Effect of Physical Activities on Cognitive Function: An Experimental Study that Proves a Positive Relation between Physical Activity, Heart Rate Variability, Reaction Time and Cognitive Process
Effect of Physical Activities on Cognitive Function: An Experimental Study that Proves a Positive Relation between Physical Activity, Heart Rate Variability, Reaction Time and Cognitive Process
تأثير الأنشطة البدنية على الوظائف الفكرية: دراسة تجريبية بيّنت العلاقة الإيجابية بين النشاط البدني وتقلب معدل ضربات القلب ووقت رد الفعل وسير عملية الوظائف الفكرية
آمنة علوش Amena Allouc (*) /محمد الشامي Mohamad El Chami(**)
فاتن رمضان(***) /Faten Ramadanزينب داغر Zainab Dagher(****)
ريم مبدر(*****) / Reem Mobaderفاطمة ليلى (******)Fatima Laila
Abstract
Learning is a complex process that depends on cognitive abilities. It includes functions like attention, memory, and reasoning, and it refers to the capacity of the human brain to process, store, and retrieve information. Cognitive functions are affected by many factors such as physical health, physical exercises, and lifestyle choices such as sleep and eating patterns. Studies have shown several indexes that can be used to study cognitive function such as heart rate variability (HRV) and reaction time (RT). In this research, we aimed to study the effect of physical activity on HRV and RT and consequently on cognitive function. Therefore 20 females from Safir High School of an average age 14 were divided into two groups, one group performed exercising program (GS) and the other group doesn’t do any additional physical activities other than their usual daily activities (GNS). For each female in both groups, a pre and post-measurement for heart rate variability and reaction time were done. The average was calculated for RR, MHR, MIBI, and RMSSD. t-Test was performed between pre and post-values in each group for Heart coherence (HC) and reaction time (RT). The results were an increase in average RR interval, an increase in average HC, and a decrease in average RT in GS only. Significant P-values (<0.05) between pre and post-heart coherence values and pre and post-reaction time values in GS only. In conclusion, physical activity plays a role in enhancing heart coherence, visual reaction time choice and consequently enhances children’s cognitive functions.
Keywords: Physical health, Physical activities, Heart rate variability, Reaction time, Cognitive function.
الملخص
يعتمد التعلّم على قدرات فكرية ويتطلب وظائف عدة مثل الانتباه والذاكرة والتفكير. التعلّم يشير إلى قدرة الدماغ البشري على معالجة المعلومات وتخزينها وإعادة إخراجها. تتأثر الوظائف الفكرية بالعديد من العوامل مثل الصحة البدنية والتمارين الرياضية ونمط الحياة المتبع مثل النوم والغذاء. ذكرت الدراسات العديد من المؤشرات التي يمكن إستخدامها لدراسة حالة الوظائف الفكرية مثال تغيّر معدل ضربات القلب (HRV) والوقت المتطلّب لإجراء ردات الفعل ((RT.
هدفت هذه الدراسة إلى التحقق من مدى تأثير النشاط البدني على معدل ضربات القلب ووقت ردات الفعل وبالتالي استخلاص تأثيرها على الوظائف الفكرية. تم أخذ 20 طالبة من ثانوية السفير بمعدل عمر 14، قسمت الطالبات إلى مجموعتين: الأولى قامت بتنفيذ برنامج تمارين رياضية (GS) والمجموعة الثانية هي المجموعة الضابطة أي لم تقم بأي مجهود أو تمارين إضافية. تم قياس معدل ضربات القلب ووقت ردات الفعل القائم على التحفيز البصري لكل طالبة في كل مجموعة على مرحلتين قبل البدء بالبرنامج الرياضي وبعد الإنتهاء منه. حسبت معدلات RR و MHR و MIBI و RMSSD وحسب t-Test لتوازن القلب (HC) ووقت ردات الفعل في كل مجموعة بين القيمة الأولى قبل النشاط البدني وبعده. كانت النتيجة زيادة في RR و HC ونقص في RT فقط في المجموعة المنفذة للنشاط البدني، و قيمة P المحتسبة تشير إلى وجود عامل مؤثر (أي أقل من 0.05) في المجموعة المنفذة للنشاط البدني.
