현대사회의 과학기술 발달로 인해 증가된 좌식생활은 신체활동과 독립적으로 심혈관질환 위험과 사망률을 증가시키며 혈관기능장애를 유발하는 것으로 알려져 있다. 이에 앉아 있는 동안 간헐적으로 운동을 하는 좌식차단이 좌식으로 인한 혈관기능 감소에 보호적인 역할을 한다고 보고되고 있다. 하지만 선행연구에서는 대부분 유산소 운동을 통한 좌식차단의 효과를 확인하였으며, 저항성 운동을 이용한 간헐적 좌식차단의 효과는 잘 알려져 있지 않다. 따라서 본 연구의 목적은 유산소 운동과 저항성 운동을 이용한 간헐적 좌식차단이 고지방식이 섭취 후 건강한 성인의 혈관 및 대사기능에 미치는 효과를 비교하고자 하였다. 본 연구는 14명의 건강한 성인 남녀(남:8명, 나이:24±2세, 체질량지수: 22.0±2.4kg/m2)가 최소 72시간의 간격으로 세 가지 처치에 모두 참여하는 무작위 교차설계로 진행되었다. 연구 참여자들은 고지방 식이 후 4시간 동안의 좌식 중 유산소 운동처치(스텝운동, 1시간 간격, 5분), 저항성 운동처치(5가지 상·하체 저항운동, 1시간 간격, 5분)와 통제처치(4시간 좌식)에 참여하였다. 대사기능(혈당, 중성지방), 혈역학적 지표(경동맥과 외측대퇴동맥의 혈류량, 혈류전단속도 및 진동성 전단 지표(oscillatory shear index))와 혈압 및 동맥경직도를 좌식 전과 좌식 중 1시간 간격으로 측정하였으며, 혈관 내피세포기능은 상완동맥 내피세포 의존 혈관 확장능력(flow-mediated dilation)을 좌식 전과 좌식 2시간, 4시간에 측정하였다. 고지방식이 섭취 후 4시간의 좌식은 내피세포 의존 혈관 확장능력을 유의하게 감소시켰다(7.4±0.7% to 6.4±0.7% to 5.0±0.7%). 반면에, 운동을 통한 좌식차단은 좌식에 의한 내피세포 기능 감소를 억제시키는 경향이 나타났으나 시간과 처치간의 유의한 상호작용이 나타나지 않았다(유산소 운동처치: 7.8±0.7% to 7.0±0.7% to 7.3±0.7%, 저항성 운동처치: 7.5±0.7% to 7.3±0.6% to 6.7±0.7%, 상호작용 p = 0.561). 유산소 운동과 저항성 운동을 통한 간헐적 좌식차단은 모두 외측대퇴동맥의 혈류량과 혈류전단속도를 통제처치에 비해 증가시켰다 (상호작용 p < 0.001, p = 0.009, 각각). 특히, 유산소 운동은 저항성 운동보다 외측대퇴동맥의 혈류량 및 전단속도를 더 많이 증가시켰으며 (상호작용 p = 0.003, p = 0.043, 각각) 진동성 전단 지표가 더 낮게 나타났다(처치 p = 0.011). 그러나, 운동을 통한 간헐적 좌식차단은 좌식으로 인한 경동맥 혈류 및 전단속도 증가와 고지방 식이 섭취 후 혈당과 중성지방 증가에 긍정적인 효과를 제공하지 못했다. 결론적으로, 운동을 통한 간헐적 좌식차단은 고지방식이 섭취 후 장시간 좌식 중 하지혈관의 혈류량과 전단속도를 증가시켰다. 이러한 효과는 유산소 운동에서 더 크게 나타났으나, 저항성 운동을 통한 간헐적 좌식차단도 좌식에 의한 혈관기능 저하에 보호적 효과를 하는 것으로 나타났다.
