LABORATORY REPORT 2. Measurement of Isotonic Strength & Power, Isometric Strength

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Eunice Osborne
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1 LABORATORY REPORT 2 Measurement of Isotonic Strength & Power, Isometric Strength NAME: Raquel Trejo SECTION I: INTRODUCTION (5 points) The purpose of Lab 2 was to demonstrate different methods of reaching a 1 RM and its validity. Dynamic contractions were performed in the measurement of 1-RM and static contractions was performed for grip strength. A dynamic contraction is when a muscle that is generating tension is either shortening or lengthening. Static contraction is when a muscle is generating tension, but the muscle is neither shortening nor lengthening. This is present when the force was measured during the grip strength exercise. Other factors considered during this lab was isotonic and isometric movements. Isotonic is when the muscle has a set resistance throughout the movement. Isometric is comparable to static contractions which there is no change in the length of the muscle while providing tension. The primary focus during this laboratory study was to determine the 1-RM by two different methods and to compare the results. The static contraction was studied to determine if the subject had comparable norms for grip strength. SECTION II: REVIEW OF LITERATURE (10 points) Kocjan et. al. discussed in the article the importance of trunk strength when the hips were in flexion and extension positions in regard to the position of the hip joint. Depending on the hip joint then would produce less or greater of a static contraction. This was similar to the grip strength exercise when the subject was in a seated and standing position. Another point Kocjan et. al. discussed was the increased strength depending on the plane the movement was occurring in. The highest strength occurred in the sagittal plane while the frontal plane was the least strength. This could also be used for the bench press calculations in knowing the movements were being performed were actually helping aid in the most beneficial movement.

2 SECTION III: METHODS (5 points) The subject for the lab was a 21 year old, overall healthy female. To calculate the 1-RM, the bench press machine was used for the upper extremity. The length of the subject s arm was measured while she performed her first bench press while in extension. She began her warm-up repetitions at 30 kg and did 10 repetitions. She then increased the weight to 40 kg and performed another set of 5 repetitions. After resting for a minute, the test began. She first began with kg of weight and performed one repetition. The weight was increased and another repetition was performed. This was done for a total of three repetitions once the subject could no longer perform the bench press. The weight that was last performed was compared to the Table 4.3 to calculate the 1-RM. Next, the grip strength was measured using a dynamometer. Grip strength was measured in both the dominant and non-dominant hand, sitting and standing. The subject was first tested while standing facing forward with her elbow in full extension and fingers gripping creating a right angle. Her radio-ulnar joint was in the mid-position. Three trials were performed each with the dominant and non-dominant hand with 1 minute rest period between each trial. Next, the subject sat with feet flat on the floor with the same arm positioning as standing. Three trials were performed each with the dominant and non-dominant had with 1 minute rest period between each trial. With each trial the subject was told to squeeze as hard as she could with two squeezes and then relax. To test the lower extremity, the same procedure was followed as the upper extremity. The subject performed a warm up and measured the length of her leg in full extension from the hip to her heal. After completing warm-ups the subject bench pressed one repetition with one minute of rest between each until she could no longer complete the exercise. The mean of both the lower and upper extremity weight was calculated and the maximal weight was converted to Newtons. The second method for calculating 1-RM was to determine how much the subject could comfortably, but forcefully complete 3-12 repetitions of the maximal weight and then use an equation to convert it to 1-RM. %1RM= 100 (#reps * 2.5) then 1RM =weight lifted/ (%1RM/100) This calculation was then compared to the actual 1 RM that was performed in the previous trials. SECTION IV: RESULTS (5 points) The results comparing the indirect estimation of bench press (upper extremity) using the Table 4.3 was approximately 133 kg while using the equations was 139 kg. Power was calculated of the bench press and it was Watts. The lower extremity 1-RM using the equation was 314 kg. Power was also calculated for the lower extremity and was 752 Watts.

3 The best scores for the grip strength for the seated dominant hand was 27 kg/force. The first trial was 27 kg/force, trial 2 was 26 kg/force and trial 3 was 24 kg/force. The dominant standing grip strength for trial 1 was 24 kg/force, trial 2 was 30 kg/force and trial 3 was 25 kg/force with the 30 kg/force being the best score. The seated nondominant hand trial 1 was 26 kg/force, 24 kg/force, 26 kg/force with the best score of 26 kg/force. The standing non-dominant hand grip strength trial 1 was 28 kg/force, trial 2 was 27 kg/force and 20 kg/force. SECTION V: DISCUSSION/ANALYSIS (10 points) Using Table 5.1 to compare the average right, maximum hand grip strength the subject was below average only with the non-dominant seated position. All other trials the subject was in the average of /- 5.5 kg. It would be expected that the overall grip strength would be higher while standing because more muscle could be recruited as synergist muscles to aid in grip strength. The non-dominant hand was surprisingly similar to the dominant hand in both seated and standing positions. There was a slight difference in the two different methods of calculating the 1-RM of the subject only by 6 kg. The lower extremity calculation seemed to be extremely high for the subject. The maximal 1-RM the subject was able to perform was 106 kg, however the calculation predicted the subject to be able to perform 314 kg. This is 208 kg more than the subject was able to perform. Either the calculation is incorrect or inaccurate. The amount of power does need to be taken into consideration along with any fatigue that may have occurred during the bout of exercise. The upper extremity also seemed inaccurate with the calculation given 87 kg more than the 1-RM that was performed. The subject is a collegiate athlete that has regular weight training sessions. The subject is used to the equipment and aware of what her body is capable of lifting. SECTION VI: CONCLUSIONS/IMPLICATIONS (5 points) In conclusion, the direct measurement of both upper and lower extremity is more accurate than the indirect estimation. The subject was able to demonstrate this both with the 1-RM along with the 3-RM. The amount of power calculated helped to explain the probability of the indirect estimation not being an accurate and reliable way of calculating maximal strength.

4 REFERENCE: Kocjan A, Sarabon N. Assessment of isometric trunk strength- The relevance of body position and relationship between planes of movement. Journal Of Sports Science & Medicine [serial online]. June 2014; 13(2): Available from: Academic Search Premier, Ipswich, MA. Accessed September 22, 2014.

5 DATA COLLECTION: ISOTONIC STRENGTH FORM 2.1 STUDENT NAME: Raquel Trejo DATE: 9/9/2014 Subject Name: Age: 21 M/F: F Direct Measurement of Bench Press 1-RM: Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Mean kg. 46 kg. 52 kg. kg. kg kg. Calculation of Bench Press Power (Watts): P= (N * m)/sec P= (168.95N * 0.555m)/1.12 sec= Watts Indirect Estimation of Bench Press 1-RM: From Table kg From Equations: 139 kg

6 Direct Measurement of Leg Press 1-RM: Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Mean 79 kg. 86 kg. 92 kg. 99 kg. 106 kg kg. Calculation of Leg Press Power (Watts): P= (N*m)/sec P= (906N * 0.93m)/1.12 sec = 752 Watts Indirect Estimation of Leg Press 1-RM: From Equations: 314 kg

7 DATA COLLECTION: ISOMETRIC STRENGTH FORM 2.2 STUDENT NAME: Raquel Trejo DATE: 9/9/2014 Subject Name: Age: 21 M/F: F Grip Strength Measurement Dominant hand: Trial #1 Trial #2 Trial #3 Best Score Seated Standing Non-dominant hand: Trial #1 Trial #2 Trial #3 Best Score Seated Standing

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