Exploratory Research on Relationship between Cardiorespiratory Fitness and Cognition Among Older Adults: Post-Exercise Hemodynamic Assessment = 운동 후 혈역학 반응 측정을 이용한 노년층의 심폐체력과 인지기능 간 관계 탐색 연구

국문 초록 (Abstract)

많은 연구들이 신체활동이 심혈관 건강, 체력, 인지기능 등에 좋은 영향을 미치는 것을 확인하였다. 현 연구의 목적은 체력과 인지기능 간에 주목할 만한 유의미한 관계가 있는지 검증하는 것이다.

실험 1
연구에 참여한 피험자는 모두 노인층으로, 55살 이상이다. 피험자들은 서울대병원 신경과 외래환자이며, 67명이 참가하였다. 그중, 실험 기준에 부합하는 66명의 자료를 분석하였다. 심폐체력 측정을 위하여, 스텝운동과 의자운동을 시행하였다. 운동 후에 측정된 혈압 및 심박수의 값이 심폐체력을 반영하며, 운동 전의 값에서 감산한 값이 심폐체력의 지표로 사용 되어, 운동 1분후와의 차이를 상승 그리고 운동 1분후와 운동 3분후와의 차이를 회복1, 운동전과 운동 3분후와의 차이를 회복2로 정하고 측정하였다. 인지기능을 측정하기위해, 집행기능 및 시지각 기능을 측정하는 Trail Making Test (TMT) A유형과 B유형의 시험, 작업기억 및 집중력을 측정하는 Digit Span Forward (DSF) 유형과 Backward (DSB) 유형의 시험, 영상기억 수행테스트가 사용 되었다. 영상기억수행시험(ICM)은 두 가지 유형의 블록으로 나눠져 있는데, 숫자 블록은 피험자에게 방향키가 가리키는 숫자를 맞추도록 하고, 색깔블록은 색깔을 맞추도록 요구된다. 각각의 블록들은 다시 세 가지 조건, pre 300ms, pre 100ms, post 100ms, 으로 이루어져있다. 이중, post 100ms 조건은 영상기억기능을 반영하고, 나머지 조건들은 집중력을 반영한다.
모든 운동 후 혈압 및 심박 지표에서 횟수로 측정된 체력과의 유의미한 상관관계가 발견되었다(p<0.05). 스텝퍼운동 후 상승된 혈압 및 심박 값과 인지기능결과와는 유의미한 상관관계가 발견되지 않았지만, 의자운동후의 혈압 및 심박지표와는 유의미한 상관관계가 발견되었다 (p<0.05).

실험 2
연구에 참여한 피험자는 모두 노인층으로, 55살 이상이다. 피험자들은 서울대병원 신경과 외래환자이며, 155명이 참가하였다. 그중, 실험 기준에 부합하는 67명의 자료를 분석하였다. 실험 2 와 순서와 운동 및 인지기능 시험은 동일하며, 심페 체력 측정 방법만 바뀌었다. 심박 마다 모니터링 된 혈압과 혈압 변이 값과 운동 전의 혈압과 혈압 변이 값의 차이를 구하여, 혈압 및 혈압 변화량과 심폐체력과 비교하였고, 인지기능과의 상관관계를 파악하였다.
인지 기능 점수 결과와 혈역학 적 생체 신호에 관해서 나이, 성별, 교육년수를 제어변수로 놓고 편상관 분석을 한 결과, 혈압변이 변화량을 제외하고, 나머지 모든 혈압지표 및 체력 값과 인지기능과의 유의미한 상관관계가 발견되었다(p<0.05). 운동전과 운동 횟수와 인지기능 간에도 부분적으로 유의미한 상관관계가 확인되었다(p<0.05).
노년층에서 얻은 혈압지표와 체력의 상관관계를 통하여, 심폐체력의 측정 방법론으로서의 사용가능성을 제시하였고, 이를 통하여 측정한 심폐체력과 인지기능의 상관관계를 파악하였다.

다국어 초록 (Multilingual Abstract)

