Exercise Science

• Periodization 
  • strength and conditioning term for planned variation in intensity and duration of a specific workout over a predefined duration of time
• Dynamic exercise improves cardiac output by increasing cardiac stroke volume 
• Endurance (aerobic) Training
  • results in changes in circulation and muscle metabolism
  • contractile muscle adapts by increasing energy efficiency
  • increases in mitochondrial size, number, and density
  • increases in enzymes involved in Krebs cycle, fatty acid processing, and respiratory chain
  • over time, increased use of fatty acids > glycogen
  • over time, oxidative capacity of Type I, IIA, and IIB fibers increase
    • percentage of more highly oxygenated IIA fibers increases
  • Aerobic Threshold: level of effort at which anaerobic energy pathways become significant energy producer
  • Anaerobic (lactate) Threshold: level of effort at which lactate production > lactate removal
• Strength Training
  • typically high-load, low-repetition activities
  • results in increased cross-sectional area of muscle due to muscle hypertrophy
    • hyperplasia (increased number of fibers) less likely
  • results in increased motor unit recruitment +/- improved synchronization of muscule activity
  • maximal force production is proportional to muscle physiologic cross-sectional area
  • adolescents can safely participate in appropriate strength training programs 
    • gains in strength largely due to improved neuromuscular activation and coordination rather than muscle hypertrophy
    • gains for adolescents are reversible if training is discontinued

• Benefits 
  • decreases joint stress by lowering vertical component of the ground reaction force through buoyancy  
  • unique advantages in cardiorespiratory fitness when compared to land training
  • less abrupt increases in heart rate
  • increased oxygen consumption
  • prevents secondary injuries to the lower limb

• Commonly mistaken for exercise-induced bronchoconstriction in athletes
• Epidemiology
  • gender - more common in females
• Mechanism - unknown
• Symptoms
  • dyspnoea
  • wheezing
• Differential diagnoses
  • exercise-induced bronchoconstriction (EIB, or exercise-induced asthma)
  • hyperventilation
  • cardiac conditions
• Diagnosis
  • negative bronchodilator reversibility test (with beta2-agonist)
    • positive in EIB
  • negative bronchoprovocation tests (e.g. methacholine challenge, mannitol challenge, eucapnic voluntary hyperventilation test)
    • positive in EIB
  • positive continuous laryngoscopy during exercise (CLE)
• Types (anatomic location)   
  • supraglottic level
  • glottic level
• Treatment
  • optimum treatment is being investigated

Exercise-Induced Hematuria

• Epidemiology
  • Incidence
    • Microscopic hematuria present in 16.7 - 46.7% of athletes
    • Macroscopic hematuria present in 3.1 - 19.2% of athletes
  • Risk Factors
    • Exercise intensity
    • Posture
    • Age
    • Heat load
    • Altitude
    • Pre-existing kidney disease
• Pathophysiology
  • Proposed pathophysiology of exercise-induced hematuria
    • Bladder/kidney contusion from up and down motion 
    • Vascular spasm to kidney 
• Presentation
  • History
    • Presence of hematuria correlates with increased exercise intensity
  • Symptoms
    • Asymptomatic
• Differential
  • Urinary tract infection or Sexually transmitted infection
    • Pyuria and dysuria
  • Papillary necrosis
    • Personal or family history of Sickle cell trait or disease
  • Kidney Contusion
    • Blunt impact to flank and flank pain
  • Kidney Stone
    • Dysuria and flank pain
• Treatment
  • Nonoperative
    • Cessation of exercise, repeat urinalysis in 48-72 hours  
    • Further workup indicated if:
      • Hematuria persists >7 days after cessation of exercise
      • Age >50

• Effects on muscles
  • increased cross-sectional area
  • increased strength
  • increased mitochondria
  • increased capillary density
  • thickened connective tissue
• Adult strength gains are associated with muscle hypertrophy
• Adolescent strength gains occur more from increased muscle firing efficiency and coordination

• Carbohydrate loading 
  • involves increasing carbohydrates three days prior to an event and decreasing physical activity to build up carbohydrates stores
  • increases the stores of muscle glycogen to provide improved endurance, especially in events lasting > 90 minutes when the bodies normal supply of glycogen runs low
  • best technique for athlete is to instead maintain normal diet
• Fluid loading and replacement
  • magnitude of core temperature and heart rate increase accompanying work are proportional to the magnitude of water debt at the onset of exercise 
  • best technique is to replace enough water to maintain prepractice weight
• Fluid carbohydrate and electrolyte replacement
  • best done with low osmolarity (< 10%) fluids of carbohydrates and electrolyties which enhances absorption in the gut
    • glucose polymers decrease osmolarity

• Muscles soreness
  • caused by edema and inflammation in the connective tissue
    • leads to increased intramuscular pressure
    • occurs primarily in Type IIB fibers
  • worse with unaccustomed eccentric exercise
  • often with delayed onset: Delayed-Onset Muscle Soreness (DOMS) 
    • peaks at 24-72 hours
  • elevated CK levels seen in serum
• Muscles strain
  • occurs commonly at myotendinous junction (often during eccentric contraction which produces highest forces in skeletal muscle)
  • pathoanatomy in inflammation followed by fibrosis
• Muscle contusion
  • non-penetrating blunt injury
  • leads to hematoma and inflammation
  • extracellular connective tissue forms within 2 days, peaks between 5-21 days
  • healing characterized by late scar formation, variable muscle regeneration
  • myositis ossificans (bone formation within the muscle tissue) 
    • most apparent 4 weeks post-injury
• Muscle laceration (complete tear) 
  • typically occur near myotendinous junction
  • characterized by abnormal muscle countour
  • fragments heal by dense connective scar tissue
    • mediated by myofibroblasts
      • TGF-beta stimulates differentiation and proliferation of myofibroblasts 
  • regeneration and renervation: unpredictable and likely incomplete

• Can result in shorter muscle position and atrophy
• Leads to decreased ability to generate tension and increased fatigability
• Results in fatty infiltration
• Atrophy occurs faster in muscles crossing a single joint
• Atrophy occurs at a non-linear rate
  • most changes occur during initial days of disuse
  • seen at cellular level: loss of myofibrils within the fibers
  • related to duration of immobilization
• Atrophy is more prominent if immobilization occurs without tension
  • quadriceps atrophy greater than hamstrings with knee immobilization in extension

• Local treatments designed to assist with soft tissue recovery or rehabilitation
• Goals of treatment
  • decrease inflammation
  • increase local blood flow
  • increase tissue compliance
• Modalities include
  • cryo or heat treatments
  • massage
  • ultrasound
  • electrical stimulation
  • Iontophoresis  
    • use of an electrical current to drive charged molecules of medicine through the skin to the deep tissues
    • medications including steroids, local anesthetics, salicylates, and non-steroidal anti-inflammatory drugs (see table below)
    • indications - see table below
    • contraindications
      • susceptibility to applied currents e.g. cardiac pacemakers
      • hypersensitivity/allergy to drug used