Description

The Canadian Journal of Applied Physiology (CJAP) focuses on both basic and applied research articles that examine the relationship between the biological sciences and physical activity, fitness, and health. The journal provides exercise physiologists, fitness researchers, and health care professionals as well as other basic and applied physiological scientists, with in-depth coverage of applied physiology. The journal offers reviews, basic scientific studies, and other applied physiology information.

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Human Kinetics

Publications in this journal

• Effects of mild leg exercise in a seated position on haemostatic parameters under normobaric hypoxic conditions.

  Authors: Thorsten Schiffer, Heiko K Strüder, Hans-Georg Predel, Wildor Hollmann

  Canadian journal of applied physiology = Revue canadienne de physiologie appliquée. 30(6):708-22.

  This study tested the hypothesis that in humans mild leg exercise affects haemostasis in normobaric hypoxia and thus avoids the development of a deep venous thrombosis (DVT). Eight young men breathedThis study tested the hypothesis that in humans mild leg exercise affects haemostasis in normobaric hypoxia and thus avoids the development of a deep venous thrombosis (DVT). Eight young men breathed in a 15.4% oxygen in nitrogen gas mixture for 2 hrs while seated at rest (R) or seated and performing a 3-min mild leg exercise program (Ex) at 15-min intervals to assess the impact of mild leg exercise on haemostatic parameters related to the risk of developing DVT, as has been discussed for hypobaric hypoxic conditions during commercial airline travel. Capillary blood gases were analysed every 30 min. Heart rate was monitored continuously. Haemostatic parameters were analysed from venous blood at the beginning, after 1 and 2 hrs, and after a 30-min resting period in normoxic conditions. Plasminogen-activator-inhibitor-1 diminished in both tests in hypoxia, but not after the resting period. Antithrombin-III decreased in R in the hypoxic period. Platelet count, international normalized ratio, partial thromboplastin time remained unchanged, as did highly sensitive parameters like tissue-plasminogen-activator, alpha2-antiplasmin, d-dimers, thrombin-antithrombin-III-complexes, and prothrombin-fragments 1 and 2. The haematocrit decreased significantly in R. The mild leg execise prevented the decrease of antithrombin-III and caused an increase in haematocrit after an initial drop in the first hour. The present study revealed that normobaric hypoxia did not have clinically relevant effects on haemostasis in humans. Mild leg exercise carried out under those conditions did not lead, via alterations in haemostasis, to a reduced risk of DVT.

• Pedometer-determined step count guidelines for classifying walking intensity in a young ostensibly healthy population.

  Authors: Catrine Tudor-Locke, Susan B Sisson, Tracy Collova, Sarah M Lee, Pamela D Swan

  Canadian journal of applied physiology = Revue canadienne de physiologie appliquée. 30(6):666-76.

  PURPOSE: (a) To establish pedometer steps/min intensity categories (i.e., light, moderate, hard, very hard) for adults under controlled conditions, and (b) use these cut-points to ascertain thePURPOSE: (a) To establish pedometer steps/min intensity categories (i.e., light, moderate, hard, very hard) for adults under controlled conditions, and (b) use these cut-points to ascertain the number of steps expected in 30 minutes of moderate intensity activity. METHODS: 25 men and 25 women, ages 18-39 years, performed 6-min exercise bouts at 3 treadmill speeds (4.8, 6.4, and 9.7 km/hr). Yamax SW-200 pedometers indicated steps, and steady-state VO2 was recorded. METs were calculated by dividing steady-state VO2 by 3.5 ml x kg(-1) x min(-1). Linear regression was used to quantify the relationships between steps/min and METs across all speeds. Ten participants (5 M, 5 F) were randomly selected from the original 50 and constituted a holdout sample for cross-validation purposes (i.e, comparing actual and predicted METs; paired t-test). RESULTS: The regression equation for males was: METs = -7.065 + (0.105 x steps/min) r2 = 0.803. For females it was: METs = -8.805 + (0.110 x steps/min) r2 = 0.830. Cross-validation was confirmed. CONCLUSIONS: Pedometer cut-points corresponding to minimal moderate intensity walking were 96 steps/min in men and 107 steps/min in women, or roughly 100 steps/min for both. This translates to approximately 3,000 steps in 30 min of moderate-intensity ambulatory activity for both genders.

• Effects of strength training and nutritional counseling on metabolic health indicators in aging women.

  Authors: Janne Sallinen, Mikael Fogelholm, Arto Pakarinen, Tuula Juvonen, Jeff S Volek, William J Kraemer, Markku Alen, Keijo Häkkinen

  Canadian journal of applied physiology = Revue canadienne de physiologie appliquée. 30(6):690-707.

