Concurrent cardiovascular and resistance training in healthy older adults.

PURPOSE: The recommendations for exercise training and physical activity for older adults include cardiovascular and resistance training components (CVT and RT, respectively). The purpose of the present investigation was to compare the fitness benefits of concurrent CVT and RT with those attained through an equivalent duration of CVT or RT alone. METHODS: Thirty-six participants (ages 60-84) were assigned to a control group or to one of three exercise treatment groups. The treatment groups exercised three times per week for 12 wk using RT (N = 11), CVT (N = 10), or CVT and RT (BOTH, N = 9). Pre- and post-training, participants performed a submaximal exercise test (GXT), five repetition-maximum strength tests (5RM), and the AAHPERD functional fitness test for older adults. RESULTS: All exercise treatment groups revealed lower resting heart rate and rate-pressure product; lower exercise diastolic blood pressure and rating of perceived exertion; increased GXT duration; increased leg, back, and shoulder 5RM scores; and improved AAHPERD flexibility, coordination, and cardiovascular endurance scores. The exercise treatment groups responded differently on the following: RT and BOTH enhanced arm and chest strength more than CVT; and BOTH enhanced AAHPERD strength and agility scores more than CVT or RT. CONCLUSIONS: Concurrent CVT and RT is as effective in eliciting improvements in cardiovascular fitness and 5RM performance as CVT or RT, respectively. Moreover, incorporating both CVT and RT in exercise programs for older adults may be more effective in optimizing aspects of functional fitness than programs that involve only one component.

Modification of forearm vascular function following short-term handgrip exercise training.

This study examined the effect of low (25% of maximum voluntary contraction) and high (75% of maximum voluntary contraction) intensity short-term handgrip exercise training on localized vascular function. Forearm blood flow was evaluated in twenty-eight healthy men (age: 23 +/- 4.3) pre- and post-training in both forearms at rest, following forearm occlusion and following forearm occlusion combined with handgrip exercise using strain gauge plethysmography. The 4-week program consisted of non-dominant handgrip exercise performed 5 d/wk for 20 min at either low or high intensity. Following training a significant increase in forearm blood flow was noted for the nondominant arm in both groups after forearm occlusion (low intensity group: 16.51%; high intensity group: 20.72%; p = 0.001) and forearm occlusion combined with handgrip exercise (low intensity group: 17.71%; high intensity group: 29.27%; p = 0.001). No significant group by test interaction (p = 0.632) was found. These data show improved unilateral vasodilatory responsiveness after short-term handgrip training. In addition, the degree of change is most notable following the greatest vasodilatory stimulus. Lastly, a lack of group by treatment interaction suggests the change may be independent of training stimulus.

Influence of head-down and lateral decubitus neck flexion on heart rate variability.

The purpose of this study was to examine the response of heart rate variability (HRV), a noninvasive index of autonomic control, to head-down neck flexion (HDNF), which engages both otoliths and neck muscle afferents, and to lateral decubitus neck flexion (LNF), in which neck afferents are activated, whereas otolith afferent input is not. HRV and forearm blood flow were evaluated in participants lying prone, during HDNF, lying in the lateral decubitus position, and during LNF. Compared with the prone position, HDNF resulted in lower high-frequency (46.9 +/- 7.1 vs. 62.3 +/- 6.2) and higher low-frequency (53.1 +/- 7.1 vs. 37.7 +/- 6.2) power, expressed as normalized units, along with higher low-frequency-to-high-frequency ratio (1.65 +/- 0.3 vs. 0.78 +/- 0.2), whereas LNF resulted in no alterations in HRV indexes. Furthermore, there were no significant differences in forearm blood flow or vascular resistance among any of the positions. Our data suggest that otolith organs influence autonomic modulation of the heart, supporting previous studies reporting that HDNF elicits increased sympathetic outflow. These data further suggest that HDNF results in a parasympathetic withdrawal from the heart in addition to sympathetic activation.

Vagal modulation of the heart and central hemodynamics during handgrip exercise.

Blood pressure and continuous electrocardiogram recordings were obtained from 12 participants during spontaneous breathing (SB1), dynamic handgrip exercise at 20% (HG(20)) of maximal voluntary contraction (MVC), and spontaneous breathing (SB2) and dynamic handgrip exercise at 60% (HG(60)) of MVC. Repeated-measures ANOVAs were used to examine the effects of the exercise conditions on mean arterial pressure (MAP), on mean standard deviation (SDNN), and on the coefficient of variation of R-R intervals. The mean R-R interval responded to exercise in an intensity-dependent manner. SDNN decreased with exercise but was not intensity dependent. Coefficient of variation decreased during HG(20), and MAP increased following HG(60). These data are consistent with the notion that changes in cardiovascular function with low-intensity exercise are primarily mediated by parasympathetic withdrawal, and as exercise intensity increases, additional cardiovascular reactivity is mediated by increased sympathetic outflow. The change in the coefficient of variation from rest to exercise was unique in comparison to the changes in SDNN, and this merits further investigation.

