Mio Nishimaki

Mild Decrease in Skin Temperature Reduces the Heart Rate during Moderate Exercise

The purpose of this study was to investigate the effects of a mild decrease in skin temperature on the heart rate, substrate oxidation, and hormonal responses during exercise. Ten young men performed treadmill exercises approximately 65% of their maximal oxygen uptake for 60 min under two trials: (1) mild body cooling trial, and (2) control trial. Rectal and skin temperatures were recorded during and after exercise. Heart rate and oxygen uptake were monitored during exercise. Blood samples for catecholamine, cortisol, free fatty acid, insulin, and glucose concentrations were collected before, immediately after, and 1 h after exercise. In the mild body cooling trial, mean skin temperature decreased by 1.7 ± 0.7°C in the last minutes of exercise, compared with before exercise. No differences in rectal temperature were seen between the two trials. Although oxygen uptake during exercise and blood parameters did not differ between the trials, heart rate and subjective fatigue during exercise was lower in the mild body cooling trial than in the control trial. This study suggests that mild body cooling reduces the heart rate and subjective fatigue during moderate exercise, but does not affect substrate oxidation or hormonal responses to exercise.

P-56 Maximal fatmax oxidation and fatmax are not associated with endurance performance in trained runners

Objectives Substrate utilisation during exercise is an important factor for endurance performance. Higher availability of fatty acid extends endurance exercise time.1 Additionally, the anaerobic threshold (AT), which is the exercise intensity driven main energy substrate turning fat into carbohydrate, has shown a high correlation with endurance performance.2 Therefore, fat metabolism may be associated with endurance performance. Fatmax, defined as the exercise intensity that elicits the maximal fat oxidation (MFO) rate,3 and MFO are parameters relating to the ability of fat metabolism. Fatmax has been shown to be correlated with the AT4. The aim of current study was to investigate the correlations between MFO and Fatmax and endurance performance in trained runners. Methods Participants included 14 male endurance-trained runners. All participants performed a graded exercise test on a treadmill using a short-time testing protocol which increased 1 Mets per 1 min.5 The maximal oxygen consumption (VO2max), AT, MFO, and Fatmax were measured using indirect calorimetry. The time to exhaustion in the graded exercise test was defined as a measure of endurance performance. The linear relationships between endurance performance and the physiological parameters (VO2max, AT, MFO and Fatmax) were calculated using Pearson’s correlation coefficient. Results Table 1 shows physical characteristics of participants (Table 1). The VO2max and AT were significantly correlated with the time to exhaustion (Fig1 A, B). However, MFO and Fatmax were not significantly correlated with the time to exhaustion (Fig1C, D). Abstract P-56 Table 1 Physical characteristics of participants Conclusions MFO and Fatmax, parameters reflecting the ability for fat metabolism, were not associated with the time to exhaustion in the graded exercise test in trained runners. These findings suggest that fat metabolism may not determine endurance performance. Acknowledgment This study was supported by Grant-in-Aid from the Japan Society for the Promotion of Science Fellows (2016) and the research laboratory allowance of Waseda University. Abstract P-56 Figure 1 Relationship between time to exhaustion in the graded exercise test and physiological parameters (A) VO2 max, (B) AT, (C) MFO and (D) Fatmax- References Hickson RC, Rennie MJ, Conlee RK, Winder WW, Holloszy JO. Effects of increased plasma fatty acids on glycogen utilisation and endurance. Journal of Applied Physiology 1977 Nov:43(5):829–833. Kumagai S, Tanaka K, Matsuura Y, Matsuzaka A, Hirakoba K, Asano K. Relationships of the anaerobic threshold with the 5 km, 10 km, and 10 mile races. European journal of applied physiology and occupational physiology 1982 June:49(1):13–23. Achten J, Gleeson M, Jeukendrup AE. Determination of the exercise intensity that elicits maximal fat oxidation. Medicine and science in sports and exercise 2002 Jan:34(1):92–97. Venables MC, Achten J, Jeukendrup AE. Determinants of fat oxidation during exercise in healthy men and women: a cross-sectional study. Journal of applied physiology 2005 Jan:98(1):160–167. Takagi S, Sakamoto S, Midorikawa T, Konishi M, Katsumura T. Determination of the exercise intensity that elicits maximal fat oxidation in short-time testing. Journal of sports sciences 2014 Jan:32(2):175–182.

P-46 Effects of increased daily physical activity on blood lipids and blood pressure in older adults

Introduction Blood lipids and elevated blood pressure are associated with an increased risk of cardiovascular disease (CVD).1 Although several studies have shown that exercise training improves the risk factors for CVD,2 little is known about the effect of daily physical activity on the risk factors for CVD in older adults. This study aimed to examine the effects of increased daily physical activity during an 8-week intervention period on the levels of blood lipids and blood pressure in older adults. Methods In total, 24 postmenopausal women (age, 70.6 ± 0.7 years; height, 152.4 ± 0.9 cm) were assigned to control (C, n = 12) or physical activity (PA, n = 12) groups. Participants in the PA group were asked to increase their physical activities to more than their usual lifestyle levels for 8 weeks, while those in the control group were asked to maintain their usual lifestyle during the same period. The systolic and diastolic blood pressure of the participants was measured at the baseline and at the end of the intervention. All participants were asked to wear a triaxial accelerometer during the study. Blood samples were taken at the start (baseline) and end of the sessions. Results At the end of the 8-week intervention period, the step counts of the participants in the PA group had increased from 5972 ± 768 steps/day (at the baseline) to 8302 ± 1011 steps/day (P < 0.001). However, no change was observed in moderate to vigorous physical activity after intervention in either group. In addition, blood lipids (triglycerides, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol) and blood pressure did not differ between or within the groups at the baseline and at the end of the intervention. Abstract P-46 Table 1 The change of physical characteristics at base line and after 8 weeks Conclusion These findings indicate that promotion of daily physical activity in older adults is not sufficient to improve their blood lipids and blood pressure. Acknowledgment This work was supported by JSPS KAKENHI Grant Number 15K21434, Meiji Yasuda Life Foundation of Health and Welfare and a Grant-in-Aid from the Japan Society for the Promotion of Science Fellows (2015). References Mehta AK, Doshi RS, Chaudhry ZW, Jacobs DK, Vakil RM, Lee CJ, Bleich SN, Clark JM, Gudzune KA. Benefits of commercial weight-loss programs on blood pressure and lipids: a systematic review. Prev Med 2016 Sep;90:86–99. Fahlman MM1, Boardley D, Lambert CP, Flynn MG. Effects of endurance training and resistance training on plasma lipoprotein profiles in elderly women. J Gerontol A Biol Sci Med Sci 2002 Feb;57(2):B54–60