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PubMed2004

Seasonal and spatial variation of carbohydrates in mistletoes (Viscum album) and the xylem sap of its hosts (Populus x euamericana and Abies alba).

In the present field study we analysed the seasonal pattern of carbohydrate composition and contents in the xylem sap of Viscum album and the xylem sap of a deciduous (Populusxeuramericana) and a coniferous (Abies alba) host tree species. The results were compared with the soluble carbohydrate composition and contents of mistletoe tissues. On both hosts significant amounts of glucose, fructose, and sucrose were found in the xylem sap of Viscum throughout the seasons. The general seasonal pattern of sugar contents, i.e. high concentrations in spring and lower concentrations in other seasons on Populus, and intermediate concentrations throughout the year on Abies, largely reflected the xylem sap carbohydrate composition and contents of the respective host. These observations provide indirect evidence for carbohydrate flux from the xylem sap of the host into the mistletoe. However, in both hosts xylem sap seems to be deviated into the mistletoe without specific control of carbohydrate flux. Differences observed between the seasonal pattern of xylem sap carbohydrate concentrations in Viscum on Populus and Abies may originate from the different time of leaf development of these species. A clear-cut seasonal pattern of soluble carbohydrates was not observed in the leaves of Viscum on both hosts. Still soluble carbohydrates seem to be reallocated from the senescing to the newly developed leaves of Viscum indicating that the seasonal requirement of carbohydrate for growth and development can only completely be met by carbohydrate acquisition from the host and their own photosynthesis.

Journal Article↗
PubMed1996

Effect of prewarming in the cold season on thermoregulatory responses during exercise.

OBJECTIVE: To assess whether thermoregulation in the cold season can be affected by prewarming before exercise. METHODS: Four healthy non-athletic unacclimatised males were exercised to the same degree in summer and winter on a bicycle ergometer without prewarming (experiment 1) and after prewarming by sitting for 30 min in a room at 30 degrees C (experiment 2). During exercise, sweat production and rectal and skin temperatures were measured continuously. RESULTS: There was seasonal variation in sweating capacity and sensitivity and in heat storage during exercise without prewarming (experiment 1). After the subjects were warmed before exercise, there was no such seasonal variation in their sweat rates during exercise at 30 degrees C and 40 degrees C (experiment 2). In both cases, the sweat rate and skin temperature were dependent on the environmental temperature, and the sweat rate and core temperature were dependent on the workload. In the cold season, sweating sensitivity and evaporative cooling response could be enhanced by thermal stimulation. There was no seasonal difference in the relation between evaporative heat loss and metabolic rate in the two thermal conditions. These values did not differ significantly between winter after prewarming and summer (P > 0.05), neither did heat storage and metabolic heat production at various workloads (P > 0.05). CONCLUSIONS: There is adaptation of the thermoregulatory mechanisms during temperature acclimatisation. Body warming enhances not only the heat dissipating activity of the thermoregulatory centre but also the induction of peripheral sweat gland activity. Seasonal change of sweat rate in exercising men can be eliminated through a different type of acclimatisation by prewarming in the cold season.

Acclimatization↗
PubMed1999

Alpha2-macroglobulin and eosinophil cationic protein in the allergic airway mucosa in seasonal allergic rhinitis.

As previously demonstrated in seasonal allergic rhinitis, increased microvascular permeability and eosinophil activation are key features of allergic airway inflammation. In the present study, the hypothesis that exudation of alpha2-macroglobulin may cause the appearance of eosinophil cationic protein (ECP) in the airway lumen was explored. Nasal lavages were carried out using the nasal pool device before and during the pollen season both at baseline and after histamine challenge in 10 children with allergic rhinitis. Nasal lavage fluid levels of alpha2-macroglobulin and ECP were determined. All patients experienced nasal symptoms of allergic rhinitis during the pollen season (p<0.01-0.05). Baseline nasal lavage fluid levels of alpha2-macroglobulin and ECP were increased during the season (p<0.01-0.05) and were found to be well correlated (p<0.0001). Histamine produced concentration-dependent plasma exudation before and during the pollen season, but it was only during the pollen season that this caused an increase in the lavage fluid levels of ECP (p<0.05). These data suggest that exudation of plasma and increased tissue levels and output of eosinophil cationic protein characterize nasal mucosal inflammation in children with seasonal allergic rhinitis. The plasma exudation process in part may account for lumenal entry of eosinophil cationic protein molecules that have been released in mucosal tissue compartments. A combination of induced exudation and nasal lavage may improve the yield of important markers of inflammation in studies of nasal diseases.

