To determine the extent to which well-trained endurance athletes practice the dietary recommendations for maximizing muscle glycogen resynthesis, collegiate cross-country runners (14 males and 10 females) kept 4-day dietary and activity records during a training period and a competitive period in the regular cross-country season. The mean running mileages for men and women were 16.0 ± 1.0 and 10.7 ± 0.6 km/day during the training period and 14.6 ± 0.8 and 8.7 ± 0.5 km/day during the competitive period, respectively. Males reported adequate energy intake in both phases, whereas females fell short of the RDA. However, the percentage of calories from carbohydrate was found to be inadequate (< 60%) for male runners. Although female runners derived 65-67% of calories from carbohydrate, the daily amount of carbohydrate taken was insufficient (< 10 g/kg body weight). Carbohydrate was ingested immediately postexercise approximately 50% of the time or less, with even far less taken in suggested quantities (−1 g carbohydrate/kg body weight). There were no significant differences in dietary trends between training and competitive phases. The results suggest that these endurance athletes were not practicing the recommended feeding regimen for optimal muscle glycogen restoration.
Jill A. Tanaka, Hirofumi Tanaka and William Landis
Saowaluck Suntraluck, Hirofumi Tanaka and Daroonwan Suksom
Microvascular and macrovascular dysfunction plays an important role in the pathogenesis of diabetic vascular disease. Twenty-nine older patients with type 2 diabetes were randomly assigned into the land-based (LB; n = 14) or water-based (WB; n = 15) groups. Both groups completed supervised aerobic cycling exercises three times per week for 12 weeks. The WB group performed cycling exercise training in warm water (36 °C) immersed to the hip level. After 12 weeks, blood glucose concentration and insulin resistance did not change but hemoglobin A1c levels decreased (P < .05) in both groups. Plasma nitric oxide concentrations increased (P < .05) in both groups. Flow-mediated dilation in the popliteal artery increased and arterial stiffness decreased (P < .05) in both exercise groups. Indices of microvascular reactivity improved (P < .05) only in the WB group. The benefits of warm water-based training were similar in general, and superior in some measures, to the more established land-based cycling exercise.
Napasakorn Chuensiri, Hirofumi Tanaka and Daroonwan Suksom
To determine the acute effects of high-intensity intermittent exercise (HIIE) on vascular function.
Lean (n = 18, BMI = 17.1 ± 0.7) and obese (n = 17, BMI = 25.4 ± 0.8) prepubescent boys aged 10.2 ± 0.2 years were studied. HIIE consisted of 8 sets of 20 s of cycle ergometry at 100, 130, and 170% of VO2peak alternating with 10 s of rests.
The obese group had higher (p < .05) body mass, BMI, body fat percentage, waist-hip ratio than the lean group. Carotid artery wall thickness and arterial stiffness as assessed by brachial-ankle pulse wave velocity (baPWV) were greater in the obese than in the lean group (p < .05). Brachial artery flow-mediated dilation (FMD) was not different between the groups. Total energy expenditure increased gradually as the exercise intensity increased in both groups (p < .05). The obese group had significantly greater total energy expenditure in all three HIIE intensities than the lean group. FMD tended to be higher and baPWV lower as the exercise intensity increased in both groups. Only the HIIE at 170% demonstrated greater FMD compared with the baseline in both groups. baPWV decreased significantly after HIIE at 130 and 170% VO2peak in both groups.
Supramaximal HIIE can be a feasible exercise modality for improving vascular function in obese prepubescent boys. Future exercise intervention studies are warranted.
Douglas R. Seals, Kevin D. Monahan, Christopher Bell, Hirofumi Tanaka and Pamela P. Jones
Tonic vagal modulation of cardiac period (R-R interval) decreases with advancing age, but is greater in middle-aged and older adults who habitually perform aerobic exercise compared with their sedentary peers. Cardiovagal baroreflex sensitivity also declines markedly with age in sedentary adults but only 50% as much in regularly exercising adults. In previously sedentary middle-aged and older adults, a 3-month program of moderate aerobic exercise increases cardiovagal baroreflex sensitivity by 25%. Tonic (basal) sympathetic nervous system (SNS) activity increases with advancing age in both sedentary and habitually exercising adults. Despite this, SNS b-adrenergic support of energy metabolism (resting metabolic rate-RMR) declines with age in sedentary individuals. However, SNS b-adrenergic support of RMR is maintained with age inenduranceexercise-trainedadultsandthereforeismuchgreaterinmiddle-aged and older individuals who exercise regularly compared with their sedentary peers. Thus, regular aerobic (endurance) exercise modulates selective age associated impairments in autonomic nervous system-physiological function.
Stacy D. Hunter, Mandeep S. Dhindsa, Emily Cunningham, Takashi Tarumi, Mohammed Alkatan, Nantinee Nualnim and Hirofumi Tanaka
Obesity is associated with arterial stiffening and diminished quality of life. Bikram yoga may be a feasible alternative to traditional exercise among obese individuals. Accordingly, the purpose of this study was to investigate the impact of Bikram yoga, a heated style of hatha yoga, on arterial stiffness in normal and overweight/obese adults.
Forty-three (23 normal body mass index or BMI; 20 overweight/obese) apparently healthy participants completed an 8-week Bikram yoga intervention. Body composition was estimated via dual energy x-ray absorptiometry, arterial stiffness was measured via brachialankle pulse wave velocity, and health-related quality of life was assessed via RAND 36-Item Short Form survey at baseline and at the end of the 8-week intervention.
After the intervention, brachial-ankle pulse wave velocity decreased (P < .05) in overweight/obese participants while no such changes were observed in normal BMI participants. In the quality of life measures, emotional well-being improved (P < .05) in both groups, and general health improved (P < .05) only in the normal weight BMI group.
Bikram yoga ameliorates arterial stiffness in overweight/obese adults and can positively impact quality of life regardless of BMI.
Hun-young Park, Sang-seok Nam, Hirofumi Tanaka and Dong-jun Lee
The aim of this study was to investigate hemodynamic, hematological, and immunological responses to prolonged submaximal cycle ergometer exercise at a simulated altitude of 3000 m in pubescent girls.
Ten girls, 12.8 ± 1.0 years old, exercised on a cycle ergometer for 60 min at a work rate corresponding to 50% maximal oxygen consumption measured at sea level, under two environmental conditions; sea level (normoxia) and a simulated 3000 m altitude (normobaric hypoxia).
There were no significant differences in tidal volume, ventilation, oxygen consumption, cardiac output, stroke volume, and heart rate between the two exercise conditions. However, reticulocyte, adrenocorticotropic hormone, and cortisol concentrations increased significantly from pre- to postexercise in the hypoxic environment. Leukocyte and T-cell count increased and B-cell count decreased after exercise under both conditions. There were no significant changes in natural killer cell count.
Our simulated hypoxic environment provided a mild environmental stressor that did not impose a heavy burden on the cardiovascular, hematological, or immunological functions during submaximal exercise in pubescent girls.