  PURPOSE: Effects of strength training (ST) and nutritional counseling (NC) on metabolic health indicators were examined in 50 aging women. METHODS: Subjects performed ST for 21 weeks. NC was given toPURPOSE: Effects of strength training (ST) and nutritional counseling (NC) on metabolic health indicators were examined in 50 aging women. METHODS: Subjects performed ST for 21 weeks. NC was given to obtain sufficient energy and protein intake, and recommended intake of fat and fiber. RESULTS: NC increased intake of protein and polyunsaturated fat by 4.5% and 10.7% and decreased intake of saturated fat by 18.3%. Serum concentrations of total cholesterol (TC), LDL-cholesterol (LDL-C), total and HDL-cholesterol (HDL-C) ratio and triacylglycerols (TAG) decreased, and serum HDL-C increased in all subjects after ST. Respectively, systolic and diastolic blood pressure and serum insulin concentration decreased in all subjects. NC contributed to the decreases in levels of serum LDL-C after the first half of ST and serum TC and HDL-C ratio during both ST periods. Changes in serum TAG concentrations correlated positively with intake of carbohydrates, and negatively with monounsaturated fat in all subjects. Respectively, changes in serum TC levels were related to protein intake, and changes in serum HDL-C to intake of fat, and inversely to carbohydrate and protein in all subjects. Relationships between serum TC and HDL-C levels and protein intake were only observable in the ST+NC group. CONCLUSIONS: The long-term ST had favorable effects on serum lipids, lipoproteins, insulin concentration, and blood pressure. However, NC further contributed to positive changes in serum lipids and lipoproteins.

• Performing triple and quadruple figure skating jumps: implications for training.

  Authors: Deborah L King

  Canadian journal of applied physiology = Revue canadienne de physiologie appliquée. 30(6):743-53.

  The purpose of this paper is to review the biomechanics of triple and quadruple figure skating jumps, focusing on information that has implications for strength and conditioning programs. At aThe purpose of this paper is to review the biomechanics of triple and quadruple figure skating jumps, focusing on information that has implications for strength and conditioning programs. At a minimum, to complete the required revolutions in a jump, a skater must balance the average angular velocity with the time in the air. Vertical velocity at takeoff is similar in high revolution jumps to that in low revolution jumps; however, when comparing skaters of different abilities, those with higher abilities generate greater vertical velocities at takeoff for the same type of jump. Powerful extension of the legs is the primary factor in generating vertical velocity. Some jumps use asymmetrical extension of both legs, while other jumps involve extension of only one leg. Angular velocity is controlled primarily by the skater's moment of inertia, which means skaters must forcefully arrest the motion of the arms and legs after the propulsion phase and then quickly position the arms and legs close to the axis of rotation during flight. Training exercises that emphasize eccentric and concentric muscle actions and which are adaptable to asymmetrical or unilateral motions, such as box jumps and medicine ball throws, are a crucial component to off-ice training programs for figure skaters.

• Age and sex differences in blood lactate response to sprint running in elite master athletes.

  Authors: Marko T Korhonen, Harri Suominen, Antti Mero

  Canadian journal of applied physiology = Revue canadienne de physiologie appliquée. 30(6):647-65.

  The effect of age and sex on anaerobic glycolytic capacity in master athletes is currently unclear. To study this issue, we determined blood lactate concentrations after competitive sprint running inThe effect of age and sex on anaerobic glycolytic capacity in master athletes is currently unclear. To study this issue, we determined blood lactate concentrations after competitive sprint running in male and female master athletes of different age. Eighty-one men (40-88 yrs) and 75 women (35-87 yrs) participating in the sprint events (100-m, 200-m, 400-m) in the European Veterans Athletics Championships were studied. Blood samples were taken from the fingertip and analysed for peak lactate concentration ([La]bpeak). The [La]bpeak following 100-m to 400-m races showed a curvilinear decline (p < 0.001-0.05) with age in both men and women. However, the age related differences in the [La]b peak were not significant before 70 years of age. No significant sex related differences were found in [La]b peak for any sprint event. The [La]b peak correlated significantly (p < 0.001-0.05) with running times in all sprint distances except for the age-controlled correlation in men for the 100-m and 200-m. In conclusion, the present study showed age but not sex differences in blood lactate response to competitive sprint running in master athletes. Although the [La]b peak level of the athletes was considerably higher than that reported for untrained men and women, these cross-sectional findings suggest that anaerobic energy production from glycolysis declines in later years and may be a factor in the deterioration in sprint performance.

• Oxidative stress response in normal and antioxidant supplemented rats to a downhill run: changes in blood and skeletal muscles.

  Authors: Tongjian You, Allan H Goldfarb, Richard J Bloomer, Linh Nguyen, Xin Sha, Michael J McKenzie

  Canadian journal of applied physiology = Revue canadienne de physiologie appliquée. 30(6):677-89.

  The purpose of this study was to determine if changes in oxidative stress biomarkers in blood and skeletal muscles are similar in normal and antioxidant supplemented rats after a downhill run.The purpose of this study was to determine if changes in oxidative stress biomarkers in blood and skeletal muscles are similar in normal and antioxidant supplemented rats after a downhill run. Sixty-six male Sprague-Dawley rats were pretreated with a normal rat diet or diet + antioxidants (2,000 mg vitamin C + 1,000 IU vitamin E/kg diet) for 2 weeks. Exercised rats ran 90 min on a rodent treadmill at a speed of 16 m/min at -16 degrees grade. Rats were sacrificed either at rest, immediately, 2 hrs, or 48 hrs postexercise. Malondialdehyde (MDA) and protein carbonyl (PC) concentrations and glutathione status in blood, vastus lateralis (white fast-twitch), vastus intermedius (red fast-twitch), and soleus (slow-twitch) muscles were determined. A significant increase from rest in PC occurred in plasma, vastus intermedius and soleus muscle 2 hrs after the downhill run (p < 0.05), with no changes observed at any other times postexercise. Antioxidant supplementation significantly decreased PC concentrations in both vastus intermedius and soleus muscles at all times combined (p < 0.05). MDA and glutathione status in blood and muscles were unaffected by either the downhill run or antioxidant treatment. For PC and MDA, the concentrations were lower in blood as compared to skeletal muscle, with the opposite finding for oxidized glutathione; however, the pattern of response postexercise was similar. These data indicate that (a) PC, but not MDA or oxidized glutathione, is elevated transiently following downhill running in male rats; (b) the elevation in PC postexercise occurs in plasma, vastus intermedius, and soleus muscles; (c) antioxidant therapy can attenuate PC in vastus intermedius, and soleus muscles; and (d) while the concentrations of oxidative stress biomarkers differ between blood and the various skeletal muscles, the pattern of response postexercise is similar.