نستنج من الدراسة التجريبية أن هناك علاقة إيجابية بين النشاط البدني و توازن القلب وردات الفعل والوظائف الفكرية، فالنشاط البدني يعزز توازن القلّب ويقلل الوقت المطلوب للقيام بردة فعل وبالتالي يعزز الوظائف الفكرية والتي بدورها هي حاجة لأداء أكاديمي جيد عند الطلاب.
الكلمات المفتاح: الصحة البدنية ، الأنشطة البدنية ، تقلب معدل ضربات القلب ، وقت رد الفعل ، الوظائف الفكرية.
* ماجستير في علم األعصاب وماجستير إدارة تربوية مجازة في الكيمياء الحياتية – منسقة ومدرسة لمادة الكيمياء في ثانوية السفير. مسؤولة مركز الأبحاث العلمية في ثانوية السفير، الغازية.
Master Neuroscience and Bioinformatics, Master Educational Management and License Biochemistry. Coordinator and teacher for chemistry subject in Safir High School, principle of research center in Safir High School, Ghaziyeh . Amena.allouch@shs.edu.lb
** ديبلوم تعليم في تعليم الفيزياء وإجازة في الفيزياء العامة. منسق مادة الفيزياء وأستاذ تعليم ثانوي في ثانوية السفير، الغازية.
Teaching Diploma in physics education and BS in general physics. Physics coordinator and high school teacher in Safir high school, Ghaziyeh. mohamad.elchami@shs.edu.lb
*** ماجيستير في الكيمياء الفيزيائية – ماجيستير في اإلدارة التربوية – منسقة مادة العلوم في ثانوية السفير، الغازية – أستاذة تعليم ثانوي لمادة الكيمياء في ثانوية السفير، الغازية.
Master’s degree in physical chemistry- Master’s degree in educational Management- Science coordinator at Safir High School, Ghaziyeh- Chemistry High School teacher at Safir High School, Ghaziyeh. faten.ramadan@shs.edu.lb
**** ماجستير في علم وظائف األعضاء – مسؤولة مختبر العلوم في ثانوية السفير، الغازية.
Master’s degree in Physiology, Epigenetics, Differentiation, and Development PHEDD-Science lab supervisor at Safir High School, Ghaziyeh. Zainab.moh.dagher@shs.edu.lb
***** طالبة في المرحلة الثانوية قسم علوم الحياة في ثانوية السفير، الغازية.
High school student in life science department in Safir High School, Ghaziyeh. reem.m.mobader@shs.edu.lb
****** طالبة في المرحلة الثانوية قسم علوم الحياة في ثانوية السفير، الغازية.
High school student in life science department in Safir High School, Ghaziyeh.
Introduction
Throughout generations, a quote has been passed on suggesting that adaptation to the changing environment is the key for survival (Evrengül et al., 2005). Physiologically speaking, the human body possesses what is known as adaptive homeostasis which is a method for modulating the different physiological signs to maintain optimal functioning during mild environmental and psychological stress (Pomatto & Davies, 2017 ; Davies, 2016). Moreover adaptation requires correct interpretation and management of environmental information or in other words need cognitive functions (Petersen R. C., 2004) which are essential to perform both simplest tasks of everyday life and the most complex activities (Murman D. L., 2015).
Heart rate variability HRV is one of the measurable parameters that can indicate adaptations within the autonomic nervous system (ANS) (Schwerdtfeger et al., 2020). Whereas Autonomic nervous system and cardiovascular system are indexes of cognitive functioning (Thayer & Lane, 2009 ; O’donnell et al., 2012) as Forte et al. (2019) emphasized a promising physiological correlate of cognitive functioning is heart rate variability (HRV) that is considered as an index of autonomic control of the heart (orte et al., 2019).
HRV as the name suggests is the measure of the variation of the time intervals that separate two consecutive heart beats (Chen et al., 2022). In other words, even though HRV depends on the heart rate HR, it is inversely correlated with it (Kazmi et al., 2016). Not only does HRV reflect the ANS regulations, but it is also a direct indication of resilience, well-being (Olshansky et al., 2008), and overall self-regulatory capacity.
