Yoichi Hatamoto

The Effects of Exercise Under Hypoxia on Cognitive Function

Increasing evidence suggests that cognitive function improves during a single bout of moderate exercise. In contrast, exercise under hypoxia may compromise the availability of oxygen. Given that brain function and tissue integrity are dependent on a continuous and sufficient oxygen supply, exercise under hypoxia may impair cognitive function. However, it remains unclear how exercise under hypoxia affects cognitive function. The purpose of this study was to examine the effects of exercise under different levels of hypoxia on cognitive function. Twelve participants performed a cognitive task at rest and during exercise at various fractions of inspired oxygen (FIO2: 0.209, 0.18, and 0.15). Exercise intensity corresponded to 60% of peak oxygen uptake under normoxia. The participants performed a Go/No-Go task requiring executive control. Cognitive function was evaluated using the speed of response (reaction time) and response accuracy. We monitored pulse oximetric saturation (SpO2) and cerebral oxygenation to assess oxygen availability. SpO2 and cerebral oxygenation progressively decreased during exercise as the FIO2 level decreased. Nevertheless, the reaction time in the Go-trial significantly decreased during moderate exercise. Hypoxia did not affect reaction time. Neither exercise nor difference in FIO2 level affected response accuracy. An additional experiment indicated that cognitive function was not altered without exercise. These results suggest that the improvement in cognitive function is attributable to exercise, and that hypoxia has no effects on cognitive function at least under the present experimental condition. Exercise-cognition interaction should be further investigated under various environmental and exercise conditions.

The Relationship between Running Velocity and the Energy Cost of Turning during Running

Ball game players frequently perform changes of direction (CODs) while running; however, there has been little research on the physiological impact of CODs. In particular, the effect of running velocity on the physiological and energy demands of CODs while running has not been clearly determined. The purpose of this study was to examine the relationship between running velocity and the energy cost of a 180°COD and to quantify the energy cost of a 180°COD. Nine male university students (aged 18–22 years) participated in the study. Five shuttle trials were performed in which the subjects were required to run at different velocities (3, 4, 5, 6, 7, and 8 km/h). Each trial consisted of four stages with different turn frequencies (13, 18, 24 and 30 per minute), and each stage lasted 3 minutes. Oxygen consumption was measured during the trial. The energy cost of a COD significantly increased with running velocity (except between 7 and 8 km/h, p = 0.110). The relationship between running velocity and the energy cost of a 180°COD is best represented by a quadratic function (y = −0.012+0.066x +0.008x2, [r = 0.994, p = 0.001]), but is also well represented by a linear (y = −0.228+0.152x, [r = 0.991, p<0.001]). These data suggest that even low running velocities have relatively high physiological demands if the COD frequency increases, and that running velocities affect the physiological demands of CODs. These results also showed that the energy expenditure of COD can be evaluated using only two data points. These results may be useful for estimating the energy expenditure of players during a match and designing shuttle exercise training programs.

A novel method for calculating the energy cost of turning during running

Although changes of direction are one of the essential locomotor patterns in ball sports, the physiological demand of turning during running has not been previously investigated. We proposed a novel approach by which to evaluate the physiological demand of turning. The purposes of this study were to establish a method of measuring the energy expenditure (EE) of a 180° turn during running and to investigate the effect of two different running speeds on the EE of a 180° turn. Eleven young, male participants performed measurement sessions at two different running speeds (4.3 and 5.4 km/hour). Each measurement session consisted of five trials, and each trial had a different frequency of turns. At both running speeds, as the turn frequency increased the gross oxygen consumption (V·O2) also increased linearly (4.3 km/hour, r = 0.973; 5.4 km/hour, r = 0.996). The V·O2 of a turn at 5.4 km/hour (0.55 [SD 0.09] mL/kg) was higher than at 4.3 km/hour (0.34 [SD 0.13] mL/kg) (P < 0.001). We conclude that the gross V·O2 of running at a fixed speed with turns is proportional to turn frequency and that the EE of a turn is different at different running speeds. The Different Frequency Accumulation Method is a useful tool for assessing the physiological demands of complex locomotor activity.