Physical activity, mental stress, and short-term heart rate variability in patients with ischemic heart disease.

BACKGROUND: Among the general population, mental stress seems to depress heart rate variability (HRV), and physical activity level seems to be positively associated with HRV. However, the extent to which these relationships exist among patients with ischemic heart disease is not clear. Therefore, this study investigated the association between level of physical activity and HRV among patients with ischemic heart disease during conditions of paced breathing and the Stroop Color-Word Conflict Test (Stroop). METHODS: Forty-two patients with ischemic heart disease were assigned to groups based on their documented volume of aerobic activity: Low = 1.008-2.646 kJ/wk; Mod = 3.024-3.864 kJ/wk; and High = 4.284-7.560 kJ/wk. These groups did not differ in age, body mass index, or hostility as determined by the Minnesota Multiphasic Personality Inventory. Time and frequency domain measures of HRV were derived from electrocardiograph data obtained during 5 minutes of paced respiratory control and 5 minutes of performing the Stroop Test. RESULTS: There was a main effect of activity level (P < 0.05) on the standard deviation of R-wave to R-wave intervals (SDNN), total spectral power, and high-frequency power such that these dependent variables were greater in the High group than in the Low or Mod group. Furthermore, there was a main effect of the test condition on SDNN and total power, both of which were lower during the Stroop Test as compared to paced respiratory control. CONCLUSIONS: The results indicate that, among patients with ischemic heart disease, a high level of physical activity is associated with higher HRV, but is not related to stress reactivity as measured by HRV.

Class III antiarrhythmic effects of LY-190147 on defibrillation threshold.

Defibrillation strength shocks delivered within an action potential (AP) delay repolarization. Shock-induced AP duration extension (APDE) may prolong refractoriness and terminate or prevent reinitiation of reentry, favoring defibrillation. This study examined LY-190147 (LY) effects on defibrillation threshold (DFT) in 11 dogs. Ventricular effective refractory period (VERP) and epicardial monophasic AP duration at 75% repolarization (APD75) were recorded at 300-, 400-, 500-, and 600-ms pacing cycle length (CL). APDE was measured as the time to 50% repolarization after a DFT strength shock delivered at 50, 25, and 0 ms before or 25 ms after VERP during pacing at 300 ms CL in 4 of the dogs. We made all recordings before drug administration and after infusions of 0.03, 0.3, and 3.0 mg/kg LY, using 1.5-h dosing intervals. LY lowered DFT in a saturating dose-response manner whether expressed as shock peak voltage (V) or energy. LY decreased DFT-V from 357 +/- 77 V before drug to 331 +/- 60 V (-6 +/- 12%), 290 +/- 43 V (-17 +/- 13%, p < 0.001), and 312 +/- 45 V (-11 +/- 12%, p < 0.05) at 0.03, 0.3, and 3.0 mg/kg, respectively. Similarly, LY treatment decreased defibrillation energy requirements from 6.9 +/- 2.7 J before drug by 7 +/- 25%, 26 +/- 24%, and 12 +/- 25% at the same doses. At 300-600 ms CL, LY prolonged APD75 by an average of 10 +/- 8% at 0.03 mg/kg, 17 +/- 6% at 0.3 mg/kg, and 24 +/- 9% at 3 mg/kg. At these CL, LY prolonged VERP by an average of 4 +/- 6% at 0.03 mg/kg, 15 +/- 10% at 0.3 mg/kg, and 11 +/- 9% at 3 mg/kg. APDE was increased from 62 +/- 9 ms before to 68 +/- 14, 80 +/- 16 (p < 0.001) and 72 +/- 13 ms (p < 0.05) at 0.03, 0.3, and 3.0 mg/kg LY, respectively. Therefore, LY prolonged VERP and APDE and affected DFT in the same saturating dose-response manner. LY may facilitate defibrillation by increasing the duration of postshock refractoriness.

Effect of early feeding on the postburn hypermetabolic response in rats.

The effect of early enteral feeding on the hypermetabolic response following burn injury in a rat burn model has been investigated. The rates of heat production and partitioned heat loss were determined on the fourteenth postburn day for five treatment groups: I) burn, fed rat chow ad libitum starting 2 hours postburn; II) burn, fed by gastrostomy beginning 2 hours postburn; III) burn, fed by gastrostomy, delayed until 72 hours postburn; IV) controls, fed by gastrostomy 2 hours post anesthesia; and V) controls, fed rat chow ad libitum 2 hours post anesthesia. Gastrostomy feedings delivered 175 kcal/kg.day. The mean rates of heat production and heat loss for the three burn groups did not differ significantly whether rats were fed chow ad libitum, or by gastrostomy early or late. Contrary to previous studies using a guinea pig model, method and timing of feeding in this burned rat model had no significant effect on the postburn increment in the rate of heat loss and the corresponding increment in the rate of heat production.