Numerous studies have examined the positive effects of exercise on physical health and cognition. Such effects are often discovered with assessing cardiorespiratory fitness (CRF), which is health-related fitness. Since the CRF reflects cardiovascular and respiratory health, the cardiovascular response to exercise is used in many studies to assess CRF. CRF has been frequently reported to be closely associated with brain function. Especially for preventing cognitive deterioration among older adults, exercise and physical fitness effects on cognition are heavily researched. The association between CRF and the neural system is linked with cardiovascular function. For cerebral blood flow (CBF) circulation, the heart’s role as a source provider because it provides a driving force for CBF to the brain by contracting its muscle. Both the heart rate (HR) and blood pressure (BP) represent cardiovascular fitness, but only HR index is used as CRF assessment.
This study aims to examine whether there is a positive relationship between physical fitness and cognitive function. In addition, the second purpose of this study is to investigate if blood pressure (BP) reflects CRF to suggest BP as a new CRF assessment. Two experiments were conducted with different cardiovascular measurements. In the first experiment, HR and BP were measured while only BPs were measured with the continuous beat-to-beat monitoring device in the second experiment.
Experiment 1
Method
The data of 65 participants (71.88 ± 6.98) were used for analysis. All of the subjects participated in cognitive assessments (trail making tests, digit span tests, & iconic memory task), exercise tests (stepper & chair-stand exercises, and cardiovascular assessment (pre- and post-exercise cardiovascular measurement). To discover the immediate recovery reflects CRF, the BP and HR were measured 1 min and 3 min after exercise.
Results
Only the HR positively correlated with fitness (p<.05). The CRF related cognitive functions were discovered as iconic memory, attention, working memory, and visuoperceptual skills. Although there were inconsistent results found among the significant correlation results after chair exercise, all other significantly correlated CRF indices positively associated with cognitive performances(p<.05).

Experiment2
Method
The data of 67 participants (73.46 ± 6.98) were used for analysis. The procedure is the same as experiment 1 except for the measurement time of cardiovascular assessment. The blood pressure was monitored from the start and end of the experiment. The 3 min of BP and BPV recovery were analyzed.
Results
No significant correlation was found between fitness and BP & BPV recoveries. However, significant results found in the correlation between cognition and CRF and between cognition and pre-exercise BP. The CRF positively associated with iconic memory, attention, working memory, and visuoperceptual skills(p<.05). The pre-exercise BPs inversely correlated with iconic memory and attention. Lower the resting BP relates to better cognition, which corresponds to previous findings.
Conclusion
BP was not examined to reflect CRF based on the current findings, but HR was discovered to reflect CRF. Although the current study's attempt to suggest a new CRF assessment was failed, another hypothesis that CRF is significantly associated with cognition was partially supported. Iconic memory, attention, working memory, and visuoperceptual controls were discovered as associated with CRF, but executive function was not examined. However, the significant results found in the broad range of cognitive functions are helpful for future research on CRF and cognition. Besides, by modifying the study design, BP will be examined to reflect CRF with valid methods.

목차 (Table of Contents)

• 1. Introduction 1
• 1.1 Research Background 1
• 1.2 Purpose of Research 2
• 2. Review of Literature 3
• 2.1 Physiological Outcomes of Exercise 3
• 2.1.1 Exercise and Fitness 3
• 2.1.2 Cardiorespiratory Fitness and
• Cardiovascular System 3
• 2.1.3 Cerebral Blood Flow as a Bridge
• Between Brain and Heart 4
• 2.2 Fitness and cognition 5
• 2.3 Post-Exercise Hemodynamic Responses and CRF 7
• 2.3.1 Autonomic Nervous System:
• Mediator between Fitness and Heart 7
• 2.3.2 CRF Assessment 8
• 2.3.3 Hemodynamic Parameters: HR and BP 9
• 2.3.4 BP and CRF 10
• 3. Methodology Background 11
• 3.1 Post-exercise Hemodynamic Measurement 11
• 3.2 Study Designs 14
• 4. Experiment 1 16
• 4.1 Methodology 16
• 4.1.1 Participants 16
• 4.1.2 Cognitive Assessment 16
• 4.1.3 Cardiorespiratory Fitness Assessment 20
• 4.1.4 Procedure 21
• 4.1.5 Statistical Analysis 21
• 4.2 Results 23
• 4.2.1 Demographic Characteristics 23
• 4.2.2 Correlation between
• post-exercise hemodynamic responses
• and exercise performances 25
• 4.2.3 Correlation between
• Cognition and Cardiorespiratory Fitness 28
• 5. Experiment 2 38
• 5.1 Methodology 38
• 5.1.1 Participants 38
• 5.1.2. Cognitive Assessment 38
• 5.1.3. Cardiorespiratory Assessment 38
• 5.1.4. Continuous Beat-to-Beat
• Cardiovascular Assessment 39
• 5.1.5 Statistical Analysis 41
• 5.2 Results 41
• 5.2.1 Demographic Characteristics 41
• 5.2.2. Correlation between
• post-exercise hemodynamic responses
• and exercise performances 44
• 5.2.3 Correlation between
• Cognition and Cardiorespiratory Fitness 45
• 5.2.4 Correlation between
• Cognition and Pre-Exercise Blood Pressure 56
• 6. Discussion 61
• 6.1 Contributions 65
• 6.2 Limitations 65
• References 67
• Abstract in Korean 79