1. Musculoskeletal & Biomechanical Adaptations to Training HPER 6310 Dr. Suzan Ayers Western Michigan University

2. Lecture Overview Effects of Physical Activity on: bone bone joints and ROM joints and ROM muscle-tendon units muscle-tendon units body size, shape & composition body size, shape & composition Biomechanical Adaptations to Training: muscular muscular neuromuscular neuromuscular Biomechanical Adaptations to Injury

3. Physical Activity & Bone Disuse results in osteopenia (bone loss) Disuse results in osteopenia (bone loss) Genetically determined baseline mass for normal function (certain level of PA to ↔ bone health) Genetically determined baseline mass for normal function (certain level of PA to ↔ bone health) ↓ PA=bone loss, ↑ PA=bone growth (see below) ↓ PA=bone loss, ↑ PA=bone growth (see below) Weight-bearing PA= bone growth Weight-bearing PA= bone growth Too much intense PA problematic; optimal levels exist for each individual Too much intense PA problematic; optimal levels exist for each individual

4. Physical Activity & Joints/ROM Short-term effects of cyclical exercise (bike, run) Short-term effects of cyclical exercise (bike, run) Articular cartilage thickens (improved force dissipation) Articular cartilage thickens (improved force dissipation) 2-3x ↑ in volume of synovial fluid in a joint (lubricant) 2-3x ↑ in volume of synovial fluid in a joint (lubricant) Evidence supports endurance exercise’s benefits over sprint training on ligament strength Evidence supports endurance exercise’s benefits over sprint training on ligament strength Degenerative joint disease (osteoarthritis) Degenerative joint disease (osteoarthritis) Thinning articular cartilage Thinning articular cartilage Thickening compact bone under articular cartilage Thickening compact bone under articular cartilage Possible genetic, aging & environmental factors impact DJD dev’t Possible genetic, aging & environmental factors impact DJD dev’t Regular runners do NOT have > incidence of osteoarthritis HMMMM… Regular runners do NOT have > incidence of osteoarthritis HMMMM…

5. Physical Activity & Muscle-Tendon Units Physical Activity & Muscle-Tendon Units Flexibility: The ability to move a joint through its complete range of motion (ROM) (ACSM, 2000) Flexibility: The ability to move a joint through its complete range of motion (ROM) (ACSM, 2000) depends on muscle-tendon units crossing joints depends on muscle-tendon units crossing joints is joint-specific is joint-specific ↑ flexibility related to ↑ extensibility of connective tissue ↑ flexibility related to ↑ extensibility of connective tissue strength and flexibility training can promote ↑ ROM strength and flexibility training can promote ↑ ROM Laxity: The degree of abnormal motion of a given joint (Heyward, 2002) Laxity: The degree of abnormal motion of a given joint (Heyward, 2002) ↑ injury risk ↑ injury risk Hypermobility: Excess ROM at a joint (Heyward, 2002) Hypermobility: Excess ROM at a joint (Heyward, 2002)

6. Active Active Self-stretching Self-stretching Passive Passive Partner provides force of stretch Partner provides force of stretch Static Static Slow, sustained stretch held for 10-30 sec Slow, sustained stretch held for 10-30 sec Preferred in Physical Education settings Preferred in Physical Education settings PNF (Proprioceptive Neuromuscular Facilitation) PNF (Proprioceptive Neuromuscular Facilitation) Combo active/passive techniques Combo active/passive techniques NOT for children 6-10 yrs NOT for children 6-10 yrs Ballistic/Dynamic Ballistic/Dynamic Quick movements, bouncing, using momentum Quick movements, bouncing, using momentum Reserve for those 15 + yrs Reserve for those 15 + yrs Helpful to prepare athletes for competition Helpful to prepare athletes for competition

7. Static stretches should be held to the point of mild discomfort Static stretches should be held to the point of mild discomfort “No pain, no gain” is INAPPROPRIATE! Training principles Training principles Frequency: Daily (min 3x/wk) Frequency: Daily (min 3x/wk) Intensity: To point of mild discomfort Intensity: To point of mild discomfort Time: 10-30 sec Time: 10-30 sec Type: Static, PNF, partner, etc. Type: Static, PNF, partner, etc.

8. Strength changes Weeks 6-8 primarily neuromuscular Weeks 6-8 primarily neuromuscular Weeks 9 + gains due to ↑ fiber size/volume Weeks 9 + gains due to ↑ fiber size/volume Long-term benefits Long-term benefits Fiber changes resulting in improved fatigue-resistance Fiber changes resulting in improved fatigue-resistance ↑ relative amount of connective tissue ↑ relative amount of connective tissue Tendon Adaptations Much slower rate of adaptation than muscle Much slower rate of adaptation than muscle Collagen synthesis ↑ Collagen synthesis ↑ Fibers align more regularly longitudinally Fibers align more regularly longitudinally Muscle strains often occur @ junction of tendon and muscle Muscle strains often occur @ junction of tendon and muscle

9. Endomorph relaxed, sociable, tolerant, comfort-loving, peaceful, plump, buxom, developed visceral structure Mesomorph active, assertive, vigorous, combative, muscular Ectomorph quiet, fragile, restrained, non-assertive, sensitive, lean, delicate, poor muscles Physical Activity’s Effect on Body Size, Shape & Composition

10. EndomorphMesomorph Ectomorph Dr. William Sheldon’s “somatotypes”

11. Somatotype challenge In the 1940s, Dr. William Sheldon (1898-1977) proposed a theory about how certain body types ("somatotypes") are associated with certain personality characteristics. He claimed that there are three such somatotypes: endomorphy, mesomorphy, and ectomorphy. You can rate yourself on each of these three dimensions using a scale from 1 (low) to 7 (high) with a mean of 4 (average). Therefore, a person who is a pure mesomorph would have a score of 1-7-1. A pure endomorph would be 7-1-1. A pure ectomorph would score a 1-1-7. A mostly average person who has some endomorphic tendencies would have a score of 6-4-4... etc. Rate the degree to which you think you possess each of the three body types.

