bluuebunny/crossref_metadata_2025 huggingface dataset:
Two Years of Resistance Training in Older Men and Women: The Effects of Three Years of Detraining on the Retention of Dynamic Strength
Authors: Smith Kelly , Winegard Karen , Hicks Audrey L. , McCartney Neil
Published: June 2009

Dynamic muscle strength (1-RM) and symptom-limited treadmill endurance were compared among three groups (5 M and 5 F per group) of older adults (mean age 72.5 yrs) who had either weight-trained continuously twice per week for 5 years (Tr), ceased to weight train after 2 years (Detr), or acted as controls throughout (Con). The Tr and Detr trained hard (progressing up to 3 sets at up to 80% of 1-RM) for 2 years; the Tr continued training for an additional 3 years at a maintenance level (2 to 3 sets at 60-70% 1-RM), whereas the Detr stopped training for those 3 years. The Con subjects did not train for the duration of the study but took part in identical testing procedures. After 2 years of resistance training, dynamic strength in the Tr and Detr groups increased significantly above baseline and Con values for all exercises, p < 0.0001. Following 3 years of maintenance level training, arm curl, leg press, and bench press 1-RM (sum of both limbs) in the Tr remained significantly above baseline values (21.6 kg = 17%; 15.7 kg = 82%; 8.3 kg = 34%, respectively). The 1-RM in Detr were 18.4 kg (14%), 5.3 kg (24%), and 1.4 kg (9%) above base line for leg press, arm curl, and bench press after 5 years, whereas the Con declined over the 5-yr period by 18.4 kg (-9.7%), 4.4 kg (-19%), and 3.5 kg (-6%), respectively. There were nonsignificant improvements in treadmill performance in the Tr and Detr, and a decline in the Con after 2 years. Treadmill performance declined between Years 2 and 5 in all groups despite continued training (ns). We conclude that: (1) dynamic strength gains from 2 years of resistance training in older individuals are not entirely lost even after 3 years of detraining; (2) these effects may be specific to the exercises performed in the training program; (3) adoption of maintenance-level moderate-intensity training significantly attenuates the decline in dynamic strength of previously trained muscles. Key words: muscle, weightlifting, overload
Human and Rat Skeletal Muscle Adaptations to Spinal Cord Injury
Authors: Gregory Chris M. , Vandenborne Krista , Castro Michael J. , Dudley G. Alton
Published: June 2009

Results of studies of rodent skeletal muscle plasticity are often extrapolated to humans. However, responses to "disuse" may be species specific, in part because of different inherent properties of anatomically similar muscles. Thus, this study quantified human and rat m. vastus lateralis (VL) fiber adaptations to 11 weeks of spinal cord injury (SCI). The m. VL was taken from 8 young (54 d) male Charles River rats after T-9 laminectomy (n = 4) or sham surgery (n = 4). In addition, the m. VL was biopsied in 7 able-bodied and in 7 SCI humans (31.3 ± 4.7 years, mean ± SE). Samples were sectioned and fibers were analyzed for type (I, IIa, IIb/x), cross-sectional area (CSA), succinate dehydrogenase (SDH), α-glycerol-phosphate dehydrogenase (GPDH), and actomyosin adenosine triphosphatase (qATPase) activities. Rat fibers had 1.5- to 2-fold greater SDH and GPDH activities while their fibers were 60% the size of those in humans. The most striking differences, however, were the absence of slow fibers in the rat and its four-fold greater proportion of IIb/x fibers (80% vs. 16% of the CSA) compared to humans. SCI decreased SDH activity more in rats whereas atrophy and IIa to IIb/x fiber shift occurred to a greater extent in humans. It is suggested that the rat is a reasonable model for studying the predominant response to SCI, atrophy. However, its high proportion of IIb/x fibers limits evaluation of the mechanical consequences of shifting to "faster" contractile machinery after SCI. Key words: enzyme, fiber type, disuse, biopsy
Prediction of 200-m Sprint Kayaking Performance
Authors: Someren Ken Van , Palmer Garry S.
Published: June 2009

The aim of this study was to determine the anthropometric and physiological profile of 200-m sprint kayakers and to examine relationships with 200-m race performance. Twenty-six male kayakers who were categorised in two ability groups, international (Int) and national (Nat) level, underwent a battery of anthropometric and physiological tests and a 200-m race. Race time was significantly lower in Int than Nat (39.9 ± 0.8 s and 42.6 ± 0.9 s, respectively). Int demonstrated significantly greater measures of mesomorphy, biepycondylar humeral breadth, circumferences of the upper arm, forearm and chest, peak power and total work in a modified Wingate test, total work in a 2-min ergometry test, peak isokinetic power, and peak isometric force. Significant relationships were found between 200-m time and a number of anthropometric variables and anaerobic and dynamometric parameters. Stepwise multiple regression revealed that total work in the modified Wingate alone predicted 200-m race time (R2 = 0.53, SEE = 1.11 s) for all 26 subjects, while biepycondylar humeral breadth alone predicted race time (R2 = 0.54, SEE = 0.52 s) in Int. These results demonstrate that superior upper body dimensions and anaerobic capacities distinguish international-level kayakers from national-level athletes and may be used to predict 200-m performance. Key words: kayak, laboratory assessment, anthropometry, aerobic, anaerobic
Development of Race Profiles for the Performance of a Simulated 2000-m Rowing Race
Authors: Kennedy Michael D. , Bell Gordon J.
Published: June 2009