Several factors can contribute to changes in the value of measured HRV, including cortisol levels (Mishica et al., 2021), respiratory frequency, thermoregulation (Nasim et al., 2011), hypertension and diabetes (Souza et al., 2021), and sleep duration. Physical exercise is also one of the most studied factors when it comes to HRV analysis (Valenzano et al., 2016).
HRV is often measured and monitored through electrocardiography ECG in individuals (Sieciński et al., 2020) during exercise (Cuzzolin et al., 2021) or during rest after physical training workload (Valenzano et al., 2016). When analyzing HRV, several metrics can be taken into consideration, where two main categories arise: time domain indices and frequency domain indices (Evrengül et al., 2005).
Table 1 Description of HRV Metrics, Their Types, and Units of Measurement
| Time domain indices | Frequency domain indices | ||||
| Metric | Definition | Unit of measurement | Metric | Definition | Unit of measurement |
| RR | Time between two consecutive R-peaks in an ECG | ms | VLF | Power in the very low-frequency range (0.0033–0.04 Hz) | Hz |
| SDNN | Standard deviation of all N-N intervals | ms | LF | Power in the low-frequency range (0.04-0.15 Hz) | Hz |
| RMSSD | Square root of the mean of the sum of the squares of the difference between adjacent N-N intervals | ms | HF | Power in the high-frequency range (0.15-0.40 Hz) | Hz |
Starting with the time domain indices, the ECG provides data based on the analysis of the QRS complex. Based on the variation of time between two R peaks in the QRS complex, the RR interval is analyzed (Scherz et al., 2020), such that when the duration between RR intervals increases, HR becomes slower, thus HRV increases (McCraty & Shaffer, 2015). On the other hand, the frequency domain indices in short term HRV measurements are the very low frequency (VLF, 0.0033–0.04 Hz), low frequency (LF, 0.04–0.15 Hz), and high frequency (HF, 0.15–0.40 Hz) (Dong, 2016). In frequency analysis, the dominance of PNS or SNS becomes quantifiable such that LF is associated with SNS, whereas HF is associated with PNS. Consequently, a low value of LF indicates high HRV whereas a high HF value indicates high HRV (Shaffer & Ginsberg, 2017).
Reaction time (RT) is another important method used to study person’s cognitive speed or processing speed (Brebner & Welford, 1980 ; Jensen A.R., 2006). Herman Von Helmholtz emphasized that RT is the nerve conduction velocity, it is the time taken between the stimulation of nerve to muscle contraction (Obrenović et al., 1996). RT is related to the speed of the sensorimotor cycle, starting from initial stimulus, migration of the information through the afferent nerves, production of the response from the central nervous system and at the end the final response (Metin et al., 2016 ; Sant’Ana et al., 2016). There are two types of RT, Simple reaction time (SRT) and complex reaction time (CRT). The SRT is the interval time between stimulus, detection and response (Jayaswal, 2016), while the CRT includes the identification and selection of a response related to various stimuli (Boisgontier et al., 2014). Visual choice reaction time is a type of SRT and it is used to determine the alertness of a person (Obrenović, 1996) that needs efficient execution of several different cognitive processes (Paul Whitney et al., 2010) and RT should be less in certain occupations such as, drivers, pilots, military people, sportsmen, doctors, nursing staff, security guards and so forth (Balakrishnan et al., 2014). This visual choice reaction time has been shown to be affected by several factors including gender, age, physical fitness, biological rhythm and level of fatigue (Baayen and Milin, 2010).
On the other hand physical activity and sports have crucial impact on heart rate variability (HRV) and reaction time. Heart rate variability, coherence, and autonomic nervous system are responsible for regulating heart rate; all of them with reaction time are promising indexes to study the cognitive abilities and other bodily functions. However the effects of the physical activity and sports on these indexes depend on a variety of factors such as the type, the duration and the intensity of exercise.
