Cytokine concentrations in saliva vs. plasma at rest and in response to intense exercise in adolescent athletes.

BACKGROUND: Salivary measures are advantageous in conducting large paediatric studies involving repeated measures. However, research measuring salivary cytokines in youth is limited. AIM: Compare salivary with plasma concentrations of inflammatory cytokines at rest and following exercise in adolescent swimmers (21 male, 22 female). METHODS: Following collection of resting saliva and blood samples, participants performed a bout of high-intensity interval swimming, with samples taken again ∼15 min post-swimming and analysed for interleukin-6 (IL-6), interleukin 10 (IL-10), and tumour necrosis factor-alpha (TNF-α). RESULTS: Resting IL-10 was significantly lower, while IL-6 and TNF-α were significantly higher in saliva compared with plasma. IL-10 increased from pre- to post-swimming in plasma, but less so in saliva (51% vs. 29%; p = 0.02). TNF-α decreased post-swimming in saliva, but not in plasma (-27% vs -1%; p = 0.01). IL-6 decreased post-swimming in saliva compared with plasma (-21% vs. -3%; p = 0.06). Intraclass correlation coefficients (ICC) revealed no association between salivary and plasma IL-6 and TNF-α, while IL-10 showed a weak correlation only at rest (ICC = 0.39; p = 0.05). CONCLUSIONS: Differences in concentrations and exercise responses, along with weak correlations, suggest that salivary cytokine levels are not an accurate representation of blood cytokine levels, and should not be used as a surrogate measure in paediatric studies.

Capillary facilitation of skeletal muscle function in health and disease.

Skeletal muscle is highly vascularized, with perfusion being tightly regulated to meet wide-ranging metabolic demands. For decades, the capillary supply has been explored mainly in terms of evaluating the capillary numbers and their function in the supply of oxygen and substrates and the removal of metabolic byproducts. This review will focus on recent discoveries concerning the role played by capillaries in facilitating other aspects of cell regulation and maintenance, in health and disease, as well as alterations during the aging process. Novelty Capillaries play a central role in the coordination of the vascular response that controls blood flow during contraction and the cellular responses to which they feed into. Nitric oxide is an important regulatory compound within the cardiovascular system, and a significant contributor to skeletal muscle capillary angiogenesis and vasodilatory response to agonists. The microvascular network between muscle fibres may play a critical role in the distribution of signalling factors necessary for optimal muscle satellite cell function.

The effects of different passive static stretching intensities on recovery from unaccustomed eccentric exercise - a randomized controlled trial.

Effects of passive static stretching intensity on recovery from unaccustomed eccentric exercise of right knee extensors was investigated in 30 recreationally active males randomly allocated into 3 groups: high-intensity (70%-80% maximum perceived stretch), low-intensity (30%-40% maximum perceived stretch), and control. Both stretching groups performed 3 sets of passive static stretching exercises of 60 s each for hamstrings, hip flexors, and quadriceps, over 3 consecutive days, post-unaccustomed eccentric exercise. Muscle function (eccentric and isometric peak torque) and blood biomarkers (creatine kinase and C-reactive protein) were measured before (baseline) and after (24, 48, and 72 h) unaccustomed eccentric exercise. Perceived muscle soreness scores were collected immediately (time 0), and after 24, 48, and 72 h postexercise. Statistical time × condition interactions observed only for eccentric peak torque (p = 0.008). Magnitude-based inference analyses revealed low-intensity stretching had most likely, very likely, or likely beneficial effects on perceived muscle soreness (48-72 h and 0-72 h) and eccentric peak torque (baseline-24 h and baseline-72 h), compared with high-intensity stretching. Compared with control, low-intensity stretching had very likely or likely beneficial effects on perceived muscle soreness (0-24 h and 0-72 h), eccentric peak torque (baseline-48 h and baseline-72 h), and isometric peak torque (baseline-72 h). High-intensity stretching had likely beneficial effects on eccentric peak torque (baseline-48 h), but likely had harmful effects on eccentric peak torque (baseline-24 h) and creatine kinase (baseline-48 h and baseline-72 h), compared with control. Therefore, low-intensity stretching is likely to result in small-to-moderate beneficial effects on perceived muscle soreness and recovery of muscle function post-unaccustomed eccentric exercise, but not markers of muscle damage and inflammation, compared with high-intensity or no stretching.

Acute versus chronic supplementation of sodium citrate on 200 m performance in adolescent swimmers.

