FSE 02 The Impact of Different Insulation Levels on Heart Rate During Exercise

This experiment investigates how wearing different numbers of cotton hoodies during a 30-burpee workout affects insulation, heart rate response, and recovery time to heart rate homeostasis.

Background Research 

Keeping the body's core temperature within a tight range is vital for survival, relying on intricate bodily functions to manage heat generation and loss. This balance, termed thermoregulation, is essential for maintaining internal temperature stability in the face of changing external temperatures or increased heat from exercise.

Sweating and its evaporation from the skin are key to shedding excess heat, especially during physical activity. Yet, this process's efficiency is affected by external factors and what one wears. Layering clothes like hoodies can hinder heat release by trapping moisture and limiting air movement around the skin, possibly causing higher body temperatures and a quicker heart rate as the body attempts to move heat from its core to the surface (Galvin 2003). Moreover, the process of thermoregulation operates through a negative feedback loop, in which the body responds to changes in temperature by initiating processes to revert to its normal temperature range. This regulatory mechanism guarantees that if the body's temperature deviates from its ideal point, it automatically takes corrective measures, such as enhancing or reducing heat generation or dissipation, to restore balance.

Additionally, the material and fit of clothing are also critical for effective thermoregulation. Non-breathable or overly insulating fabrics and tight clothing can block sweat evaporation and constrict blood flow, affecting temperature regulation efficiency. Therefore, selecting appropriate attire for exercise is important for accurate evaluation of its effects on the body's physiological responses (Andrej A. 2008).

This study investigates how different insulation levels, through wearing various numbers of hoodies, influence heart rate changes and return to normal heart rate after exercise. It aims to enhance our understanding of how clothing insulation interacts with physical effort and thermoregulatory responses, offering guidance for optimal exercise practices.

Research question  

What are the effects of completing 30 burpees in 3 minutes while wearing different numbers of cotton hoodies (0, 2, 4), and how do the changes in insulation levels affect the heart rate and the time it takes to recover to baseline heart rate (heart rate homeostasis)?

Hypothesis 

Increased Insulation Leads to Higher Heart Rate:

• With each additional layer of hoodie worn (0, 2, and 4 layers), the participants' heart rates during the physical activity will increase significantly; this is due to the body's increased effort to regulate its temperature under the added insulation, or clothing, which in turn requires more energy expenditure and increases the heart rate.

Prolonged Recovery Time:

• The time it takes for participants' heart rates to return to their baseline (original) levels after the exercise will be longer with each added layer of insulation. The extra insulation could slow down the body’s ability to release heat, prolonging the process of returning to the original heart rate level. 

Variables 

Independent Variable: 

• The number of hoodies worn when exercising 

  • This allows for a direct examination of how additional layers influence the body's effort to regulate temperature and maintain homeostasis during physical activity.

Dependent Variable: 

• The heart rate of the subject 

  • Monitoring heart rate provides insight into the cardiovascular system’s workload and the body’s overall movement level, which are indicative of how well the body manages heat produced during exercise.

• The time it takes for the heart rate to come back to its original range

  • According to the different insulation levels, or the number of hoodies worn in this experiment, the amount of time required for the heart rate after exercise to return to its original range.

Constants: 

• Room Temperature 

  • Keeping the room temperature constant ensures that external thermal conditions do not influence the body's heat loss or gain, allowing any changes in heart rate to be attributed to the insulation effect of the hoodies rather than environmental temperature fluctuations.

  • Control Value: CID regular temperature: around 25 to 28 degrees Celsius

• Thickness of Hoodies 

  • Standardizing hoodie thickness ensures that the insulation level is consistent across all tests.

  • Control Value: 0.4mm for each cotton hoodie

    
    

• Exercise Level 

  • Maintaining the same level of physical activity for all subjects ensures that the heat generated by muscular activity is consistent.

  • Control Value: 30 burpees for each subject

Control Group: 

Benchmark: a subject wears 0 hoodies and completes 30 burpees at a 25 degrees Celsius room

• This comparison allows researchers to isolate the effect of wearing hoodies from the basic physiological response to performing burpees, providing a clearer understanding of how additional insulation affects heart rate and thermoregulation.

Methodology 

1.     Participants and Materials 

Selection Criteria: Recruit a sample of healthy 10^th grade boys with a range of fitness levels. Ensure participants have no known cardiovascular problems and are accustomed to moderate physical activity. 

Sample Size: Determine based on the resources available and statistical power analysis to ensure results are meaningful. 

Heart Rate Monitors: To accurately measure participants' heart rates before, during, and after performing burpees. 

Hoodies: Identical hoodies in terms of material, weight, and size to standardize across participants. 

Timer: To ensure each participant performs burpees for the same duration. 

2.     Pre-experiment 

Preliminary Assessment: Measure resting heart rates of participants to establish a baseline. 

Warm-Up: Have participants perform a standard set of exercises to minimize the risk of injury during the experiment. 

3.     Experimental Procedure 

1. The experimenter measures and takes notes of the original heart rate of the subject by employing a hand grip heart rate monitor. 

2. The subject then, in the order of 0,2, and 4, wears hoodies, adding a layer of insulation to investigate its effect on the human’s heart rate and homeostasis. 

3. The subject now executes 30 burpees in a limited 3-minute time, increasing the physical activity level. 

4. By utilizing the heart rate monitor again, the researcher measures and takes notes of the heart rate after the exercise. The researcher should measure the heart rate once each minute until the subject reaches its original heart rate. 

5. The experimenter measures and records the time it takes for the subject’s heart rate to come back to its original status. 