Biomarkers↗
PubMed2005

Biochemical and hormonal responses during an intercollegiate football season.

PURPOSE: Changes in biochemical indices of muscle damage and hormonal markers of stress were examined during a competitive intercollegiate football season. METHODS: Twenty-one members of an NCAA Division III football team volunteered to serve as subjects. Eleven of these subjects were starters (ST) and 10 were non-starters (NS). All subjects reported to the Human Performance Laboratory on five separate occasions for blood draws. The first testing session (T1) occurred 1 d before the start of pre-season training camp, the second testing session (T2) occurred at the end of training camp (10 d later), and the other three testing sessions occurred at weeks 3 (T3), 7 (T4), and 11 (T5) of the competitive season. RESULTS: Significant elevations in creatine kinase (CK) were seen from T1 to T2 in both ST and NS. ST had significantly higher CK concentrations at T2 than NS. CK concentrations for both groups returned to baseline levels by T3 and remained constant for the rest of the season. No significant between-group differences were seen in myoglobin (MB), testosterone (TE), cortisol (C), or the testosterone/cortisol ratio (T/C) during the season. A significant main effect for time was seen for C and T/C. C concentrations were significantly lower at T2 than at T1, T3, T4, and T5. Similar changes were also seen for T/C. CONCLUSION: CK elevations seen during T2 appear to reflect the high intensity and physical nature of training camp. However, biochemical and endocrine responses during a season of intercollegiate football competition suggest a degree of sensitization (contact adaptation) of the muscles relating to the repeated traumas occurring during the season.

Adult↗
PubMed2004

Changes in physical fitness parameters during a competitive field hockey season.

Competitive field hockey requires a substantial amount of muscular strength, speed, and cardiovascular endurance. It is unknown how these parameters of physical fitness change between preseason conditioning to postseason recovery. Therefore, Division III female field hockey athletes (n = 13) completed tests of muscular strength, body composition, and maximal oxygen uptake (Vo(2)max) during each phase of their season. Muscular strength was assessed using 1 repetition maximum (RM) leg and bench press tests. Body composition was assessed by anthropometry (skinfolds [SKF]), circumferences ([CC]), and bioelectrical impedance analysis (BIA). Incremental treadmill testing was administered to assess Vo(2)max. Vo(2)max was unchanged during the season, although a trend (p > 0.05) was shown for a higher Vo(2)max during and after the season vs. before the season. Upper- (10%) and lower-body strength (14%) decreased (p > 0.05) during the season. Percent body fat (%BF) from BIA, fat mass (FM) from CC, and body mass index (BMI) were significantly lower (p < 0.05) in-season and postseason vs. preseason. In conclusion, preseason training was effective in decreasing %BF and increasing Vo(2)max, yet muscular strength was lost. Coaches should incorporate more rigorous in-season resistance training to prevent strength decrements. Moreover, these data support the superior levels of muscular strength and leanness in these athletes compared with age-matched peers.

Adult↗
PubMed2005

Changes in physiological and anthropometric characteristics of rugby league players during a competitive season.