Inferences from Meta-Analysis showed that physical activities result in significant increases in RR interval and HF power and consequently in HRV in people who are physically inactive (Sandercock et al., 2005). Physical exercise was related to higher heart rate variability and parasympathetic activity in adolescents who were engaged in sports (Cayres et al., 2015). Similar studies showed that heart rate variability is increased due to chronic exercise; especially in endurance trained athletes (Aubert et al., 2001) and that highly trained cyclist have increased heart rate variability indices, reflecting an increase in cardiac vagal control (Pluima et al., 1999).
Reaction time considered as a part of the cognitive control (Jakobsen et al., 2011), is a measure of the time it takes for an individual to respond to a stimulus. Previous studies have found positive relation between cognitive control and aerobic fitness in preadolescents and adults (Westfall et al., 2018). In addition, Westfall showed that this relation is also valid in adolescents (Westfall et al., 2018). In addition to the positive effect of physical activity on HRV, physical activity has proved to enhance reaction time in athlete adolescents by having faster eye-hand visual reaction times than non-athletes (Sediakarsu et al., 2009).
Furthermore, physical activity, sport and decision making are related where the speed of decision making is improved with increased exercise intensity even though results showed that exercise does not affect the accuracy of decision making (Fontana et al., 2009).
Learning is a complex process that depends on cognitive abilities. How it is affected by HRV, reaction time and sport? Cognitive ability includes functions like attention, memory, and reasoning, and it refers to the capacity of the human brain to process, store, and retrieve information. According to Matthias et al. (2016), cognitive ability is one of the most well-researched and consistent predictors of academic achievement at the moment. Academic achievement, as defined by Martinez-Otero (2007), is “the product given by the students, and it is typically expressed through school grades.” A wide range of factors affect learners’ academic achievement. Academic performance appears to be influenced by lifestyle choices such as sleep and eating patterns, as well as physical exercise and screen usage (Edwards, Maucgm & Winkelman, 2011; WY SO, 2013; Stroebele, McNally, Plog, Siegfried, & Hill, 2013; Correa-Burrows, Burrows, Blanco, Reyes, & Gahagan, 2016; Garcia-Hermoso & Marina, 2017).
Numerous studies have demonstrated a beneficial relationship between cognitive processing and heart rate variability (HRV). Lower HRV was specifically linked to poorer performance. It has been proven by many studies that the reaction time (RT) is crucial to the learning process and has an impact on academic success (Taskin C, 2016). Prbhavati et al. (2017) investigated how RT affects the academic performance and did their research on first-year medical students. The results showed that students with faster RTs performed better academically, which they attributed to improved cortical arousal, attention, and processing speed.
Furthermore, physical activity (PA) and exercising have been known to have positive effects on adolescent physical and mental health (Tremblay et al., 2016). Many studies suggest that PA and healthy lifestyle choices may also improve cognitive function and academic performance (Rasberry et al., 2017). According to a recent study, children’s academic success was associated with getting enough physical activity (at least 60 minutes daily) (Zheng W. et al., 2023). Also, it is crucial to note that various exercise programs differ in their effects on children’s cognitive development and physical fitness.
Method
Twenty females from Safir High School of average age 14, were divided into two groups. Group S made up of 9 females who performed an exercising program set by professional athletes “Teacher Hussein Hassoun and Teacher Soubhieh aljoueidi” and Group NS made up of 11 females who didn’t perform any physical activities other than their usual daily activities.
The exercising program consisted of a specific number of jumps using jumping rope distributed over 20 days. The program is given in table 2.
Table 2: Exercising Program
| Days | Number of jumps | Days | Number of jumps |
| Day-1 | 50 | Day-11 | Rest |
| Day-2 | 150 | Day-12 | 150 |
| Day-3 | 90 | Day-13 | 235 |
| Day-4 | 150 | Day-14 | 255 |
| Day-5 | 125 | Day-15 | 150 |
| Day-6 | 140 | Day-16 | 310 |
| Day-7 | 165 | Day-17 | 150 |
| Day-8 | 150 | Day-18 | 350 |
| Day-9 | 200 | Day-19 | Rest |
| Day-10 | Rest | Day-20 | 385 |
HRV parameters and Heart coherence: Heart Coherence (HC) was measured during a resting state before and after the exercising program for the GS and in resting state before and after the end of the duration for the GNS using emWave Pro Plus. emWave Pro Plus is used to measure the subtle beat-to-beat changes in heart rate and to analyze the heart rhythm pattern for coherence. Each female was asked to sit in a rest state while reading a geographical article, ear lobe sensor was used and emWave Pro Plus program was run for 10 minutes.