The purpose of this study was to determine the race profile for a 2000-m simulated rowing race as well as the effect of training and gender on the race profile. Nineteen men and 19 women undertook a 2000-m simulated rowing race before and after 10 weeks of a typical off-season training program for rowing. Velocity was calculated every 200 m and the deviation in velocities from the mean race velocity (MRV) was plotted every 200 m to produce race profiles for each gender before and after training. The three fastest male rowers varied approximately 0.02 m•s−1 from the MRV after training and displayed a constant-pace model. The fastest female rowers displayed an all-out strategy after training, producing large deviations from MRV. Average squared deviations from the mean (SDM) determined that all groups except the fastest females had a reduction in MRV deviation after training. These results suggest that the optimal race profile for a simulated 2000-m rowing race may be different between genders. Training reduces SDM and influences both male and female pacing patterns such that both exhibit a pacing strategy that is more similar to that of elite athletes in other events of similar and shorter duration. Key words: maximal oxygen consumption, critical power, pacing strategy, critical velocity, accumulated oxygen deficit
Effects of Different Stepwise Reduction Taper Protocols on Cycling Performance
Authors: Neary J. Patrick , Bhambhani Yagesh N. , Mckenzie Donald C.
Published: June 2009

This study examined the effects of different 7-day taper protocols on simulated 20-km time trials (20TT). Following 3 weeks of baseline training, 11 male cyclists ([Formula: see text]= 4.78 ± 0.66 L•min−1) were randomly assigned to one of three stepwise reduction tapers in which training volume was reduced by 30% (T30, n = 5), 50% (T50, n = 6), or 80% (T80, n = 6) of baseline training with intensity (85% [Formula: see text]) maintained. Cardiorespiratory measurements were collected every 5 km during the 20TT. Results revealed a significant (5.4%,p ≤ 0.05) improvement in 20TT performance in the T50 protocol with concomitant increases in [Formula: see text] and O2 pulse. No significant differences were found in T30 or T80. These results showed that a moderate (50%) reduction in weekly training volume appeared to be optimal in terms of enhancing performance. This confirms the contention that proper placement of training volume during tapering, while maintaining exercise intensity, can elicit performance improvements. Key words: tapering, simulated time trial performance, cyclists, physiological mechanisms
Reproducibility of the Cycling Time to Exhaustion at in Highly Trained Cyclists
Authors: Laursen Paul B. , Shing Cecilia M. , Jenkins David G.
Published: June 2009

The purpose of the present study was to examine, in highly trained cyclists, the reproducibility of cycling time to exhaustion (Tmax) at the power output equal to that attained at peak oxygen uptake ([Formula: see text]) during a progressive exercise test. Forty-three highly trained male cyclists (M ± SD; age = 25 + 6 yrs; weight = 75 ± 7 kg; [Formula: see text] = 64.8 ± 5.2 mlùkg−1•min−1) performed two Tmax tests one week apart. While the two measures of Tmax were strongly related (r = 0.884; p < 0.001), Tmax from the second test (245 ± 57 s) was significantly higher than that of the first (237 ± 57 s; p = 0.047; two-tailed). Within-subject variability in the present study was calculated to be 6 ± 6%, which was lower than that previously reported for Tmax in sub-elite runners (25%). The mean Tmax was significantly (p < 0.05) related to both the second ventilatory turnpoint (VT2; r = 0.38) and to [Formula: see text] (r = 0.34). Despite a relatively low within-subject coefficient of variation, these data demonstrate that the second score in a series of two Tmax tests may be significantly greater than the first. Moreover, the present data show that Tmax in highly trained cyclists is moderately related to VT2 and [Formula: see text]Key words: maximal aerobic power, endurance, fatigue, anaerobic threshold, cycling performance
Training Profile Counts for Time-to-Exhaustion Performance
Authors: Basset Fabien A. , Chouinard Richard , Boulay Marcel R.
Published: June 2009

The objective of this study was to compare the time to exhaustion (Tlim) at maximal aerobic speed ([Formula: see text]) in middle- and long-distance runners. Five middle-distance (MDR) and 5 long-distance (LDR) male runners, ages 28 ± 7 years, were tested running on a treadmill, with the Université de Montréal Track Test (UMTT), on maximal velocity and on time-to-exhaustion track tests. During the laboratory test, cardiorespiratory variables (e.g., HR, [Formula: see text]) were assessed. Second, running velocity at [Formula: see text] ([Formula: see text]) during the UMTT was determined and HR values were recorded; also, maximal velocity on a 30-m sprint (V30) and maximal heart rate (HR max) and time to exhaustion were determined on the track. No significant difference was observed between groups during the multistage treadmill test. Significant differences were found between groups for V30and Tlim, with MDR showing a 23% longer running time than LDR. The results of the present study demonstrated that the training profile of middle-distance and long-distance runners plays a significant role in Tlimperformance when [Formula: see text] is obtained during a test with short-duration stages. Key words: maximal oxygen uptake, runners, time limit (Tlim)
Coût énergétique de la course à pied lors de l'enchaînement spécifique d'un duathlon
Authors: Vallier Jean-Marc , Mazure Cyrille , Hausswirth Christophe , Bernard Thierry , Brisswalter Jeanick
Published: June 2009

