the impact and meaning of the loading used in a strength and power training program! What do the sets and reps and loads you choose to program. mean to the body s physiological function?

6 What doest this mean?

7 Definitions Strength maximal force that can be generated in a movement at a given velocity Power Velocity Component 1 RM

8 Strength and Power are important for every athlete.but demands for context vary.for its expression.

9 Upstream Regulatory Elements Exercise Stimuli Nutrition Environment Psychology STIMULI Neural Activation Resistance to Aerobic D O W N S T R E A M Physiological Systems Cardiovascular, Endocrine, Immune, etc Organs Tissues Receptors Cells and Cell Signaling ADAPTATION Gene Interactions, Expression and Protein Synthesis FITNESS

10 What are the major factors that dictate maximal strength Number of muscle fibers Type of muscle fibers Cross-sectional area of a muscle is related to maximal force production

11 Each athlete brings an individual profile and physiological capability to the sport but this is also related to training potential and needs in strength and power

12 Body somatotype will influence gains in strength and size development

13 Starting body type will influence lean muscle tissue gain with heavy resistance training! Women = N = 14 in a group 6 months of training * # $ Delta Change in Thigh Muscle Size 5 0 Ecto Meso Endo

14 Starting body type will influence lean muscle tissue gain with heavy resistance training! Women = N = 14 in a group 6 months of training * # $ Ecto Meso Endo Delta Change in Upper Arm Muscle Size

15 Importantly a training stimulus for muscular strength and power starts with.. First Step = Muscle Activation Only those motor units that are activated will ultimately benefit from exercise training

16 Henneman s Size Principle A major governing principle that dictates the activation of motor units and associated fibers. Elwood Henneman Henneman E, Somjen G, and Carpenter DO. Functional significance of cell size in spinal motoneurons. J Neurophysiol 28: , 1965

17 Motor Unit: An alpha motor neuron and all of the muscle fibers it innervates Alpha Motor Neuron AXONS Motor END PLATE Muscle Fibers

18 Physiological profiles of motor units: All fibers in a motor unit are of the same fiber type! Slow (Type I) motor units contain slow fibers: Myosin with long cycle time and therefore uses ATP at a slow rate. Many mitochondria, so large capacity to replenish ATP. Economical maintenance of force during isometric contractions and efficient performance of repetitive slow isotonic contractions. Fast (Type II) motor units contain fast fibers: Myosin with rapid cycling rates. For higher power or when isometric force produced by slow motor units is insufficient. Type 2A fibers are fast and adapted for producing sustained power. Type 2X fibers are faster, but less-oxidative and fatigue rapidly. 2X not 2B. Burke, R.E. et al, J. Physiol.

19 Size Principle HIGH High Force 1 RM Activation Threshold LOW 20 RM Power 15 RM 10 RM 5 RM Motor Unit Type I Type II LOW Force Production HIGH

20 Activated Tissue Tissue not activated with not adapt to the training program Lighter pixels represent activation in the squat exercise MRI ANALYSES Ploutz et al. Physiologist, 1995

21 Size Principle Two Recruitment Types: 1. Synchronous: patterned recruitment up the line to greater and greater force 2. Asynchronous: Used when force is lower and more endurance activities predominate.

22 Size Principle LIGHT RM Moderate 8-10 RM Heavy 3-5 RM NON-ACTIVATED ACTIVATED

23 Training Pre-Training POST-Training ACTIVATED NON-ACTIVATED With training force is consolidated to a smaller area to increase the amount of force per cross-sectional area leaving the remaining tissue non-activated. BASIS FOR PERIODIZATION OF TISSUE TRAINING

24 Motor Units Activated Are Trained!

25 Every time you change an exercise angle you change the exercise! Thus the specificity of the exercises in a program dictate where the strength and power changes will occur

26 However Activation starts in the BRAIN

27 Discovery: We found in our laboratory that cortical responses are sensitive to protocols Protocol Sets Reps per Set Load PWR % 1RM FOR % 1RM VOL % 1RM CTRL 6 N/A 15 lbs (bar)

28 We study behaviorally-relevant movements 1 Repetition

29 The future: a growing appreciation for the brain s role in performance and recovery Squat at 95% MDVC Squat at 80% MDVC Squat jump at 30% MDVC Brain activity and acute program variables Flanagan B, Brain Sciences 2012 from our laboratory Control

30 Acute program variables (APVs) represented in cortical activity Global motor activity increases with fatigue; APV-specific

