DPT-306.2-PT Essentials – Dynamic Testing: Muscular Strength & Endurance

You must first complete DPT-306.1-PT Essentials – Dynamic Testing: Aerobic Capacity before viewing this Lesson

One of the key components of physical fitness is muscular strength. It is defined as ‘the force a muscle or group of muscles can apply against a given resistance’ (Graves, Pollock and Bryant, 1998). Not only is it a key determinant of the performance of many sports, but it is also crucially important for activities of daily living (ADLs). It can be expressed in a number of different ways: 

Maximal strength – the maximal amount of force a muscle or group of muscles can generate (Fleck and Kraemer, 1997)

Absolute strength – the raw strength score a person achieves (Cramer and Coburn, 2004)

Speed strength – the ability to overcome an external resistance at a high rate of muscle contraction in a given unit of time (Hartmann and Tunnemann, 2000)

Relative strength/endurance – the most force your muscles can produce in relation to your body weight (Telle, 1994).

Endurance strength – the ability of a muscle or group of muscles to sustain repeated contractions of a given force for an extended period of time (Graves et al, 1998).

Elastic/reactive strength – the ability to rapidly change from an eccentric to a concentric muscle contraction.

There are a variety of tests to measure muscular strength and muscular endurance. The choice of test selection is very dependent on the goals of the individual, their current training status, injuries and a number of other factors. With individuals relatively new to resistance training there are a number of safety factors, which would indicate the preference of muscular endurance tests to strength tests.

The Importance of Safety

For beginners without a background in exercise, it may not be advisable to test a client to exhaustion at any number of reps (Howley and Franks, 1995).  There are several important reasons why:

  • an all-out test is hard work, painful and can put some clients off further resistance training.
  • an all-out test may result in delayed onset muscle soreness (DOMS). This may also put some clients off further training.
  • if the client focuses on going to maximum, good form will almost certainly be lost. In the early days of resistance training, good technique is much more important than maximum exertion.
  • a beginner is at particular risk of injury if exercising to maximum. This particularly applies to ligaments and tendons, which take longer to gain strength than muscles. This comes through training. Using heavy free weights before this co-ordination is developed, is potentially dangerous.

Tests

Maximum muscle strength: (low speed strength)

  • hand grip dynamometer
  • 1RM protocol

Hand grip dynamometer:

  • have the person being tested dry their hands and ask if the client has any weakness in the wrist and forearm
  • adjust the gripping mechanism so that the second joint of the hand fits snugly under the handle.  The dynamometer should be gripped between the fingers and the base of the thumb
  • the hand being tested should be held out in front of the body, free from contact with the body
  • the client should adopt a stable position, with knees soft and elbow slightly flexed.
  • the client should be given two to four trials on each hand with the higher reading from each hand recorded
  • the importance of breathing should be emphasised.

One of the major drawbacks in using a static test to assess strength is that strength is only measured in one or a small select group of muscles.  While researchers have tried to develop tests using muscles that are representative of total body strength, they have not fully done so.

One repetition maximum (1RM) protocol:

Dynamic strength is usually measured as the 1RM, which is the maximum weight that can be lifted for one complete repetition of that movement with perfect technique (Heyward, 2002).

After familiarising themselves with the equipment, they are given several chances to achieve a maximal repetition with the resistance being increased incrementally with each trial. A maximum movement is hopefully attained within five trials so that fatigue does not become a confounding factor (Harman, Garhammer and Pandorf, 2000).  

1RM testing protocol: (adapted from Earle, 1999)

  • instruct the athlete to warm-up with a light resistance that easily allows 5-10 reps
  • provide a 1-minute rest period
  • estimate a warm up load that will allow the client to complete 3-5 reps by adding:
  • 4-9 kg or 5-10% for upper body exercise
  • 14-18 kg or 10-20% for lower body exercise
  • provide a 2-minute rest period
  • estimate a conservative, near maximum load that will allow the client to complete 2-3 reps by adding the same increments as before
  • provide a 2-4 minute rest period
  • make a load increase using the same increments as before
  • instruct the client to attempt a 1RM
  • if successful allow a 2-4 minute rest period, then go estimate a new load 
  • if unsuccessful allow a 2-4 minute rest period, then decrease the load by subtracting: 
  • 4-9 kg or 5-10% for upper body exercise
  • 14-18 kg or 10-20% for lower-body exercise

Continue increasing or decreasing the load until the client achieves a 1RM with good technique.

