Acute responses and muscle damage in different high-intensity interval running protocols.

AIM: Our study aimed to evaluate the acute responses and exercise--induced muscle damage of five different high--intensity interval training (HIT) protocols adjusted by the maximum velocity obtained in the 30--15 Intermittent Fitness Test (V IFT ). METHODS: Sixteen well--trained intermittent sport players (mean ± SD;; age, 24.6 ± 2.7 years; V̇O 2max , 58.3 ± 5.9 ml∙min∙kg --1 ) participated in five different HIT protocols separated by six days in between (P 240 : 4×4 min at 80% V IFT ; P 120 : 7×2 min at 85%; P 30 : 2×10×30 s at 90%; P 15 : 3×9×15 s at 95%; P 5 : 4×6×5 s sprints). Blood lactate (La), blood pH, serum creatinkinase (CK), heart rate (HR), session rating of perceived exertion (session--RPE), delayed onset muscle soreness (DOMS) and countermovement jump (CMJ) height were measured. RESULTS: A significant main effect for protocol ( p < 0.05) was found for the acute responses of HR, session-RPE and La with values increasing in longer intervals from P 15 to P 120 and P 240 while blood pH responded inversely. In contrast, P 5 produced the highest La concentration and blood pH decreases. 24 h post exercise CK, DOMS and the decrease in CMJ height were significantly higher after P 5 compared to all other protocols ( p < 0.05). CONCLUSION: HIT protocols of different interval duration and intensity result in varying acute physiological and perceptual demands and exercise--induced muscle damage. Longer intervals with submaximal intensity lead to higher acute cardio circulatory responses, whereas sprint protocols induce the highest muscle damage and muscle soreness.

Immunology of Varicella Immunization in the elderly.

OBJECTIVE: To review the varicella-zoster virus (VZV) and herpes zoster disease and to summarize published reports on the use of the live-attenuated varicella zoster vaccine to enhance cell-mediated immunity in elderly individuals. DATA SOURCE: A MEDLINE search (1966-August 1999) for English-language clinical studies and review articles pertaining to VZV and the live-attenuated varicella vaccine was conducted; references obtained from these publications were subsequently reviewed for additional relevant articles. STUDY SELECTION AND DATA EXTRACTION: Representative clinical trials were summarized and relevant information was selected to assist in the understanding of VZV, the subsequent immune response, and the live-attenuated varicella vaccine. DATA SYNTHESIS: The physiologic, age-related decline in VZV cell-mediated immunity has been shown to be restored on administration of live-attenuated varicella vaccine. Various studies report serum anti-VZV antibody concentrations, and production of interferon-gamma were increased following vaccination. Concentrations subsequently returned to baseline one year after vaccination. Increase in responder cell frequency, a measure of cell-mediated immunity, has been reported to last up to four years after vaccination, at concentrations similar or superior to those observed following herpes zoster. CONCLUSIONS: Enhancement of cell-mediated immune response in elderly individuals through vaccination with live-attenuated varicella vaccine is a possible measure to protect this population from herpes zoster and to attenuate its complications. A summary of immunogenicity studies to identify the immune response to live-attenuated varicella vaccine in the elderly is presented. The absolute clinical significance, as well as appropriate administration guidelines of this prophylactic intervention, will become evident following forthcoming large, masked, placebo-controlled trials.

Adaptive changes of dopamine-D2 receptors in rat brain following ethanol withdrawal: a quantitative autoradiographic investigation.

The effect of subchronic treatment with two doses of ethanol (5 and 10 vol% drinking fluid) on the density of dopamine-D2 receptors was investigated at two different phases of withdrawal, namely 24 h and 5 days after the cessation of the ethanol application. The number of dopamine-D2 receptors was affected in regions receiving projections from both the substantia nigra as well as the ventral tegmentum. Twenty-four hours after the replacement of the ethanol solution by water, a dose-dependent decrease of D2 receptors was found in all regions (N. caudatus dorsalis, medialis and ventralis, N. accumbens lateralis and medialis, tuberculum olfactorium) and most of the analyzed planes [interaural 7.7-10.2 according to the atlas of Paxinos and Watson (35)]. At day 5 of withdrawal, the number of dopamine-D2 receptors of the animals treated with 5 vol% ethanol reached the level of water controls in most planes. In contrast, two- to three-fold higher numbers were detected in animals treated with the higher dose. Only in the most caudal parts of the investigated regions, was the number of receptors decreased with the higher dose. The mesocorticolimbic system seems to be less sensitive to the effects of ethanol than the nigrostriatal neurones. The findings of the present study suggest an increased activity of dopaminergic neurons with an adaptive reduction of dopamine-D2 receptors during the subchronic treatment with ethanol during the first day(s) of withdrawal. This phase is followed by a reduced turnover rate for up to 7 days (21). The reduced activity of dopaminergic neurones induces a compensatory increase of the number of receptors.(ABSTRACT TRUNCATED AT 250 WORDS)