While interrupting prolonged sitting with aerobic exercise has been demonstrated to attenuate endothelial dysfunction and postprandial metabolism, less is known about the effect of interrupting prolonged sitting with resistance exercise. Therefore, the purpose of the study was to compare the effects of resistance exercise and aerobic exercise as a strategy for interrupting prolonged sitting on vascular and metabolic function after a high-fat meal in healthy adults. Using a randomized, crossover study design, fourteen healthy young adults (8 males, 24±2 years old, body mass index: 22.0±2.4 kg/m2) participated in three trials separated by at least 72 hours. Participants consumed a high-fat meal, followed by a 4-hour sitting, during which participants interrupted prolonged sitting with either aerobic exercise (AEB, 5 minutes of step exercise every hour), resistance exercise (REB, 5 minutes of resistance exercise every hour), or remained seated (SIT, uninterrupted sitting). Plasma glucose and triglycerides, as well as, blood flow and shear rate in a superficial femoral artery and a carotid artery, brachial and central blood pressure, and arterial stiffness were measured at baseline and every hour after a high-fat meal, while brachial artery flow-mediated dilation (FMD) was measured at baseline and at 2 and 4 hours after a high fat meal. Prolonged sitting after a high-fat meal significantly decreased brachial artery FMD and both AEB and REB did not attenuate a decrease in FMD without a significant interaction effect (AEB: 7.8±0.7% to 7.0±0.7% to 7.3±0.7%, REB: 7.5±0.7% to 7.3±0.6% to 6.7±0.7%, SIT: 7.4±0.7% to 6.4±0.7% to 5.0±0.7%, interaction effect: p = 0.561). Superficial femoral artery blood flow and mean shear rate increased in AEB and REB compared to SIT (interaction effects: p < 0.001 and p = 0.009, respectively). The increases in blood flow and mean shear rate were greater in AEB than in REB (interaction effects: p = 0.003 and p = 0.043, respectively) and an oscillatory shear index in superficial femoral artery was lower in AEB than in REB (trial effect: p = 0.011). Both AEB and REB did not attenuate sitting-induced decreases in blood flow and shear rate in carotid artery and increases in plasma glucose and triglycerides following a high-fat meal. These findings have provided evidence that interrupting prolonged sitting after intake of a high-fat meal with either aerobic and resistance exercise was effective in improving basal blood flow and shear rate in the lower-limb artery in young health adults, with a greater benefit observed with aerobic exercise.
1. Introduction 1Background 1Purpose 6Hypotheses 6Operational definitions 72. Literature Review 8Vascular function and cardiovascular disease 8Endothelial function 8Arterial stiffness 10Prolonged sitting and vascular dysfunction 11High-fat meal and vascular dysfunction 14Effects of interrupting prolonged sitting 18Vascular function 18Metabolic function 21Summary and conclusion 243. Methods 25Participants 25Experimental design 25Measurements 28Brachial artery flow-mediated dilation 28Blood flow, vascular conductance, and shear rate 30Metabolic function 31Brachial and central blood pressure and arterial stiffness 31Other measurements 33Statistical analysis 34Sample size calculation 34Data analysis 354. Results 36PART Ⅰ. Effects of a 4-hour prolonged sitting on vascular and metabolic function 38PART Ⅱ. Effects of interrupting prolonged sitting with exercise breaks on vascular and metabolic function after a g high-fat meal 44PART Ⅲ. Effects of different types of exercise on attenuated vascular and metabolic dysfunction induced by sitting: aerobic exercise vs. resistance exercise 535. Discussion 60PART Ⅰ. Effects of a 4-hour prolonged sitting on vascular and metabolic function 60PART Ⅱ. Effects of interrupting prolonged sitting with exercise breaks on vascular and metabolic function after a high fat meal 66PART Ⅲ. Effects of different types of exercise on attenuated vascular and metabolic dysfunction induced by sitting: aerobic exercise vs. resistance exercise 73Limitations 76Future Direction 77Conclusions 78References 79국문초록 97