Skipping breakfast reduces energy intake and physical activity in healthy women who are habitual breakfast eaters: A randomized crossover trial

Many epidemiological studies indicate a positive relationship between skipping breakfast (SB) and obesity. However, it is unclear whether SB affects energy intake and physical activity during the day. The objective of the present study was to evaluate the acute effects of SB on energy intake and physical activity under free-living conditions. The present study used a randomized, crossover trial design comparing eating breakfast (EB) and SB days. Twenty lean, healthy women 21-25years old who were habitual breakfast eaters (≥5daysperweek) took part in this study. On EB days, participants were provided a standard breakfast (542kcal). The meals and physical activity after breakfast were under free-living conditions. The meals consisted of foods available at supermarkets, restaurants, and convenience stores. Dietary intake was evaluated by adding values from food labels. Physical activity was assessed using a tri-axial accelerometer. Energy intake at lunch was significantly increased after SB compared with EB (+131±188kcal; p=0.0057). Total energy intake per day was significantly lower after SB compared with EB (-262±428kcal, p=0.013). Physical activity energy expenditure was slightly lower after SB compared with EB (-41±75kcal in the morning, p=0.024; -56±129kcalperday, p=0.064). Step counts and time spent physically active over the whole day were not significantly different between conditions. Skipping breakfast reduced energy intake during the day and morning physical activity in healthy women who were habitual breakfast eaters. The decreased energy expenditure related to physical activity after SB did not exceed the decreased energy intake.

“Slow walking with turns” increases quadriceps and erector spinae muscle activity

[Purpose] To maintain an independent lifestyle, older adults should improve muscle strength and mass, or aerobic capacity. A new exercise pattern, called slow walking with turns, which incorporates turning as an extra load additional to walking. The purpose of this study was to measure oxygen consumption during exercise and muscle activity while turning. [Subjects and Methods] Recreationally active volunteers participated. The participants performed 20 turns per minute while walking back and forth over distances of 1.5 to 3.5 m. We measured oxygen consumption, heart rate, and rating of perceived exertion and performed electromyography during the exercise. [Results] The metabolic equivalents of the exercise were 4.0 ± 0.4 to 6.3 ± 4.0 Mets. Activity was significantly greater in the vastus medialis, vastus lateralis, and erector spinae during the turn phase of slow walking with turns than during the stance phase of treadmill walking. [Conclusion] These findings suggest that slow walking with turns may help to preserve the muscle strength and mass of the trunk and lower limbs that are needed to maintain an independent lifestyle. Slow walking can be performed easily by older people, and in slow walking with turns, the exercise intensity can be adjusted as required for each individual.

Turns in Jogging Increase Energy Expenditure: Proposed Home Exercise forSedentary People

Introduction: We need to reevaluate exercise habits and exercise intensity in order to improve our health. We examined a new exercise pattern termed “slow jogging with turns”, which incorporates turns as an extra load in addition to jogging. This study aim to estimate Mets to create a home-exercise protocol. Subjects and Methods: Ten participants performed slow jogging with turns and treadmill jogging in random order. Slow jogging with turns was performed in six stages at distances of 2.0 to 5.0 m, and treadmill jogging was performed at the same velocities as that for slow jogging with turns. We measured oxygen consumption, heart rate, and rating of perceived exertion. Results: Mets data of slow jogging with turns and treadmill jogging were analyzed using repeated measurement ANOVA with p-value <0.01. Mets during slow jogging with turns were 6.5 ± 0.7 to 10.8 ± 0.9. Mets during slow jogging with turns were significantly higher than those during treadmill jogging at equivalent speeds (p<0.0001). Distance of slow jogging with turns corresponding to Mets was calculated as follows: SJT distance (m) = (target Mets-3.06)/1.5 Conclusion: Slow jogging with turns can increase exercise intensity effectively, and exercise intensity can be adjusted individually by changing jogging distance. This form of exercise can be performed, anytime, anywhere and when done at greater than moderate intensity, helps increase energy expenditure in daily life.