This will give the client’s absolute strength scores. In order to calculate the client’s relative strength score, simply divide the absolute score by their bodyweight.

Strength prescriptions are then developed from the 1RM (one repetition maximum) starting with approximately 50% of that value. 

  • at least one upper and lower body test should be performed as a minimum, using compound movements that require the interaction of a large number of muscles, such as a squat or deadlift (Baechle et al, 2000).  

Estimated strength test: (taken from Sandler, 2005)

The estimated strength test is an alternative to the 1RM test; therefore, suitable for clients who should not be taken to maximum. These tests rely on a formula to predict maximum strength. Select one exercise for the upper body and one for the lower body. As with the 1RM test a suitable warm-up using a light weight for 5 to 10 reps should be performed. Follow the warm-up with a two minute rest then select a weight that failure is reached anywhere between 2 and 10 reps. The following formulae can be used to predict maximum strength:

upper body rep max predictor:
weight used for reps x                   
1
_______________________
(1 – [reps made x .025])                                                                

lower body rep max predictor:

weight used for reps x                   
1
_______________________
(1 – [reps made x .035])

Local muscular endurance

The following assessments check the slow twitch fibres of ones muscle group.

  • press up
  • abdominal curl
  • sub-maximal bench press
  • back extensor
  • lateral musculature
  • battery test

Press up:     

  • client assumes the normal press-up position, with the body rigid and straight, and arms shoulder width apart
  • the client must lower himself or herself to 90 degrees of elbow flexion
  • the test is the total number of completed press-ups to exhaustion
  • an alternative press-up version where the client raises from a position where the knees are in contact with the ground is available for those who cannot complete the above version

Press Up Norms by age:

Percentile20-2920-2930-3930-3940-4940-4950-5950-5960-6960-69
SexMFMFMFMFMF
9041323231252824232425
8034262724212217171615
7030222421191814131112
6027202117161411101010
5024161914131210996
402114161212109574
30181114101077362
2016911784514
10115845242

90 = well above average, 70 = above average, 50 = average, 30 = below average, 10 = well below average. 

 (Canada Fitness Survey, 1986)

Abdominal curl test:

The curl up, for abdominal muscular endurance, would seem preferable to the sit up test because of the decreased activation of the hip flexors (Kraemer and Fry, 1995).

  • ensure a matted area is available to cushion the lumbar spine
  • client lies on back, knees bent to 90 degrees with arms straight and palms down
  • the test is scored on the number of times the client can raise the shoulder blades off the mat (trunk at 30° of spinal flexion), so that the fingers touch a line equal to three inches away from the resting position

Curl test norms by age:

Percentile20-2920-2930-3930-3940-4940-4950-5950-5960-6960-69
SexMFMFMFMFMF
9075707555755074485350
8056456943754260303330
7041374634673345232624
6031323628512835161919
502727312139252791613
4024212615312023299
3020171912261419063
20131213021513000
1045001300000

90 = well above average, 70 = above average, 50 = average, 30 = below average, 10 = well below average. 

(Canada Fitness Survey, 1986)

Submaximal bench press:

Work out an appropriate weight using the following guidelines (Heyward, 2002):

  • males        – 66% bodyweight      (multiply weight by 0.66)
  • females     – 50% bodyweight      (multiply weight by 0.50)

If females’ training is largely resistance led it may be more beneficial to use 66% bodyweight.  

Note: it is inevitably the case that the higher the lean body mass percentage for any given client the greater the likelihood of performing well.