6. Continue this process with 4 other subjects to increase the reliability in the results and to prevent any anomalies. 

Raw Data

Tables:

Heart Rate of Each Subject After Completing 30 Burpees (BPM)

							Heart Rate N Minutes After Completing 30 Burpees
Number of Hoodies	S1	S2	S3	S4	S5	AVG	STDEV
0	138	137	142	137	136	138	2.345
2	159	153	151	156	153	154.4	3.130
4	176	172	169	171	168	171.2	3.114

Time It Takes for Each Subject to Recover to Normal Heart Rate (s)

							Time It Takes for Each Subject to Recover to Normal Heart Rate
Number of Hoodies	S1	S2	S3	S4	S5	AVG	STDEV
0	45	59	68	53	72	59.4	9.810
2	78	90	84	102	102	91.2	9.6
4	105	132	119	124	129	121.8	9.495

*S = Subject

Processed Data

Graphs:

Observation

The graph depicting the change in heart rate after exercising with different numbers of hoodies shows a progressive increase in heart rate with an increased number of hoodies worn. Subjects with 0 hoodies have the lowest heart rates post-exercise, while those with 4 hoodies have the highest. The error bars, which represent the variability within each group, indicate some degree of individual variation, yet the overall trend supports the hypothesis that insulation affects heart rate during exercise.

Furthermore, the second graph indicates that the time to recover to a normal heart rate after exercising increases with the number of hoodies worn. Subjects without hoodies recover the quickest, and those with 4 hoodies take the longest. The error bars in this graph are wider for subjects wearing hoodies, suggesting more variability in recovery time within these groups. Despite this variability, the trend is clear and consistent across the groups.

Conclusion

Research Question: How does the number of hoodies worn affect our heart rate homeostasis when doing 30 burpees? 

Claim

The data from the experiment suggests that wearing additional layers of insulation in the form of hoodies during exercise significantly increases heart rate response and prolongs the recovery time to baseline levels in 10th grade boys. Specifically, the experiment shows a dose-response and directly proportional relationship where the increase in the number of hoodies worn correlates with an increase in heart rate immediately after exercise and a longer duration for heart rate to return to resting levels. This implies that the body’s ability to regulate temperature and maintain homeostasis is challenged by the extra insulation, thereby affecting cardiovascular strain and recovery dynamics after exercise.

Evidence

The data shows a clear and consistent increase in heart rate after exercise that correlates with the number of hoodies worn. For example, subjects wearing no hoodies had a significantly lower immediate post-exercise heart rate (with an average around 137-138 beats per minute) compared to those wearing two hoodies (with an average around 153-159 beats per minute) and four hoodies (with an average around 169-176 beats per minute).

Longer Recovery Time with More Insulation: The data also indicates that the time taken for heart rate to return to normal levels is longer as the number of hoodies increases. Subjects with no hoodies returned to their normal heart rate faster (in 45 to 72 seconds) than those wearing two hoodies (78 to 102 seconds), and recovery times were even longer for those wearing four hoodies (105 to 132 seconds).

The error bars on the graph indicate the range of variability within each measurement, showing that while there is some natural variability, the overall effect of insulation on heart rate and recovery time is clear and significant.

Reasoning

Thermoregulation and Heat Dissipation:

The body exerts more effort to cool itself when insulation is heightened. Additional layers confine heat, causing a rise in body temperature, which prompts the heart to circulate more blood to the skin's surface to dissipate heat.

Evaporative Cooling Mechanism:

Sweating serves as a key method for regulating body temperature. For this process to effectively eliminate heat, the sweat needs to evaporate from the skin. The extended recovery period associated with greater insulation could be due to the hoodies retaining moisture and restricting evaporation, thereby impairing the body's cooling efficiency.

Vasodilation:

The extra layers provided by hoodies might have led the body to keep blood vessels dilated for extended times after exercising, in an ongoing effort to release heat, resulting in a prolonged elevation of the heart rate.

Fit and Individual Differences:

The uniformity in the responses among individuals suggests that the insulating impact of the clothing is significant enough to override differences in fitness levels, metabolic rates, and the efficiency of thermoregulation among people.

Evaluation

Limitations

1. Sample Size and Diversity: The experiment is limited to 10th grade boys, which may not be representative of the broader population, including different ages, fitness levels, and genders.

2. Measurement Precision: The use of hand grip heart rate monitors might not provide the most precise measurements of heart rate, especially if the contact with the sensor is inconsistent (did this happen quite often).

3. Insulation Levels: Using only 0,2, and 4 hoodies limites the granularity of the data. It assumes a linear relationship without exploring potential threshold effects or non-linear responses.

Improvements

1. Increase Sample Size and Diversity: To generalize findings, the experiment could include a larger and more diverse sample, with subjects of different ages, genders, fitness levels, and backgrounds

2. Use More Accurate Instruments: Employing more sophisticated heart rate monitoring devices could improve the accuracy of the measurements.

3. Expanded Insulation Levels: Including a wider range of insulation levels could provide a more detailed understanding of the relationship between insulation and physiological response; for example, experimenting with an extreme number of hoodies will exhibit clearer data that strongly supports the hypothesis.

Citations

1. Gavin TP. Clothing and thermoregulation during exercise. Sports Med. 2003;33(13):941-7. doi: 10.2165/00007256-200333130-00001. PMID: 14606923.

   
   

2. Romanovsky, Andrej A. "The thermoregulation system and how it works." Handbook of clinical neurology 156 (2018): 3-43.