EXCI 252

• Muscular Fitness


  Refers collectively to the characteristics of strength, hypertrophy, power, and local muscular endurance
• Muscular Fitness


  • Is optimized through the implementation of resistance training, which can encompass free weights, machines, body weight, bands/tubing, or any other object that requires one to exert force against a resistance
• Muscular Endurance


  Also called local muscular endurance, is the ability of a muscle group to exert a submaximal force for extended periods, maintain a specific % of the maximum voluntary contraction (MVC) for a prolonged period of time, execute repeated contractions over a period of time sufficient to cause muscular fatigue, or exert submaximal force repeatedly, or sustain a static contraction without fatigue
• Muscular Strength


  Is the maximal force generated in a single contraction at a specified velocity, the ability of a muscle group to develop maximal contractile force against a resistance in a single contraction, refers to the maximal force that can be generated by a specific muscle or muscle group, and is the peak force or torque developed during a maximal voluntary contraction (MVC)
• Muscular Power


  Is a skill-related component of physical fitness, the muscle's ability to exert force per unit of time, the ability to exert force rapidly, the rate at which mechanical work is performed, and the maximal amount of force one can exert in the least amount of time
• Types of Muscle Action

  • Isometric or Static Muscle Action: same muscle length, no visible movement of the joint

  Dynamic Muscle Action: muscle length changes, visible joint movement, auxotonic, isokinetic, or variable resistance

  Isotonic Muscle Action: traditional term used to describe the muscle action when lifting free weights, is a misnomer because the tension produced by a muscle group during free weight exercise fluctuates greatly even though the resistance is constant throughout the range of motion (ROM)

  Auxotonic Muscle Action: is defined as variable muscle tensions caused by changing velocities & joint angles, is the correct term for describing the muscle action when lifting free weights or performing resistance exercise with a constant resistance exercise machine, can be either concentric or eccentric
• Auxotonic Muscle Action


  • Concentric Muscle Action: resistance < force produced by muscle group, muscle shortens during tension development, e.g. weight is lifted

  Eccentric Muscle Action: resistance > force produced by muscle group, muscle lengthens during tension development, resist gravity, braking force to decelerate rapidly moving body segments, greater risk of injury, e.g. weight is lowered
• Isokinetic Muscle Action


  Is a maximal contraction of a muscle group at a constant velocity throughout the entire range of joint motion, can only be performed on an isokinetic-resistance exercise machine called an isokinetic dynamometer
• Purposes of Strength & Muscular Endurance Assessment

  • Establish baseline values before training

  Monitor progress during training

  Assess the overall effectiveness of resistance training & exercise rehabilitation programs
• Tests that Assess Strength & Muscular Endurance are Specific to the:

  • Muscle or Muscle Group Tested

  Type of Muscle Action: Static or dynamic muscle action

  Velocity of Muscle Movement: Slow or fast movement

  Type of Test: Strength or endurance test

  Type of Equipment: Free weights, constant-resistance exercise machines, variable-resistance exercise machines, or isokinetic-resistance exercise machines

  Joint's Range of Motion (ROM): Static or dynamic muscle action
• Absolute Muscular Strength


  MVC in Newtons or kg
• Relative Muscular Strength


  MVC / Body Mass
• Isometric Muscle Testing


  • Spring-Loaded Dynamometers

  Handgrip Dynamometer

  Back & Leg Dynamometer

  Hydraulic Dynamometers

  Cable Tensiometers

  Digital Handheld Dynamometer

  Clinical Methods

  Load Cells (Strain Gauges)
• Isometric Muscular Strength


  Is measured as the maximum force exerted in a single contraction against an immovable resistance (i.e., maximum voluntary contraction, or MVC), and is the maximal force produced by a muscle group when the limb is not rotating (zero velocity)
• Spring-Loaded Dynamometers


  • An external force applied to the dynamometer compresses a steel spring & moves an indicator needle or pointer, the force required to move the pointer a given distance determines the external force applied to the dynamometer
• Spring-Loaded Handgrip Dynamometer


  Measures forces from 0 to 100 kg in 1.0-kg increments
• Handgrip Strength Testing


  • Handgrip Strength is a measure of isometric strength, is a widely used indicator of total body strength, has been shown to be predictive of functional limitations and disability later in life, and was a stronger predictor of all-cause and cardiovascular mortality than systolic blood pressure in a large longitudinal population study conducted in 17 countries (Leong et al., 2015)
• Handgrip Strength Testing Procedures

  • Protocol 1 (ASHT, 1992): Seated or stand erect, shoulder adducted & neutrally rotated, elbow of test arm is flexed at 90o, forearm in neutral position, slight wrist extension 0 to 30o, 3 trials per hand, record the mean of 3 trials

  Protocol 2 (CSEP, 2021): Stand erect, arm slightly abducted in a neutral position, test arm is straight, 2 trials per hand, alternating hands, record maximum score for each hand to the nearest 1 kg, combine the maximum scores from the left & right hands
• Spring-Loaded Back & Leg Dynamometer