The aim of the present study was to investigate the variability of the energy cost of running (Cr) during a simulated duathlon performed in outdoor conditions by elite duathletes. This duathlon consisted of 5 km of running, 30 km of cycling, and 5 km of running. The main result was the lack of significant difference in Cr between the two running bouts (210 + 10 mL d'O2 km−1•kg−1 vs. 217 ± 10 mL d'O2 km−1•kg−1). This result is different from those observed during a triathlon, where an increase of energy cost of running bout has been reported. Furthermore, during a short-distance duathlon performed by well-trained subjects, none of the physiological (ventilation alteration, metabolic changes, or dehydration) or biomechanical factors that are classically evoked in triathlon research to explain Cr variability seem to be affected by the run-cycle-run transition. These results seem to minimize the negative effect of the cycle-to-run transition during a short-duration event in well-trained subjects. Key words: duathlon, oxygen uptake, cycle-to-run transition, elite performance
Réponse en catécholamines à l'épreuve de Wingate chez la femme non-entraînée
Authors: Vincent Sophie , Gratas-Delamarche Arlette , Berthon Phanélie Marie , Zouhal Hassane , Jacob Christophe , Bentue-Ferrer Danièle , Delamarche Paul
Published: June 2009

Supramaximal exercises are well known to induce a severe stress on the adrenal medulla and nervous sympathetic system. This stress induces increased plasma catecholamines concentrations. The responses of catecholamines to supramaximal exercises in women are still not well characterized and have been studied mostly in trained subjects. Hence the aim of the present study was to evaluate plasma catecholamine responses to a Wingate test in young and untrained women (n = 6) and men (n = 7). Venous plasma catecholamine concentrations were determined by HPLC, at rest, at the end of the warm-up and of the exercise, and during recovery (5, 10, 20, and 30 mn). Our results failed to show any significant difference in resting catecholamine concentrations ([A]p: 0.41 ± 0.05 vs. 0.45 ± 0.05 nmolúL−1; [NA]p: 3.28 ± 0.68 vs. 2.58 ± 0.26 nmolúL−1), kinetics, and maximal plasma catecholamine concentrations (Amax: 4.47 ± 1.08 vs. 3.31 ± 0.63 nmolúL−1; NAmax: 18.05 ± 1.11 vs. 14.01 ± 2.02 nmolúL−1) in response to the Wingate test between women and men, respectively. The Amax/NAmax ratio used as an index of adrenal medulla sensitivity to sympathetic input was also similar between genders. In conclusion, this study was able to demonstrate, in untrained subjects, that gender did not alter the sympatho-adrenergic response induced by a severe stress. Key words: stress hormones, gender, luteal phase
Fitness as a Determinant of the Oxygen Uptake/Work Rate Slope in Healthy Children and Children With Inflammatory Myopathy
Authors: Drinkard Bart E. , Hicks Jeanne , Danoff Jerome , Rider Lisa G.
Published: June 2009

There is evidence that the slope of the change in oxygen uptake accompanying changes in work rate ([Formula: see text]) during moderate incremental exercise is influenced by fitness (peak[Formula: see text]). We set out to determine whether [Formula: see text] was related to fitness in a group of healthy children and in children with juvenile dermatomyositis (JDM), a condition associated with decreased peak [Formula: see text]. We also hypothesized that [Formula: see text] would be significantly decreased in children with JDM compared to healthy children. Methods: Twelve children (2 boys) with JDM, mean age 11.6 ± 3.6 yrs, and 20 healthy children (4 boys), mean age 11.3 ± 2.9 years, performed an incremental exercise test using a cycle ergometer. [Formula: see text] below the anaerobic threshold was analyzed using linear regression. Correlations between peak [Formula: see text] and [Formula: see text] were calculated, and differences between the JDM and healthy groups were analyzed using independent t-tests. Results: The [Formula: see text] was significantly correlated with peak[Formula: see text] for children with JDM (r = 0.71,p < 0.01), healthy children (r = 0.53, p < 0.01), and all children combined (r = 0.78, p < 0.001). The [Formula: see text] (7.4 ± 1.4 vs. 10.8 ± 1.2 ml O•min−1•wat−1) and peak oxygen uptake ([Formula: see text]) (19.2 ± 5.0 vs. 31.4 ± 7.2 ml O2•kg−1•min−1) were significantly lower in children with JDM than in healthy children, respectively (all p ≤ 0.001). Conclusion: Fitness is significantly related to [Formula: see text] in healthy children and those with JDM. Children with JDM have a significantly lower [Formula: see text] than healthy children. Further study is needed to identify specific factors influencing [Formula: see text]. Key words: exercise efficiency, juvenile dermatomyositis, peak [Formula: see text]
Physiological Hypertrophy of the FHL Muscle Following 8 Weeks of Progressive Resistance Exercise in the Rat
Authors: Hornberger Jr. Troy A. , Farrar Roger P.
Published: June 2009

In humans, progressive resistance exercise is recognized for its ability to induce skeletal muscle hypertrophy. In an attempt to develop an animal model which mimics human progressive resistance exercise, Sprague-Dawley rats were trained to climb a 1.1-m vertical (80° incline) ladder with weights secured to their tail. The rats were trained once every 3 days for 8 weeks. Each training session consisted of 4-9 (6.02 ± 0.23) climbs requiring 8-12 dynamic movements per climb. Based on performance, the weight carried during each session was progressively increased. Over the course of 8 weeks, the maximal amount of weight the rats could carry increased 287%, p ≤ 0.001. The improved training performance was associated with a 23% absolute increase in the weight of the flexor hallucis longus (FHL), with a concomitant 24% increase in both total and myofibrillar protein, p ≤ 0.001. Peak tetanic tension (Po) of the FHL increased 20%, p ≤ 0.001, while specific tetanic tension (SPo) was not altered. No change in twitch tension (Pt) was observed, which resulted in a 22% decrease in specific twitch tension (SPt) p ≤ 0.01. Despite a decrease in resistance to fatigue, p ≤ 0.05, myosin heavy chain composition, ATP, ADP, creatine, and creatine phosphate concentrations of the FHL were not altered. The results of this study describe an animal model that mimics many of the training parameters and physiological adaptations observed with human progressive resistance exercise. Key words: contractile properties, high-energy phosphates, myosin heavy chain, fatigue resistance
The Economic Costs Associated With Physical Inactivity and Obesity in Canada: An Update
Authors: Katzmarzyk Peter T. , Janssen Ian
Published: June 2009