This study investigated the physiological and anthropometric characteristics of rugby league players during a competitive season. Sixty-eight rugby league players were allocated into training (n = 52) and nonexercise control (n = 16) groups. The training group participated in 2 field-training sessions per week, with training loads, match loads, and injury rates recorded. Subjects performed measurements of standard anthropometry (height, body mass, and sum of 7 skinfolds), muscular power (vertical jump), speed (10-, 20-, and 40-m sprint), agility (L run), and maximal aerobic power (multistage fitness test) in December (off-season), March (preseason), May (midseason), and August (end season). Increases in maximal aerobic power and muscular power and reductions in skinfold thickness were observed during the early phases of the season when training loads were highest. However, reductions in muscular power and maximal aerobic power and increases in skinfold thickness occurred toward the end of the season, when training loads were lowest and match loads and injury rates were highest. These findings suggest that high overall playing intensity and match loads in end-season matches increase in injury rates in the latter half of the season, and residual fatigue associated with limited recovery between successive matches may compromise the physical development of rugby league players.

Adult↗
PubMed2006

Four weeks of optimal load ballistic resistance training at the end of season attenuates declining jump performance of women volleyball players.

Anecdotal and research evidence is that vertical jump performance declines over the competitive volleyball season. The purpose of this study was to evaluate whether a short period of ballistic resistance training would attenuate this loss. Fourteen collegiate women volleyball players were trained for 11 weeks with periodized traditional and ballistic resistance training. There was a 5.4% decrease (p < 0.05) in approach jump and reach height during the traditional training period (start of season to midseason), and a 5.3% increase (p < 0.05) during the ballistic training period (midseason to end of season), but values were not different from start to end of season. These changes in overall jump performance were reflective of changes in underlying neuromuscular performance variables: in particular, power output and peak velocity during loaded jump squats, countermovement jumps, and drop jumps. During the first 7 weeks of traditional heavy resistance training, it appears that the neuromuscular system is depressed, perhaps by the combination of training, game play, and skills practice precluding adequate recovery. Introduction of a novel training stimulus in the form of ballistic jump squats and reduction of heavy resistance training of the leg extensors stimulated a rebound in performance, in some cases to exceed the athlete's ability at the start of the season. Periodization of in-season training programs similar to that used in this study may provide volleyball players with good vertical jump performance for the crucial end-of-season games.

Adult↗
PubMed1988

Effects of breed, ovarian steroids and season on the pulsatile secretion of LH in ovariectomized ewes.

The effects of season and of oestradiol and progesterone on the tonic secretion of LH were studied in ovariectomized Merino and Suffolk ewes, two breeds which differ markedly in the seasonal pattern of their reproductive activity. In the absence of exogenous steroids, the frequency of LH pulses was lower and the amplitude of the pulses was higher in anoestrus than in the breeding season for Merino and Suffolk ewes 30 days after ovariectomy. In long-term (190 days) ovariectomized ewes, this seasonal change in LH secretion was observed in Suffolk ewes only. During seasonal anoestrus, treatment of ewes with subcutaneous oestradiol-17 beta implants (3, 6 or 12 mm in length) decreased the frequency of LH pulses in a dose-dependent manner, with Suffolk ewes being far more sensitive to the inhibitory effects of oestradiol than Merino ewes. The lowest dose of oestradiol (3 mm) had no effect on the secretion of LH in Merino ewes, but reduced secretion in Suffolk ewes. Treatment of ewes with the highest dose of oestradiol (12 mm) completely abolished LH pulses in Suffolk ewes, whereas infrequent pulses remained evident in Merino ewes. During the breeding season, oestradiol alone had no effect on the pulsatile release of LH in either breed, but in combination with progesterone there was a significant reduction in LH pulse frequency. Progesterone effectively decreased LH secretion in both breeds in both seasons. It was concluded that differences between breeds in the 'depth' of anoestrus could be related to differences in the sensitivity of the hypothalamus to both negative feedback by oestradiol and the direct effects of photoperiod.

Animals↗
PubMed1993

Changes in physical fitness profile in female volleyball players during the competitive season.