  Measures forces from 0 to 1,134 kg in 4.5-kg increments
• Leg & Back Strength Testing Procedures

  • Leg Strength: Stand on platform, erect trunk, flexed knees (130o - 140o), pronated grip on hand bar, slowly exert as much force as possible while extending the knees without using the back, 2 or 3 trials, 1 min rest between trials, choose MAX score & convert it to kg

  Back Strength: Stand on platform, head & trunk erect, knees fully extended, alternated grip (right hand = pronated, left hand = supinated), pull the hand bar straight upward using the back muscles without leaning backward, 2 trials, 1 min rest between trials, choose MAX score & convert it to kg
• Handgrip Endurance Testing Procedures

  • Maximal Force (MVC): Squeeze the handle maximally for 1 minute, record the initial & final forces

  Submaximal Force (% MVC): Squeeze the handle at a submaximal force for as long as possible, Relative endurance score = (Final force / Initial force) x 100, Relative endurance score = time that the %MVC is maintained
• Hydraulic Dynamometers


  Are an alternative to spring-loaded dynamometers that can be used to measure isometric grip strength, have a sealed hydraulic system that measures force (lb or kg) on a gauge dial, example: Jamar handgrip dynamometer
• Jamar Handgrip Dynamometer


  • Is widely used & has excellent validity & reliability, is widely regarded as the gold standard for handgrip dynamometers among clinicians, may not be appropriate to measure isometric strength for individuals with a weak MVC because the resolution of the device is too large to detect small changes in strength
• Myogrip Dynamometer (Hogrel, 2015)


  Is recommended for clients with a weak MVC
• Cable Tensiometer


  Is an instrument that measures force in an isometric muscle action, provides the advantage of versatility for recording force measurements at virtually all angles about a specific joint's ROM, can be used to assess static strength of 38 different muscle groups throughout the body, increasing the force on the cable depresses the riser over which the cable passes, this deflects the pointer & indicates the subject's strength score
• Cable Tensiometer Instrumentation


  • Tensiometer

  Steel cables

  Testing table

  Wall hooks

  Straps

  Goniometer
• Cable Tensiometry Tests


  • Can be used to assess strength impairment at specific joint angles, monitor progress during rehabilitation
• Clinical Methods


  • V-Sit Test
• Strength score


  Indicates the subject's strength
• Cable Tensiometer Instrumentation


  • Tensiometer
  • Steel cables
  • Testing table
  • Wall hooks
  • Straps
  • Goniometer
• Cable Tensiometry Tests


  • Can be used to assess strength impairment at specific joint angles, monitor progress during rehabilitation
• Digital Handheld Dynamometry


  Convenient method for measuring the isometric strength of the upper & lower body musculature, provides a digital display of force production to assess the isometric strength of 11 muscle groups
• Clinical tests to measure the isometric endurance of core muscles used to stabilize the spine

  • V-Sit Test - trunk flexors
  • Sorensen Test - trunk extensors
  • Side Bridge Test - lateral flexors
• 1. Sit Test, Sorensen Test, Side Bridge Test


  • Trunk is reclined 60o, Knees & hips flexed 90o, Bench height = 25 cm, Novel Side-Support Test with feet elevated on a 15-cm padded stool
• Methods to test dynamic muscular strength & endurance

  • Free Weights
  • Constant-Resistance Exercise Machines
  • Variable-Resistance Exercise Machines
  • Free-Motion Exercise Machines
  • Isokinetic-Resistance Exercise Machines
  • Calisthenic-Type Exercise Tests
• Auxotonic Dynamic Exercise


  Also called dynamic constant external resistance (DCER) exercise, where the muscle group does not contract maximally throughout the ROM
• Auxotonic Dynamic Exercise


  • Major Disadvantage: They measure dynamic strength only at the weakest point in the ROM, as the resistance cannot be varied to account for fluctuations in muscular force caused by changing mechanical & physiological advantage of the musculoskeletal system during the movement
• Advantages & Disadvantages of Constant-Resistance Exercise Machines Compared to Free Weights

  • Advantages: Require less neuromuscular coordination to stabilize body parts & maintain balance, Do not require spotting
  • Disadvantages: Limit an individual's ROM & plane of movement, Have relatively large weight plate increments, Cannot accommodate individuals with short limbs, long limbs, a large body, & large limb circumferences
• Dynamic Muscular Strength Testing

  • Force Plates + Linear Transducers
  • Tendo Weightlifting Analyzer System
  • Myotest Accelerometer
  • 1-Repetition Maximum (1-RM)
  • Estimation of 1-RM
  • Relative strength: 1-RM / Body Mass
• Force Plates + Linear Transducers

  • Used to obtain direct measures of muscular force & power, the gold standard of measuring dynamic muscle strength & power, are expensive due to cost of equipment, used in a laboratory setting