Effect of sleep curtailment on dietary behavior and physical activity: A randomized crossover trial

Our objective was to clarify the effect of sleep curtailment on energy intake (EI) and physical activity under free-living conditions. Participants were 16 healthy women aged 21-22years. A randomized crossover trial design was used to compare a short sleep condition (SS): 4h/night (2:00-6:00) and a control sleep condition (CS): 7h/night (23:00-6:00). Each condition comprised 3 consecutive nights. Sleep duration was assessed using a wristwatch-type accelerometer at home. All living activities except sleeping were free-living. Physical activity was assessed using a tri-axial accelerometer, and was categorized by intensity level (sedentary; sedentary to light; moderate to vigorous). Participants were asked to purchase and consume meals with visible nutrient information. EI was evaluated by adding values from these food labels. Mean sleep duration in the two conditions was significantly different (4.3±0.3 vs. 7.1±0.4h, p<0.01). For the shared wakefulness period in the two conditions (6:00-23:00), step counts and physical activity were not significantly different. Sedentary time (878±61 vs. 727±40min, p<0.01), and sedentary to light-intensity activity time (1122±18 vs. 932±63min, p<0.01) were significantly increased in SS (waking time, 06:00-02:00) compared with CS (waking time, 06:00-23:00). However, these significant effects were clearly attenuated after adjustment for awake time (p>0.05). Total EI was not significantly different between conditions (8.64±0.82 vs. 8.46±1.28MJ, p>0.05), nor were leptin levels (p>0.05), but insulin and cortisol levels after SS were significantly higher than after CS (p<0.05). In this study, physical activity was increased in the SS condition and attributed to differences in awake time between conditions. However, there were no differences in EI. Further studies to investigate the effect of sleep curtailment on weight gain through stress and insulin resistance are necessary.

Effect of exercise timing on elevated postprandial glucose levels

There is no consensus regarding optimal exercise timing for reducing postprandial glucose (PPG). The purpose of the present study was to determine the most effective exercise timing. Eleven participants completed four different exercise patterns 1) no exercise; 2) preprandial exercise (jogging); 3) postprandial exercise; and 4) brief periodic exercise intervention (three sets of 1-min jogging + 30 s of rest, every 30 min, 20 times total) in a random order separated by a minimum of 5 days. Preprandial and postprandial exercise consisted of 20 sets of intermittent exercise (1 min of jogging + 30 s rest per set) repeated 3 times per day. Total daily exercise volume was identical for all three exercise patterns. Exercise intensities were 62.4 ± 12.9% V̇o2peak Blood glucose concentrations were measured continuously throughout each trial for 24 h. After breakfast, peak blood glucose concentrations were lower with brief periodic exercise (99 ± 6 mg/dl) than those with preprandial and postprandial exercise (109 ± 10 and 115 ± 14 mg/dl, respectively, P < 0.05, effect size = 0.517). After lunch, peak glucose concentrations were lower with brief periodic exercise than those with postprandial exercise (97 ± 5 and 108 ± 8 mg/dl, P < 0.05, effect size = 0.484). After dinner, peak glucose concentrations did not significantly differ among exercise patterns. Areas under the curve over 24 h and 2 h postprandially did not differ among exercise patterns. These findings suggest that brief periodic exercise may be more effective than preprandial and postprandial exercise at attenuating PPG in young active individuals.NEW & NOTEWORTHY This was the first study to investigate the effect of different exercise timing (brief periodic vs. preprandial vs. postprandial exercise) on postprandial glucose (PPG) attenuation in active healthy men. We demonstrated that brief periodic exercise attenuated peak PPG levels more than preprandial and postprandial exercise, particularly in the morning. Additionally, PPG rebounded soon after discontinuing postprandial exercise. Thus, brief periodic exercise may be better than preprandial and postprandial exercise at attenuating PPG levels.

Easily performed interval exercise induces to increase in skeletal muscle PGC-1α gene expression

Introduction: Understanding the relationship between PGC-1α expression and exercise is important for developing therapeutic exercise programs focusing on the prevention of lifestyle diseases. The current study examined whether easily performed modearte intensity interval exercise can induce PGC-1α gene expression. Methods: Nine subjects performed cycling in one of three protocols: maximal intensity [MIE: 20 ×1 min with 4 min recovery], high intensity [HIE] and a moderate intensity at anaerobic threshold interval exercise [AIE]. Both HIE and AIE were adjusted to obtain the same exercise volume as MIT performed for 5min including recovery time and repeated 20 times. Results: Increase in PGC-1α mRNA expression was observed in all conditions. with a significant increase in plasma epinephrine. ACC phosphorylation also increased in all condition. Conclusion: These findings suggest that easily performed interval exercise at anaerobic threshold induces PGC1α expression which induce aerobic training adaptation.