• Estimation of the parameters of the relationship between power and time to exhaustion from a single ramp test.

  Authors: Jean-Pierre Pouilly, Michel Chatagnon, Vincent Thomas, Thierry Busso

  Canadian journal of applied physiology = Revue canadienne de physiologie appliquée. 30(6):735-42.

  This study aimed to estimate the power/time relationship from a single ramp test (RT) assuming critical power (Pc) from ventilatory threshold (VT) and energy reserve (W') from total work during RTThis study aimed to estimate the power/time relationship from a single ramp test (RT) assuming critical power (Pc) from ventilatory threshold (VT) and energy reserve (W') from total work during RT These estimates from single RT were compared to those from a series of 4 constant power exercises (CPT) and from a series of 4 RT. Only W' from CPT was higher than from the series of RT and from single RT using VT (p < 0.05).

• Lifestyle modifications to prevent and manage hypertension for exercise physiologists and fitness professionals.

  Authors: Veronica K Jamnik, Norman Gledhill, Rhian M Touyz, Norman R C Campbell, Alexander G Logan, Raj Padwal, Rob Petrella

  Canadian journal of applied physiology = Revue canadienne de physiologie appliquée. 30(6):754-61.

  Information tailored to the interest of exercise physiologists and fitness professionals is provided regarding the Canadian Hypertension Society's 2005 evidence-based recommendations on lifestyleInformation tailored to the interest of exercise physiologists and fitness professionals is provided regarding the Canadian Hypertension Society's 2005 evidence-based recommendations on lifestyle modifications for the prevention and management of hypertension. The evidence from randomized controlled (RC) trials and systematic reviews of RC trials published in peer reviewed journals was reviewed by subject matter experts and then appraised independently by content and methodology experts. Blood pressure lowering was accepted as a primary outcome. All recommendations were debated and then voted on by the 43 members of the Canadian Hypertension Education Program's Evidence-Based Recommendations Task Force and achieved at least 95% consensus. Lifestyle modifications to prevent and/or manage hypertension include: (1) perform 30-60 minutes of aerobic exercise on 4- 7 days of the week; (2) maintain a healthy body weight (BMI 18.5-24.9 kg/m2) and waist circumference (<102 cm for men and <88 cm for women); (3) limit alcohol consumption to no more than 14 standard drinks per week in men or 9 standard drinks per week in women; (4) follow a diet that emphasizes fruits, vegetables, and low-fat dairy products and which is reduced in fat and cholesterol (DASH diet); (5) restrict salt intake; and (6) consider stress management in selected individuals.

• Oxidative stress after three different intensities of running.

  Authors: Cláudia Dornelles Schneider, Jaqueline Barp, Jerri Luiz Ribeiro, Adriane Belló-Klein, Alvaro Reischak Oliveira

  Canadian journal of applied physiology = Revue canadienne de physiologie appliquée. 30(6):723-34.

  In 8 trained subjects (T) and 9 untrained subjects (UT), lipid peroxidation (LPO), total antioxidant capacity (TRAP), superoxide dismutase, catalase, and glutathione peroxidase (GPx) activities wereIn 8 trained subjects (T) and 9 untrained subjects (UT), lipid peroxidation (LPO), total antioxidant capacity (TRAP), superoxide dismutase, catalase, and glutathione peroxidase (GPx) activities were measured in the blood before and after three different intensities of exercise on the treadmill, determined from ventilatory threshold and maximal oxygen uptake data, obtained from a maximal aerobic power test. In plasma, LPO decreased from 3589 +/- 193 to 3274 +/- 223 cps x mg Hb(-1) (p < 0.05), and TRAP increased from 304 +/- 45 to 384 +/- 57 micromol x L(-1) trolox (p < 0.05) after high intensity exercise in T. GPx activity increased in the T group as compared to the UT group, after exercise in moderate (25.90 +/- 3.79 to 15.05 +/- 3.23 nM x min(-1) x mg protein(-1)) and high (21.75 +/- 4.91 to 12.1 +/- 2.46 nM x min(-1) x mg protein(-1)) intensities (p < 0.05). Superoxide dismutase activity increased after exercise at low (8.35 +/- 0.85 to 9.23 +/- 1.03 U SOD x mg protein(-1)) and moderate (8.89 +/- 0.98 to 10.44 +/- 0.86 U SOD x mg protein(-1)) intensity in UT (p < 0.05). There were no changes in catalase activity. These findings indicate that exercise in this model did not increase lipid peroxidation, probably because of the alterations in TRAP and enzymatic antioxidants.

• The influence of the self-contained breathing apparatus (SCBA) on ventilatory function and maximal exercise.