The purpose of this analytical review was to estimate the direct and indirect economic costs of physical inactivity and obesity in Canada in 2001. The relative risks of diseases associated with physical inactivity and obesity were determined from a meta-analysis of existing prospective studies and applied to the health care costs of these diseases in Canada. Estimates were derived for both the direct health care expenditures and the indirect costs, which included the value of economic output lost because of illness, injury-related work disability, or premature death. The economic burden of physical inactivity was $5.3 billion ($1.6 billion in direct costs and $3.7 billion in indirect costs) while the cost associated with obesity was $4.3 billion ($1.6 billion of direct costs and $2.7 billion of indirect costs). The total economic costs of physical inactivity and obesity represented 2.6% and 2.2%, respectively, of the total health care costs in Canada. The results underscore the importance of public health efforts aimed at combating the current epidemics of physical inactivity and obesity in Canada. Key words: overweight, lifestyle, meta analysis, population attributable risk, cost-of-illness
Intensive Swimming Exercise-Induced Oxidative Stress and Reproductive Dysfunction in Male Wistar Rats: Protective Role of α-Tocopherol Succinate
Authors: Manna Indranil , Jana Kuladip , Samanta Prabhat Kumar
Published: June 2009

In the present study, 30 male rats (age 3 mos, Wt 128.6 ± 3.7 g) were randomly divided into Control group (CG), Experimental group (EG), and Supplemented group (SG), 10 per group. An exercise protocol (3 hrs swimming per day, 5 days a week for 4 weeks) was followed in EG and SG, with no exercise in CG. In SG, α-tocopherol succinate was injected subcutaneouly at a dose of 50 mg•kg−1per body weight per day. After 4 weeks of exercise, significant diminutions (p <  0.05) were noted in somatic indices of testes and accessory sex organs; seminiferous tubuler diameter (STD); testicular Δ5, 3β-hydroxysteroid dehydrogenase (Δ5, 3β-HSD) 17 β-hydroxysteroid dehydrogenase (17 β-HSD) activities; plasma levels of testosterone (T), luteinizing hormone (LH); preleptotine spermatocytes (pLSc), mid-pachytene spermatocytes (mPSc), and Stage 7 spermatids (7 Sd); testicular α-tocopherol and glutathione (GSH) content; superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), and glutathione-s-transferase (GST) activities in EG when compared to CG. Moreover, a significant elevation (p <  0.05) in malondialdehyde (MDA) was found in testes of EG compared to CG. No significant alteration was noted in body weight among the groups. Co-administration of α-tocopherol succinate restored the above parameters. Intensive swimming exercise-induced oxidative stress causes dysfunction in the male reproductive system, which can be protected by α-tocopherol succinate. Key words: spermatogenesis, steroidogenesis, lipid peroxidation, vitamin E
Effects of Recovery Mode on Performance, O2 Uptake, and O2 Deficit During High-Intensity Intermittent Exercise
Authors: Dorado Cecilia , Sanchis-Moysi Joaquin , Calbet José A. L.
Published: June 2009

The aim of this study was to determine the influence of activity performed during the recovery period on the aerobic and anaerobic energy yield, as well as on performance, during high-intensity intermittent exercise (HIT). Ten physical education students participated in the study. First they underwent an incremental exercise test to assess their maximal power output (Wmax) and [Formula: see text]On subsequent days they performed three different HITs. Each HIT consisted of four cycling bouts until exhaustion at 110% Wmax. Recovery periods of 5 min were allowed between bouts. HITs differed in the kind of activity performed during the recovery periods: pedaling at 20% [Formula: see text] (HITA), stretching exercises, or lying supine. Performance was 3-4% and aerobic energy yield was 6-8% (both p < 0.05) higher during the HITA than during the other two kinds of HIT. The greater contribution of aerobic metabolism to the energy yield during the high-intensity exercise bouts with active recovery was due to faster [Formula: see text] kinetics (p < 0.01) and a higher [Formula: see text]during the exercise bouts preceded by active recovery (p < 0.05). In contrast, the anaerobic energy yield (oxygen deficit and peak blood lactate concentrations) was similar in all HITs. Therefore, this study shows that active recovery facilitates performance by increasing aerobic contribution to the whole energy yield turnover during high-intensity intermittent exercise. Key words: fatigue, oxygen deficit, anaerobic capacity, lactate
The Sarcoplasmic Reticulum in Muscle Fatigue and Disease: Role of the Sarco(endo)plasmic Reticulum Ca2+-ATPase
Authors: Tupling A. Russell
Published: June 2009