BACKGROUND: A double-blinded, placebo-controlled, cross-over design was used to investigate whether two different sodium citrate dihydrate (Na-CIT) supplementation protocols improve 200 m swimming performance in adolescent swimmers. METHODS: Ten, male swimmers (14.9 ± 0.4 years of age; 63.5 ± 4 kg) performed four 200 m time trials with the following treatments: acute (ACU) supplementation (0.5 g kg(-1) administered 120 min pre-trial), acute placebo (PLC-A), chronic (CHR) supplementation (0.1 g∙kg(-1) for three days and 0.3 g kg(-1) on the forth day 120 min pre-trial), and chronic placebo (PLC-C). The order of the trials was randomized, with at least a six-day wash-out period between trials. Blood samples were collected by finger prick pre-ingestion, 100 min post-ingestion, and 3 min post-trial. Performance time, rate of perceived exertion, pH, base excess, bicarbonate and lactate concentration were measured. RESULTS: Post-ingestion bicarbonate and base excess were higher (P < 0.05) in both the ACU and CHR trials compared to placebo showing adequate pre-exercise alkalosis. However, performance time, rate of perceived exertion as well as post-trial pH and lactate concentration were not significantly different between trials. Further analysis revealed that five swimmers, identified as responders, improved their performance time by 1.03% (P < 0.05) and attained higher post-trial lactate concentrations in the ACU versus PLC-A trial (P < 0.05). They also had significantly higher post-trial lactate concentrations compared to the non-responders in the ACU and CHR trials. CONCLUSIONS: Acute supplementation of Na-CIT prior to 200 m swimming performance led to a modest time improvement and higher blood lactate concentrations in only half of the swimmers while the chronic Na-CIT supplementation did not provide any ergogenic effect in this group of adolescent swimmers. TRIAL REGISTRATION: Clinicaltrials.gov NCT01835912.

The effect of a covert manipulation of ambient temperature on heat storage and voluntary exercise intensity.

The modulation of sub-maximal voluntary exercise intensity during heat stress has been suggested as a behavioral response to maintain homeostasis; however, the relationship between thermophysiological cues and the associated response remains unclear. Awareness of an environmental manipulation may influence anticipatory planning before the start of exercise, making it difficult to isolate the dynamic integration of thermophysiological afferents during exercise itself. The purpose of the present study was to examine the direct real-time relationship between thermophysiological afferents and the behavioral response of voluntary exercise intensity. Participants were tasked with cycling at a constant rating of perceived exertion while ambient temperature (T(a)) was covertly changed from 20 °C to 35 °C and then back to 20 °C at 20-minute intervals. Overall, power output (PO) and heat storage, quantified using repeated measures ANOVA, changed significantly over 20-minute intervals (135 ± 39 W, 133 ± 46 W, 120 ± 45 W; 52.35 ± 36.15 W·m(-2), 66.34 ± 22.02 W·m(-2), -66.53 ± 56.01 W·m(-2)). The synchronicity of PO fluctuations with changes in thermophysiological status was quantified using Auto-Regressive Integrated Moving Average (ARIMA) time series analysis. Fluctuations in PO were not synchronized in real time with changes in T(a); heat storage; rectal, skin, or mean body temperature; or sweat rate (stationary-r(2) ≤ 0.10 and Ljung-Box statistic > 0.05 for all variables). We conclude that, while the thermal environment affects physiological responses and voluntary power output while cycling at a constant perceived effort, the behavioral response of voluntary exercise intensity did not depend on a direct response to real-time integration of thermal afferent inputs.

Self-reported compliance to home-based resistance training in cardiac patients.

PURPOSE: To retrospectively identify factors influencing long-term compliance to home-based resistance training (RT) in a cardiac rehabilitation (CR) programme. METHODS: Five hundred and eighteen patients (447 males, 71 females) attending a CR programme consisting of aerobic exercise, education and lifestyle counselling were also offered RT exercises, which they performed over a 72-month period. These patients were sent a questionnaire to examine ongoing participation in RT and perceptions around RT. RESULTS: Sixty-nine percent of the surveys were returned. The mean follow-up time was 38.7+/-25.9 months post-RT prescription (about 2.5 years postgraduation from on-site CR). Among respondents, 50% (50.6% males, 42.9% females) were continuing RT at the time of the survey (compliers), and 50% (49.4% males, 57.1% females) had discontinued RT (dropouts). Compliers perceived greater support for RT participation than dropouts (41.3 and 22.5% perceived strong support, respectively, from family/friends and physicians, P<0.005). Dropouts had a higher percentage of body fat at baseline than compliers (32% of dropouts and 20% of compliers had a body fat >25%, P<0.025). Men participated mainly to 'improve appearance' and women to 'prevent osteoporosis'. Weight reduction was a greater motivator to participate for dropouts than for compliers. The main reason for discontinuing RT was 'lack of motivation'. The most common injuries occurred in one shoulder or the lower back. Only 3% discontinued RT because of injury. CONCLUSION: One-half of patients starting an RT home-based programme were still under training at the time of the survey (mean 38.7 months). A lower percentage of body fat and support from family/friends and physicians seem to increase long-term compliance. There were sex differences in reasons for participation and dropout. Emphasizing achievable benefits that motivate men and women to participate may help to reduce dropout.

