4: Muscular Fitness: Strength and Endurance

Question 1

Muscle Strength

Answer 1

– Maximal amount of force a muscle can produce

Question 2

Muscle Endurance

Answer 2

– Ability of a muscle group to perform repeated contractions at a submaximal level

Question 3

Physiological Benefits of Good Muscular Fitness

Answer 3

– Improved bone mass (reduced risk of osteoporosis)
– Improved glucose uptake (better blood glucose control thus reduced risk of Type 2 diabetes
– Increased fat-free mass and resting metabolic rate (improved body composition and weight control)
– Improved ability to perform activities of daily living (ADL)
– Improved physical activity/sport performance
– Less risk of musculoskeletal injuries and low back pain
– Offset age-related changes in muscle (i.e. loss of muscle mass, strength and endurance)

Question 4

Why measure muscular strength/endurance

Answer 4

o Test upper body strength
o Test for muscle imbalance (eg. weak hamstrings – train hamstrings)
o Test in older people to note if strength is healthy/normal

Question 5

Factors to Consider for Assessing Muscular Strength and Endurance

Answer 5

o There are 700 skeletal muscles with varied performance levels.
– Therefore, there is no single measurement that provides an assessment of an individual’s muscular strength or muscular endurance.

o Type of contraction, familiarization, method of loading, technique, positioning etc — all influence assessment and therefore the accuracy & interpretation of the results.

Question 6

Types of Contractions

Answer 6

o Static/Isometric
o Dynamic/Isotonic

Question 7

o Dynamic/Isotonic contraction

Answer 7

– Generation of force to move and object
– Muscle is shortened during contraction (Concentric contraction)
– Muscle is lengthened during contraction (Eccentric contraction)

Question 8

o Static/Isometric

Answer 8

– Generation of force without movement

Question 9

(Concentric contraction)

Answer 9

Muscle is shortened during contraction

Question 10

(Eccentric contraction)

Answer 10

Muscle is lengthened during contraction

Question 11

familiarisation

Answer 11

o Some assessment tasks are uncommon to client
– Performance is improved through learning & practice (learning effect)

o Most clients will require a learning and familiarization period
– Technique and equipment

o Include a warm-up prior to assessment (light aerobic exercise and low intensity reps of the assessment task)
– Increase blood circulation to muscles
– Help refamiliarize the client with the assessment task.

Question 12

Methods of Loading for Assessment of Strength and Endurance

Answer 12

o Methods used to load the muscle during assessment
– Free weights
– Resistance exercise machines
– Individual’s body weight
o Discuss the pros & cons
– Client safety
– Isolate individual muscle groups
– Range of tests
– Equipment

Question 13

Proper Positioning & Correct Technique

Answer 13

o Essential for free weights, machines, and body weight
o Improper positioning or incorrect technique potentially allows other muscle groups to contribute to movement of load.
o Proper positioning and correct technique
– allows for accurate measurement of the muscle group being assessed (i.e. isolates the muscle group)
– Necessary for the safety of the client

Question 14

Standardised Procedures

Answer 14

o Reliability and accuracy of measurements are enhanced by following standardised procedures and performing tests and repeat tests consistently
– Proper positioning throughout test
– Correct technique throughout the test
– Familiarization period
– Use same equipment/method to load the muscle
– Speed of movement consistent
– Full range of motion (ROM)
o Interpreting results using normative data, need to use the same procedures including the same equipment as was used to develop the norms

Question 15

What are the major muscle groups

Answer 15

1. Deltoids
2. Latissimus dorsi, Trapezius, Rhomboids
3. Pectoralis
4. Rectus abdominis
5. Gluteus maximus
6. Vastus lateralis and rectus femoris
7. Biceps femoris
8. Soleus and Gastrocnemius

Question 15

strengths assessment

Answer 15

o No single measure of muscular strength for an individual
o Best case scenario: assess a range of different muscles/muscle groups, produce a composite score to assess overall strength
o Limited for individuals with above average strength in some muscle groups and below average in others

Question 16

Strength Assessments: Static

Answer 16

o Dynamometers
– Grip strength
– Maximal force is applied and read.
– Hand & forearm muscles
– Used a general test of strength

Question 17

Grip Strength

Answer 17

o Strengths: inexpensive, easy to perform, easy to interpret, widely used test of general strength, suitable for all clients, good reliability (if standardised procedures are followed).

o Limitations: Good measure of grip strength (good validity) but poor measure of general strength in some people (poor validity)

o Requirements: Grip dynamometer

o Factors affecting reliability and validity of the
o measurement will be discussed in the practical session

Question 18

Strength Assessments: Dynamic

Answer 18

1. Repetition Maximum (1 - RM)
   o Gold standard test for assessing dynamic strength
   o Maximum amount of weight a client can lift in one rep through full ROM in a controlled manner with good posture
   o Performed with any muscle group
   o Can be tested using free weights or machines
   – Bench press—norm for upper body
   – Leg press—norm for lower body

Question 19

1-RM Tests

Answer 19

o Strengths: gold standard, measure a range of muscle groups, use free weights or machines, excellent reliability, and validity (if standardised procedures are followed), interpret results against norms.
o Limitations: need to be familiar with technique, suitable for experienced clients only, client safety
o Requirements: Good technique, equipment, spotter for safety reasons
o Many factors can affect reliability and validity of the test
o Alternatives: 3 or 5-RM used to predict 1-RM value using an equation

Question 20

Endurance Assessments

Answer 20

o Fixed number of contractions in a defined period (e.g. 1 minute)
o Maximal number of contractions at set rate and resistance/load until exhaustion
o A static contraction held for time
o Tested using free weights, resistance machines or body weight

Question 21

Endurance Assessments: Dynamic
(Field Tests)

Answer 21

o Able to test large groups of people
o No equipment required
o Common tests include curl-ups and push-ups (modified push-up)
o Maximal repetitions performed with proper technique in e.g. 1 min or until exhaustion.
o Suitable for a range of clients
o Standard technique and procedures is crucial (for interpretation using normative values).
o Strengths and limitations

Question 22

Assessing Muscular Fitness in Older Adults and Clinical Groups

Answer 22

o There may be more appropriate assessments of muscular strength and endurance (MS & E) for these groups (covered in Alison’s 4th year class)
– Safer
– Assess aspects of muscular fitness that are important for common everyday activities