Skeletal muscles induced to contract repeatedly respond with a progressive loss in their ability to generate a target force or power. This condition is known simply as fatigue. Commonly, fatigue may persist for prolonged periods of time, particularly at low activation frequencies, which is called low-frequency fatigue. Failure to activate the contractile apparatus with the appropriate intracellular free calcium ([Ca2+]f) signal contributes to fatigue but the precise mechanisms involved are unknown. The sarcoplasmic reticulum (SR) is the major organelle in muscle that is responsible for the regulation of [Ca2+]f, and numerous studies have shown that SR function, both Ca2+release and Ca2+uptake, is impaired following fatiguing contractile activity. The major aim of this review is to provide insight into the various cellular mechanisms underlying the alterations in SR Ca2+cycling and cytosolic [Ca2+]fthat are associated both with the development of fatigue during repeated muscle contraction and with low-frequency or long-lasting fatigue. The primary focus will be on the role of the sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) in normal muscle function, fatigue, and disease. Key words: calcium release, calcium uptake, muscle relaxation, low-frequency fatigue, Brody disease
Monitoring Individual Erector Spinae Fatigue Responses Using Electromyography and Near Infrared Spectroscopy
Authors: Albert Wayne J. , Sleivert Gordon G. , Neary J. Patrick , Bhambhani Yagesh N.
Published: June 2009

This study examined the utility of electromyography and near-infrared spectroscopy (NIRS) in assessing m. erector spinae activity during the Biering-Sørensen Back Muscle Endurance (BSME) test. Six men and four women (27.0 ± 7.1 years of age) performed the BSME test (time = 131.5 ± 43.5 s). EMG was used to quantify neuromuscular activity of the right and left side at the L3 level, and root mean square was scaled for maximum value at the start of the exercise. NIRS was used to evaluate blood volume (BV) and oxygenation (OX) simultaneous with EMG bilaterally at the L3 level. There was a decrease to 49 ± 8% of initial median frequency (mean = 83 Hz) on both right and left sides when the exercise was 90% complete, and the slope of the median frequency/time relationship was significantly related to BSME time (r = 0.82). Group means for BV increased during back exercise while OX decreased and was significantly different between right and left sides of the lower back. However, large OX response differences among individuals and between right and left sides were noted. OX and median frequency were moderately related (r = 0.27-0.38). It appears that NIRS combined with EMG is a promising tool for assessing localized metabolic and neuromuscular activity during static contractions of the lower back. Key words: back endurance, back health, muscle oxygenation, blood volume
The Effects of a Moderate Physical Activity Program on Thermoregulatory Responses in a Warm Environment in Men
Authors: Shields Casie L. , Giesbrecht Gordon G. , Pierce Grant N. , Ready A. Elizabeth
Published: June 2009

Moderate intensity training induces health benefits, but its influence on thermoregulatory responses during exercise in a warm environment is unclear. Twelve inactive men (mean age 24.0 ± 6.5 yrs) underwent exercise heat tests, and peak [Formula: see text] before and after a moderate training program (n = 8) or no training intervention (n = 4). Assignment to groups was random. All subjects were initially below the guidelines for physical activity set forth by Health Canada, the Canadian Society for Exercise Physiology (CSEP), and the U.S. Surgeon General. Those in the 12-week training program participated in activities such as cycling, walking, and recreational sports. Subjects were instructed to train at 50% [Formula: see text] reserve, and to gradually increase energy expenditure beyond the above mentioned recommendations. In the training group, peak [Formula: see text] increased 13%, p < 0.01, and resting peripheral blood flow during heat stress increased, p < 0.01, indicating some initial thermoregulatory benefits. No significant differences were observed in esophageal temperature or sweating threshold. Health benefits associated with thermoregulatory adaptations to exercise in a warm environment may require more vigorous exercise than recommended by current physical activity guidelines. Key words: core temperature, energy expenditure, health benefits, moderate intensity, thermoregulation
Perspective: Sedentary Death Syndrome- Where to From Here?
Authors: Katzmarzyk Peter T.
Published: June 2009

not available
Application of Near Infrared Spectroscopy to Exercise Sports Science
Authors: Neary J. Patrick
Published: June 2009

Over the past 15 years the use of near infrared spectroscopy in exercise and sports science has increased exponentially. The majority of these studies have used this noninvasive technique to provide information related to tissue metabolism during acute exercise. This has been undertaken to determine its utility as a suitable tool to provide new insights into the heterogeneity and regulation of local tissue metabolism, both in cerebral and skeletal muscle tissue. In the accompanying articles in this symposium, issues related to the principles, techniques, limitations (Ferrari et al., 2004), and reliability and validity of NIRS in both cerebral and skeletal muscle tissue (Bhambhani, 2004), mostly during acute exercise, have been addressed and will not be discussed here. Instead, the present paper will focus specifically on the application of NIRS to exercise sports science, with an emphasis on how this technology has been applied to exercise training and sport, and how it can be used to design training programs for athletes. Key words: tissue de-oxygenation, hemoglobin volume, endurance training, resistance exercise, taper, applied physiology
Muscle Oxygenation Trends During Dynamic Exercise Measured by Near Infrared Spectroscopy
Authors: Bhambhani Yagesh N.
Published: June 2009

During the last decade, NIRS has been used extensively to evaluate the changes in muscle oxygenation and blood volume during a variety of exercise modes. The important findings from this research are as follows: (a) There is a strong correlation between the lactate (ventilatory) threshold during incremental cycle exercise and the exaggerated reduction in muscle oxygenation measured by NIRS. (b) The delay in steady-state oxygen uptake during constant work rate exercise at intensities above the lactate/ventilatory threshold is closely related to changes in muscle oxygenation measured by NIRS. (c) The degree of muscle deoxygenation at the same absolute oxygen uptake is significantly lower in older persons compared younger persons; however, these changes are negated when muscle oxygenation is expressed relative to maximal oxygen uptake values. (d) There is no significant difference between the rate of biceps brachii and vastus lateralis deoxygenation during arm cranking and leg cycling exercise, respectively, in males and females. (e) Muscle deoxygenation trends recorded during short duration, high-intensity exercise such as the Wingate test indicate that there is a substantial degree of aerobic metabolism during such exercise. Recent studies that have used NIRS at multiple sites, such as brain and muscle tissue, provide useful information pertaining to the regional changes in oxygen availability in these tissues during dynamic exercise. Key words: blood volume, noninvasive measurement
Ventilatory Threshold Characterizations During Incremental Rowing and Cycling Exercises in Older Subjects
Authors: Deruelle Fabien , Grosbois Jean-Marie , Mucci Patrick , Bart Frédéric , Lensel Ghislaine , Fabre Claudine
Published: June 2009

