LAB 2​​

Demonstration of Cycle Ergometer and Step Submaximal Graded Exercise Tests

Purpose

This laboratory experience is designed to illustrate the pretesting, testing, and posttesting procedures for conducting a submaximal graded exercise test (GXT) on the cycle ergometer and step and to develop your skill in administering these tests.

Equipment

· Stationary cycle ergometer

· Step with risers

· HR monitor

· Sphygmomanometer

· Metronome

Student Assignments

1. Select one apparently healthy student to serve as the client.

2. Select one or two students to prep the client for the test.

3. Assign one student to monitor and collect HR data from HR monitor.

4. Select one student to measure palpated HRs.

5. Select one student to measure BPs.

6. Select one student to set and monitor work rates on cycle ergometer.

7. Select one student to monitor client throughout test and to obtain client’s RPE.

Testing Procedures

1. Select an appropriate cycle ergometer protocol for the client.

2. Prepare the client for the test, explain purpose and nature of the GXT, measure height and body weight, position electrodes, and calculate target HR for test termination if required by the GXT protocol.

3. Collect resting data. Measure resting HR using palpation and HR monitor. Measure resting BP using auscultatory method.

4. Collect exercise data. Measure exercise HR every minute using palpation and HR monitor. Measure exercise BP during last 2 min of each stage of test. Ask client for RPE during last minute of each stage of test. Closely monitor client throughout test, checking for signs and symptoms that indicate the test should be terminated. Make certain that client achieves a steady-state HR during the last 2 min of each stage (HR values within ±5 to 6 bpm) before increasing the work rate.

5. Continue GXT until test protocol is completed or target exercise HR is achieved, or HR, BP data indicate test should be stopped, or client voluntarily terminates the test.

6. Collect recovery data for 3 to 5 min. Measure recovery HR every minute using palpation and HR monitor. Measure recovery BP every 2 to 3 min.

Data Analysis

1. Use the HR and work rate data from the last two exercise stages to estimate the client’s VO2max using the multistage method. Hint: Use the ACSM cycle ergometry equation (see table 4.3) to calculate the metabolic cost for the last two exercise stages. Note: Use ACSM equation only if client obtained steady state (i.e., HRs during last 2 min of each stage are within ±5 to 6 bpm) for the last two stages of the GXT.

2. Graph the HR versus energy cost (ml · kg-1 · min-1) data for the last two stages. Estimate the client’s VO2max using the graphing method.

3. Determine the client’s cardiorespiratory fitness level by classifying the estimated VO2max (see table 4.1).

4. Graph the client’s HR response during each minute of exercise and recovery. Plot HR on the y-axis and time on the x-axis.

5. Extra credit: Correlate the client’s exercise HRs obtained from palpation and the HR monitor using the Pearson product-moment correlation technique (rx,y).

Data Collection Form for Cycle Ergometer and Step Submaximal Graded Exercise Test

Client’s Demographics

Resting Data

HR ____86__ bpm

BP ____125/80__ mmHg

GXT Test 1 Data: Astrand-Rhyming Cycle Ergometer Test

Protocol __________________

Target HR for test termination (if needed) ________ bpm

Recovery Data HR Sys Dys

Reasons for stopping the test:

GXT Test 2 Data: Harvard Step Test

Protocol __________________

Target HR for test termination (if needed) ___188_____ bpm

Recovery Data

Reasons for stopping the test:

Converting predicted VO2 max values from absolute (L/min) to relative (ml/kg/min).

mL/min = L/min *1000

mL/kg/min = mL/ body weight in kg

Ex. An 80 kg man achieved a peak VO2 of 4.7 L/min

4700 mL/min = 4.7 L/min *1000

58.75 mL/kg/min = 4700 mL/min/ 80kg

Lab report: Due October 15

This lab is a comparison between the submaximal step test and submaximal bike test. You will be comparing your data and evaluating results from each test.

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Dangerously Thin: A Case Study on the Genetic Code

At 65 years old, Henry Blake was in excellent health and enjoying his first year of retirement. Upon returning from his dream trip to the Great Barrier Reef in Australia, he noticed that his left leg was swollen just inferior to the knee. He already had scheduled an appointment for a complete physical, so he knew that in a few days he would be able to have his physician look at his leg.

Dr. Strickland had been the Blake family doctor for more than 40 years. Knowing that Henry had planned to do some traveling, Dr. Strickland opened with a question that Henry initially found to be a bit out of the ordinary.

“Any chance this swelling showed up after a long flight?”

“As a matter of fact it did,” Henry replied.

“My gut tells me that you may have a clot in that leg, but we’ll have to have a look at it before we’ll know for sure.”