Figure 1 emWave ProPlus Machine
Reaction time: A pre and post visual choice reaction time assessment was applied by each female using Cognifit visual assessment test. CogniFit’s assessments are available online, are made up of fun, interactive brain games and at the end of each training session, the user automatically receives data in percentage of how much pictures he/she recognized and the reaction time for his/her recognition.
Results
HRV parameters
The chosen HRV parameters were RR, MHR, MIBI, RMSSD. The average of each parameter and that for each group in pre and post- test is shown in figure 2.
Figure 2 HRV average parameters
Heart coherence
t-Test paired two samples for means were used to study the heart coherence data statistically between the pre and post measurements in each group and a scatter plot graph was drawn for HC for each group ( GS and GNS).
Table 3 t-Test paired two samples for means between pre and post HC for each group S and NS
| Data | GS | GNS | ||
| Mean | 32.24444 | 35.57778 | 35.12727 | 34.27273 |
| Variance | 22.56778 | 17.41444 | 31.38218 | 26.16218 |
| Pearson Correlation | 0.680658 | 0.445732 | ||
| Hypothesized Mean Difference | 0 | 0 | ||
| Df | 8 | 10 | ||
| t Stat | -2.77403 | 0.501016 | ||
| P(T<=t) one-tail | 0.012073 | 0.313602 | ||
| t Critical one-tail | 1.859548 | 1.812461 | ||
| P(T<=t) two-tail | 0.024146 | 0.627204 | ||
Figure 3 Scatter plot for HC pre and post values in each group.
Reaction Time
t-Test paired two samples for means where used to study the reaction time data statistically between the two groups (G S and GNS). Table 4 shows the t-test data between the two groups.
Table 4 t-Test reaction time between pre and post assessment for each group S and NS
| Data | GS | GNS | ||
| Pre test | Post test | Pre test | Post test | |
| Mean | 0.845333 | 0.769444 | 0.88725 | 0.802 |
| Variance | 0.011006 | 0.007096 | 0.021658 | 0.019713 |
| Pearson Correlation | 0.875441 | -0.01168 | ||
| Hypothesized Mean Difference | 0 | 0 | ||
| Df | 8 | 7 | ||
| t Stat | 4.440334 | 1.178625 | ||
| P(T<=t) one-tail | 0.001083 | 0.138527 | ||
| t Critical one-tail | 1.859548 | 1.894579 | ||
| P(T<=t) two-tail | 0.002167 | 0.277055 | ||
Discussion and Conclusion
The RR interval decreases as a result of increased sympathetic nervous activity, and increases as a result of increased parasympathetic activity (Billman, 2013). The standard deviation of all NN intervals “SDNN” reflects the measurement of the NN intervals, which is the period between normal-to-normal RR peaks (Kuusela, 2013). Similarly, RMSSD represents the Root mean square of the standard deviation between N-N intervals, and an increase in RMSSD also signifies an increase in HRV. High values of both RMSSD and SDNN imply a dominance of parasympathetic nervous system PNS over the sympathetic nervous system, despite the fact that RMSSD is more affected by the PNS than SDNN (Shaffer et al., 2014). RR interval increased in GS only, which means a decrease in sympathetic nervous activity, and an increase in parasympathetic activity in GS. Average Heart coherence increased in GS only and significant P-value (<0.05) obtained between the pre and post measures of Heart coherence in GS only. This means physical activity enhances heart coherence. Finally reaction time decreased in both groups but only significant value obtained in GS group where significant P-value obtained (<0.05) between pre and post visual choice reaction time. This ensures that physical activity has a positive effect on improving reaction time in other word improve person attention and alertness. All in all physical activity has a crucial role in enhancing heart coherence and reaction time which are good indexes for the improvement of cognitive function.
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