Stretching leg muscles before exercise leads to an increase in blood flow. This leads to a higher requirement of oxygen and this causes a higher than normal heart rate before the actual exercise. Since the blood is already flowing at a quicker rate the heart rate should increase at a slower rate. There will be a decrease in demand for blood and oxygen from the muscles as there are already in an “excited” state.
Sources:
http://circ.ahajournals.org/content/93/5/1043.full
In this experiment the form of exercise will running on a treadmill.
Variables:
Independent variable: Stretching hamstring, calf and thigh muscles before the exercise.
Dependent variable: Heart rate variability. The rate of change in heart rate (beats per minute)
Controlled variables: The age (17 year old), height (175 ± 3 cm) and weight (65± 5 kg) and gender of the participants in order to keep it a fair test. All these 4 factors affect the heart rate of a person. The exercises and stretch conducted by each participant needs to be the same and need to be done in the same environmental conditions (20 degrees Celsius, audio and visual interference, humidity and atmospheric pressure). A small demonstration of the 3 stretches (hamstring stretch; calf stretch and the thigh stretch) should be given before the experiment in order to make sure each participant does the same stretch. Doing the experiment in the same room for each participant can control the environmental conditions. The duration of the stretch (2 minute each) and exercise (5 minutes) needs to be controlled too. The resting time between the exercise before stretching and after stretching needs to be the same too (30 minutes). The speed of the treadmill should be constant at 8 kilometers per hour and there should be no incline.
Materials:
- A treadmill
- A stop watch
- Participants (ten 17 years old boys)
- One wall (to lean against for stretching)
- A heart rate monitor
Procedure:
- Measure each participants resting heat rate. Using the Heart Rate Monitor.
- Record this date on the table.
- After the heart rate is measured, set the speed of the treadmill to 8.
- After the treadmill’s speed is set, ask the participant to start running on the treadmill.
- Use the stopwatch to determine the time. The exercise should last 5 minutes.
- After the exercise, repeat the step 1 to determine the heart rate after exercise.
- Record this data.
- Make the participant then rest for 30 minutes and prevent them from doing any physically demand task. This is the resting period and this should provide enough time for the heart rate to return back to normal.
- After the 30 minutes are over, as the participant to do the thigh stretch as shown in the picture below and hold this position for 2 minutes. Ensure that they shift from leg to leg every 15 seconds.
10. After the two minutes of thigh stretch the participant next need to do the two minutes calf stretch. This requires the participant to push on the wall with their hands while pushing down on their back leg as shown in the picture below. This should be done for two minutes too and the legs should be switched every 15 seconds.
11. After the calf stretch, the participant now needs to do a two minutes hamstring stretch. This is done by putting one foot in front of the other and then leaning on the front one as demonstrated on the picture below. Switch between each leg every 15 seconds.
12. The participant should have done 6 minutes of stretching in total. After this, repeat step 1 and 2 to determine and record heart rate.
13. Then repeat step 2-6.
14. Repeat step 1-13 for the next 9 participants and records each individual’s data.
Data Collection:
Table 1: Data without Stretching.
Table 2: Data with Stretching.
by
bub2 (student)