12. Endomorphic Body Type soft body soft body underdeveloped muscles underdeveloped muscles round shaped round shaped over-developed digestive system over-developed digestive system Associated personality traits: love of food love of food tolerant tolerant evenness of emotions evenness of emotions love of comfort love of comfort sociable sociable good humored good humored relaxed relaxed need for affection need for affection

13. Mesomorphic Body Type hard, muscular body hard, muscular body overly mature appearance overly mature appearance rectangular shaped rectangular shaped thick skin thick skin upright posture upright posture Associated personality traits: adventurous adventurous desire for power and dominance desire for power and dominance courageous courageous indifference to what others think or want indifference to what others think or want assertive, bold assertive, bold zest for physical activity zest for physical activity competitive competitive love of risk and chance love of risk and chance

14. Ectomorphic Body Type thin thin flat chest flat chest delicate build delicate build young appearance young appearance tall tall lightly muscled lightly muscled stoop-shouldered stoop-shouldered large brain large brain Associated personality traits: self-conscious self-conscious preference for privacy preference for privacy introverted introverted inhibited inhibited socially anxious socially anxious artistic artistic mentally intense mentally intense emotionally restrained emotionally restrained

15. Lifestyle Factors ↑ PA while ↓ caloric intake=fat loss ↑ PA while ↓ caloric intake=fat loss Training can make physiological changes at any age (it’s never too old to teach an old dog new tricks Training can make physiological changes at any age (it’s never too old to teach an old dog new tricks Height is genetically predetermined Height is genetically predetermined Weight can be altered to a given genetic point Weight can be altered to a given genetic point Somatotype can change as strength and endurance requirements change Somatotype can change as strength and endurance requirements change

16. Biomechanical Training Adaptations Training influences both contractile properties of muscle (strength, speed) and neural control (coord.) Training influences both contractile properties of muscle (strength, speed) and neural control (coord.) Strength changes due to Strength changes due to ↑ net neural drive to muscle (motor unit recruitment) ↑ net neural drive to muscle (motor unit recruitment) ↑ muscle size ↑ muscle size both neural and structural changes both neural and structural changes Contraction speed changes due to Contraction speed changes due to Δ in shape of muscle’s force-velocity curve Δ in shape of muscle’s force-velocity curve Δ in value of the intrinsic max shortening velocity Δ in value of the intrinsic max shortening velocity both shape and max shortening velocity changes both shape and max shortening velocity changes

17. Muscular Training Adaptations Max force produced depends on length of muscle during contraction Max force produced depends on length of muscle during contraction Initial strength gains (wk 2-8) primarily neural Initial strength gains (wk 2-8) primarily neural 10 + wk gains primarily hypertrophic 10 + wk gains primarily hypertrophic Isokinetic training can change force-velocity curve Isokinetic training can change force-velocity curve Contraction speed changes also influence force- velocity curve shape, ergo power Contraction speed changes also influence force- velocity curve shape, ergo power (strength x speed = power)

18. Neuromuscular Training Adaptations Incidence of serious knee injury 6x F>M athletes Intrinsic risk factors for ACL injury Intrinsic risk factors for ACL injury Lower extremity malalignment Lower extremity malalignment ↓ intercondylar notch width at the knee ↓ intercondylar notch width at the knee ↑ knee joint laxity ↑ knee joint laxity Hormonal influences (Relaxin) Hormonal influences (Relaxin) Extrinsic risk factors for ACL injury Extrinsic risk factors for ACL injury Imbalanced quad/ham strength Imbalanced quad/ham strength Inadequate neuromuscular control Inadequate neuromuscular control GOAL: improve stability (balance, coordination), proprioception, & strength

19. ACL injury-prevention neuromuscular programs Knee stability/function improve with ↑ in postural equilibrium, intermuscular control & leg muscle strength Knee stability/function improve with ↑ in postural equilibrium, intermuscular control & leg muscle strength Means of ↑ aforementioned factors: Means of ↑ aforementioned factors: Stretching Stretching Plyometric exercises (AKA, jump training) Plyometric exercises (AKA, jump training) Weight lifting Weight lifting Evidence supporting neuromuscular training’s role in ↓ incidence of sport-related knee injuries Evidence supporting neuromuscular training’s role in ↓ incidence of sport-related knee injuries Ham:Quad strength ratio key to ACL injury prevention Ham:Quad strength ratio key to ACL injury prevention Neuromuscular training can ↑ knee joint stability Neuromuscular training can ↑ knee joint stability ↑ H:Q ↑ H:Q Fine-tune neural control over hamstrings Fine-tune neural control over hamstrings