Validation of the FAST skating protocol to predict aerobic power in ice hockey players.

Few studies have reported a sport-specific protocol to measure the aerobic power of ice hockey players using a predictive process. The purpose of our study was to validate an ice hockey aerobic field test on players of varying ages, abilities, and levels. The Faught Aerobic Skating Test (FAST) uses an on-ice continuous skating protocol on a course measuring 160 feet (48.8 m) using a CD to pace the skater with a beep signal to cross the starting line at each end of the course. The FAST incorporates the principle of increasing workload at measured time intervals during a continuous skating exercise. Step-wise multiple regression modelling was used to determine the estimate of aerobic power. Participants completed a maximal aerobic power test using a modified Bruce incremental treadmill protocol, as well as the on-ice FAST. Normative data were collected on 406 ice hockey players (291 males, 115 females) ranging in age from 9 to 25 y. A regression to predict maximum aerobic power was developed using body mass (kg), height (m), age (y), and maximum completed lengths of the FAST as the significant predictors of skating aerobic power (adjusted R2 = 0.387, SEE = 7.25 mL.kg-1.min-1, p < 0.0001). These results support the application of the FAST in estimating aerobic power among male and female competitive ice hockey players between the ages of 9 and 25 years.

Effects of concurrent inspiratory and expiratory muscle training on respiratory and exercise performance in competitive swimmers.

The efficiency of the respiratory system presents significant limitations on the body's ability to perform exercise due to the effects of the increased work of breathing, respiratory muscle fatigue, and dyspnoea. Respiratory muscle training is an intervention that may be able to address these limitations, but the impact of respiratory muscle training on exercise performance remains controversial. Therefore, in this study we evaluated the effects of a 12-week (10 sessions week(-1)) concurrent inspiratory and expiratory muscle training (CRMT) program in 34 adolescent competitive swimmers. The CRMT program consisted of 6 weeks during which the experimental group (E, n = 17) performed CRMT and the sham group (S, n = 17) performed sham CRMT, followed by 6 weeks when the E and S groups performed CRMT of differing intensities. CRMT training resulted in a significant improvement in forced inspiratory volume in 1 s (FIV1.0) (P = 0.050) and forced expiratory volume in 1 s (FEV1.0) (P = 0.045) in the E group, which exceeded the S group's results. Significant improvements in pulmonary function, breathing power, and chemoreflex ventilation threshold were observed in both groups, and there was a trend toward an improvement in swimming critical speed after 12 weeks of training (P = 0.08). We concluded that although swim training results in attenuation of the ventilatory response to hypercapnia and in improvements in pulmonary function and sustainable breathing power, supplemental respiratory muscle training has no additional effect except on dynamic pulmonary function variables.

Metabolic characteristics of experimental free vascularized canine gracilis muscle transfers.

A canine gracilis model was used to study muscle energy metabolism and enzyme activities after free vascularized muscle transfer. Fifteen male mongrel dogs underwent orthotopic, free transfer of the left gracilis with microneurovascular anastomosis. After a minimum of 10 months' recovery, muscle biopsy specimens were obtained from the transfers and the contralateral controls and analyzed for relative fiber type areas and maximum activities of phosphorylase, hexokinase, phosphofructokinase, glycerol-3-phosphate dehydrogenase (GPDH), pyruvate kinase, lactate dehydrogenase, citrate synthase, succinate dehydrogenase, 3-hydroxyacyl coenzyme A dehydrogenase (HAD), and creatine phosphokinase. Biopsy specimens obtained before and after a 10 minute, 20-Hz contraction were analyzed for glucose, glycogen, glycolytic intermediates, phosphocreatine, total creatine, and adenine nucleotides (adenosine triphosphate, adenosine diphosphate, adenosine monophosphate, inosine monophosphate, and inosine). There was no significant transfer versus control difference in type I relative fiber area (45 +/- 4 percent versus 44 +/- 3 percent). Total creatine was significantly reduced in the transferred muscles relative to control (83.1 +/- 3.0 mmol/kg versus 100.6 +/- 5.1 mmol/kg dry weight). Maximal activities of phosphorylase, pyruvate kinase, lactate dehydrogenase, citrate synthase, succinate dehydrogenase, HAD, and creatine phosphokinase were diminished in transfers relative to controls, although hexokinase activity was significantly higher in the freely transferred gracilis muscles. During the 20-Hz contraction, muscle transfers produced less force initially, although the force/time integral over the 10-minute stimulation was similar in transfers (277 +/- 25 N/g/second) and controls (272 +/- 24 N/g/second). The contraction was associated with significant glvcogen use and lactate accumulation in both transfers and controls, although this was less pronounced for the transfers. Glycolytic flux appeared muted in the transfers relative to controls. Significant, similar high-energy phosphagen reductions and inosine monophosphate accumulation were noted during the contraction in both groups. Contractile activity is associated with the expected pattern of muscle metabolite changes following free vascularized transfer, indicating the components of cellular energy metabolism are not qualitatively altered after microneurovascular muscle transfer. In contrast, quantitative differences suggest that free vascularized muscle transfer can be associated with a muscle enzyme profile consistent with deconditioning and the presence of denervated muscles fibers in the absence of fiber type profile changes.