Nine members of a female volleyball team served as experimental subjects in order to examine changes in a physical fitness profile during the competitive season consisting of a first season (I) for 10 weeks followed by season II for 11 weeks. The entire season was characterized by 4-5 weekly sessions for playing drills and competitive games and by 2-3 weekly sessions for physical conditioning mostly for strength and explosive strength training. The control group consisted of eight other female volleyball players who trained for physical conditioning during the competitive season 1-2 times per week. The present findings showed that the entire competitive season in experimental subjects led to no changes (from 47.3 +/- 1.7 to 48.1 +/- 3.4 ml x kg-1 x min-1) (n.s.) in VO2max but a significant (p < 0.05) decrease took place in average power in a 30 s anaerobic jumping test. Significant increases took place in the maximal vertical jumping heights in the squat (from 30.3 +/- 1.7 to 31.6 +/- 1.3 cm) (p < 0.05) and in the counter movement jump (from 32.8 +/- 1.6 to 34.3 +/- 1.3 cm) (p < 0.05) as well as in the spike and block jumps (p < 0.05) during competitive season I.(ABSTRACT TRUNCATED AT 250 WORDS)

Anaerobic Threshold↗
PubMed1993

Using maximal and submaximal aerobic variables to monitor elite cyclists during a season.

The purpose of this study was to identify sensitive physiological indicators for monitoring the progress in training state of elite cyclists throughout a training and competition season. Seven elite male cyclists performed maximal oxygen consumption (VO2max) tests and submaximal tests on three or four different occasions during their training and competition season. The submaximal test consisted of three successive 16-min bouts at 150, 200, and 250 W interspersed with rest periods between each load. Pedalling rate varied progressively from 50-120 rpm. Results showed that maximal heart rate (HR), ventilation (Ve), gross mechanical efficiency (MEG), and VO2max did not change during the season. Moreover, ventilation threshold (VT) did not change during the season, nor did HR, Ve, and VO2 at VT. However, changes were found in physiological variables during the submaximal test. HR decreased significantly during the season, as did VO2 (P < 0.05) for a standardized workload. On the other hand, at the higher power outputs (200 W and 250 W) MEG increased during the season. These results suggest that VO2max may not be a good indicator of enhanced capacity in elite cyclists. Rather, a standardized efficiency test during which submaximal variables such as HR, VO2, and MEG are monitored might be a more sensitive indicator of the progress in the training state of elite male cyclists during a training and competition season.

Adaptation, Physiological↗
PubMed1993

Changes in physical fitness profile in female basketball players during the competitive season including explosive type strength training.

Ten female basketball players served as subjects in order to examine changes in a physical fitness profile during a 22-week official competitive season. Specific explosive type strength training (1-2 sessions per week) was utilized throughout the season. The present findings showed that the entire competitive season led to no systematic changes in the maximum oxygen uptake (from 48.0 +/- 6.6 to 47.0 +/- 6.0 ml.kg-1.min-1), in anthropometric characteristics or in maximal isometric force of the leg extensor muscles (from 2567 +/- 490 to 2622 +/- 747 N). However, significant (p < 0.05) increases occurred during the season both in the average power output during the first 15 s work in an anaerobic jumping test and in the maximal vertical jumping heights in the squat jump (from 21.7 +/- 2.3 to 24.2 +/- 2.4 cm) and in the counter movement jump (from 24.9 +/- 2.6 to 26.3 +/- 2.9 cm). A considerable change occurred also in the shape of the isometric force-time curve of the leg extensor muscles so that the times to produce submaximal force level shortened (p < 0.05). The individual changes during the competitive season both in the power output and in the times of rapid force production correlated negatively (p < 0.05) with the individual initial values recorded before the season. The present findings suggest that the prolonged competitive season in the present female basketball players seemingly placed sufficient demands on the athletes in energy production through aerobic processes to maintain their level of VO2max.(ABSTRACT TRUNCATED AT 250 WORDS)

Anaerobiosis↗
PubMed1996

[The incidence of virus respiratory infections in small children in the season 1994-95].