  • set the metronome at 60 bpm  
  • prepare the client with a light warm-up
  • position the client on the bench with knees on the bench and flexed
  • spotter should hand the barbell to the client, in the down position
  • after each extension, the barbell is returned to the down position and the client must keep in rhythm with the metronome. Each click represents a movement up or down
  • the test is scored on the number of successful repetitions and terminated when the client cannot reach full extension or breaks the cadence and cannot keep up with the rhythm
  • ensure the client breathes properly throughout the test

Back extensors test: (taken from McGill, 2002)

  • the client adopts the position tested by Biering-Sorensen (1984)
  • the client lies with the upper body extended over the table, hips, knees and pelvis secured
  • the arms are across the chest with the hands resting on the opposite shoulders
  • failure occurs when the client cannot hold a fixed horizontal position

Lateral musculature test: (taken from McGill, 2002)

  • the client adopts a full side bridge position
  • the client rests on one elbow and on the feet, with the top foot placed in front for support
  • the hips are lifted off the ground to create a straight line throughout the length of the body
  • the top hand is placed on the opposite shoulder
  • the client holds this static position for as long as good technique can be maintained
  • failure occurs when the straight body position cannot be maintained and the hips drop to the floor

Dynamic muscular endurance test battery:

The table below is adapted from Heyward (2002) and is an example of a battery of exercises, with which to assess muscular endurance. It is a useful aid in designing an exercise programme as we are able to get an indicator of both the ability to perform and the effort required. This provides better information to determine the weight required for the target repetition range. It may be useful to adapt the selection of exercises in this test to meet your client’s needs and goals.

Dynamic Muscular Endurance Test Battery
ExerciseMen % body weightWomen % body weightRepetitions (max = 15)RPE (1-10)
Bench Press 0.66 (66%)0.50 (50%)  
Lat pull down0.66 (66%)0.50 (50%)  
Leg extension0.50 (50%)0.50 (50%)  
Leg curl0.50 (50%)0.50 (50%)  
Arm curl0.33 (33%)0.25 (25%)  
Triceps extension0.33 (33%)0.25 (25%)  
Bent knee sit up   
Total reps (max = 105)
Total repsFitness category
91-105Excellent
77-90Very good
63-76Good
49-62Fair
35-48Poor
<35Very poor
References

Baechle, T. R., Earle, R. W. and Wathen, D. (2000). Resistance training. In Essentials of strength training and conditioning (Baechle, T. R. and Earle, R. W. eds.). pp. 395-425, Human Kinetics.

Biering-Sorensen, F. (1984). Physical measurements as risk indicators for low-back trouble over a one-year period. Spine, 9, 106-119.

Canada Fitness Survey (1986). Canadian Standardized Test of Fitness

Operations Manual. 3rd Edition, Fitness and Amateur Sport Canada.

Cramer, J. T. and Coburn, J. W. (2004). Fitness Testing Protocols and Norms. In Essentials of personal training(Baechle, T. R. and Earle, R. W. eds.). pp. 217-264, Human Kinetics.

Earle, R. W. (1999). Weight training exercise prescription. In Essentials of personal training symposium workbook. NSCA Certification Commission.

Fleck, S. J. and Kraemer, W. J. (1997). Designing Resistance Training Programmes. 2nd Edition, Human Kinetics.

Graves, J. E., Pollock, M. L. and Bryant, C. X. (1998). Assessment of muscular strength and endurance. In ACSM’s Resource Manual for Guidelines for Testing and Prescription (J. L. Roitman ed.). pp. 363-367, 3rd Edition, Williams and Wilkins.

Harman, E., Garhammer, J. and Pandorf, C. (2000). Administration, scoring and interpretation of selected tests. InEssentials of strength training and conditioning (Baechle, T. R. and Earle, R. W. eds.). pp. 287-317, Human Kinetics.

Hartmann, J., Tunnemann, H. (2000). Fitness and Strength Training for All Sports, Theory, Methods, Programs. Sport Books Publisher.

Heyward, V. H. (2002). Advanced Fitness Assessment and Exercise Prescription. Human Kinetics.

Howley, E. T. and Franks, D. B. (1995). Health and Fitness Instructors Handbook

Human Kinetics.

Kraemer, W. J. and Fry, A. C. (1995). Strength testing:development and evaluation of methodology. In Fitness and Sports Medicine: A health related approach (Maud, P. and Nieman, D. C. eds.). 3rd Edition, Bull Publishing.

Mayo, J. J. and Kravitz, L. (2003). Methods of Muscular Fitness Assessment. http://www.unm.edu/~kravitz/Article%20folder/musassess.html

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