In order to individualize the intensity of an aerobic training program on different ergometers in healthy elderly subjects using a single test of muscular exercise, we analysed cardiorespiratory responses in 8 men (65.7 ± 4.5 yrs) and 10 women (63.3 ± 4.8 yrs). The heart rate corresponding to the ventilatory threshold was defined as individualised exercise intensity. All subjects carried out two incremental exercise tests on the cycle and rowing ergometers. For men, the results on the cycle ergometer and rowing ergometer demonstrated that, at ventilatory threshold, heart rates were not significantly different (114.6 ± 13.7 and 115.6 ± 14.2 beats min−1, respectively), but ventilation was significantly higher in rowing (p <  0.05). At ventilatory threshold, heart rates for women were not significantly different between the cycle ergometer and rowing ergometer (121.3 ± 12.4 and 125.1 ± 15.2 beats min−1, respectively), but ventilation was significantly higher in rowing (p <  0.01). At maximal exercise, maximal tidal volume for men (p <  0.01) and women (p <  0.05) was significantly higher in rowing. In spite of alterations of breathing patterns on the rowing ergometer, it is possible to design an individualized training program for healthy elderly subjects based on a single muscle evaluation exercise in order to diversify and optimize the cardiorespiratory benefits following an aerobic training program. Key words: aging, gas exchange, exercise testing, breathing pattern
Effect of Exercise Timing on Postprandial Lipemia in Hypertriglyceridemic Men
Authors: Zhang John Q. , Ji Lisa L. , Nunez Guadalupe , Feathers Scott , Hart Curtis L. , Yao Wan Xiang
Published: June 2009

We investigated the effect of exercise timing on attenuation of postprandial hyper-triglyceridemia (PHTG) in individuals with hypertriglyceridemia (HTG). Subjects were 10 males (TG = 290.1 ± 28.5 mg/dl). Each subject performed a control trial (Ctr), 12-hr premeal exercise trial (12-hr Pre), and 24-hr premeal exercise trial (24-hr Pre). In each trial, subjects had a fat-rich meal. In the exercise trials they jogged on a treadmill at 60% of their [Formula: see text] for 1 hr at a designated time. Blood samples were taken at 0 (immediately before the fat meal), and at 2, 4, 6, 8, and 24 hrs after the meal. The results indicated that plasma TG concentrations in 12-hr Pre were lower than in Ctr and 24-hr Pre (p <  0.03). The area score under the TG concentration curve (TG AUC score) in 12-hr Pre was 37% and 33% lower than in 24-hr Pre and Ctr (p <  0.02), respectively. Insulin concentrations in 12-hr Pre were lower than Ctr and 24-hr Pre (p <  0.001). The plasma nonesterified fatty acid (NEFA) concentration was higher in 12-hr Pre than in both 24-hr Pre and Ctr (p <  0.003). There were no trial differences in both HDLtot-Ch and HDL2-Ch. These results suggest that exercising 12 hrs prior to a fat-meal intake significantly reduces PHTG response whereas exercising 24 hrs prior to the meal does not attenuate PHTG in hypertriglyceridemic men. The effect of an acute exercise bout on PHTG lowering may be short-lived and diminished by 24 hrs. Key words: high-density lipoprotein cholesterol, triglyceride, lipoprotein lipase, insulin
The Importance of Glutamate in Skeletal Muscle Metabolism Under Differrent Exercise Conditions
Authors: Mourtzakis Marina
Published: June 2009

not available
Effects of Acute Ingestion of Sodium Citrate on Metabolism and 5-km Running Performance: A Field Study
Authors: Ööpik Vahur , Saaremets Ivi , Timpmann Saima , Medijainen Luule , Karelson Kalle
Published: June 2009

The purpose of the study was to (a) assess the effects of sodium citrate ingestion on metabolism and performance capacity in a 5-km competitive outdoor stadium run in trained male runners, and (b) elucidate the potential relationship between citrate-induced changes in plasma volume, body mass, and performance. Ten subjects (age 22.1 ± 2.5 yrs, body mass 74.1 ± 6.1 kg, height 180.1 ± 5.7 cm, [Formula: see text] 60.8 ± 5.5 ml kg−1•min−1) participated in the study. There was no effect of treatment on 5-km running time: 1100.0 ± 79.1 and 1082.7 ± 62.0 s in citrate (CIT) and in placebo (PLC) trials, respectively, p = 0.09. Blood pH increased from 7.34 ± 0.07 to 7.49 ± 0.07 (p = 0.002) as a result of administering sodium citrate in the amount of 0.5 g•kg−1 body mass in 1.5 litres of solution but remained stable while the equal volume of placebo drink was consumed: 7.40 ± 0.04 and 7.44 ± 0.09. The relative change in plasma volume after administering the drink was -1.99 ± 3.49% in the PLC and 9.75 ± 6.51% in the CIT trial (p = 0.001). Body mass did not differ before drinking; however, before the start the subjects were heavier in the CIT trial (74.2 ± 6.1 kg) vs. the PLC trial (73.4 ± 6.2 kg, p = 0.048). The shifts in plasma volume and body mass were not related to changes in performance. The results suggest that ingestion of sodium citrate induces an increase in water retention, plasma volume, and blood pH before exercise but does not improve performance in a 5-km competitive run infield conditions in trained male runners. Key words: buffering solution, endurance performance, plasma volume, body mass
and EMG Activity Kinetics During Moderate and Severe Constant Work Rate Exercise in Trained Cyclists
Authors: Cleuziou Christophe , Perrey Stéphane , Borrani Fabio , Lecoq Anne Marie , Courteix Daniel , Germain Philippe , Obert Philippe
Published: June 2009