  Authors: Neil D Eves, Richard L Jones, Stewart R Petersen

  Canadian journal of applied physiology = Revue canadienne de physiologie appliquée. 30(5):507-19.

  Our previous work showed that breathing low density gases during exercise with the self-contained breathing apparatus (SCBA) improves maximal ventilation (V(E)) and maximal oxygen consumptionOur previous work showed that breathing low density gases during exercise with the self-contained breathing apparatus (SCBA) improves maximal ventilation (V(E)) and maximal oxygen consumption (VO(2)max). This suggests that the SCBA limits exercise by adding a resistive load to breathing. In this study we compared VO(2)max with and without the various components comprising the SCBA to determine their impact on VO(2)max. Twelve males performed 4 randomly ordered incremental exercise tests to exhaustion on a treadmill: (1) low-resistance breathing valve only (CON); (2) full SCBA (SCBA); (3) SCBA regulator only (REG); and (4) carrying the cylinder and harness assembly but breathing through a low-resistance breathing valve (PACK). Compared to CON, VO(2)max was reduced to a similar extent in the SCBA and REG trials (14.9% and 13.1%, respectively). The PACK condition also reduced VO(2)max, but to a lesser extent (4.8 +/- 5.3%). At VO(2)max, VE was decreased and expiratory mouth pressure and external breathing resistance (BR) were increased in both the SCBA and REG trials. There was a significant correlation between the change in maximal V(E)and VO(2)max with the SCBA. The results show that the SCBA reduces VO(2)max by limiting V(E) secondary to the increased BR of the SCBA regulator.

• Blood flow to exercising limbs varies with age, gender, and training status.

  Authors: Dennis W Koch, Sean C Newcomer, David N Proctor

  Canadian journal of applied physiology = Revue canadienne de physiologie appliquée. 30(5):554-75.

  Understanding the effects of physiological aging on blood flow to active skeletal muscle and its regulation during exercise has important functional, hemodynamic, and metabolic implications for ourUnderstanding the effects of physiological aging on blood flow to active skeletal muscle and its regulation during exercise has important functional, hemodynamic, and metabolic implications for our rapidly expanding elderly population. During peak exercise involving a large muscle mass, blood flow to the legs is lower in healthy older compared to younger persons; this results from central (reduced cardiac output) and peripheral (reduced leg vascular conductance) limitations. There is considerable variability in the literature concerning age-related changes in leg blood flow during submaximal exercise, with reports of similar or reduced leg blood flow and vascular conductance in older vs. younger subjects depending on the exercise intensity and the gender and training status of the subjects. However, all the studies involving non-endurance-trained subjects are consistent in that older subjects achieve the requisite leg blood flow at higher arterial perfusion pressures than young subjects, suggesting altered local vasoregulatory mechanisms with aging. Although the nature of these age-related alterations is poorly understood, we have preliminary evidence for augmented sympathetic vasoconstrictor responsiveness in the legs of older men during exercise, and blunted leg vasodilator responsiveness in older women. Systematic research will be needed in order to define the central and local mechanisms underlying these age- and gender-specific differences in muscle vascular responsiveness. Such information will be important for designing future interventions aimed at improving muscle blood supply and functional capacity in older persons.

• Muscle hypertrophy models: applications for research on aging.

  Authors: Stephen E Alway, Parco M Siu, Zsolt Murlasits, David C Butler

  Canadian journal of applied physiology = Revue canadienne de physiologie appliquée. 30(5):591-624.

  Muscle hypertrophy is an adaptive response to overload that requires increasing gene transcription and synthesis of muscle-specific proteins resulting in increased protein accumulation. ProgressiveMuscle hypertrophy is an adaptive response to overload that requires increasing gene transcription and synthesis of muscle-specific proteins resulting in increased protein accumulation. Progressive resistance training (P(RT)) is thought to be among the best means for achieving hypertrophy in humans. However, hypertrophy and functional adaptations to P(RT) in the muscles of humans are often difficult to evaluate because adaptations can take weeks, months, or even years before they become evident, and there is a large variability in response to P(RT) among humans. In contrast, various animal models have been developed which quickly result in extensive muscle hypertrophy. Several such models allow precise control of the loading parameters and records of muscle activation and performance throughout overload. Scientists using animal models of muscle hypertrophy should be familiar with the advantages and disadvantages of each and thereby choose the model that best addresses their research question. The purposes of this paper are to review animal models currently being used in basic research laboratories, discuss the hypertrophic and functional outcomes as well as applications of these models to aging, and highlight a few mechanisms involved in regulating hypertrophy as a result of applying these animal models to questions in research on aging.

• VO2 responses to intermittent swimming sets at velocity associated with VO2max.

  Authors: Sebastien Libicz, Belle Roels, Gregoire P Millet

  Canadian journal of applied physiology = Revue canadienne de physiologie appliquée. 30(5):543-53.

