Grip Strength Experiment 9 Grip strength is the force applied by your hand. It is an important part of daily life from eating to playing baseball. There are three main types of grip strength depending on the way you use your hands. In the crush grip (the most common), your hand wraps around an object so that your palm and all your fingers rest against the object. This grip is used for breaking objects with pressure. In the pinch grip, you grasp an object with only your thumb and one finger. Pointer or middle fingers usually have significantly more strength than ring and pinkie fingers. In the supportive grip, you are measuring your ability to carry an object for a long period of time, such as a sack of groceries. This grip is normally used as an indicator of how much your hand fatigues or tires over time. In this activity, you will use a Gas Pressure Sensor and a 2-liter bottle to compare the grip strength of your right and left hands. Pressure can be used as a relative strength indicator, since pressure is measured in kilopascals (thousands of Newtons per square meter) and everyone in your class will be squeezing bottles with the same area. After you have analyzed your data, you will compare your grip strength with that of your classmates. OBJECTIVES Figure 1: Measuring grip strength with the Gas Pressure Sensor In this experiment, you will Use a Pressure Sensor and NXT to measure your grip strength. See which of your hands has the greater grip strength. Learn what happens to your grip strength as time goes by. Compare your grip strength with your classmates. Evaluation copy MATERIALS computer LEGO NXT Intelligent Brick MINDSTORMS Edu NXT 2 software Vernier NXT Sensor Adapter NXT cable Vernier Gas Pressure Sensor plastic bottle one-hole stopper assembly heavy-wall plastic tubing STEM 2 with Vernier and LEGO MINDSTORMS NXT 9-1
Experiment 9 PROCEDURE 1. Insert the one-hole stopper assembly on the end of the Gas Pressure Sensor into a clean, empty plastic bottle as shown in Figure 1. Make sure the stopper is firmly inserted so there are no leaks. 2. Connect the NXT for data collection. a. Connect the Gas Pressure Sensor to the Vernier NXT Sensor Adapter. b. Connect the Adapter to Port 1 on the NXT using a LEGO NXT cable. c. Make sure the NXT is connected to the computer (USB or Bluetooth) and turned on. 3. Launch NXT 2 Data Logging. 4. Click the Go button next to Start New Experiment. 5. Set up the experiment. a. In the Experiment Configuration window, select Vernier Pressure by clicking on the pulldown list to the left of Port 1. (Notice the indicator box changes from gray to green.) b. Adjust the Duration to 60 seconds. c. Adjust the Rate to 1 sample per second. d. Click the OK button. 6. Click the Download and Run button to begin data collection. When the NXT beeps, grip the bottle as hard as you can with your left hand. Continue squeezing for 60 seconds. Do not look at the computer screen while you are squeezing. 7. When data collection ends, record your data. a. Click the Analysis Tools button,, and select Section Analysis. b. Drag the left and right edges of the gray strip until it is covering the linearly decreasing part of the graph. Do not include the initial pressure increase when the bottle is first squeezed. c. Record your mean (average) grip strength for the 60 s period in Table 1. d. Adjust the right edge of the gray strip until it is covering the initial 10 s of linear decrease. Do not move the left edge. e. Record your mean grip strength for the initial 10 s period in Table 1. f. Adjust the left and right edges of the gray strip until it is covering the final 10 s period. g. Record your mean grip strength for the final 10 s period in Table 1. 8. Repeat Steps 6 7 using your right hand. 9-2 STEM 2 with Vernier and LEGO MINDSTORMS NXT
Grip Strength DATA Table 1 Your Results Left hand Right hand 0 60 sec average grip strength (kpa) Initial 10 sec average grip strength (kpa) Final 10 sec average grip strength (kpa) Difference between final and initial averages Table 2 Group and Class Results Name Strong hand average for 0 60 s (kpa) Group average Class average PROCESSING THE DATA 1. Subtract to find the difference between your 0 10 s average and your 50 60 s average for each hand. Record your results in Table 1. 2. Record the 0 60 s average grip strength in Table 2 for the other students in your work group. Only record the grip strength of the stronger hand. 3. Calculate and record your group s average grip strength. 4. Calculate and record the average grip strength for the entire class. 5. Which of your hands is stronger? Explain. 6. Did your grip strength increase or decrease during the 60 s period? Why did it change? 7. How does your grip strength compare with the class average? STEM 2 with Vernier and LEGO MINDSTORMS NXT 9-3
Experiment 9 8. What did you learn about your strength in this experiment? Were you surprised? EXTENSION 1. See if you can increase your gripping strength with practice. Perform daily handstrengthening exercises to increase your grip strength (such as squeezing a rubber ball). Measure your grip strength after two weeks and after four weeks. Compare the results with your original data. 2. Investigate whether cheering and encouragement have an effect on grip strength. Repeat the experiment making sure the subject does not look at the data as it is being recorded. After 50 seconds, have one or more students verbally encourage the subject to grip harder. The louder and more enthusiastic you cheer, the better. Did you notice a measureable difference in your graph? Explain. 3. Repeat this activity, but allow the subject to look at the computer screen while the data is graphing. Is there a noticeable difference in grip strength between looking and not looking at the data during graphing? Explain. 4. Compare the pinch strength of the four fingers of your hand (or both hands). The introduction of this experiment says the middle finger is the strongest. Is this true? 9-4 STEM 2 with Vernier and LEGO MINDSTORMS NXT
Vernier Lab Safety Instructions Disclaimer THIS IS AN EVALUATION COPY OF THE VERNIER STUDENT LAB. This copy does not include: Safety information Essential instructor background information Directions for preparing solutions Important tips for successfully doing these labs The complete STEM 2 with Vernier and LEGO MINDSTORMS NXT lab manual includes 12 lab activities and eight projects as well as essential teacher information. The full lab book is available for purchase at: http://www.vernier.com/cmat/stem2.html Vernier Software & Technology 13979 S.W. Millikan Way Beaverton, OR 97005-2886 Toll Free (888) 837-6437 (503) 277-2299 FAX (503) 277-2440 info@vernier.com www.vernier.com