As previously, by antibody fluorescent technique the etiology of viral respiratory infections was determinated in small children hospitalized because of respiratory disease in the epidemic season 1994-95. Data obtained were compared with the results from the preceding season. Among a total of 371 patients, virus infection was detected in 170 (45,8%). Data for the whole season did not distinctly differ from those obtained previously; however, some differences were found in the occurrence of the individual virus infections in consecutive months of the epidemic season. The second (spring) wave of RS virus infections in this season was lower and more extended in time than in the previous seasons. Highest incidence of adenoviruses was observed in July 1995. The incidence of parainfluenza type 4 virus was higher in the disease of small children. In the youngest (below 1 month) age group percent of virus infections was higher, as compared with data from the preceding season.

Age Factors↗
PubMed1996

Characterization of the "seasonal" bulimic patient.

OBJECTIVE: To determine whether bulimia nervosa (BN) patients who experience marked fall/winter worsening in eating behavior and/or mood are otherwise distinct from nonseasonal BN patients. METHODS: We empirically identified "seasonal" and "nonseasonal" groups from a sample of 208 consecutive BN patients completing the Seasonal Pattern Assessment Questionnaire (SPAQ). t Tests were performed to determine if seasonal patients differed from nonseasonal patients with respect to demographic and weight variables, age of onset of symptoms, illness severity, and attitudes and beliefs. RESULTS: Seasonal BN patients exhibited a greater discrepancy between maximum lifetime and current weight, an earlier age of onset of binging, and a higher current monthly binge frequency than did the nonseasonal group. Seasonal patients also scored significantly higher on the Bulimia and Interoceptive Awareness (reflecting lower self-awareness) subscales of the Eating Disorders Inventory (EDI). DISCUSSION: The results suggest that seasonal BN patients may represent a distinct subgroup characterized by a low threshold for binging behavior, greater preoccupation with bulimic behaviors, poor awareness of moods and feelings, and a unique course of illness. More research is needed to confirm these initial findings and to further assess the effectiveness of light therapy for these patients.

Adolescent↗
PubMed2005

Seasonal mood variation in the elderly: the Leiden 85-plus study.

BACKGROUND: The influence of seasonal changes on mood and behaviour is called seasonality. The prevalence of seasonality in elderly subjects is unknown. AIM: To investigate the seasonality pattern in mood and behaviour at old age. METHODS: All subjects from the Leiden 85-plus Study with an MMSE score of 19 or more were assessed for depressive feelings at age 85 and yearly thereafter. The influence of time of the year, duration of sunlight, daylight, and rain on the prevalence of depressive symptoms was assessed using linear mixed models for repeated measurements. RESULTS: There was no significant seasonal pattern in the data (p=0.44). Within each of the four years of observation (85, 86, 87 and 88 years) and all years combined, there was also no significant association between the one-month cumulation of duration of sunlight, daylight, or rain and the score on the GDS (all p-values >0.05). The results of either the one week or three-month accumulation of sunlight, daylight, or rain were comparable to the one-month results. CONCLUSIONS: Estimates of prevalence of seasonality reported in the literature might be overestimated or a remarkable difference between young and old subjects exists.

Affect↗
PubMed1991

Evaluation of seasonality in six clinical populations and two normal populations.

The Seasonal Pattern Assessment Questionnaire (SPAQ) was used to evaluate retrospectively self-reported seasonal changes in mood and behavior (seasonality) of two normal and six clinical populations: patients with winter-seasonal affective disorder (SAD), summer-SAD, eating disorders, bipolar affective disorder, major depressive disorder and subsyndromal winter-SAD. The SPAQ successfully discriminated between groups expected to have high seasonality scores, such as winter-SAD, summer-SAD and subsyndromal winter-SAD, and normal controls. Bipolars and major depressives had normal seasonality scores. Patients with eating disorders had unexpectedly high scores. There was a general tendency for all groups to eat and sleep more and to gain weight in the winter. The implications of these findings are discussed.

