individual muscle fibers. At the level of muscle cells, depletion of energy stores may be important.Regular exercise improves muscular function and delays the onset of fatigue, thus increasing the amount and duration of work that can be performed. Exercise is important for optimal athletic performance, prevention of injury in athletes and non-athletes, and the maintenance of good general health.In this experiment, you will examine the effect of fatigue on muscle action by performing sustained and repetitive isometric contractions of muscles of the arm and hand using a Vernier Hand Dynamometer.Important: Do not attempt this experiment if you have arthritis, or other conditions of the hand,wrist, forearm, or elbow. Inform your instructor of any possible health problems that might be exacerbated if you participate in this exercise.Figure 1
17 - 8Human Physiology with VernierLabQuest 17OBJECTIVESIn this experiment, you willObtain graphical representation of the force exerted by your hand while gripping.Observe the change in hand strength during a continuous grip over time.Observe the change in hand strength during rapid, repetitive gripping.MATERIALSLabQuest LabQuest AppVernier Hand DynamometerPROCEDURESelect one person from your lab group to be the subject.Part I Muscle Strength with Continuous Grip 1.Connect the Hand Dynamomenter to LabQuest.2.On the Meter screen, tap Length. Change the data-collection length to100 seconds. Select OK.3.Zero the readings for the Hand Dynamometer.c.Hold the Hand Dynamometer along the sides, in an upright position(see Figure 2). Do not put any force on the pads of the HandDynamometer.d.When the readings stabilize, choose Zero from the Sensors menu. Thereadings for the sensor should be close to zero. 4.Have the subject sit with his/her back straight and feet flat on thefloor. The Hand Dynamometer should be held in the dominant hand.The elbow should be at a 90° angle, with the arm unsupported (seeFigure 3). 5.Have the subject close his/her eyes, or avert them from the screen.6.Instruct the subject to grip the sensor with full strength and start datacollection. The subject should exert maximum effort with each gripthroughout the duration of the experiment.7.At 90 s, the lab partner(s) should encourage the subject to grip evenharder. Data will be collected for 100 s. 8.Determine the maximum force exerted during different time intervals.d.Tap and drag across the data from 0 s to 10 s.e.Choose Statistics from the Analyze menu. f.Record the maximum force in Table 1, rounding to the nearest 0.1 N. g.Choose Statistics from the Analyze menu to turn off statistics.9.Repeat Step 8 for the remaining 10 second intervals: 20−30 s, 40−50 s, 60−70 s, and 80−90 Figure 3Figure 2
Human Physiology with Vernier17 - 9Grip Strength and Muscle Fatigues.