Intraocular Pressure Fluctuation during Aerobic Exercise at Different Exercise Intensities.

Few studies have examined the effects of different aerobic-exercise intensities on intraocular-pressure (IOP) changes. This may be important for eye diseases that are impacted by IOP or its fluctuation, including glaucoma, and diabetes that is complicated by diabetic retinopathy. We investigated the effects of low-, moderate-, and high-intensity exercise on IOP in healthy subjects. A submaximal cardiopulmonary exercise test was performed in 18 healthy male subjects, and the maximal oxygen uptake was calculated. The subjects then exercised for 20 min at 30%, 50%, and 70% ·VO2 of maximal oxygen uptake, and their IOP was measured at rest and every 5 min during exercise. Oxygen uptake was monitored using an expiratory gas analyzer during exercise to maintain accurate exercise intensity and adjust exercise load. Oxygen uptake during exercise was significantly higher at all intensities from 5 to 20 min than at rest. IOP was significantly lower at 70% exercise intensity from 5 to 20 min than at rest. A negative correlation existed between IOP and ·VO2. IOP remained unchanged during low- and moderate-intensity exercise but significantly declined during high-intensity exercise compared with that at rest. Although various factors, such as ß-blockers, are involved in IOP decline at rest, a different mechanism is involved in IOP decline during exercise.

Effect of the use of passive body trunk exercise equipment on oxygen consumption and self-efficacy for carrying out exercise in patients with type 2 diabetes.

AIMS/INTRODUCTION: Considering the difficulty in inculcating the habit of exercise among patients with type 2 diabetes, devising an easily maintained means of exercise is preferable. Passive body trunk exercise equipment (PBTE) developed for home use might solve several problems related to exercise therapy, both for patients and clinical staff involved in diabetes treatment; however, its efficacy as a therapeutic exercise device for patients with diabetes has not been ascertained. The purpose of this study was to measure the exercise intensity and self-efficacy of PBTE, and to determine whether PBTE is a useful tool for exercise therapy. MATERIALS AND METHODS: The participants were 20 patients with type 2 diabetes, and the duration of exercise using the PBTE was set to 10 min. Oxygen consumption during exercise was measured, and self-efficacy for continuing to exercise using the PBTE and for walking was evaluated after completion of the study. RESULTS: The average exercise intensity using the PBTE was 1.7 metabolic equivalents, whereas the maximum exercise intensity was an average of 2.0 metabolic equivalents; the reported self-efficacy for continuing to exercise using the PBTE was significantly higher than for walking. CONCLUSIONS: Exercise intensity using the PBTE is similar to low-intensity walking, and thus, it might be a useful therapeutic exercise device for patients with type 2 diabetes. Furthermore, it could be an effective exercise device for diabetes patients who do not have regular exercise habits, especially with reduced motor function or lower leg muscle strength.

Isometric knee extension force in Japanese type 2 diabetic patients without apparent diabetic polyneuropathy: Data from the Multicenter Survey of the Isometric Lower Extremity Strength in Type 2 Diabetes study.

OBJECTIVES: To determine standard reference values for isometric knee extension force using a cohort of Japanese type 2 diabetic patients without diabetic polyneuropathy. METHODS: Patient data were collected from the Multicenter Survey of the Isometric Lower Extremity Strength in Type 2 Diabetes study and compared with previously published data of healthy control subjects. In total, we enrolled 898 patients with type 2 diabetes aged 30-87 years, who did not have diabetic polyneuropathy. The control group included 510 healthy subjects aged 30-88 years. Maximum isometric knee extension force (KEF) values were obtained by using a hand-held dynamometer with belt stabilization. In addition, KEF (kgf) was adjusted for bodyweight (kg) to calculate %KEF. RESULTS: KEF and %KEF decreased with age in both patients with diabetes and healthy control subjects. The mean values of KEF and %KEF in patients with diabetes were reduced by 9.7% and 20.8%, respectively, in males, and by 11.6% and 23.0%, respectively, in females compared to the values in healthy control subjects. CONCLUSION: KEF and %KEF in patients with type 2 diabetes without diabetic polyneuropathy may reduce by approximately 10% and 20%, respectively, compared to these values in healthy control subjects. This study provides reference values for isometric KEF with respect to sex in a population covering a wide age range.

Diabetic polyneuropathy is a risk factor for decline of lower extremity strength in patients with type 2 diabetes.