Dr. Strickland knew that Henry’s family had a history of clotting disorders, and he had recently treated Henry’s brother for a deep vein thrombosis (DVT), a disorder that gets its name from the blood clots that form in a vein deep within the leg. A DVT was confirmed by the Doppler ultrasonography results (a test that uses sound to create images of blood flow). Dr. Strickland placed Henry on a “blood thinning” drug called warfarin, which works by preventing clots from forming.

Henry returned to his retirement plans but quickly found himself back in Dr. Strickland’s office after suffering from frequent nose bleeds. A laboratory test called an INR (International Normalized Ratio) was performed. This test measures the time it takes for blood to clot and compares it to an average. The test revealed that the time it took for Henry’s blood to clot was well above what would be expected for the dose of warfarin that he had been placed on. Dr. Strickland immediately took Henry off of his warfarin treatments and asked that he come in every three days for blood tests. Dr. Strickland became concerned when Henry’s abnormal INR results continued long after he had stopped taking warfarin.

Through genetic testing, Henry was found to carry a mutation in a gene for an enzyme called CYP2C9. While the strange name of the gene does not really fully appear to capture the importance of its function, it has a role in breaking down more than 15% of the drugs currently in use, and as many as 35% of people carry a slower acting form of this enzyme. The portion of Henry’s DNA that codes for the CYP2C9 enzyme contains more than 1,400 nucleotides. Henry carries two copies of the CYP2C9 gene, and the tests showed that both of them contain a mutation. On one of these genes, the 1075th nucleotide has been changed from an adenine (A) to a cytosine (C). This mutation converts an ATT triplet code in the coding strand of the DNA molecule to CTT. In Henry’s other CYP2C9 gene, the 430th nucleotide has been changed from a cytosine (C) to a thymine (T). The DNA triplet code CGT in the coding strand becomes TGT as a result of this mutation. Henry was considered a poor metabolizer (PM) because both of his CYP2C9 genes contained a mutation, and therefore he was not making any fully functional enzyme. People who carry two normal copies of the gene are referred to as extensive metabolizers (EM) for their ability to quickly break down drug molecules.

Short Answer Questions

1. Why would someone with this type of mutation be at a much higher risk for overdosing on a prescribed drug?

2. The underlying problem in this case resides in Henry’s “genes.” From what you know about the function of a gene, explain how this problem led to a malfunction in one of Henry’s proteins (the CYP2C9 enzyme).

3. The DNA changes that are described in Henry’s story are changes to the coding strands of the CYP2C9 genes. What is the function of the coding strand and how does it differ from the function of the template strand of Henry’s CYP2C9 gene?

4. Consider the following DNA sequence found on a different portion the coding strand of Henry’s CYP2C9 gene: TTACCGAGA

a. What would be the sequence of the template strand on this portion of the gene?

b. How many triplet codes does this DNA sequence contain?

c. What would be the sequence of the mRNA after this sequence is transcribed?

d. How many amino acids does this portion of Henry’s coding stand actually code for?

5. In the first mutation of the CYP2C9 gene described in Henry’s story, the 1075th nucleotide had changed from an adenine (A) to a cytosine (C). This mutation converts an ATT triplet code in the coding strand of the DNA molecule to CTT. Beginning with this triplet code on the DNA, describe the effect that this change would have on the following:

a. The nucleotide sequence on the template strand of the gene.

b. The mRNA codon that results after this triplet code is transcribed.

c. The anticodon on the tRNA molecule that is complementary to the mRNA codon described above.

d. The amino acid that would be carried by the tRNA molecule described above.

6. In Henry’s other CYP2C9 gene, the 430th nucleotide had changed from a cytosine (C) to a thymine (T). This mutation converts a CGT triplet code in the coding strand of the DNA molecule to TGT. Beginning with this triplet code on the DNA, describe the effect that this change would have on the following:

a. The nucleotide sequence on the template strand of the gene.

b. The mRNA codon that results after this triplet code is transcribed.

c. The anticodon on the tRNA molecule that is complementary to the mRNA codon described above.

d. The amino acid that would be carried by the tRNA molecule described above.

7. From what you understand about enzymes, explain why a change in an amino acid would cause Harry’s enzyme to lose its function.

8. In both of Henry’s mutations, it is the first nucleotide in the DNA triplet code that has been changed.

a. Using the genetic code chart below, create a list of single nucleotide changes in the two affected triplet codes described for Henry’s genes that could occur WITHOUT resulting in a change in the amino acid in the enzyme.

NOTE: The code chart below contains mRNA codons and the amino acids associated with those codons. Your list should contain DNA triplet codes.

b. How many triplet code changes did you find that could occur WITHOUT resulting in an amino acid change in the enzyme?

c. Which position (first, second, or third) did the changes occur within the DNA triplet codes you listed above?

d. What would you conclude from the pattern that emerged?

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