Adult↗
PubMedDate not supplied

Seasonal symptom variation in patients with chronic fatigue: comparison with major mood disorders.

The psychobiology of idiopathic fatigue has received renewed interest in the medical literature in recent years. In order to examine the relation between chronic, idiopathic fatigue and specific subtypes of depressive illness, we characterized the pattern and severity of seasonal symptom variation in 73 patients with chronic, idiopathic fatigue, compared to patients with major depression (n = 55), atypical depression (n = 35), and seasonal affective disorder (n = 16) Fifty of the fatigued subjects also met the specific Centers for Disease Control and Prevention case criteria for chronic fatigue syndrome, though this definition was unable to discriminate a distinct subgroup of patients, based on their seasonality scores alone. As a group, the fatigued subjects reported the lowest levels of symptom seasonality of any of the study groups. Further, even in those fatigued subjects with scores in the range of those seen in patients with seasonal affective disorder, seasonality was not reported to be a subjectively distressing problem. These findings lend support to the idea that although chronic fatigue shares some clinical features with certain mood disorders, they are not the same illnesses. These data are also consistent with the emerging view that chronic fatigue represents a heterogeneously determined clinical condition.

Adult↗
PubMed1992

Nasal beclomethasone prevents the seasonal increase in bronchial responsiveness in patients with allergic rhinitis and asthma.

Experimental studies have demonstrated that induction of a nasal allergic reaction can lead to an increase in bronchial responsiveness (BR). To assess the clinical relevance of these experimental changes to chronic asthma, we sought to determine the effect of nasal beclomethasone dipropionate (Bdp) on BR in patients with seasonal allergic rhinitis and asthma. Eighteen subjects with histories of seasonal allergic rhinitis and asthma during the fall pollen season with positive skin tests to short ragweed and bronchial hyperresponsiveness to inhaled methacholine were assigned to receive either nasal Bdp (336 micrograms/day) or placebo for the entire ragweed season. Patients recorded daily nasal and chest symptoms, nasal blockage index, oral peak expiratory flow rates, and supplemental medication use. BR to methacholine was measured during the baseline period and 6 weeks into the ragweed season. Although the Bdp group did have a significant improvement in nasal blockage index, there was no improvement in daily asthma symptom scores, oral peak expiratory flow, or asthma medication use. However, subjects treated with Bdp were protected from the increase in BR seen in the placebo group (geometric mean PC20 placebo group: baseline = 0.70, week 6 = 0.29; Bdp group: baseline = 0.80, week 6 = 0.93; intergroup difference, p = 0.022). We conclude that nasal corticosteroid therapy can prevent the increase in BR associated with seasonal pollen exposure in patients with allergic rhinitis and asthma.

Administration, Intranasal↗
PubMed2006

Mood seasonality: a cross-sectional study of subjects aged between 10 and 25 years.

BACKGROUND: Most of the earlier studies on mood seasonality were conducted in adults and there are few available data on children and adolescents. In two cross sectional surveys, we examined the role of age and gender on seasonal sensitivity in subjects aged 10 to 25 years. METHODS: In survey one, the Seasonal Pattern Assessment Questionnaire for Children and Adolescents (SPAQ-CA) was administered to 1709 subjects (845 females and 864 males) from 10 to 17 years. In survey two, the Seasonal Pattern Assessment Questionnaire (SPAQ) was administered to 1867 subjects (1061 females and 806 males) from 18 to 25 years. RESULTS: Only in survey one was a significant positive correlation found between age and Global Seasonality Score (GSS) (r=.29; p<.00001). Significant gender differences were found at age 14 years and above in survey one, and at all ages in survey two. CONCLUSIONS: The results support the hypothesis that seasonal sensitivity is higher in female subjects.

Adolescent↗