The purpose of this study was to compare O2 uptake [Formula: see text] and muscle electromyography activity kinetics during moderate and severe exercise to test the hypothesis of progressive recruitment of fast-twitch fibers in the explanation of the [Formula: see text] slow component. After an incremental test to exhaustion, 7 trained cyclists (mean ± SD, 61.4 ± 4.2 ml•min−1•kg−1) performed several square-wave transitions for 6 min at moderate and severe intensities on a bicycle ergometer. The [Formula: see text] response and the electrical activity (i.e., median power frequency, MDF) of the quadriceps vastus lateralis and vastus medialis of both lower limbs were measured continuously during exercise. After ∼2 to 3 min of exercise onset, MDF values increased similarly during moderate and severe exercise for almost all muscles whereas a [Formula: see text] slow component occurred during severe exercise. There was no relationship between the increase of MDF values and the magnitude of the [Formula: see text] slow component during the severe exercise. These results suggest that the origin of the slow component may not be due to the progressive recruitment of fast-twitch fibers. Key words: median power frequency, O2 uptake, recruitment of fast-twitch fibers, [Formula: see text]slow component
Homocysteine and Cardiovascular Disease: Interactions Between Nutrition, Genetics and Lifestyle
Authors: Brosnan John T.
Published: June 2009

Homocysteine is a sulfur-containing amino acid that arises during methionine metabolism. Although its concentration in plasma is only about 10 micromolar, even moderate hyperhomocysteinemia is associated with increased incidence of cardiovascular disease and Alzheimer's disease. Elevations in plasma homocysteine are commonly found as a result of vitamin deficiencies, polymorphisms of enzymes of methionine metabolism, and renal disease. Pyridoxal, folic acid, riboflavin, and Vitamin B12 are all required for methionine metabolism, and deficiences of each of these vitamins result in elevated plasma homocysteine. A polymorphism of methylenetetrahydrofolate reductase (C677T), which is quite common in most populations with a homozygosity rate of 10-15%, is associated with moderate hyperhomocysteinemia, especially in the context of marginal folate intake. Plasma homocysteine is inversely related to plasma creatinine in patients with renal disease. This is due to an impairment in homocysteine removal in renal disease. The role of these factors, and of modifiable life style factors, in affecting methionone metabolism and in determining plasma homocysteine levels is discussed. Key words: methionine, liver metabolism, folic acid, vitamin B12, polymorphisms, neural tube defects, end-stage renal disease, coffee consumption
Effects of Long-Term Tennis Playing on the Muscle-Bone Relationship in the Dominant and Nondominant Forearms
Authors: Ducher Gaële , Jaffré Christelle , Arlettaz Alexandre , Benhamou Claude-Laurent , Courteix Daniel
Published: June 2009

The relationship between muscle strength and bone mineral density illustrates the positive effect of mechanical loading on bone. But local and systemic factors may affect both muscle and bone tissues. This study investigated the effects of long-term tennis playing on the relationship between lean tissue mass and bone mineral content in the forearms, taking the body dimensions into account. Fifty-two tennis players (age 24.2 ± 5.8 yrs, 16.2 ± 6.1 yrs of practice) were recruited. Lean tissue mass (LTM), bone area, bone mineral content (BMC), and bone mineral density were measured at the forearms from a DXA whole-body scan. Grip strength was assessed with a dynamometer. A marked side-to-side difference (p <  0.0001) was found in favor of the dominant forearm in all parameters. Bone area and BMC correlated with grip strength on both sides (r = 0.81-0.84, p <  0.0001). The correlations were still significant after adjusting for whole-body BMC, body height, or forearm length. This result reinforced the putative role of the muscles in the mechanical loading on bones. In addition, forearm BMC adjusted to LTM or grip strength was higher on the dominant side, suggesting that tennis playing exerts a direct effect on bone. Key words: bone mineral content, muscle strength, unilateral loading, mechanical stress, absorptiometry
Association Between the ACE I/D) Gene Polymorphism and Physical Performance in a Homogeneous Non-Elite Cohort
Authors: Cam F. Sirri , Colakoglu Muzaffer , Sekuri Cevad , Colakoglu Sule , Sahan Çagatay , Berdeli Afig
Published: June 2009

Background: I/D polymorphism of the ACE gene may be associated with better endurance performance and a stronger response to exercise training. The aim of this study was to investigate the association between ACE gene polymorphism and athletic performance in a homogeneous cohort. Methods: Eighty-eight male non-elite Caucasian Turkish athletes with similar training backgrounds for at least for 6 months were studied for ACE gene polymorphisms by PCR analysis. Performance on the 60-meter sprint and middle-distance running tests were evaluated. Results: The distributions of the ACE I/D genotypes were 20.5%, 40.9%, and 38.6% for II, ID, and DD polymorphisms in the whole group (N = 88), respectively. The ACE DD genotype frequency was significantly higher in the superior group (56.7%) than in the poor (37.9%) and mediocre (20.7%) group in middle-distance running performance (χ2 = 11.778; p = 0.019). Conclusion: The ACE DD genotype may be related to better short-duration aerobic endurance performance. Larger homogeneous cohorts may help clarify the association between ACE I/D polymorphism and physical performance. Key words: genetics, endurance performance, DNA, sprint
The Postexercise Increase in the Threshold for Cutaneous Vasodilation and Sweating is Not Observed With Extended Recovery
Authors: Kenny Glen P. , Journeay W. Shane
Published: June 2009