  While the physiological adaptations following endurance training are relatively well understood, in swimming there is a dearth of knowledge regarding the metabolic responses to interval trainingWhile the physiological adaptations following endurance training are relatively well understood, in swimming there is a dearth of knowledge regarding the metabolic responses to interval training (IT). The hypothesis tested predicted that two different endurance swimming IT sets would induce differences in the total time the subjects swam at a high percentage of maximal oxygen consumption (VO(2)max). Ten trained triathletes underwent an incremental test to exhaustion in swimming so that the swimming velocity associated with VO(2)max (vVO(2)max) could be determined. This was followed by a maximal 400-m test and two intermittent sets at vVO(2)max: (a) 16 x 50 m with 15-s rest (IT(50)); (b) 8 x 100 m with 30-s rest (IT(100)). The times sustained above 95% VO(2)max (68.50 +/- 62.69 vs. 145.01 +/- 165.91 sec) and 95% HRmax (146.67 +/- 131.99 vs. 169.78 +/- 203.45 sec, p = 0.54) did not differ between IT(50) and IT(100)(values are mean +/- SD). In conclusion, swimming IT sets of equal time duration at vVO(2)max but of differing work-interval durations led to slightly different VO(2)and HR responses. The time spent above 95% of VO(2)max was twice as long in IT(100) as in IT (50), and a large variability between mean VO(2)and HR values was also observed.

• The versatility of the pump-perfused rat hindlimb preparation: examples relating to skeletal muscle function and energy metabolism.

  Authors: David J Baker, Russell T Hepple

  Canadian journal of applied physiology = Revue canadienne de physiologie appliquée. 30(5):576-90.

  The pump-perfused rat hindlimb model, in various forms, has been in use for several decades. There are many applications for this model, owing to the ability to control the content and rate ofThe pump-perfused rat hindlimb model, in various forms, has been in use for several decades. There are many applications for this model, owing to the ability to control the content and rate of perfusion. In the context of exercise physiology this model has been put to particularly good use. In this report we summarize some of the central surgical differences between different versions of the pump-perfused rat hindlimb model, including the double hindlimb + trunk, double hindlimb alone, single hindlimb, and distal hindlimb-alone models. We also summarize specific elements of the perfusion medium and measurement of force used in our lab during assessment of muscle metabolic and contractile responses, and illustrate some of the differences from the in vivo condition that merit consideration. We then provide specific examples of how the single pump-perfused hindlimb and distal hindlimb-alone versions of this model have been used to study muscle function and energy metabolism. In this context we show how this model can be used to permit the experimenter to manipulate and control the rate of O(2)delivery and to add specific compounds that inhibit a particular aspect of muscle metabolism, such that in combination with measurements of the flux of specific substances across the muscle and/or fast-freezing of muscle after contractions, more can be understood about the metabolic state of the contracting muscles.

• Application of animal models: chronic electrical stimulation-induced contractile activity.

  Authors: Vladimir Ljubicic, Peter J Adhihetty, David A Hood

  Canadian journal of applied physiology = Revue canadienne de physiologie appliquée. 30(5):625-43.

  Unilateral, chronic low-frequency electrical stimulation (CLFS) is an experimental model that evokes numerous biochemical and physiological adaptations in skeletal muscle. These occur within a shortUnilateral, chronic low-frequency electrical stimulation (CLFS) is an experimental model that evokes numerous biochemical and physiological adaptations in skeletal muscle. These occur within a short time frame and are restricted to the stimulated muscle. The humoral effects of whole body exercise are eliminated and the nonstimulated contralateral limb can often be used as a control muscle, if possible effects on the contralateral side are considered. CLFS induces a fast-to-slow transformation of muscle because of alterations in calcium dynamics and myofibrillar proteins, and a white-to-red transformation because of changes in mitochondrial enzymes, myoglobin, and the induction of angiogenesis. These adaptations occur in a coordinated time-dependent manner and result from altered gene expression, including transcriptional and posttranscriptional processes. CLFS techniques have also been applied to myocytes in cell culture, which provide a greater opportunity for the delivery of pharmacological agents or for the application of gene transfer methodologies. Clinical applications of the CLFS technique have been limited, but they have shown potential therapeutic value in patients in whom voluntary muscle contraction is not possible due to debilitating disease and/or injury. Thus the CLFS technique has great value for studying various aspects of muscle adaptation, and its wider scientific application to a variety of neuromuscular-based disorders in humans appears to be warranted.

• Attenuation of protective effect against eccentric exercise-induced muscle damage.

  Authors: Kazunori Nosaka, Michael J Newton, Paul Sacco

  Canadian journal of applied physiology = Revue canadienne de physiologie appliquée. 30(5):529-42.

  A single bout of eccentric exercise confers a long-lasting protective effect against subsequent bouts of the same exercise. This study investigated how the protective effect was lessened when theA single bout of eccentric exercise confers a long-lasting protective effect against subsequent bouts of the same exercise. This study investigated how the protective effect was lessened when the interval between the initial and secondary exercise bouts was increased from 4 to 12 weeks. Thirty young men performed two bouts of 12 maximal eccentric actions of the elbow flexors of the nondominant arm separated by either 4 (n = 9), 8 (n = 10), or 12 (n = 11) weeks. Maximal isometric strength, flexed and relaxed elbow joint angles, range of motion, upper arm circumference, muscle soreness, plasma creatine kinase (CK), and myoglobin (Mb) were measured before, immediately after, and for 4 days after exercise. Changes in criterion measures were compared between bouts for each group and among groups by two-way repeated-measures ANOVA. There were no significant differences among groups in the changes in all measures following the first bout. Significantly (p < 0.05) smaller responses in all measures were observed after the second bout as compared with first bout for the 4 and 8 weeks, but only in strength, muscle soreness, CK, and Mb for the 12 weeks. It was concluded that some aspects of the protective effect were attenuated after 8 weeks, and the factors responsible for the effect vary among the measures.