31 We also know that Local cortical functions are sensitive to exercise-induced muscle damage - Increased somatosensory and prefrontal cortical activity with muscle damage and pain Contro l Exercise Sig Diff

32 In the press the people still think that lifting light to failure will be as good as lifting heavy weights Reporting on one study. 80% of 1 RM was as good as 30% of 1 RM for ten weeks of knee extension training Huffington Post March 2014

33 Squat Exercise Our recent study again contexts this assertion. So does going to failure make the difference?

34 1 st Rule for Training for Maximal Strength Heavy lifting with loads greater than 90% of 1 RM need to be included in a program for major muscle groups! Some truth in this statement for major muscle groups. Yet.

35 Size Principle HIGH Activation Threshold LOW High Force 1 RM Train this area one can get increases in 1RM in untrained people due to contribution of hypertrophy in these motor units but this Power stops very quickly 5 RM and leads to a plateau 10 RM Motor Unit Type I 15 RM Type II 20 RM LOW Force Production HIGH

36 Key Concept: Different mechanisms will be brought into play to support the activation of motor units to perform the external force function required by the activity.

37 Number of motor units declines during aging - extensor digitorum brevis muscle of human beings AGE-ASSOCIATED ATROPHY DUE TO BOTH Individual fiber atrophy (which may be at least partially preventable and reversible through exercise). Loss of fibers (which as yet appears irreversible). Campbell et al., (1973) J Neurol Neurosurg Psych 36:

38 Motor unit remodeling with aging Central nervous system Muscle Motor neuron loss AGING Fewer motor units

39 Motor Unit Array in a Muscle Varies for Individuals and Muscles abdominal (postural muscles) Type I motor units Locomotor Muscles Type I Type II Motor Units

40 SIZE PRINCIPLE Recruitment threshold HIGH Power 1-5 RM 6-10 RM LOW RM 71% Type II Strength Power Athlete Low Force Production High

41 Recruitment threshold SIZE PRINCIPLE 80 Year old women Vastus Lateralis HIGH No Type II muscle fibers Compressed Motor Unit array Type I motor Unit LOW Low Force Production High

42 SIZE PRINCIPLE Recruitment threshold Endurance Athlete Vastus Lateralis HIGH LOW Type I Motor Unit 80% Type I muscle Fibers Low Force Production High

43 Skeletal Muscle Fibers Types II XA II A I II X Myosin ATPase stain, ph 4.6 from Dr Kraemer s Laboratory

44 In Young Men Fiber Hypertrophy % Increase in CSA RM 8-10 RM RM 0 Type I Type IIA

45

46 So.why cannot light weights develop type I muscle fibers as well as heavy?

47 It is the Hz through the recruitment path! heavy High Hz Light Low Hz

48 Factors that Influence of Training on Skeletal Muscle Fibers Characteristic Number of Muscle Fibers Type of Muscle Fibers Impact on Training Limits absolute size of intact muscle Impacts function and repair and recovery Type I Type II Are made up of heavy protein bands (e.g., Z lines, non-contractile proteins), made for repeated activation, peak force low Light protein bands, higher amounts of contractile proteins, made for intermittent activation, high peak force

49 Fiber Growth Characteristics Type I Muscle Fibers Type II Muscle Fibers Emphasis on the reduction in degradation of muscle proteins with less emphasis on synthesis Rapid attainment of cell size maximum and resistance to muscle size gains Emphasis on the increase in protein synthesis and less importance on the reduction of degradation of muscle proteins Explains some Type II preferential cell hypertrophy

50 Heavy Loading Workouts Placed within a periodized program Linear Non-Linear Forced Reps Some efficacy in highly trained athletes Ahtiainen and Häkkinen JSCR 2009 Short Pyramids Set Training

51 .but it recovery must be allowed! Heavy Lifting Requires Long rest between sets 3-7 minutes Recovery from the heavy eccentric loading phase of the repetition Heavy lifting with the eccentric load provides a protective effect from further mechanical damage of the muscle cell

52 Explosive Power

53 Power Production Range Dependent on Type of Exercise (Specific) Long-Distance Runner (50 W /stride cycle) Weightlifter (10,000+ W during Clean)

54 REMEMBER The rate of performing work The product of force and velocity 1) Work = Force x Distance 2) Power = Work = force x distance T T 3) Power = Force x distance T

55 Improving Power Why not just work on strength (force) part of the equation?

56 Because Heavy loading only works on the FORCE part of the equation and when it tops off the changes in the whole force velocity curve is not affected.