The following study was conducted to evaluate the hypothesis that an increase in the postexercise onset threshold for cutaneous vasodilation (ThVD) and sweating (ThSW) would not be observed upon the restoration of baseline mean arterial pressure (MAP). Subjects remained either seated resting for 15 min or performed 15 min of treadmill running at 70% [Formula: see text]peak followed by either 20- (short) or 60-min (extended) recovery. At the end of each recovery protocol (20 and 60 min) a water perfusion suit was then used to increase mean skin temperature until ThVD and ThSW was noted. Exercise resulted in an increase in ThVD and ThSW of 0.24 ± 0.03 and 0.24 ± 0.02 °C, respectively, above no-exercise for the short recovery (p < 0.05). No increase was measured for the extended recovery. Postexercise MAP was significantly reduced prior to whole-body warming for the short recovery whereas no reduction was measured for the extended recovery. The increase in ThVD and ThSW, measured during the early stages of recovery, is reversed with the reestablishment of baseline MAP. Key words: postexercise hypotension, exercise recovery, baroreceptors, heat stress
Physical Fitness and the Metabolic Syndrome in Adults From the Quebec Family Study
Authors: Boulé Normand G. , Bouchard Claude , Tremblay Angelo
Published: June 2009

Physically fit individuals have a lower risk of cardiovascular disease and type 2 diabetes. However, it is unknown whether the associations between physical fitness and the metabolic syndrome are independent of total and abdominal adiposity. Physical fitness was defined as the physical work capacity on a cycle ergometer at heart rate of 150 bpm (PWC 150) in a sample of 158 men and 198 women 20-60 years of age. PWC 150 was adjusted for fat-free mass prior to the analyses. Percent body fat was estimated by hydrostatic weighing. Visceral and subcutaneous abdominal fat were measured by computed tomography. The prevalence of the metabolic syndrome was based on two definitions. The metabolic syndrome decreased with increasing fitness in men (approx. 6 times higher in less fit vs. most fit fertile, p <  0.05) and in women (approx. 4 times higher in less fit vs. most fit tertile, p <  0.05). Fitness was negatively associated with most individual components of the metabolic syndrome, except HDL-cholesterol for which the correlation was positive. However, in men and in women, the effects of physical fitness on the individual components of the metabolic syndrome were attenuated after considering total and abdominal adiposity. Key words: aerobic capacity, adiposity, abdominal fat, insulin resistance syndrome
Regulatory Impact of Intra-Hepatic Carbohydrate and Lipid Metabolism
Authors: Lavoie Jean-Marc , Bergeron Raynald , Latour Martin G.
Published: June 2009

The first evidence that the liver can afferently contribute to regulatory activities comes from studies on regulation of food intake. The hepatic afferent pathway has been shown to be responsive to glucoprivic as well as lipoprivic stimuli. Similarly to regulation of food intake, it has been reported that the liver may afferently contribute to the metabolic regulation of exercise. The best reported evidence of this view is the observation that the decrease in insulin and the increase in glucagon and noradrenaline levels during exercise are diminished in hepatic vagotomized rats (Lavoie et al., 1989). The concept behind these observations is that the liver, through the existence of hepatic glucoreceptors, is responsive to a decrease in glycogen content or to some metabolites of the glycolytic chain related to liver glycogen content. There is also some evidence that lipids in the liver may have some regulatory impact inside and outside the liver. Recent interest in looking at lipid metabolism in liver has been spurred by the observation that the increased flux of lipids through the hepatic portal vein has been associated with increased risks of metabolic and cardiovascular abnormalities. To explore this avenue, a 10% triglyceride emulsion was infused into either the portal or a peripheral vein of rats for 48 hrs while another group of rats was acutely infused for 2 hrs into the portal vein. The results indicate that all of these lipid infusions resulted in an increase in liver lipid infiltration, which may be associated with the development of a state of hepatic and peripheral insulin resistance. Key words: hepatic afferents, insulin, portal vein infusion, fatty liver
Insulin Sensitivity in Skeletal Muscle Regulated by a Hepatic Hormone, HISS
Authors: Lautt W. Wayne
Published: June 2009

The current state of the HISS (hepatic insulin sensitizing substance) hypothesis is briefly outlined. In the postmeal absorptive state, 50-60% of the glucose storage action of insulin is accounted for by the actions of HISS released from the liver and acting on skeletal muscle. Hepatic parasympathetic nerves permissively regulate the ability of a pulse of insulin to release HISS, thereby potentiating the impact of insulin in the fed state. HISS release in response to insulin decreases progressively with fasting to create a physiological state of HISS-dependent insulin resistance. HISS release is regulated by parasympathetic nerves via muscarinic receptors and nitric oxide, and insulin resistance of skeletal muscle produced by hepatic denervation is reversed by intraportal but not intravenous acetylcholine or a nitric oxide donor. It is suggested that HISS-dependent insulin resistance occurs in animal models including sucrose-fed rats, spontaneously hypertensive rats, chronic liver disease, fetal alcohol effect in the adult offspring, and type 2 diabetes. Key words: insulin resistance, RIST, parasympathetic nerves, liver, diabetes