• Effect of endurance training on different mechanical efficiency indices during submaximal cycling in subjects unaccustomed to cycling.

  Authors: Frédérique Hintzy, Laurent Mourot, Stéphane Perrey, Nicolas Tordi

  Canadian journal of applied physiology = Revue canadienne de physiologie appliquée. 30(5):520-8.

  The purpose of this study was to evaluate different efficiency indices, i.e., gross (GE: no baseline correction), net (NE: resting metabolism as baseline correction), and work (WE: unloaded exerciseThe purpose of this study was to evaluate different efficiency indices, i.e., gross (GE: no baseline correction), net (NE: resting metabolism as baseline correction), and work (WE: unloaded exercise as baseline correction), to reveal the effect of endurance training on mechanical efficiency. Nine healthy sedentary women undertook an incremental test and submaximal cycling exercise, at an intensity corresponding to 50% of the pretraining peak oxygen uptake, before and after 6 weeks of endurance training (18 sessions of 45 min). The training effects on efficiency indices were tested by comparisons based on GE, NE, and WE as well as by the differences between the percentage changes of all indices (%GE, %NE, %WE). Endurance training resulted in significantly higher GE (+11.1%; p < 0.001) and NE (+9.1%; p < 0.01). Only minor significant improvement (+2.4%; p < 0.05) was observed with the WE index because the value used for baseline subtraction was significantly reduced by the training sessions, due perhaps to improvement in pedaling skill. As a consequence, %WE was significantly lower than %GE (p < 0.01) and %NE (p < 0.05), while %GE and %NE were not significantly different. We conclude that mechanical efficiency of cycling increases with training in women previously unfamiliar with cycling, and that the WE index is less sensitive to this training effect than GE and NE indices.

• Does prior 1500-m swimming affect cycling energy expenditure in well-trained triathletes?

  Authors: Anne Delextrat, Jeanick Brisswalter, Christophe Hausswirth, Thierry Bernard, Jean-Marc Vallier

  Canadian journal of applied physiology = Revue canadienne de physiologie appliquée. 30(4):392-403.

  The purpose of this study was to determine the effects of a 1,500-m swim on energy expenditure during a subsequent cycle task. Eight well-trained male triathletes (age 26.0 +/- 5.0 yrs; height 179.6The purpose of this study was to determine the effects of a 1,500-m swim on energy expenditure during a subsequent cycle task. Eight well-trained male triathletes (age 26.0 +/- 5.0 yrs; height 179.6 +/- 4.5 cm; mass 71.3 +/- 5.8 kg; VO(2)max 71.9 +/- 7.8 ml.kg(-1).min(-1)) underwent two testing sessions in counterbalanced order. The sessions consisted of a 30-min ride on the cycle ergometer at 75% of maximal aerobic power (MAP), and at a pedaling frequency of 95 rev.min(-1), preceded either by a 1,500-m swim at 1.20 m.s(-1) (SC trial) or by a cycling warm-up at 30% of MAP (C trial). Respiratory and metabolic data were collected between the 3rd and the 5th min, and between the 28th and 30th min of cycling. The main results indicated a significantly lower gross efficiency (13.0%) and significantly higher blood lactate concentration (56.4%), VO(2) (5.0%), HR (9.3%), VE (15.7%), and RF (19.9%) in the SC compared to the C trial after 5 min, p < 0.05. After 30 min, only VE (7.9%) and blood lactate concentration (43.9%) were significantly higher in the SC compared to the C trial, p < 0.05. These results confirm the increase in energy cost previously observed during sprint-distance triathlons and point to the importance of the relative intensity of swimming on energy demand during subsequent cycling.

• Chronic but not acute oral L-arginine supplementation delays the ventilatory threshold during exercise in heart failure patients.

  Authors: Stéphane Doutreleau, Bertrand Mettauer, François Piquard, Adrien Schaefer, Evelyne Lonsdorfer, Ruddy Richard, Bernard Geny

  Canadian journal of applied physiology = Revue canadienne de physiologie appliquée. 30(4):419-32.

  The purpose of this study was to determine, in heart failure patients (HF), whether acute or chronic L-arginine supplementation (LAS) might delay the ventilatory threshold (VT) and whether chronicThe purpose of this study was to determine, in heart failure patients (HF), whether acute or chronic L-arginine supplementation (LAS) might delay the ventilatory threshold (VT) and whether chronic LAS might reduce exercise-induced plasma lactate increase. HF patients undertook 4 cardiopulmonary bicycle exercises tests. The first 3 were maximal without (EX(1)), after acute (EX(2)), or chronic (EX(3)) oral LAS (6 gm twice a day for 6 weeks). The 4th test (EX(4)) performed after chronic LAS, was similar to the first in order to investigate the effect of chronic LAS on circulating lactate levels. Results showed that acute LAS failed to improve both submaximal and maximal exercise capacities. Similarly, maximal exercise capacity remained unmodified after chronic LAS. Nevertheless, chronic LAS delayed significantly the patients' ventilatory threshold. Thus exercise duration prior to VT increased (mean +/- SEM) from 6.04 +/- 0.9 to 7.7 +/- 1.03 min (p = 0.04), resulting in a significant increase in oxygen uptake (1.05 +/- 0.08 to 1.24 +/- 0.12 L.min(-1); p = 0.03), CO(2) release (0.94 +/- 0.10 to 1.2 +/- 0.12 L.min(-1); p = 0.018), minute ventilation (29.31 +/- 2.8 to 34.5 +/- 2.7 L; p = 0.009), and workload (60.7 +/- 9.8 to 78.5 +/- 10.2 watts; p = 0.034). Furthermore, chronic LAS significantly reduced the exercise-induced increase in postexercise plasma lactate concentration (-21 +/- 7%). In conclusion, unlike acute supplementation, chronic LAS significantly delays the ventilatory threshold, and chronic LAS reduces circulating plasma lactate in HF patients. These data suggest that chronic LAS might improve the ability of HF patients to perform their daily-life activities.