57 Maximal Power Force heavy resistance strength training explosive strength training force at 200 ms untrained maximum strength maximum RFD Time (ms) 500

58 When training power choice of exercise is critical. Holding on to the weight in many exercises just promotes deceleration! Let gravity be what slows the mass down Olympic style lifts, plyometrics, pneumatics, hydraulics can tolerate explosive lifting for high velocity movements

59 Newton RU et al JAP EXERCISE 0.2 CHOICES CANNOT INVOLVE DECELERATION OF THE JOINT Velocity (m/s) Bench Press vs. Bench Throw Press EXCEPT FROM GRAVITY and thus one must release the mass or used exercises 0 where joint protection is not a problem e.g., Olympic Bar pulls, etc Throw Force (N) Percent of Bar Displacement 200

60 A.

61 Quality Repetitions for training POWER OUTPUT B Maximal Power Capability 90 % of 1 RM set of 1 set of 3 after practice 0 set 1 set 3 set 5 Cannot train maximal power when fatigued

62 Bench Throw: Max Mech Power Output Men: 30% 1RM Women: 30-50% 1RM

63 Hang Pull: Max Mech Power Output Both: 30-60% 1RM

64 Power Program More sets fewer reps per set to optimize power output and technique e.g., 6 sets of 2-3 at a load percentage. Exercises without deceleration component Train across the full forcevelocity curve

65 Threats to Strength and Power Development!

66 Compatibility simultaneous strength and endurance training Problem: potential to impede performance High-intensity aerobic training may inhibit strength and power adaptations important for performance

67 Compatibility of Programs Muscle Fiber Size Responses to Training MODE OF TRAINING TYPE I TYPE II ENDURANCE DECREASE No CHANGE STRENGTH TRAINING Increase Increase COMBINATION NO CHANGE Increase Kraemer et al. J. Appl. Physiology 1995

68 Extreme Conditioning Programs Done properly it can provide ONE type of metabolic training stimulus in a total conditioning program! However, typically targeted for High intensity local muscular endurance Body composition changes So called functional movements Done exclusively it LIMITS optimal development of other muscular fitness components such as power and strength due to the fatigue levels produced with short rest and high volume exercise

69 Extreme Exercise Programs are extremely stressful from a physiological perspective Metabolically High cardiovascular stress High anaerobic glycolytic stress (e.g., high lactate values with workouts) Stress hormone High adrenal stress with dramatically elevated cortisol and catecholamines after a workout High resting cortisol values Immune system Greater immune suppression after a workout Neuromuscular Higher oxidative damage and free radical formation.

70 Example: Resting Cortisol nmol/l 4000 Normal range 200 to 400 nmol/l Normal Training Extreme Resting

71 Extreme Exercise: Short Rest Circuit using moderate-heavy weights Heart Rates equal to maximal treadmill tests Lactic Acid Highest type workout concentrations Kraemer et al., IJSM 1987

72 Cortisol Eosinophils Lactic Acid Kraemer et al. Int J. Sport Med 1987

73 Epinephrine Norepinephrine = Immediately after a Max treadmill test Dopamine Kraemer et al. Int J. Sport Med 1987 and these data are 5 Minutes POST-Exercise

74 So what do we do????

75 Acute Program Variables Describe a single training session and determine acute physiological responses. Choice of Exercise Order of Exercise Intensity Volume Rest Periods Kraemer, WJ. NSCA Journal, 1983

76 Periodization Example Monday: Light Day. 2-4 sets, reps at RM Tuesday: Power Day. 3-4 sets, 2-4 reps at % 1RM Thursday: Moderate Day. 2-4 sets, 8-10 reps at 5-10% less Heavy Day Friday: Heavy Day. 3-4 sets, 3-6 RM

77 Resistance Training Exercise Prescription Biomechanical Analysis Needs Analysis Analysis of Metabolic Demands Injury Prevention Setting Program Goals Performance Function strength power endurance Athletic Function coordination, speed, agility, balance Injury Prevention fall prevention Tissue density Physiological Changes BP % BF metabolic rate Choices Individualization Evaluation Program Manipulation Acute Program Variables Choice of Exercise Order of Exercise Intensity Number of Sets Rest Period Lengths Kraemer, WJ, Fragala, MS. ACSM's Health & Fitness Journal. 10(4):7-17, July/August 2006.

78 Kraemer Laboratory Group the credit belongs to a team

79