Differences between pair and bulk hydrophobic interactions.

It is now well known that the pair interaction between two hydrocarbon molecules in water has distinctly different properties from the bulk hydrophobic interaction familiar to the biochemist, which is modeled by the transfer of a hydrocarbon from aqueous solutions to pure liquid hydrocarbon. We consider experimental data for pair interactions, which have been fitted by a simple empirical potential function, and point out some of their properties. (i) Surface free energy and cosphere overlap models, of the type considered until now, cannot reproduce correctly both the pair and bulk hydrophobic interactions. (ii) Pair interactions though still attractive are strikingly weaker in aqueous solution than in the gas phase, in contrast to the usual view of hydrophobic interactions. (iii) For pair interactions in water, the solvent-separated configuration is less important than the contact configuration if the hydrocarbon has more than two carbon atoms.

The effect of early feeding on postburn hypermetabolism.

The effect of early enteral feeding upon postburn hypermetabolism was studied on the fourteenth postburn day using five groups of rats. Feeding methods and treatments for the groups were: I) rat chow ad libitum at 2 hours postburn (PB); II) fed early by gastrostomy at 2 hours PB; III) fed late by gastrostomy at 72 hours PB; IV) fed early by gastrostomy--shaved control; V) rat chow ad libitum--shaved control. Gastrostomy feedings delivered 175 kcal/kg.day. The rates of heat production and heat loss did not differ significantly between any of the burn groups, whether fed ad libitum, or early or late by way of gastrostomy. The burned rats fed ad libitum gained significantly more weight than the rats fed late by gastrostomy. Contrary to previous studies using a guinea pig model, method and timing of feeding had no demonstrable effect on the postburn increment in heat loss and the secondary increment in heat production following thermal injury in rats.

Use of technique metal in preclinical education: effect on student products and performance.

As a result of the theft of dental students' gold issue, use of a less expensive technique alloy in a preclinical course was evaluated as a substitute for conventional gold alloy. Three-unit all-metal fixed partial dentures were fabricated by sophomore dental students as part of a fixed prosthodontics preclinical technique course. One group of students used a conventional gold alloy and a second group used a technique alloy. Except for solder joint appearance, similarities in student performance and perceptions indicated that technique alloy is an acceptable, cost-effective substitute for gold in preclinical courses.

T cell subsets and cellular immunity in end-stage renal disease.

The T lymphocyte population was studied by immunofluorescent staining with monoclonal antibodies and laser flow cytometry in the blood of 50 patients with end-stage renal disease undergoing long-term maintenance intermittent hemodialysis. The absolute number of T cells was lower in patients receiving dialysis for more than one year (p less than 0.001), as was the absolute count of helper T cells (p less than 0.005). In patients under 30 years of age, the absolute number of helper T cells was markedly reduced, whereas the number of suppressor/cytotoxic T lymphocytes was not changed. In patients between the ages of 30 and 60 years, both helper and suppressor cells were significantly reduced. In patients over 60 years of age, only the number of helper T cells was reduced. The in vitro response of patients' lymphocytes was reduced both in the mixed lymphocyte reaction (p less than 0.01) and after phytohemagglutinin stimulation (p less than 0.001). Natural killer cytotoxicity of patients' peripheral blood mononuclear cells, however, was unaffected.

Dimensions of effective preclinical teaching.

The purpose of this study was to identify the factors underlying dental students' evaluations of preclinical instruction. Ninety sophomore students in academic year 1979-80 and 74 sophomore students in academic year 1980-81 rated five preclinical instructors in a fixed prosthodontic technique course. At the end of the course, prior to final examinations, students received a 24-item evaluation instrument designed to assess preclinical teaching behavior. All items were rated on a 5-point scale, with response options ranging from no agreement to strong agreement. Factor analytic techniques were used to identify common sources of variation among items. Results indicate that 22 of the 24 items correspond to two underlying, stable dimensions that summarize preclinical teaching effectiveness, teaching style, and orientation toward students. The discussion compares teaching effectiveness dimensions identified in dental education studies with dimensions identified in studies of college instruction.

Hollow silicone abturators for patients after total maxillectomy.

One technical approach for the treatment of a patient after complete removal of the hard palate and other supportive structures has been presented. This technique offers a means of obtaining a detailed impression of the defect and promptly provides the patient with a lightweight and flexible tissue-tolerant obturator. The patient can ultimately be provided with a hollow dental prosthesis attached to a removable hollow obturator.