• Vascular nitric oxide and oxidative stress: determinants of endothelial adaptations to cardiovascular disease and to physical activity.

  Authors: James W E Rush, Steven G Denniss, Drew A Graham

  Canadian journal of applied physiology = Revue canadienne de physiologie appliquée. 30(4):442-74.

  Cardiovascular disease is the single leading cause of death and morbidity for Canadians. A universal feature of cardiovascular disease is dysfunction of the vascular endothelium, thus disruptingCardiovascular disease is the single leading cause of death and morbidity for Canadians. A universal feature of cardiovascular disease is dysfunction of the vascular endothelium, thus disrupting control of vasodilation, tissue perfusion, hemostasis, and thrombosis. Nitric oxide bioavailability, crucial for maintaining vascular endothelial health and function, depends on the processes controlling synthesis and destruction of nitric oxide as well as on the sensitivity of target tissue to nitric oxide. Evidence supports a major contribution by oxidative stress-induced destruction of nitric oxide to the endothelial dysfunction that accompanies a number of cardiovascular disease states including hypertension, diabetes, chronic heart failure, and atherosclerosis. Regular physical activity (exercise training) reduces cardiovascular disease risk. Numerous studies support the hypothesis that exercise training improves vascular endothelial function, especially when it has been impaired by preexisting risk factors. Evidence is emerging to support a role for improved nitric oxide bioavailability with training as a result of enhanced synthesis and reduced oxidative stress-mediated destruction. Molecular targets sensitive to the exercise training effect include the endothelial nitric oxide synthase and the antioxidant enzyme superoxide dismutase. However, many fundamental details of the cellular and molecular mechanisms linking exercise to altered molecular and functional endothelial phenotypes have yet to be discovered. The working hypothesis is that some of the cellular mechanisms contributing to endothelial dysfunction in cardiovascular disease can be targeted and reversed by signals associated with regular increases in physical activity. The capacity for exercise training to regulate vascular endothelial function, nitric oxide bioavailability, and oxidative stress is an example of how lifestyle can complement medicine and pharmacology in the prevention and management of cardiovascular disease.

• The effect of sweetness on the efficacy of carbohydrate supplementation during exercise in the heat.

  Authors: James Carter, Asker E Jeukendrup, David A Jones

  Canadian journal of applied physiology = Revue canadienne de physiologie appliquée. 30(4):379-91.

  The aim of the present study was to investigate potential mechanisms responsible for the improvement in prolonged exercise capacity in hot environments with exogenous carbohydrate. EightThe aim of the present study was to investigate potential mechanisms responsible for the improvement in prolonged exercise capacity in hot environments with exogenous carbohydrate. Eight endurance-trained men (VO(2)max 60.5 +/- 2.4 ml.kg(-1).min(-1), mean +/- SE) cycled to exhaustion on three occasions at 60% VO(2)max at an ambient temperature of 35 degrees C. They ingested either a sweet 6.4% carbohydrate solution (SC), a nonsweet 6.4% carbohydrate solution (NSC), or water (W). Exercise capacity was significantly increased with SC and NSC compared to W, the improvements corresponding to 15.8% and 11.8%, respectively. No difference in exercise capacity was seen between SC and NSC solutions. Plasma glucose concentrations were higher during the SC and NSC trials compared to W, significantly so at 10 min and at fatigue. Rates of carbohydrate oxidation were higher in the SC and NSC trials, although the rates never declined below 2.1 +/- 0.2 g.min(-1) in the W trial. There was no difference in the rate of rise of rectal temperature between trials, but there was a trend for subjects to fatigue at higher temperatures during the two carbohydrate trials. In conclusion, exogenous carbohydrate, independent of sweetness, improves exercise capacity in the heat compared to water alone.

• [Comparison of male and female thermal, cardiac, and muscular responses induced by a prolonged run undertaken in a hot environment.]

  Authors: Foued Ftaiti, Asma Kacem, Imed Latiri, Samia Ben Mdalla, Zouhair Tabka, Nouri Zouari, Feriel Ellouze, Laurent Grélot

  Canadian journal of applied physiology = Revue canadienne de physiologie appliquée. 30(4):404-18.