Temperature regulation during rest and exercise in the cold in premenarcheal and menarcheal girls.

Temperature regulation during exercise in the cold was examined in 13 adolescent female individuals, aged 13-18 yr. Six girls with established menstrual cycles comprised the eumenorrheic menarcheal (EM) group, and seven nonmenstruating girls comprised the premenarcheal (PM) group. During the first visit, maximal oxygen consumption (Vo(2 max)), height, weight, and percent body fat were measured. The second visit included a determination of metabolic rate in thermoneutrality (21 degrees C), consisting of a 10-min rest period and 20 min of cycling (30% of Vo(2 max)), and a cold test (5 degrees C, 40% humidity, <0.3 m/s air velocity) involving a 20-min rest period and 40 min of cycling (30% of Vo(2 max)). Subjects in the EM group were tested twice in the chamber: once during the follicular and once during the luteal phase. Heat production per kilogram in thermoneutrality and in the cold was significantly (P < 0.05) higher in the PM compared with the EM girls. However, the PM girls had a significantly (P < 0.05) lower core temperature in the cold than the EM group. PM girls also had a significantly higher body surface area-to-mass ratio compared with the EM girls. Although percent body fat between groups was not significantly different, within the PM group percent body fat explained 79% (P < 0.01) of the variance in the decrease of core temperature. There were no menstrual phase-related differences in temperature regulation in either the thermoneutral or cold environment. In conclusion, menstrual phase does not influence temperature regulation in female individuals during adolescence. EM girls had lower metabolic heat production but maintained their core temperature more effectively in the cold than did the PM girls. This thermoregulatory difference between PM and EM girls is mainly a function of geometric differences with maturation-related peripheral vasoconstrictive differences maybe limiting the effectiveness of the mechanism of increased heat storage in younger female individuals.

Habitual physical activity levels and health outcomes of Ontario youth.

Physical activity, sport participation, attitude towards physical education, aerobic fitness, body composition and frequency of upper respiratory tract infections (URTI) were investigated in 256 adolescents [mean age 14.3 (0.3) years] from the Niagara Region Public Schools in Canada. Subjects performed the 20-m shuttle run for prediction of aerobic fitness, and bioelectrical impedance analysis was used to assess relative body fat (%BF). Standardized questionnaires were used to determine physical activity-related variables and frequency of URTI. Males were more active, demonstrated higher shuttle run score, lower %BF and recorded fewer sickness days. In the complete cohort and in males, those who spent less time in sporting activities showed significantly (P<0.05) higher %BF, lower aerobic fitness and higher URTI frequency. Active females differed from hypoactive females only in %BF. Girls also showed significantly (P<0.05) less enjoyment of physical education than boys, which may explain their lack (P<0.05) of participation in sporting activities.

Effect of moderate exercise on salivary immunoglobulin A and infection risk in humans.

The incidence of upper respiratory tract infections (URTI) and salivary immunoglobulin A concentrations [IgA(s)] of nine individuals were examined during 12 weeks of moderate exercise training, and compared to ten sedentary controls. Changes in maximal oxygen uptake were assessed at initial, mid-point and final evaluations (T1-3), while changes in [IgA(s)] and salivary immunoglobulin concentration-salivary albumin concentration ratio ([IgA(s)]:[Alb(s)]) were monitored at T1 and T3. During the 12 week period, symptoms of URTI were self-recorded daily. During the period of training the level of fitness significantly increased ( P<0.05) in the exercise group. The number of days recording symptoms of influenza, but not of cold, and total light URTI symptoms was significantly reduced in the exercise group during the last weeks of training. A significant increase in [IgA(s)] and in [IgA(s)]:[Alb(s)] was found in the exercise group after training. Both [IgA(s)] and [IgA(s)]:[Alb(s)] were significantly related to the number of days showing symptoms of influenza ( P<0.01) and the total number of days of sickness ( P<0.05). These data provide quantitative support for the belief that regular, moderate exercise results in an increased [IgA(s)] at rest and [IgA(s)]:[Alb(s)], which may contribute to a decreased risk of infection.