Correlation Study Between Bicycle Ownership Status and Physical Activity, Time of Sitting, Overweight or Obesity / 中国循环杂志

Objective: To assess the relationship between bicycle ownership status and physical activity, time of sitting, overweight or obesity in China. Methods: Based on the information of China cohort from Prospective Urban Rural Epidemiology (PURE) study, we conducted a cross-sectional description. Multivariable linear and multivariable Logistic regression analysis were respectively used to distinguish the differences of physical activity, time of sitting, overweight or obesity status between bicycle owners and non-bicycle owners. Results: A total of 42 677 participants were analyzed, the average age was (51.23±9.72) years including 40.9% male. There were 27 744 (65.0%) bicycle owners, their MET-min/week for total physical activity, work, transportation,domestic and recreation time were 2513.00 (1114.00, 5271.00), 444.00 (0.00, 735.00), 420.00 (0.00, 990.00), 600.00 (180.00,1260.00) and 198.00 (0.00, 693.00) respectively; time of sitting was (1397.03±832.13) min/week and waist circumference was (81.03±10.53) cm. With adjusted potential confounders, bicycle owners had more transportation activity, while less total physical activity, work, domestic and recreation time than non-bicycle owners; bicycle owner had more time of sitting and less risk of obesity; BMI and waist-to-hip ratio were similar between bicycle owners and non-bicycle owners. Conclusion: Bicycle owners had more transportation related physical activity and less risk of obesity; while the total physical activity, domestic and recreation related physical activity might be reduced in them.

Comparison of Cardiorespiratory Responses Between Surya Namaskar and Bicycle Exercise at Similar Energy Expenditure Level.

Surya Namaskar (SN), a popular traditional Indian yogic practice called “Sun Salutations”, includes practice of twelve physical postures involving alternate backward bending and forward bending postures. The practice of twelve postures in succession makes one round of its practice. Many people practise it as part of their daily physical fitness regimen. No study is available to compare cardiorespiratory responses of SN with bicycle exercise (BE). 20 healthy Yoga instructors practicing various Yogic practices including SN since last 7-8 years participated in the study. They performed SN in the laboratory according to their customary daily practice routine. The subject also performed incremental load bicycle exercise test till exhaustion on their second visit for measuring their 􀀅 V O2 max. SN and BE were compared at three similar exercise intensity levels in terms of % of 􀀅 V O2 max. The exercise intensities were light (10-20% 􀀅 V O2 max), moderate (21-40% 􀀅 V O2 max) and high intensities (41-50% 􀀅 V O2 max). Heart rate at high work intensity was significantly higher in BE than SN (P<.001). Ventilation and carbon dioxide output were significantly higher in BE than SN at high exercise intensity (P<0.001). Overall, cardiorespiratory stress is less in SN than BE at similar work intensities

Pattern of deoxygenation in vastus lateralis and rectus femoris muscles during a ramp-loaded cycling / 体力科学

The purpose of this study was to compare changes in oxygenation in the Vastus Lateralis (VL) and Rectus Femoris (RF) muscles during a ramp-loaded bicycle exercise. Twelve healthy males participated in the experiment. The test consisted of a leg arterial occlusion at rest and a ramp-loaded exercise (20 watts/min) using a bicycle ergometer until exhaustion. The changes in deoxygenation in each muscle was measured by near infrared spectrometer (NIRS) . The probes of NIRS were placed on VL and RF approximately 12 cm above the right knee. Oxy-Hb/Mb signals from NIRS were calculated as 100% at rest, with 0 % being the lowest value during the leg arterial occlusion. Pulmonary gas exchanges (VE, VO<SUB>2</SUB>, VCO<SUB>2</SUB>) were measured with an expiratory gas analyzer. In 10 subjects, muscle oxygenation level in VL decreased linearly until the deoxygenation limiting point (DOLP) -the point in exercise at which the deoxygenation rate decreases noticeably. However, in 2 subjects, the DOLP was not detected, and the muscle oxygenation level decreased linearly until exhaustion. The muscle oxygenation level in RF also decreased linearly until 70%VO<SUB>2</SUB>max, although the deoxygenation rate was smaller than that in VL. Thereafter, the muscle oxygenation level in RF continued to decrease until exhaustion. No DOLP was found in any subjects in RF. Compared with the muscle oxygenation level in RF at any points during the exercise, those in VL were lower until 90%VO<SUB>2</SUB>max (P<0.001) . However, the difference in muscle oxygenation levels between VL and RF at exhaustion was not noted. This study indicated that the patterns of deoxygenation in VL and RF during a ramploaded bicycle exercise were different.