  The aim of this study was to compare male and female thermal, cardiac, and muscular responses induced by a prolonged run undertaken in a hot environment. Twelve volunteers participated in this study.The aim of this study was to compare male and female thermal, cardiac, and muscular responses induced by a prolonged run undertaken in a hot environment. Twelve volunteers participated in this study. The first group consisted of 6 men and the second one consisted of 6 women. After determination of their VO(2)max and maximal aerobic velocity (MAV), each athlete completed a 40-min run at 65% MAV in a hot and dry environment (temperature 31-33 degrees C, relative humidity 30%). Immediately before and after the run, each subject performed two different vertical jumps, i.e., a squat jump (SJ) and a counter-movement jump (CMJ) on a force platform. Force, velocity, power, and jump height were measured during each jump. The completion of the run was associated with a significant loss (p < 0.001) of body mass (BM) and significant increases (p < 0.001) in heart rate, tympanic temperature, and lactate concentration ([La]). Muscle power was significantly improved (+9%, p < 0.05) during the SJ only in the women. A significant enhancement of this parameter was also demonstrated during the CMJ in both groups (men: +10%, p < 0.05; women: +8%, p < 0.01). Surprisingly, a comparison of thermal, cardiac, and muscular responses did not reveal any significant differences between the sexes. Moderate dehydration (-2.0 to -2.3% of BM) and a rise in core temperature (above 39.2 degrees C) induced by the 40-min run led to an improvement of muscular strength in both men and women. However, the results of this study did not reveal any significant between-sex differences in thermal, cardiac, and muscular responses after exercising in the heat.

• Torso stabilization reduces the metabolic cost of producing cycling power.

  Authors: John McDaniel, Andrew Subudhi, James C Martin

  Canadian journal of applied physiology = Revue canadienne de physiologie appliquée. 30(4):433-41.

  Many researchers have used cycling exercise to evaluate muscle metabolism. Inherent in such studies is an assumption that changes in whole-body respiration are due solely to respiration at theMany researchers have used cycling exercise to evaluate muscle metabolism. Inherent in such studies is an assumption that changes in whole-body respiration are due solely to respiration at the working muscle. Some researchers, however, have speculated that the metabolic cost of torso stabilization may contribute to the metabolic cost of cycling. Therefore, our primary purpose was to determine whether a torso stabilization device would reduce the metabolic cost of producing cycling power. Our secondary purpose was to determine the validity of the ergometer used in this study. Nine male cyclists cycled on a Velotron cycle ergometer at mechanical power outputs intended to elicit 50, 75, and 100% of their ventilatory threshold at 40, 60, and 80 rpm, with and without torso stabilization. Power was controlled by the Velotron in iso-power mode and measured with an SRM powermeter. We determined metabolic cost by indirect calorimetery and recorded power output. Torso stabilization significantly reduced metabolic cost of producing submaximal power (1%), and reduction tended to be greatest at the lower pedaling rates where pedaling force was greatest (1.6% at 40 rpm, 1.2% at 60 rpm, 0.2% at 80 rpm). Power, measured with the SRM powermeter, was strongly correlated with that specified to the Velotron ergometer control unit (R(2) > 0.99). We conclude that muscular contractions associated with torso stabilization elicit significant metabolic costs, which tend to be greatest at low pedaling rates. Researchers who intend to make precise inferences regarding metabolism in the working muscles of the legs may wish to provide torso stabilization as a means of reducing variability, particularly when comparing metabolic data across a wide range of pedaling rates.

• Maximizing acute fat utilization: effects of exercise, food, and individual characteristics.

  Authors: Patrick Bennard, Pascal Imbeault, Eric Doucet

  Canadian journal of applied physiology = Revue canadienne de physiologie appliquée. 30(4):475-99.

  In discussion of the physiological mechanisms that regulate fat metabolism, and with consideration of the metabolic stimuli that modulate substrate metabolism, the issue of how an acute state ofIn discussion of the physiological mechanisms that regulate fat metabolism, and with consideration of the metabolic stimuli that modulate substrate metabolism, the issue of how an acute state of negative lipid balance can be maximized is addressed. The regulation of lipolysis by catecholamines and insulin is reviewed, and the mechanisms of fatty acid mobilization and uptake by muscle are also briefly discussed. The implications of substrate availability and the hormonal response during physiological states such as fasting, exercise, and after food intake are also addressed, with particular regard to the influences on fatty acid mobilization and/or oxidation from eliciting these stimuli conjointly. Finally, a brief discussion is given of both the nature of exercise and the exercising individual, and how these factors influence fat metabolism during exercise. It is also a primary thrust of this paper to underline gaps in the existing literature with regard to exercise timing concerning food ingestion for maximizing acute lipid utilization.

• Motoneurones "learn" and "forget" physical activity.

  Authors: Phillip Gardiner, Eric Beaumont, Bruno Cormery

  Canadian journal of applied physiology = Revue canadienne de physiologie appliquée. 30(3):352-70.

  In spite of our knowledge of activity related adaptations in supraspinal neurones and skeletal muscles, very little is known concerning adaptations in alpha-motoneurones to alterations in chronicIn spite of our knowledge of activity related adaptations in supraspinal neurones and skeletal muscles, very little is known concerning adaptations in alpha-motoneurones to alterations in chronic activity levels. Recent evidence shows that the biophysical properties of alpha-motoneurones are plastic and adapt to both increases and decreases in chronic activation. The nature of the adaptations--in resting membrane potential, spike threshold, afterhyper-polarization amplitude,and rate of depolarization during spike generation--point to involvement of density, type, location, and/or metabolic modulation of ion conductance channels in the motoneuronal membrane. These changes will have significant effects on how motoneurones respond when activated during the generation of movements, and on the effort required to sustain activation during prolonged exercise. Since the adaptations most likely involve structural changes in the motoneurones and changes in protein synthesis, and change the output response of the cells to input, they are considered to be learning responses. Future research directions for examining this issue are outlined.

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