AIMS/INTRODUCTION: The present study elucidated the effect of diabetic polyneuropathy (DPN) on lower extremity strength in a wide age range of type 2 diabetes patients. MATERIALS AND METHODS: Participants (n = 1,442) were divided into three age groups (30-49 years, 50-69 years and 70-87 years), and comparisons were made separately for each sex. Lower extremity strength was measured in terms of knee extension force (KEF) with a hand-held dynamometer. KEF was compared according to the presence or absence of DPN. Furthermore, the effect of DPN on KEF with other diabetic complications (diabetic retinopathy and diabetic nephropathy), diabetes status (diabetes duration and glycated hemoglobin) and habitual behavior (regular exercise, smoking and drinking behaviors) as explanatory variables was analyzed using multiple regression analysis in several models. RESULTS: The frequency of DPN differed among age groups, ranging from 14.3 to 49.6%, and increasing with age. There was no significant difference in KEF between patients aged 30-49 years with and without DPN. However, among both men and women aged 50-69 years and 70-87 years, patients with DPN showed significantly diminished KEF (11.0-12.9% and 11.9-16.6%, respectively) compared with those without DPN (P < 0.01-0.001). In women aged 50-69 years and 70-87 years, and in men aged 50-69 years, DPN was a significant explanatory variable for KEF in all multiple regression analysis models. CONCLUSION: DPN might reinforce a KEF decline in middle-aged and elderly type 2 diabetes patients.

Regular exercise behavior is related to lower extremity muscle strength in patients with type 2 diabetes: Data from the Multicenter Survey of the Isometric Lower Extremity Strength in Type 2 Diabetes study.

Owing to several contributing factors, continuation of exercise therapy is difficult for patients with type 2 diabetes. One potential factor that has not been well examined is the influence of muscle strength on regular exercise behavior. We examined the relationship between regular exercise behavior and knee extension force (KEF) in 1,442 patients with type 2 diabetes. In sex-specific univariate analysis, KEF was significantly higher in patients who regularly exercised than in patients who did not regularly exercise. However, age, but not exercise behavior, was significantly different between KEF quartiles. Accordingly, KEF and age might strongly influence exercise behavior. In the multivariate analyses using age and other parameters as covariates, KEF was a significant explanatory variable of regular exercise in both men and women, suggesting that muscle strength could influence regular exercise behavior.

The size of motoneurons of the gastrocnemius muscle in rats with diabetes.

Alterations in the number and size of motoneurons were studied in the medial gastrocnemius (MG) motor nucleus of diabetic rats (12 or 22 weeks after injection of storeptozotocin) and age-matched controls. Each group contained 6 animals. MG motoneurons were retrogradely labeled by dextran-fluorescein and the number and size of cell bodies were examined. Significantly fewer labeled MG motoneurons were found in the 22-week diabetic rats as compared with age-matched control animals. The mean soma diameter of MG motoneurons was significantly smaller in the 12- and 22-week diabetic animals. Furthermore the soma size for 22-week diabetic animals was smaller than for 12-week diabetic animals. The distribution of average soma diameters in the MG nucleus of control animals was bimodal; cells with larger average diameter were presumed to be alpha-motoneurons and those with smaller diameters were presumed to be gamma. Compared to control animals, the number of smaller MG motoneurons was reduced in 12 week diabetic animals. By 22 weeks, diabetic animals had no small MG motoneurons and the size distribution became unimodal. We conclude that there is a significant decrease in the absolute number and size of MG motoneurons in diabetic rats, with the possibility that the decrease occurred predominantly among the smaller gamma-motoneurons.

Impaired chronotropic response to exercise in acute myocardial infarction patients with type 2 diabetes mellitus.

This study was undertaken in acute myocardial infarction (AMI) patients with non-insulin-dependent diabetes mellitus (type 2 DM) to investigate their impaired chronotropic response to exercise. Seventy-one AMI subjects entered the study, 30 with type 2 DM and 41 age- and body mass index-matched non-DM (control) patients. One month after the onset of AMI, these patients underwent cardiopulmonary exercise testing on a treadmill under a ramp protocol. Anaerobic threshold (AT) and peak oxygen uptake (peak VO2) were determined as indicators of exercise capacity. Plasma norepinephrine (NE) concentration was measured in blood samples obtained at 2 time points: during pre-exercise rest and immediately after peak exercise. The change in NE concentration during exercise, as an index of sympathetic nervous activity, was calculated as a percentage: deltaNE = [(NE during exercise) - (resting value)]/(resting value) x 100. The change in heart rate (HR) during exercise was calculated as a simple difference: deltaHR = [(peak HR) - (rest HR)]. Index of chronotropic response to exercise was then quantified as the deltaHR/deltaNE during exercise. No significant intergroup differences in ejection fraction at rest or HR at peak exercise were observed. However, VO2 at AT, peak VO2, deltaHR, and deltaHR/deltaNE were significantly lower in the type 2 DM group than in the non-DM group. DeltaHR correlated with VO2 at AT (r = 0.49, P<0.001) and with peak VO2 (r = 0.53, P<0.001) in all subjects. Also, deltaHR/deltaNE correlated with VO2 at AT (r = 0.42, P<0.001) and with peak VO2 (r = 0.44, P<0.001) in all subjects. AMI patients with type 2 DM had impaired cardiopulmonary responses to maximal and submaximal exercise testing and impaired chronotropic response to exercise, even though their cardiac function at rest was similar to that of non-DM AMI patients. The data suggest that one mechanism of impaired cardiopulmonary response to exercise in AMI patients with type 2 DM groups is an impaired chronotropic response.